Archived posting to the Leica Users Group, 1996/06/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hallo Hans, lets try to explain difficuilt things in my very restricted English. > I will not argue aginst your findings, but here is what the 1989 Leica > Catalogue said: > Leica: General Catalogue for Photographic Dealers (1989), page 11-9: > "...These lenses can be mounted on the Leica M, but do not provide precise > copupling with the rangefinder. .....we do not recommend the use of Cl > lences on Leica M cameras." > > What does "precise coupling with the rangefinder" mean, really? If Garys > conclusion is correct, focusing an Elmar C 90/4,0 should be less demanding > for the M-rangefinder than a Summicron 90/2,0, and yet, Leica do not > recommend it?!? When You look into a Leica bayonet, you see a little wheel on a lever in it, just on top, beneath the rangefinder. It is this wheel, which turnes the prism of the rangefinder around. When you turn the meter-ring of the lens out, putting it to a near destination, the wheel comes out, at infinity the lever with the wheel is put inside. I think the way length of the lever between infinity and 70 cm correllates with the way of a 50 mm-lens. Wide-angle-lenses have shorter ways, tele-lenses have longer. So then Leitz-people had to translate the individual adjustment-way of each lens into the constant way of the rangefinder-lever. In the M-series they did it with an additional ring, whose way is translated from the ring you draw around focusing and which presses the little wheel always exactly from the front. In the CL-Lenses they drive the wheel with the inner side of the ring you use for focusing. Of course this inner side can not be plain, it has to be curved. So the little wheel is not pressed exactly from the front like in the M-lenses. It is pressed from the side, so its going not so easy as it could be. But I don`t think, that this simplified construction must cause worse accuracy. The Leica manual, you are quoting from, with is from the good old times of Leitz Wetzlar. Please compare with my minilux: Manual focus on this camera has only 10 steps between 70 cm and infinity, and the Leica people tell me in the manual that this is enough ;-) Regards Reinhard