Which Pentax 200 2.8? I think there may be a few.
The 6x7 seems to do well. I have a 165 2.8 6 x 7 which is sharp wide open and no false colour.
Marc on this site has posted numerous Pentax 200mm astro shots. Perhaps look for one of them to get the exact 200mm model he used. I am not sure now if it was the 6 7 version or another one.
Greg.
|