Archived posting to the Leica Users Group, 1996/04/04[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]
So, are the optical elements in all current M lenses made with glass containing Lanthanum (or other REE)? Is the incorporation of REE now common among modern lens manufacturers or does Leica still lead in formulating better glass and/or using it more extensively? >The first "glass explosion" occurred in the late 1800's when Ernst Abbe >convinced Otto Schott to dedicate his glass research to the development and >production of high-refractive index optical glasses. The second occurs in >the late 1940's when Leica developed the use of rare-earth glasses, >especially Lanthanum mixtures. As Laney wrote in his Leica Collectors Guide >(p. 123): > > The decision of Leitz to set up their own glass research > laboratory after the war, probably to reduce their dependence > on Schott who naturally favoured their parent, Zeiss, was > the step that revolutionized Leitz lenses in time for the > M3. Its first major achievement was in making practical, > highly refractive glasses with low dispersion by incorporation >of lanthanum oxide in the melt... The first fruit of this > investment was spectacular -- the 50mm f/2 Summicron of 1953, > which set entirely new standards for 35mm camera lenses. > >And, later (p. 132): > > Summicron 50mm f/2: Clearly derived from the Summitar, but > with a superior performance brought about by new glasses giving > the designer greater freedom... Three of the elements were made > from glass developed by Leitz. > >The prototype Summicron -- the prized "Star Summitar" -- dates from early 1952. > >Other authorities discussing these developments include Keller and Rogliatti. > >Leitz pioneered the use of computers in lens design (1949) and the use of >rare-earth glasses. The Wetzlar, and now Solms, insistence on being at the >cutting edge of technology is quite, quite impressive! > >Marc > >firstname.lastname@example.org FAX: +540/343-7315 >Cha robh bas fir gun ghras fir!