Bruce Barnbaum - The Art of Photography - An Approach to Personal Expression

Since the camera is on a tripod and you have no worries about movement with a long exposure, why not also go for greater depth of field by closing down to f/8 while lengthening the shutter speed to ¼ second? ... or even going to f/11 @ ½ second? After all, the rocks won’t move, nor will the camera on the tripod. But remember, if a bush is in the scene and a breeze is blowing, you may have to rethink that approach. These are the real problems of photography.

Now you can see that the zone system becomes not only a tool for “correct”, literal exposure, but also a creative tool for departures from reality. So many people forget this aspect of the system despite the fact that it is one of its greatest virtues. All aspects of photography should be meshed for creativity and personal expression, and the zone system should be an integral part of that process. The zone system is a method of precise exposure, and that precision can be applied to literal interpretations or to vast departures from reality. It is a remarkably useful and flexible system of exposure for creative photographers.

One final example will begin to expand the concept of the zone system to its full usage. When you look at a scene, you are generally concerned with several objects and several tones, not just one. The zone system explains how to relate these tones.

Suppose you want to make a portrait of a white male wearing a dark shirt. Suppose the gray meter reading of the man’s face is f/11 @ second, and the shirt reads f/8 @ second. (The shirt is darker, thus it requires a greater exposure for a Zone 5 rendition. Brighter objects always require less overall exposure on the gray meter. Make sure you fully understand this point before going further!)

How far apart are the readings? F/8 is one zone more than f/11. second is two stops more exposure than second. Therefore, the man’s face is three stops brighter than the shirt. If you make the exposure at the reading on the man’s face, the face would be in Zone 5 and the shirt would automatically be in Zone 2. Both would be too dark. If you make the exposure at the reading on the shirt, the shirt would be in Zone 5 and the man’s face would be in Zone 8. Both would be too bright.

Whatever the zone of the man’s face, the shirt is three zones lower. That cannot be changed during exposure (except possibly through filtration, which we will not consider here). So, if you place the man’s face at Zone 6½ by opening up the aperture 1½ stops above the meter reading on his face, then the shirt would end up at Zone 3½. To do this, first open up one stop from the meter reading of f/11 @ second, to f/8 @ second (or to f/11 @ second, which would be the same). This places the tone of the face at Zone 6. Then open up another ½ stop to place the face in Zone 6½. The final exposure would be halfway between f/5.6 and f/8 @ second. Now both the man’s face and the shirt are reasonably placed for a meaningful portrait.

In Chapter 9, the discussion will continue with methods of altering contrast between two objects. If a scene is too contrasty for your desires, appropriate negative exposure and subsequent development can be used to lower contrast while still maintaining detail throughout the negative. Conversely, if the scene is too flat for your purposes, appropriate exposure and development can be used to increase contrast to a more desirable level.

The Zone System for Color

In color, contrast is inherent in the film. It cannot be altered easily unless you learn very sophisticated methods of color negative or transparency development, which are beyond the scope of this book. This chapter, dealing with exposure, is therefore even more important for color than for black-and-white because it’s the only control you have. The only contrast control you have is to change from one film to another that is inherently higher or lower in contrast.

As noted in Chapter 6, most outdoor transparency films possess higher contrast than indoor transparency films or color negative films. For outdoor transparencies, one stop exposure increase or decrease will be more than one zone tonal change on the film—it may be as high as 1½ zones. This means that just two stops of exposure increase from the gray meter reading could put the average tone almost at Zone 8, just below pure white. Decreasing the metered exposure by 2 stops puts the average near Zone 2, or just above black. 2½ stops of reduced exposure yields a pure black on the most contrasty color transparencies. Even a ½ stop increase in exposure will be close to a full zone of tonal brightening. That explains why even a small exposure error on a color slide usually ruins it. For this reason, it is even more imperative to use the zone system with extreme precision for color transparencies.

Color indoor transparency film, being somewhat lower in contrast, permits more flexibility. Color negatives are even more forgiving. But remember one key point: with a negative you can correct an incorrect exposure within limits; but with a transparency, the slide itself is often the final product, and an incorrect exposure usually has no recourse.

Exposure of color negatives must be more precise than black-and-white negatives. When attempting to correct an overexposed color negative at the printing stage, you may encounter color shifts that alter the entire color balance. Underexposure of color negatives poses the same problems as it does with black-and-white negatives: loss of shadow detail. Once detail is lost in the negative, it cannot be regained in the print.

When I shoot color, especially transparencies, I am very precise in my use of the zone system. I meter extensively, making sure that I’m not exceeding the limits of the film, and that all colors and tones will be rendered just as I want them to be. If I miss by just a small amount, my transparency may be useless. I must know the latitude of the film, its inherent contrast level, and the light levels of every important object in the scene. If they are within the range of the film, I can make the exposure. If they are not, there’s no point wasting an exposure. For instance, if two objects meter two stops apart—say, f/8 @ second and f/8 @ second—high contrast transparency film would greatly expand the spread because of its inherent high contrast. The metered difference of two stops would translate to about 3 zones. With color indoor transparency film, the difference would be just over two zones (Figure 8-3). With color negative film, the difference would be at, or slightly less than, two zones.

If the scene is photographed with a high contrast color transparency film, and the brightest object is placed one stop above its metered value, it would end up at about Zone 6 ½ (because each stop represents about 1½ zones). The darker object would then be three zones lower, or Zone 3½. Thus both would be clearly visible, but the brighter one would be a very light color while the darker one would be a very deep color. With most indoor transparency films, the bright object would end up at Zone 6 and the dark object at Zone 4. Both films would show detail, but the renditions would be considerably different.