Canon Extender EF 2x

The Canon Extender EF 2x III doubles the focal length of select Canon EF L-series telephoto lenses while holding onto excellent image quality. Redesigned optics, nine elements in five groups with Canon's Super Spectra coating, cut down on ghosting and flare, and a fluorine coating on the front and rear elements sheds fingerprints and water spots far more easily than a standard coating.

An integrated processor keeps focusing, metering, and lens ID data flowing between the extender and camera body, so autofocus stays accurate even on moving subjects when paired with compatible L-series glass. Note that attaching the 2x extender costs two stops of maximum aperture. The housing is sealed against dust and moisture and built for tough field conditions, with a release mechanism designed for quick mounting so the camera and lens spend less time exposed to the elements. It works with fixed focal length L-series lenses 135mm and up, plus the EF 70-200mm f/2.8L, EF 70-200mm f/2.8L IS, EF 70-200mm f/4L, and EF 100-400mm f/4.5-5.6L.