Actually, the 35/2 Biogon is a very good lens in its own right. Quite sharp and with a color rendition that matches my other Zeiss M-mount glass (50/2, 50/1.5, 21/2.8) pretty well. I wonder if the difference in cost isn't from having an OEM manufacturer (Cosina) do the actual manufacturing as opposed to workers in Germany. Whatever the reason, the image quality of the Zeiss glass seems comparable to Leica. It was ever thus: they are great rivals in terms of optics. As for long term durability of the lenses, we will see. In terms of M-mount photography I think there are more and higher-quality lenses available for M-mount cameras than there ever have been before. Having to choose among them is a nice problem to have.
Ben Marks