Splitting Contrast Filters

Discussion in 'Enlarging' started by drpsilver, Mar 16, 2006.

  1. drpsilver

    drpsilver Member

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    15 Mar 2006

    I have been given quite a large selection of CP filters. Since VC papers use magenta and yellow to control contrast it seems that I could use some of these filters to "split the difference" between contrast filters, i.e. be able to print with a 2.75 contrast instead of 2 or 2.5.

    Has anyone tried to do this? Any thoughts and/or suggestions are welcome.

    Regards,
    Darwin
     
  2. david b

    david b Member

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    In the past, I've started with the 00 filter and then finished with the 5 filter. I even teach this method at the local CC. It is a very effective way to print with a crappy negative.

    But as always, a great negative leads to easy printing.
     
  3. kunihiko

    kunihiko Member

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    Yes, you can.
    You also can expose with #2.5 for half of the time, with #3 for the rest to get between them.
     
  4. hammy

    hammy Member

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    That sounds easier.
     
  5. Lee L

    Lee L Member

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    I think people may be misreading this. I think these filters are in standard color correction values, not variable contrast filters. I'd start out trying combinations equivalent to the manufacturers suggested values for each grade using a dichroic head. Those values should be in the instructions that came with the papers. You may have to add a number of filters to get those values, and yes, if you have the correct combination of values, you could go between the standard grades. You should also be able to do split grade printing with two exposures and the suggested values for grade 0 and grade 5.

    Lee

    For suggested Ilford values see: http://www.ilford.com/html/us_english/pdf/Cont.pdf

    Edit: I'd second Ed's recommendation of the Anchell book. I think I'd find it more work to shuffle a stack of CP filters through a series of tests for contrast than to do one switch per print with split filter printing, and likely harder to keep track of. But as everyone does, you'll have to find what works best for you.
     
    Last edited by a moderator: Mar 16, 2006
  6. Ed Pierce

    Ed Pierce Member

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    Check out Steve Anchell's excellent book on VC printing; it will save you a lot of time and help you to understand how VC papers work. VC filters work by varying the proportions of green light and blue light. Most filter sets use the subtractive color method (yellow subtracts blue and magenta subtracts green). However, you can also use the additive color method: green filter for low contrast and blue filter for high. One can also mix and match subtractive and additive methods and create your own filter set.
     
  7. drpsilver

    drpsilver Member

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    16 Mar 2006

    Lee hit on what my question is, and thank you for the information and suggestions. Ed, I will look for Anchell's book on VC printing. It might save me a lot of time, and paper, doing tests. If I come up with anything extrodinary I will let you know.

    Regards,
    Darwin
     
  8. Ole

    Ole Moderator Staff Member Moderator

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    I got a set of Agfa CC filters cheap, which I'm cutting to fit the filter drawer on my enlarger as the need occurs. So far I've only cut down the 20Y and the 30M, but the rest is ready when I need them.