I have a few M42 lenses (e.g. Carl Zeiss Tessar 50/2.8, Pentacon 135/2.8) that I'd like to use on a NEX. Using M42 lenses on my Canon DLSR I've noticed that quality between various adaptors varies a lot. To a certain extent it even depends on the used lens. Does anyone here have any experience with M42 to E-mount adapters (maybe even with these lenses)?