Leitz 50mm f2 Summicron LTM Lens Condition: Mint-
Leitz 50mm f2 Summicron - Thorium/Lanthanum
(10% discount when bought with a Leica IIIg from FilmFurbish - refunded after checkout)
About this lens:
Probably the holy grail for LTM Mount Cameras. The Thorium/Lanthanum glass Summicron delivers corner to corner sharpness. These are highly sought after by collectors. They give a vintage cinematic colour cast and are extremely sought after for black and white photographers in particular. They are great for colour too, like shooting with a golden hour filter and create wonderfully warm colour film images.
It has very mildly radioactive glass (not dangerously so) and is from a small batch produced by Leica for its specific qualities of high refraction.
A beautiful lens in excellent condition, having been stripped and serviced by the Leica specialist who services all my Leica and Leitz lenses. The lens is very clean with no fungus or haze, and the blades free of oil which is exceptionally rare for these lenses, and none of the usual dust you would expect for a lens of this age. Comes with a metal Leica lens cap and plastic body cap.
These early Summicron's are the most collectible, this one is no exception.
Possibly the most desirable lens for the Leica LTM mount cameras producing sharp and characterful images.
10 blade lens with 7 elements.
Serial Number: 1193302
Year of Manufacture: 1953
About the Leica 50mm f2 Summicron with Thorium/Lanthanum Glass
By the late 1940s, the management at Leica knew they needed to come up with a superlative successor to the well-respected 50mm f/2 Summitar that had been designed by the legendary Max Berek in 1937 and had been in production since 1939.
By that time, they were diligently working on a stunning new Leica camera that was to become the landmark Leica M3 of 1954, and their goal was to grace it with the finest, most advanced 50mm f/2 lens the world had ever seen.
The assignment fell to Gustav Kleinberg and Otto Zimmermann, two of the most brilliant optical designers at E. Leitz Wetzlar and close associates of Berek, who passed away in October 1949. To create what became the Summicron, a 7-element, a 4-group masterpiece with elements having shallower curves than those in the Summitar, they needed to use glass that provided a very high refractive index (light-bending power), along with very low dispersion (the differences in light-bending angles for various wavelengths of light.)
The classic measure of the optical dispersion of a glass is its Abbe number; the higher the number, the narrower the dispersion spectrum, and the easier it is to control chromatic aberrations, etc.
At the time, the only way to achieve glass that provided a very high refractive index and a high Abbe number was to incorporate a “rare earth,” thorium oxide or lanthanum oxide, into the glass itself. Both materials emit radiation that can be measured with a Geiger counter, but thorium is significantly more radioactive than lanthanum because a much larger percentage of it consists of an unstable isotope.
The eventual plan was to use a special Krown Lanthanum glass (later licensed to Schott Glass Works as LaK9) that was formulated by Broemer and Meinart in Wetzlar’s renowned glass division. But LaK9 glass wasn’t available until late 1952, and even then only in limited quantities.
The interim solution: the very first batch of “stealth” 50mm f/2 Leitz Summicrons, identifiable by having a star (asterisk) engraved after the word Summitar on their identification rings, and early examples of the correctly labeled collapsible Summicron dating from late 1951 to 1952, used thorium glass supplied by Chance Brothers & Co, Ltd. of West Smethwick, England!
For the record, thorium (aka Torio) glass was used for elements 1, 3, 6, and 7.
These lenses are the unique and collectible “radioactive Summicrons” of lore and legend that tend to acquire a yellowish-brownish cast over time that can be eliminated by extended exposure to UV (that is, sunlight.)
According to those who’ve shot with a wider variety of 50mm f/2 Summicrons than I, the earliest Summicrons and the very rare Star Summitar are quite good but not stupendous in terms of image quality. Later iterations of the classic 7-element 50mm Summicron (serial numbers 993,000-1.030,000) that employ lanthanum (LaK9) glass provide noticeably better imaging performance, especially wide open. However, this and subsequent improvements were the results of tweaks in the optical design, not the type of glass used. The great Walter Mandler, then chief optical designer at Leitz, was responsible for many of these optical upgrades, including the design of the 6-element, 5-group, and 6-element 4-group 50mm f/2 Summicrons, both of which incorporated other types of lanthanum glass.