Collapsible Summicron 50mm f2. This example features thorium glass and is commonly known as the Radioactive Summicron. Its radiation level has been checked using a simple dosimeter. Serial number in the 1,040,000 range, manufactured in 1952. Distance scale in feet. Leitz product code SOOIC.

As is typical of thorium Summicrons, the glass has developed a pronounced yellow tint. This particular example has an especially deep yellow coloration, comparable to that of the early under-one-million serial number examples.

Measurements with a dosimeter also showed a rather high radiation level, even compared with the many thorium Summicrons we have handled over the years. Quite a potent one, indeed! (LOL)

The yellowing may slightly enhance contrast when shooting black-and-white film. This is also a fascinating lens for those curious to compare its rendering with that of later Summicrons made with conventional optical glass.

This lens was previously sold by our shop and has now returned to us after being carefully used by its previous owner. It remains in the same excellent condition as when we last sold it.

Showing relatively little signs of use, this lens is in very good cosmetic condition for a thorium Summicron. There are some scuffs around the front edge of the barrel from attaching and removing the hood, but no noticeable scratches or dents. Wear on the collapsible section is also minimal.

A full overhaul, including focus adjustment, was carried out in 2026. Thanks to the careful servicing, both the aperture ring and helicoid remain exceptionally smooth, with a pleasantly refined feel. Rangefinder coupling is also spot-on.

There are very faint cleaning marks on the front element and some coating deterioration on the rear element, but these should have virtually no effect on actual photographs. Many thorium Summicrons suffer from considerable deterioration of the optical elements, but this example has glass in remarkably good condition. A rare find.

Comes with the original Leitz front cap.