Barry Pehlman , Jun 09, 1998; 09:59 a.m.
Exposure value (EV)is a range of f-stop, shutter speed combinations by a single setting that yield the same exposure. "For instance, the exposure value 13 gives a range of aperture/shutter speed combinations- e.g., 1/500 sec. at f4, 1/250 sec. at f5.6, or 1/125 at f8- each of which gives the same amount of exposure. A scale from 2-18 is sufficient for all normal photographic purposes, since it represents exposures from 1 second at f2 to 1/500 second at f22; in other words a range of over 1:60,000". (Focal Encyclopedia of Photography)