Aus Jena Flektogon 2.8/20mm

Flektogon 2.8/20mm bought (new) for 1995f on december 29th, 1989.

Carl Zeiss Jena,, Aus Jena, the name has changed, maybe some trouble with the "other" Carl Zeiss, the one which makes lenses for Hasselblad or Rollei?
I only found the Mir 20M from USSR two years later, so waiting for that...
It's not a "fisheye", it's a true wide angle lens, that is to say that the distortions are minimal. The optical quality is excellent.