Archived posting to the Leica Users Group, 1997/07/15
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Dear Fellow LUGnuts, Carl asked about the concave lens elements of the 35mm Asph Summilux lens. <snip>Is it really concave? I have never heard of such a thing. Although Leitz is certainly a trendsetter. <snip> Indeed this lens (like the 35 Asph Summicron) has both concave elements on the front end and the back end of the lens. The 28mm Elmarit has a plano front surface and convex back surface. I think Leitz/Leica is going through a period of new lens designs that hasn't occurred since Dr. Walter Mandler came up with a lot of the classical lens designs in Canada. The lenses that come to mind (and I am sure there are more - Marc help me out here) are the 180mm f 3.4 Apo telephoto lens and the 50mm f 1.0 Noctilux. It took a certain amount of imagination to come up with these lenses. Although Leitz has had computers and optical programs to optimize lens designs for many years, it still takes the imagination of a person to conceive of a new design concept. Then the computer can run the thousands of calculations to see if a lens could be built. The design may be too heavy, too expensive or just too difficult to build. Can you image Professor Max Berek having to design by hand the first 5cm f 3.5 Anastigmat lens for the earliest of Leicas? As part of my professional responsibilities, I prescribe single element lenses for my patients every day to optimze their vision. The highest index of refraction I can order is 1.66. I can order this with a multiple layer anti-reflection coating and UV blocker. Even though I have taken multiple courses in optics, it is hard to conceive how someone using hand caluculations could design the early lenses used by Leitz. The early limitations were more related to a lack of antireflective coatings so the lens designer was limited to minimal lens elements. Now there are catalogues of glass available for the optical designer. Leica is on a roll right now and I'm enjoying it. I wonder how long it will take due to low cost lens blank molding that all the M and R wide angle lenses include one or more aspheric lens elements and floating elements for a clearer flatter image field. Almost all the telephoto lenses of the R system are now Apochromatic. With lens prices being as high as what they are, its almost a give away when Leica prices the M6 at $1995. (I hope Leica doesn't read this). Having seen how Leica makes lenses in Solms, I don't see how they can make all that much money on each one. They were grinding lens elements one at a time instead of in batches. The reason I was told was consistency. I'll get off my soap box now. Respectfully, Richard - -------------------------------- Richard Clompus, OD West Chester, Pennsylvania, USA