Schneider-Kreuznach — 35mm f/4 manual shift lens for architecture, sold across many SLR mounts
The PA-Curtagon 35mm f/4 was Schneider-Kreuznach's perspective-control shift lens for 35mm SLRs, letting photographers correct converging verticals in architectural shots without a view camera. It predated dedicated shift lenses from most Japanese SLR makers and was fitted across many bayonet and screw mounts, including a version supplied for the Rollei SL35 system as the PC-Curtagon.
It offers roughly 11mm of parallel shift via a geared knob and scale, with a manual preset aperture ring since the shift mechanism precludes automatic diaphragm coupling. Precise element count, weight and filter thread are not confirmed from a verified source here.
As a shift-only design rather than tilt-shift, it corrects vertical convergence while keeping the plane of focus parallel to the film, useful for building facades and interiors; image quality holds up reasonably well across the shift range for a lens of this age.
Copies surface occasionally on the UK used market, appealing mainly to architectural photographers and collectors of vintage manual glass. Check the shift mechanism moves smoothly through its full travel without binding, and confirm the preset aperture ring clicks accurately.