The Dallmeyer 5 Inch f/2.9 Pentac is a large-format British lens with a roughly 127mm focal length and an f/2.9 maximum aperture. The Pentac was a fast portrait and aerial-reconnaissance type lens, and copies turn up today on view-camera and projection mounts as well as in adapted form for medium and large format use.

At recent UK auction, hammer prices for the 5 Inch f/2.9 Pentac have sat in a tight £81–£126 band, with a median around £125 based on three saleroom results between 2023 and 2026. As of 2026, that range reflects what clean working examples sell for at wholesale auction level rather than retail dealer asking prices, so a tidy copy is typically worth around the upper end while scruffier or partial examples drop toward the lower figure.