08-13-2016, 03:36 PM
I don't know much about astrophotography. I tried this morning between 2 and 4 a.m. and found times between 6 and 10 secs wide open and between 400 and 1600 ISO sufficient. But I guess, the "wow" milky way shots are done by exposure stacking and at shorter times. To me, the "smear" looks more a result of earth rotation than of optical flaw.
And in the corners of the 20/1.4 Sigma it's coma, but in each corner equally and always pointing rectangular to the center, so I don't think it's because of decenterring. It's just because these lenses are usually not made to be best at infinity wide open, from center to corner. Some do have the butterfly appearance, but then, when I see our light pollution, I don't think it's worth to see how bad my other f/1.4 lenses are.
But no matter how bad those lenses are for astrophotography: Getting up at this time in the night is not my cup of tea anyway and still I enjoyed a lot the comets. I think I saw a dozen.
And in the corners of the 20/1.4 Sigma it's coma, but in each corner equally and always pointing rectangular to the center, so I don't think it's because of decenterring. It's just because these lenses are usually not made to be best at infinity wide open, from center to corner. Some do have the butterfly appearance, but then, when I see our light pollution, I don't think it's worth to see how bad my other f/1.4 lenses are.
But no matter how bad those lenses are for astrophotography: Getting up at this time in the night is not my cup of tea anyway and still I enjoyed a lot the comets. I think I saw a dozen.