When your telephoto lens isn't quite long enough, the Extender EF 2X III Teleconverter from Yongnuo can help you double its reach. Designed to work with select Canon EF mount lenses, this teleconverter provides a 2x magnification factor that effectively doubles the focal length of your lenses. This takes a 400mm f/2.8 and transforms it into an 800mm f/5.6. Featuring electronic communication from the lens to the camera, this teleconverter allows for all standard functions of the lens to work as normal, including autofocus and image stabilization.
