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  1. #31
    Ektagraphic's Avatar
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    So it is not possible to take a black and white negative, place it in the enlarger, place a piece of paper, expose the paper with one color filter and repeat this process rexposing the paper with however many filters are needed?
    Helping to save analog photography one exposure at a time

  2. #32
    Photo Engineer's Avatar
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    Quote Originally Posted by Ektagraphic View Post
    So it is not possible to take a black and white negative, place it in the enlarger, place a piece of paper, expose the paper with one color filter and repeat this process rexposing the paper with however many filters are needed?
    Of course it is, but you need 3 color negatives as stated above!

    PE

  3. #33
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    Quote Originally Posted by Photo Engineer View Post
    Of course it is, but you need 3 color negatives as stated above!

    PE
    ...or more than three, though I guess 3 is the bare minimum to obtain a true white...

    Which makes me wonder whether r,g and b sep negatives really are the optimal three.
    "Only dead fish follow the stream"

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  4. #34
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    Actually, you can get a true white with 2, but you need at least 3 to get a true black! That is, unless you mess with the dyes themselves. You can do this with the pseudo Kodachrome that I described above. But then you are back to the old 2 dye color processes with bad greens or blues and bad flesh tones.

    PE

  5. #35
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    Ah, I wasn't thinking of the negative process necessarily, but in any case, whether positive or neg printing process is the goal, it seems like 3 is minimum for true white and true black!

    I wonder if ciba process might be better with sep positives than normal slide films. Just because the b&w process gives such fine contrast control in development. Just a stray thought.

    You know, when I was going through Jack Mitchell's stuff after he passed, I found some glorious positives on glass. I wonder what they were, how they were made. They are fantastic. 2 1/4" squares as I recall. My guess is that they date from before 1960 or so, I could probably find some date clues on his boxes.
    "Only dead fish follow the stream"

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  6. #36
    Greg Davis's Avatar
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    You could make separation negatives using 4 color CMYK if you want more work. I would like to find more information about the ill-fated Heliochrome process.
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  7. #37
    Greg Davis's Avatar
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    Quote Originally Posted by Ektagraphic View Post
    So it is not possible to take a black and white negative, place it in the enlarger, place a piece of paper, expose the paper with one color filter and repeat this process rexposing the paper with however many filters are needed?
    If you use a single B&W negative and print on RA4 paper using the three filters in turn, you get a black and white image. That is because the paper is receiving an equal exposure of each area in the three colors. By exposing three negatives in the camera through each filter respectively, you are creating images that have more or less exposure in different areas due to the color of the scene and the subsequent filtration.

    Here I have an original color negative, three separation negatives through the appropriate filters and the resulting color image. The others are the separation negatives using no filters and a "color" print from these negatives, but printed through the filters. It is the same result I would get if I printed the same B&W negative through the three filters onto color paper.
    Attached Thumbnails Attached Thumbnails color1.jpg   red1.jpg   green1.jpg   blue1.jpg   color3.jpg  

    red2.jpg   green2.jpg   blue2.jpg   color2.jpg  
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  8. #38
    Photo Engineer's Avatar
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    In general, 3 color separation printing will give better color than white light printing from a color negative. CMYK printing is not needed with photographic processes, just with printing processes using halftones. The halftone process reduces dye density such that a black "overprint" with an amber filter is needed to "fill in" the missing density.

    PE

  9. #39

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    PE,

    Could you clarify what you mean by a 'white light print'?

    Tom

  10. #40
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    White light = a bulb in an enlarger. Any CC or CP filter may be used to correct color temperature.

    Three Color = White light, no CC or CP filter and a set of sharp cutting R/G/B filters.

    All of the above should use a WR2B UV filter (sometimes built into the enlargers today) and a heat absorbing (IR) filter (which can also be built into the enlarger).

    PE

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