Canon Extender EF 1.4x III and Canon Extender EF 2x III
Canon has also done some serious upgrading in the extender department. Both have fluorite coating on the front and back elements, plus an anamolous dispersion lens element to help prevent image degradation. They have also upgraded the internal microcomputer to help improve AF performance when used with an IS Series II EF super-telephoto lens. Both will hit shelves in December for $500 each.