Sheet Film Development By Inspection With Night Vision Technology

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

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

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

Sean said:

update
Well proof of concept went very well. So far I have dev'd 3 negs by IR inspection and found it a valuable tool. My next step was to improve on the process. I took apart my IR goggle's lens assembly and was shocked to find a few of the lenses covered with a layer of muck, so I cleaned them. I also found that by unscrewing one of the parts about 3 turns allowed me to focus even closer and clarity was improved. I have built a custom hood that fits over my goggle (some may have seen that in another thread I posted).

Click to expand...

Sean, would you mind updating this post with photos of your current setup? The old images from the original post have disappeared. Thanks.