In article
(most deleted, about Rollei 35's)
>The versions with the F/2.8 Sonnar are reputed to be
>significantly better optically in the corners of the frame.
They are, but I wound up buying back my Rollei 35 with the Xenar
(similar to the Zeiss Tessar) and selling the Sonnar version - slides just looked better with the 4-element lens, regardless of the tests.
Hope this helps.