The Extender EF 1.4X 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 1.4x while still delivering superb image quality. To ensure the best possible image quality in all shooting conditions, it combines redesigned optics, improved data communication between lens and camera, and enhanced environmental protection. To facilitate the accurate transfer of imaging data between the lens and camera body, the extender features an integrated processor which ensures all focusing, metering, and ID information is available - allowing the photographer to capture balanced, well-exposed images.
Canon 4409B002 Specs