I use a MF 28mmF/2 lens with the focus taped to infinity so that I can't change focus accidently in the dark. I also set the exposure to iso 400 - 800 depending on how dark the sky is. I use the this formula to determine what the shutter speed should be, 600/focal length of the lens, this is the longest shutter speed that you can use and not get any star trails. Last night (3:00am this morning) I use iso 800, 20 second shutter speed and F/2 aperture to photograph the Meteor Shower with the camera set to manual.
