Leica's long Visoflex telephoto — the Telyt 400mm f/5, a reflex-housing screw-mount reach lens.
The Telyt 400mm f/5 is the long reflex telephoto of the pre-war Leica system, made from the mid-1930s to give the greatest reach in the range. Like the 200mm Telyt it is a Visoflex lens, using a reflex mirror housing rather than the rangefinder to focus and compose at this focal length on the screw-mount Leica.
This is a manual-focus Leica Thread Mount telephoto with a 400mm focal length and a maximum aperture of f/5. It is a reflex-housing lens and is not rangefinder-coupled; it is focused through the Visoflex mirror box. Because of its length it was often used with a shoulder stock or tripod, and the correct Visoflex housing and focusing mount must be present for it to work.
At 400mm this was the reach lens for distant wildlife, sport and nature work where nothing shorter would do, composed directly through the lens via the reflex housing. The f/5 aperture keeps the long barrel usable, and the long focal length demands firm support for sharp results.
This is uncommon collector equipment and values depend on a complete, matching Visoflex and mount system rather than the lens head alone. Inspect the large elements carefully for haze, cleaning marks and separation, check coating wear on coated examples, and confirm smooth focus and dry aperture blades. It adapts to Leica M via a 39-to-M adapter and to mirrorless with an L39 adapter, where reflex focusing maps naturally onto a live-view screen.