Carl Zeiss Jena MC Flektogon 20mm f/2.8, which was manufactured by Carl Zeiss Jena DDR up until early 90s, is one of few Eastern European lenses that seem to have achieved almost legendary status. Or so it seems based on discussions on various online photography forums. The lens replaced its older and slower variant - Flektogon 20mm f/4, and was available as auto and electric versions in M42 universal screw and later B (Practicar) mounts.

The optical construction of the lens consists of 9 elements in 8 groups. The front glass element is humongous - whopping 67mm, but the lens itself is relatively compact and light, measuring 70(D) x 55(L) mm (2.7 x 2.1 in) and weighing 350g (12.34oz). The inner cam of the lens extends slightly during focusing towards closeups, adding a few millimeters to the length. The build quality of the lens is pretty good as is the case with most Jena lenses - metal barrel, metal focusing and aperture rings, metal mount. The minimum focusing distance is 19cm (0.62ft), the minimum aperture is f/22. The lens accepts 67mm screw-in type filters. On APS-C type cameras with 1.6x crop factor, the field of view of the lens is equivalent to tat of a 32mm lens on a full-frame body.

As mentioned earlier, the MC Flektogon 20mm f/2.8 was discontinued after Eastern and Western Carl Zeiss companies merged. The lens can still be found on used markets like eBay, with good quality copies fetching over US$300 (as of August 2007). The lens is more common in Europe and less so in the US.


To test the lens on Canon EOS cameras, I used generic Fotodiox M42 to EOS adapter adapter without AF confirmation. I used camera in aperture priority mode, which along with the fully manual are the only two modes available to anyone using this type of an adapter.


Lens Composition 9 elements in 8 groups
Angular Field 93 degrees
Minimum Focus 19cm/0.62ft
Focusing Action MF
f-stop Scale f/2.8-f/22, manual
Filter Size 67mm
Lens Hood N/A
Weight 350g/12.34oz
Dimensions 70x55mm/2.7x2.1"
Lens Case N/A


Field Tests

The lens secured for testing had lens separation and showcased severe degradation in quality. Trying to secure another lens to perform the tests...


Vignetting @ f/2.8 - full frame vs 1.6x crop
Vignetting @ f/2.8 - full frame vs 1.6x crop


Lab Tests


Canon APS-C : Coming soon...


Canon FF: Coming soon...