Archived posting to the Leica Users Group, 1992/04/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]In Gunther Osterloh's "Leica M: the Advanced School of Photography" there are several drawings showing the evolution of Leitz 50mm lens development over the years. One drawing shows an early 1950s version of the Summicron with 7 elements all having indices of refraction in the 1.6 - 1.7 range. The drawing for the redesigned version of the late 1960s has 6 elements (I think) but indices of refraction above 1.7. What does this all mean? The text doesn't elaborate but better performance is implied along with smaller size as a feature. Laney's book "Choosing and Using Leica Lenses" shows contrast/edge-spread graphs for a 50mm Summicron versus a 50mm Summitar (again, my memory may be failing me). In general, the Summicron really shows its stuff at the edges of the frame. - Kevin (kbb0@harvey.gte.com)