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  1. #41
    Rafal Lukawiecki's Avatar
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    I only have a short experience of using a densitometer, but, so far, I found the Heiland TRD-2 to be very repeatable for both negative transmission, and glossy fibre paper reflection measurement, usually within 0.01 and never more than 0.02 spread.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

  2. #42
    ic-racer's Avatar
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    Let me be rephrase my comment. Too many variables affect photographic paper's D-max to make reflection sensitometery reliable in choosing the contrast level of a printing paper in my darkroom.

    I did not mean to indicate the instrument was mechanically unreliable, but the results cannot be relied on to give useful information in my printing technique.

    Ok, try this. Make a test strip that goes to maximum black on the paper but keep blasting it with additional strips of exposure. Lay the processed and dried paper on an opaque surface and check for the darkest strip, now hold it up to the light. You can now see all those darker bands. So, even how you hold a print to view it influences D-max. Let alone effects of toning, print drying technique, angle of viewing, etc. To rely on reflection sensitometer results for choosing paper grade, all that has to be taken into account. I'm not saying that all can't be done. Just that I use my eyes to zero in on the correct exposure and filtration when making a print.
    Last edited by ic-racer; 10-22-2012 at 10:33 AM. Click to view previous post history.

  3. #43
    Photo Engineer's Avatar
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    Reflection densitometry is an exact science. The mid scale variations are a measure of contrast, not the Dmax. Dmax is limited by the laws of physics causing it to fall between 1.8 and 2.2 depending on surface. In normal viewing conditions, this range can be seen, but anything over that, visible by transmission, is not seen by reflected light. This goes for color or B&W. However, again due to the laws of physics, in color there is a slight hue shift past the reflection cutoff limit.

    So, you can trust reflection readings with most any good densitometer. At EK in KRL, we used Macbeth units.

    PE

  4. #44

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    Looks like a fun project, but I certainly wouldn't try to extrpolate the results over different kinds of
    b&w films, which in instances can be siginificantly affected by the color of light. Another problem is
    that old-school bulbs for spectrophotometers and gear like this were actually "broken in" by burning
    a number of hours before sale in order to reach a plateau of lumen and spectral output. The you were supposed to keep track of the number of hours of use for when to replace them, and not when
    they actually burnt out.

  5. #45

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    Quote Originally Posted by ic-racer View Post
    I did not mean to indicate the instrument was mechanically unreliable, but the results cannot be relied on to give useful information in my printing technique.
    That's sort of what I meant when I said, "I think there is just less need for these things [reflection densitometer], with respect to a regular photographer." You're just not finding a practical use for it.

    The situation might change if, for example, you found that you preferred the "look" of one paper to another, and wanted to study it to find out why. Maybe it's due to a subtle difference in mid-tone curve shape, which you could discover through sensitometry. On the other hand, the person I call the "regular photographer" might just say, "I like this paper better; I don't really care why, but this is the paper I'm going to use."

    For myself, I've found reflection densitometers very useful in doing technical work for a large user (industrial scale) of photo materials. For myself as a regular photographer, not so much use.

  6. #46

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    Reflection densitometers are more likely to be used for process control in color work, whether monitoring chemistry or tinkering with alt processes, etc. Also needed in traditional graphics work.
    I doubt the average silver darkroom would have much use for one. However, I use a transmission
    densitomer as well as a projection densitometer a great deal.

  7. #47
    ic-racer's Avatar
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    Quote Originally Posted by DREW WILEY View Post
    different kinds of
    b&w films, which in instances can be siginificantly affected by the color of light. .
    Which one would you like me to try? If the spectrum response is too weirdo then it may not be good for much. X-ray films are pretty weirdo in the respons but would be perfectly suited to the colored LEDs.

  8. #48

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    Try TMX. I already know what to expect - I doubt you'll do several months testing on it like I did,
    including batch consistency. It's fairly unique in certain respects, but it would be interesting to see
    if you land upon it with your particular vintage of gear. Regardless of the outcome, these kinds of
    gadgets are fun to learn about.

  9. #49
    ic-racer's Avatar
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    Quote Originally Posted by DREW WILEY View Post
    vintage of gear.
    ?

    The ESECO units tested here are new production.
    http://www.eseco-speedmaster.com/sl-2.pdf

  10. #50
    ic-racer's Avatar
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    This is a scaled composite of the spectral sensitivities of FP4, Tri-X and TMX. Based on these curves I'd predict all 4 sensitometers will give useful information about the speed differences between the three.

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