Mamiya's RB67 portrait-normal — the leaf-shutter Sekor C 127mm f/3.8 for 6x7.
The Mamiya Sekor C 127mm f/3.8 is a short-normal to short-telephoto lens for the Mamiya RB67 medium-format system, from the C-series line. It was another lens frequently bundled with RB67 bodies and often used as a portrait-leaning normal on the 6x7 format. It sits just above the 90mm standard lens in reach.
This is a manual-focus lens native to the Mamiya RB67 bayonet mount, with a focal length of 127mm and a maximum aperture of f/3.8. It contains a built-in leaf shutter like all RB67 optics, with aperture set on the barrel and focusing by the camera bellows. The design covers the full 6x7 image circle.
At 127mm on 6x7 the angle of view corresponds to roughly a 62mm lens on 35mm, a slightly long normal that flatters portraits with mild compression. The leaf shutter allows flash sync at all speeds, useful in the studio, and the lens delivers even sharpness across the frame when stopped down. It is a popular choice for head-and-shoulders portraiture on the format.
The 127mm f/3.8 is common on the used market thanks to its frequent inclusion in RB67 kits. Test the leaf shutter at all speeds for clean, prompt firing and watch for stickiness. Inspect the glass for haze and fungus, confirm the aperture blades are dry and close cleanly, and verify the bayonet and shutter-cocking coupling engage correctly before buying.