PHOTOGRAPHY GLOSSARY (C-D)
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
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
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
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
Capping shutter - extra shutter used in some medium
format cameras or in conjunction with a group of extreme high
Carbon arc - see Arc
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
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
Catadioptric lens - see Mirror
Catchlight - reflection of a light source in the
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
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
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
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
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
Chromogenic development - process in which the oxidation
products of development combine with color couplers to form dyes
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
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
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
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
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
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
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
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
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
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
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
Compur shutter - well known German brand of compound
Concave lens - see Bi-concave
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
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
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
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
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
Convex lens - simple lens
which causes rays of light from a subject to converge and form
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
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
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
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
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
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.
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
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
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
Desensitizing - reducing an exposed emulsion's sensitivity
to light. This can be done by the application of dyes or by using
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
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
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
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
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
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
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
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
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.