The pentax 50mm f14 smc fa lens is a quality fast aperture prime lens on film cameras the 50mm focal length offers roughly the same field of view as the human eye and on digital cameras with aps c size sensors this lens becomes a useful portrait lens with a focal length equivalent of 75mm in 35mm film terms either way the maximum aperture of f14 offers superb low light performance and fantastic softness in the out of focus areas of the photograph another quality that lends itself well