If anyone is still watching this thread, I read recently that many sensors have IR sensitivity to some degree as they come from the factory. The test is to set the camera for live view, if possible, and aim the business end of a TV remote at it and press a button. If the live view shows a little flash, you're good to go, with the appropriate filter, of course. My Pentax K 5 shows as sensitive; I haven't tried it yet for shooting since I don't have an IR filter, yet.