Sensitometers - will an X-ray unit work for film testing?

Discussion in 'B&W: Film, Paper, Chemistry' started by Jeff Bannow, Sep 28, 2012.

  1. Jeff Bannow

    Jeff Bannow Member

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    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.
     
  2. Gerald C Koch

    Gerald C Koch Member

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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?
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    No, it will not work!

    PE
     
  4. Jeff Bannow

    Jeff Bannow Member

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    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.

    Thanks PE! That's what I was afraid of.
     
  5. Greg Davis

    Greg Davis Member

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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?
     
  6. Jeff Bannow

    Jeff Bannow Member

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    Some of the models are listed as being LED. No idea on swapping them out though.
     
  7. Jeff Searust

    Jeff Searust Member

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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
     
  8. Jeff Bannow

    Jeff Bannow Member

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    Already have a xrite 361t. :smile:

    Definitely need a sensitometer, but not enough to replace all the LEDs and recalibrrate.
     
  9. Bill Burk

    Bill Burk Subscriber

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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. ic-racer

    ic-racer Member

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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.
     
  11. Jeff Bannow

    Jeff Bannow Member

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    Thanks for the suggestions Bill. I decided to buy a unit off ebay to test (only $25, so it's worth looking at). If it doesn't work out, then I'll look into an alternate method.

    I would think something like the RH designs paper flasher would work also?