Great for mechanical (non-electrical) lens!
There is confusion on what these mechanical adapters do. I use the Canon eos to Nex (sony e) on on A7RII A7RIII and A9. You must set in the camera menu to"shoot with no lens attached" ! If a traditional electronic lens like the Canon EOS lens is attached, no electrical communication will happen between the camera and lens. (camera will think "no lens attached"). You will have no f stop, auto-focus, vibration reduction.If you use some of the excellent "all mechanical" Chinese or vintage lens with mechanical f-stop and focus rings, you use the rings on the lens to set f-stop and focus. This is an all mechanical solution that works great on so many of the excellent mechanical macro and wide angle lens. I use with Venus 12mm lens EOS mount and various vintage Leica R lens that have been converted to EOS mounts. All these EOS mount mechanical lens work great on the Sony E mount!!