The Simplified Zone System © Wendy Folse Nov 12, 2001
When Ansel Adams perfected his Zone system, he took into account every part of his photographic system and then measured and quantified each process. This allowed him to be able to precisely predict how each scene could be reproduced within his system. The major point of focus that must be remembered is that Ansel Adams was using sheet film, not 35mm film. His system worked because he could shoot and develop each negative using his precise calculations. This does not work well for 35mm film because in order to control the precise development of each frame, they would all have to be shot with the exact same exposure values. Today the Zone system is still much talked about and in some forms it is still used as Ansel Adams intended it to be used. However, it is most often used as a method for determining exposure values based on tonal ranges of a scene. It is difficult to condense the entire Zone system into a few words and display it here but I will try to give you an easy "take what you will" example. The Zone system breaks the range of light values into 10 zones from key black to paper white. Each zone represents one f‐stop.
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Zone 9 pure white +4
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Zone 8 white with little detail +3
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Zone 7 greyish‐white highlights +2
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Zone 6 light grey +1
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Zone 5 18% grey 0
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Zone 4 darkish grey ‐1
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Zone 3 blackish grey ‐2
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Zone 2 greyish black some texture ‐3
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Zone 1 Black with little detail ‐4
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Zone 0 key black no detail ‐5
That amounts to a range of 9 stops. Not all films, especially 35mm, can handle nine stops nor can the paper. So the whole idea is to use the scale to move the desired tonal range within an acceptable range. We know that all meters give exposure values based at 18% grey (Zone 5). If you metered on black skin, the meter would give you a reading in order to render the skin color 18% grey. That will not make the client very happy. So where do you put the skin tone to be most accurate? At about Zone 4. That means that you would take the exposure reading from the meter and then set the EV for ‐1. For Caucasian skin it should fall at about Zone 6. (+1) For Pale Northern European Skin types it would be Zone 7 (+2) The purpose for spot reading the shadows and the highlights is to understand the total range of the scene and then decide which points are important and which ones are less important. Obviously a person's face is more important so you would set the exposure for that feature. Then you figure out what details you will lose in the process. You may add light to the scene to increase the zone of a shadow detail in order to move it into an appropriate zone. Green grass is about Zone 5 Weathered Wood is also about Zone 5 A black Tux is about Zone 3 A white bridal gown is about Zone 7 Since you know that negative films have a greater latitude for overexposure than for underexposure this is where we get the old addage, shoot for the shadows. Place your darkest important points first and then adjust to get in the max range. The whole modern idea about the Zone system is to give you a tool to Previsualize a scene before shooting. Then you learn to alter the development process in order to extend the range if necessary. "Expose for the shadows, develop for the highlights." So if you have exposed your film according to the Zone system of tonal ranges and have shot for the shadows, then you alter development times to get more tonal range on the film than it may normally handle. Example: If your scene has a brightness range of 5 stops, then process normally If you have a scene with 7 stops, cut development time by 40% If you want to compress the scene down to only 3 stops, then develop for twice the normal time. This is where the problem comes in. Altering development only works if you shoot sheet film or if the entire roll has been shot exactly the same. So today the Zone system is most often used as a pre‐ visualization tool only. "Where to place which zones." Learning how each zone is rendered in the final print will give you an excellent basis to use in order to pre‐visualize any scene and render it in such a way that incorporates as many of the tonal ranges as possible. One excellent, but older resource for learning the Zone System is Minor White's, Zone System Manual.