Talking rubbish again. I see on the 40d you can also control the thingies Bwana mentioned.Not sure about the 1d, but with the 40d (and 350d), you can control the flash level to + or - 2 stops from the camera. It's much easier to do that on the flash itself (unless you have a 420ex which has a mimimum of controls). I don't recall any other controllability (is that a word?) from the camera.