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  1. #471

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    Lets just forget about trying to process the film and work on the Wiki instead.
    Documentation is the key

  2. #472
    lxdude's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    I have to scream this from the rooftops I guess.

    POS-POS print systems have an inherent flaw. You are basically multiplying the slope of one curve by the slope of the other curve, (original slide x print material) to get the final dupe image. If your original has a perfect capture and a slope of 0.3, and if the print material also has the same slope, the result is a slope of 0.09, which is a reduction in contrast. This is why you must use masks to adjust contrast and masks to adjust color.

    I thought contrast increase is the problem in a pos-pos process. Now I'm confused.
    I do use a digital device in my photographic pursuits when necessary.
    When someone rags on me for using film, I use a middle digit, upraised.

  3. #473

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    Quote Originally Posted by lxdude View Post
    I thought contrast increase is the problem in a pos-pos process. Now I'm confused.
    I have a few of my Dad's (shop made) prints-from-transparencies from the 1960's to 70's which are very soft and "milky" in colors and contrast.....I remember he was never really satisfied with them.

  4. #474

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    So, what we really could do with is a list of tips for using Portra (sheet, roll or 135, as appropriate) as an interneg or dupe film, in order to print from transparencies on to RA4.

    Several decades ago this was a standard part of our lab work, but there was/were specialist interneg film(s) from Kodak for exactly this purpose - they were discontinued years ago of course.

  5. #475
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    Quote Originally Posted by MartinP View Post
    So, what we really could do with is a list of tips for using Portra (sheet, roll or 135, as appropriate) as an interneg or dupe film, in order to print from transparencies on to RA4.
    Supposedly you can cook up a special developer which turns RA4 paper into pos-pos material.

    Still, neither Ilfochrome, nor pos-pos RA4, nor inter negatives will develop those outstanding Kodachrome rolls ...
    Trying to be the best of whatever I am, even if what I am is no good.

  6. #476
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    Quote Originally Posted by lxdude View Post
    I thought contrast increase is the problem in a pos-pos process. Now I'm confused.
    Ok, a reversal (1.5 gamma) printed onto the same stock is 1.5 x 1.5 or a final mid scale gamma of 2.25, a gamma increase in the mid scale, but in the toe it might be 0.3 so 0.3 x 0.3 = 0.09 which is a decrease. The scales are all out of whack.

    A true print material is gamma 1.0 so that the mid scale stays the same, but still, the toe suffers. Whichever way, the dupe gets what we in the trade call a "dupey" look.

    PE

  7. #477
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    Quote Originally Posted by MartinP View Post
    So, what we really could do with is a list of tips for using Portra (sheet, roll or 135, as appropriate) as an interneg or dupe film, in order to print from transparencies on to RA4.

    Several decades ago this was a standard part of our lab work, but there was/were specialist interneg film(s) from Kodak for exactly this purpose - they were discontinued years ago of course.
    Use about a 100C and 50 M in your enlarger to simulate daylight and use about a 1/2" exposure at F22. This should make a nice 3x4 onto Portra 4x5 from a 35mm.

    For process, pull using a 3' development time or a 2' 45" development time to reduce contrast.

    PE

  8. #478
    Ken Nadvornick's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Ok, a reversal (1.5 gamma) printed onto the same stock is 1.5 x 1.5 or a final mid scale gamma of 2.25, a gamma increase in the mid scale, but in the toe it might be 0.3 so 0.3 x 0.3 = 0.09 which is a decrease. The scales are all out of whack.

    A true print material is gamma 1.0 so that the mid scale stays the same, but still, the toe suffers. Whichever way, the dupe gets what we in the trade call a "dupey" look.

    PE
    So then dedicated duplication films would have been designed to counterbalance these "out of whack" realities? Or at least attempt to lessen them?

    Ken
    "Hate is an adolescent term used to stop discussion with people you disagree with. You can do better than that."
    —'blanksy', December 13, 2013

  9. #479
    MattKing's Avatar
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    Quote Originally Posted by Ken Nadvornick View Post
    So then dedicated duplication films would have been designed to counterbalance these "out of whack" realities? Or at least attempt to lessen them?

    Ken
    And probably slower and very fine grained as well.
    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

  10. #480
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    A dedicated color internegative film did have an upswept shoulder that fixed the toe problem evening it out, and the mid scale was the standard 0.6 of negative films. And thus, it made an excellent positive. In fact, since the neg-pos system could produce Dmax values of 4.0 or hither, the transparencies produced were brilliant. No E6 (or any reversal film) can produce a Dmax higher than about 3.0.

    For evidence, look at any E6 film and then look at the Vision Print Film for Dmax comparisons.

    PE



 

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