Are the Retina Xenar 50 3.5 and 50 2.8 lenses the same optical designs?
I'm trying to figure out if these are essentially the same lenses except for the wide open apertures, or if they're different optical designs. All I can find so far is that the 50 2.8 is a Tessar design of 4 elements in 3 groups. Nada on the 50 2.8. Any ideas? Not sure who the Retina guru is here, but if anyone would care to venture a guess, thanks!