Data

Factual piece of information (as measurements or statistics) used as a basis for reasoning, discussion, or calculation. Information output by a sensing device or organ, it includes both useful and irrelevant or redundant pieces of information that must be processed to be meaningful in a decision making process. Information in numerical form that can be digitally transmitted and/or processed. "Don't confuse me with the data, give me information to make decisions".

Daylight

Ambient light with a color temperature of 5500K. Direct sunlight on a bright day, at noon time, combined with the reflected light from the sky, produce natural ambient light.

Daylight-Type film

A film designed to render a natural, correct color balance when exposed in daylight.

D chip

Relays distance information from a Nikkor or Nikon-D-compatible lens into a Nikon camera body, which in turns relays it -after processing it with metering data- to a Nikon speedlight for ultra-precise fill-flash.

DC (Defocus Control)

Unique ability of a Nikkor lens to alter the shape of its out of focus areas, both foreground and background via aberration management, like in the Nikkor 105mm f/2.8D DC AF and 135mm f/2D DC AF. This feature creates splendid boke.

Definition

Sharpness of an image (as seen by the clarity of detail) formed by an optical system.

Darkcloth

Dark material used to cover the photographer's head and the ground-glass-viewing screen on large format cameras.

Darkroom

"Dark," light-tight space for processing and printing photographic materials.

Darkslide

Thin, flat piece of metal or plastic, which protects unprocessed film from light exposure.

Dedicated Flash

Electronic flash designed to work with the meter and exposure system of a specific camera.

Density

The amount or "density" of silver on an exposed and processed piece of film.

Depth of Field (DOF)

The distance between the farthest and nearest points which are in focus. This can also be identified as the zone of acceptable sharpness in front of and behind the subject, to which the lens is focused on. DOF varies according to numerous factors such as lens focal length, aperture, shooting distance, etc.

Depth of Field Preview Button

When actioned, it closes down the aperture of an auto lens to that of the selected exposure, allowing (a darkened) view of the depth of field through the viewfinder.

Developer

Chemical that converts silver on film to visible, black image.

Diaphragm

Another word for aperture. Can also be a type of shutter. Refer to Leaf Shutter.

Diffraction

Bounced light. Light "refracts" off opaque materials softening and blurring an image.

Diffuser

Material that softens and "diffuses" light in order to soften the edges in an image.

Digital

A device or system which can be stored and processed, where the use and representation of on/off impulses translates into 0/1 data called bits.

Digital Camera

A camera that captures an image through the lens but instead of on film, it does it on an an electronic image sensor, a CCD (Charged Coupled Device); then temporarily transferred into a FlashCard™ for eventual download into a computer.

Digitization

Transformation of analog data into digital data for computer storage and processing.

DIN

Stands for Deutsches Institut für Normung, the German Institute for Standardization. Founded in 1917, since 1975 it has been recognized by the German government as the national standards body and represents German interests at international and European standards circles. DIN is a logarithmic expression while ASA is an arithmetic one. An ISO 100 film has a DIN rating of 21; an ISO 200 film has a DIN rating of 24. The DIN number is equal to 10 times log ISO + 1 and the ISO number is equal to antilog of (DIN - 1 divided by 10), e.g. for ISO 200, log 200 equals 2.3, times 10 = 23, 23 + 1 = 24 DIN

Diopter

An optical unit of measure of the refractive power of a lens, the reciprocal of its focal length.

Disc

An optical storage device. e.g. a CD-ROM.

Disk

A magnetic storage device. e.g. a computer hard disk

Dispersion

Where light rays deviate by different wavelengths, causing a light spectrum, or rainbow.

Distance Information

As provided by the D chip on D-type lenses, relayed to the camera for processing for ultra-precise speedlight exposures on AF Nikon auto bodies.

Distortion

Where straight lines are not rendered perfectly straight in a photograph. Two types of distortion exist: barrel and pincushion.

Dodging

Selectively lightening part of a photo, either on an enlarger for traditional film printing or with an image editing program. The opposite to "Burning".

Download

Or downloading, the process of transferring computer data from one location to another, as examples: files from Internet into a computer, or digital images from the camera's memory card into a computer.

DPI

Dots per Inch. As applicable to the resolution of a printer, the number of dots it can print per inch. Erroneously it is also applied to scanners and digital cameras instead of PPI (Pixels Per Inch), as if a dot would be equivalent to a pixel. The higher the number, the higher the resolution.