Vintage Leica Summicron 50mm in L39 screw mount (mislabelled Zeiss), adapts to M bodies via standard ring.
The Leica Summicron 50mm f/2 (L39) is the Leica Thread Mount version of the Summicron standard prime — the screw-mount Summicron produced for LTM cameras. Note: canonical name has erroneous 'Zeiss' prefix. Leica Thread Mount.
f/2 maximum aperture. 50mm focal length (full-frame standard prime). LTM (Leica Thread Mount, M39 screw). Manual focus. Leica Thread Mount.
The LTM Summicron 50mm f/2 is the screw-mount version — compatible with all Leica Thread Mount cameras and adapts to Leica M and modern mirrorless via M39 adapter. A classic Leitz standard prime in the historic screw mount.
On the used market the Leica Summicron 50mm L39 is a practical LTM standard prime. Condition checks: front element, LTM thread. Leica Thread Mount (M39/LTM).