D

depth of field

The distance within a scene that records the subject on film as being in sharp focus. Depth of field is determined by the focal length of the lens, the f-stop setting, and the distance from the camera to the subject. It can be shallow or deep, and can be totally controlled by the photographer.

duplex metering

An exposure method that uses an incident meter to measure front- and backlighting values relative to the subject. The results are averaged to determine the final exposure value. This is a good method to use when an image is strongly backlit.