The Sekor CS 2.8/135mm, again, is a extremely lightweight lens for its class. While most other CS lenses are on par with the corresponding lenses from the well known manufacturers (Canon, Minolta, Nikon, ...), the CS 2.8/135mm simply has too much lateral CAs. If the cromatic aberrations are corrected in post processing, its performance is absolutely OK, though. While Minolta in its well known MC/MD 2.8/135mm [4/4] did use a thick lens made from a heavy specialty glass (resulting in a lens weight of >500 g), Mamiya chose to stay light: Only thin lenses were used, probably made from lighter non-specialty glass. 



Mamiya CS 200mm f35 lens section Mamiya CS 135mmf28 MAMIYA SEKOR CS 135mm 1:2.8                 
(5 Linsen / 4 Glieder)