Ansel Adams and Zone System. Such questions are not automatically answered by meter readings. They require an interpretive analysis of exposure (often coupled with the use of filters). Such a sophisticated approach to exposure turns out to be simpler than it seems, thanks to the "zone system" developed by the noted California black and white photographer Ansel Adams. Adams' system is based on a black and white printed "gray scale" like the sample opposite (they can be bought from most black and white camera stores and sometimes come with exposure meters). Its 10 distinct shades of gray show the range of tones, or zones, that the black and white print encompasses. These various zones can be compared-either from memory or from the actual scale - to tones in essential elements of the scene. Then exposure is set to reproduce those elements in desired zones.
The zones are numbered from 0, deep black, resulting from no exposure on the corresponding part of the black and white negative, to 9, paper white, a dense section of the black and white negative. Each succeeding zone (after zone 1) represents a doubling of the exposure of the previous zone-an increase of one f-stop. Obviously, the
average tone in the average scene is a medium gray-zone 5-and in the average black and white picture it should appear as zone 5. This is what all reflected-light meters are designed to accomplish; they indicate exposures that will reproduce as zone 5 any light intensity they measure. Only in the middle zones-3 through 7 -is detail clear.
How the zone system helps deterŽmine exposure can be seen in the black and white picture opposite, on which numbers inŽdicate the zones for various areas. The light shadows under the decks are zone 5 and a reflected-light meter reading of this area would have indicated the exposure for this black and white negative. This exposure gave detail in the cloth cover (zone 2), but made the stairs (zone 9) too bright for clarity and the reflection of the hull (zone 1) too dark. Suppose some detail had been essential in the zone 1 reflection. By opening the lens one stop, the black and white photographer would have shifted one zone up the scale, making some slight detail visible. But all other areas would be lightened similarly; zone 0 might disappear, and the zone 8 wall area would probably be indistinguishable from the stairs which are in zone 9.
How the zone system helps determine exposure can be seen in the black and white picture opposite, on which numbers indicate the zones for various areas. The light shadows under the decks are zone 5 and a reflected-light meter reading of this area would have indicated the exposure for this black and white negative. This exposure gave detail in the cloth cover (zone 2), but made the stairs (zone 9) too bright for clarity and the reflection of the hull (zone 1) too dark. Suppose some detail had been essential in the zone 1 reflection. By opening the lens one stop, the black and white photographer would have shifted one zone up the scale, making some slight detail visible. But all other areas would be lightened similarly; zone 0 might disappear, and the zone 8 wall area would probably be indistinguishable from the stairs which are in zone 9.
Ansel Adams and Zone System - Adams' system is based on a black and white printed "gray scale". Results in perfect black and white negatives.