 Wayne Nolting |
IR Filters and theDigital Rebel I tried an experiment that I duplicated and documented the results on my camera club web site at www.centralctcameraclub.org which seems to disprove this theory. I then followed the suggestion from Tony Sweet from Better Photo to try a Hoya R72 and was able to record an image but it had a lot of red. I can remove the color and have it look like a real infrared. Since the Hoya R72 lets in too much red, what variant of IR filter should I lean towards? I am still experimenting had the camera on manual, "Bulb", exposed the image for about 123 seconds. AV was 11, and ISO 100. Any suggestions from anyone? Pictures are attached in support of my comments. They were taken through a window as a "rough test"
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Jon Close |
I believe the Canon DSLRs can record infrared. I have no idea what the camera shop employee meant by "hot mirror." It sounds like nonsense to me. There is a "low pass" or "anti-alias" filter over the sensor, but this is to smooth pixelation and lessen moire. I don't think it has any affect on sensitivity to IR or other wavelengths. The camera is going to record in color only. If you want a black & white IR photo you have to do it in editing. A Yahoo! search turned up this thread in another message board giving a routine for IR editing:
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Jon Close |
P.S. Visible red wavelengths extend to about 700nm. Infrared wavelengths are from about 700nm to 1200nm. The R72 passes wavelengths of 720nm and longer. You may get less red with Hoya's R90, which passes wavelengths longer than 900nm. I'm not sure, but I suspect that even with the R90 the DSLR will still capture these as deep red and you'll still need to edit the image to make it black & white.
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Mary Yetter |
Hi Wayne, I looked at your image on the camera club website. What steps did you take to remove the red from the original image? I just got a Hoya r72 fitler, and also have the digital Rebel, and I see exactly what you mean about too much red. I have adobe elements 3.0... Thanks for your help,
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Wayne Nolting |
Hi Mary: I used the Hoya R72 filter. I did discover that a well sunlit scene produces better details (stronger IR reflections) but can also wash out so I took images at 1 second increments. I then picked out the image which seemed to have the most amount of detail and removed the color with PSE2. Some minor brightness and contrast adjustments were applied to bring out detail and I also selected some areas that were too bright and adjusted the intensity. There are 2 IR images on my gallery: the "Land of Souls" which was taken in a historic cemetery in Hartford, CT, and "Lost in Time" which is an abandoned house I found In Granby, CT. I applied the same adjustments to this second image and added a light blue tint with PSE2.
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Mary Yetter |
Wayne, thanks so much for your speedy response.. Once the sun comes out here, in Missoula, I will be able to give it a whirl.. Thanks again!
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Lori Carpenter |
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