Design of the Mamiya 2.8/80 lens for the C330
I always believed that the standard lens for the Mamiya TLR was a run of the mill planar, but looking at the manual it's supposed to be a 5 elements in 3 groups lens. The lens schematics resemble neither a Planar, Sonnar, Heliar or Ernostar design so what it is based on?
Kind of looks like it might have been derived from a Tessar. Just a guess though.
Sekor 2.8/80 is the most similar to ... Leica Elmarit 2.8/90 for Leica.
The next three lenses seem to belong to a group known as Modified Cook Triplets. In
the 1930s, Max Berek of Leitz, designed several lenses for use in Leica cameras, based
on the Cook Triplet. The Sekor 80mm, figure 5, is one of these. The similarity to the
“Elmarit”, shown in figure 6, is immediately evident. The “Elmarit” is a relatively new
design, dating from 1958. The Sekor 80mm is considered to be the “normal” lens for
the Mamiya 6x6 format and operates with excellent aberration correction and
resolution. Mine seems to be a little subject to flare, which can easily be minimized by
use of the proper hood.
Source: Mamiya TLR Interchangeable Lenses by Dr. Robert Smith