Are the Retina Xenar 50 3.5 and 50 2.8 lenses the same optical designs?

[Steve M.]

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!

 

[JPD]

Yes, both Xenars are Tessar-type lenses with four elements in three groups.