Which 300mm f/2.8 manual lens
I'm looking for a 300mm f/2.8 manual lens to use on m4/3 for astrophotography. Auto focus has no use on stars. Oly has a ZD 300mm but the price is still prohibitive. There are other reasonably priced options such as Tamron, Tokina, Sigma, all of which I know very little about. The main requirements are sharpness, lack of CA, lack of coma, lack of dollars.
Does anyone have any ideas ?
Twin E-620/70-300mm/14-42mm/pinhole lens, plus 8mm FE, Tokina AT-X 90mm macro, and Zeiss 500/8 mirror.