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  1. #1
    bvy
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    Dichroic Calibration - Worth It?

    I've been making more prints lately trying to get better contrast -- i.e. the darkest blacks possible without bringing down the highlights. I'm not interested in dodging and burning at this point. The literature suggests that a grade 2 or 3 filter will cover most printing needs, but my results with these always seem to be flat. As such, I find myself using the grade 5 filter more often than not. I thought grade 5 was for slightly more advanced techniques -- like spilt-grade printing -- and not really to be used by itself. Even so, I'm not completely satisfied with my grade 5 prints.

    So I've done some more reading and came across some threads and this link about calibrating your enlarger's color head for variable contrast printing:
    http://www.butzi.net/articles/vcce.htm

    It sounds promising -- I expose for the highlights, and then make adjustments to increase the contrast (blacks) while holding the highlights constant (casually speaking). I have an Omega C760 with dichroic head, but I don't have a light meter or step wedge transparency to run the tests. Before I go down this path and buy "more stuff," I'm wondering if anyone can speak to this process. Does it live up to its promise? Is it worth the effort? I understand the concept and I like the idea, but I want to hear that it holds up in practice and isn't just another academic exercise.

    Thanks.

    (I'm using the Ilford multigrade filters with Ilford MGIV RC paper. I'm using the white light setting of my dichroic enlarger and holding the filters under the lens. My paper developer is Ilford PQ 1:9, 60 seconds.)

  2. #2
    chriscrawfordphoto's Avatar
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    It would be easier for you to produce negatives that print well on grade 2. Develop them longer and you won't need to use grade 5.
    Chris Crawford
    Fine Art Photography of Indiana and other places no one else photographs.

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    Probably only worth doing if you want to figure out exactly which settings to use on your colour head to precisely duplicate the effect of each of your Ilford filters. Not sure I'd bother with that unless your process for exposing and developing negatives was already calibrated to the Ilford filters. Based on the first part of your post, that does not appear to be the case. So if you want to switch from the Ilford filters to using your colour head (yellow and magenta), you can download Ilford's recommended magenta and yellow settings, use them as approximations and go from there.

    http://www.ilfordphoto.com/Webfiles/...8932591755.pdf


    The problem of insufficient contrast is another matter, and will not be solved by moving to using the colour head. If you find yourself always needing high contrast filters, first do some darkroom tests for things like safelight fog or enlarger light leaks, make sure your filters aren't faded, etc. If everything checks out and your paper and developer are fresh, then you're simply not getting enough contrast in your negatives. Try increasing negative development time. Monitor temperatures. Make sure you are agitating enough etc.

    If you increase the contrast in your negatives you won't need to resort to using high contrast printing filters all the time.
    Last edited by Michael R 1974; 12-27-2012 at 01:03 PM. Click to view previous post history. Reason: Typo

  4. #4
    cliveh's Avatar
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    Quote Originally Posted by chriscrawfordphoto View Post
    It would be easier for you to produce negatives that print well on grade 2. Develop them longer and you won't need to use grade 5.
    I would agree with this post and go further by saying that you should (where possible) produce negatives that require no filtration, given your film development procedure and enlarger type/set up.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

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    Ilford filters give the full range of contrasts without the need to calibrate a dichroic head. Based on what you have said dichroic calibration is not the answer to your problem. Do what Chris Crawford has suggested initially.

    If that doesn't solve your problem then it is even possible that your personal film speed is wrong i.e. it is possible to develop longer and still not have good negs that will give a fine print on grades 2-3. Your exposure based on a correct film speed has to be correct.

    However first things first. Develop for longer and see what does does

    pentaxuser

  6. #6
    MattKing's Avatar
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    The suggestions above are good. Here are a couple of other things to think about:

    1) it would be prudent to check your enlarger's light source. If, for example, the bulb is wrong or there is some cyan filtration that is not moving out of the way when you use the white light setting, there may be too much green light hitting the paper and therefore reducing the contrast;
    2) light sources with dichroic filters are really nice to use, so if you have one that is working well, you may appreciate the flexibility it offers. You don't really need to calibrate the source, unless you are trying to match previous work. What you need to do is use the Ilford link above to get a reasonable idea of the range, and then become familiar with how it performs, so you can use it reliably in the future. The numbers themselves don't matter, it is the correlation between the settings and how you perceive the results;
    3) it is possible that your desire for high contrast relates mostly to how you see the prints - you may prefer something like the "soot and chalk" look as compared to something with fine tonal gradation. If that is the case, you will need both contrastier negatives and high contrast enlargement filters/settings. I looked at the one enlargement you posted in the APUG gallery and its contrast looks fairly normal. Does it look low in contrast to you?
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  7. #7
    bvy
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    Thanks everyone. Develop longer as in push a stop? For this session, the negative is Tri-X 400 from my Olympus XA4, developed in D76 1:1 for 9:45. Fresh everything.

    I also use the dialed in filtration, and I have the equivalents from the insert that ships with the paper. (I'm using the Kodak line.) I did some tests a while back and found that the results from the physical filters versus the dialed in filtrations weren't always the same. Maybe my filters are faded (?); anyway, it was a casual test.

    Here are some examples. I like the shadow detail in the top print (grade 2 dialed in) but the blacks aren't very black. The bottom print has blacker blacks and good contrast but the shadow detail is gone.

    Click image for larger version. 

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  8. #8
    cliveh's Avatar
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    Quote Originally Posted by bvy View Post
    Thanks everyone. Develop longer as in push a stop? For this session, the negative is Tri-X 400 from my Olympus XA4, developed in D76 1:1 for 9:45. Fresh everything.Click image for larger version. 

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    Try 12.5 minutes.

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  9. #9
    Rafal Lukawiecki's Avatar
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    Quote Originally Posted by Michael R 1974 View Post
    If you find yourself always needing high contrast filters, first do some darkroom tests for things like safelight fog or enlarger light leaks, make sure your filters aren't faded, etc. If everything checks out and your paper and developer are fresh, then you're simply not getting enough contrast in your negatives. Try increasing negative development time. Monitor temperatures. Make sure you are agitating enough etc.
    I second Michael's recommendation to check your safelight. Please consider using the Kodak test, and not a "coin test" or its variants. It will only take 10 minutes.

    Unsafe safelight that does not fog paper will reduce contrast and it will force you to use excessively hard contrast filtration, in addition to causing other issues with print-to-print consistency. Second to that would be checking your enlarger for significant light leaks.

    I would say that 4 our 5 darkrooms which I have visited had unsafe safelights. All the other suggestions, which you got, are pretty good too.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

  10. #10
    cliveh's Avatar
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    Quote Originally Posted by Rafal Lukawiecki View Post
    I second Michael's recommendation to check your safelight. Please consider using the Kodak test, and not a "coin test" or its variants. It will only take 10 minutes.

    Unsafe safelight that does not fog paper will reduce contrast and it will force you to use excessively hard contrast filtration, in addition to causing other issues with print-to-print consistency. Second to that would be checking your enlarger for significant light leaks.

    I would say that 4 our 5 darkrooms which I have visited had unsafe safelights. All the other suggestions, which you got, are pretty good too.
    If you don't have a densitometer, what's wrong with the coin test?

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

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