I’ve always found it a bit strange that the Zone System is so vague when it comes to calibration. The argument that it’s because a Zone is a range doesn't cut it for me. Just because a Zone is a range doesn’t mean a range can’t be defined and the mid point of that range determined. Adams does offer a target negative density range, and based on that people have extrapolated approximate target densities for the individual Zones.
Paper is another matter. Adams is even more vague on paper calibration. He doesn’t even touch on log exposure ranges. This makes it more difficult to extrapolate the reflection densities for the various Zones.
What I’d like to do is to present a series of models without any judgment. There is a question, however, that I’d like to propose. People talk about placing a subject value on a particular Zone, yet does this have any real meaning if there isn’t a corresponding value on the print?
All of the examples use the same paper curve. The only difference is how the print Zones are distributed on the curve. These are only a few possible models. There are probably other sources with different values.
One approach to defining the paper Zones is to use equally spaced log exposures. As the paper has approximately twice the gradient as the negative. Each 0.30 subject luminance difference would translate into approximately 0.15 log exposure difference. The first example begins with Zone VIII at 0.04 over Pb+f and each subsequent Zone is at intervals of 0.15 log exposure.
The second example uses the reflection densities as defined in Way Beyond Monochrome.
The third example uses the preferred reproduction densities in Jack Holm’s paper Exposure-Speed Relations and Tone Reproduction. His values are adjusted to include Pb+f.
The fourth example shows the placement of the Munsell Values on the paper curve. These values are psychophysically determined to appear equal spaced.
The fifth example is from the third quadrant in a tone reproduction diagram which has a subject luminance range of 2.10, slightly more than one stop flare, and a negative processed to a CI 0.58. This example isn't suggesting these are the only possible Zone placements under the stated conditions. A slight tweak in the printing exposure can easily lighten the mid-tone, placing Zone V at RD 0.74 without too much of a change in the the highlight and shadow values.
This is one of the concepts where I have a short-circuit.
Here is how I relate Zones to Print.
I took a step wedge that had been developed to "N" and contact printed it on Grade 2 paper. This related sensitometric exposure of the negative to print.
I selected a white patch on the test print and treated it as IX. Then, skipping steps to make them one stop apart, I cut chips out for the different zones down to Zone 0. (I estimated 0.4 flare when selecting representative chips for II, I and 0).
Now if I examine a scene that I could call "N" with the light meter... Once the meter is set, everywhere I point the meter corresponds to a specific print chip. If I am happy to accept that chip as what I am likely to get on a print of the scene, then I use the indicated exposure from the meter.
Bill, sounds to me like your approach to calibration is like example five.
I think you're right, example five.
But guess what I did wrong. I calibrated to a contact printed step wedge, not an enlargement as I had planned.
So enlarger flare isn't properly represented on my Master II.
I see the range between zones defined by the following as well as their midpoints, but perhaps this is not what you mean, IDK:
Originally Posted by Stephen Benskin
"It must be understood that these values (i.e. the gray scale values in figure 4-3) are merely points on a continuous scale that ranges from full black to pure white. Each single value represents a range of grays slightly darker and slightly lighter, and the individual gray values produced in a sequence like this one (again, figure 4-3) are each the midpoint of their respective zones." -AA, The Negative
I think Adams was more improvisational than systematic when it came to printing. I base this on interviews I've heard with him and the comparison of his earlier prints to his later prints of the same negatives. Also, he did make the statement that printing was a performance. I realize this doesn't negate wanting to ascribe numbers to print values, but I'm not sure why one would need to.
I'm finding that in my printing that I am happier about the prints when I can see faces that look normal in the room light where they are hung. If a face falls too dark, when I look at it from across the room, because I tried to protect the highlights, that print typically fails.
Originally Posted by artonpaper
I am finding this true regardless of the original scene, campfire just after sunset or sunny 16 doesn't seem to make that much difference, some but not a lot.
Figure 4-3 is just a group of gray patches. This is what I mean by vague. In The Print he writes, "It is my opinion that the photographer need not devote much time to the theoretical study of print sensitometry." Now, it's not necessary to understand sensitometry to make a print. That is not the point of this thread, but the characteristics of the paper as well as the subject determines the aim contrast of the negative. What does this say about a methodology that is supposed to be about controlling the materials.
Originally Posted by CPorter
On page 55 of The Negative , there is a table which has subject luminances compared to negative Zones which are compared to print Zones.
As Zone I is at 0.10 over Fb+f, the negative Zones can be extrapolated as being at intervals of one stop subject luminance differences. On the negative as well as the print, flare will need to be accounted for. The print Zones, would then be where the negative Zones fall on the print. Example 5 appears to be the most representative of this concept. Exact placement is still unknown as there isn't a RD defined to key any of the print Zones on. This would suggest Zones are not intended to appear to be a gray scale of equally perceived steps. From a sensitometric perspective, this is the approach that makes the most sense, but as the intention of the Zone System on this point remains vague, any of the examples are potentially valid.
Yes, it is just a series of gray patches, no doubt about it. Elaborate on what you mean by a Zone being a range?
But, it should not be surprising that you can go through a text like The Negative----which is meant to teach the fundamental concepts of the black and white photographic process----and find where the subject can obviously be treated in much, much, much deeper detail.
You qouted the definition yourself, "Each single value represents a range of grays slightly darker and slightly lighter..."
Originally Posted by CPorter
And I am attempting to explore the deeper detail that wasn't in the book. Actually, I'm attempting to illustrate conceptual implications and not define a specific set of reflection densities.