The Summicron 50mm Lens by Harold M. Merklinger as published in Shutterbug, June 1994.

The Leitz 50 mm f/2 Summicron set a new standard for normal lenses when it was first introduced about 1953. A few prototypes were actually engraved Summitar*. This new lens had two particular features which distinguished it from its predecessors. It was the first “high speed” lens that equaled the performance of the 50/3.5 Elmar at any given f-stop. Thus the 35 mm photographer could choose a single normal lens without sacrificing either quality or speed. He could have both. And second, the Summicron was designed to have uniform image quality across the format, even at the larger apertures. Earlier lenses, and the lenses of other manufacturers, were designed for sharp, contrasty results in the very center, but image quality deteriorated towards the edges. 

The original 50 mm Summicron was produced in a collapsible mount, much like the Summitar and Summar that preceded it, and like it’s sibling 50/3.5 Elmar. The higher speed 50/1.5 Summarit was always in a rigid mount. In about 1956 a rigid version of the 50/2 Summicron for M-series cameras appeared with little explanation. A special version of the rigid lens, the Dual-Range Summicron for the M-3, did feature provisions for close focusing, however. It was not ’till 1960 or so that the rigid lens became available in screw mount—just as production of screw-mount Leicas was drawing to a close. Any number of references will tell us that the collapsible and rigid versions of the Summicron are optically identical. This information is erroneous; these two versions of the 50/2 Summicron are different designs. 

As the accompanying photograph will show, the rigid version of the lens is longer. The optics are set farther from the film and the lens mount than is the case for the collapsible version. The front element and the rear element are both set farther forward. This does not mean the focal length is different, however. The two lenses are simply different optical designs. Additional evidence may be seen in the photograph. The depth of field scales are identical, but the mark for infra-red focusing moves from the f/2 mark on the earlier lens, to roughly half-way between the f/4 and the f/5.6 marks on the later lens. 

In my view, the rigid Summicron represents as great a milestone in lens design as does the collapsible Summicron. The collapsible Summicron becomes somewhat lack-luster at apertures larger than f/4. The rigid Summicron, on the other hand, is fully usable at it’s maximum aperture. Images taken at f/2, even in the close-up range, are stunning in sharpness and contrast. The f/2 aperture finally became a true working aperture, not a low light emergency back-up. The rigid design also re-established the Summicron as the best normal lens available. Lenses of f/2 and f/1.4 from the Japanese competition noticeably surpassed the collapsible Summicron in the center of the image field—as for that matter did the Summitar, though over a very small angle only. I still rely on the original rigid Summicron whenever I seek the ultimate in 50 mm lens performance. This forty year old design is still among the very best! © Harold M. Merklinger,