Collapsible Summicron 50mm f2. Leitz product code SOOIC. Serial number in the 1.09 million range, manufactured in 1953. Distance scale in feet. Filter size E39.
This is an early model featuring thorium glass, commonly known as the “radioactive Summicron.” To increase the refractive index, glass containing the radioactive material thorium was used. Confirmed with a Geiger counter. This particular example shows relatively low readings, and the characteristic yellowing of thorium glass is minimal. Color cast in actual shooting is expected to be slight.
In monochrome photography, it delivers slightly enhanced contrast, with the characteristic sharp focus plane of the Summicron, rich bokeh, and a strong sense of depth.
A lens that invites exploration, especially when compared with later generations of the Summicron.

Shows some minor signs of use such as light scuffs, and there is a repaired impact mark on the edge of the filter rim. The repair has been carefully carried out, and filters and hoods can be attached without any issues.
Fully overhauled in March 2026. Both the aperture ring and helicoid operate very smoothly, providing a pleasant handling experience. Rangefinder coupling is spot on, and focus is accurate.
The glass shows a few faint cleaning marks, about two to three on both the front and rear elements. There is also very slight coating wear, and under strong LED light a faint haze-like appearance can be seen around the middle elements, but this was not noticeable in actual shooting.
The results from the test shots were excellent. Please refer to the sample gallery.
Original front and rear caps are included.