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. It is ideal for photojournalists and wildlife, nature and sports photographers who need to get close to distant and challenging subjects and it reduces the need to carry heavy telephoto lenses.
Note from Canon: This convertor is only compatible with fixed focal length L-series lenses
135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/2.8L IS II, EF 70-200/2.8L IS III, EF
70-200/4L IS, EF
70-200/4L IS II, EF 100-400/4.5-5.6L, and EF 100-400/4.5-5.6L IS II. Additionally, please see the lens
and/or camera body manual for full compatibility information with the
Extender EF 1.4X III. AF speed and IS function may be limited or not functional when used with a extender.