It sounds weird but it appears the Samyang 35mm F1.4 at about AUD$535 is better than the Zeiss 35mm F1.4 especially for astrophotography.
http://www.dxomark.com/index.php/New...ut-to-the-test
I don't think those magenta/purple halos in the Zeiss wide open would look too good in a widefield DSLR Milky Way shot!
They also have recently put out a 24mm F1.4 with not a lot of reviews available but perhaps this may be more useful for astro than
35mm for APS and full frame cameras.
Greg.