D-type AF Nikkor lenses (Only apply to Nikon):- AF Nikkor lenses that send Distance Information to some of Nikon's top cameras, Used for 3D Color Matrix Metering or 3D Multi Sensor Balanced Fill Flash (with Nikon SB 27/SB 26/SB 25 Speedlight). Some third party lens manufacturers are catching up to supply with compatible functions lenses too.
DC (Defocus Image control):- A new type of lens family introduced by Nikon, designated as DC lens. Mainly for portrait photography. The lens enables to control background and foreground blur precisely, resulting in strikingly attractive portraits.
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:- A lighttight area used for processing films and for printing and processing papers; also for loading and unloading film holders and some cameras.
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:- colour 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.
Data Disk:- A circular, rotating disk at the end of Advanced Photo System film cassettes that functions as a circular bar code, communicating the film speed, type and exposure length through a sequence of reflective bars to an optical sensor in the camera.
Dedicated Flash:- A fully automatic flash that works only with specific cameras. Dedicated flash units automatically set the proper flash sync speed and lens aperture, and electronic sensors within the camera automatically control exposure by regulating the amount of light from the flash.
Definition:- The clarity of detail in a photograph.
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:- An instrument used for measuring the optical density of an area in a negative or print.
Density:- The blackness of an area in a negative or print that determines the amount of light that will pass through it or reflect from it. Sometimes referred to as contrast.
Depth of Field:- The amount of distance between the nearest and farthest objects that appear in acceptably sharp focus in a photograph. Depth of field depends on the lens opening, the focal length of the lens, and the distance from the lens to the subject. The zone of acceptable sharpness in front of and behind the subject on which the lens is focused; extends approx. one-third in front of and two thirds behind the in-focus subject; dependent on three factors: aperture, focal length, and focused distance; the wider the aperture, the longer the focal length, and the closer the focused distance, the less the depth of field, and vice versa; in comparison to a normal lens, wideangle lenses have inherently more depth of field at each f-number and telephoto lenses have less.
Since this element is very important, another simpler way to explain this is the amount of distance between the nearest and furtherest objects that appear in acceptably sharp focus in a photograph. Depth of field depends on the lens opening, the focal length of the lens, and the distance from the lens to the subject or can explain as in simpler term as the zone of sharpest focus in front of, behind, and around the subject on which the lens is focused; can be previewed in the camera - very handy for critical work. Relating article in this site: Depth of field.
Depth of Focus:- The distance range over which the film could be shifted at the film plane inside the camera and still have the subject appear in sharp focus; often misused to mean depth of field.
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:- A solution used to turn the latent image into a visible image on exposed films or photographic papers.
Developing Tank:- A lighttight container used for processing film.
Diaphragm:- Lens opening. A perforated plate or adjustable opening mounted behind or between the elements of a lens used to control the amount of light that reaches the film. Openings are usually calibrated in f-numbers. An adjustable device inside the lens which is similar to the iris in the human eye; comprised of six or seven overlapping metal blades; continuously adjustable from "wide open" to "stopped down"; controls the amount of light allowed to pass through the lens and expose the film when a picture is taken; a]so controls the amount of depth of field the photograph will have; in lenses designed for single-lens reflex cameras, there are basically two types of diaphragms: Lens opening. A perforated plate or adjustable opening mounted behind or between the elements of a lens used to control the amount of light that reaches the film. Openings are usually calibrated in f-numbers. The more blades used will have a more natural and rounded spots. There are two types of diaphragms:- Automatic: The most popular type; controlled by a single aperture ring; during viewing and focusing, the diaphragm remains wide open, allowing the maximum amount of light to go to the viewfinder for a bright and easy-to-focus image; at the instant of exposure, it stops down automatically to a particular aperture and then reopens to full aperture immediately afterward.Manual Preset: Used in some specific lenses like, PC-Nikkor lenses for Nikon for instance; controlled by two separate rings; the preset ring is first set to the desired aperture, then the aperture ring is rotated to stop down the diaphragm manually for metering or prior to taking pictures.
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.
Diffusing:- Softening detail in a print with a diffusion disk or other material that scatters light.
Diffusion-Condenser Enlarger:- An enlarger that combines diffuse light with a condenser system, producing more contrast and sharper detail than a diffusion enlarger but less contrast and blemish emphasis than a condenser enlarger.
Diffusion Enlarger:- An 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; negative blemishes are minimized.
DIN:- Deutche Industrie Norm (Film speed rating defined by the Deutscher Normenausschuss (German standards organisation). Numeric rating used to describe emulsion speed for German Made photosensitive materials. Just as the same as ASA and ISO numbers.
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:- The property of materials which have a refractive index that varies according to the wavelength of light, i.e., bend the rays of some colors more than others; a prism placed in the path of a ray of white light bends the blue and violet rays more than the orange and red, so that it spreads out or "disperses" the colors as a continuous spectrum.
Distortion:- Even if the other possible aberrations were totally eliminated, images could result that still have a distorted appearance. For an example, an rectangle may appear as a barrel or pin cushion-shaped object. A lens aberration which does not affect the sharpness of the image, but alters the shape of objects; the inability of a lens to render straight lines perfectly straight; does not improve by stopping down the lens; there are two types of distortion: Barrel: Straight lines are bowed in at the edges of the picture frame re sembling the sides of a barrel; pres ent in small amounts in some wideangle or wideangle-zoom lenses, bu~ uncorrected in fisheye lenses. Pincushion: The opposite of barrel distortion; straight lines are bowed in toward the middle to resemble the sides of a pincushion; present in smal amounts in some telephoto and telephoto-zoom lenses.
Dolly:- frame with lockable wheels, designed to support s tripod, and allow easy movement around a studio.
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.
Dodging:- Holding back the image-forming light from a part of the image projected on an enlarger easel during part of the basic exposure time to make that area of the print lighter.
Double Exposure:- Two pictures taken on one frame of film, or two images printed on one piece of photographic paper. Photographer. Two pictures taken on one frame of film, or two images printed on one piece of photographic paper. Some cameras can have double exposure level depressed with multiple exposures one even with a motor drive.
Drop-in-Loading (DIL):- Film cassette loading feature in all Advanced Photo System cameras that virtually eliminates film-loading problems by automatically accepting the leaderless cassette and thrusting the film forward to the first unexposed frame without any user intervention.
Dropouts:- Those black or white streaks, spots, and comets zipping across the screen. We count as dropouts any loss of playback signal that is 20 decibels or more below the nominal playback level (16 decibels for extra high-grade and 8mm tapes) and lasting for 15 microseconds or longer (about one quarter of one horizontal scan on the TV screen).
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 colours or any two colours considered visually harmonious.
Dye coupling:- process creating a coloured image from the reaction between by-products of color development and couplers.
Dye destruction process:- method of producing a coloured image by partially bleaching fully formed dye layers incorporated in the sensitive material.
Dye-image monochrome films:- black & white negative films designed for colour 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 colour 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.
DX Data Exchange:- Electrical coding system employed in 35 mm format film that communicates film speed, type and exposure length to the camera.