Steinheil's telephoto Culminar — the 135mm f/4.5 in Leica Thread Mount.
The Steinheil Culminar 135mm f/4.5 in Leica Thread Mount is a vintage German telephoto from Steinheil Munchen, made in screw mount for L39 rangefinder bodies. It is a classic post-war long lens from the Culminar line, used on screw-mount and adapted rangefinder cameras.
It is a manual-focus rangefinder-coupled lens with a 135mm focal length and a maximum aperture of f/4.5. As a telephoto it couples to the rangefinder for focusing, though 135mm is at the long end of practical rangefinder use; the moderate aperture keeps the lens reasonably compact.
The 135mm focal length reaches distant subjects and compresses perspective, suiting portraits, detail work and some landscape use. The Culminar renders cleanly, with sharpness improving on stopping down, and the modest f/4.5 aperture keeps depth of field manageable at this focal length.
As a vintage German optic, used copies should be checked for haze, fungus, cleaning marks, coating wear and separation, along with focus feel and aperture oil. Accurate rangefinder focusing is harder at 135mm, so verify coupling and infinity, or plan to use it on mirrorless with magnified focus. It adapts to Leica M with an LTM-to-M ring and to mirrorless cameras via an adapter.