I've got a really old Pentax 17mm fisheye which I don't use as much as I should. It's nice but very limited, there's no/negligible coatings on the glass so if there's any light source in frame it flares like crazy. The glass is also mildly radioactive which sets off airport scanners whenever I go away with it. If I was looking for another for 35mm/full frame I'd try and get one of the Zenit ones with a slight lens hood and some coatings.
I've got a really old Pentax 17mm fisheye which I don't use as much as I should. It's nice but very limited, there's no/negligible coatings on the glass so if there's any light source in frame it flares like crazy. The glass is also mildly radioactive which sets off airport scanners whenever I go away with it. If I was looking for another for 35mm/full frame I'd try and get one of the Zenit ones with a slight lens hood and some coatings.