Review: Pentax 40mm pancake lens By
Andrew Alexander (Wednesday, March 19, 2008 - 13:28 EDT)The 40mm ƒ/2.8 SMC P-DA limited edition is a fixed-focal length ''pancake'' lens, one of the smallest lenses to bear that moniker, and probably the smallest that Pentax produces.
A pancake lens is typically constructed with the fewest number of lens elements possible, and in this case the 40mm is no exception, with just 5 lens elements in four groups. The lens weighs just 90gm (3.2 oz), and is described by Pentax as being designed for use with digital cameras. We mounted the 40mm ƒ/2.8 on a Pentax film body, and could find no evidence of vignetting. However, our film body doesn't have aperture control, which would make it hard to use effectively as the 40mm ƒ/2.8 isn't equipped with an aperture ring. The lens takes both 30.5mm and 49mm filters in an interesting lens cap/hood design, and is available now for around $250.
Review: Pentax 40mm pancake lens