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  1. #1
    Jeff Bannow's Avatar
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    Sensitometers - will an X-ray unit work for film testing?

    Sensitometers - will an X-ray unit work for film testing? I assume not, since they are designed for blue or green. But they are on eBay for cheap, so I thought I would ask.

    I haven't seen an EG&G sensitometer available for under $600, and even then there's usually no guarantee that it actually works.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

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    I don't understand your post. X-ray machines do not produce any visible light. Now the phosphors in the viewing screen do create an image but that is something entirely different. How would you propose using such a machine?
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  3. #3
    Photo Engineer's Avatar
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    No, it will not work!

    PE

  4. #4
    Jeff Bannow's Avatar
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    Quote Originally Posted by Gerald C Koch View Post
    I don't understand your post. X-ray machines do not produce any visible light. Now the phosphors in the viewing screen do create an image but that is something entirely different. How would you propose using such a machine?
    Sorry for the confusion - there are a lot of X-ray sensitometers available on the market for very cheap - $50 or less in working condition.

    Quote Originally Posted by Photo Engineer View Post
    No, it will not work!

    PE
    Thanks PE! That's what I was afraid of.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  5. #5
    Greg Davis's Avatar
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    I've wondered about those and whether they are LED's. If so, could they be swapped out with more appropriate lights for b&w?
    www.gregorytdavis.com

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  6. #6
    Jeff Bannow's Avatar
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    Quote Originally Posted by Greg Davis View Post
    I've wondered about those and whether they are LED's. If so, could they be swapped out with more appropriate lights for b&w?
    Some of the models are listed as being LED. No idea on swapping them out though.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  7. #7

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    Answer is yes, no, maybe, with the caveat of how much do you want to spend. And are you confusing sensitometer with densitometer?

    do they do the same thing-- yes
    will it give an accurate result--no
    can you swap LED's---maybe-- but you will have to recalibrate the entire machine for the new light source, how much are you willing to spend?

    http://www.unblinkingeye.com/Articles/Densi/densi.html
    * Just because your eyes are closed, doesn't mean the lights in the darkroom are off. *
    * When the film you put in the camera is worth more than the camera you put the film in... *
    * When I started using 8x10, it amazed me how many shots were close to the car. *

  8. #8
    Jeff Bannow's Avatar
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    Sensitometers - will an X-ray unit work for film testing?

    Quote Originally Posted by Jeff Searust View Post
    Answer is yes, no, maybe, with the caveat of how much do you want to spend. And are you confusing sensitometer with densitometer?

    do they do the same thing-- yes
    will it give an accurate result--no
    can you swap LED's---maybe-- but you will have to recalibrate the entire machine for the new light source, how much are you willing to spend?

    http://www.unblinkingeye.com/Articles/Densi/densi.html
    Already have a xrite 361t.

    Definitely need a sensitometer, but not enough to replace all the LEDs and recalibrrate.
    - Jeff (& sometimes Eva, too) - http://www.jeffbannow.com

  9. #9
    Bill Burk's Avatar
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    Jeff Bannow,

    If you are interested in making your own sensitometer:

    You want to make something that will expose a Stouffer step wedge in contact with film for a time between 1/1000th second and 1 second, with a light source corrected for daylight.

    Do you have any of these things lying around? You can make a sensitometer out of any of them...

    - Light Integrator (tallies the amount of light received at a sensor). Examples: Zone VI Compensating Enlarger Timer or Compensating Metronome. RH Designs StopClock Vario.

    - Voltage Stabilizer (tungsten) or Stabilized Enlarger Head. Example: Zone VI

    - Shutter accurate around 1/100th second. Example: Minolta X-700 body

    - Variable output electronic flash. Example: Vivitar 283 with VP-1 Varipower module

    ---
    Don't abandon the idea of having a sensitometer just because a "calibrated" system is out of reach. Being consistent can be just as good as being "right." For example, with my uncalibrated EG&G and uncalibrated Macbeth TR524, I have been asking myself (and in some threads) whether my results are really 2/3 stop away from where I thought they were. But my results for any film/developer combination are satisfyingly consistent with each other.

  10. #10
    ic-racer's Avatar
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    It should work fine. If the slope of your gamma responds differently to development when exposed to, say green vs blue vs red then there is something wrong with the manufacture of the film.

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