using infrared film in caves

[MichaelAngelo]

thanks for all the great imfo
I was unable to find the film anywhere. Seems like its out even nYC and Heliex in Chicago. Maybe next trip
MA

[crazyduck]

You might be interested in this.
http://www.echeng.com/photo/infrared/

This is Eric Cheng- he started wetpixel.
He has a whole section on infrared with digital cameras and filters.

Andrew

[Squirrel Girl]

Has anyone else tried infrared in caves? If so, what was the result? Can you even buy it in High Springs/Lake City/Gainesville area?

I'm guessing that it might be neat in an air-filled cave but everything in an underwater cave would give off IR at nearly the same rate.

Just an educated guess though.

This sounds logical to me. I'd love to see someone try it and find out if anything BUT this would result. Though actually, why wouldn't it be true in an airfilled cave as well?? With no sunlight, or any other heat source, how could there be any thermal differences? That is human subjects aside.

And I tend to think in the longwave. I'm not sure if there'd be any effect in the near IR.

I'm gonna post up in the air-filled cavers' forum now.

[Gary]

I'm guessing that it might be neat in an air-filled cave but everything in an underwater cave would give off IR at nearly the same rate.

This sounds logical to me. I'd love to see someone try it and find out if anything BUT this would result. Though actually, why wouldn't it be true in an airfilled cave as well??

For the reflected IR I imagine you'd probably need an IR lamp since you wouldn't have a IR source in a cave.

For emitted IR water would be an emitter and with everything at the same temperature that's all you'd get underwater.

Air as a gas I think is too diffuse to act a a major emitter of IR so IR in an air filled cave you should be able to pick up other cavers, any hot blooded animals - maybe even foot and hand print and such. I wouldn't be surprised that a good system could pick up enough temperature variation to pick out different areas of rock - enough to "see" the cave shape.

I have had experience using IR systems in smoke/flame filled building and such. Once again the air is thin. You can see through hot air to the flames or people beyond. You can find people behind curtains etc.

I once found a bunch of videos on the internet can't fand anything good today though.

[Webmaster]

What he was talking about was not thermal IR. If you really want to do thermal, you can get a handheld thermal IR imaging device much cheaper now, although they're still around $5k.

Photo strobes are excellent sources of IR light, and I believe HID bulbs give off a great deal of near IR as well. (In addition to the visible light given off by both of course.)

The question would be if the reflected near IR would actually make it back to the camera underwater, or would it be filtered out by the water? Trying it with a digital camera and filter first would probably be the way to go before purchasing some film.

Marbry