Archived posting to the Leica Users Group, 2002/09/13
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The original production Leica I (A) also has the tab on its non-interchangable lens. The lock is on the body. The Leica 0, nullserie, and the UR (Barnack's prototype) Leica have a tab but apparently no lock. So the feature goes all the way back. As with the Summar there is not much else to hold on to on those lenses. My source is "Leica, The First Fifty Years" by Rogliatti. Mike D SthRosner@aol.com wrote: > Hello Rei: > > The likelihood is that the infinity lock, that is, the knob which acts as a > lock, was a carryforward from the 50/2 Summar lens of the 1930's. This lens > did not have a grooved or serrated edge to use to grasp the lens mount and > use it as a focussing ring. One focussed it only by using the knob. The > infinity lock was just a means of locating the lens helicoids at their > innermost focussing limit. > > I don't remember for certain whether or not the 50/2 Summitar that intervened > between the Summar and the first Rigid 50/2 Summicron has the grooves; my > recollection is that rudimentary grooves were introduced with the Summitar to > facilitate focussing without resort to the knob. And by the time we get to > the Rigid Summicron, it has not only know and grooves but scallops cut into > the focussing ring. > > Just a guess but I imagine that by the 50's when the Summitar was introduced, > photographers had become so used to using the knob for focussing that Leitz > retained it. It could not be employed on the Dual-range of course because of > the complicated mechanical construction of the focussing mount of that lens. > And the knob disappeared completely on 50mm lenses in 1969 with the > introduction of the first six-glass 50/2 Summicron. > > Seth LaK 9 > -- > To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html > > - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html