Information AboutZone System |
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In Photography , the zone system is a technique invented by Ansel Adams and Fred Archer in 1939 or 1940. It is one of the earliest methods to give photographers systematic control of their images by precisely defining the relationships between their equipment and materials. While employing the Zone System as it was intended to be used can be very demanding, as it requires a consistency in procedure that is quite difficult to achieve in practice, the underlying concepts are very useful to any photographer who wishes to move beyond setting his or her camera to "P" mode. In a typical sun-lit outdoor scene, the brightest elements such as the sun, the sky, and the clouds are much, much brighter than the darkest elements like the shadows, or dark clothing. While our eyes and brains are usually capable of automatically adjusting so that we can see the details in the clouds as well as in the clumps of black soil, photographic paper doesn't have nearly the range needed to do so. The result is a photographic print with a flat, paper white sky, or a featureless black ground, or perhaps both. On a flat, gray, overcast day, the photographer may be faced with the opposite problem, and have a print with no real white, or no real black. Using the Zone System, the photographer can use exposure and film processing techniques to control the way that the light and dark in the scene map to the light and dark on the final print, so that the print appears in exactly the way that he or she intended when the shutter was snapped. Originally designed as a tool for instruction while Adams and Archer were teaching at the Art Center School in Los Angeles, Adams went on to popularize the method. While Adams' focus was on monochrome (black and white) photography using medium and large-format sheet-film cameras, where each photograph is developed individually, many elements of the method have also been applied to color and smaller roll-film formats, such as 35mm , where photographs on the same roll must be developed together. The zone system was developed in conjunction with the concept of ''visualization'' (Adams often called this "previsualization," though he later noted that the term is a redundancy). The finished print was visualized before the picture was taken, based upon the carefully measured luminosity range of the scene and an intimate knowledge of how film and print paper could render that scene. Together, the zone system and visualization allow photographers to translate the light from a scene into specific densities on negatives and paper, thus giving them better control over the finished photograph. OVERVIEW FOR MONOCHROME MATERIALS The zone system separates the picture's tones into eleven zones, numbered using Roman numerals. : 0: Pure black : I: Near black : II: Dark gray / black : III: Very dark gray - the lowest zone with distinct shadow detail : IV: Medium dark gray : V: Medium gray (equal to Kodak's 18% Grey cards) : VI: Mid-tone gray : VII: Light gray :VIII: Gray / white - the highest zone with distinct highlight detail : IX: Near white : X: Paper base (pure white) The zone system is chiefly used when exposing and processing film, and more specifically, when deciding how to render shadow and highlight areas. Briefly put, the technique involves choosing an exposure that captures the desired tone and detail in the shadow areas, and then adjusting the development time to obtain the desired highlight density. What makes the zone system so useful is the ease with which it translates desired effect to camera settings. Light Meter s will return the proper Aperture ( F-stop ) and Shutter Speed to expose the metered area at 18% middle grey - equal to zone V. Each zone above or below zone V corresponds to one f-stop. So, for example, if a photographer desires the shadow values of the ground below a bush to be a very dark tone, but still holding detail (zone III), he or she would close the aperture two stops from the light meter's reading of the shadow area. The smaller aperture results in less light hitting the film and thus in darker shadow areas. A simplified technique for applying the zone system in practice is as follows. Using a spot meter, read the f-stop from an area of the image you are capturing that falls into zone III. Take a second reading, this time from an area falling into zone VIII. If the f-stops are within 3 or 4 stops, split the difference, setting your f-stop using the value that falls between the two extremes. In most cases, this will result in an exposure that captures the range between zones III and VIII. If the range is too great (e.g., a picture of a black cat in white snow), darkroom techniques (e.g., extended development using a weaker than normal developer) are required to stretch the range. It is important to note when using the zone system that the range of traditional photographic materials is rather limited, and the ability to capture images extending the entire range of zones defined by the zone system is not typical. FILM Monochrome (black and white) film can record a light intensity range of about seven zones. The luminosity range available within a scene, however, from the darkest shadows to the brightest areas, may be substantially larger or smaller than seven zones. Thus information can be lost in ''contrasty'' scenes due to the limited sensitivity range of film, or the range of film can be under-utilized in ''flat'' scenes. The zone system manages this by:
The objective is to preserve and render detail the photographer feels esthetically important. Ansel Adams' famous book '' The Negative '' lays out preliminary calibration and darkroom tasks, taking test pictures of the gray card at different exposures, simulating the zones, and then developing the film. Following his directions will bring to light any miscalibration of equipment and variations of developer chemistry due to the local water supply. Once completed, the photographer will have correctly calibrated equipment and a solid understanding of the zones. Development can be ''expanded'' (underexposed and overdeveloped) or ''contracted'' (overexposed and underdeveloped). This has the effect of expanding or contracting the contrast range recorded on the film, and can be applied to scenes that have a luminosity range unequal to the dynamic range of the film. Expansion and contraction also affects the contrast of the final image, and the zone system helps the photographer to have full control over these techniques. DIGITAL Zone system could be used in digital photography in a similar way to how it is used in film photography. The important difference is that while with traditional film photography one exposes for the shadows and develops for the highlights, with digital one biases the exposure for the highlights. In this sense digital media is similar to color slide film. Although digital hardware is quickly improving, current digital sensors have less range than color film, which, in turn, has less range than monochrome film. DARKROOM Ansel Adams generally used Selenium toner when processing prints. Selenium Toning can alter the color of a print and act as a preservative, but Adams used it subtly, primarily because it can add almost a full zone to the tonal range of the final print, producing richer dark tones that still held detail. The zone system requires that every variable in photography, from exposure to darkroom production of the print, be calibrated and controlled. The print is the last link in a chain of events, no less important to the zone system than exposure and development of the film. With practice, the photographer visualizes the final print as the shutter is released. SEE ALSO EXTERNAL RESOURCES
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