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  1. #1

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    Advise needed: Looking for an additive filtration(Blue & Green) enlarger

    Hi folks,

    I am looking for a way to do additive filtration enlarging. I have been using this Aristo VCL head with Blue and Green twin tubes at the local lab, and I am loving it.

    So, I started looking for an enlarger that will allow me to do Blue and Green split grade enlarging. And I feel like I am running in circles. Aristo doesn't seem to make VCL anymore, nor can I find any on-sale on ebay.

    I did run across the Philip PSC enlargers, like the PSC 130 or the PSC 2000.

    Are there any other choice? I think I would prefer not to do drop in filters, which as far as I can tell, won't give me an even spread of light.

    Please help. after using the VCL head, I don't really want to go back to using the subtractive filtration system. I love the fine control I can get with the additive split grade system.

    Thank you in advance.

  2. #2
    jeroldharter's Avatar
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    Just get a dichroic light source and use yellow and magenta instead of green and blue. For B&W printing it does not make much difference.

    If you really like the cold light, you could buy a standard, used cold light and add below the lens filters (which will be yellow and magenta).
    Jerold Harter MD

  3. #3

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    That would be subtractive, no?

    I found that tends to clump up the blacks, while with Green & Blue, I can hit just 1 of the two emulsion layers on the paper at a time. So far, it has allowed me to do some very fine tuning of the different tones through out the shot.

    I don't think you can do that with yellow and magenta. Right?

    Da.

  4. #4
    jeroldharter's Avatar
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    Quote Originally Posted by mouren View Post
    That would be subtractive, no?

    I found that tends to clump up the blacks, while with Green & Blue, I can hit just 1 of the two emulsion layers on the paper at a time. So far, it has allowed me to do some very fine tuning of the different tones through out the shot.

    I don't think you can do that with yellow and magenta. Right?

    Da.
    Yes, that is subtractive printing in color. But, no that is not right that yellow and magenta clump up blacks.

    Sounds like you might be split printing - a blue exposure for shadows and a green exposure for highlights. You can do the same with a dichroic light source by substituting magenta and yellow respectively. It works exactly the same way. Or you can combine varying mixtures of yellow and magenta to yield a specific contrast grade - just like you can do with blue and green on an Aristo VCL light source.
    Jerold Harter MD

  5. #5
    MattKing's Avatar
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    Quote Originally Posted by mouren View Post
    That would be subtractive, no?

    I found that tends to clump up the blacks, while with Green & Blue, I can hit just 1 of the two emulsion layers on the paper at a time. So far, it has allowed me to do some very fine tuning of the different tones through out the shot.

    I don't think you can do that with yellow and magenta. Right?

    Da.
    The Yellow filter is used to subtract out Blue, and leave Yellow. Yellow light = Red + Green and the paper isn't sensitive to Red, so in essence the Yellow exposure just affects the Green layer.

    The Magenta filter is used to subtract out Green, and leave Magenta. Magenta light = Red + Blue and the paper isn't sensitive to Red, so in essence the Magenta exposure just affects the Blue layer.

    IIRC you get better (purer?) results doing it this way, as compared to using Green and Blue filters or light sources.
    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

  6. #6

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    The Ilford Multigrade 500 and 600 heads use green and blue filtration. They crop up frequently second hand for lower and lower prices. However, I also think that (as Ilford made these) they do equate to the same result with multigrade papers whichever filter type is used.

  7. #7

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    Or look for a Zone vi enlarger
    "There are a great many things I am in doubt about at the moment, and I should consider myself favoured if you would kindly enlighten me. Signed, Doubtful, off to Canada." (BJP 1914).

    Regards
    Bill

  8. #8
    Nicholas Lindan's Avatar
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    Green and blue subtractive filtration is identical to yellow and magenta subtractive filtration. Making pure yellow and pure magenta exposures separately is identical, as far as the paper is concerned, to making pure green and pure blue exposures. Both emulsions in VC paper are sensitive to blue light, one is also sensitive to green light. Modern VC papers have three emulsions where the third is sensitive to blue and slightly sensitive to green.

    What you are describing is green and blue additive light sources. The Ilford 500 systems work this way: two lamps with fixed filters where the exposure of the two lamps is timed separately. VC cold light systems use two tubes with different phosphors.

    There were some color enlargers from the 70's that used additive RGB color.

    There is no theoretical advantage to one system over the other: you can get identical prints out of either.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  9. #9
    ic-racer's Avatar
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    Quote Originally Posted by mouren View Post
    Are there any other choice? I think I would prefer not to do drop in filters, which as far as I can tell, won't give me an even spread of light.
    ??

  10. #10

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    Thank you to everybody who responded, definitely set me straight.

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