If money is an object, as it is in my case, I picked up a 50 Summar for less than $100 US, have not yet tried it and seen results. I am not
proficient at looking for scratches, haze, fungus or other ailments common to all lenses, so let's see how it turns out using a bargain bit of
glass. An even cheaper lens is the Industar 50 2.8, that I got on e**y for $19.00. Took it apart and fixed the aperture screw, old solid grease, and tightened all the tiny screws and it seems fine now, but like the Summar, results are still to come.
With hope,
Geoff