I have a
Vivitar 24mm f/2.8 with 'A" aperture. My copy has a mount label of
PK/A-R but it does not have the Ricoh pin in the mount.
I believe mine is Cosina but I am yet not quite sure. I am quite happy with my copy of Vivitar 24mm f/2.8 from Cosina. It is not in solid construction but all plastic but that makes it a lighter lens well suited for street shooting. It does quite well in close up. Though not advertised as close up lens, I think it get close to 1:4, maybe 1:6 to 1:4 but I have not checked in detail. I have been using it for
street shooting, traveling and
night shooting and traveling. It is a charmer in my book. I then look for the Cosina/Vivitar 28mm f/2.8 thinking about similar quality but I found them very different. Maybe I luck out with my copy of 24mm.
Thanks,
Hin