The Minolta MC W.Rokkor-SI 1:2.5 f=28mm is a wide-angle prime lens for Minolta SLR cameras with SR-mount (MC, MD).
This lens came in three versions:
MC-I version from 1969 - 1970 (photo 6)
MC-II version from 1970 - 1973 (photo 1 - 5), with "hill and valley" focus ring (in German called: "Berg und Tal")
MC-X version from 1973 - 1975 (photo 7), with rubber focus ring
All three versions have an identical lens design with one radioactive Thorium glass. So sometimes the glases can be a bit yellowish.
Links to online resources:
Posted by: Andreas Lindemann Date of publication: 06.04.2018