ZoneSystem

Zone System is an exposure control system used in black and white photographic printing. It involves varying the contrast in an image by adjusting the range of tones across a print. This is typically achieved by dividing the print into three or four zones, each with a distinct tonal value.

The Zone System was developed by Ansel Adams in collaboration with Fred Archer in the 1930s. It is based on the principle of creating a print that has the maximum possible range of tonal values, from pure white to pure black, with a step set of neutral points in between. These zones are usually numbered, starting from zone 0, which is the pure black, and up to zone X, which is the pure white.

Each zone in the system has a specific light value, expressed in a system of steps, from 0 to 18. Zone 0 is pure black, while zone X is pure white, with an 18-step range of mid-tones in between. The tonal range of an image is controlled by using silver gelatin prints, which allow for a maximum of 18 steps in the print.

A photographer using the Zone System must control the contrast of the image during the negative stage, by adjusting the exposure, contrast, and density of the paper. The printer then adjusts the amount of time that light is allowed to expose the print, to achieve the desired contrast. Despite its technical nature, the Zone System allows for a high level of creative control and can produce very pleasing results, with a range of tonal values that far exceeds that of standard printing processes.