First, I apologize in advance for the long post but the issues are fairly complex and I want to make sure to cover those things that I consider most relevant.
I have not read the Bond article yet but I think it fair to say that reactions to it have been pretty much predictable. Folks who believe in the superiority of pyro developers question Bond's motives and methodology and those who don't see it as proof evident that they were right all along and that all the talk about the superiority of pyro is just myth.
The original report on this article stated that Bond found PMK and D76 comparison prints to be identical in terms of sharpness and nearly so in terms of tonal range. I would like to respond to those finding, but first three comments.
1) I will try to be objective in my comments and simply state what I know to be facts and I hope that what I say will be received in that light. It is true that I personally believe pyro developers, specifically Pyrocat-HD, offer a number of advantages in my own work. However, I am not dogmatic about the issue and will willingly concede the use of pyro is not absolutely essential to the production of high quality images, and have so stated at my times in the past.
2) My approach to evaluating films and developers is based three steps: a) Learn as much as possible about the characteristics of the materials in order to have a global understanding of the issues, b) apply this information with controlled testing, and c) validate or reject the conclusion suggested by laboratory testing with work in the field. It is certainly true that the final photograph is the thing we hang our hats on, but bear in mind that any one test is valid only for the particular set of circumstances of the test so it really pays to understand the issues.
3) I have no financial interest in promoting the use of pyro. My Pyrocat-HD has been published in print and is available on various web sites, and I am not involved in the distribution commercial marketing of the product.
OK, let’s discuss tonal issues first. The report on Bond’s article notes that he found that the pyro negative and D76 negative gave almost identical tonal range and “that a little extra work would make them identical.” Sorry, but this is simply not possible with variable contrast papers. The reason is very simple. VC papers have two different coatings, one primarily sensitive to blue light, the other primarily sensitive to green. These two layers have an equal response to non stained negatives. They have a different response to stained negatives for two reasons: 1) the color of the stain affects the two layers differently, and 2) the stain is proportional, most in the areas of high density. This fact provides a kind of compensation that would be virtually impossible to duplicate with non stained negatives. You could in theory duplicate the compensation with non-staining developers for one type of lighting condition, say with subjects of very high contrast, but that compensation would give unacceptable results with subjects of less contrast.
2) About sharpness. It should come as no big surprise that Bond did note observe any difference in sharpness in his comparison prints since he is after all working with a fairly large negative and any differences in sharpness on the negative would be minimized by the enlargement ratio.
However, there is no question at all in my mind that some pyro developers give sharper negatives than D76, either straight or 1:1, assuming appropriate development. Whether this increased sharpness on the negative transfers itself to the print is another issue, but since the weakest link in the printing chain is the one that fails first I think it is smart practice to always make the sharpest negative possible, so long as other pictorial qualities (smoothness of tone, grain, etc.) are not put at risk. Assuming your objective is to make prints of maximum sharpness, of course. But you ask on what do I base this contention? The answer is a lot of specific comparison testing of D76 1:1 and Pyrocat-HD with many different films.
But first, what is sharpness. Sharpness is an impression of image clarity and is influenced by many factors, of which the most important are resolution (lines visible) and acutance (boundary definition). Resolution by itself is not a reliable method for determining image quality since as it turns out some low resolution systems appear to give results that are superior to high resolution systems, but resolution plus acutance provides reliable results. Of course an even better indicator of sharpness in optics and image systems is the modulation transfer function test, or the MTF, but this kind of testing is not available to most of us.
In practice, however, I have found that in testing both optics and film that when resolution tests are made so that the comparison negatives are of the same contrast the result is in the great majority of situations a fairly reliable indicator of actual sharpness. Persons who understand the complexity of this issue will no doubt find flaws in this admittedly imperfect system of testing but in spite of such objections I will state again that in my own work resolution when comparisons are made at the same contrast appears to be a reasonably reliable method of testing for perceived sharpness.
The bottom line is this. I can not absolutely prove to you that pyro negatives are sharper than D76 1:1 negatives. What I can do, however, is prove that Pyrocat-HD (and I believe this would also be true for both PMK and WD2D+) gives better resolution, on the order of 10-20 lpm, than D76 1:1. If you don’t believe me test it yourself by doing this.
1. First, determine what time of development is need to develop the same effective printing contrast with the two comparison developers. You can do this with either a step tablet or with a densitometer. However, if you use a densitometer make sure that you take into consideration the actual difference between what you read and effective printing density.
2. Next, set up a standard resolution chart and with your camera on a tripod make a series of exposures of the chart, at least four for each developer. You could do this with virtually any camera system. I use a high quality medium format camera for my own testing because of the quality of the optical system but you could also use a large format camera provided that the lens is of sufficiently high quality. For your tests use a film capable of resolving over 100 lpm. In my case I use a 6X9 camera and make eight identical exposures on 120 film at a lens aperture of f/11, focusing on the ground glass.
3. Develop the film for the times previously determined to give the same effective printing contrast. In my own tests I cut the 120 film into two parts, developing one in D76 1:1, the other in Pyrocat-HD. Be sure to use the same method of agitation with both developers.
4. When the films are dry examine them at about 40X magnification and calculate the resolving power of the D76 and pyro negative. Since you used the same lens aperture and same roll of film for all of the tests you can be reasonably certain that any difference in resolution observed results from the developer, not the lens or camera system.
5. If you have access to a very high resolution scanner you could validate your observations by scanning the chart at maximum ppi, enlarging the results, and outputting to a printer. I calculate that this step would require a scanner of about 8000 – 12000 ppi. I tried this with my Epson 4870 but this scanner will not resolve as many lpm as are on the negative.
In conclusion, I recognize the limitations of this type of testing as they have already been pointed out to me by someone with extensive knowledge in the field. However, I am personally satisfied that the results do provide a reasonably accurate indicator of negative sharpness. The question of final image sharpness is of course another matter and I do not intend to address it here. It is sufficient for me at this point to know that Pyrocat-HD gives me sharper negatives than D76 1:1.
I welcome and expect reasoned comments on both the methodology and conclusions as herein presented.
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, is that I'd probably worry more about getting the solution on my skin repeatedly than the occasional dust, and the Merck warnings are probably only relevant if you work with it in vats. This being said, from the skin straight to your blood stream will have a different effect than ingesting it where it can be partially broken down first. We look at photographers from that era; Strand and Adams lasted a good, long, time, Weston succumbed to Parkinson's, which may be genetic, or may be because of sensitivity to the chemistry he used. Unless someone wishes to help fill out the paperwork so that I can spill pyro solutions on grad students and observe the results, we'll have to go with "it's probably not too bad in the quantities you're using".
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