Ansel Adams and Fred Archer formulated the zone system to give photographers a systematic way to set the correct exposure.
Film photographers were the original users of the system; however, the technique is still relevant when shooting digital.
The fundamental concept is that exposure meters give a reading that correctly exposes middle grey.
Middle grey exposure works for most situations. However, there are exceptions:
Light tones dominate
Consider shooting a picture of a very light subject, for example, snow – since the meter gives exposure for middle grey (not nearly as bright as the subject) the reading given underexposes the subject. The underexposure is because the meter brings the luminance down to middle grey.
To get the correct exposure the photographer needs to increase the exposure by a few stops.
Dark tones dominate
Conversely, if you are shooting a dark subject, for example, dark wood, then the meter gives an exposure that brings the dark up to medium grey, again the yields the dark wood tones overexposed – so the photographer needs to reduce the exposure.
To take your shooting to the next level, start to look at the scene you are photographing and decide the tonalities you want in your picture, are the main subjects dark or light? How do you want them to appear?
Once you have decided the tonalities you want, you can use the table below to figure out the appropriate zone.
| Zone | Description |
|---|---|
| 0 | Pure black |
| 1 | Near black, with slight tonality but no texture |
| 2 | Textured black; the darkest part of the image where you can see small detail |
| 3 | Average dark materials and low values showing adequate texture |
| 4 | Average dark foliage, dark stone, or landscape shadows |
| 5 | Middle grey: clear north sky; dark skin, average weathered wood |
| 6 | Average Caucasian skin; light stone; shadows on snow in sunlit landscapes |
| 7 | Very light skin; shadows in snow with acute side lighting |
| 8 | Lightest tone with texture: textured snow |
| 9 | Slight tone without texture; glaring snow |
| 10 | Pure white: light sources and specular reflections |
There is a one stop difference between each zone. Let’s suppose you decide the primary tones are in zone 8 since that is three stops above zone 5 so you will need to increase the exposure by three stops to get the exposure right.
For example, if your meter read f16, then you would use f 5.6 when taking the picture (remember that reducing the F-stop increases the exposure).
John Unwin Photography 