I don't have too many East German or FSU lenses in Exakta or M42 mounts. I did have a 50/2 Zeiss Pancolar zebra lens in Exakta mount and it was optically good if a little balky mechanically. That was traded with my VX 500. Somewhere I have a 35mm Enna Lithagon in M42 mount. I don't remember whether it's an f/3.5 or an f/2.8 lens. It seems to have yellowed cement between the elements. My best old German lenses in M42 mount are a 30/3.5 Meyer Lydith and a 35/3.5 Noflexar. Both are excellent. I wouldn't expect any of the older German M42 lenses to be better than a late model 55/1.8 Super Takumar. The coating is the only important thing to consider. The 55/1.8 S-M C-T and 55/1.8 SMC lenses are quite good and I wouldn't expect many other lenses of that speed or focal length range to be much better. When the 55/1.8 SMC was changed to K mount for the KX, K2 and KM cameras it only stayed in production for a short time before it was replaced by the 50/1.7 M lens. I still prefer the 55/1.8 SMC Pentax to the later 50/1.7 M. The latest lens in that line that I have is the 50/1.7 SMC Pentax-F. I use it as a portrait lens on my K-x but it's also very good on film cameras and has more modern coating that the 50/1.7 M.
I don't think the Tessar design was ever patented.This from an advertisement of March 1941 reproduced in Classic Camera magazine no 6 1990 p26:
"An Englishman, H L Aldis designed and caused to be produced before 1900,an anastigmat lens later to be developed into the famous Aldis f/4.5.In doing so he had anticipated the Zeiss Tessar Patent of 1902.
When the Aldis f/4.5 appeared,Zeiss.....demanded that all stocks be destroyed and an end put to the business.
They confidently applied for an interim injunction and in reply H L Aldis put in his affidavit particulars of his work prior to 1900.
...the judge had to be informed by Zeiss's counsel that their clients case had collapsed.It could not be disputed that the Tessar patent was void,having been anticipated by Aldis."
I have found good Tessars to have more contrast than the good 1.8 Super-Takumars.
I was thinking the exact same thing. Tessars are not so sharp in the corners at wider apertures, but they improve considerably when stopped down. But contrast using a clean, coated Tessar will be very good.
Isn't Nikon's 45mm f2.8 pancake lens for the FM3a basically a modern, coated Tessar?
Henry A Certified Dinosaur
Nikons F, F2, D700, Leica M3, & Kiev 4a