Schneider-Kreuznach — 135mm f/4 vintage telephoto lens for Exakta and M42 SLR mounts
The Tele-Xenar 135mm f/4 was Schneider-Kreuznach's compact telephoto for 35mm single-lens-reflex cameras, part of a Tele-Xenar range that spanned from short teles up to long-focus barrel lenses. It reached SLR owners through Exakta and M42 screw-mount fittings.
It uses a classic telephoto layout intended to keep the lens body shorter than its focal length would otherwise require, with a manual preset or automatic diaphragm depending on production batch. Precise element count and filter size are not confirmed from a verified source here.
As a modest-speed 135mm design it delivers adequate subject separation for the era rather than pronounced background blur, with contrast and colour rendering typical of Schneider's coated glass from the period, better suited to daylight use than low light.
It turns up occasionally on the UK used market, generally at low prices reflecting its status as a secondary system lens. Check the aperture ring clicks and diaphragm actuation on the mount, and inspect for the haze common to uncoated or single-coated tele designs.