zhangyue wrote: I am really surprised for MP50 infinity results though.
A big plus for both cron are size, they are about 1/2 to 2/3 of volume and weight.
Thanks. Indeed, both Crons appear compact next to their Zeiss equivalents. Cron-R 50 is especially convenient. It's not that much larger than my Voigtländer 40 mm F 2.0 Ultron SLII + its attached dome hood.
As for MP50 performance at infinity, well, in its defence the distance to provided 100% crop location was nearly 3 km, which may be too much for a macro lens. I think Summicron-R 50 is simply a great lens by comparison to MP 50 and overall.