The Schneider Xenar is a 4-element Tessar design camera lens. It isnít a good choice for enlarging as it isnít designed to produce a flat field of focus forward of the lens as an enlarger, process, or macro lens is.

I wonder if there are any other markings on the lens to possibly indicate that it was a variant designed for close-focusing flat-field copy work. The 4-element 50/4 and 75/4 EL Nikkors are examples of Tessar type enlarging lenses that work very well. So the idea that you might have a variant for flat-field close-up work is at least plausible, but I donít know.

A Schneider Componon is a 6-element double Gauss flat-field enlarging lens and that makes it a good process or macro lens as well.

All lenses must produce a flat field at the plane of the film, but only enlarger, process, and macro lenses are designed to produced a flat field forward of the lens. In contrast, most camera lenses produce a slightly curved field of focus (bellied out like the front glass) forward of the lens.

Process cameras were used in a variety of ways, not always in photographing strictly flat originals. In one of my reference books a large horizontal process camera is shown photographing a large 3-dimensional piece of artwork well forward of the camera. In such an application the lens neednít be the usual flat-field lens usually employed on a process camera.

We can only speculate on how the lens youíve shown was employed. The fact that itís mounted in a barrel, and not in a shutter, indicates that it was most likely used on a process camera or enlarger. The exposure was most often flash or tungsten photo-floodlights on a digital timer in a large darkroom. If the lens is a standard-design Xenar, then itís unlikely that it was used for enlarging.