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  1. #1
    holmburgers's Avatar
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    Printing RA-4 with "three-color" filters - 3 separate exposures, 1 sheet of paper

    Hey,

    So I've stumbled across something that I'm curious about. I picked up quite a few wratten filters and whilst reading about them in the booklet "Kodak Filters for Scientific and Technical Uses" came across this interesting prospect.

    Straight from the book....

    "Printing with "Three-Color" Filters. Color print materials are sometimes printed with separate red-, green- and blue-light exposures rather than with filtered white light. The exposure through each filter is varied independently to control the color balance of the print. One such three-filter combination is KODAK WRATTEN Filters No. 25 (red), No. 99 (green), and No. 98 (blue). These filters, whose spectrophotometric curves are displayed below, are suitable for printing Kodak color negative products on Kodak color print materials (both film and paper)."

    Now, doesn't this seem enticing? It seems to me like this would give you the ability to control color balance more akin to dye-transfer or tri-color carbon. That is, having complete control over the exposure of each individual color. Or, does this really provide an advantage?

    Is anybody out there doing this? What do you think, intrigued enough to give it a shot?

    Look forward to your comments,

    Cheers!
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  2. #2
    Photo Engineer's Avatar
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    I believe that there is someone doing this here. There was a thread on this a while back. We used 98,99 and 70 though as the 25 was rather broad.

    PE

    When all is said and done, more is said than done. (Bob Bacon, emulsion engineer)

  3. #3
    holmburgers's Avatar
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    Interesting... it does seem like a 25 wouldn't be very sharp. I'll see if I can't find this other thread; a link would be most appreciated!

    They suggest 29 red, 61 green and 47B blue for Kodachrome/Ektachrome printed in the same manner. These of course are the classic color-separation filters for seps from real life. Why wouldn't the same be suitable for negative films? My guess would be that it is the orange mask, or maybe I'm missing something else.
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    In several of the Kodak Endura spec sheets, they recommend using 25, 99, and 47B filters for tricolor exposures. They also give you ratios for starting times as well as what to change if color balance is off.

  5. #5
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    I don't have the thread reference, sorry. I have done a little of this type of printing and it is a real pain. You tend to get unsharp images due to enlarger shake or registration problems, and color balance is difficult to judge.

    OTOH, you get brighter colors as there is less crosstalk. I have some examples around here somewhere and the difference is striking.

    PE

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    Just to clarify--- are we talking printing positives on ra-4 or negatives? This would be interesting to try with b/w separation negs, but methinks getting the registration right would be a project in itself.

  7. #7
    holmburgers's Avatar
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    Am I correct in my assumption that this makes printing on RA-4 more like DT/carbro? At least in terms of control of color values.

    If you say the difference is striking, then that's good enough for me. Yes, registration would be a real pain I bet.

    Come to think of it... you could print black & white separation negatives in this manner as well, couldn't you!? And... that means that ultimately you could mix the color channels and achieve effects akin to EIR, etc. http://www.apug.org/forums/forum40/8...-eir-film.html

    This whole notion is new to me, that you could do multiple exposures on one sheet; hence the excitement.

    Thanks for the responses!

    edit: yeah, good point jpberger on registering the sep negs being incredibly difficult....
    If you are the big tree, we are the small axe

  8. #8
    AgX
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    There were special enlargers/colour heads (Agfa, Philips) employing this concept.

  9. #9
    Greg Davis's Avatar
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    JP, This is an additive printing process from a color negative onto RA-4 paper.
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  10. #10
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    Actually, it is all of the above. You can do any of the things mentioned above as long as you balance the exposures properly and as long as you can register the 3 separations in the final image.

    I used a vacuum register board and a punch for some work with negatives and prints, with others I just used an ordinary easel and the Kodak tri-color print wheel which they used to make for mounting below the lens. It minimized any motion you might have and was therefore easy to retain registration.

    What it does in separate the 3 color images more than white light exposure does and therefore yellows, magentas, and reds are more vivid. Cyan and green are sometimes improved, but the RA4 paper and most films have such a far red that it does not cause a significant improvement. Using a WR70 did more than a 29 in this regard.

    PE

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