Definition: Exposure Value: scale used to measure camera exposure: for a given EV, there is set of shutter and apertures settings all of which give nominally the same camera exposure. * In normal use the scale runs from about EV-1 to EV18: EV-1 is equivalent to a setting of 4sec at D/1.4, 8sec at D/2 etc. EV18 is equivalent to 1/500sec at D/22 or 1/1000sec at D/16 etc. Note no reference to film speed. Ever useful EV numbers were formerly used widely as the means of translating read-out of exposure meters into camera exposure settings. They can even now be found on some cameras, notably Hasselblad. * Also, with film speed quoted, EV was used to give general indication of brightness level to describe e.g. operating limits of exposure meters e.g. "readings from EV-3 to EV21 at ISO 100" or auto-focus cameras e.g. "autofocus works down to EV1 at ISO 100".
Related Terms: value
Previous Term: etalon Next Term: evaluative metering