Mamiya's Sekor Fish-Eye SX 14mm f/3.5 — a scarce Japanese M42 full-frame fisheye prime.
The Mamiya-Sekor Fish-Eye SX 14mm f/3.5 is a Japanese full-frame fisheye prime made in M42 mount by Mamiya. Part of the later SX screw-mount system, it was the specialist fisheye of the Mamiya range, giving the strong curved perspective characteristic of fisheye optics.
This is a manual-focus M42 screw-mount lens with a 14mm focal length and a maximum aperture of f/3.5, designed as a full-frame fisheye rather than a rectilinear wide. Focus and aperture are set by hand, and fisheyes of this type incorporate built-in filters. Detailed element figures are not asserted here beyond the verified focal length and aperture.
As a fisheye the 14mm produces a wide, curved field of view that bends straight lines away from the centre, used creatively for landscapes, interiors and dramatic perspectives. The very deep depth of field makes focus largely uncritical. It is a specialist optic chosen for its distinctive look rather than conventional wide work.
Used copies are scarce and collectible owing to the specialist fisheye design and lower production. Inspect the curved front element for scratches, haze and fungus, verify the aperture and any filter mechanism work, and check the mount and focus. Note the SX coupling when adapting. Verify the M42 mount. An M42 adapter allows fisheye use on mirrorless.