Photo Glossary

Daguerreotype

Photo process developed by Joseph Daguerre that produces an extremely grainy, gray or sepia-toned (brownish) image. Presently used to artificially convey age.

Darkfield

It is the 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

A removable plastic or metal sheet that slides into a sheet-film holder or film magazine to protect film from light when the holder is removed from the camera.

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.

Dedicated flash

A portable flash gun that couples to an automatic camera and can be controlled by the cameras programmed functions.

Definition

The clarity of detail in an image.

Densitometer

An instrument used to measure the density of film or paper images.

Density

A numerical measure for the darkness of a tone.

Depth of field

The distance between the farthest and nearest points which are in focus.

Depth of focus

It is a distance which the film plane can be moved while maintaining an acceptably sharp image without refocusing the lens.

Diaphragm

This is another term for aperture.

Diffraction

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

Diffuse lighting

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

Diffuser

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

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.

Digital camera

A device that captures an image on a CCD so that the image file can be downloaded to and manipulated by a computer; does not use conventional film.

Digital image

An image composed of pixels.

Digitization

The process of converting analog information into a digital format for use on a computer.

DIN

Stands for Deutsches Institut für Normung, the German Institute for Standardization.

Diopter

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

Dispersion

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

Distortion

An alteration in shape and proportions of an image.

Dithering

Dithering scatters different colored pixels in an image to make it appear as though there are intermediate colors in images with a limited color palette.

Documentary photography

Taking of photographs to provide a record of social and political situations with the aim of conveying information.

Dodge

To lighten a small area of the picture in an image editing software or a darkroom.

Dodging

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

DPI

Short for dots per inch. DPI measures the resolution of a computer monitor, scanner or printer. The more dots that are placed per inch, the higher the image quality, providing, of course, the image is sharp in the first place. The typical resolution of a computer monitor is 72dpi for a Mac and 96dpi for a PC. Entry-level digital printers lay around 600 dots per inch while photo quality printers are 1200dpi or higher. Scanners range from 300dpi to around 4000dpi.

Duotone

An offset printed image created with two different colors of ink.