This assignment asks you to review the Zone System. The emphasis here is on exposure and print values. The theory of camera work is discussed in Basic Camera Operation and Technical Camera Issues. The definitive treatment on camera work is found in Ansel Adams's books, The Camera and The Negative. (See the bibliography.)
The Zone System
The so-called Zone System was created by Ansel Adams as a way of talking about optimum film and print exposures that produce a wide but balanced distribution of grays in the resulting image. While there are indefinitely many grays between black and white, Adams divided these into eleven systematically divided shades of gray and named these Zones, beginning with Zone 0 as pure black and Zone X as pure white. In the exact middle is Zone V which is called "Middle Gray." The system behind the actual selection of grays is determined by the standard "stops" of a camera. Thus, Zone IV is one stop removed from Zone V and so on. (The Negative, p. 50.) An exciting black&white image has wide zonal representation.
Exposure meters are calibrated to indicate "optimum exposure" on Middle Gray. That is, the camera aimed at something that is Middle Gray (e.g., a standard gray card) and adjusted for the meter's optimum exposure will produce a negative and, eventually, a print with silver density that replicates Middle Gray. In fact, if you set the camera adjustments to optimum exposure, the negative will develop to Middle Gray no matter what the camera is pointing at! If you point the camera at a bright white object and expose the film for optimum indicated exposure, the object will come out Middle Gray in the negative and print.
Herein lies the key to Adams' Zone System. When you point the camera at a specific object and set the camera adjustments to meter optimum exposure, you are, in Adams's words, "placing that object on Middle Gray (Zone V)." All other objects included in the image will "fall on other zones," depending on their luminosities relative to the object you selected. Thus, if you expose the image based on a white object, the camera will try to make that object Middle Gray and, in the process, will shut out so much light that everything else will look black; you have grossly underexposed the film. If you expose the image based on a black object, the camera will try to make that object gray and will let in so much light that it will burn out everything else to look white; you have grossly overexposed the film.
To produce an exciting image with good distribution of Zones, you can start by finding an object that you want to print Middle Gray and setting the exposure on it. (Some people even carry a gray card for this purpose.) Having placed this object on Zone V, you will discover that all the other objects in the image fall on zones ranging, on average, from Zone III up to Zone VII. A spot meter is best for this process since you can meter the light from a small portion of the image. The older center-weighted meter is all right, but you will need to be careful where you point the camera. Do not use the new "matrix metering" system if your camera offers this.
In creation of the negative, control of the blacks (lowest zones) is most important. In particular, black areas of the image can easily go completely black and lose any detail or texture. Exploration of the Zones demonstrates that, on most films, Zones 0 through I are black with no detail. Detail and texture just begin to appear in Zone II and are fully available in Zone III. Adams suggests placing any black object for which you want detail or texture on Zone III. You can do this by aiming the camera at this object (perhaps a shadow) and adjusting the camera for optimum exposure. This temporarily places the object on Zone V. To place it on Zone III, change the aperture setting (increasing the f/ number and reducing light) or the shutter speed (reducing shutter speed and reducing light) by two stops. The camera should now show that it is off optimum exposure by two exposure units or underexposed. You can explore the zonal balance of your image by watching the meter as you point the camera at other objects. If you do not see the meter return to optimum exposure on most objects and even overexposure on some, the image is not going to possess very exciting zonal representation.
Updated on August 27, 2002; click here to return to Course HomePage.