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09-15-2010, 10:46 AM   #16
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QuoteOriginally posted by procyon Quote
Photoshops filter for converting colour images to black-and-white has a preset called "Infrared", which is just some combination of coefficients for different colours to give a "infrared-ish" look to the resultant B&W image. K20D very very likely does just that.
Exactly right. The digital 'IR' is more of a deeper Red. The Hot.Filter in front of the sensor cuts-off around 700nm and IR 'light' (EMF) just doesn't reach the sensor. You can't digitally emulate what isn't there.

I really can't imagine the camera really physically moving the IR-cut filter (that's the thing in front of sensor that gets rid of most of the infrared) aside from the sensor and later back.
That's exactly what Sony NightShot cams do. On my DSC-V1 is a switch -- flick it, and listen to the Hot.Filter being snapped out of the way! I use can 780nm, 900nm, 930nm and 1000nm filters handheld. Well, the 1000nm usually requires BRIGHT sunlight or some stabilization, but everything's quite visible in LiveView. Filtering the other end of the visible spectrum works well too, with Violet or Dark Blue filters passing only 'actinic' light to emulate early photo emulsions.

But virtually all dSLRs lack this capability. The exceptions: Fuji and Sigma make 'forensic' dSLRs with Nikon mounts. The Hot.Filters are easily removed and replaced with clear glass, or UV- or IR-pass filters, or any spectrum-slicing filters you want (but the whole set ain't cheap). IMHO anyone seriously into digital IR either needs to have surgery done on their dSLR to replace the Hot.Filter with optical glass, or obtain a forensic cam. Last time I looked, they weren't *too* expensive...

09-15-2010, 01:09 PM   #17
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I haven't tried IR all that much with my K20D - it was very nice and much quicker on the K100D, and pretty ordinary with the K10D. Nevertheless, this is one basic example of a monochrome IR result I got with the K20D in daylight. I'm yet to master IR post-processing so excuse the simplicity of the image:


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