zone system

Zone System - A Photography term, used to describe a method of exposing film in such a way as to get the desired expsure that catches all details that the photographer wants.

Quick description: An image (or view) is broken up into lighting zones, which span from black to white. The photographer will set the exposure to ensure that both dark gray and near-white are both captured on the film. If the exposure is not set properly, (under) then dark-gray would show up as black, or (over) then near-white would show up as white. All detail in these areas will be lost, and can not be reproduced on the final print.

Overexposing or underexposing can be used to increase or decrease the number of 'zones' available, and essentially decreases or increases the contrast of the image.

Printing can be adjusted to get the desired effect from properly exposed film by varying exposure time and paper type (high-contrast or low-contrast).

Ansel Adams is one of the best examples of a photographer who used the zone-system to set his exposures. He used his creativity and imagination to create an image in his mind. He would then use the 'zone system' method to achieve that image on film and print. He as a Genius in this respect!

Notice, though, that this is practical only with large format, where film comes in sheets that you can individually develop. A spot meter is also handy.

Ansel Adams actually invented the Zone System: he always stressed the importance of previsualization for the photographer.
The Zone System (and Adams' photography) is about absolute image control. You are master of what ends up on paper.

It also worth observing that the Zone System in all its might only really works for Black and White, where you can pretty much play around with development times and fluids.
In color, you have much less freedom with the negative: you can still modify things when printing, though.