Image courtesy: Photozone.
Let’s have some break from rumors! Klaus from Photozone (Click here) tested the Zeiss Biogon 28mm manual lens on the NEX-5: “The Zeiss Biogon T* 28mm f/2.8 may be a star on Leica M film cameras but it struggles somewhat with the Sony sensor in the NEX-5. The image quality is pretty much breathtaking in the image center but the border performance is actually much less impressive and in fact quite soft at large aperture settings. The border quality improves to very good levels (just) when stopping down though.”
The Zeiss Biogon is an M-mount lens and you will need an M to E mount adapter to use it on a NEX (Click here to see these adapters on eBay). The lens itself costs around 800-1000 Euro/Dollars (Click here to see the lenses on eBay).
UPDATE: And today Photozone (Click here) tested the 35mm Biogon: “The Zeiss C Biogon T* 35mm f/2.8 is supposed to deliver great images on film but it doesn’t really harmonize well with the Sony sensor of the NEX-5. The center image quality is simply great even at max. aperture but the border resolution is somewhat disappointing especially considering the moderate base aperture. The borders are still good (just) at f/2.8 and increase steadily till f/8 towards very good (just) results.” The lens has the same price as the before mentioned 28mm biogon (Click here to see the 35mm BIogon auctions on eBay).