How can I take infrared photos with my 40d?

Question

Not permanently!!

Answer 1

There is a problem.  There is a "hot mirror" mounted in front of the cameras sensor.  IR cannot be seen by your cameras sensor while it is still in place.

You can make pseudo IR shots using a 25a red filter on the lens and then converting the resulting image file to a black and white image in photoshop, -100 saturation and then using the level tool to set the black threshold, white threshold and moving the mid-tone adjustment until you have the image quality you want.

Answer 2

I have a Hoya IR filter. I put my 40D on a tripod, switch the lens to manual focus, set the correct focus, then put the IR filter on the lens. Getting the right exposure is a bit of a challenge, but try a few different settings. In some of the shots I noticed a bit of a hot spot, but others looked fine.

Then post process according to taste.