The Mamyia Sekor E 2.8/28mm is the younger cousin of the Sekor CS 2.8/28mm, with whom it shares its optical formula. Both lenses have a rather sophisticated [8/7] lens layout - many of the contemporary 2.8/28mm had only five lenses. Notheworthy exceptions were the Nikkor Ai 2.8/28mm and the Minolta MD-I/-III 2.8/28mm with seven lenses, and the AiS Nikkor and the Leica R with eight lenses.

Both the CS and the E / EF 2.8/28mm lenses are tiny and lightweight (165 g) despite of their metal barrel. On 24 MP fullframe cameras the Mamiya Sekor 2.8/28mm performs as good as the Minolta MD 2.8/28mm [7/7] or the Nikkor Ai 2.8/28mm (7 L). Even the Zeiss Distagon CY 2.8/28mm is not much better.The Mamiya has slightly more lateral CAs

Adaption of the E and EF lenses to Sony E-mount cameras is easy; commercially available adaters e. g. from Fotodiox allow seting of the aperture which originally was controlled by the Mamiya Z-series cameras themselves (there's no direct link between aperture ring and aperture mechanism on the lens!).

Back in the mid 1980s I've been using this lens extensively for landscape photography, always with excellent results. It has replaced the slower Mamiya Sekor E 3.5/28mm, which was even lighter, but not as good as the faster 2.8/28mm.

MAMIYA SEKOR E 28mm 1:2.8                  (8 lenses / 7 elements)

Below there are 100% corner crops from the JPGs out of the 24 MP Sony A7RII.