Originally Posted by Alberti
Looking at it again,
maybe the difference between the two adapters is:
- the "simple" one has a tab, this is used to focus.
- The complex one, there the lens itself is rotated and this will be transferred via the cam to the body helicoid.
Wrong. The "simple" ("dedicated") one has only the internal bayonet - hence it will only fit the 50mm lens. The more complex regular one has both the internal and external bayonet, and will fit 50mm lenses as well as wides and teles.