50mm f1.7 SMC-M.

I got 50mm f1.7 M a few days ago, for under a fiver. Full of fungus. It was very easy to strip down and clean. I have been taking some test shots with it, today.

It is an amazingly sharp lens! I would say sharper than my A 50 F1.7, which baffles me, as I thought that they were optically identical.
I really do think it is the sharpest 50, I have ever used.
My intention was to clean and sell it, but having been wowed by It's quality, I may well keep it.

Perhaps you need to strip and clean the SMCP-A 50mm now then.