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Digital Zone System - Gray Levels Equivalents - Target Characterizer - Relevant Thoughts


by Richard Chang


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Teaching digital photography has been at times, difficult. Perhaps the biggest impediment to success is the lack of terminology that would bridge the differences between traditional and digital photography. I believe I've found a way to use the Zone System we're familiar with (some more so than others, but don't give up right away if you don't consider yourself an expert) to take the mystery out of digital and speed the learning of the new technology.

Now that Calumet Digital Solutions has taken over the sales of MegaVision products worldwide I've been charged, along with my East Coast counterparts, Tim Palmer and Sean McCarthy, with the task of developing training and education materials for customers who purchase our products and for the non-customers who attend the workshop series we'll be hosting. It is my belief that any digital product you choose should be able to be able to make images at the highest level it's capable of with a minimum of stress and as flat as possible a learning curve. 

Consider if you will, the last film camera you purchased. If you are the typical professional photographer, it was not your first camera. The learning curve on your last camera purchase probably consisted of camera controls and perhaps a few new film emulsions. Chances are, you got excellent results almost immediately. This is certainly not the standard digital experience. Why? 

If we consider the numerology of digital photography we usually end up with a numbering system that has 256 possibilities, called gray levels. I sometimes wondered if the digital folks who developed and instituted this system could come up with a progression even more obscure than the f-stop progression. Actually, computers count very effectively in multiples of 2 which when factored, becomes, 4, 8, 16, 32, 64, 128, 256, 512, etc. If you've been around computers any length of time, these numbers are familiar as bus speeds, ram caches and ram chipsets. The 256 gray levels system divides the gray scale into 256 sections with black at 0 and white at 256. Why do I consider the 256 scale inferior? What value in a 256 scale would you suppose is an appropriate value for caucasion skin tone in open shade? If you don't know you are not alone.

I believe the understanding of 10 different tones is far more approachable than 256. Most photographers have heard of Ansel Adams and his Zone System. Ansel's photographs have emoted all viewers with their impeccable transition of tone. His ability to predict his final image with all its splendor was based on understanding his equipment's "Show Info" (Ansel used a 1 degree spotmeter), thereby enabling him to modify the exposure and development of his media, which resulted in producing exactly what he envisioned when he tripped the shutter.

It is my suspicion that photography needs a method of aligning digital capture with traditional implementation and the zone system may very well be that link. The Zone System is easier within the digital workflow. The testing difficulties that drove most would-be practictioners away from the Zone System are non-existent with the computer moving the densities. And while I do not recommend depending on the monitor for direct visual interpretation of your work, it is valuable for gauging the effects of changes by the photographer, especially when one can toggle "before" and "after" with an Edit>Undo command. One can implement a plus-1 "developement" for example and if it's not perfect it can be undone and another, different development can be tried. You can see the effect and save it, if you like it. In addition, that development can be applied in any fashion anywhere from highlight-to-shadow.

Where the 256 levels system is difficult is in the prediction of proper placement of reflectances. Many commercial photographers use Polaroid to "proof" their images before shooting film. While commercial photographers use Polaroid for the proofing of images, the fine art shooter has traditionally utilized the careful metering of scene contrast to make appropriate decisions on exposure and development. The counting of the number of stops in the scene contrast as compared to the number of stops the film will hold has allowed the careful shooter to fit (expand or compress) the scene on his film of choice. The digital process does not yet have a "Polaroid" for the proofing of images. Just like film based photography, the successful digital image must place the correct number of tones on the target. In addition, the transition of tone must communicate the emotional intent of the photographer or client. My biggest difficulty in teaching the digital process has been the communication of information that would allow verification of the photographer's pre-visualized intent. My first efforts, with Sony's Seps 1000 video capture, in 1992 were centered around the gray level scale, 0-256. The 256 level scale surfaced again in 1994 when I started shooting the Leaf DCB. In fact, almost all capture devices use the 256 level measurement standard.

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