Pentax's medium-format shift lens — the SMC Pentax 6x7 75mm f/4.5 Shift for architecture on 6x7.
The SMC Pentax 6x7 75mm f/4.5 Shift is a perspective-control lens for the Pentax 6x7 medium-format system, from the SMC Pentax 6x7 generation of the line. Its shift mechanism lets the lens move relative to the film plane, correcting converging verticals on the large 6x7 negative, a tool aimed squarely at architecture.
This is a manual-focus lens for the Pentax 67 bayonet mount, covering the 6x7 cm frame. It has a fixed 75mm focal length and a maximum aperture of f/4.5. The shift function relies on an oversized image circle so the frame can be moved off-centre, and the Super Multi Coating denoted by the SMC prefix helps hold contrast across that wide covering circle.
By shifting the lens up or down the photographer keeps the camera back parallel to a building and avoids the keystoning that comes from tilting the whole camera. This makes it a specialist tool for architecture and interiors on the 6x7 frame, and the large negative captures the detail these subjects demand.
On the used market this shift lens is a scarce and pricier specialist item bought by architectural and large-format-minded 6x7 shooters. Check that the shift and focus mechanisms move smoothly and lock properly, inspect for haze and fungus given the extra glass, and confirm dry aperture blades. It can be adapted to mirrorless through a Pentax 67 adapter.