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 Originally Posted by bvy
My own experience with this paper/developer combination is one of diminshing returns after the first minute. Still, I might experiment to see how the highlights are affected relative to the shadows after the first minute. ...
Adams once recommended a test for developing time. He exposed a series of step tablet images such that they centered the entire range of reproduced steps. Then he developed the images for various times until he found the time where the greatest number of steps was reproduced. That was the optimal developing time. With the papers of that era, this could be a critical test, since after a while fog and extra contrast appeared and the range decreased. With today's papers, that generally doesn't happen to any extent, and you more or less develop to completion. With Dektol, that happens in about a minute and a half; with other developers it may be different. It may also vary with the paper.
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Originally Posted by RalphLambrecht
yes, but it's a promise no filter supplier has been able to keep yet,
The Ilford set I had was very close when I tested it. At least as close as I could test with a 21 step wedge.
which midtone gray is supposedly to staying constant?
The Ilford set I tested the gray stripe on the step wedge exposure was somewhere near the geometric center of the grays visible. I did not measure the exact reflection density.
and second, is that always the right tone the exposure is judged by?
Well that is the tone you need to use to use the filter set correctly. If you try to judge exposure based on black, white or some other gray, you are not using the filter set properly as designed. I'd ignore criticism of a product what was used incorrectly.
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Originally Posted by ic-racer
If you try to judge exposure based on black, white or some other gray, you are not using the filter set properly as designed. I'd ignore criticism of a product what was used incorrectly.
It works as designed, but I think Ralph is levelling his criticism at the design.
The calibration technique from Paul Butzi in the original post describes calibrating to have consistent exposure for the highlights, which I think is what Ralph wishes the filter manufacturer had done.
So if you have a Dichroic head, you have a choice of approaches.
p.s. I use graded paper, so maybe I don't know what I'm talking about.
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0.60 logD over paper base is the ISO paper speed point. My 500H, when adjusted, seems to produce this midtone at all grades at the same exposure, for a given negative, which I believe is the meaning of a speed-matched system. This agrees with what I read in Ralph's book, which shares useful suggestions how to take this fact further, and to arrive at an equal highlight while changing grades, which may be more useful than trying to keep a rather dark midtone constant.
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More frustration. I ran the safelight test and everything came out "safe." I notice the enlarger has -2 EV attenuator plugged in. Don't know if that makes a difference.
This was done with a grade 3.5 filtration dialed in (75M+15Y) for 7 seconds (f/8). Ilford MG RC paper, 60 sec. in Ilford PQ.
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bvy,
If you'd like to send out one of the negs, I'd be happy to check to see if the problem lies in a thin neg. Send a pm... I'm sure others would be happy to make similar offer... It might be one of those things that is easy to see once its in hand.
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[QUOTE=Rafal Lukawiecki;This agrees with what I read in Ralph's book, which shares useful suggestions how to take this fact further, and to arrive at an equal highlight while changing grades, which may be more useful than trying to keep a rather dark midtone constant.[/QUOTE]
exactly.keeping a meaningful highlight density constant is what a truly matched exposure system delivers. anythin else is a nice try.
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Originally Posted by Bill Burk
It works as designed, but I think Ralph is levelling his criticism at the design.
The calibration technique from Paul Butzi in the original post describes calibrating to have consistent exposure for the highlights, which I think is what Ralph wishes the filter manufacturer had done.
So if you have a Dichroic head, you have a choice of approaches.
p.s. I use graded paper, so maybe I don't know what I'm talking about.
i could not have said it better myself.
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Originally Posted by bvy
More frustration. I ran the safelight test and everything came out "safe." I notice the enlarger has -2 EV attenuator plugged in. Don't know if that makes a difference.
This was done with a grade 3.5 filtration dialed in (75M+15Y) for 7 seconds (f/8). Ilford MG RC paper, 60 sec. in Ilford PQ.
Always hard to say for sure without seeing the actual negative, but this print/scan looks as though the negative is quite thin (ie underexposed) and also possibly underdeveloped. The darker areas (coats, dark hair etc) are all virtually empty and local contrast is weak up through the midtones.
There could be other issues (fogging of film?) and/or something going wrong in film processing. Assuming you've ruled out printing issues (safelight or other fogging, bad paper, faded filters, bad chemistry etc) it might be best to have someone look at the negatives.
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Originally Posted by Michael R 1974
...but this print/scan looks as though the negative is quite thin (ie underexposed) and also possibly underdeveloped....
Then the solution would be to find out why the film didn't get as much development as it needed.
Since you got the time right...
Check the D-76 developer temperature isn't/wasn't/couldn't have been too cold (if so, warm it up to 68-degrees F).
Or maybe it's just that your shots were in flat light (was the crowd shot on an overcast day?), in which case you would expect to print on higher grades.
I'd go back to the Ilford reference on post #3 from Michael R 1974. To simplify while things aren't going well, simplify. Use the single filter settings chart. (Adding Yellow doesn't help higher contrast grades).
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