Pyro Step Wedge

[Bill Burk]

Exposing under enlarger? I have no idea what EV to aim for, what exposure time, without running into reciprocity failure etc. I've done a few @ different exposure times and the resulting strips' higher or lower end don't always show separation. That's me reinventing the wheel. I'd probably get there. Eventually. Some precise advice would help speeding things up.

I was going to join the camp of "use the strip you got from Stouffer" but historically, Pyro was going to be considered the standard developer before D-76 became the standard... So there has to be value in having a Pyro developed master step wedge.

Hope you realized it... every step is a (a third stop ? in 31 step scales?) of exposure, you only need to adjust the time you tried... by counting the steps that show no detail... at least in the straight line section.

I always like to place the exposure so that two steps are completely clear on the negative, so that I can get good readings on the toe of the film. This is for a step wedge of the film's characteristic curve... not making a step wedge to use as a master step wedge.

So take your step wedge best effort and re-number in the opposite direction. You might not get all 31 steps... If some of your steps in the thinner densities measure exactly what you want, give them the numbers 1, 2, 3

For example step 20 might be 0.30, step 21 might be 0.20, step 22 might be 0.18 while step 23 is 0.10. So call 20 = 3, 21 = 2, "crossed out 22" and 23 = 1

[Peter De Smidt]

Follow Butzi's procedure with the Stouffer step wedge. Make your chart for your settings. Print.... I've used this system for many years with Xtol negs, PMK negs, Pyrocat negs..... There's no need to develop various step-wedge copies in different developers.

[Hans Berkhout]

Thank you all. Especialy Bill and Peter who read my question and gave it some thought, thanks your contributing your insights.

Pyro stain plays a role not only as density but also as a contrast reducing color mask, especially in the highlights ( G. Hutchings, The Book of Pyro). I am curious if Butzi's method would give me a different Y/M table when done with a pyro stained step wedge as compared to the -extremely useful-one I made years ago with a "silver only" Stouffer T3110 step wedge. Without exploring theories, pros, cons etc. I'm just going to experiment, try this and see if it will lead to something helpful for my printing of pyro stained negs on the VC paper of my choice.

[Peter De Smidt]

Since the pyro stain is proportional to density, you will get more of a contrast change in the bright areas of the print, as more of the blue light is filtered out. Consider two negatives of the same full range scene. The first negative is developed in a non-staining developer such that Zone VIII in the scene gives 1.3 above film base plus fog using the blue channel of a densitometer. The second film is developed in Pyrocat HD to the same density, again using the blue channel to measure density. With this negative the total Zone VIII density will be make up of about 30% stain and 70% silver density. If you print the negative using the same settings on the color head, there will be differences in contrast between the resulting prints, especially in the lighter areas. Does that matter, though, for the sake of printing? Suppose negative one prints best with a grade 2 settings on the color head. The best rendition of the high lights of the second negative might be better with grade 2.5 or 3. So just use that. Butzi's system gives an easy way of adding or subtracting contrast from the print while keeping near white elements in the print constant. Thus you determine exposure for the near white, using a test strip. Now make a print using your best guess filtration and the exposure just determined. Examine the print. If you need more or less contrast, consult the chart you made using Butzi's procedure, and adjust filtration to achieve the contrast you want. You can make this a complicated as you'd like, using different settings for various areas of the print....

[Doremus Scudder]

Thank you all. Especially Bill and Peter who read my question and gave it some thought, thanks your contributing your insights.

Pyro stain plays a role not only as density but also as a contrast reducing color mask, especially in the highlights ( G. Hutchings, The Book of Pyro). I am curious if Butzi's method would give me a different Y/M table when done with a pyro stained step wedge as compared to the -extremely useful-one I made years ago with a "silver only" Stouffer T3110 step wedge. Without exploring theories, pros, cons etc. I'm just going to experiment, try this and see if it will lead to something helpful for my printing of pyro stained negs on the VC paper of my choice.

Hans (and Peter and the rest of you who think that pyro stain is some kind of VC filter...)

Despite Gordon Hutchings stating this in his book, I've come to believe that it simply isn't true, and that PMK negs don't print radically differently on graded vs. VC papers.

Sure, the stain is "yellowish green," or brown, and must have a tiny bit of an absorption spectrum. The point is, is that this absorption is weak, and still passes a lot of blue. Once you start filtering, it is the color of the filter that predominates; the stain plays a minor role, if any.

Furthermore, if the stain does block blue light and pass more green, as many maintain, then using higher contrast filters should have a greater effect than with a similar contrast on a graded paper, since part of the blue is already blocked, and you're filtering out the green with the magenta filter thus filtering out two colors of light, the "stain" presumably adding some neutral density to the highlights... I've never experienced a PMK neg that printed well on graded paper needing a VC paper with markedly less contrast (often, the opposite is true).

And, calibrating a stained step wedge is going to be a bit tricky; blue channel only, blue+green, white? It might be interesting to see just how much the stain does (or doesn't) affect the transmission spectrum by making several exposures (as you would for a Zone Ruler) and then reading them through the different channels...

Take a look and Nicholas Linden's past posts dealing with this subject. He's the real authority.

Best,

Doremus

[Peter De Smidt]

Doremus, I'm fine with that. I haven't done any controlled tests to investigate this, although when I used PMK, many years ago, I did have issues with low highlight contrast. I didn't have a color densitometer back them. Perhaps the negs were simply not developed long enough. The upshot for this discussion, though, is that if Doremus is right, then there's even less reason to make a pyro step wedge.

[Cor]

Hans (and Peter and the rest of you who think that pyro stain is some kind of VC filter...)

Despite Gordon Hutchings stating this in his book, I've come to believe that it simply isn't true, and that PMK negs don't print radically differently on graded vs. VC papers.


Doremus

Doremus,

Much has been written on Pyro stain working as a VC filter and thus lowering the contrast by making the highlights well less white.. In my own experience I do see markedly different results between PyrocatHDC negatives printed on VC versus graded paper, BUT:

My mainstream VC paper (FB and RC) is Ilford, my graded paper is mostly Foma, Forte or Kentmere, and that also introduces a variable. I mainly use PyrocatHDC now for IR film: measuring for IR film (EFKE) is somewhat unpredictable, so I end up (some times) heavily overexposed highlights: IME if there is not too much stain, the stain nicely tames the highlights, but above a certain amount I cannot obtain a satisfactory print I switch to graded paper (or remove the stain).

I also use PyrocatHDc in stand development, I have not mastered that game (yet) and end up with quite a lot of stain, this negatives print better on graded paper as well.

it might very well be that when you have moderate stain the differences are minute.
Best,

Cor

[Drew Wiley]

There are so many possible variables that it gets damn difficult to forecast them, so I just go by specific test strips and experience, which makes things about a thousand times easier. But based on this experience, there is a minor discernable difference between a yellow-green PMK-ish stain effects versus a brownish pyrocat stain given an apples to apples VC paper application. This is logical. But the overall effect on contrast and highlight reproduction either way is analogous
to what happens with graded papers too. I'm not implying it would be identical, but it's not significant enough an issue to affect my workflow. When things can't
be managed normally, I resort to VC papers or masking or both (or nowadays, VC papers are largely norm, though I often use them as is they were ordinary
graded papers). Doing the research densitometry to plot the specifics is involved because you've got to read thru the stain, which is not something ordinary b&w
transmission desitometers do well. Read thru a deep blue filter like people sometimes suggest and you'll end up with so much total density that your machine can't do anything, really. So I just don't worry about it. Too much up-front prognosticating. Like I said, going about it backwards.

[Bill Burk]

The impact of stain color can be checked pretty simply: I think if you perform the Butzi calibration with Pyro-developed step wedge and Stouffer step wedge side by side on the same sheet(s) you will either see no "significant" difference, or maybe you'll see something subtle.

If there is a significant difference, or a subtle but measurable difference, then report back to us because the last time I saw a step wedge illustration there was just a slight difference in outcome...

[Hans Berkhout]

Makes sense Bill. I'll fine tune my process a bit, following the suggestions as given by you earlier. I should be able to produce a better pyro step wedge, suitable to use for the Butzi method. Which is to produce a table to turn my dichro head into a variable contrast with constant exposure light source, to be used for printing pyro negatives.