Light wavelength and the limits of film sensitivity

Discussion in 'Exposure Discussion' started by Theo Sulphate, Jul 16, 2018.

  1. Theo Sulphate

    Theo Sulphate Subscriber
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    We all know film is sensitive to light outside the visible spectrum, but what are the limits? How far into ultraviolet and infrared can film be made sensitive to?

    Just curious - I'm not sure if there are any practical benefits other than what we already know about UV and IR photography.
     
  2. Bill Burk

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    Ultraviolet up through X-Rays and infrared down to baking in the car.
     
  3. NedL

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    I'm going to guess there might not be limits on the high side. I'd expect x-rays and gamma rays.to be able to expose film. Although I guess if the energy level is high enough, a gamma ray might cause a cascade of particles that would damage the film :cry:
     
  4. AgX

    AgX Member

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    Not quite. That spectral sensitivity is not continuous.
    For instance at the UV range there soon is the obstacle of opacity of the binder, about 250nm. For IR the nominal limit is at about 1200nm, however with ultra-long exposure times something in the region of 50,000nm is possible.
     
  5. It is not only not necessarily continuous it varies on sensitivity.
     
  6. Berkeley Mike

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    Sensitivity by what? Film as we now understand it?
     
  7. glbeas

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    I’ve heard of that with uv photography. The researchers were using an etching technique to remove the gelatin from the surface of the emulsion to expose the silver halide grains and improving the sensitivity at those wavelengths. That article was a lot of years ago, cant remember who was doing it.
     
  8. Berkeley Mike

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    Cool info!
     
  9. mshchem

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    I use toy IR goggles. It has potent IR LEDS as illumination source. I can stare at any non IR film for a half hour with ZERO effects (arms length from the source ). Film manufacturers don't stumble around blind. From what I've been able to find there are areas that IR is used to view what's going on. Emulsions are brilliant white on my LED viewscreen on the goggles. Black marker ink is white, Jobo reels are brilliant white.
     
  10. michr

    michr Member
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    I've been wanting a pair of these goggles myself. I hate stumbling around in the dark. What kind do you have?
     
  11. mshchem

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    Don't try walking around. Very narrow angle of view single lens, no depth perception. Jakks Pacific Spy Net night vision "binoculars " I bungee these to my head, you look like an idiot, but no one else can see you . I can read the part numbers on Jobo stuff. Amazing toy, around 60 bucks.
    20151010_164402-1-1_resized_2.jpg
     
  12. michr

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    Awesome, thanks for responding. Those googles look like pure science fiction.
     
  13. mshchem

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    The duct tape is covering the LEDS that are near IR.they put out dim red light . The other LED array is pure IR. No problem.
     
  14. michr

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    Good to know. Did they fog film before you put on the duct tape?
     
  15. mshchem

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    Nope, I didn't try . I have a IR flood light that I tried for a while ,but I went back to the built in. All the security stuff now you can get all kinds of things.
     
  16. OP
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    Theo Sulphate

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    So with presently available or specialty film stock, the answer seems to be 250nm to 1200nm with 50,000nm in extreme circumstances.
     
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