zone system

Definition: Technique or methodology for camera exposure and development control of black & white materials based on the concept of change of density in steps of one whole stop change in exposure - the 'Zone'. * Nominally, there are 10 Zones; in practice a very good print exhibits perhaps 9 zones. * Zones are numbered 0 to X: Zone I is shadow with no detail, Zone V is middle grey in a print, Zone X is highlight with no detail visible. * Each step represents a difference of one stop in exposure e.g. from f/4 to f/5.6 with constant shutter time, or 1/30sec to 1/60sec with constant aperture. * Enunciated by Ansel Adams, refined by Minor White.

Previous Term: zone plate  Next Term: zoom