This super wide-angle zoom boasts the shortest minimum focal length, largest aperture, and broadest zoom range in its class. In addition to three types of aspherical lens elements (ground, replica, glass mold), two UD lens elements are used to correct a variety of aberrations. To meet the strict demands of professionals and dedicated hobbyists, image quality on the wide-angel end has been greatly enhanced over conventional models for sharp, high-contrast image reproduction. Use of a circular aperture diaphragm brings out the beauty of blurred areas. Magnification-type chromatic aberrations, as well as the flare / ghosting common in digital cameras, are also thoroughly controlled. Moreover, uncompromising dust-proof and drip-proof*1 design specifications allow shooting in severe conditions.