Separation Negatives and Masking

Discussion in 'Color: Film, Paper, and Chemistry' started by ciocc, Feb 13, 2006.

  1. ciocc

    ciocc Member

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    Hello -

    I need to make separation negatives from a 4x5 color transparency with my enlarger. I took the transparency to a pro lab, and asked them to measure the density range. I was given three numbers: r=1.84, g=1.99 and b=1.77. The exposure scale of the "paper" the negatives will be printed on is 1.65. Does this mean I need to make three masks, one for each negative so that each one fits the exposure scale of the paper? I've never done this before, but this is what seems to make sense. This is for a color assembly printing process, but if I were doing RA-4, which of the three density ranges would be the mask be made for?

    Thanks in advance.

    Eric.
     
  2. sanking

    sanking Member

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    A couple of books on making color separations for color assembly processes.

    Pilkington, W. J. Color Separation Negatives. London, 1952.

    Miles, Southworth. Color Separation Techniques. New York: Graphic Arts Publications, 1979.

    See also, Mindy Beede, Dye Transfer Made Easy, Amphoto Books, 1981, for some practical ways of going about this without a lot of expensive sensitometry equipment.

    And Kodak Q-7A booklet for the graphic arts. Maybe out of print but you can perhaps find a used copy somewhere.

    Sandy
     
  3. Claire Senft

    Claire Senft Member

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    I believe that making a single mask by white light that will reduce all three colors below 1.65 will suffice. You may also wish to make a highlight mask.

    I wonder if you would not be well advised to have a lab make you an internegative.

    Do you have a film punch?
     
  4. df cardwell

    df cardwell Subscriber

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    san cristobal

    what are you setting out to do with a color sep neg ???

    d
     
  5. ciocc

    ciocc Member

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    Sandy: One of the books you list is in a bibliography I was perusing. I'll probably get that one. I have Spencer's book, which talks about masking, but it's a bit fuzzy for me.

    Claire: If a lab can do all this for me, I will gladly pay them to do it. I'll pick up the phone and start calling around. I have access to a registration punch if I need one.

    Eric.
     
  6. Donald Miller

    Donald Miller Member

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    I don't understand what you are attempting to do. Is it just to reduce the density range of your color negative?
     
  7. ciocc

    ciocc Member

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    I'm setting out to make a color print using an obsolete assembly process.

    Eric.
     
  8. ciocc

    ciocc Member

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    I'm a moron when it comes to this stuff. I need to make separation negatives from a transparency. I read that transparencies have a long density range.
    The book said that reducing the development time of the separation negatives will reduce the saturation of the colors. Supposedly a mask will lower the density range of the transparency, but the color saturation won't be reduced. I don't understand all this stuff, but I'm going to read one of the books that Sandy recommened. As I posted earlier, maybe a lab can do it all for me.

    Eric.
     
  9. Donald Miller

    Donald Miller Member

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    I used to mask transparencies for printing on Cibachrome...I used black and white negative film to produce a low density and unsharp mask that was then sandwiched with the transparency and printed together. The effect of the negative is to reduce the density range of the positive (transparency).

    The other way of doing this used to be to produce an internegative of the color transparency and this also had the desired effect.

    The mask is something that should be fairly easy to do...it is not rocket science...the internegative requires a lab, in my opinion.
     
  10. boyooso

    boyooso Member

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    What type of print will you be making from your separation negatives?

    a chromagenic print?

    Corey
     
  11. sanking

    sanking Member

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    You don't need to make a mask. You just need to learn to balance the exposures frm your transparency to B&W film through the Red, Green and Blue filters to give an identical Dmin, and then develop the negatives to the same contrast. This will take a bit of time to balance, but to make color prints with carbon you must do so.

    My immediate advice would be to make a transparency using your favorite film and put a large gray scale in the picture, or put it close to the camera. this will be of immeasurable help later when you try to match density and contrast. Once you get this balanced, exposure and develoment will be almost identical for other trnasparencies.

    Sandy



     
  12. ciocc

    ciocc Member

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    One of my books talks about masking as you describe. It sounds fairly easy. My problem with all of this is that I'm following instructions in books, but I have no clue why it needs to be done, why it works, etc. It's unpleasant not having an understanding why you do what the book tells you to do. I'm learning as I go along. Fortunately it all works as advertised.
     
  13. ciocc

    ciocc Member

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    To be honest, I'm confused. What you say is what I originally understood I needed to do. One of the books started talking about loosing color saturation, and it said a mask was necessary. You've always given me good advice, so I'll do as you recommend. I have a transparency that my heart is set on printing. I was hoping that I can use it, rather than make another one.

    Eric.
     
  14. sanking

    sanking Member

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    Eric,

    Have you considered making some in-camera separations? These are relartively easy to do, and if you choose the right subject (one that does not move for about a minute or so while you make the three exposures) the results can be outstanding. Most of the better three-color carbons I have made were made witih in-camera separations. You can use virtually any panchromatic film for this but those that have very straight line curves work best as they avoid contrast cross-overs.

    Sandy


     
  15. Donald Miller

    Donald Miller Member

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    The mask that I used works because it compresses the density of the original transparency. It does this because it has no color in and of itself and it is a negative of the positive (the transparency).

    Chris Burkett http://www.christopherburkett.com/ who turns out some of the finest traditional color prints today uses masking of his transparencies in his printing process. To my knowledge, he does not do color separations.

    If you will access his darkroom page from this page, you will see that he clearly masks his transparencies. http://www.christopherburkett.com/pages/home.html

    I have had color separations done of color transparency but it was when I had a printer do a graphic printing of a poster years ago. In that case, the four color printing process required separations since it was a graphic output as opposed to a photographic output.

    The only other time that I have heard of anyone doing color separations was in regard to the dye transfer process. While JandC offers the matrix film for this process, I am not sure of a source for the dyes. I do know that Kodak discontinued them years ago.

    I guess a great deal depends on what you are wanting the output to be.
     
  16. Photo Engineer

    Photo Engineer Subscriber

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    We need more information on the printing process.

    Unless you are doing something like dye transfer (magazine color prints involve a dye transfer process), there is usually no need for separations or masking. Color negatives have the mask built in.

    PE
     
  17. sanking

    sanking Member

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    The printing process is three color carbon. And we don't need masking in making the separations for three-color carbon, rather we try to balance the density and contrast of the B&W separations through Red, Green and Blue filters.

    Sandy




     
  18. ciocc

    ciocc Member

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    Yes. In fact, I'm thinking about photographing a colorful mural that's right next door to my house. Since I'm learning this process, I might as well make things easier on myself.

    Eric.
     
  19. Photo Engineer

    Photo Engineer Subscriber

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    Sandy, I agree with your comment. The statement in another post said that he was using transparency which had a long tone scale.

    AAMOF, transparencies from color have a very short tone scale, that is why a contrast mask must sometimes be made, and the color correction is poor so that is why color masks have to be made.

    In this particular case, the type of dye used in the three color carbon will introduce additional imperfections in color rendition.

    So, it may be, depending on the ultimate quality demanded of a given process that either no mask is needed or a full set of masks is needed. The carbon and bromoil color prints I have seen look beautiful without the masks, but then again, they probably were made from in-camera separations, being from the 20s and 30s. Making them from color transparencies may not yield as good a result.

    Anyhow, I would defer to your judgement, never having made a color carbon or bromoil myself. I do know that under the right conditions dye transfer can give superb results without any masking.

    PE