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  1. #1

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    Calibrating dichroic head for ILford Multigrade

    Firstly, please don't laugh because I'm dragging out equipment made in 1972 and daring to make it work.I have this 1972 Beseler PM2 Color Analyzer in pristine cosmetic condition. Possibly it would need new filter capacitors in the power supply, but for now, I want to perform an experiment. I have a Beseler 67C with colorhead and I want to see if I can get the analyzer to help me jive my dichroic filtration to duplicate the filtration that my Ilford Multigrade filter set would give. If that makes sense.
    I've researched this on the old APUG threads and someone included an Ilford publication discussing this matter. In that publication there were perhaps 3 systems--a Durst, a Kodak, and Meopta, I believe. From what I could gather, my Beseler was listed under the Kodak classification.
    I may be missing something here. But I'd still like to play with this analyzer and see if it will match the dichroic to the gelatin filters. Thanks.

  2. #2

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    I have based my calibration on this article:

    http://www.butzi.net/articles/vcce.htm

    I use a two-tube VC head, Aristo VCL4500, but the principle is the same.

    It might seem like a lot of work, but it's not bad. One session in the darkroom with a Stouffer Transmission Step Wedge and a bit of arithmetic with a spreadsheet and you're done.

  3. #3

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    Thank you. I don't have a 31 step Stouffers, but I do have about a 20 step one. But while I've got you on the line, how compatible is a set of old Polycontrast filters to a set of Ilfords? Anybody know?

  4. #4

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    1972 isn't old for darkroom equipment.

  5. #5

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    It's getting on in years for electronic equipment though. I really ought to find a repair manual and go through and check voltages. Caps get leaky and resistors change value. I haven't opened it up for a look-see to find out what's in it. It's still a virgin. Nobody's ever opened it up and tinkered with it.

  6. #6

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    Quote Originally Posted by Chan Tran View Post
    1972 isn't old for darkroom equipment.
    i was just going to say -- 1972, he's using the new stuff. I think my focomat 1c was made in the 60s, or maybe earlier. That stuff never wears out.

  7. #7
    ic-racer's Avatar
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    Quote Originally Posted by HTF III View Post
    Firstly, please don't laugh because I'm dragging out equipment made in 1972 and daring to make it work.I have this 1972 Beseler PM2 Color Analyzer in pristine cosmetic condition. Possibly it would need new filter capacitors in the power supply, but for now, I want to perform an experiment. I have a Beseler 67C with colorhead and I want to see if I can get the analyzer to help me jive my dichroic filtration to duplicate the filtration that my Ilford Multigrade filter set would give. If that makes sense.
    I've researched this on the old APUG threads and someone included an Ilford publication discussing this matter. In that publication there were perhaps 3 systems--a Durst, a Kodak, and Meopta, I believe. From what I could gather, my Beseler was listed under the Kodak classification.
    I may be missing something here. But I'd still like to play with this analyzer and see if it will match the dichroic to the gelatin filters. Thanks.
    I have done that experiment, but the color meter readings I got through the high grade Ilford Filters (4 and above) were not accurate. I suspect that is due to a sharp cutoff in the spectrum on those filters. As you have probably noticed, the Ilford #5 filter is not the same color as the magenta filter in a dichroic head, though they should give the same contrast grade. Problem is your PM2 probably won't read those high-contrast 'non-magenta' filters correctly. Try it and see.

  8. #8

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    All the information is on our website :

    Simon ILFORD Photo / HARMAN technology Limited

  9. #9

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    [QUOTE=Simon R Galley;1488302]All the information is on our website :

    Simon ILFORD Photo / HARMAN technology Limited[/QUOTE
    I had researched this on APUG before taking out this new thread and found this link (below). But I was unclear. So, Simon Galley, since I am using a Beseler 67 Dichro, does this mean I pick out my listing under the Kodak category? And if so, a complaint about my enlarger is that it is too bright. When printing color, I have to throw a lot of cyan into it and run up my magenta and yellow to keep proportions, to lengthen exposure time. Assuming I've interpreted the Ilford information correctly, will this work here too? I wonder how accurate these charts are from one model of a certain make to another.
    I have a couple sets of Multigrade filters, but no matter how carefully you handle them, sooner or later they become something you don't feel comfortable holding under the lens. And a last question while I've got you on the line: I've got a set of Kodak Polycontrast filters in the little plastic yellow storage box. Are they compatible at all with Multigrade? Thank you. Here's the link from an old APUG thread.:
    http://www.dedokawinkel.nl/mg4.pdf

  10. #10
    Muihlinn's Avatar
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    All color heads, even same model of same brand, are different, and you don't need to match the filtration against a set of filters, you need to match the filtration against the paper's ISO R.

    Start with the recommended filtration for all grades and using a stouffer determine the ISO R, then you will know if you need more or less for each grade. The idea is matching against a evenly distributed contrast range, not against what comes up from the filters.

    Talking from memory, on 21 steps tablets each step is half stop. There are 30 R units per stop so ISO R will be dmax-dmin x 15 (numbers on tablet). Is not super-precise but it will put you on track quickly and you can refine later. The key is having a pure white in the strip. If you have a densitometer choose 0,04logD for dmin, proof for dmax and use 90% of it as dmax. I should say again that I'm talking from memory, so check for the right figures on available literature.
    Last edited by Muihlinn; 04-19-2013 at 10:38 AM. Click to view previous post history. Reason: 'cos I can
    Luis Miguel Castañeda Navas
    http://imaginarymagnitude.net/

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