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Photo Glossary - A

Abbe number - denotes the degree of refraction of light of different wavelengths to different extents, given by a transparent material, such as glass. The lower the Abbe number, the greater the dispersion of colors.

Aberration - the inability of a lens to produce a perfect, sharp image, especially towards the edge of the lens field. These faults can be reduced by compound lens constructions, and the use of small apertures.

Abrasion marks - marks on the emulsion surface of a film, caused by scratching. It can be due to traces of dirt trapped between layers of film as it is wound on the spool, or to grit on the pressure plate.

Absolute released images - any images for which signed model or property releases are on file and immediately available.

Absolute temperature - the temperature at which most molecular movement ceases. It is often referred to as absolute zero (-273° C).

Absorption - the process by which light falling on a surface is partially absorbed by the surface.

Abstract - subjective, non-realistic image. An abstraction photograph generally contains a design of patterns or shapes where the identity of a subject is not evident.

Accelerator - chemical added to a developing solution to speed up the slow working action of the reducing agents in the solution.

Acceptable Circle of Confusion - the size of the largest circle which the eye cannot distinguish from a dot. In 35mm format cameras, a 0.03mm diameter circle of confusion is considered acceptable. It is used to calculate depth-of-field or depth of focus.

Acceptance angle - see Angle of View.

Accessory shoe - metal or plastic fitting on the top of the camera which supports accessories such as viewfinder, rangefinder, or flash gun.

Acetate base - non-inflammable base support for film emulsions which replaced the highly inflammable cellulose nitrate base.

Acetic acid - chemical used for stop baths and to acidify acid fixing solution.

Acetone - solvent chemical used in certain processing solutions that contain materials not normally soluble in water.

Achromatic - lens system that has been corrected for chromatic aberration.

Acid - chemical substance with a pH value below 7.

Acid fixing solutions - solutions which contain an acid to neutralize any carry-over of alkaline developer on the negative or print.

Acid hardener - substance used in acid fixer to help harden the gelatin of the emulsion.

Acid rinse - weak acid solution used after development and before fixation. By neutralizing alkaline developer left on the photographic material it arrests development.

Actinic - the ability of light to cause a chemical or physical change in a substance.

Actinometer - early type of exposure calculator.

Acuity - subjective term for the visual sharpness of an image.

Acutance - objective measurement of image sharpness.

Adapter ring - circular mount, available in several sizes, enabling accessories such as filters to be used with lenses of different diameters.

Additive color - see Additive Printing.

Additive printing - color printing method which produces an image by giving three separate exposures, each filtered to one of the three primary color wavelengths, blue, green and red.

Additive synthesis - method of producing full-color images by mixing light of the three primary color wavelengths, blue, green and red.

Aerial perspective - the distance or depth effect caused by atmospheric haze. Haze creates a large amount of extraneous ultra-violet light to which all photographic emulsions are sensitive.

AF lock - stops autofocus operation once the subject is in focus. Useful when shooting a subject outside the focus area in the viewfinder. The photographer should first lock the focus with the subject inside the focus area, then recompose the shot as neccesary.

Afocal lens - lens attachment that alters the focal length of the camera lens without disturbing the distance between the lens and the film plane.

AF Sensor - the sensor used to detect focus.

Aftertreatment - the treatment of negatives and prints to correct certain faults in exposure and development, or to create special effects.

Agitation - method by which fresh solution is brought into contact with the surface of sensitive materials during photographic processing.

Air bells - bubbles of air clinging to the emulsion surface during processing.

Air brushing - method of retouching b&w or color photographs where dye is sprayed, under pressure, on to selected areas of the negative or print.

Air-to-air photography - photography of aircraft in flight from another aircraft.

Albert effect - effect that creates a reversed image. An exposed frame of film, treated with dilute chromic acid is exposed to light. Development then gives a positive image by darkening the film grains that were not initially affected by exposure.

Albumen paper - printing paper invented by Blanquart-Evrard in the mid-19th century where egg whites were used to coat the paper base prior to sensitization. The albumen added to the brightness of the white base and substantially improved printed highlights.

Alcohol thermometer - instrument used for measuring temperature. It is an inexpensive and less accurate version of the mercury thermometer.

Alkalinity - denotes the degree of alkali in a solution, measured in pH values. All values above pH 7 are alkaline.

Allegory - work of art that treats one subject in the guise of another. An allegoric photograph usually illustrates a subject that embodies a moral "inner meaning".

Alum - chemical used in acid hardening fixing baths.

Aluminum compounds - groups of chemicals often used as hardeners in fixing baths.

Ambient light - the available light surrounding a subject. Light already existing in an indoor or outdoor setting that is not caused by any illumination supplied by the photographer.

Ambrotype - Mid-19th century photographic process introduced in 1851-52 by Frederick Scott Archer and Peter Fry. It used weak collodion negatives which were bleached and backed by a black background which produced the effect of a positive image.

Amidol - soluble reducing agent which works at low pH values.

Ammonium chloride - chemical used in toners and bleachers.

Ammonium persulfate - chemical used in super-proportional reducers.

Ammonium sulfide - pungent but essential chemical in sulfide or sepia toning.

Ammonium thiosulfate - highly active fixing agent used in rapid fixing solutions which works by converting unused silver halides to soluble complexes.

Amphitype - Mid-19th Century process based on an underexposed albumen-on-glass negative. This was viewed by reflected light against a black background to give a positive image similar to a ambrotype.

Anaglyph - result of forming stereoscopic pairs from two positives each dyed a different color, usually green or red.

Analyzer - chart, grid or electronic instrument used to determine correct color filtration when making color prints.

Anamorphic lens - lens capable of compressing a wide angle of view into a standard frame.

Anastigmat - compound lens which has been corrected for the lens aberration "astigmatism".

Angle of incidence - when light strikes a surface it forms an angle with an imaginary line known as the :normal," which is perpendicular to the surface. The angle created between the incident ray and the normal is referred to as the angle of incidence.

Angle of view - is the maximum angle of acceptance of a lens which is capable of producing an image of usable quality on the film.

Angstrom - unit of measurement used to indicate specific points of wavelengths within the electromagnetic spectrum. Visible light rays occur between 4000 - 7000 Å.

Angular field - the angle subtended at the lens by the diameter of the largest circle within which the lens gives an image of acceptable sharpness and even illumination.

Anhydrous - dehydrated form of chemical. More concentrated, so that less weight is needed in a formula than the crystalline kind.

ANSI - speed rating system for photographic materials devised by the American National Standards Institute.

Anti-fogging agent - constituent of a developer that inhibits or reduces fogging during development.

Antihalation backing - dye used on the back of most films capable of absorbing light which passes straight through the emulsion. In this way it reduces the amount of extraneous light that can be reflected from the camera back through the emulsion.

Antinous release - alternate term for a camera cable release.

Antiscreen plates - photographic plates containing dyes that reduce the blue sensitivity. Used unfiltered, they can give results similar to those obtained with yellow filtered orthochromatic plates.

A-PEN - annealed polyethylene naphthalate. A polyester material used as the base on Advanced Photo System film.

Aperture - circular hole in the front of the camera lens which controls the amount of light allowed to pass on to the film.

Aperture priority camera - semi-automatic camera on which the photographer sets the aperture and the camera automatically sets the shutter speed.

Aperture ring - ring located on the outside of the lens usually behind the focusing ring, which is linked mechanically to the diaphragm to control the size of the aperture.

Aplanat - lens which has been corrected for spherical aberration.

Apochromat - lens corrected for chromatic aberration in all three primary colors.

APO (Apochromatic) - the ability to bring all colors of the visible spectrum to a common plane of focus, within close tolerances. It usually refers to a lens with such superior color correction.

Apodization - lens treatment designed to cut down diffraction fringes that appear around the images bright points of light.

APS (Advanced Photo System) - consumer photography developed by Kodak and four other companies - Canon, Fuji, Minolta and Nikon . It is based on a new film format and photofinishing technologies.

Aquatint - etching technique allowing control of tonal areas to produce almost unlimited gradations from pale gray to black. Because of this it has also been used in photography as an alternative term for gum bichromate process.

Archival permanence treatments - various treatments given to prints to make them fade-resistant.

Arc lamp - photographic lamp in which light is produced by passing an electric current through two carbon rods.

Argentotype - Mid-19th century silver print process, on which the kallitype and sepia paper processes are based.

Aristotype - early commercial print type made on collodion-chloride or gelatin-chloride paper.

Artificial daylight - artificial light having a similar color temperature to daylight.

Artificial light - all light not originating from a natural source - normally the sun.

Artificial light film - color film balanced for use ion tungsten Artificial light, usually 3200 K.

ASA - original system of rating photographic materials, which was devised by the American standards Association. The ISO rating system is now used in place of the ASA.

Aspect ratio - ratio of width to height in photographic prints. The ratio is 2:3 in 35 mm pictures which produces photographs most commonly measuring 3.5 x 5 inches or 4 x 6 inches.

Aspherical lens - lens with a curved, non-spherical surface. Used to reduce aberrations and enable a more compact lens size.

Aspherical surface - lens surface with more than one radius of curvature, i.e. the surface does not form part of a sphere.

Assembly printing - method of printing using image separations. Yellow, magenta, and cyan films are stacked to make a final, full color print.

Assignment - definite OK to take photos for a specific client with mutual understanding as to the provisions and terms involved.

Astigmatism - lens aberration making a single point light source impossible to focus as a true point.

ATA - term used to describe a camera, which supports the electrical interface standard, defined by the PC Card Association (formerly PCMCIA), known as ATA (AT Attachment). This is the mobile computing equivalent of the IDE standard for desktop computers.

Atmospheric perspective - alternative term for aerial perspective.

Audiovisual - materials such as filmstrips, motion pictures and overhead transparencies which use audio backup for visual material.

Autochrome - early commercial color photography process in which the principles of additive color synthesis were applied.

Autofocus - device used in certain cameras, projectors and enlargers that focuses the image automatically.

Automatic aperture - lens aperture mechanism that stops down to s preset size just as the shutter is fired, afterwards returning to the maximum aperture again for focusing and composing the next image.

Automatic exposure control - system of exposure setting in a camera, in which the electric current produced or inhibited by the action of light on a photoelectric cell operates a mechanism that adjusts the aperture and/or the shutter speed automatically.

Automatic iris - lens diaphragm which is controlled by a mechanism in the camera body coupled to the shutter release.

Automatic lens - lens which remains at full aperture whatever working aperture is set, until the shutter is released. This allows optimum focusing, without affecting metering. Also referred to as Automatic aperture.

Autowinder - film wind-on mechanism which moves the film on one frame each time the shutter is released.

AV - see Audiovisual.

Available light - term applying to light normally occurring in a scene, not supplemented by illumination intended specifically for photography.

Axis lighting - light pointed at the subject from a position close to the lens.

Azo dyes - compounds forming colors of great strength and purity. Used in camera filters and integral tripack dye-bleach materials.

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Photo Glossary - B

B (Bulb) - letter on the shutter dial indicating that the shutter will stay open while the release is depressed.

Back focus - distance between the back surface of the lens and the image plane, when the lens is focused at infinity.

Background - area shown behind the main subject in a picture.

Background density - density of any selection of a negative or print on which there is no image. Also referred to as Fog level.

Backing - dark coating, normally on the back of a film, but sometimes between emulsion and base, to reduce halation. The backing dye disappears during processing.

Back-lighting - light coming from behind the subject.

Back printing - information printed on the back of a picture by the photofinisher. The system standard requires the printing of frame number, film cassette number and processing date automatically on the back of each Advanced Photo System print.

Back projection - projection system often used to create location backgrounds in the studio.

Bag bellows - short flexible sleeve used on large format cameras in place of normal bellows when short focal length lenses are employed.

Balance - placement of colors, light and dark masses, or large and small objects in a picture to create harmony and equilibrium.

Ball and socket - swiveling mount used to attach a camera to a tripod, consisting of a large ball joint designed to move in a cup.

Ballistic photography - photography of weapons, ammunition and projectiles usually used for analysis.

Barium sulfate - compound used in the manufacture of photographic printing paper to give bright white highlights in the final print.

Barn doors - accessory used on spotlights and flood lamps to control the direction of light and width of the beam.

Barrel distortion - one of the common lens aberrations, where straight lines at the edge of the field are caused to bend into the shape of a barrel.

Baryta - coating of barium sulfate applied as the foundation to fiber based printing papers.

Base - support for photographic emulsions. Available in a choice of materials, including paper, cellulose, triacetate, glass and estar.

Baseboard camera - portable large format camera with a folding base-board. Allows a limited use of camera movements. Also referred to as a field camera.

Base Exposure Time - initial exposure time used for making a "straight" print.

Base-relief - photographic image effect usually produced by printing from a negative and a positive sandwiched together in the enlarger, slightly out of register.

Batch numbers - set of numbers printed on packages of sensitive materials to indicate common production coating.

Beam splitter - mirror and prism system capable of partly reflecting, partly transmitting light.

Belitski's reducer - solution used as a chemical reducer for negatives. It consists of ferric potassium citrate or oxalate in an acid fixing solution.

Bellows - light tight, folding sleeve which can be fitted between the lens and the film plane.

Bellows shutter - obsolete shutter consisting of a pair of bellows that, when closed together, form a hemisphere enclosing the lens.

Between the lens shutter - shutter usually placed within the components of a compound lens close to the diaphragm.

Bichromate - refers to potassium bichromate or potassium dichromate, used for bleaching and as a sensitizer for gelatin.

Bi-concave lens - simple lens or lens shape within a compound lens, whose surfaces curve toward the optical center. Such a lens causes light rays to diverge.

Bi-convex lens - simple lens shape whose surfaces curve outward, away from the optical center. Such a lens causes light rays to converge.

Binocular vision - visual ability to determine three dimensions. Stereoscopic photography depends on the use of binocular vision.

Bi-pack - combination of two films, differently sensitized, but exposed as one.

Bi-refringence - splitting of light passing through certain kinds of crystals into two rays at polarized right angles to each other.

Bispheric lens - lens having different curvatures at the center and the edge, each of which forms part of a sphere. The different edge curvature brings the peripheral rays more closely to the same point of focus as the center rays.

Bitumen - hydro-carbon which hardens by the action of light. It was used by Joseph Nicephore Niepce to produce the worlds first photograph in the early 19th century.

Black silver - finely divided metallic silver formed from silver halides by exposure and development.

Bleach - chemical bath capable of rehalogenizing black metallic silver.

Bleaching - stage in most toning, reducing and color processing systems.

Bleach-out - method of producing line drawings from photographic images. The photographic is processed in the normal way, its outlines sketched, and the black metallic silver image is then bleached away to leave a drawn outline.

Bleed - term used to describe a picture with no borders, which has been printed to the edge of the paper.

Blocked up - a portion of an overexposed and/or overdeveloped negative so dense with silver halides that texture and detail in the subject are unclear.

Blocking out - method of painting selected areas of a negative with an opaque liquid on the non-emulsion side. Since light is unable to penetrate these areas they appear white on the final print.

Blotter - sheet or sheets of absorbent material made expressly for photographic prints. Wet prints dry flat and quickly when placed between blotters.

Blowup - enlargement; a print that is made larger than the negative or slide.

Blue print - alternative term for cyanotype.

Blue sensitive - sensitive to blue light only. All silver halides used in traditional black and white emulsions are sensitive to blue light, but early photographic materials had only this sensitivity.

Blur - unsharp image areas, created or caused by subject or camera movement, or by selective or inaccurate focusing.

Boom - adjustable metal arm, attached to a firm stand, on which lighting can be mounted. Some booms are also made to support cameras.

Borax - mild alkali used in fine grain developing solutions to speed up the action of the solution.

Border - edge of a photographic print - either left white, or printed black.

Boric acid - compound used in certain fixers to prolong shier hardening life.

Bounce light - light that is directed away from the subject toward a reflective surface.

Box camera - simplest type of camera manufactured, and first introduced by George Eastman in 1888. It consists of a simple, single element lens, a light tight box and a place for film in the back.

Bracketing - technique of shooting a number of pictures of the same subject and viewpoint at different levels of exposure.

Brightfield - method of illumination used in photomicrography which will show a specimen against a white or light background.

Brightline viewfinder - viewfinder in which the subject is outlined by a bright frame, apparently suspended in space. This may show parallax correction marks, or lines indicating the fields of view of different focal lengths.

Brightness range - subjective term describing the difference in illumination between the darkest and lightest areas of the subject.

Brilliance - intensity of light reflected from a surface. It is sometimes an alternative term for luminosity.

Broad lighting - portrait lighting in which the main light source illuminates the side of the face closes to the camera.

Brometching - obsolete, special method of producing a bromide print. The result acquired the texture of its support and appeared similar to an etching.

Bromide paper - most common type of photographic printing paper. It is coated with an emulsion of silver bromide to reproduce black & white images.

Bromoil process - old printing process invented in 1907, consisting of three stages. First, an enlargement is made on bromide paper and processed. Second, the silver image is removed in a bleacher which also modifies the gelatin so it will accept lithographic ink. Third, while still damp the gelatin is inked up by hand to create the image.

Brownie - trade name given to early Kodak box cameras.

Brush development - method of development in which developer is applied to the material with a brush or similar instrument.

BSI - abbreviation for British Standards Institute.

Bubble chamber photography - method of analyzing the paths of high-speed sub-atomic particles.

Buffer - chemical substance used to maintain the alkalinity of a developing solution, particularly in the presence of bromine which is produced during development.

Built-in meter - reflective light meter built directly into the camera so that exposures can be easily made for the cameras position.

Bulb - See B.

Bulk film - film purchased in long lengths. Used in a bulk camera back or with a bulk film loader.

Burning in - see Printing-in.

Butterfly lighting - lighting in which the main source of light is -placed high and directly in front of the subject.

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Photo Glossary - C

C-41 - Kodak's standard chemical process for developing color negative film.

Cable release - flexible cable used for firing a camera shutter. Particularly useful for slow shutter speeds and time exposures, when touching the camera may cause camera vibration and blurring of the image.

Cadmium sulfide cell (CdS) - photo-sensitive cell used in exposure meters. Fed by an electric current from a battery, its electrical resistance varies according to the amount of light it receives.

Callier effect - contrast effect in photographic printing caused by the scattering of directional light from an enlarger condenser system. The negative highlights are of high density and scatter more light with little or no scattering from negative shadow areas, which are of low density. This gives a print higher contrast than a contact print.

Calotype process - first negative/positive process, invented by W.H. Fox Talbot in 1839. Paper was coated with silver iodide and a solution of silver nitrate and gallic acid. After exposure the paper was developed in a silver nitrate solution.

Camera angles - various positions of the camera with respect to the subject being photographed, each giving a different viewpoint and perspective.

Camera lucida - lens and prism system through which a virtual image was seen, apparently appearing on the surface of the drawing paper.

Camera movements - mechanical systems most common on large format cameras which provide the facility for lens and film plane movement from a normal standard position.

Camera obscura - origin of the present day camera. In its simplest form it consisted of a darkened room with a small hole in one wall. Light rays could pass through the hole to transmit on to a screen, and inverted image of the scene outside. It was first mentioned by Aristotle in the 4th Century B.C. and developed through the centuries as an aid to drawing.

Camera shake - movement of the camera caused by an unsteady hold or support. It is a major cause of un-sharp pictures, especially with long focus lenses.

Canada balsam - liquid resin with a refractive index similar to glass. It is used for bonding elements in compound lenses.

Candela - unit which expresses the luminous intensity of a light source.

Candid pictures - unposed pictures of people and animals, often taken without the subject's knowledge. These usually appear more natural and relaxed than posed pictures.

Candle meter - also known as a lux and defined as the illumination measured on a surface at a distance of one meter from a light source of one international candle power.

Candle meter second - unit of illumination related to exposure time, more often referred to as one lux-second.

Capacitor - device that builds and stores electrical charges. Used in electronic flash and some forms of electronic shutters.

Capping shutter - extra shutter used in some medium format cameras or in conjunction with a group of extreme high speed shutters.

Carbon arc - see Arc lamp.

Carbon process - contact printing process, introduced in 1866, using tissue coated with pigmented gelatin. The paper was sensitized in potassium bichromate and contact printed behind a negative in sunlight.

Carbon tetrachloride - liquid used for removing grease and finger prints from negatives.

Carbro process - early color print process using an adaptation of the carbon printing process.

Carrier - frame that holds a negative flat for enlarging.

Carte-de-visite - portrait photograph on a mount about the size of a postcard. Introduced in 1854, carte-de-visite became a social craze in many countries during the 1860s.

Cartridge - quick loading film container. pre-packed and sealed by the manufacturer.

Cassette - light tight metal or plastic container holding measured lengths of 35mm or medium format film, which may be loaded straight into the camera.

Cast - overall bias toward one color in a color photograph.

Catadioptric lens - see Mirror lens.

Catchlight - reflection of a light source in the subjects eyes.

Cathode ray tube - evacuated bulb of glass containing pairs of plates between which electrodes pass.

Caustic potash - high alkaline used in high contrast developing solutions to promote vigorous development. Highly corrosive and poisonous.

Caustic soda - see Caustic potash.

CCD - electronic sensor used by all autofocus cameras, capable of detecting subject contrast.

CC filter - abbreviation for color compensating filter.CC filters are designed primarily for introducing or correcting color bias at the camera exposure stage.

Centigrade - scale of temperature in which the freezing point of water is equal to 0° and boiling point to 100° C.

Changing bag - opaque fabric bag, which is light tight and inside sensitive materials may be handled safely.

Characteristic curve - performance graph showing the relationship between exposure and density under known developing conditions. It can provide immediate comparative information on factors such as emulsion speed, fog level, and contrast effect. The study of photographic chemicals in this way is known as sensitometry.

Chemical focus - point at which a lens brings the actinic rays to focus. In a modern fully corrected lens, chemical and visual focus coincide.

Chemical fog - even, overall density on film or paper. It is exaggerated by over-development.

Chemical reducer - see Reducers.

Chemical vapor - method of exposing negatives in a closed container to a small amount of mercury of sulfur dioxide. After approximately 24 hours the film is developed normally. It produces interesting yet very inconsistent results.

Chiaroscuro - light and shade effect. The way in which objects can be emphasized by patches of light, or obscured by shadow.

Chlorhydroquinone - developing agent contained in warm tone developers.

Chloride paper - printing paper with a silver chloride emulsion. Much less sensitive than bromide paper. Mainly used for contact printing.

Chlorobromide paper - photographic paper coated with an emulsion made up of both silver chloride and silver bromide. Used for producing enlargements with a warm, slightly brownish-black image, especially if processed in a warm tone developer.

Chlorquinol - alternate term for chlorhydroquinone.

Chromatic aberration - inability of a lens to bring light from the same subject plane but of different wavelengths to a common plane of image or focus.

Chromaticity - objective measurement of the color of an object or light source.

Chromatype - early type of extremely slow paper used for contact printing.

Chrome alum - alternative term for potassium chromium sulfate.

Chromogenic development - process in which the oxidation products of development combine with color couplers to form dyes during processing.

Chromogenic materials - color photographic materials which form dyes during processing.

Chronocyclograph - photograph used for the analysis of complex cyclic movements.

Chronophotography - technique pioneered by Eadweard Muybridge, for recording objects in motion by taking photographs at regular intervals.

Cibachrome - color printing process that produces color prints directly from color slides.

CIE standard - system of standards adopted by the Commission Internationale de I'Eclairage, allowing accurate descriptions of colors.

Circle of confusion - disks of light on the image, formed by the lens from points of light in the subject. The smaller these disks are in the image the sharper it appears.

Clayden effect - desensitizing of an emulsion by means of exposure to a strong, brief flash of light.

Clearing agent - processing solution used to remove stains or to cancel out the effect of chemicals left on the sensitive material left from previous stages in the process.

Clearing time - length of time needed for a negative to clear in a fixing solution.

Clear-spot focusing - method of lens focusing achieved by examining the image through a transparent area in a specific plane.

Cliche-verre - designs painted on glass in varnish or oil paint, or scratched into the emulsion of a fogged and processed plate using an etching needle. The results are then printed or enlarged on photographic printing paper.

Click-stops - lens aperture controls using a series of bearings that click audibly into place at each numbered setting.

Clip test - short sample of film, cut from the main exposed roll, used to determine the appropriate development and/or fixing time.

Close-up - general term for an image of a close subject, i.e. filling the frame.

Close-up attachment - accessory that enables a camera to focus on subjects nearer than the lens normally allows.

Close-up lens - see Close-up attachment.

CMYK - abbreviation for cyan, magenta, yellow and black. It is the colors used in a four color printing process.

Coated lens - lens with air-glass surfaces which have been coated with magnesium fluoride to reduce lens flare.

Coherent light - light waves that vibrate with constant phase relationships. They can be produced by a laser or a combination of two prisms.

Coincidence rangefinder - see Rangefinder.

Cold cathode illumination - low temperature fluorescent light source common in many diffuser enlargers, which is inclined to reduce contrast and edge definition.

Cold colors - colors at the blue end of the spectrum that suggest a cool atmosphere.

Cold-light enlarger - enlarger using cold cathode illumination. A diffusion type of enlarger. These types of enlarger heads scatter the light more evenly across the surface of the negative. One advantage of the cold light head is that it can render more subtle tonal gradations and will minimize the effect of dust and scratches on the negative which are translated to the print.

Collage - composition employing various different materials combined with original artwork attached to some type of backing.

Collodion - soluble gun-cotton, dissolved in a mixture of ether and alcohol.

Collodion process - also known as "wet collodion" was invented by Frederick Scott Archer in 1851-52. It was a great improvement over the earlier calotype process because because of the large increase in speed gained by exposing the plate while still "wet", but it had the disadvantage of requiring bulky equipment.

Color balance - adjustment in color photographic processes ensuring that a neutral scale of gray tones is reproduced accurately.

Color balancing filters - filters used to balance color film with the color temperature of the light source and prevent the formation of color casts.

Color circle - chart of spectrum hues presented as a circle.

Color compensatory filters - pale colored filters used to warm or cool subject colors.

Color contrast - subjective judgment on the apparent luminous difference or intensity of two colors when placed close to one another.

Color conversion filter - see CC filters.

Color developer - developer designed to reduce exposed silver halides of black silver and at the same time create oxidation byproducts that will react with color couplers to form specific dyes.

Color development - chemical treatment in the color processing cycle that produces the colored dye image.

Color head - enlarger illumination system that has built-in adjustable filters for color printing.

Color masking - pink or orange mask built into color negative film to improve final reproduction on the print.

Color mixing - practical application of either additive or subtractive color synthesis.

Color Negative - film designed to produce color image with both tones and colors reversed for subsequent printing to a positive image, usually on paper.

Color reversal - film designed to produce a normal color positive image on the film exposed in the camera for subsequent viewing by transmitted light.

Color saturation - purity or strength of color, due to the absence of black, white or gray.

Color sensitivity - response of a sensitive material to colors of different wavelengths.

Color sensitometry - method of determining the sensitivity of color materials.

Color separation - process of photographic an image through filters to produce three black and white negatives that represent red, green and blue content.

Color synthesis - combinations of colored light or dye layers that will collectively produce a colored image.

Color temperature - way of expressing the color quality of a light source. The color temperature is measured in Kelvin (K).

Color temperature meter - device for measuring the color temperature of a light source.

Color toning - system of changing the color of a black and white photograph by converting black metallic silver into a colored compound.

Color weight - visual characteristic of fully saturated colors. Some of these colors appear darker than others. A color's visual weight may have a different appearance to the eye to its appearance on film.

Coma - lens aberration producing asymmetrical distortion of points in the image.

Combination printing - producing a composite image by printing more than one negative on a single sheet of paper.

Compact camera - camera designed to allow easy portability or concealment.

Compensating developer - developer designed to compress the general contrast range in a negative without influencing gradation in the shadow and highlight areas.

Compensating positive - image on translucent material that can be printed together with the negative of the same image. When combined the result makes printing contrasty negatives easier.

Complementary color - color of light which, when combined with another specified color in the correct proportions, will form gray or white.

Completion - state of development when all the exposed silver halides have been reduced to metallic silver, and the image density will not increase with further development.

Composite printing - alternative term for combination printing.

Composition - visual arrangement of all the elements in a photograph.

Compound lens - lens system consisting of two or more elements. Compound lens designs can allow the lens designer to reduce lens aberrations, making maximum apertures larger and improve resolution.

Compound shutter - shutter consisting of a number of metal leaves arranged symmetrically around the edge of the lens barrel.

Compur shutter - well known German brand of compound shutter.

Concave lens - see Bi-concave lens.

Condenser - optical system which concentrates light rays from a wide source into a narrow beam. Condensers are used in spotlights and enlargers.

Condenser enlarger - enlarger with a sharp, undiffused light that produces high contrast and high definition in a print.

Cones - sensory organs on the retina of the eye, allowing color vision.

Constructivism - art movement that begun in Russia c. 1913. Characterized by the use of everyday materials in abstract compositions.

Contact paper - printing paper used only for contact printing. It is usually coated with a silver chloride emulsion of very slow speed.

Contact print - negative sized photograph made by exposing printing paper in direct contact with the negative.

Contact printer - apparatus used for making contact prints. Equipment ranges from a contact printing frame to more sophisticated boxes with safe lighting.

Contact screen - type of half-tone screen in which the dots consist of slightly unsharp halos. Used to make half-tone images.

Contamination - traces of chemicals that are present where they don't belong.

Continuous tone - term applied to monochrome negatives and prints, where the image contains a gradation of density from white through gray to black, which represents a variety of subject luminosities.

Contour film - special print film producing a equidensity line image from a continuous tone negative or print.

Contrast - subjective judgment of the difference between densities or luminosities and their degree of tonal separation in a subject, negative or positive print.

Contrast filters - filters used in black and white photography to darken or lighten the films rendition of particular colors in the subject.

Contrast grade - numbers (usually 1-5) and names (soft, medium, hard, extra-hard, and ultra hard) of the contrast grades of photographic papers.

Contrast values - perceived difference between the light areas (highlights) and the dark areas (shadows) of a scene. The range of contrast levels between the highlights and the shadows is called Contrast Values.

Contrasty - negative, print or scene with great differences between the highlights and shadows.

Contre-jour - backlighting. A photograph taken with the camera pointed directly at the light source.

Converging lens - see Convex lens.

Convertible lens - compound lens made in two sections, the elements of which are arranged so that when one part is unscrewed it provides a new lens with approximately twice the original focal length.

Convex lens - simple lens which causes rays of light from a subject to converge and form an image.

Cooke triplet - one of the most important lenses in lens history, designed by H.D. Taylor in 1893. It consists of three basic elements and has a maximum aperture of 16.3. It is the basic design that most normal focal length lenses of today have evolved.

Copper chloride - chemical contained in certain bleaches, toners, intensifiers, and reducers.

Copper sulfate - chemical contained in certain bleaches, toners, intensifiers, and reducers.

Copper toning - chemical process used for toning monochrome prints. See Toners.

Copyright laws - laws which govern the legality of ownership of a particular photographer or piece of work.

Correction filter - filter which alters the color rendition of a scene to suit the color response of the eye.

Coupled rangefinder - system of lens focusing which combines the rangefinder and the focusing mechanism, so that the lens is automatically focused as the rangefinder is adjusted.

Coupler - chemical present in different forms in all three layers of substantive color or a chemical incorporated into a developer.

Covering power - maximum area of image of usable quality, which a lens will produce.

Coving - plain curved background which has no edges, corners or folds and gives the impression of infinity.

CP filters - abbreviation for color printing filters.

C-print - any enlargement from a color negative.

Critical aperture - setting at which a lens gives its best performance. The setting offers the best compromise between diffracting due to small aperture and lens aberrations apparent at wide apertures.

Cronographic camera - camera used to photograph the sun.

Cropping - omitting parts of an image when making a print or copy negative in order to improve the composition of the final image.

Crossed polarization - system of using two polarizing filters, one over the light source and one between the subject and the lens. With certain materials crossed polarization causes bi-refringent effects which are exhibited as colored bands. Used in investigations of stress areas in engineering and architectural models.

Cross front - camera movement which allows the lens to be moved laterally from its original position.

Crown glass - low dispersion optical glass.

Cubism - early twentieth century European art movement characterized by the rendering of forms as simplified planes, lines and geometric shapes.

Curvilinear distortion - combination of barrel distortion and pincushion distortion.

Curvature of field - lens aberration causing a curved plane of focus.

Cut film - negative film available in flat sheets. The most common sizes are 4x5, and 8x10 inches.

Cyan - blue-green subtractive primary color which absorbs red and transmits blue-green.

Cyanotype - contact printing process producing a blue image on a white background.

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Photo Glossary - D

Daguerreotype - first practical and commercial photographic process, introduced by Louis Daguerre in 1839. The sensitive material comprised silver iodide, deposited on a polished silver plated copper base. A positive image was produced by camera exposure and mercury "development", which turned light struck halides gray-white. The image was made permanent by immersing the plate in a solution of sodium chloride.

Darkcloth - cloth made of dark material placed over the photographers head and the camera back to facilitate the viewing of images on the ground glass screen of sheet film cameras.

Darkfield - method of illumination used in photomicography that will show a specimen against a dark or black background.

Darkroom - light tight room used for processing and printing. It usually incorporates safe lighting suitable for the materials in use.

Darkslide - slide-in plastic sheet used on sheet film cameras over the front of the film holder to protect the emulsion from light.

Daylight enlarger - early type of enlarger using light from a hole in a window to provide illumination of the negative.

Daylight color film - color film intended for use with daylight or a light source of similar temperature. The film is color balanced to 5400 K.

Daylight tank - light tight container for film processing.

Dedicated flash - flash gun designed to integrate automatically into a cameras exposure reading and shutter circuitry.

Definition - subjective term for the clarity of a negative or print.

Delayed action - operation of the shutter some time after the release is depressed. Most shutters have a delayed action timer built in.

Dense - describes a negative or an area of a negative in which a large amount of silver has been deposited.

Densitometer - instrument for measuring the density of silver deposits on a developed image by transmitted or reflected light.

Density - amount of silver deposit produced by exposure and development. It is measured in terms of the logarithm of opacity, where opacity is the light stopping power of a medium.

Depth of field - distance between the nearest point and the farthest point in the subject which is perceived as acceptable sharp along a common image plane.

Depth of field scale - scale on a lens barrel showing the near and far limits of depth of field possible when the lens is set at any particular focus and aperture.

Depth of focus - distance which the film plane can be moved while maintaining an acceptably sharp image without refocusing the lens.

Desensitizing - reducing an exposed emulsion's sensitivity to light. This can be done by the application of dyes or by using oxidation agents.

Detective camera - popular Victorian camera which was designed to appear as a bowler hat, pocket watch or binoculars.

Developer - chemical bath containing reducing agents, which converts exposed silver halides to black metallic silver, making the latent image visible.

Development - process of converting exposed silver halides to a visible image.

Diaphragm - term used to describe the adjustable aperture of a lens. It controls the amount of light passing into the camera and may be in front of, within or behind the lens.

Diaphragm shutter - between the lens camera shutter that performs the function of the iris diaphragm.

Diapositive - positive image produced on a transparent support for viewing by transmitted light, i.e. transparency.

Diazo - abbreviation of diazonium compounds, which decompose under the action of intense blue or ultraviolet radiation, forming an image in an azo dye.

Dichroic - displaying two colors - one by transmitted and one by reflected light.

Dichroic filters - produced by metallic surface coatings on glass to form colors by interference of light. Used in high quality color enlarger heads.

Dichroic fog - purple-green bloom usually seen on negatives and caused by the formation of silver in the presence of an acid.

Differential focusing - setting the camera controls to produce minimum depth of field, so that image sharpness is limited to a particular subject element.

Diffraction - light rays scattered and change direction when they are passed through a small hole or close to an opaque surface.

Diffraction grating - optical attachment that separates light into its constituent colors.

Diffuse lighting - lighting that is low or moderate in contrast, such as on an overcast day.

Diffuser - any material that can scatter or diffuse light. The effect is to soften the character of light. The closer a diffuser is to a light source the less it scatters light.

Diffusing - process of softening detail in a print with a diffusion disk or other material that scatters light.

Diffusion condenser enlarger - enlarger that combines diffuse light with a condenser system, producing more contrast and sharper detail than a diffusion enlarger but less contrast than a condenser enlarger.

Diffusion enlarger - enlarger that scatters light before it strikes the negative, distributing light evenly on the negative. Detail is not as sharp as with a condenser enlarger.

Dilution - reduction in the strength of a liquid by mixing it with an appropriate quantity of water.

Dimensional stability - substance's ability to remain unchanging in size when subjected to processing and drying.

DIN - Deutsche Industrie Norm (German Standards Organization).

DIN speed - system used by the German Standards Organization.

Diopter - unit used to express the power of a lens. It is the reciprocal of the focal length expressed in meters.

Direct vision viewfinder - sighting device with which the subject is viewed directly, without the aid of a prism or mirror.

Discharge lamp - light source that provides illumination when an electrical charge is applied to gas particles in a glass tube. An example of this device is electronic flash.

Dish development - method of development used for processing single sheet, cut film or paper by immersing in a shallow dish of developer and agitating by rocking the dish.

Dispersion - ability of glass to bend light rays of deferent wavelengths to varying degrees.

Distance symbols - symbols used on the focus control of simple cameras, as a focusing guide.

Distortion - alteration in shape and/or proportions of an image.

Diverging lens - lens which causes rays of light coming from the subject to bend away from the optical axis.

Documentary photography - taking of photographs to provide a record of social and political situations with the aim of conveying information.

Dodging - control of exposure in photographic printing achieved by reducing exposure to specific areas of the paper.

Dolly - frame with lockable wheels, designed to support s tripod, and allow easy movement around a studio.

Double exposure - see Multiple exposure.

Double extension - characteristic of large format cameras which enables the bellows to be extended to twice that of the focal length of the lens in use. It is used for close-up photography.-

Drop-in-loading - feature in all Advanced Photo System cameras that virtually eliminates film-loading problems by automatically accepting the leader less cassette.

Dry down - refers to the amount a print darkens after drying.

Drying cabinet - vented cabinet equipped with suspension clips for drying films.

Drying marks - marks on the film emulsion caused by uneven drying and resulting in areas of uneven density, which may show up in the final print.

Dry mounting - method of attaching prints to mounting surfaces by heating shellac tissue between the mount and the print.

Dry plates - term used to describe gelatin coated plates in the days when wet collodion process was still popular.

DX coding - method, whereby films can automatically set the film ISO speed.

Dyad - pair of complementary colors or any two colors considered visually harmonious.

Dye coupling - process creating a colored image from the reaction between by-products of color development and couplers.

Dye destruction process - method of producing a colored image by partially bleaching fully formed dye layers incorporated in the sensitive material.

Dye-image monochrome films - black & white negative films designed for color processing.

Dye sensitizing - defined as all silver halides used in black & white emulsions are sensitive to blue light. Early photographic materials possessed only this sensitivity.

Dye transfer print - method of producing color prints via three color separation negatives. Negatives are used to make positive matrixes, which are dyed in subtractive primaries and printed in register.

Dynamism - picture structuring which relates to a sense of movement and action.

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Photo Glossary - E

E6 - Kodak's standard chemical process for developing Ektachrome or compatible slide films.

Easel - device to hold photographic paper flat during exposure, usually equipped with an adjustable metal mask for framing.

Eberhard effect - border effect occurring in a developed image. It appears as a dense line along an edge of high density and as a light line along an edge of low density. It occurs most often in plates developed flat in solution that is not sufficiently agitated. The effect was described by Gistav Eberhard in 1926.

Edge numbers - reference numbers printed by light at regular intervals along the edge of 35mm and roll films during manufacture.

Effective aperture - diameter of the bundle of light rays striking the first lens element that actually pass through the lens at any given diaphragm setting.

EIS - Electronic Image Stabilizer. A feature that minimizes effect of camera shake.

Electroluminescence - conversion of electric energy directly into visible light.

Electronic flash - artificial lighting produced by an electronic discharge in a gas filled tube. A single tube can produce a large number of flashes.

Electronic shutter - shutter system timed by electronic rather than mechanical means.

Electrophotography - creation of images by alteration to the electrical properties of the sensitive material as a result of the action of light.

Element - single lens shaped piece of glass that forms part of a compound lens system.

Elon - another term for Methylaminophenol sulfate. It is more commonly known as metol.

Emulsion - light sensitive material which consists of a suspension of silver halides in gelatin.

Emulsion side - side of the film coated with emulsion.

Endoscope - optical device allowing the viewing and photography of small inaccessible subjects.

Enhanced back printing - Advanced Photo System feature available in some cameras that enables users to encode detailed information at the time of picture-taking.

Enlargement - term used to describe a print larger than the negative used to produce it.

Enlargement ratio - ratio denoting the amount of linear (not area) enlargement between a print and the negative from which it is made.

Enlarger - apparatus for producing prints by projecting a negative or transparency on sensitive paper.

Enprint - small enlarged print, with dimensions of a fixed ration, produced commercially in an automatic printer. Usually 3 ½" wide.

Entrance pupil - size of the beam of light which, entering the elements of a compound lens that are in front of the aperture, completely fills the iris diaphragm.

Equivalent focal length - distance in a lens between the front nodal point and the focal plane when the lens is set to focus a subject at infinity. In a telephoto lens the equivalent focal length is shorter than the back focus. The reverse is true in a wide angle lens.

Etch - process of removing small imperfections in a print or negative by scraping away part of the emulsion.

Etching - dissolving away selected areas of a surface while shielding the other portions with a resistant. The process is used as a creative drawing medium as well as for making half-tone plates on copper or zinc.

Ever-ready case - camera case that can be opened, allowing the camera to be used without removing it. A front flap hinges down to uncover the lens, viewfinder and camera controls.

Everset shutter - simple camera shutter mechanism on which a single depression of the release both tensions and fires the shutter.

Exit pupil - image of the iris diaphragm formed on the back surface of a compound lens by the elements behind the aperture.

Expiry date - date stamp on most film boxes indicating the useful life of the material in terms of maintaining its published speed and contrast.

Exposure - product of the intensity of light and the time the light is allowed to act on the emulsion (I x T = E).

Exposure index - see Speed.

Exposure latitude - amount by which it is possible to over or underexpose a light sensitive material and, with standard processing, still produce acceptable results.

Exposure meter - instrument for measuring the amount of light falling on or being reflected by a subject.

Exposure value (EV) - scale of values used to indicate the sensitivity range of a TTL or off-camera meter system within which accurate exposure measurement is guaranteed.

Extension bellows - device used to provide the additional separation between lens and film required for close-up photography.

Extension tubes - metal or plastic tubes used on small format cameras, to extend lens-to-film distance, enabling magnification greater than 1x.

Extinction meter - early type of exposure calculator.

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Photo Glossary - F
Factor - number that tells how many times exposure must be increased in order to compensate from loss of light.

Fahrenheit scale - scale of temperature named after its German originator, G. D. Fahrenheit. On this scale, the freezing point of water is 32° F, and the boiling point of water is 212° F.

False attachment - part of one object seen behind another so that lines, shapes or tones seem to join up. A composition device used in various ways to produce images in which foreground and background objects appear to occupy the same plane.

Farmer's reducer - used for bleaching negatives and prints. (See reducers)

Farraday shutter - high-speed shutter using a pair of crossed polarizers, between which is a glass block within a coil. When a voltage passes through the coil, the plane of polarization changes, allowing light to pass through the second polarizer.

Fast film - film which has an emulsion that is very sensitive to light. These films have high ISO ratings.

Fast lens - lens with a wide maximum aperture (low f number).

Ferric chloride - bleaching solution used on negative materials.

Ferrotype process - method of creating direct positive images with dark enameled metal plates as a base. Also known as the tin-type process.

Fiber based paper - photographic paper without a resin coating. Processing times are longer than for other papers, but the paper is more archivally permanent.

Field camera - sheet film camera suitable for use in location work.

Fill-in - light used to illuminate the shadow areas of a scene.

Fill light - source of illumination that lightens shadows. See Fill-in.

Film - photographic material consisting of a thin transparent plastic base coated with a light sensitive emulsion.

Film characteristic curve - describes a graphical relationship between the logarithm of the exposure value (horizontal axis) and density (vertical axis) of film. Each brand of film exhibits a different characteristic curve.

Film clips - metal or plastic clips used to prevent the curling of a length of drying film.

Film holder - light tight container to hold sheet film.

Film pack - container holding several sheets of film, so devised that when fitted to the camera the photographer can pull a tab to remove an exposed sheet and replace it with another. Film packs are typical with Polaroid film.

Film plane - plane at the back of the camera across which the film lies.

Film speed - see Speed.

Filter factor - number by which an unfiltered exposure reading must be multiplied to give the same effective exposure through the filter. This compensates for the absorption of light by the filter. This process is unnecessary with TTL metering systems as long as the filter is attached during the metering process.

Filters - colored glass, gelatin or plastic disks, which modify the light passing through them, mainly in terms of color content. They can be used at the camera or printing stages.

Finality development - prolonged development, reducing silver halides affected by light to silver until no further image density improvement occurs.

Finder - abbreviation for viewfinder.

Fine grain developers - film developers which help to keep grain size in the photographic image to a minimum.

Fisheye lens - extreme wide-angle lens with an angle of view exceeding 100° and sometimes in excess of 180°. Depth of field is practically infinite and focusing is not required.

Fixation - chemical bath which converts unused halides to a soluble silver complex in both negatives and prints, making the image stable in white light.

Fixed focal length - camera system whose lens cannot be interchanged for a lens of different focal length.

Fixed focus - lens camera system that has no method of focusing on a fixed point, usually at the hyperfocal distance.

Fixer - chemical solution used for fixation.

Flare - non-image forming light scattered by the lens or reflected from the camera interior.

Flash - artificial light source giving brief but very bright illumination. It is produced by a combination of certain gases within a transparent tube. There are two types; electronic, which may be used repeatedly, and expendable in which the bulb can be used only once.

Flash bulb - replaceable bulb for use in expendable flash units. A glass bulb contains a pyrotechnic wire or paste which burns out in a brilliant flash when a low voltage firing current is applied.

Flash cube - obsolete bulb containing four small flash bulbs built into a single unit.

Flash factor - number which provides a guide to correct exposure when using flash. See also Guide number.

Flashing - briefly and evenly exposing photographic materials to white light.Often used to lower contrast of printing paper, when the flashing exposure is made in addition to the regular exposure.

Flash powder - chemical powder consisting of a mixture of metallic magnesium and an oxidizing agent. Ignited by heat to produce a brilliant flash of light.

Flash synchronization - method of synchronizing flash light duration with maximum shutter opening. There are usually two settings on a camera, X and M. X is the setting used for electronic flash. M is for most expendable types of flash (bulbs) which require a delay in shutter opening.

Flat - used to describe a negative or print with very low contrast.

Flat-bed camera - camera designed for copying artwork and documents. Mounted on a vertical column, like an enlarger, allowing the photographer to accommodate different documents or artwork for duplication.

Flat gradation - subjective term used to describe low-contrast values.

Flat lighting - lighting that produces very little contrast or modeling on the subject and a minimum of shadows.

Floating elements - one or more elements in a lens which adjust position relative to other components during focusing or zooming. Used to maintain correction of lens aberrations at all settings.

Floodlight - artificial light source with a dish shaped reflector and a 125-500+ watt tungsten filament lamp producing evenly spread illumination over the subject.

Fluorescent whites - brilliant highlights produced by applying a fluorescent agent to a printing paper base. The print can also be treated after washing with a fluorescent whitener or dye solution.

f numbers -e numbers on the lens barrel indicating the size of the aperture relative to the focal length of the lens. f numbers are calculated by dividing the focal length of the lens by the effective diameter of the aperture.

Focal length - distance between the rear nodal point of the lens and the focal plane, when the focus is at infinity.

Focal plane - imaginary line perpendicular to the optical axis which passes through the focal point. It forms the plane of sharp focus when the lens is set at infinity

Focal plane shutter - shutter which lies just in front of the focal plane. Light sensitive film positioned at the focal plane is progressively exposed as the shutter blinds move across it.

Focal point - point of light on the optical axis where all rays of light from a given subject meet at a common point of sharp focus.

Focus - position in which rays of light from a lens converge to form a sharp image.

Focusing - system of moving the lens in relation to the image plane so as to obtain the required degree of sharpness of the film.

Focusing cloth - dark cloth used in view camera photography.

Focusing hood - light proof cowl used on TLR and most roll film SLR cameras to prevent extraneous light falling on the focusing screen.

Focusing magnifier - device to magnify the optical image and aid visual focusing.

Focusing scale - scale of distances marked on a lens focusing ring.

Focusing screen - ground glass screen fixed to the camera at the image-forming plane, enabling the image to be viewed and focused.

Focus range - range within which a camera is able to focus on the selected picture subject.

Fogging (Fog) - produces an overall veil of density on a negative or print, which does not form part of the image. It can be achieved by chemicals or exposing the sensitive material to light.

Fog level - density formed in unexposed areas of film or paper during processing.

Foreground - area in an image closer than the main subject.

Format - size of negative paper or camera viewing area.

Frame
1. single exposure on a roll of film.
2. viewfinder image boundary.
3. Decorative border applied to finished, mounted prints.

Frames per second (fps) - used to describe how many frames can a motor drive or winder handle automatically.

Free working distance - distance between the front of the lens and the subject.

Fresnel lens - condenser lens used on a spotlight to gather together the rays of light coming from a source and direct them into a narrow beam.

Fresnel magnifier - condenser lens used at the center of some ground glass viewing screens to aid focusing.

Frilling - wrinkling and separation of the emulsion along the edges of its support material.

Front curtain synchronization - when the flash fires an instant after the front curtain of a focal plane shutter has completed its travel across the film plane.

Front element focusing - system of lens focusing in which only the front component of a compound lens moves backward and forward to adjust focus.

Front projection - method of projection which allows you to combine a figure in a studio with a previously photographed background scene. The image is projected from the camera position onto a special reflective background screen.

F stop - number that equals the focal length of the lens divided by the diameter of the aperture.

Full scale print - print having a wide range of tonalities.

Futurism - art movement started in Italy c. 1910, characterized by an aggressive rejection of tradition, and the representation of the dynamic movement of machinery.

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Photo Glossary - G
Galvanography - technique of electroplating a gelatin relief image created photographically to produce a photomechanical printing plate.

Gamma - measurement used in sensitometry to describe the angle made between the straight line portion of the characteristic curve of the photograph emulsion and the base of the graph. The gamma is the tangent of the angle so formed.

G curve - average gradient of a characteristic curve, describing similar characteristics to gamma, but measuring the slope from a line joining the lower and upper limits of the curve actually used in practice.

Gelatin - natural protein used as a transparent medium to hold light sensitive silver halide crystals in suspension, binding them to the printing paper or film, yet swelling to allow entry of processing solutions.

Gelatin filters - filters cut from dyed gelatin sheets and held in front of the lens or studio light.

Gelatin sugar process - daylight printing process using paper with a sugar and dichromate coating, which hardens on exposure to light.

Ghost images - bright spots of light, often taking the shape of the aperture, which appear in the camera viewfinder or in the final photograph when a lens is pointed at a bright light like the sun. Ghost images have been almost eliminated through the use of multi layer coatings of the lens elements.

Glaze - glossy surface produced on some (non resin coated) printing papers. It is achieved by placing a wet print to to a heated drum or clean polished surface. Glazed print produce denser medium blacks than their matte counterparts.

Glazer - machine on which wet fiber base prints are placed face down in contact with a polished surface, such a chromed steel, and held by tension. The surface is then heated to dry the print.

Glossy paper - printing paper with a smooth shiny surface finish to give maximum detail and tonal range.

Gold chloride - soluble chemical used in gold toners.

Gold mean - compositional technique used to determine the "ideal" position of the main subject in the frame. It is based on creating a rectangle from a square. A line drawn from the center of one side of the square to the opposite corner becomes the radius of an arc. The side of the square is then protracted until it meets the arc, and from this point a rectangle is constructed. The side of the square which remains in the rectangle indicates the point at which the subject should be placed.

GOST - arithmetical system of rating film speed used in Soviet bloc countries.

Graduated filter - filter with a colored section, which gradually reduces in density toward the center of the filter. The rest of the filter is clear. Also referred to as a Graduated filter

Gradation - tonal contrast range of an image.

Grade - system of terms and numbers used to denote the contrast characteristics of black and white printing papers.

Graduate - vessel used for measuring liquids.

Grain - clumps of silver-halide grains in film and paper that constitute the image. These grains are produced both in the exposure process (film grain) and in the development process (paper grain). Unlike film, the grain in printing paper is largely responsible for the image tone.

Graininess - clumps of silver halide crystals in the emulsion which are visible to the human eye because of spaces between the crystals.

Grains - exposed and developed silver halides which have formed black metallic silver grains, producing the visible photographic image.

Granularity - objective term describing the amount that silver halide grains have clumped together within the emulsion.

Gray card - card with an 18 percent gray tint (reflectance) used to determine exposure by taking a meter reading from subject light reflected by the card.

Ground glass screen - translucent glass sheet used for viewing and focusing the image on all large format and some reflex cameras.

Guide number - term sometimes used to describe a flash factor, which provides a guide to correct exposure when using flash.

Gum arabic - water soluble gum obtained from the Acacia tree and used in coatings of a number of photographic processes.

Gum bichromate - contact printing process once very popular for the manipulative, impressionistic effects it makes possible. Drawing paper is coated with a mixture of gum, potassium bichromate and a pigment of any chosen color. This is then exposed to light behind a negative. Also known as the photo aquatint process.

Gum platinum process - combination of gum and platinum printing.

Gyroscopic camera mount - device employing a gyroscope to help stabilize hand held cameras subject to movement or vibration from outside sources.

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Photo Glossary - H
Halation - diffused ring of light typically formed around small brilliant highlight areas in the subject. It is caused by light passing straight through the emulsion and being reflected back by the film base on the light sensitive layer. This records slightly out of register with the original image.

Halogens -a group of chemical elements. In photography, three of these, bromine, chlorine and iodine are used with silver to produce light sensitive material.

Half-frame - negative format of 18 x 24mm. Images are recorded on a vertical axis on standard 35mm film, thus giving 72 half-frame images on film designed for 36 exposures.

Half-frame camera - camera designed to use 35mm film in a half-frame format.

Half-plate - picture format measuring 4 ¾ x 6 ½ inches. Some early cameras produced negatives of this size.

Half-silvered mirror is a glass sheet evenly coated with a substance which transmits part of the light incident on it and reflects the remainder. Used for beam splitting devices in holography, and for front projection.

Halftone - mechanical process for printing continuous tone images in ink.

Halogens - collective term for the elements chlorine, bromine and iodine, which are combined with silver to produce the light sensitive crystals used as the basis for photographic emulsions.

Hand coloring - process of applying color tints, in the form of paint, to a photographic image to create or enhance the color effect.

Hanger - frame for holding sheet film for processing.

Hard - defines a scene, negative or print with high contrast.

Hardeners - chemicals often used with a fixing bath to strengthen the physical characteristics of an emulsion. The most common hardeners are potassium or chrome alum.

Hard gradation - term denoting the quality of harsh contrast in a photograph.

Heat filter - optical attachment made of thick infrared absorbing glass, used to absorb heat radiation from alight source without diminishing output.

Heliography - early photographic process invented by Niepce, employing a polished pewter plate coated with bitumen of Judea.

Herschel effect - the destruction of an exposed image by infrared radiation.

Hide - camouflaged barrier used by natural history and wildlife photographers.

High art photography - general term for an early form of artistic photography (1851-1870), in which photographers set out to match the style and subject matter of paintings of the period.

High contrast developer - solutions used to produce high contrast images.

High key - photograph which contains large areas of light tones, with few middle tomes or shadows.

Highlights - the brightest ares of the subject, represented on a negative by dense deposits of black metallic silver, but reproducing as bright areas on the positive print.

Hill cloud lens - lens with a 180° angle of view, used for photographing cloud formations and other meteorological work.

Holding back - 1. Shortening the development time given to film to help reduce image contrast. 2. Method of decreasing exposure given to selective areas of the print. Also referred to as dodging.

Holography - system of photography, using neither a camera not lens, in which laser beams create an interference patter recorded directly on appropriate light sensitive sheet film or plates. After processing, viewing the image by the light of a laser gives a three dimensional image.

Horizon - line at which earth and sky appear to meet. Its position, which can be altered by titling the camera or by cropping the image determines whether the sky or the landscape concentrates interest in the picture. A low horizon (tilting the camera up) concentrates interest in the sky while a high horizon (tilting the camera down) concentrates interest in the landscape.

Hot shoe - fitting on the top of many cameras designed to hold accessories, such as a flash gun.

Hot spot - often undesirable concentration of the central beam of a flood or spotlight on the subject.

Hue - name of the color (e.g. red, blue, yellow).

Hydrobromic acid - acid liberated during the developing process by the reduction of bromide.

Hydrochloric acid - chemical used in some bleaching solutions.

Hydrogen peroxide - chemical used in hypo clearing agents.

Hydroquinone - reducing agent. It is used in developers to provide high contrast results in the presence of a strong alkali.

Hyperfocal distance - distance between the camera and the hyperfocal point.

Hyperfocal point - nearest point to the camera which is considered acceptably sharp when the lens is focused on infinity. When a lens is focused on the hyperfocal point, depth of field extends from a distance halfway between this point and the camera to infinity.

Hypersensitizing - method of increasing the light sensitivity of a photographic emulsion prior to exposure.

Hypo - common name for a fixing agent, derived from an abbreviation of hyposulfite of soda, the misnomer applied to sodium thiosulfate during the 19th century.

Hypo eliminator - chemical bath which removes traces of fixing agent from an emulsion.

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Photo Glossary - I

"Ideal" format - film format in the proportion of 4 to 3, e.g. 6 x 4.5cm. This ratio is considered the ideal shape by some manufacturers and many photographers for both vertical and horizontal composition.

IF (Internal Focusing) - system in which only the internal lens group shifts during focusing. IF benefits include focusing without changing the physical length of a lens body, faster focusing, reduced diameter of the focusing ring, closer minimum focusing distance, and aberrations corrected throughout the entire focusing distance range.

Illuminance - term quantifying the illumination of, or incident light falling on a surface.

Image - two dimensional representation of a real object, produced by focusing rays of light.

Image plane - plane commonly at right angles to the optical axis at which a sharp image of the subject is formed. The nearer the subject is to the camera, the greater the lens image plane distance.

Impressionism - art movement in which painters broke away from the techniques of continuous brushstrokes and clearly expressed detail. They were largely concerned with the effects of light and color.

Incident light - light falling on a surface, as opposed to reflected by it.

Incident light attachment - accessory for a hand held exposure meter which allows it to give incident light readings. Many models come with this accessory permanently attached.

Incident light reading - measurement, by light meter, of the amount of incident light falling upon a subject. The light meter is placed close to the subject, pointing towards the main light source.

Indicator chemical - neutral chemical which can be added to a sample of a solution to indicate its pH level or the presence of hypo.

Infectious development - development action which occurs in processing "lith" materials. The oxidation of hydroquinone produces new and highly active reducing agents, semiquinones, in the presence of a low quantity of sodium sulfite. This results in a very high contrast image.

Infinity - in photographic terms is a distance great enough to be unaffected by finite variations. In practice this relates to most subjects beyond 1000 meters or, in landscape terms, the horizon.

Infrared - rays that occur beyond the red end of the electro-magnetic spectrum and are invisible to the human eye. They can be recorded on specially sensitized films, producing images in black & white or color.

Infrared compensation index - used to compensate the focus for black and white infrared film. Color IR film generally does not require compensation.

Infrared focus - see IR setting.

Instamatic camera - compact camera popular in the 1960s and 70s with very simple controls, taking 126 film and yielding a 28 x28 mm negative.

Instant picture camera - camera, usually with simple controls, producing a finished photographic print within minutes of the film being exposed, (e.g. Polaroid cameras and materials).

Integral tri-pack - three emulsions, usually of different character, coated on the same film base. The system is used mainly on color materials and also on some special purpose black & white materials.

Integrating - term used to describe a method of arriving at an exposure setting by taking an average of the light readings from the bright areas and the and the shadow areas of the subject.

Intensification - chemical method of increasing the density of the photographic image. It is only suitable for treating negative materials and works better on negatives that have been underdeveloped rather than underexposed.

Intensity scale - exposure scale in which the time of exposure remains constant but the intensity of light increases in regular stops.

Interchangeable lens system - system of lenses of different focal lengths made to fit the same camera body.

Interference - interaction of light waves when they meet and either reinforce or cancel each other (e.g. holograms).

Interleaving - method of agitating more than one sheet of photographic paper in the same tray of chemicals.

Intermittency effect - states that, a number of short, separate exposures will not produce the same photographic result when combined as a single exposure of equivalent total duration.

Internegative - negative made on special color film designed for making copy prints from color slides.

Intersection of thirds - compositional technique whereby the image area is divided horizontally and vertically into equal thirds by means of four imaginary lines. The main subject is considered strongly placed it it is positioned at the intersection of any two of these lines.

Interspersed aspect ratio - basic requirement of certified photofinishers and certified photo finishing equipment. It specifies the three APS system print formats - C, H and P.

Inverse square law - states that, when the light source is a point, illumination on a surface is inversely proportional to the square of the distance of the light source.

Inverted telephoto lens - lens construction which gives a short focal length with a long back focus or lens-film distance. It enable wide-angle lenses to be produced for small format cameras, where space is required for mirrors, shutters, etc.

Iodine - chemical used in reducers and bleachers.

Iris diaphragm - continuously adjustable lens aperture consisting of interposed metal leaves.

Irradiation - by the physical structure of the emulsion and the distribution of the silver halide grains cause rays of light to be scattered as they travel through the emulsion.

IR setting - mark usually in red, found on many camera lens mounts. It indicates the focus change required for infrared photography.

IS (Image Stabilizer) - feature that minimizes the effects of camera shake. Originally designed for video cameras. Canon has transferee the technology to its EF lenses.

I setting - mark found on some cheap box cameras which indicates an instantaneous shutter speed of approximately 1/50 second.

ISO - International Standards Organization. Used instead of ASA as prefix to film speeds. The scale is identical to the ASA scale.

Ivorytype - obsolete printing process designed to give the impression of a painting on ivory. A hand colored print was impregnated with wax and squeegeed face down on hot glass. The paper base was then back by ivory tinted paper.

IX (Information Exchange) - ability of APS film to communicate with devices, and devices to communicate with film.

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Photo Glossary - J

JCII - Japan Camera Inspection and Testing Institute. It is an organization in Japan to monitor export quality of Japanese made cameras.

JPEG - format for compressed graphics files. JPEG graphics are commonly used as part of World Wide Web.

Joule - unit used to quantify the light output of electronic flash. A joule is equal to one watt second of 40 lumen-seconds. The measure is used to compare flash units in terms of power output.

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Photo Glossary - K

K14 - Kodak's chemical process for developing Kodachrome slides.

Kallitype - obsolete printing process, resembling the platinum process. The image is formed in metallic silver rather than expensive platinum.

Kelvin (K) - unit of measurement on the absolute temperature scale, used to describe the color content of continuous spectrum light sources.

Kerr cell - high speed shutter without moving parts, using two crossed polarizing filters at either end of a cylinder filled with nitrobenzine.

Keyed emulsion sensitivity - term used to describe the color response of color printing papers which have peak sensitivities to the three dye colors present in the same manufacturers color negatives.

Key light - studio light used to control the tonal level of the main area of the subject.

Kilowatt - unit of 1000 watts. Used to measure the power of an electrical light source.

Kinetic - concerned with movement and motion.

Knifing - method of removing marks and other blemishes from the surface of a print by gentle scraping with the tip of a sharp knife.

Kostinsky effect - development effect in which dense image points are inclined to move apart, relative to each other, and light image points to move together, relative to each other. This occurs because developer is not being equally distributed over the image point and is rapidly exhausted when to heavily exposed image points are close together.

Kromskop - early viewing instrument invented by F.E. Ives, embodying a system of mirrors and color filters to synthesize a full color image. This enabled monochrome transparencies made from separation negatives to be rear-illuminated through blue, green and red filters, and then been seen combined in register as a single image.

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Photo Glossary - L

Lamp - general term used to describe the various kinds of artificial light sources used in photography.

Lamp black - pure carbon pigment, made from soot deposited from burning oils.

Lamp house - light tight housing of an enlarger or projector, which contains the light source.

Lantern slides - old term used to describe transparencies.

Large format camera - general term for any camera having a picture format of 4 x 5 inches or larger.

Laser - abbreviation for Light Amplification by Stimulated Emission of Radiation.

Latensification - method of increasing relative film speed by fogging after exposure and before development. It can be achieved by chemical or light means.

Latent image - invisible image produced by exposure which can be made visible by development.

Lateral reversal - mirror image reversal of the subject from left to right, as found in the viewfinders of some reflex cameras.

Latitude - degree by which exposure can be varied and still produce an acceptable image. The degree of latitude varies by film type. Faster films tend to have greater latitude than slower films.

LCD - liquid crystal diode. LCD is an electronic solid state display system commonly used for the face of wrist watches, and also used to display exposure information in the viewfinder of most modern day cameras. A surface can be temporarily changed from transparent to dense black by application of a charge. The LCD can be programmed to display any required black shape.

Lead acetate - crystalline, highly poisonous powder used in some toning and intensifying solutions.

Leader - beginning of a roll of film, which is attached to the camera's take up spool.

Leaf shutter - see Between the lens shutter.

LED - light emitting diode. LED is an indicator light used to convey exposure information.

Lens - optical element made of glass or plastic and capable of bending light. A lens may be constructed of single or multiple elements.

Lens barrel - metal or plastic tube with a blackened inner surface, in which the lens elements and mechanical components of the lens are mounted.

Lens cap - plastic, rubber or metal cover which fits over the front or back of the lens to protect it.

Lens coating - layer or multiple layers of thin anti-reflective materials applied to the surface of lens elements to reduce light reflection and increase the amount of transmitted light.

Lens drive system - used in autofocus SLR cameras. One type has a motor located inside the lens; in another, a motor inside the camera body turns the lens via a drive shaft.

Lens hood - opaque tube, either cylindrical, square of funnel shaped, use to shield a lens from stray light outside the field of view.

Lens shade - see Lens hood.

Lens shutter camera - camera with the shutter built into the lens.

Lens speed - largest lens opening (smallest f-number) at which a lens can be set. A fast lens transmits more light and has a larger opening than a slow lens. Determined by the maximum aperture of the lens in relation to its focal length. The speed of a lens is relative to it's focal length. A 400 mm lens with a maximum aperture of f/3.5 is considered extremely fast, while a 28mm f/3.5 lens is thought to be relatively slow.

Lens system - describes the type and quantity of lenses available for use with a particular camera.

Lenticular screen - lens system consisting of a screen containing a number of small lenses.There are two applications of lenticular systems. They are used in some exposure meters to gather light and to determine the angle of acceptance of light by the meter. A lenticular screen consisting of a number of lenses et into rows can be used at the camera stage to produce stereoscopic images by synthesizing binocular vision.

Light - visible radiated energy which forms part of the electro-magnetic spectrum in the wavelength range of 4000-7000 Å (400-720 nm).

Lightbox - box of fluorescent tubes balanced for white light and covered with translucent glass or plastic. Used for viewing, registering or correcting film negatives and positives.

Lighting ratio - ratio of the brightness of light falling on the subject from the main (key) light and other (fill) lights. A ratio of about 3:1 is normal for color photography.

Light meter - alternate term for exposure meter.

Light sources - general term applied to any source of light used in photography.

Light tent - tent like structure made of translucent material hung around a frame. The fabric diffuses the light coming from outside the tent so that highly reflective subjects placed inside the tent can be photographed without reflections.

Light-tight - term denoting a material or piece of equipment that is impervious to light.

Light trail - image track recorded on photographic material when a point of light is shifted during exposure.

Light trap - system of entry to a darkroom which allows easy access, but prevents unwanted light from entering.

Light value - alternative term for exposure value (EV).

Limiting aperture - actual size of the aperture formed by the iris diaphragm at any setting.

Linear perspective - apparent convergence of parallel lines with increasing distance in a two dimensional image.

Line film - high contrast film which, after correct development, gives negatives of black and white only (with no grays).

Line image - photographic image consisting of black areas and clear film i.e. white.

Linked Ring Brotherhood - group of pictorialist photographers who broke away from the Photographic Society of Great Britain. Existed between 1892-1910.

Lippman process - early color process invented by Professor Gabriel Lippmann (1845-1921). Light first passed through an almost transparent emulsion layer and was then reflected back by a layer of mercury. The interference between reflected and incident light produced a latent image in the emulsion which could be given b&w processing, but when backed with a mirror appeared in color.

Lith film - extreme form of line film, which produces very high contrast images when used in conjunction with a special lith developer.

Local control - method of controlling the final quality of a print by increasing or decreasing the exposure given to localized areas of the print by selective masking.

Log e - logarithmic value (to the base 10) of the relative brightness exposed on the film when undergoing sensitometric testing.

Long focus - a lens in which the focal length is much greater than the diagonal of the film format with which it is used.

Low key - photograph in which tones are predominantly dark and there are few highlights.

Lumen - unit of light intensity falling onto a surface.

Lumen second - unit to measure the total light output of a photographic source.

Luminance - measurable amount of light which is emitted by or reflected from a source.

Luminance meter - alternate term for exposure meter.

Luminescence - visible light produced from a surface submitted to invisible radiation such as UV, X rays and son on. Unlike fluorescent light it continues to be emitted after the existing source is removed, gradually fading away.

Luminosity - brightness of either a light source or a reflective surface.

Luminous flux - intensity of a light source, measured in lumens.

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Photo Glossary - M

Mackie line is an effect sometime found on a negative or print, in which a light line forms along the boundaries of the darkest image areas. It may also be caused during processing by the diffusion of exhausted developer, lack of agitation, or by solarization.

Macro attachment are supplementary elements attached to the front of a normal lens to give an extreme close-up facility.

Macro lens is a lens specially designed to give accurate resolution of a very near subject without the need for supplementary attachments. Sometimes, incorrectly, referred to as a micro lens.

Macrophotography is photography which produces an image larger than the original subject size without the use of a microscope.

Magazine is a light-tight container holding roll film.

Magenta is the complimentary color to green. It is composed of blue and red light.

Magnification is the size of the image relative to the size of the subject used to produce it. It is an expression of the ratio of the subject-lens distance to the image-lens distance. When object distance = image distance, magnification = 1.

Magnification ratio see Magnification.

Main light see Key light.

Mask is an opaque material used to cover the edges of the printing paper, and thus produce borders when the paper is exposed to light.

Masking is a system of controlling negative density ranges or color saturation through the use of unsharp masks.

Masking frame is an adjustable frame used to hold printing paper in position under the enlarger, also referred to as an enlarging easel.

Mastic varnish is varnish used for negatives.

Mat is an alternative term used for matte. Also describes the cardboard surround in a picture frame.

Matte field is a granular textured surface that disperses light in order to form a clear image. Used in the viewfinder optical system.

Matrix is a relief image, usually made from gelatin and used for processes such as dye transfer printing.

Matte is a term used to describe a non reflective, non-textured surface.

Matte box is a mask used to make images suitable for wide-screen projection.

Meniscus lens is a simple lens consisting of a single piece off glass, thicker at the center than at the edges. It has one concave and one convex face.

Mercuric chloride is a chemical used in certain types of intensifiers.

Mercury vapor lamp is an artificial light source produced by passing current through mercury vapor in a tube.

Metal print is a photographic print made on a sensitized metal surface

Methyl alcohol is a volatile, poisonous spirit commonly known as wood alcohol. Used as a substitute for pure alcohol in some photographic processes.

Metol is a reducing agent which is soft working, especially in the presence of a weak alkali.

Metolquinone is a combination of metol and hydroquinone, used as a developing agent (MQ developer).

Microfiche is a sheet of microfilm usually forming part of a filing system.

Microfilm is a film used to produce a microscopic record of a document and intended for projection.

Microflash is an electronic flash of very short duration used to illuminate subjects traveling at a very high rate of speed.

Micro lens is a lens for microscopic photography. Not to be confused with a Macro lens.

Micron (µ) is one millionth of a meter.

Microphotograph is a photograph produced to a very small size which can be viewed with a microfilm reader.

Microprism collar is a grid type ring found in the center of a camera focusing screen, usually surrounding a split image screen.

Midtone is an area in a print or scene that contains average values.

Millimicron (mµ) is one thousandth part of a micron.

Miniature camera is a term commonly applied to cameras with a format size of less than 35mm.

Mired is an abbreviation for the term micro reciprocal degrees, a scale of measurement of color temperature. The mired value of a light source is calculated by dividing 1,000,000 by its color temperature in Kelvins.

Mirror box is a box containing one or more mirrors, usually angled to the light beam, as in the main body of an SLR camera.

Mirror lens is a lens system which uses mirrors within its internal construction. Most lenses of this type have a mixture of reflecting and refracting optics and are known as catadioptric lenses.

Microfiche is a sheet of microfilm usually forming part of a filing system.

Mode is the prime operating function of SLR cameras, e.g. manual mode, aperture priority mode, shutter priority mode, etc.

Modeling light is a light used to create a three dimensional effect achieved through the perception of form and depth.

Modelscope is a device employing a short rigid endoscope fitted with a right angle mirror at its tip, used to photograph scale models from a seemingly eye-level viewpoint

Modular enlarger is an enlarger with interchangeable filtration heads and illuminations systems.

Monobath is a single solution which combines developer and fixer for processing b&w negatives. It is a quick simple system but does not allow for development control.

Monochromatic are light rays of a single wavelength.

Monochrome is single colored. It is most frequently applied to black and white photographs, but can also describe sepia and other toned images.

Monopack is an outdated term describing a film carrying system.

Monorail camera is a sheet film camera, of modular construction, mounted on a rail system to give maximum camera movements.

Montage is a composite picture made from a number of photographs.

Mordant is a colorless dye absorbing substance used in some forms of toning. The silver image is converted into a mordant then soaked in dye.

Mosaic is a composite made up from a patchwork of partly overlapping photographs.

Motor drive is an automatic film wind-on mechanism which can be attached to some cameras. While the shutter remains depressed the film will keep winding on after exposure.

Mottle is a processing fault characterized by random print density differences.

Mount is a frame and/or backing used to support and protect prints and transparencies.

MQ/PQ developers are developing solutions containing the reducing agents metol and hydroquinone or phenidone and hydroquinone.

M-synch is a flash setting or socket which synchronizes the firing of the shutter with the peak light output of a flash bulb.

MTF (Modulation transfer function) A comparison of contrast between a test chart and the reproduced image. One of the measurements of lens performance used in the manufacturing process.

Multi-band photography is a method of aerial photography using cameras and scanners which are sensitive to different wavelengths in the spectrum to record different subject characteristics.

Multimode camera is a 35mm camera that will operate in several modes.

Multiple exposure is the technique of making more than one exposure on the same film frame, normally so that the images are superimposed.

Multiple flash is the use of more than one flash unit, usually operating simultaneously to light a subject.

Munsell system is a method of precise color description, based on comparison with comprehensive hue and saturation charts. Has closest application to pigments, whereas the CIE system relates directly to light.

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Photo Glossary - N

Nadar is the name adopted by the first aerial photographer, G. F. Tournachon, who took photographs from an air balloon.

Nanometer is a unit of measurement of light wavelength. A nanometer is one millionth of a millimeter.

Naphtha is a volatile petroleum based solvent such as benzine or gasoline (but not kerosene).

ND is an abbreviation for neutral density.

Near ultraviolet are wavelengths from about 400nm down to 250nm. Most photographic emulsions are sensitive to this range of bands.

Negative is the image produced on a photographic emulsion by the product of exposure and development, in which tones are reversed so that highlights appear dark and shadows appear light.

Negative carrier supports the negative between the light source and the enlarging lens of an enlarger.

Negative lens is a simple concave lens that causes rays of light to diverge away from the optical axis.

Negative/positive paper is paper used to print a positive color image from a negative.

Neo-coccine is a red dye used in retouching to stain the gelatin.

Neutral density is a technique which makes possible shorter printing times in color printing.

Neutral density filter describes a gray camera filter which has an equal opacity to all the colors of the spectrum and so does not affect the colors in the final image. It is used to reduce the amount of light entering the camera when aperture or shutter settings must remain constant.

Neutral filtration in color printing is the filtration at which color balance is achieved, rendering a neutral gray ion the film image as a neutral gray on the photographic paper.

Neutralizer is a chemical designed to counteract and make inactive another chemical solution.

New Objectivity is an approach to the subject matter of photography originating in Germany in the 1920s. The photographer remains an impartial observer, intensifying the appreciation of forms and structures in ordinary things but de-personalizing his/her approach.

New Realism is an alternative name for New Objectivity.

Newton's rings are rings of colored light produced when two glass or transparent surfaces are in partial contact.

Nitraphot is a tungsten filament lamp similar to the photoflood but with a longer working life.

Nitrate base was an early flexible film support which was highly inflammable.

Nitric acid is used in emulsion manufacture, in toners, and in bleaches, it is highly corrosive.

Nodal plane is an imaginary line passing through the nodal point, perpendicular to the optical axis.

Nodal points are located in two areas in a compound lens system. The front nodal point is where rays of light entering the lens appear to aim. The rear nodal point is where the rays of light appear to have come from, after passing through the lens. Nodal points are used to calculate optical measurements.

Non-silver processes are image making processes that do not require the use of metallic silver, such as Gum bichromate.

Non-substantive is a name given to color film in which the color couplers are not contained within the emulsion, but are introduced during processing.

Normal lens describes a lens with a focal length approximately equal to the diagonal of the film format for which it is being used.

Notch is a V or U shaped cut into one edge of sheet film. It denotes the location of the sensitive side of the film as well as identifying the type of film.

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Photo Glossary - O

Objective is the lens used closest to the specimen in microscopes or telescopes.

Off the film metering is a meter which determines exposure by reading light reflected from the film during exposure. Pioneered by Olympus on its OM2n. Most flash modes have OTF.

Oil reinforcement is a method of altering the tonal range of prints on matte or textured fiber papers. The dried print is rubbed with a medium consisting of two parts of turpentine to one of mastic varnish and one of linseed oil. Artists oil color is then applied locally to the print.

One shot color camera is an obsolete plate camera making three color separation negatives from a single exposure.

One shot developer is a developer that is used on a single occasion and then discarded.

Opacity is the light stopping power of a a material. The greater the opacity of a substance, the more light its stops. In photography, opacity is expressed as a ration of the amount of light falling on the surface of the material to the amount of light transmitted by it.

Opalescent is like opal, a material with a cloudy-white translucent appearance.

Opal lamp is a filament lamp with an opal glass bulb for optimum diffusion.

Opalotype is an obsolete printing process in which a carbon-process image is transferred on to translucent opal glass.

Opaque liquid is a dense red or black pigment, dissolved in water to form a liquid paint used to fill in film areas that are required to pint as pure white.

Open flash is a method of flash operation using the following sequence: shutter opened, flash fired, shutter closed. Usually shutter duration is unimportant since the available light is much dimmer than the flash.

Opening up is increasing the size of the lens aperture or decreasing the shutter speed to admit more light to the film.

Optical axis is an imaginary line passing horizontally through the center of a compound lens system.

Optical bench is a device for measuring the optical performance of lenses.

Optical glass is used for manufacturing lenses and prisms. It is specially manufactured to be free of defects and distortion, and to withstand heat and humidity. Each type f optical glass is classified according to its refractive index and light dispersive quality. Two or more types of optical glass are typically used in the component elements of photographic lenses.

Optical sensitizing is a method of increasing a films sensitivity by the use of dyes.

Optical wedge is a strip of material, clear at one end and gradually increasing in opacity, which is used to determine the effect of light intensities on sensitized materials.

Optics is the science dealing with the behavior of light.

Ordinary emulsion is a term applied to a photographic emulsion which is only sensitive to ultra-violet and blue light.

Orthochromatic is used to describe an emulsion which is sensitive to blue and green light, but insensitive to red.

Orth-phenylene diamene is a fine-grain developing agent.

Over-development is a term indicating that the amount of development recommended by the manufacturer has been exceeded. It can be caused by prolonged development time or an increase in development temperature, and usually results in an increase in density and contrast.

Over-exposure is an expression used to indicate that the light sensitive material has been excessively exposed.

Over-run lamp is a tungsten light source specifically used at a higher voltage than normal to increase light output and achieve constant color temperature.

Oxalic acid are soluble white crystals used in some toners.

Oxidation product is the chemical produced by a color developer during the conversion of exposed silver halides to black metallic silver.

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Photo Glossary - P

Painting with light - technique of lighting large, dark interior. The camera, mounted on a tripod, is given a long time exposure. The photographers moves continuously around the interior, giving flash or battery powered photoflood illumination to the shadow areas.

Pan and tilt head - tripod head allowing the camera to be tilted up and down or turned through a 360° arc.

Panchromatic - photographic emulsion sensitive to all the colors of the visible spectrum and to a certain amount of ultra-violet light. The sensitivity is not uniform throughout the spectrum.

Panchromatic vision filter - filter through which the subject can be viewed approximately as it would appear in monochrome as recorded by a panchromatic emulsion.

Panning - technique of photographing moving subjects. While the shutter is open, the camera is swung in the same direction as the subject is moving. This creates a blurred background, but a sharp subject.

Panorama - picture presenting a continuous view of the landscape, produced either by using a panoramic camera or from a composite of several images.

Panoramic camera - camera with a special type of scanning lens which rotates on its rear nodal point and produces an image of the scanned area on a curved plate or film.

Paper base - support for the emulsion used in printing papers.

Paper characteristic curve - describes a graphical relationship between exposure values and image density of a printing paper. Each brand of paper may have a different initial characteristic curve. The shape of the curve can be altered by different developers, development times, temperatures, and toning.

Paper grade - numerical and terminological description of paper contrast: numbers 0 - 1 soft; number 2 normal; number 3 hard; number 4 - 5 very hard; number 6 ultra hard. Similar grade number from different manufacturers do not have the same characteristics.

Paper safe - light-tight container for unexposed photographic papers, with an easy open positive closing lid.

Parabolic mirror - silvered glass or metal reflector with a parabolic axial cross-section, used to produce near parallel rays from a light source positioned at its geometrical focus.

Parallax - difference between the image seen by a viewing system and that recorded on film. Only TTL viewing systems avoid parallax error.

Paraphenylenediamine - reducing agent used in some fine grain and color developers.

Paraphotography - general term for non-silver-halide image forming processes.

Paraxial - rays nearest the optical axis of a lens.

Patch chart - squared pattern test strip often made when color printing by the additive method.

PCT - see Photo color transfer.

PEC - see Photo-electric cell.

Pellicle (pellicule) - thin film used in one-shot color cameras as a semi-reflecting surface.

Pentaprism - optical device, usually fitted on 35mm cameras, which makes it possible to view the image while focusing. A mirror device laterally reverses the image so that the scene is viewed through the camera upright and the right way round.

Percentage solution - solution containing a given quantity of a dissolved substance in a stated volume of solvent.

Perforations - accurately spaced holes punched throughout the length of film for still cameras. Basically the perforation function as a guide for precision registration of film and also provide mechanical movement from frame to frame.

Periphery photography - technique used to photograph the entire inner or outer surface of a cylinder or tube.

Permanence tests - methods of establishing whether long term permanence of an image has been achieved.

Perspective - relationship of size and shape of three-dimensional objects represented in two-dimensional space.

Petzval lens - early lens system developed by Joseph Petzval. It had a very wide aperture and was relatively free from aberration. Many modern lenses have developed from this simple three-element design.

Phenidone - reducing agent used in many fine grain solutions.

Phenol varnish - resin used to produce a hard durable top coating.

Phosphorescence - property held by some materials of absorbing light of one wavelength and emitting it as light of a different wavelength.

Phosphotophotography - technique of projecting an infrared image on a phosphorescent surface.

Photo color transfer - method of making color enlargements by exposing on full size sheet film which is then soaked in a activator solution and rolled in face contact with receiving paper. The sandwich is then left in normal light for 6-8 minutes and peeled apart to give a finished print.

Photo elasticity - method of determining stress patterns in structures with the aid of polarized light.

Photo-electric cell - light sensitive cell. Two types are used in exposure meters. A selenium cell generates electricity in proportion to the amount of light falling upon its surface. A cadmium sulfide cell offers a resistance to a small electric charge when light falls upon it. Cadmium sulfide cells are more sensitive then selenium, especially at low light levels.

Photo-engraving - production of a relief printing surface by chemical or mechanical means, with the aid of photography.

Photo-etching - technique of contact printing an image on lith film on a presensitized zinc plate which is then processed and chemically etched to give a relief image.

Photo file index print - makes ordering reprints and enlargements easy. A small print shows a positive, "thumbnail" version of every picture on an APS roll. Each thumbnail picture is numbered on the index print to match the frames inside the cassette.

Photoflood - artificial light source using a tungsten filament lamp and a dish reflector.

Photogenic drawing - original name given by William Fox Talbot to his earliest method of recording camera images.

Photogram - pattern or design produced by placing opaque or transparent objects on top of a sensitive emulsion, exposing it to light and then developing it.

Photogrammetry - method of making precise measurements from photographs.

Photography - literally writing or drawing with light (from the Greek words photos meaning light and graphos, writing). First suggested by Sir John Herschel to William Fox Talbot in 1839.

Photogravure - method of printing photographs from an etched copper plate.

Photolamp - tungsten filament photographic lamp with a large diffused bulb, giving light of 3200 K (kelvin).

Photolinen - laminate of linen and paper coated with black and white photographic emulsion. It is used for photographic wall coverings.

Photolithography - lithographic printing process using an image formed by photographic means.

Photometer - instrument for measuring light being reflected from a surface. It works by comparing the reflected light with a standard source produced within the photometer.

Photomicrography - system of producing larger than life photographs by attaching a camera to a microscope.

Photon - particle of light energy. It is the smallest quantity of radiant energy that can be transmitted between two systems.

Photo-reportage - use of photographs in newspapers and magazines, to supplement or replace written journalistic accounts.

Photo-resistor - photoelectric cell which varies in its electrical resistance according to the light received.

Photo-silkscreening - method of silkscreening images, using a stencil produced photographically.

Photo telegraphy - transmission of pictures between two points by means of radio or telegraph. A print is wrapped around a cylinder and scanned by a small spot of light. Reflected light values are transmitted as a stream of signals. They control an exposing light source at the receiving station, which exposes light sensitive material on a similar drum.

Photo-transistor - light sensitive electronic component which functions as a switch. Used for slave firing of electronic flash heads.

pH scale - numerical system running from 0-14 and used to express the alkalinity or acidity of a chemical solution. 7 is neutral. Solutions with a lower pH value are increasingly acidic, and those with a higher pH value are increasingly alkaline

Physical development - system of development in which silver is contained in suspension within the developer and is attracted to the emulsion by silver halides which have received exposure.

Physiogram - photographic patter produced by moving a regulated point of light over a sensitive emulsion.

Pictorialist - photographs which are a picturesque, decorative art in their own right and appeal to the viewers sense of beauty.

Piezo-electric flash - tiny flash bulbs (normally housed in flash cubes) which can be fired by a very low current produced by striking a piezo-electric crystal. Such bulbs can therefore be used without a battery.

Pigment - coloring material that is insoluble in the liquid carrier with which it is mixed. Examples include paint or poster color.

Pigment processes - making a positive print by using the property of bichromated colloids by changing their physical characteristics with exposed light. Gum bichromate is a pigmented process.

Pinacryptol - yellow and green dye powders which are used in desensitizing solutions.

Pincushion distortion - lens aberration causing parallel, straight lines at the edge of the image to curve toward the lens axis.

Pinhole camera - camera without a lens which uses a very small hole pierced in one end to allow light to pass through and form an image on the back of the camera which can be covered by film.

Pixels - abbreviation for picture elements. The tiny squares of light making up the picture are transmitted in digital form and reconstituted as a visual image.

Plane - imaginary straight line on which image points may lie or which passes at right angles through a set of points perpendicular to the optical axis.

Plates - early photographic glass plates coated with emulsion.

Plate camera - camera designed to take glass plates but often adapted to take cut film.

Platinotype - obsolete contact printing process popular among pictorialists.

Point source lamp - arc type lamp producing light from a small gap between two carbon rods.

Polarization - light said to travel in a a wave motion along a straight path, vibrating in all directions. Polarization can be brought about with a polarizing filter which causes light to vibrate in a single plane only. Polarizing filters are used over camera lenses and light sources to reduce or remove specular reflection from the surface of objects.

Polarized light - rays of light that have been restricted to vibrate in one plane only.

Polarizing filter - colorless gray filter made from stressed glass. Polarizing filters are used over light sources or camera lenses to reduce or remove specular reflection from certain types of surfaces.

Polaroid camera - an instant picture camera designed for Polaroid materials.

Pola-screen - another term for a polarizing filter.

Portrait lens - lenses produced specifically for portraiture. They usually have a long focal length and produce a slightly diffused image.

Positive - in photography, the production of prints or transparencies in which light and dark correspond to the tonal range of the original subject.

Positive lens - simple lens that causes light rays from a subject to converge to a point.

Positive/positive printing - process for printing a color transparency directly on paper to produce a positive print.

Posterization - photographic technique using a number of tone separated negatives which are printed on high contrast material. A master negative is made by printing these in register. The final print from this contains selected areas of flat tone in place of continuous tone. Sometimes incorrectly referred to as solarization.

Potassium bichromate - chemical used in chrome intensifiers.

Potassium bromide - chemical used as a restrainer in most developing solutions and as a rehalogenizing agent in bleaches.

Potassium carbonate - highly soluble alkaline accelerator used in most general purpose and print developing solutions.

Potassium chloride - chemical used in some bleaches and sensitizers.

Potassium citrate - chemical used in blue and green toners.

Potassium dichromate - See Potassium bichromate.

Potassium ferricyanide - chemical used in Farmer's reducer as a bleach.

Potassium hydroxide - caustic potash. Highly active alkali, used as the basis for high contrast developing solutions.

Potassium iodide - chemical used in bleaches, toners and intensifiers.

Potassium metabisulfite - acidifier used in fixers and stop baths.

Potassium permanganate - chemical used extensively in reducers, bleaches and toners.

Potassium persulfate - chemical sometimes used in super-proportional reducers.

Potassium sulfide - chemical used in sulfide toning.

Potassium thiocyanate - chemical used in some fine grain developers as a silver solvent.

Prehardener - chemical solution used to harden the gelatin of an emulsion prior to processing.

Preservative - chemical, commonly sodium sulfite, used in developing solutions to prevent rapid oxidation of the reducing agents in use.

Preset focus shooting - technique in which focus is set at a predetermined setting and the shutter is released when the subject moves into the focus point.

Pre-soak - preparatory water bath for film or paper prior to processing that prevents uneven development. It is essential in some color processes.

Press focus lever - lever found on the between-lens shutter of many large format cameras. It allows the shutter blades to be held open for lens focusing no matter what shutter speed has been set.

Primary colors - three primary additive colors of the spectrum in terms of transmitted light. These colors are blue, green and red.

Principal axis - imaginary line which passes through the center of curvature of all the lens elements.

Principal planes - imaginary lines which pass through the nodal planes of a lens system.

Principal point - point from which the focal length is measured. The principal point of a simple lens is located at the center of the lens. Compound lenses have two principal points, the location of which cannot be determined by appearance.

Print - in photography is an image, normally positive, which has been produced by the action of light on paper or similar material coated with a light sensitive emulsion.

Printing - process employed to make one or a number of images on paper or similar material.

Printing-in - system of local shading control used in printing in which additional exposure is given to selected areas of a print.

Printing-out papers - light sensitive printing papers which visibly darken during exposure to sunlight. Also referred to as contact printing papers.

Prism - transparent medium capable of bending light to varying degrees, depending on wavelength.

Processing - sequence of steps whereby a latent photographic image is converted into a visible, permanent image.

Process lens - lens system designed specifically for high quality copying.

Projection cutting - any method of printing in which the image is optically projected on the sensitized material.

Projector - apparatus used to display enlarged still or moving images on to a screen.

Proportional reducer - chemical method of reducing excess density and contrast from a photographic negative.

Protective toning - toning process used to protect black and white prints from fading and give archival permanence. Usually used selenium or gold toners.

Pulling - method of underrating the normal ISO speed of a film to produce an overexposed latent image.

Pushing - method of overrating the normal ISO speed of a film to produce an underexposed latent image. Used to increase the working speed of a film.

Push processing - increasing the development time of a film to increase its effective speed. See Pushing.

Pyro - reducing agent sometimes used in developing solutions.

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Photo Glossary - Q

Quantum - smallest indivisible unit of radiant energy.

Quarterplate - negative or print format measuring 3 ¼ x 4 ¼ inches. It's one quarter the size of a full plate (8 ½ x 6 ½ inches).

Quartz-iodine lamp - compact tungsten filament lamp designed to maintain its color temperature and light intensity throughout its working life.

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Photo Glossary - R

Rack and pinion focusing - mechanical focusing system used on copying or monorail cameras. A pinion engages a rack on a slide. Focusing is achieved by turning a knob or wheel, which moves the lens or image panel.

Radiography - technique of using X-rays, gamma rays and charged particles to form shadow images on photographic materials. Used in medical and industrial research because of its ability to penetrate opaque objects.

Rangefinder - focusing system which measures the distance from camera to subject.

Rapid fixer - fixing solution that uses ammonium thiocyanate or thiosulfate instead of hypo.

Rapid rectilinear - lens system composed of two matching doublet lenses, symmetrically placed around the focal aperture. It was introduced by Dallmeyer and Sternheil and removed many of the aberrations present in more simple constructions.

Rayographs - term coined by Man Ray and his friends for pictures made by placing directly on photographic paper (i.e. photograms).

Rear curtain sync - when the flash fires an instant before the second or rear curtain of the focal plane shutter begins to move. When slow shutter speeds are used, this feature can create a blur effect from the ambient light, i.e., patterns following a moving subject with subject movement frozen at the end.

Rear focus - refers to the focused area behind the picture's subject.

Rear focusing system - system where only the rear lens group moves during focusing. It eliminates changes in the physical length of the lens during focusing.

Rebate - margin on photographic film surrounding the image area.

Reciprocity failure - in photographic emulsions occurs when exposure times fall outside a films normal range. At these times an increase in exposure is required in addition to the assessed amount. This can be achieved either by increasing intensity or time.

Reciprocity law - states that exposure = intensity x time, where intensity is equal to the amount of light and time is equal to the time that amount of light is allowed to act upon the photographic emulsion.

Reconstituted image - photograph produced by translating light from the subject into electronic signals.

Recycling time - time it takes a flash unit to recharge between firings.

Red eye - effect encountered when light from a flash unit travels parallel to the lens axis during exposure.

Reducers - solutions which remove silver from negatives and prints. They are used to diminish density and alter contrast on a photographic emulsion.

Reducing agent - chemical in a developing solution which converts exposed silver halides to black metallic silver.

Reflected light - light bounced off a subject, not falling on it.

Reflected light reading - measurement by a light meter of the amount of reflected light being bounced of the subject. The light meter is pointed towards the subject.

Reflecting telescope - telescope using a concave parabolic mirror to increase focal length and focus light at a point.

Reflections - rays of light which strike a surface and bounce back again. Specular reflection occurs on even, polished surfaces; diffuse reflection occurs on uneven surfaces, when light scatters.

Reflector - any substance from which light can be reflected. It also describes a white or gray card used to reflect from a main light source into shadow areas.

Reflex camera - camera system which uses a mirror to reflect incoming image rays on to a ground glass screen, providing a system of viewing and focusing. See also SLR.

Reflex lens - alternative term for mirror lens.

Refraction - change in direction of light rays as they pass obliquely from one transparent medium to another of different density, e.g. air to glass.

Refractive index - numerical value indicating the light bending power of a medium such as glass. The greater the bending power, the greater the refractive index.

Register - exact alignment when overlaying separate images.

Register punch - punched used to make alignment holes in film or paper for registering images.

Rehalogenization - process by which black metallic silver is converted back to silver halides. It is used in bleaching for toners and intensification.

Relative aperture - measurable diameter of the diaphragm divided by the focal length of the lens in use and expressed in terms of "f" numbers, marked on the lens barrel.

Replenishment - addition of chemicals to a processing solution to maintain its characteristics, e.g. developers are replenished with reducing agents as the old ones are exhausted through use.

Resin coated paper (RC) - printing paper with a water repellent base. RC Paper can be processed faster, require less washing, and dry more quickly than fiber based papers.

Resist - protective but removable layer applied to a surface in the form of a pattern or image. Used to prevent chemicals solutions reaching covered areas.

Resolving power - ability of the eye, lens or photographic emulsion to determine fine detail. In photography, the quality of the final image is a result of the resolving power of both the lens and the sensitive emulsion. Resolution is expressed in terms of lines per millimeter which are distinctly recorded or visually separable in the final image.

Restrainer - chemical constituent of developing solutions which helps prevent reducing agents from affecting unexposed halides and converting them to black metallic silver.

Reticulation - regular crazed pattern created on the emulsion surface of negatives which is caused by extreme changes of temperature or acidity/alkalinity during processing.

Retrofocus - type of lens design with a negative lens element positioned in front of the diaphragm and a positive lens element positioned at the rear of the diaphragm. This makes the distance from the rear of the lens to the focal plane longer than the lens focal length. Retrofocus design has been adopted in wide angle lenses so the rear of the lens does not impede the movement of an SLR camera's reflex mirror.

Retouching - after treatment carried out on a negative or print, in the form of local chemical reduction, local dye or pencil additions or air-brushing. The purpose is to remove blemishes on the negative or print.

Reversal materials - materials specifically designed to be processed to a positive after one camera exposure.

Ring flash - ring shaped electronic flash unit attached to the front of a lens. Used to give even frontal lighting in closeup situations.

Rinse - brief clean water wash between steps of a processing cycle to reduce carry-over of one solution into another.

Rising front - camera movement enabling the front lens panel to be raised or lowered from its central position on most view cameras.

Rods - receptors forming part of the retina at the back of the eye sensitive only to variations in brightness, not color.

Roll film - refers to 120, 220 and 620 film formats.

Roll film adaptor - specially designed attachment for cameras designed for cut film, enabling roll film to be used.

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Photo Glossary - S

Sabattier effect - part positive part negative effect formed when an emulsion is briefly re-exposed to white light during development, and then allowed to continue development. Also known as pseudo-solarization.

Safelight - darkroom light of a color and intensity that will not affect light sensitized photographic materials.

Safety film - term used to describe a film with a base that is not readily inflammable.

Sal-ammoniac - ammonium chloride. used in some high speed developers.

Sandwiching - combination of two or more negatives or film positives in the negative carrier or masking frame when printing or enlarging.

Saturated color - pure color hue, undiluted by other colors, white or gray, i.e. the primary colors, red, yellow and blue are saturated colors.

Scale - linear relation between the size of the subject and the size of its image.

Scanning electron microscope - device used in photomicrography.

Schumann plate - plate coated with an emulsion with so little gelatin content that the silver halide grains protrude above its surface. Used for photography in the ultraviolet region.

Screening - conversion of a continuous tone image to a half-tone image.

Screen plate - plate used in early additive forms of color photography.

Scrim - lighting attachment which, when placed in front of a lamp, reduces its strength, usually by one stop, without affecting lighting quality or color.

Selective focusing - method of adjusting the lens aperture and shutter speed to give a depth of field that will limit image sharpness to a particular area of the image.

Selenium - light-sensitive substance which, when used in a barrier-layer construction, generates electrical current when exposed to light. Used in exposure meters.

Selenium cell - light sensitive cell used in many types of exposure meters. It generates electricity in direct proportion to the amount of light falling upon its surface.

Self-timer - mechanism for delaying the opening of the shutter for a given number of seconds after the release has been operated.

Self toning paper - obsolete silver chloride paper used for contact printing in daylight.

Sensitive material - in photography, refers to materials that react to the actinic power of light.

Sensitivity - degree of response of a photographic emulsion to exposure to light.

Sensitometry - scientific study of the response of photographic materials to exposure and development. It establishes emulsion speeds and recommended development and processing times.

Separation images - technique of producing an image by combining photographs produced on a material or using equipment which is sensitive to one region of the visible spectrum.

Separation negatives - black & white negatives, usually prepared in lots of three or four, which have been taken through filters which analyze the color composition of an original in terms of blue, green and red. They are used particularly in photomechanical color printing and dye transfer printing processes.

Shading - see Local control.

Shadow detail - details visible in areas that are darkest in the subject.

Shadows - darkest areas in a photographic print.

Sheet film - alternative term for cut film.

Shelf life - length of time unused material or chemicals will remain fresh.

Shellac - natural resin with a low melting point. It is mainly used on dry mounting tissue.

Shutter - mechanical system used to control the time that light is allowed to act on the sensitive emulsion.

Shutter priority camera - semi-automatic camera on which the photographer selects the shutter speed, and the camera automatically sets an appropriate aperture.

Shutter speed - action of the shutter that controls the duration of an exposure. The faster the speed the shorter the exposure. Shutter speed settings are given in the fraction of a second. Each setting is half the duration of the preceding one in a constant scale, marked on the shutter speed dial or ring.

Side lighting - light striking the subject from the side relative to the position of the camera. It produces shadows and highlights to create modeling on the subject.

Silhouette - photographic image in which the subject is seen as a solid black shape against a light background.

Silicon release paper - thin, heat resistant interleaving paper, used between a photographic print and textured material in a heated press. It allows remolding of the print surface yet prevents the two materials from sticking together.

Silk print - image made on silk by means of the diazo or dye printing methods.

Silkscreen - method of applying inks to paper or similar materials using a nylon stencil produced by photographic means.

Silver dye bleach material - integral tripack printing material.

Silver halides - light sensitive crystals used in photographic emulsions, i.e. silver bromide, silver chloride and silver iodide. The change from white to black metallic silver when exposed to light.

Silver nitrate - chemical combination of silver and nitric acid. It is used in intensifiers, physical developers and photographic emulsions manufacture.

Silver reclamation - system for recovering silver from exhausted solutions.

Silver recovery - system of reclaiming silver from exhausted solutions.

Silver salts - compounds of silver.

Simultaneous contrast - effect that adjacent color hues have upon each other.

Single lens reflex (SLR) - stands for single lens reflex. It is a camera of 35mm or medium format in which a system of mirrors shows the user the image precisely as the lens renders it.

Single servo AF - when focus is locked as long as the shutter release button is lightly pressed.

Sizing - very dilute, gluey substance used to prepare surfaces for coating by filling in pores and giving even absorbance.

Sky filter - outdated term for a filter which has a graduated density across its surface.

Sky shade - alternative term for a lens hood.

Slave unit - mechanism which fires other flash sources simultaneously when a photo-electric cell is activated by the illumination emitted by a camera linked flash.

Slide - alternative term for a projection transparency.

Slit shutter - narrow vertical slit either just in front of the emulsion or at a similar distance in front of the lens. Film is wound through the camera at a constant speed giving one long image along the length of the film.

Slow film - film having an emulsion with low sensitivity to light. Typically films having an ISO or 50 or less.

Slow lens -lens with a small maximum aperture, such as f/8.

Slow sync - flash technique for using the flash at a slow shutter speed. Flash shooting in dim light or at night at a fast shutter speed often results in a flash-illuminated subject against a dark background. Using a slower shutter speed with the flash brings out the background details in the picture.

Slide - photographic transparency mounted for projection. It represents first generation production of an image.

Snapshot - term once used to describe a photograph taken with the I (instantaneous) setting on cameras. The term originally came from rifle shooting, when little or no time is allowed for aiming.

Snoot - cone shaped shield used on spotlights to direct a cone of light over a small area.

Sodium bichromate - chemical used in intensifiers, toners and bleaches.

Sodium bisulfite - chemical used in fixing baths as an acidifying agent.

Sodium carbonate - alkaline accelerator used in many general purpose and print developers.

Sodium chloride - used in some bleaches and reducers.

Sodium hexametaphosphate - water softener.

Sodium hydrosulfite - used as a fogging agent in reversal processing.

Sodium hydroxide - highly active alkaline accelerator used in conjunction with hydroquinone to produce high contrast developers.

Sodium metabisulfite - used as an acidifying agent in acid fixing baths.

Sodium sulfide - chemical used in sulfide (sepia) toning.

Sodium sulfite - chemical commonly used as a preservative in many developing solutions.

Sodium thiocyanate - alternative to potassium thiocyanate and is used as a silver solvent in physical and ultra-fine grain formulae.

Sodium thiosulfate - chemical used in many fixing solutions. It converts unused halides to a soluble complex which can be removed by washing.

Soft developer - paper developer that can be used alone or in combination with other developers (two-bath development) to achieve more subtle contrast control.

Soft focus - definition of a diffused image. This can be achieved at the camera or enlarging stage.

Soft focus lens - lens, uncorrected for spherical aberrations, used to produce a soft focus effect.

Solarization - reversal or partial reversal of tones in a photographic image caused by vast amounts of over-exposure. It is often inaccurately used to describe the partial reversal effect caused by fogging photographic material with light, which is actually the Sabattier effect.

Solubility - in general terms is the ease with which a solid will mix homogeneously with water to provide a chemical solution.

Spacing bracket - device used to position the camera at the right distance from the subject for the lens focus setting in closeup work.

Spectral sensitivity - relative response of a photographic emulsion to each of the colors of the spectrum, including infrared and ultraviolet.

Spectrum - usually used in reference to the visible part of the electro-magnetic spectrum, i.e. the color bands produced by diffraction, and arranged according to wavelength, when white light is passed through a prism.

Speed - sensitivity of a photographic emulsion to light. Films are given ISO or DIN numbers denoting speed characteristics.

Spherical aberration - lens fault which causes loss of image definition at the image plane. Its affects are reduced by stopping down.

Split image rangefinder - see Rangefinder.

Spool - bobbin like object consisting of a narrow core with flat disks on either end, around which the film is wound.

Spotlight - artificial light source using a fresnel lens, reflector, and simple focusing system to produce a strong beam of light of controllable width.

Spot meter - used to get accurate light readings of a small part of a subject. It uses a narrow angle of view to measure within limited areas.

Spotting - method of retouching. Blemishes or unwanted details are removed from negatives and prints by brush and dye or pencil.

Sprocket holes - perforations on both edges of 35mm film, which engage with the teeth of the film transport mechanism.

Squeegee - tool with rubber blades or rollers, used to squeeze water out of wet prints.

Stabilization - alternative method of fixing. Unused halides are converted to near stable compounds, insensitive to light. No washing is required.

Stabilizer - final solution often used in color processing which leaves the dyes produced by chemical development more stable and fade resistant.

Staining developer - developer, such as pyro, in which the oxidation products give extra image density by staining the gelatin.

Stand - alternative name for a tripod.

Standard lens - lens with a focal length approximately equal to the diagonal of the film format with which it is used.

Stand camera - large format camera usually mounted on a rigid stand.

Static marks - jagged fog marks on negatives as a result of a very dry film being rewound or unwound too rapidly.

Step wedge - printed series of density increases, in regular steps from transparent to opaque. Its a method of making exposure tests when enlarging.

Stereoscope - viewer which accepts pairs of stereoscopic images.

Stereoscopic camera - camera designed to take simultaneous images of the same subject from viewpoints separated by the same distance as that between the eyes.

Stereoscopy - method of creating a three dimensional effect on a two dimensional surface using a pair of images taken from slightly different viewpoints, and viewed through specially made stereo viewers.

Still life - inanimate subject, either in the studio, or outdoors, normally arranged to make full use of form, shape and lighting.

Stock solution - processing chemicals which may be stored in a concentrated state and diluted just before use.

Stop - aperture of a camera or enlarging lens.

Stop bath - chemical bath whose purpose is to stop development by neutralizing unwanted developer. This increases precision of development and prevents carry over of one chemical into another during development.

Stopping down - reducing the size of the lens aperture and thus the amount of light passing into the camera. It increases depth of field.

Stop down metering - TTL metering in which the light is measured at the picture-taking aperture.

Straight photography - term used to describe picture making with minimal manipulation of the photographic process.

Stress marks - black lines on a photographic emulsion caused by friction or pressure.

Strobe light - low power electronic flash that can fire repeatedly at regular, controlled intervals.

Studio camera - term given to a large format 12 x 15 inch camera on a wheeled stand.

Subbing - layer applied to a photographic support as a foundation for the emulsion.

Subject - person or thing photographed.

Subjective photography - interpretive image of the subject, with results influenced by the attitude of the photographer.

Sub-miniature camera - camera using a film format smaller than 35mm.

Substantive film - color film in which the color couplers are contained within the emulsion.

Subtractive primaries - yellow, magenta and cyan.

Subtractive synthesis - combination color system used in modern photography materials. The complimentary colors of yellow, magenta and cyan are formed to provide a reasonably full color image.

Successive color contrast - trick of the human eye by which the impression of a color is influenced by an immediately preceding color stimulus.

Sulfide toning - conversion of a black metallic silver image into a brown dye image. Usually known as sepia toning.

Sulfuric acid - high corrosive chemical used in reducers.

Supper coat - top coating of non-sensitized gelatin added to sensitized emulsions to form a protective layer.

Supplementary lenses - additional lens elements used with the standard camera lens to provide a new focal length.

Surface development - development process in which the image forms primarily on the surface of the emulsion and then penetrates deeper.

Surge marks - streaks on the image from each of the sprockets holes of 35mm film caused by excessive agitation.

Surrealism - originally an early 1920s artistic movement, now taken to indicate the production of unreal images which defy reason.

Swing back/front - term used to describe the movable lens and back panels of most view and monorail cameras. They allow manipulation of perspective and depth of field.

Symmetry - effect of an evenly balanced arrangement of visual information, such as pattern, on either side of a central division.

Synchronized flash - method of synchronizing flash light duration with the maximum shutter opening.

Synchro-sunlight - system of combining daylight and flash to achieve a controlled lighting ratio.

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Photo Glossary - T

T (Time) - shutter speed setting used for timed exposures longer than the numbered settings. The shutter opens when the release is pressed and closes when it is pressed again. Now largely super ceded by B (Bulb).

Tacking iron - heated tool used to stick part of the dry-mounting tissue to a print and its mounting board.

Tanks - containers for holding chemical solutions for processing films and plates.

Tanning development - type of developer used for processes that require a relief image, such as dye transfer.

Technical camera - see View Camera.

Teleconverter - optical system mounted between a camera body and the lens to increase the effective focal length of the lens.

Telephoto lens - compact lens construction which provides a long focal length with a short back focus.

Tempering bath - large tank or deep tray filled with water maintained at the correct temperature for processing. Used to house tanks, drums or trays as well as containers of processing solutions.

Tessar lens - famous German non-symmetrical lens design by Zeiss. It is based on the triplet lens.

Test strip - trial and error method of calculating exposure in photographic printing. A number of exposures are given to a strip of emulsion, over important areas of the image to help judge the correct exposure in the final print.

Texture - broadly defined as the surface character of an object.

Texture screen - transparent film or glass printed with a fine background pattern. They're interposed between the image and the paper to break up large areas of tone or for special effects.

T-Grain technology - name for Kodaks film emulsion technology used in all Kodak APS films. Uniquely shaped grains that align better than conventional silver crystals absorb and transmitting light more effectively to produce sharper images.

Thermography - recording images by means of the heat radiated from the subject.

"Thick" negative - antique term used to describe a dense negative.

"Thin" negative - antique term used to describe a negative lacking in density.

Through-the-lens - see TTL.

Thyristor flash gun - automatic flash gun which cuts off the flash when the exposure is correct. This conserves power, makes recycling quicker, and battery life longer.

Time and temperature - controlling factors of a chemical photographic process.

Time exposure - general term for an exposure longer than can be set using the camera's fixed shutter speeds.

Time gamma curve - see Gamma.

Time lapse photography - method of recording chemical and physical changes in a subject over a period of time by photographing it at regular intervals from the same viewpoint.

Timer - clock used to control processing.

Tinting - application of color tints, usually in the form of dyes or paints, to a photographic image to create or enhance color.

Tin-type - see Ferrotype.

Tomography - radiographic technique used in medial photography.

Tone - refers to the strength of grays between white and black. It relates to the brightness, lightness and darkness of the subject and is determined by illumination.

Tone line process - technique used to reproduce a photographic image so that it resembles a pen and ink drawing.

Toners - used to change the color of the photographic print by chemical baths. Through the system of bleaching and toning, the black metallic silver image is converted to a dye image.

Tone separation - process of reducing the tonal range of a photograph to a very restricted range. The final result has strong highlights and deep shadows with a set number of intermediate tones. Also refereed to as Posterization.

Tone values - various shades of gray between the extremes of black & white in a photographic image.

Toning - method of soaking the print in selenium or similar chemical(s) to help give the print an overall feeling of "richness".

Transfer processes - methods of transferring a photographic image from one surface to another.

Transmission - passage of light through a transparent or translucent material.

Transmitted light - light which is passed through a transparent or translucent medium. The amount of light transmitted depends on the density of the medium through which it is passed and on the brightness of incident light source. Transmitted light is always less than incident light, but the amount of loss depends on the density of the medium.

Transparency - positive image in black and white or color, which is produced on transparent film.

Transparent magnetic layer - information storage layer built into Advanced Photo System film that enables enhanced information exchange capabilities.

Transposing frame - frame used for printing pairs of stereoscopic negatives from a two lens camera.

Tray development - any process carried out in open trays rather than using tanks or similar apparatus.

Trichrome Carbro Process - method of making assembly color prints from separation negatives, using an adaption of the carbro process.

Tri-color filters - filters in deep primarily colors used to expose color prints by the additive method.

Trigger - term used to describe a shutter release.

Tripack - photographic material, used in color photography, consisting of three emulsion layers of different sensitivity each on its own base. It is used to obtain three separation negatives with a single exposure.

Triple extension - camera system in which lens-image distance can be extended by as much as three times its focal length. It is particularly useful for close-up photography.

Triplet lens - lens consisting basically of three elements, a diverging lens sandwiched between two converging lenses.

Tripod - three legged camera support. The legs usually feature sections that permit height adjustments.

T setting - see T (Time).

T stops - more accurate measurement of light entering a lens than "f" numbers. Whereas "f" numbers represent the ratio between measured diameter and focal length, "t" stops are based on actual light transmission at different diameters.

TTL - abbreviation for "through-the-lens" as referring to a metering system in which a suitable light sensitive mechanism within the camera body measures exposure from the image light passing through the lens.

Tungsten filament - artificial light source using a tungsten filament contained within a glass envelope.

Tungsten halogen lamp - improved version of the normal tungsten lamp. It is much smaller and more consistent in color temperature as the glass envelope used is non-blackening.

Tungsten light - light from standard room lamps and ceiling fixtures, not fluorescent.

Tungsten light film - See Type B Film.

Twin lens reflex (TLR) - camera having two lenses of the same focal length. One is used for viewing and focusing, the other for exposing the film.

Two-bath development - development of negatives in two stages. Developer without alkali is followed by an alkali bath, which activates development.

Two-color photography - simple method of color photography which analyzes the spectrum into two parts instead of three, forming images which are combined with complementary colors.

Type A film - color film balanced to artificial light sources at a color temperature of 3400K.

Type B film - color film balanced to artificial light sources at a color temperature of 3200K.

Type D film - obsolete term for film balanced for daylight.

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Photo Glossary - U

Ultrasonic image recording - image formation by measurement of ultrasound echoes translated electronically into a scanned visual image on a TV display. Also known as sonography.

Ultraviolet (UV) - part of the electromagnetic spectrum from about 400nm down to 1nm. It is invisible to the human eye, but most photographic materials are sensitive to near UV bands down to 250nm. It records as increased haze, particularly in distant views and at high altitudes, and may give a blue cast in color images. technique of projecting an infrared image on a phosphorescent surface.

Under-development - reduction in the degree of development. It is usually caused by shortened development time or a decrease in the temperature of the solution. It results in a loss of density and a reduction in image contrast.

Underexposure - result of too little exposure in the camera or at the enlargement stage.

Universal developer - name given to a number of developing solutions, usually MQ, indicating that they can be used for processing films and papers.

Uprating - no longer used term to define the process of increasing the manufacturers film speed by the use of: hypersensitizing; using specially prepared proprietary developers; or by a two stage process.

Uranium Nitrate - chemical used in toners and developers.

UV filter - filter which is used to absorb ultraviolet (UV) radiation.

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Photo Glossary - V

Vacuum back is a camera back with a perforated plate through which air is drawn by a pump. A sheet of film is therefore sucked flat against the plate and held firmly during exposure. Used for special large format cameras such as copying devices where dimensional accuracy is critical.

Vacuum easel is a compact printing frame which ensures firm contact between the film and paper by excluding air between the surfaces. Some types are used to hold the paper flat on the enlarger baseboard when enlarging.

Vanishing point is the point at which parallel lines, viewed obliquely, appear to converge in the distance.

Vapor discharge lamp is a lamp in which electrical current passes through a vapor or gas rather than through a wire filament, thus producing illumination.

Variable contrast paper is a printing paper in which the contrast can be varied depending on the color of the printing light. This can be altered by using different color filters.

Variable focus lens is a lens whose focal length can be continually varied within a given range. Also known as a zoom lens.

Veil is a uniformly distributed silver deposit in a photographic image, not forming part of the image itself. Also known as fog.

Video still camera is a camera using an electronic charge coupled device instead of film.

View camera is a large format camera which has a ground glass screen at the image plane for viewing and focusing.

Viewfinder is a system used for composing and sometimes focusing the subject. There are several types: direct vision, optical, ground glass or reflex.

Viewpoint is the position of the camera in relation to the subject.

Vignetting is a printing technique where the edges of the picture are gradually faded out to black or white. It also refers to a fall off in illumination at the edge of an image, such as may be caused by a lens hood or similar attachment partially blocking the field of view of the lens.

Vinyl film is an emulsion coating on a polyvinyl chloride acetate base, with less shrinkage than conventional film bases.

Viscose sponge is a synthetic sponge used to wipe surplus water off films before they are hung up to dry.

Viscous processing is a process using chemicals carried in sticky semifluid substances instead of normal liquids. Used for instant picture processing.

Volt is a unit of electrical potential difference and electromotive force.

Voltage stabilizer is a transformer used to produce a steady output voltage despite fluctuations of input voltage.

Vortograph is an abstract photograph made with a simple kaleidoscopic apparatus, first used by Alvin Langdon Coburn in 1917.

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Photo Glossary - W

Warm colors are any colors which, by association, suggest warmth, such as red, orange and yellow.

Warm tone developer is a developer producing image colors in chlorobromide papers ranging from warm black to reddish brown, according to type.

Washing is the final part of the processing cycle, which removes residual chemicals and soluble silver complexes from the emulsion.

Water bath are large water filled containers used to maintain processing trays, tanks or chemicals at the correct temperature.

Waterproof paper is another term for Resin-coated paper.

Water softeners are used to eliminate most of the minerals and slats found in hard water.

Watkins factor is an old system of development control, based on observation of the processing image under safe lights.

Watt is a unit of power in electricity.

Watt-second is an alternative unit of energy, equal to the joule.

Wavelength describes the distance from wave-crest to wave-crest between two corresponding waves of light in the electro-magnetic spectrum. Wavelengths are measured in nanometers (nm) and Angstrom units (A).

Waxed paper process is an early form of photography. A variation on the calotype process.

Weak is a negative or print which is low in contrast or density.

Wedge spectrogram is an indication of the spectral sensitivity of a sensitized material by exposing it to a spectrum of light through a graduated gray wedge.

Wet collodion is a much improved calotype developed by Frederick Scott Archer. A sensitized glass plate was dipped into a bath of silver nitrate and exposed while still wet. The improved speed made much shorter exposures possible.

Wet processing is processing by the application of chemicals in fluid form. The traditional method of photographic processing.

Wetting agents are chemicals which, when used in minute quantities, reduce the surface tension of water. They are usually added to the final wash of films and plates to improve draining.

White Light see White Light Spectrum.

White light control is the level or switch on a color enlarger which removes all color filtration and returns it when required.

White light spectrum is the electromagnetic wavelengths between 400-700 nanometers. Also referred to as the visible spectrum.

Whole plate is a negative or print format measuring 6 ½ x 8 ½ inches.

Wide-angle lens is a lens with wide covering power. It has a focal length which is less than the diagonal of the film format with which it is being used.

Wide-angle rack is an additional focusing rack used on large format cameras.

Wide area AF means the autofocus detection area is wider than normal. Making it easier to photograph moving subjects.

Wood print is a print made on a wood surface which has been photochemically prepared.

Working aperture is the widest aperture at which an acceptable image can be achieved.

Working solution is a liquid chemical that has been mixed and diluted for use.

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Photo Glossary - X

Xenon is a rare gas sometimes used with electronic flash tubes and enclosed arc light sources.

Xerography is a photographic process which uses an electrically charged metal plate. On exposure to light the electrical charge is destroyed, leaving a latent image in which shadows are represented by charged areas. A powdered pigment dusted over the plate is attracted to the charged areas, producing a visible image.

Xography is a system of photography which produces prints and transparencies with a three-dimensional effect. A cylindrically embossed lenticular screen is placed in contact with the film and a shutter behind the lens is arranged to scan the subject during exposure.

X ray are electromagnetic radiations beyond ultraviolet which, when passed through a solid object and allowed to act upon a sensitive emulsion, form a shadow image of the internal structure of the object.

X ray film is spectral sheet film for radiography, having a thick emulsion coated on both sides of the support to increase the absorption of X rays.

X setting (X sync) is the setting that causes the flash to burst in synchronization with the shutter. For some manual cameras, the X synch speed refers to the maximum speed that the camera can synchronize with the flash.

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Photo Glossary - Y

Yellow is the color formed by mixing red and green light. Yellow is complimentary to blue, and is one of the three colors used in subtractive color synthesis.

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Photo Glossary - Z


Zirconium lamp is an arc lamp used in powerful enlarges and projectors.

Zoetrope is an early device for creating illusion of continuous motion. A sequence of still pictures was viewed so quickly through slits in a rotating drum, that the images appeared to merge.

Zone focusing is a method of focusing the lens so that the depth of field extends over a preselected range of distances.

Zone system is the method of determining exposure and development required for individual scenes, invented by Ansel Adams. It is based on analysis of subject luminosities in terms of ten gray tones, labeled zones 0 through X and previsualizing them as print densities. By measuring each subject luminance with a hand meter it is possible to determine how much the range of values must be contracted or expanded by negative development control to give the required values in the print.

Zoom lens is a lens which is constructed to allow continuously variable focal length within a specific range. The effective aperture and focus settings remain unchanged throughout such adjustments.

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