Mamiya's updated RB67 wide — the leaf-shutter K/L 75mm f/3.5 with improved coatings.
The Mamiya Sekor K/L 75mm f/3.5 is a wide-angle lens for the Mamiya RB67 medium-format system, part of the later K/L generation introduced around 1990. The K/L line brought updated optical designs and improved coatings to the RB67, and remained compatible with the RZ67 via adapter. On the 6x7 frame the 75mm gives a moderately wide view.
This is a manual-focus lens native to the Mamiya RB67 bayonet mount, with a focal length of 75mm and a maximum aperture of f/3.5. Like all RB67 optics it has a built-in leaf shutter, and the aperture is set on the barrel while focusing is handled by the camera's bellows. The K/L design was intended to improve on the earlier C-series wide-angles.
At 75mm on 6x7 the field of view is close to a 37mm lens on 35mm, a moderate wide-angle that avoids the more extreme perspective of shorter lenses. The updated K/L coatings help control flare and improve contrast over the older designs. The leaf shutter permits flash sync throughout the speed range, making it well suited to studio and location work.
The K/L 75mm f/3.5 is a later, higher-specification RB67 lens and generally commands more than the older C-series wide-angles. Test the leaf shutter across all speeds for clean, prompt firing, and check 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.