Schneider-Kreuznach Xenar — classic 135mm f/4.5 Tessar-type lens for 4x5in press and view cameras
The Xenar 135mm f/4.5 belongs to Schneider-Kreuznach's long-running Xenar line, a Tessar-formula family the company began producing after the original Zeiss patent lapsed in 1919. This focal length was a common standard lens on 4x5in press and folding cameras through the mid-20th century.
Optically it follows the four-element, three-group Tessar arrangement typical of the Xenar range, prized for compact size and low cost relative to complex symmetrical designs. It was supplied mounted in shutters such as Compur or Alphax on view and press cameras, with no bayonet of its own.
Wide open it is soft-edged by modern standards, sharpening noticeably by f/8-f/11, which suits the small-aperture, tripod-based shooting typical of large-format work. Its modest speed and simple build keep it light and cheap next to faster Xenotar or wide-coverage Symmar options of the era.
These lenses turn up regularly on press and folding cameras being parted out for large-format use, often in shutters needing service. Check shutter speeds fire accurately, look for haze or separation between elements, and confirm the lens board or barrel threading matches the intended shutter.