Leica's R shift lens — the manual-focus PA-Curtagon-R 35mm f/4 for architectural perspective control.
The Leica PA-Curtagon-R 35mm f/4 is a perspective-control shift lens for the Leica R reflex system, based on the Schneider Curtagon design. The PA designation marks its perspective-adjusting shift function, which lets the photographer correct converging verticals without tilting the camera. It was the R system's dedicated shift lens for architectural work.
This is a manual-focus Leica R lens with a 35mm focal length and a maximum aperture of f/4, fitted with a shift mechanism for perspective control. The lens can be shifted off-axis to keep the image plane parallel to the subject, correcting converging lines. Buyers should confirm the shift and locking mechanism operate smoothly and verify the cam configuration on the specific example.
The shift function makes this a specialist tool for architecture and interiors, where keeping verticals straight is important and tilting the camera would cause them to converge. It also has uses in product and landscape work where controlled perspective helps. At f/4 it is a deliberate, tripod-friendly lens rather than a fast handheld optic.
On the used market the PA-Curtagon-R is an uncommon specialist R lens valued by architectural photographers. Test the shift movement and its lock for smooth, secure operation, check for internal haze and fungus, and confirm the aperture is clean and dry. Verify the cam setup for metering behaviour on your R body, noting that shift lenses can affect metering when shifted; a Leica R adapter allows mirrorless use where the shift function remains available.