Introduction to the Zone system

The first thing you need to know is that exposure meters are dumb, really dumb. They are clueless about what they're photographing. They assume that all scenes have the same average tonal value— middle gray— roughly zone 5 in the chart below. If a scene is different, for example a snow scene, it will be exposed incorrectly. It will come out middle gray— underexposed. If you follow the meter's reading, every scene will have the same average middle gray density. You'll get lots of bad exposures, especially if you photograph in difficult light.


An exception to the dumb exposure meter rule can be found in modern single lens reflex cameras with matrix metering, which tend to be expensive high-end models. A good example is the Nikon F100, which has a 10 segment meter. It meters each segment individually, then uses a computer program to determine the optimum exposure. The program employs artificial intelligence or fuzzy logic— it's been taught to respond correctly to a wide variety of scenes. Of course there will always be exceptions— a reader's comment in the photo.net review of the F100 indicates that it can be fooled by backlighting, but it can be trusted most of the time.


Ansel Adams developed the Zone system to cope with this situation (see history, at the bottom of the page). His technique was to carefully study a scene, visualize the final print, then determine the correspondence between portions of the scene and tones in the print. He would then meter, expose and develop the negative accordingly. His basic rule was,

Adams used a view camera and developed each sheet film negative individually, based on the scene contrast and the previsualized print tonalities. The greater the contrast in relation to the print, the shorter the development time. His system is very elegant— it produces prints of exceptional tonality, and most images print on a single grade of paper (Adams preferred grade 2), but it requires a tremendous amount of testing, calibration, record keeping, and time. It's not practical unless you have access to a darkroom and plenty of time.
We present a simplified Zone system that will enable you to make excellent exposures. The technique is identical for color and black and white negatives, but different for slides and digital, where it can be used to find a starting point for bracketing (for critical work). Once you get the hang of it, you'll find it's not all that complex.