The Mamiya Sekor 250mm f/4.5 is a manual-focus medium telephoto lens for the RB67 6x7 system, designed in the 1970s era for portrait and short-tele work on rotating-back RB67 bodies. It uses the standard RB67 bayonet mount with an in-lens leaf shutter, intended for studio and location professionals shooting 6x7 transparencies and negatives.

At UK auction the RB67 250mm f/4.5 is an inexpensive piece of glass: the only verified hammer result in our records is £30 in May 2025, which gives a single-point reference rather than a range. As of 2026, that wholesale saleroom level reflects soft demand for longer RB67 optics, and clean later "C" multi-coated examples typically sell for more than uncoated early copies when buyers can compare them side by side.