If you can get a Canon 50mm f1.8 for 100 Euro or less in nice condition, this is really a very good lens which compares favorably with the early summicrons, not to mention the excellent price-perfomance ratio. Compared to the early Summicrons it has more contrast (and perceived sharpness) wide open, much higher flare resistance in a smaller and lighter package. Donwisdes are higher distortion and the odd filter size (40mm). Then there is the limited minimum focus distance (1 m) (same as the early Summicrons but less than the later ones starting with version III (1969-79), which feature 0.7m). Build quality of the Canon is not Leitz level, but quite good IMO. Make sure you get a clean copy, Some of the Canon lenses tend to build up haze. This is based on my personal experience with a later 50mm f1.8 (black/chrome barrel), I do not own or cannot comment on the earlier serenar (all chrome barrel) lenses.