Mamiya Sekor E 4/300mm - an extremely rare lens for sure (mine has SN 10067 and therefore seems to be the 67th lens manufactured). It's the first time I've seen it for sale here in Switzerland, and I was lucky to get it.

According to the data published by Mamiya it seems to have the same optical formula as the earlier (and more common) Sekor CS 4/300mm. Preliminary tests suggest that the
performance indeed is identical. While the Sekor E 4/300mm on 24 MP FF is very sharp (even wide open and in the corners), it has quite pronounced lateral CAs - but that's a problem with nearly all "non-ED/AD/ULD/Fluorite" 300mm lenses of course!

At a mere 740 g (measured) the Sekor E 4/300 is probably the lightest of its class (the earlier Sekor CS was 785 g). Compare this to the Nikkor-H Auto 4.5/300 at 1070g, the Canon nFD 4/300 at 950 g or the Minolta MC-X 4.5/300 at 1180 g ... only the Minölta MD 4.5/300 is nearly as lightweight: 775 g, but only f4.5 of course.

Despite the lightweight construction, the lens barrel is very well made and entirely out of metal (apart from the aperture ring, but that's really a minor detail). While the Sekor E 4/300mm is pretty large, it feels well balanced on the Mamiya ZM at least (the ZM has a nice small grip which facilitates handling), On the Mamiya ZE-X, Mamiyas most advanced 35mm SLR, the lens feels nearly as good, especially when the winder is mounted. Only the ZE/ZE-2 bodies are a bit tricky since neither of them has a built in grip.

The biggest disadvantage of the Mamiya Sekor CS and E 4/300mm lenses of course is their MFD: At 5.0 m its MFD is even worse than the MC-X (4.5m) or the Nikkor-H (4.0m). Of course the MD and the nFD are much better (3.0 m) since they are IF designs.

MAMIYA SEKOR E 300mm 1:4                  (5 lenses / 4 elements)

The Sekor E 4/300mm is one of the several Sekor E lenses I tried to buy just after the collapse of the Mamiya / Osawa / ... empire; back in 1984. The Swiss representative of Mamiya was selling many of the less common Sekor E lenses for a fraction of their original price, and being 15 yo their offers were quite tempting. While the E 2.8/28, the EF 1.4/50, and the E 4/200 were still available when I heard about it, they had sold their last E 4/300 just one day ago. Of course I was deeply disappointed, but alas ... here we go.
After nearly fourty years the lens has arrived, finally ...