Digital Rebel for infrared

[jamisan]

I have the Canon Rebel XS. Would like to get an IR filter,can I use this camera for IR photography?

[Bob Atkins]

You can, but it's not very sensitive. For all the EOS DSLRs you need exposures of several seconds under most conditions and that's with ISO set high and a fairly fast aperture). See section #5 of http://www.bobatkins.com/photography/tutorials/digital_filters.html.

I have an example with the XT here - http://www.bobatkins.com/photography/digital/eos_digital_rebel_xt_review2.html - and I'm sure the XS will be similar

The filter you will need is a Hoya R72

[jamisan]

OK I bought the Hoya R72,played with it a little. The post processing is going to take some work and experimentation.
What filter would I need to let some visible light through?

[Bob Atkins]

By definition, an IR filter is one which blocks visible light. The more visible light you let though, the weaker the "IR effect" will be. The R72 acually allows some very deep red to pass though. It's really the "weakest" IR filter, but if you use anything stronger you won't get any image at all with most DSLRs.

The next filter down towards the visible would be a very deep red/IR filter like the B+W 092. It should give you something of an "IR" look, but it probably won't be as strong an effect as with the R72. Exposure times should be a little shorter though.

[jamisan]

So the only "visible" light an IR filter lets through is red. I guess what Im asking is, is it possible to take "color" photos with an IR filter,or is the only way to get a "color" photo is through post processing.

[klindup]

You can buy modified DSLRs that have the internal IR filter removed.  They are used primarily for astrophotography where people are interested in one particular wavelength at the red end of the spectrum.  A modified 40D body in the UK costs about £1,300.  The company doing the modifications is called Hutech.  For normal use it is necessary to fit an IR filter to the lens (I think it fits at the rear).

[Bob Atkins]

Infrared has no color, since by definition you can't see it! If you can see it, it's not IR. A monochome (B&W) representation is the best you can do.

All colors you see in IR images are artificial, the result of a small amount of visible light "leaking" into the IR image or are due to the some residual IR response in the Red, Green and Blue pixels which the camera then interprets as "colors". The faint colors can sometimes be amplifed in post processing.

As pointed out above, you can get much better IR respose (including false color response) with a modified camera, but they are not cheap. You can get a conventional camera modified for around $500 or so if you want to dedicate one to IR work and there are several companies that will do that work. The camera can still be used for "conventional" photography, but youy'd need an IR blocking filter on the front of the lens. Those filters are not cheap either.