I am currently testing different adapters on my Sony NEX 5. One no name (was crap and I sent it immediatly back), one Fotodiox and 2x Kipon Contax -G adapters. There is a new version out of the Kipon adapter. The new one has no spaces between the riffles anymore. Compare the pictures. Although all the adapters are looking almost identical, they are not. The focusing does not get smoothy with some. I did not try yet the adapter from metabones. I find it too expensive. And I read on the internet, that the focusing ring is too big and disturbs the fingers while holding the NEX.