The Pentax HD DA Fisheye 10-17mm f/3.5-4.5 ED Lens is a high-performance, ultra wide-angle zoom lens for K-mount APS-C cameras. Its 35mm focal length equivalency is 15.0-25.5mm with a 180° view at the 10mm setting that takes in more than the human eye sees, with a dramatic curvature of field. At the 17mm end of the zoom, it is a very wide-angle lens. This lens also features an HD lens coating and an optical design with an ED element that effectively compensates for chromatic aberration for extra-clear, high-contrast images.