Mamiya's Sekor 55mm f/1.4 — a well-built Japanese M42 fast standard prime.
The Mamiya-Sekor 55mm f/1.4 is a Japanese fast standard prime made in M42 mount. Produced by Mamiya, which made M42 SLRs and lenses under the Sekor name, it was the fast normal lens of their screw-mount range, a well-built standard prime of the era.
This is a manual-focus M42 screw-mount lens with a 55mm focal length and a bright f/1.4 maximum aperture. Focus and aperture are set by hand on the barrel, with an automatic diaphragm. It is a solidly built all-metal fast standard prime. Detailed element figures are not asserted here beyond the verified focal length and aperture, following the accuracy standard.
The slightly-long 55mm with a fast f/1.4 aperture suits portraits, low-light and general work, giving shallow depth of field for subject isolation. Fast standards of this type render smoothly wide open with pleasant out-of-focus areas, firming up stopped down, giving the characterful look many seek from vintage fast fifties.
Used copies are moderately priced and less common than the Pentax and Soviet standards. Inspect for haze, fungus and cleaning marks, confirm the aperture blades are clean and oil-free, and check the aperture-ring and focus feel. Verify the M42 mount, as Mamiya also used other mounts. An M42 adapter makes it a characterful fast standard on mirrorless.