Mamiya's RB67 macro — the leaf-shutter Sekor C 140mm f/4.5 for 6x7 close-up work.
The Mamiya Sekor C 140mm f/4.5 Macro is a close-focusing lens for the Mamiya RB67 medium-format system, from the mid-1970s C-series. It was designed for close-up and reproduction work on the 6x7 format, taking advantage of the RB67's bellows for extended focusing range. It doubles as a short-telephoto for general shooting.
This is a manual-focus lens native to the Mamiya RB67 bayonet mount, with a focal length of 140mm and a maximum aperture of f/4.5. It carries a built-in leaf shutter, with the aperture set on the barrel and focusing driven by the camera bellows, which extends further for macro use. The optical formula was corrected for close-range flat-field performance across the 6x7 frame.
The combination of the 140mm focal length and the RB67's bellows draw allows high reproduction ratios for detailed close-up work. The macro correction holds sharpness across the large frame at short distances, and at normal ranges it serves as a capable short telephoto. The leaf shutter also permits flash sync at all speeds, useful for controlled close-up lighting.
The 140mm f/4.5 Macro is a specialist lens that appears less often than the standard RB67 optics. Test the leaf shutter across all speeds for clean firing, and check the glass carefully 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.