Just looked at an early M6 C/W 50 F2 summicron - very used but recent CLA and cheapish price ( private sale) The lens has the black paint/coating flaked off but of more concern was the coupling ring on the lens had a slight depression around the area of the infinity mark. Not being that familiar with the Leica lenses yet is this normal or should the surface be perfectly flat all round. To me it looks like wear as the lens has been focused here so many times that the roller cam on the body has worn this point down -or is this 'ground' in during manufacturing to align the lens focusing on individual lenses?

-- John Griffin (john@griffinphoto.u-net.com), March 01, 2002

Answers

The second--the cam is custom ground in the manufacturing process, only on the area that will touch the cam follower in the camera. Usually there's a visible ridge where this grinding ends, just beyond infinity.

-- Michael Darnton (mdarnton@hotmail.com), March 01, 2002.

The final grinding of the lens cam is done by hand.

-- John Collier (jbcollier@powersurfr.com), March 02, 2002.