Infrared: CCD and CMOS

[samirkharusi]

It does not seem to matter whether the sensor is CMOS or CCD. What does matter is the Infra Red cutoff filter that has been built into the specific camera model. These sensors are generally very sensitive to IR. For normal photography IR is simply light pollution that would mess up colour balance. The ideal IR cutoff filter would pass through 100% of visible wavelengths and 0% of IR, without a transition slope. It appears that the more recent DSLRs approach this ideal better than the earlier models. The older digicams had long slopes between visible and IR wavelengths. You just have to check the specific model you own. The further from ideal the IR cutoff filter is (ie the worse it is in doing its assigned job) the shorter the exposure you will need when you use an IR filter over your camera lens (misnomer, since these filter out visible light and pass IR!). Here's an example taken with a Hoya R72 filter on a D30. The L channel is the IR image, the Hue and Saturation came from a photo without the filter, just experimenting:
http://image.pbase.com/u18/samirkharusi/up....r72natural.jpg
Note that the sky and sea go very dark while foliage goes bright, as you expect it to do in IR pics.

[Masatoshi]

I've successfully used a Canon S40 for infrared. It was easy to test its sensitivity by aiming an infrared remote control at the lens and seeing what was invisible to my eye light up on the camera screen when I pushed the remote's buttons. The S40 is a CCD camera. Does anyone have experience with infrared on CMOS cameras, such as the Canon SLRs? Are CMOS chips similarly sensitive? Can anyone out there point a remote at their lens and tell me what happens? Thanks!

[BJL]

FYI, one or two recent Sony digicam's have an IR "night photography" mode, in which the internal IR filter is flipped out of the way; I hope other makers follow suit, since from what samirkharusi says, the sensors in digital cameras are inherently very well suited to IR work. (And that is the first nice thing I have ever said about a digicam from would-be digicam monopolist Sony!)