Sirs,
The original qestion was whether to buy a 50mm C\Y Zeiss. No info on whether that was for film or digital use.
The answer is that for normal printouts A4, A3 ?? whether on an RTS, S2, ST...or a digital Canon, a properly focussed Zeiss will be splendid.
I do not photograph test charts or brick walls, and do not usually make larger printouts, but i do occasionally make blowups from parts of the frame. I find find that even my occasionally derided 25mm, my 50mm, my 60mm macro and my zeiss Vario Sonnar zoom are all perfectly adequate.
Since I also happen to have a stack of ancient Leica R optics, which I use with film as well as digital, I can state with confidence that for my kind of untutored snaps, the Zeiss products are not at all inferior to its other top end competitors.
p.