I've taken a shot of the South African stars and the Milky Way with my 50D and 24-105L. The details are as follow: f 7.1, ISO 100, 24mm and shutter set to BULB at 2414 sec open. It took the same tame for the camera to process the photo and the result was very disappointing, a lot of black dots in the shot. See 100% crop of the photo. When I did this last with my 300D, the photo was much better. O-yes, the camera was mounted to a tripod and I did forget to put the IS off.