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Old July 11th, 2003, 02:43 AM   #1
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Filming in "infra-red"

Anyone know how I can film digital video in infrared (infra red) so I can get the kind of effects shown on education programmes that show heat rising, heat foorprints on carpet. Colour would nice.

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Ian
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Old July 11th, 2003, 07:17 AM   #2
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This website covers the topic pretty thoroughly. Although it's oriented towards still digital cameras it should be applicable. With my VX-2000 I tried the "tv remote" test they suggest, and the IR emitter was visible as a bright flickering hotspot.

This is something I also want to play around with "someday" when I can find the time. Let us know what kind of results you achieve!
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Old July 11th, 2003, 08:47 AM   #3
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Thanks for the suggestion.

I'm having problems getting through to the Website you suggest. Could you double check the Web address?

You have:
http://www.cliffshade.com/dpfwiw/ir.htm

Regards,
Ian
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Old July 11th, 2003, 09:11 AM   #4
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Website is working fine on my end!
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Old July 11th, 2003, 09:30 AM   #5
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Yes, it seems that the site is just VERY slow at my end.

I've since done some Web research, and found the following sites on infrared and digital photography, though it anyone can help with any pointers for colour infrared video, I'd be interested.

Resources

Infrared Photography FAQ
http://www.cocam.co.uk/CoCamWS/Infrared/INFRARED.HTM

ECHENG.COM: Digital Infrared Photography
http://www.echeng.com/photo/infrared/

Infrared Photography Some Personal Experiences
http://www.pauck.de/marco/photo/infrared/infrared.html
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Old July 11th, 2003, 11:19 AM   #6
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Sony's latest NightShot is said to do color. Don't know how they are doing it.

Most colored IR images you see are generated by the computer assigning color to different levels of grayscale.

Probably the quickest way to try this is to use a NightShot-equipped camera and then color the different luminance levels in a different color.

A 'regular' camera will still see IR because the IR filters they use are just bulk-dyed glass, not sharp cutoff. To have IR the predominant contributor to the image, you need to place a visible light filter over the lens. You've probably seen them, they look red either on the surface or when looking through them. Probably a simple red photographic filter would help although not be perfect.

Of course you can always get a cheap camera, take it apart and remove the IR filter. I'm not certain what that would do to the optics (every change in the optical path changes the focus point) but then IR does not focus at the same point as visible light when using a normal lens designed for visible light.

Film cameras will sometimes have an IR focusing mark on the lens barrel. You focus the camera and then move the focus ring a certain number of degrees from that point.
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Old July 11th, 2003, 12:00 PM   #7
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Yes, I't be interested to know whether Sony's Nightshot mode willl show (a) hot steam rising from a saucepan, perhaps with the help of a polarising filter (b) footprints across a carpet?

Ian
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Old July 11th, 2003, 12:13 PM   #8
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Maybe the hot steam. Don't know why a polarizing filter would help. But I don't know much about IR light and how it can be polarized or whether polarized light would be naturaly given off by steam.

Hot footprints? I don't think so. That would probably take a cooled CCD to get to the low level of CCD noise necessary to see that in the background. Then the issue of sensitivity comes up. How much gain have you available in the video amp.

Almost all of the salt and pepper noise you see in a dark video image is from CCD leakage currents generated at room temperature. The higher the temperature, the more current. That's one of the reasons for an upper temperature limit on camcorders. And one of the reasons why a camcorder that has a good CCD at room temperature (good=no bright pixels) may exhibit a bright pixel at elevated temperatures.

Astronomers use CCDs to image the heavens but the way they get the very low noise is to cool the CCD with liquid Nitrogen or some similar liquid. Amateurs sometimes cool their cameras with dry ice (the CCD, not the mechanicals and not the battery).
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Old July 11th, 2003, 12:16 PM   #9
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I think what I am after is "thermal imaging". Andy Finney's page at http://www.atsf.co.uk/ilight/tech/ilightec.html says:

"Infrared imaging is often used to detect heat loss and to find people by their body heat. This is far infrared thermal imaging, of a longer wavelength than the near infrared light used in these photographs. Far infrared is detected electronically rather than by using film."

Ian
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Old February 14th, 2004, 09:36 AM   #10
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Modifying regular camcorders.

"Of course you can always get a cheap camera, take it apart and remove the IR filter. I'm not certain what that would do to the optics (every change in the optical path changes the focus point) but then IR does not focus at the same point as visible light when using a normal lens designed for visible light."

Yes I did this with a cheap JVC mini DV camcorder once. The optics is a problem. I had to move the CCD closer to the lens because the green/blue filter was now missing and changed the optics.

I am going to try this again and I think I will use IR glass so the optics stays similar and hopefully I can work it out with a few washers and trial and error.
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Old February 14th, 2004, 10:11 AM   #11
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It looks like it is Thermal Infra Red that I am after, and a good source of cameras is www.x20.org

Unfortunately their customer service is rubbish... I've never received a reply from them.

Regards,
Ian
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