Shooting in IR in 5 easy steps
1. Select an appropriate camera
I used Canon PowerShot A80, when I incidentally discovered that its IR blocking filter passes quite some IR to the CCD.
Check if your camera “sees” IR with a TV remote control. It should look like this:
2. Get an IR-passing, visible-light-blocking filter
You can buy quite some of them (Cokin, Hoya), but I chose another way and made one myself from overexposed & developed film. I cut two tiny pieces from the end of some of my old filmstrips (there always is some overexposed slack at the end).
I used two layers of film (just to make it completely block visible light) and made an improvised IR-passing lens-cap for my camera.
Another test with the remote control showed that overexposed and developed film is virtually transparent for IR.
3. Get outside
Sun is probably the strongest IR illuminator you can afford. Sunlight decreases the exposure times and your pictures end up less grainy.
4. Take pictures
It needs some experimenting to get the optimal exposure and focusing. At least in my case, where my DIY filter probably blocked some parts of IR spectrum as well – the image on the LCD was very dark and I had to focus manually by feel.
All pictures have a strong violet tone, like this one:
With some postprocessing (Auto Levels in Photoshop), you can make it look like this: