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  1. #21

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    Quote Originally Posted by Rafal Lukawiecki View Post
    Do you have a similar, prior experience with a Kodak Process Control Sensitometer? I'm not familiar with any of those, but looking for one.
    Rafal, many years ago, I used a Kodak Process Control Sensitometer (model 101, I think) quite a lot, so could answer some questions on it. Basically it's a fairly large, heavy machine using an expensive tungsten lamp. (They were expensive because each bulb came with a calibration certificate, listing the mount-position specs, as well as operating amperage at a spec'd color temp.) The sample mounting platten is curved, presumably in an arc around the lamp filament position. Exposure is a single time, ~ 1/5 second(?), via a rotating disc shutter with a cutout sector. They came with a 2-step inconel-coated filter, so you had two density steps to choose from (removing the filter was another option). Finer adjustments were done with gelatin filters in a filter drawer. That's pretty much about it.

    In my job, we used it for paper testing, but found the exposure-time limitation too restrictive. We had it modified with a stepper motor to rotate the shutter disk, so we could dial in different times to match the machine printers we used. I'm not sure that one of these sensitometers has much practical use today.

  2. #22
    Rafal Lukawiecki's Avatar
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    Thank you Mr Bill, and thank you IC. I seem to have just picked up a Speedlight SL-2 on that site, driven mainly by the thoughts expressed on this thread. I am looking forward to trying it when it arrives, assuming it is in a working order.

    By the way, the Kodak unit looks very similar to X-Rite 394, judging from photos, but I do not see the model number on it.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

  3. #23
    Bill Burk's Avatar
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    Quote Originally Posted by ic-racer View Post
    Should be easy to do. I think it will turn out OK. The Wejex in the test had an exposure time of 1 sec and the EG&G was set to 1/1000. There was not detectable difference in the way the exposed film responded to development time changes between those two. So, I suspect 1/10,000 would be similar.
    I am just curious because common advice to compensate for reciprocity failure is to develop 10% longer when using 1/1000 second. So if that advice is based on sensitometry, a 1/1000 curve should have a lower gradient than a curve exposed for 1/100 second (and developed for the same time).

    You were on 10^-3? (I usually use 10^-2).

  4. #24
    Rafal Lukawiecki's Avatar
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    How do you control the exposure of your ESECO Speedlight SL-2, if I may ask? I was hoping to use it with both 400 and 100 film, and it would be great if I could get the entire set of steps, except for the first one or two, exposed enough to read a density above fb+f. Do you use filters, multiple exposures, or a modification of some sort?
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

  5. #25
    ic-racer's Avatar
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    Quote Originally Posted by Bill Burk View Post

    You were on 10^-3? (I usually use 10^-2).
    Tests were done at 10^2, 1/100. Earlier post is a typo, thanks for catching that.

    Bill you should be able to test that. You don't need the EG&G line filters, just any ND to get both exposures somewhere on the step wedge to plot a slope.

  6. #26
    ic-racer's Avatar
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    Quote Originally Posted by Rafal Lukawiecki View Post
    How do you control the exposure of your ESECO Speedlight SL-2, if I may ask? I was hoping to use it with both 400 and 100 film, and it would be great if I could get the entire set of steps, except for the first one or two, exposed enough to read a density above fb+f. Do you use filters, multiple exposures, or a modification of some sort?
    There is a trimmer resistor for each color. The two units I'm using came 'factory calibrated' and I don't see a good way to set the trimmer back after changing it, so I have not altered these units.

    There is some extra density material over the LEDS that could be removed to move the step wedge exposures when exposing slower film.

  7. #27
    ic-racer's Avatar
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    Forgot to say that Jeff Bannow has kindly donated the two Speedlight SL-2 units for the test.

  8. #28
    Stephen Benskin's Avatar
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    I don't know if anyone has heard of the Gamma-Lambda effect. I did a little research into this sometime ago. Average gradient is affected by the wavelength of light. Blue light tends to decrease the gradient while green tends to increase the film gradient. Red and white light tends to fall somewhere in between. My tests confirmed this. I tested nine films using tri-color filters with my EG&G. Hold times were identical and the film was processed together in a dip & dunk. The differences weren't great but there were differences.

    This is an example from the those tests.

    Click image for larger version. 

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  9. #29
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    Stephen;

    I have mentioned this before.

    PE

  10. #30
    Stephen Benskin's Avatar
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    Sorry, I didn't know you've already referenced my paper.
    Last edited by Stephen Benskin; 10-15-2012 at 10:26 PM. Click to view previous post history.

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