The Canon FD 400mm f/4.5 is a manual-focus super-telephoto prime for Canon's FD mount, the breech-lock and later bayonet system Canon used between 1971 and 1987. It was aimed at sports, wildlife and aviation photographers who needed reach on a 35mm SLR body.

At UK auction in the run-up to 2026, hammer prices for this lens have ranged from £90 to £188, with the two recorded sales averaging around £139 — wholesale saleroom levels rather than dealer retail. Clean, fungus-free copies with smooth focus tend to sell for the upper end of that band, while examples with cosmetic or optical faults make up what the cheaper lots are worth.