{"overview":"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.","market_narrative":"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.","buying_guide":"Inspect the front and rear groups for fungus and haze, since long RB67 lenses often sit unused for years; check the leaf shutter fires cleanly at every speed and that the aperture blades are dry and snappy with no oil. Look for coating scratches, edge separation, and confirm the focusing helicoid turns smoothly without grit, and verify the lens-to-body bayonet locks firmly without play.","specs":"Telephoto prime for the Mamiya RB67 system with a 250mm focal length and f\/4.5 maximum aperture, mounted in the standard RB67 bayonet with built-in leaf shutter.","faq":[{"q":"What is a Mamiya RB67 250mm f\/4.5 worth today?","a":"Based on UK auction hammer data, a working copy sells for around £30, though that figure comes from a single 2025 sale and is not a full price range."},{"q":"How much does a Mamiya RB67 250mm f\/4.5 sell for at auction?","a":"The one verified UK saleroom result we hold is £30, so current value at hammer level is in that low double-digit region for an average example excluding commissions."},{"q":"Is the RB67 250mm f\/4.5 a good portrait lens?","a":"On 6x7 it gives a moderate telephoto field of view well suited to head-and-shoulders portraits, and the f\/4.5 aperture combined with the large format yields shallow depth of field at close distances."}],"confidence":35,"reasoning":"Specs and variant data are empty and only one verified sale exists, so pricing confidence is limited to a single data point."}