Canon Extender EF 2X IIIDesigned to extend a lenses focal length by a factor of 2x, the redesigned Canon Extender EF 2X III delivers optical performance on par with the finest Canon super telephoto lenses. It features a built in microcomputer for seamless communication among camera body, lens and extender, features careful lens placement and coatings to minimize ghosting, flare and chromatic aberration, and even has a new Fluorine coating that keeps soiling, smears,