Tuesday, February 9, 2010
The Digital Zone System
If you thought DSLRs and new technology made the Zone System obsolete, think again. Updating the classic Ansel Adams tool for proper exposure will make your digital photographs as good as they can be.
The heart of the traditional Zone System is the ability to expand or contract the contrast range of the negative—to increase contrast and add impact to low-contrast images or reduce contrast to hold detail in both highlights and shadows in high-contrast scenes.
Blending Images: Exposure In The Field
To blend exposures later, you first have to capture all the necessary information in the field. Make sure the camera is on a sturdy tripod to avoid camera movement between frames. Next, use the Zone System, or any method you prefer, to get a good exposure for the highlights. Check the histogram to make sure the brightest pixels are near, but not touching, the right edge, and adjust if necessary.
Then make another exposure one stop lighter, and another, and so on, until you see space between the darkest pixels and the left edge of the histogram. You’ve then captured detail in both highlights and shadows, plus a full range of tones in between. The histograms below show what this might look like.
Ansel Adams used reduced development to capture highlight and shadow detail in high-contrast scenes, but he was well aware that this could lead to flat, mushy areas in the midtones. The same problem confronts digital photographers when blending exposures. Too much tonal compression can reduce local contrast and produce a lifeless image. When comparing different methods of merging exposures, pay attention to those midtones and make sure they have some contrast and snap.
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