Extending a lenses focal length by a factor of 14x extender ef 14x iii incorporates phenomenal optical performance with minimal chromatic aberration and is a perfect complement to many of 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 and flare and even has a new fluorine coating that keeps soiling smears and fingerprints to a minimum an integral pa