Canon U.S.A. Announces the Availability of the Versatile EF 200‐400mm F/4L IS USM Extender 1.4x Super-Telephoto Zoom Lens Award-Winning Photographer Shares First-Hand Experiences with the EF 200-400mm ...

As a 1.4x teleconverter, the focal length of the attached lens is magnified by a factor of 1.4x, with a 1 f/stop reduction in aperture rating, so a 70-200mm f/2.8 zoom effectively becomes roughly a ...