Sheet Film Development By Inspection With Night Vision Technology

[glbeas]

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

 

[Photo Engineer]

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

 

[Sharadn]

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

 

[ParkerSmithPhoto]

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).

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