The Extender EF 2X III from Canon is designed for select Canon EF mount L-series telephoto lenses. It increases the focal length of a lens by a factor of 2x while still delivering superb image quality. It combines redesigned optics, improved data communication between lens and camera, and enhanced environmental protection to ensure the best possible image quality in all shooting conditions. The Extender EF 2x III features nine optical elements in five groups, ensuring improved visual performance. All optical elements have Canon's Super Spectra coating to reduce ghosting and flare. A new Fluorine Coating on the front and rear elements make marks, such as spots left by water or fingerprints, much easier to clean than standard coatings. A carefully positioned lens release mechanism also makes it easy to mount the extenders quickly, reducing the time that the camera and lens are exposed to the environment. The extenders offer the exceptional build quality expected from Canon's professional products, and are resistant to dust and water, allowing photographers to use them in extreme shooting conditions. A carefully positioned lens release mechanism makes it easy to mount the extender quickly, reducing the time the camera and lens are exposed to the environment.