Originally Posted by Stephen Benskin
Adams, I believe, constructed the Zone System with the primary purpose of simplifying sensitometry in order to create a useful tool for visualizing final print values.
Originally Posted by Stephen Benskin
I would tend, therefore, to submit that over-quantifying the system is somehow defeating its purpose and returning it to the science of sensitometry, removing the simplification and, possibly, the visualization aspect as well.
As you have likely gathered from my earlier posts, I do all my Zone System calibrations visually, using no numerically quantified values at all. What I do have in the end, however, is a print of all Zones from a particular development scheme on the paper I use most often (made with camera and enlarger to take flare at both ends of the process into consideration).
This enables me to know, within a certain acceptable margin of error, what print value a given reading on my exposure meter will yield in a print on that paper (with a particular development scheme). The fact that the print values corresponding to an exposure reading/development scheme/paper choice are not quantified does not deprive them of meaning. Just the opposite for me. I find that being able to "play" my scale of greys at the time of exposure, either from a good memory of where the tones fall (similar to a musician crafting a melody), or even directly from the Zone Ruler that I have printed, relates much more directly to what I will end up with in the final print than a lot of numerical data.
The fact that paper scales vary with brand and with batch plus the fact that papers come and go (mostly go...) and are reformulated regularly, not to mention the different amounts of camera/enlarger flare, effects of print developers, etc., etc., suggests that an approach that takes the particular paper and grade and developer into account along with the entire work-flow from exposure to print is the only practical approach. Performing strict sensitometric tests on every paper I use with all my development schemes with all of those variables taken into consideration would be a daunting task, and the resulting data likely less useful to me in the field than the Zone Rulers I make from negatives exposed in my camera and printed with my enlarger.
It is in this spirit that, I believe, Adams wrote, "It is my opinion that the photographer need not devote much time to the theoretical study of print sensitometry."
And, while I agree that "the characteristics of the paper as well as the subject determines the aim contrast of the negative," I am not convinced that this needs to be sensitometrically quantified. The methodology need be no more complex than necessary to deliver desired results.
One of the things I learned very early when printing Zones is that the print Zones are nowhere near equally spaced; nor do they correspond to many of the commonly used descriptions; Zone V rarely ends up being 18% grey... That is irrelevant; if one simply accepts the unevenness of the print Zones, that there is less separation in the shadows and highlights than in the mid-tones, and that Zones fall where they fall, then suddenly one has a very powerful visualization tool in hand. One uses one's knowledge of how the system works to craft a negative that will yield desired results. Being able to do this visually is, in my opinion, the central advantage of the Zone System. The simplification and the reduced (or eliminated) need for numerical quantification coupled with the ability to develop a keen sense of what print values given exposures will yield is, for me, the "intention of the Zone System."
For me, there is a corresponding value in the print for exposure values I give a negative. They aren't linear and certainly aren't numerically quantified, but I know rather well, i.e., within the confines of the accuracy of my calibration, what print values I'm going to get. That, for me, is real meaning.
Nevertheless, printing remains an art; slight changes in print exposure move the mid-tones more than the highlights and shadows, as you mentioned above. Subtle changes in contrast, dodging and burning, bleaching, etc., etc. all contribute, often in ways often too small to quantify meaningfully, to a fine print that really sings. My goal with the Zone System is to be able to visualize well in the field and create a negative that I can use these printing tools on (as opposed to one that is too badly exposed to be able to work with easily). Again, I think this is the primary purpose of the Zone System; we need not be more accurate than that.
In closing, I guess I'm trying to say that, at least for me, placing a subject value on a particular Zone does have real meaning, but a directly visual instead of a numerical one. Also, I think the intention of the Zone System is purposefully imprecise (I wouldn't really call it vague). This allows for individual tailoring of the concepts of the system in order to achieve predictable and repeatable results within a manageable margin of error using one's own purposes, materials and procedures; and this without lots of lab work.