i have had great results with Nikon D3 and D3s using Nikon 14-24 wide open at infinity (pre-test infinity before it is totally dark) I auto focus at 20mm and carefully change to M on lens. Then place a small piece of tape on lens to prevent changing focus distance. Shutter speed below 30 seconds is critical for star points. (not star lines) Adjust ISO to obtain the settings. Use histogram, LCD in dark will look too bright and can fool you in believing there is adequate exposure. Try for a center histogram minimum. Finally, turn on Noise reduction settings in camera. This will double exposure time from say 28 seconds to approximately 60 seconds before image appears on LCD. Tripod is mandatory otherwise enjoy the show, just do not shoot same. Good Luck!