I don't want to give everything away just yet. I didn't say "correct one" but a "correct representation." The question concerns the interpretation of data, and specifically in this case, contrast. Creating a test wedge and plotting a film curve is just the beginning. The key is in the interpretation of the data, and a large part of that is having a good grasp of certain principles and asking the right questions.
To be more specific about the aims, the paper is a grade 2 printed on a diffusion enlarger. According to The Negative, Zone VIII density should be at 1.35 for a negative density range of 1.25. ANSI defines a grade 2 paper as having an LER of between 0.95 and 1.15 for an average of 1.05.
Mark is right in that the two curves are the same. In fact, they are drawn from the same set of data, eliminating any question about variations in development or differences in curve shape. The scene's luminance ranges are also identical in both examples, so it isn't about how different situations can be interpreted through the knowing placement of Zones.
There isn't any direct relationship between Zones and specific negative densities except for Zone I and Zone VIII and that can really only be claimed for in camera testing. Technically with exposure, you can only place one value accurately (and that point has to be tested to be known). All other points fall accordingly depending on a number of factors. It's sometimes called place and fall and the concept is used by the Zone System. This is the concept that these two examples are about. Is the way we think the system works actually reflect how it works? Are people getting what they think they are getting from testing? How good can any testing be if the data is misinterpreted?
Bill is zeroing in on the cause, but he needs to take it further and discuss the implications, and Dale is asking the right questions.
We are looking at two different things in each of the examples. There's the film curve created by exposure to a contacted step tablet, and there are points of exposure from a "scene" superimposed on top of it. This is an important distinction. What does the x-axis represent?
Last edited by Stephen Benskin; 09-07-2011 at 08:56 PM. Click to view previous post history.