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Apogee Photo Magazine

Using the Zone System in the Field

by Bob Hitchman

Great Basin National Park, in eastern Nevada, was at the peak of autumn color as I photographed the aspen groves on Wheeler Peak last September. The end of the paved road, at 10,000 feet, was surrounded with dense yellow groves of straight-trunked trees beneath a clear blue sky. I was shooting Fuji Astia, a professional color slide film with very realistic and natural color but slightly lower-than-normal contrast. I wanted to capture the whole range of light across the scene I was photographing–from the dark shadows beneath the trees to the highlights on the yellow leaves and the clouds above the summit of Wheeler Peak. I often make prints from my slides and sometimes scan these slides, convert them to black and white, and use the images in my Photograph America Newsletter. Controlling excessive contrast is a never-ending problem.

In this scene I placed the highlights of the aspens at Zone VII. Other values in the same scene, that fell within the film’s latitude range, were properly exposed.

I often use a simplified version of Ansel Adams’ Zone System to double-check the exposure readings I get with the matrix metering system in my Nikon 8008s. With a hand-held, one-degree Pentax spot meter, I took close-up readings of the aspen trunks. I wanted to properly expose the bright autumn scenes on Wheeler Peak. There is a fine, dusty texture covering aspen trunks that is too easy to loose by over-exposure. A straight meter reading would give me an exposure that would under-expose the light trunks and the bright yellow foliage. I did not want the trunks to appear middle gray. By increasing the spot meter reading off the trunks by 2 stops, I was able to retain all the details in the highlights, including the clouds drifting over the summit. I could have achieved the same results by setting the exposure compensation dial on my 35mm camera to +2. The great advantage of the one-degree spot meter, is that it reads a very narrow angle. A photographer can be very selective in taking exposure readings of very small areas. Most light meters take in a wide field of view and will give an average reading of that general area.

After setting the proper ISO for the film I’m using, I point my hand-held spot meter at the subject and place the small dark circle (a 1° angle of coverage) in the viewfinder over the desired area in any scene. Pressing the button on a digital spot meter lights up a red LED number. Pressing the button on an older-style analog meter, moves a needle to line up with a number on a scale–usually from 1 to 19. That EV (exposure value) number in the viewfinder represents the reflectance–the lightness or darkness–of a specific area in any composition. By rotating the meter’s dial and lining up that EV number with the index mark or whatever type of reference point is used on the meter, the meter gives its recommendation of the correct exposure setting. The correct exposure might be a high shutter speed and a large f-stop or a long exposure time with a small aperture–or anything in between. The resulting exposure will be just an average that will reproduce the area measured as middle gray. This is the same way all light meters operate. They have no brain and can’t tell whether a subject is black or white or middle gray or some other color in between. A light meter can only give you an exposure setting that will reproduce the area metered as middle gray. From there, it’s up to the photographer to interpret the scene and determine whether to compensate. Darker subjects require less exposure and lighter subjects require more exposure–to avoid reproducing them as "middle gray."

The key to the use of Ansel Adams’ Zone System is the visualization of the final print or transparency before an exposure meter reading is made. Instead of compensating for an exposure reading after it is metered, a photographer determines before taking a meter reading exactly where, on a scale from pure black to pure white, a certain part of a composition, landscape, scene, portrait. etc., should be placed. A close-up meter reading of an 18% gray card should be placed on Zone V–exactly half-way between black and white. The clear north sky, weathered wood, gray stone, green grass should usually be placed on Zone V. Dark stone, dark foliage, landscape shadows, unbleached demin, etc. can usually be placed on Zone IV (one stop darker than middle gray). Caucasian skin, shadows on snow, light stone, sand dunes and other subjects with similar lighter-than-middle gray areas can be placed on Zone VI.

Ansel Adams’ Zone System is a very useful method of exposure when used with a spot meter. Several brands of hand-held spot meters can be modified with the simple addition of a Zone System scale printed on a sticky label. When attaching the paper scale to your meter, the center of Zone V is placed directly over your meter’s reference point or index mark.

After visualizing the final image, a photographer takes a close-up spot meter reading of an area that is determined should be placed on a particular zone. I wanted the white trunks of the aspen trees to appear in the final image as white, but still retaining a bit of visible texture. With some practice, I know that means Zone VII. After setting the EV number that appeared in my meter’s viewfinder opposite Zone VII on my scale’s meter, the meter displayed a combination of f-stops and shutter speeds. I selected the f-stop that gave me the depth-of-field I needed for the aspen scene and used the shutter speed opposite that f-stop.

I placed the highlights in the aspen scene on Zone VII. Other values in the same scene, that fell within the film’s latitude range, were properly exposed. It is possible to expand or contract the contrast range of some black-and-white films by over or under development. This works best when using large format sheet films or when using removable, interchangable backs on a medium format camera since a whole sheet or roll of b/w film must be processed using the same developer time. This type of contrast control is not possible with color negative films. Ansel’s Zone System also involves the visualization of the entire scene, including the expansion or contraction of the range of zones. A more contrasty scene has fewer zones, a less contrasty scene has more zones. If, after placing the shadows of a scene on a particular zone, it is determined that the scene’s highlight details will fall on a zone that will reproduce them as too light and lacking in detail, it is possible to decrease the development time of that sheet of film and decrease the contrast of the negative. Ansel used the designation Normal-Plus or Normal-Minus development.

Since this additional use of the Zone System to control contrast is only useful when shooting large format black-and-white sheet films, I only use the Zone System to increase the accuracy of my exposures on color slide film and color negative film. I am not able to control my film’s contrast ranges and therefore do not manipulate the development time of my films–mostly roll films and color films.

All this information can be simplified and easily used for exposing color slide films and color print films in this way:

When I’m exposing color transparency film, I always want to avoid over-exposing the highlights and washing out details in the lightest areas of a composition. I take a spot meter reading of the brightest area that I still want to retain detail and place that reading on Zone VII.

When I’m exposing color negative film, I always want to avoid under-exposing the shadows and losing details in the darkest areas of a composition. I take a spot meter reading of the darkest area that I still want to retain detail and place that reading on Zone III.

Basically, those two simple tips will allow you to greatly improve your exposures using the Zone System. Visualizing your final exposures does take some practice but it is the key to the use of the Zone System. Ansel Adams’ book, "The Negative," has an excellent chapter on the Zone System. Inexpensive zone scale sticky labels for your hand-held spot meter can be purchased from Calumet Photographic. Call 1-800-Calumet to order a zone scale label.

For more information about photographing Great Basin National Park,check out Robert Hitchman’s PHOTOGRAPH AMERICA NEWSLETTER.