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Ultra-Low-Cost Infrared Digital Photographyin Tutorials |
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By ram5/Richard (2,016) 
on October 13, 2002 4:27:27 AM CDT
The Camera The CameraThere is a little toy digital camera called the JamCam that is to digital cameras what the Holga 120 is to film cameras. The Holga doesn't have optics by Schneider or Carl Zeiss, and it isn't really much more than a plastic box with a fixed shutter, limited aperture control, a marginal lens, and a film advance knob. But it has been a fundamental tool for teaching photographic composition for years. Without the distractions of camera adjustments or automatic-everything, students can concentrate on composition. Check out the hundred or so pictures posted to PhotoSIG by Holga 120 users to see what I mean. The JamCam takes modest 640 by 480 pictures (about a third of a megapixel) that are over-saturated, not overly sharp, and have an odd look about them that makes a JamCam shot easy to spot. The camera has a built-in flash, a socket for expansion memory, and connects to your computer through either a serial or USB port. It's not a camera that most PhotoSIG visitors would give a second glance, but look at the JamCam shots that Tamara M posted to PhotoSIG before you dismiss it entirely. Tamara proves that it's the photographer, not the camera that makes the difference. One of the things that makes a JamCam interesting (and useful for beginning photographers) is that you can often find them on sale for prices under $30. The day I got mine, the store was charging half that much for a USB cable like the one that comes packed-in with the camera.
The ConceptI turned to the JamCam as an experimental infrared camera when I discovered that my brand new Canon Powershot G2 was awful as an IR camera. Canon has placed a very efficient hot mirror (infrared blocking filter) somewhere in the optical path. As far as the G2 is concerned, there's very little difference between a IR filter and a lens cap. Frustrated by the G2, I set about seeing if I could turn the JamCam into a usable IR camera. With conventional SLR cameras there are filter threads on the front of the lens, and the usual technique for IR filters is to thread a #87 or #89 glass filter onto the front of the lens. Rummaging through the back of my equipment drawer I found an old #89 filter and a little yellow envelope containing a #87c Kodak gelatin sheet filter. The gelatin filter was at least five years old, and I noted with amusement that the price on the sticker was higher than what I had paid for the JamCam. The JamCam has no threads to which a filter could be attached, so I made some test shots just holding the glass filter in front of the camera, and some more with a scrap of the #87c gelatin filter held over the lens with a bit of Scotch tape at the edges. To my delight, in full daylight the camera produced usable IR pictures. The camera appears either to be moderately sensitive to infrared or at least to have enough exposure control to come back with a picture when you cover the lens with an IR filter and press the shutter button. The next step was to figure out how to jury-rig a filter holder onto the front of the JamCam.
Adding a Filter HolderAfter considering a bunch of alternatives, it appeared that using the gelatin filter made more sense than trying to mount some sort of threaded ring to the front of the camera. Being a tinkerer by nature, I was aching for an excuse to disassemble the camera anyway, just to see what was inside. I pulled out my set of jeweler's screwdrivers and opened the JamCam. I convinced myself that it was safe to use a #56 drill to make a couple of small holes up to about 1/4 inch deep in the black plastic ring that surrounds the lens. With a pair of wire cutters I fashioned a filter holder out of a paper clip, and slipped it into the two holes. This lets me slide an inch-square piece of the gelatin filter in and out so I can mix infrared and normal shots at will.
Zero Cost IR FiltersBut the real breakthrough came later that evening when I was browsing Professor Andrew Davidhazy's web pages. Prof. Davidhazy is Professor of Imaging and Photographic Technology at RIT, the Rochester Institute of Technology. He also knows more about photography just about all of us here a photoSIG put together. Hidden amongst the photographic treasure trove that is his web site, Professor Davidhazy posted a page titled Making an Improvised infrared Transmitting Filter. There he asserts that a sheet of unexposed but developed E6 slide film approximates the spectral transmission of a #87 filter, and he presents spectral response plots of real filters and E6 film to back up his assertion.
Comparing ResultsHow does it work? See for yourself. Here are sample shots taken with the JamCam without a filter, and with three different infrared filters; a #89 glass filter, a #87c gelatin filter, and a scrap of unexposed but developed slide film. In my opinion, the no-cost IR filter performed as well as either of the commercial filters.
The color and tonality of the shot through the no-cost E6 filter appears closest to that of the #89 filter. This may vary depending on the particular E6 film chosen. If you experiment with different films as IR filters, be sure to write an article for PhotoSIG and tell us all about your results.
PostscriptI didn't use a tripod to take those test shots, so each is from a slightly different position. If you are into 3D imaging, you've probably already noticed that the two shots in the center make a nice stereo pair.... but that's whole different article.If you found this article useful or interesting, please take a moment to rate it. Thank you.
Additional JamCam IR ShotsKelley Park, San Jose
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