The 50/2 is rubbish. Just rubbish. It makes a decent body cap.
(My 1st post

Great images! I also enjoy the ML 55mm/2.8, as well as an ML 28/2.8, ML 50mm/1.4, ML 50mm/1.7, ML 50mm/2, ML 35-70/3.5, ML 135/2.8 C. Regarding the ML 50mm/2, I agree that something must be really wrong with your example. I can't think of any vintage 50mm/2 that exceeds its performance, despite its plasticity and compactness. Not even Summicron-R 50mm, V1 or V2, according to my testing. That means I can risk carrying a cheap lens into the rough and tumble of life without being afraid of scratching or denting a $400 lens.
Since I have (like many others here) an overflow of around-50mm lenses, and I'll be selling most soon, any tips for comparing the usual suspects would be appreciated. Besides Summicron, I can compare with:
Nikkor 50mm/2 pre-AI
Nikkor 50mm/1.8 AI
Nikkor 50mm/1.8 AIS snubnose
Nikon Series-E 50mm/1.8
Nikkor 55mm/3.5 Macro pre-AI
Canon FDn 50mm/1.4
Canon FDn 50mm/1.8
Canon FD 50mm/1.8 silvernose
Minolta MD Rokkor (various) 50mm or 55mm/1.7
Konica AR 50mm/1.7
Fujinon 55mm/1.8 EBC
Chinon 50mm/1.7 and 1.9
Zeiss-Opton Contax Sonnar 50mm/2
Schneider 50mm/1.9
Rodenstock 50mm/1.9
Schneider Xenar 50mm/2.8
Rodenstock Ysarex 50mm/2.8
Olympus OM 50mm/1.8
Yashica DX 50mm/1.7
Autorevuenon 55mm/1.4
Auto Reflex 55mm/1.4
Yashica DSB 50mm/1.9
Yashica DS-M 50mm/1.7
Pentacon auto multi coating 50mm/1.8 (my example seems amazingly sharp)
Is using quality-printed test charts the best way to test lenses?