I bought the Fotodiox Canon FD to Sony NEX Adapter for the tripod connection. A heavy or medium weight lens should not possible be mounted on a tripod or Focusing the camera thread. Without tripod mount there are good adapter for 1/3 of the price. In my case, I wanted to attach a FD 100mm macro lens. The lens (old "Chrome Ring" series) is not even particularly difficult with about 700 g. When I mounted the adapter with this lens to the tripod socket of the sliding plate, with the NEX 6 at the other end, the lenses immediately turned down. The arm with the tripod connector wobbles now only loosely around, taking up space and is completely useless.
Luckily, you can still use the part as a "normal" adapter, but goes also, as I said, with much less expensive adapters.