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.

Slides, Negatives, and Digital

Back in the days when film ruled, most professional professionals worked with color slides instead of negatives because clients demanded them. Why? WYSIWYG! What you saw was what you got; it was easy to judge the quality of slides, and when they were good, they were really beautiful. Projected slides can reproduce a brightness range of 1000:1 (a logarithmic density range of 3); the best you can do with a print is about 100:1. It's difficult to judge anything from a negative; prints from camera shops or drug stores seldom do justice to the information on negatives.
Why then would a serious photographer choose to work with negatives? Because negatives can capture a much larger exposure range than slides. (See What exposure range can film capture?, below.) You can make excellent images in difficult lighting that would defeat slide film. Modern negative films are as sharp as slide films of comparable speed (possibly sharper), though not as fine-grained. With affordable scanners, image editing programs and color printers, you can produce inexpensive prints of impressive quality— often better than custom darkroom prints, especially when difficult manipulations (dodging, burning, selective color shifts, etc.) are required. Scanners work well with properly exposed slides of low to moderate contrast, but if you work in the field with difficult or contrasty lighting, negatives have an edge. And difficult lighting can sometimes produce the finest, most dramatic images.
Since this article was first published, digital has overtaken 35mm and medium format film, though it still can't equal large format for detail. Digital SLRs (which have pixel sizes of at least 5 microns; larger than compact digital cameras) have impressive dynamic ranges: 10 or more f-stops, comparable to negatives and far better than slides. But as we shall see, digital images need to be exposed more like slides than negatives to avoid losing highlight detail. "Expose for the shadows" applies only to negative film (color or B&W); not to digital.

A simplied Zone System

This tutorial on the Zone System, written by Norman Koren, will be of primarily interest to newcomers to photography who use negative film — either colour or B&W. Even experienced transparency users will find it of interest as a review of an often misunderstood topic. — Michael Reichmann
Why Negatives?Most professionals work with color slides instead of negatives because clients demand them. Why? WYSIWYG! What you see is what you get; it's easy to judge the quality of slides, and when they're good, they're really beautiful. It's difficult to judge anything from a negative, and prints from camera or drug stores rarely do justice to the information on negatives.
Why then would a serious photographer choose to work with negatives? Because negatives can capture a much larger exposure range than slides. (See What exposure range can film capture?, below.) You can make excellent images in difficult lighting that would defeat slide film. Modern negative films, such as Kodak's new Supra series, are as sharp and fine grained as slide films of comparable speed. And we now have affordable scanners, Image editing programs and color printers that enable you to produce inexpensive prints of impressive quality — as good as custom darkroom prints most of the time, and better when difficult manipulations (dodging, burning, selective color shifts, etc.) are required. These scanners work well with properly exposed slides of low to moderate contrast, but if you work in the field with difficult or contrasty lighting, negatives have the edge. And difficult lighting can sometimes give you the finest, most dramatic images.
Introduction to The Zone SystemThe 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.
Ansel Adams developed the zone system to cope with this situation. 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,
"Expose for the shadows; develop for the highlights."(Warning: This rule applies to negatives, not slides; more later.)Ansel Adams used a view camera and developed each sheet film negative individually. His system is very elegant — it produces prints with exceptional tonality — but it requires a tremendous amount of testing, calibration, record keeping, and time. It's not practical unless you have a darkroom. With my day job I don't have that kind of time. Luckily there are shortcuts to making good exposures.
We present a simplified zone system that will enable you to expose your image correctly most of the time. It works equally well with color and black and white negatives; exposure technique is identical. Once you get the hang of it, you'll find it's not all that complex.
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.