Archived posting to the Leica Users Group, 2003/04/27
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Well Greg, heh, heh, heh, I'm glad you asked, you do have your seatbelt fastened and your choice beverage at hand don't you. Goood, well let's enter into the halls of the double gauss design as interpreted by Leica. Circa 1953 you might have been able to buy either one of the first design lenses. With the advent of high refractive glass in the late forties, unfortunately made allegedly with Thorium, the double gauss design could finally come to some kind of parity with the Sonnar design. So, we had a few years of a modified Summitar with an * after the name, Summitar*. After some tweaking this lens was released as the first generation Summicron. This lens has a center that is very sharp without defining really fine detail. It is also somewhat flare prone especially at the wider apertures. By 5.6 this is a really outstanding lens although contrast levels never reach current standards. Generally acknowledged around serial #1,000,000 a non radioactive glass was available from Schott so Leica slightly recomputed the lens to take advantage of this home grown glass. At least from my sample, this newer lens is just not quite as crisp, or as sharp. Nothing major, just not quite as good. The optical design consist of a rather large front pair of elements with a very small air lens separating the two elements. The next pair of cemented elements is heavily positive. After the aperture is a cemented doublet concave, concave, slightly convex, more convex. The last element is rather large. Three of the elements are LaK9. You didn't ask, but along around 1955-57 Leica redesigned the lens again, adding another high refractive element as the rear element, and enlarging the air lens in the first group. Also, the rear group was enlarged to accommodate the larger throat of the M series. Properly cleaned and assembled, this lens is the overall king of Summicrons, especially when shooting B&W. It does not quite have the contrast of the latest one, but if you can adjust your developing of printing, this is one wonderful lens. - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html