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  1. #31
    Photo Engineer's Avatar
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  2. #32
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    Quote Originally Posted by Michael Kadillak View Post

    Dilute Pyrocat with T Max 400 utilizing stand or semi stand process generates an extended long toe and an emphasized S shoulder to such a degree that you would swear that this could not be the same emulsion. I am sure that there are many other examples that fit this model.
    Might this be backwards? My way of thinking, SS film development would produce a sharp rise into the straight line with a long soft shoulder
    Real Photographs are Born Wet !
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  3. #33

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    Quote Originally Posted by keithwms View Post
    I'll be doing some tests at ~325 in the coming weeks.
    A nice change of pace from the too often IR posts. From
    ages gone by there are photos where depth is dramaticaly
    emphasized by UV fading of far distant portions of the
    scene. Dan

  4. #34

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    Quote Originally Posted by dancqu View Post
    A nice change of pace from the too often IR posts. From
    ages gone by there are photos where depth is dramaticaly
    emphasized by UV fading of far distant portions of the
    scene. Dan
    Dan,

    I do not follow, could you expand on this a bit?
    Ray

  5. #35

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    There seems to be a mixup of threads here, no?

  6. #36

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    Quote Originally Posted by Paul Verizzo View Post
    There seems to be a mixup of threads here, no?
    I think I interrupted an on-going conversation when I discovered the death of your Kodak links.

    Beyond that I am not sure.

    And, I was wondering what Dan had in mind when he wrote:

    From ages gone by there are photos where depth is dramaticaly
    emphasized by UV fading of far distant portions of the
    scene.

    hummm... I see, it's not an issue of conservation of old photographs, (fade)
    but one of image-wise exposue of fresh film
    to UV+vis
    w/o use of UV filter,

    and how such images appear.

    Sorry....

  7. #37
    Marco B's Avatar
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    Quote:
    Originally Posted by ath View Post
    When comparing spectral sensitivity it is important how they were derived. There are at least two "standard" ways to plot the graphs. Based on the same data they look completely different.
    Compare the spectrae at page 3 for these two datasheets (german and english version of the same film, Ilford Delta 100): http://web.archive.org/web/199806101...00_Delta_G.pdf and http://web.archive.org/web/199806101.../100_Delta.pdf
    Interesting. Other than I just stuck with English language data sheets, I don't know what to say. Why would Ilford use and publish two different methods?

    Quote Originally Posted by Paul Verizzo View Post
    Interesting. Other than I just stuck with English language data sheets, I don't know what to say. Why would Ilford use and publish two different methods?
    Looking at these coarse graphs, I have the distinct feeling they may just not be very accurate. I am always very wary of simple curved graphs not showing original measured data points, as the data may simply have been drawn freehand through a very limited set of points.

    The general "look" of these graphs between 450nm and 650 is about the same. It may well be that there aren't actually any true measured data points below 450 nm, and one guy decided to extrapolate the curve as in the German document, suggesting a high UV and blue sensitivity, while another person decided to drop the curve to 0 as in the English document...
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  8. #38

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    Quote Originally Posted by Ray Rogers View Post
    Dan, I do not follow, could you expand on this a bit? Ray
    Passing light in the red and longer wave lengths
    reduces distant haze while while passing light in
    blue and shorter wave lengths increases haze.

    Most films have good blue and UV sensitivity.
    Haze accentuates depth differently than
    depth of field. More realistic IMO. Dan

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