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  1. #21
    Photo Engineer's Avatar
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    Ok, this might interest you but many graded enlarging papers today are ortho sensitive. This was a surprise to me too. The reason stained negatives give oddball contrast on VC papers is obvious, but the results on a graded paper are kinda unknown I guess.

    If you wish to test your paper for green and blue sensitivity, expose them through a wratten 98, 99 and 70 and this will give you the relative speeds to B/G/R light. Of course Ilford MGIV would be your reference. You may be surprised to see the results. I was.

    PE

  2. #22
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    PE,
    You may be interested to know that one of the reasons I favor PMK is because of the effect the green stain seems to have when split contrast printing. The PMK negs seem to split the hard and soft exposures more effectivly than negatives developed by other means.

    J
    Last edited by JBrunner; 01-08-2008 at 06:08 PM. Click to view previous post history. Reason: added a dee

  3. #23
    Photo Engineer's Avatar
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    Well, I can't make a VC Azo yet, but I have ideas how. I have read about what you describe though. I'm referring though to many enlarging papers having green sensitivity even though they are not VC papers. This is probably one way they are picking up some speed.

    PE

  4. #24

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    PE - a green sensitive paper that is graded, i.e. not multicontrast, will respond just fine to a stained negative. The paper can not and will not react any differently from a plain old un-stained negative. Follow the link on this page on my web site and you will see a comparison of the stain on a couple films processed in two staining developers, one in PMK and the other in Pyrocat-HD. The films are TXT320 and FP4+, but I don't think there is a significant difference in that. The films were bleached and the silver was removed, leaving only the stain behind and then the films were scanned in a spectrophotometer.

    There are two lines plotted for each film, one from a section of film base with only fog, and the other line is from a portion of the film with density - they were exposed with a Stouffer step wedge and Step 1 or 2 is used for these.

    Keep in mind that the plots are only intended to give a general idea of the stain density - the areas of film used were not matched in density nor was the development of each film matched for gamma or CI. They just happened to be the sheets I grabbed to do the test with...

    Anyway, you can see the Pyrocat really doesn't have much absorbance in the green or even the blue, especially when compared to the PMK neg. I think there will be minimal difference in exposure with a Pyrocat neg using your green-sensitive paper when compared to a blue-sensitive one, except it may be a bit quicker as it transmits a bit more light in the green. The PMK neg will probably print noticeably faster with the green sensitive paper as it has much less absorbance in the green so it should let more light through.

    I think this is what you are trying to get at, right?

  5. #25

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  6. #26
    Photo Engineer's Avatar
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    Yes, Kirk, that seems to be what I was asking. But, in that case there may be no advantage to having green sensitivity at all except for more green speed. I can make it faster without green speed. So it might just increase the effort and expense with no yield of any benefit in imaging, as the speed alone is easy to do.

    PE

  7. #27
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    The thing that I so loved about Azo was the 3-D effect one could get. In the past, PE, you've said that was a paper or base effect, not an emulsion effect. Is that still the case?
    juan

  8. #28

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    Quote Originally Posted by Photo Engineer View Post
    Yes, Kirk, that seems to be what I was asking. But, in that case there may be no advantage to having green sensitivity at all except for more green speed. I can make it faster without green speed. So it might just increase the effort and expense with no yield of any benefit in imaging, as the speed alone is easy to do.

    PE
    Yeah, that's kind of the way I see it. A neat thing to be able to do, but maybe not that useful?

  9. #29
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    One application noone has mentioned is enlargements, if it can be made fast enough.

  10. #30
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    How soon can I order a couple of hundred sheets of 11x14?

    Curt
    Everytime I find a film or paper that I like, they discontinue it. - Paul Strand - Aperture monograph on Strand

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