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Thread: Cold light and Pyro

  1. #1

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    Cold light and Pyro

    Hi,
    I have been reading about pyro last faew days and I think about giveing it a try. I have read that when useing pyro with variable contrast cold light head you can burn highlights with 0 contrast setting without affecting shadows and burn shadows with 5 without affecting highlights? Does it only work with cold light or does that work with dichro head also? Or is it true at all?
    Thanks

  2. #2
    Drew Wiley
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    Re: Cold light and Pyro

    Depends on the color of the cold light. I have an Aristo blue-green cold light which can
    achieve results almost indistinguishable from what I get with a dichroic colorhead. With
    the colorhead I use M or Y setting for split printing, whereas with the coldlight I project through either blue or green deep tricolor filters.

  3. #3

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    Re: Cold light and Pyro

    That is just the thing that i want to know does the green/blue light has the same effect as the magenta/yellow light.

  4. #4
    Drew Wiley
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    Re: Cold light and Pyro

    With variable-contrast paper the high contrast part of the emulsion is sensitized to blue light, while the low contrast emulsion is sensitized to green light. Magenta in a colorhead contains some blue light but blocks green, while yellow contains passes green but blocks blue. So it works just fine.

  5. #5
    ic-racer's Avatar
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    Re: Cold light and Pyro

    Quote Originally Posted by Mouse View Post
    Hi,
    I have been reading about pyro last faew days and I think about giveing it a try. I have read that when useing pyro with variable contrast cold light head you can burn highlights with 0 contrast setting without affecting shadows and burn shadows with 5 without affecting highlights? Does it only work with cold light or does that work with dichro head also? Or is it true at all?
    Thanks
    Yes, green/blue will work just like M/Y.

    I wouldn't say "without affecting xxxx" as my experience is that there is some darkening of the opposite density, depending on how much you burn.

  6. #6

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    Re: Cold light and Pyro

    So there is no advantage in useing cold instead of dichro light with pyro negatives?
    I dont know why everywhere where i have read about pyro cold light is mentioned as advantage and not dichro.

  7. #7
    ic-racer's Avatar
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    Re: Cold light and Pyro

    Quote Originally Posted by Mouse View Post
    So there is no advantage in useing cold instead of dichro light with pyro negatives?
    I dont know why everywhere where i have read about pyro cold light is mentioned as advantage and not dichro.
    Basically you are comparing additive (blue/green light sources) vs subtractive (Yellow/Magenta filters) printing on multigrade materials. The MG materials can't tell which system you are using.

    My personal preference is to use subtractive dichroic filters, because they are precision graded, repeatable, don't fade and dichroic heads quite plentiful on the used market as commercial labs switch to digital.

  8. #8
    Drew Wiley
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    Re: Cold light and Pyro

    To answer your question directly, no, there is no inherent advantage to using a cold
    light. Sometimes I go back and forth between both a cold light enlarger and the dichroic additive, with a different neg loaded in each, but developed with the same VC
    paper at the same time - did this just a few days ago. With a little practice, one can obtain identical results. Subtractive colorheads have a tiny bit of spillover of white light hypothetically affecting both emulsions, but it's apparently not enough to have any real visual effect. In other words, if I used my third category of enlargers, with true additive dichroic filtration (RGB), I wouldn't get different results on VC paper either. The brand of paper and its own idividual idiosyncrasies will have a much more
    significant effect than your choice of light source (provided a cold light contains a
    sufficient amount of both blue and green). An ordinary colorhead is a little more
    convenient to use, because you can dial the settings so quickly.

  9. #9

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    Re: Cold light and Pyro

    I thought since magenta and blue/ yelow and green are not the same wave lenght there would be some kind of visible diference.

  10. #10
    Drew Wiley
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    Re: Cold light and Pyro

    No difference because the VC paper simply does not see the red component of either the magenta or yellow. In other words, the paper is sensitized to only to the blue light in the magenta filtration, and the green in the yellow. That is also why either a deep orange or red safelight is used for such papers.

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