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  1. #1
    Craig's Avatar
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    Ilfochrome as an original?

    After PE's comments this morning about working on a colour process, I got to thinking (dangerous, I know). Is there any reason that I couldn't use a sheet of Ilfochrome in my 8x10 camera and shoot it instead of film, to produce a first generation image to hang on the wall, rather than having to print a transparancy?

    Would there be an issues of excessive contrast? Obviously, it would be the only copy, but I could also shoot a sheet of film at the same time to have a film original for future printing.

  2. #2
    Photo Engineer's Avatar
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    Craig, final contrast of a print is the product of the slope of the print material x the slope of the film. In this case it would be approximately 0.9 x 1.7 = 1.5. You see the print must have more contrast than the original for the eye to percieve it as being 'correct'. Therefore, in this case the starting contrast of 0.9 might be too low for you.

    In a negative positive system, the contrast would be about 2.5 x 0.6 = 1.5, so the starting contrast would be 2.5 or too high.

    PE

  3. #3
    Craig's Avatar
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    Intersting, so the initial contrast of the scene would produce a print with low contrast? Who would have thought a flat print would ever be a problem with Ilfochrome.

  4. #4
    Bob Carnie's Avatar
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    Craig

    I have had clients do this in the past and it works quite well , with testing, you will have to colour correct the scene after the first image is processed, as well I think long exposures are required.

  5. #5
    Photo Engineer's Avatar
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    Pos print materials used as an original can reproduce scenes at low contrast just as neg print materials can reproduce it too high.

    This is just one of the reasons that they need a person called a photo engineer.

    Heh.

    PE

  6. #6
    Craig's Avatar
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    Too bad I'm a mechanical engineer, I took the wrong thing!

  7. #7
    Photo Engineer's Avatar
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    Color negative print materials have an ISO speed of about 25 with correct filtration (they are tungsten balanced) but color positive print materials are daylight balanced (therefore the cyan filtration) and are very very slow, about ISO 6 or so.

    The filter pack will be quite different. If you wish help, try posts by bujor on PN. He has used Endura in-camera. Try inverting the filter pack and exposing with 3 or 4 more stops exposure. That might work.

    It is due to the opacity of the azo dyes used in Ciba/Ilfochrome.

    PE

  8. #8
    Bob Carnie's Avatar
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    Quote Originally Posted by Photo Engineer
    Color negative print materials have an ISO speed of about 25 with correct filtration (they are tungsten balanced) but color positive print materials are daylight balanced (therefore the cyan filtration) and are very very slow, about ISO 6 or so.

    The filter pack will be quite different. If you wish help, try posts by bujor on PN. He has used Endura in-camera. Try inverting the filter pack and exposing with 3 or 4 more stops exposure. That might work.

    It is due to the opacity of the azo dyes used in Ciba/Ilfochrome.

    PE
    This sounds about right in our experience. Keep in mind that if you are shooting in daylight try to expose around the same time and lighting conditions or you are in for a whole can of whoopass.

    I would use tungston light with Lee or Roscoe filters in front of the light source for repeatability and having no filters packed in front of your lens.

    Love to hear about the results.

  9. #9
    Craig's Avatar
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    Thanks, I'll give it a try when my Cap-40 machine arrives and I get it up and running.

  10. #10
    Eric Rose's Avatar
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    Does this mean you want your 8x10 back?
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