SnappyHappy wrote:
Stars begin to disk at speeds below 12 seconds for me. I have read resolution is a factor in determining minimum shutter speed. I recently posted a Milky Way shot using the npr rule which held my shutter speed to 10 seconds. I shot the attached photo with a Canon 5DSr with EF 24/1.4 @ 1.8 @ 8 seconds on a tripod. Lots of light pollution, I know, but note the nearer stars upper right of the Milky Way.
Nice photo! I think the star trails in it might be partly the lens or aperture. I always use at least 15 seconds and have never had star trails from it. I will have to look into it more.