Comments about Voigtlander Voigtlander M-Bayonet Adapter for 15mm, 28mm, 90mm Leica L Screw Mount lenses:

This is an adaptor ring for attaching Leica screw mount (so-called L mount) lenses to Leica M mount bodies. The 28/90 mm version of the adaptor ring activates the 28/90 mm bright frame in the camera's range finder. (On my Leica M4, the whole finder corresponds to 28 mm, so there is no bright finder for that focal length.)

Other manufacturers offer adaptors having the same function. The obvious difference is cost -- the expensive ones cost 5 times that of the cheapest. The qualitative difference is subtle. Once you hold the adaptor in your hand, observe it closely, and attach it to your lens first and then to the camera, you will see that the better adaptors are built much more precisely and carefully. The result is aesthetically pleasing.

In order to attach the mount as close to the lens as possible (flush to the lens mount base), Cosina Voigtlander made their adaptor ring thin yet strong. The ring can be attached by hand, but for firmly attaching and detaching, you use the 3 notches around the ring's circumference. The plastic lens cap and body cap that come with adaptor (nice accessories I didn't expect) have 3 male molded notches that you can use to tighten and loosen the ring.

Comments about Voigtlander Voigtlander M-Bayonet Adapter for 15mm, 28mm, 90mm Leica L Screw Mount lenses:

Well made from good quality stock. Lens is positioned correctly for correct focus.