The Cosina 40mm f/2.5 is a compact wide-standard prime lens from the Japanese maker known for producing affordable manual-focus optics across multiple SLR mounts. Its slightly wider-than-normal focal length and moderately fast f/2.5 aperture made it a low-cost alternative to the standard 50mm kit lens, suited to general photography and travel use on 35mm SLR bodies.

At UK auction in recent years the Cosina 40mm f/2.5 has traded at modest, entry-level money: a single recorded hammer result from March 2023 sold for £38, which sets the only firm reference point for what this lens is worth at saleroom level today. With just one verified sale, there is no meaningful range or median to quote, but the price reflects Cosina's position as a budget-tier maker rather than a collectible name, and clean copies typically sell for similar low double-digit figures in the auction market before commission.