On another IR point - if you take a photo with a dig camera (or even a film camera) using a R72 or similar, you end up with a very red image. See the example below.
This is as the R72 still lets through a lot of red light - the '72' is the cut-off point of 720 nm. You get a better 'raw' image if you use a R90 filter which cuts abover 900 nm.
You can partially correct by manually setting the white ballance - take a photo of a white sheet of paper (or grey card) and then use the image to do a white ballance.
But to fully correct it so that it closely approximates proper IR film such as Kodak HSIR ('High Speed [50 ASA] IR B&W) or Kodak Ektachrome IR, you need to Photoshop it. These films (do they still exist?) have different sensitivities to normal film - the B&W is actually sensitive from the UV to the IR, but at the IR end goes way past normal B&W film - see
http://www.kodak.com/global/en/profe...002_0333ac.gif
The colour IR film still have three layers - yellow, magenta and cyan - and is also sensative from UV to IR, but the red and cyan in particular are much more senstaive to IR than is normal film. Really, the three layers havebeen swapped around - the yellow is red - yellow - green sensitive, the red is yellow - orange - red sensitive and the cyan is red - IR sensitive. These then give the 'typical' IR photo when used with a R72 or R90 filter.
http://www.kodak.com/global/en/profe...009_0537ac.gif
To get similar results with dig, you need to invert the three colours and do a colour shift. There are a few Photoshop 'actions' that do this - a good one is David's from
http://khromagery.com.au/resources.html
Also have a look at
http://khromagery.com.au/digital_ir.html and scroll about 3/4 the way down - there is a shot of Melbourne with the various ways of processing. It goes from red to 'typical' IR colour film look - dark blue sky, red foliage etc, although these do vary quite a bit depending on the lighting conditions etc.
As I mentioned in a previous post, you can do all this with a non-converted camera and the R72 filter, but expect shutter speeds of 10 - 30 seconds in full sun.