Archived posting to the Leica Users Group, 1999/08/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]A few weeks ago there was some discussion of the use of radioactive thorium glass in an early version of the 50mm Collapsible Summicron and its prototype, the Summitar*. Are there any other Leitz lenses known to have incorporated radioactive glass? The only printed comment on this matter I've found is in Morgan's "Leica Manual", 14th edition (1961) where on page 67 the then recently introduced 35mm Summilux f/1.4 lens is described as "principally made up of Lanthanum rare-earth glasses ... and contain no radio-active thorium." - -- Pieter Bras