The Mamyia Sekor E 1.7/50mm (as well as it later sibling, the E 1.7/50mm S) is a small, lightweight and low-price nomal lens for the Mamiya Z series of SLRs. Production started around 1980, and it was sold in large quanties bundled to the ZE, ZE-2 and ZM cameras (the latter usually with the "S" version). The lens is a typical "improved double gauss" Planar type with six lenses in five elements. 

Given how cheap the Mamiya ZE was sold in its time, the Sekor 1.7/50mm is rather well made. It's barel is mainly made from metal, but as with other Sekor E primes the focusing ring as well as the aperture ring are made from polycarbonate. Since there's no separate rube focusing grip, the lens feels platicky. Most lenses these days have their lube tried ou, and re-lubrication is needed if the lens should be used regularly. Doing so is pretty easy as the lens is build modularly.

The lens performs surprisingly well. Wide open - as usula with fast vintag normal lenses - there's a slightly reduced contrast even in the image center. Resolution drops visibly towards the borders, and there's some color fringing.

Stopping down to f4 results in nearly in perfect image quality (on 24 MP FF), only the extreme corners gain a liitle bit when stoppng down to f5.6. Image quality then remains constant up to f11. There are very little CAs visible (if any at all), and at these aperture settings the lens is really shining.

Since the lens was manufactured in large quantities it is availble for very low prices these days (around CHF 10.-- to CHF 20.-- including a ZE / ZEE-2 body). The lens can be used on mirrorless camera using adapters manufactured e. g. by Fotodiox. Since the adapter does include a mechamism for aperture control it is more expensive than adapters for other brands.

		MAMIYA SEKOR E 50mm 1:1.7              (6 lenses / 5 elements)
		MAMIYA SEKOR E 50mm 1:1.7 S          ( lenses /  elements)