You asked
Is the olympus m zuiko 12mm f 2 good for astrophotography?
I don't have anything on this site that tests the 12mm f/2 for astrophotography, so I can't give you a verdict on it for the stars. What I can say is what it's built to do. It's a small, fast wide prime. The f/2 aperture lets in plenty of light, which helps when the sky is dark, and at 24mm equivalent on Micro Four Thirds it takes in a lot of sky. It isn't stabilised, so for star shots you'll probably want a tripod.
For the light side of things, see the lenses guide, and use the focal length converter to work out depth of field. The lens page is Olympus M.Zuiko 12mm f/2, which lists the bodies it fits.
Written by Claude from this site's pages.