Having a good set of Leica M lenses (21 2.8 asph/28 2 asph/35 2 asph/50 2/50 1 noctilux/90 2 apo asph), I can say the 50mm summicron is the best lens I own. I use it as an all around lens, shoot 70% of time with this lens, in every light condition, at every shutter speed, every aperture and it performs greately evry time. If the lens doesn't produces sharp images or images without a good contrast IMO it's a problem of the single lens in question. Send it to assistance. Taking apart the Noctilux, wich is another kind of lens with specifical purposes, the 50mm summicron is one of the best lens Leica produces.