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  1. #51
    glbeas's Avatar
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    Sep 2002
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    Have you checked that you are not overdriving the LEDs with too much power. I've read that running them too bright will spread the bandwidth. Possibly you could use a dimmer and drop the brightness a stop or two and the red leakage will diminish appreciably. If the IR is too weak you would then want to incorporate more leds in the bank
    Gary Beasley

  2. #52
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    Fogging one film with IR and not another may indicate that the film that fogs has a longer red sensitization than the other, or that it has a higher sensitivity near the IR/Visible cutoff region of 700 nanometers.

    You can test this by taking exposures with a typical IR filter over the lens using the two films at their rated speed and seeing which one has more image from IR on it. It may require a long exposure, but this experiment would be valuable under the circumstances.

    The only other solution would be to use a spectrosensitometer to test the spectral senstivities of both films.

    PE

  3. #53

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    As time and money allow I will investigate the possibility of using 940nm LEDs and or an IR pass filter. When and if I find out anything interesting I will post here again.
    Art

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