Re:IR lighting

Bill Woodland (wcw@bga.com)
Tue, 13 Aug 1996 23:28:29 -0500


>Date: Tue, 13 Aug 96 21:43:18 -0400 (EDT)
>Reply-To: fneirab@amauta.rcp.net.pe
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>From: "Francisco Neira B." <fneirab@amauta.rcp.net.pe>
>To: <CU-SEEME-L@cornell.edu>
>Subject: IR lighting
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>At 19:11 13/08/96 -0400, you wrote:
>>A long the same lines, has anybody done any testing with the Quick Cam using
>>infrared illumination? I've seen references to them "seeing in the dark" and
>>have found that they do "see" the IR output from a TV remote. Anybody have
>>more info?
>>
>Hello,
>Your idea sounded so interesting for me that a few moments ago, here at home
>I made an experiment.
>
>On a dark room, I turned on an Infraphil Phillips infrared lamp (150W) and
>aimed the QuickCam to the same target. Result: An image with better
>definition than with normal incandescent lamps. Shortcoming of the test:
>This lamps have a *lot* of visible red components, because are the ones used
>for medical purposes, and not intended to be pure IR sources.
>
>Tell me if you can set better testing conditions.
>Regards,
>
>
>Francisco
>"Be thankful for problems. If they were less difficult, someone with
> less ability might have your job"
> - Bits & Pieces
> Francisco Neira
>Computer Programmer/Network Administrator
> Lima - Peru, South America -5:00 GMT
> Data/Voice +51(1)460-0627
>
>
>

I tried it myself with my remote control...yea, it works...all you et is a
little white dot where the IR led is, but the quickcam isn't sensitive
enough to pick up a human body just by its heat.

I have read somewhere that the quickcam has an IR filter built into it, and
that you can get some better pictures with less light if you remove it. I
think it was at this URL:

http://aleph0.mit.edu/~lars/qcamstuff.html

but it seems to be down right now, so I can't check it to be positive.

IF you are so inclined, you will have to open the ball, remove the circuit
card, and unscrew the two screws that hold the focusing lens holder over the
actual IC chip. The filter is an almost clear piece of plastic, thinner,
but not unlike the kind used in cheap sunglasses.

You can see pictures of what I'm talking about at this URL:
http://hagbard.ncsa.uiuc.edu/quickcam/guts.html

Once you screw the lens mount back on, be sure to check the focus...you may
have altered the distance slightly when removing the filter. If so, you
will need to loosen the setscrew that holds the lens barrel in place, and be
sure to focus on something that is at least a foot away. I made the mistake
of focusing on my beard, up close, so I could see the individual hairs, but
once I got it all back together, everything further away than a few inches
was blurred, and I had to do it again.

Ah well...you don't learn if you don't experiment :)

Bill Woodland (wcw@bga.com)
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