The EF 100-400mm f/4.5-5.6L IS USM is Canon`s fourth Image Stabilizer lens. It is a high-performance L-series telephoto zoom lens offering sophisticated features and high image quality which is to succeed the existing EF 100-300mm f/5.6L lens. Besides having an Image Stabilizer, this new lens also features enhancements such as ring USM for silent AF, rear focusing, a longer focal length range, and fluorite and Super UD elements which correct secondary chromatic aberrations for high image quality. It is the first EF zoom lens to have both rear focusing and a floating system to obtain high image quality at all focal lengths. Compatible with Extender EF 1.4x and EF 2x. With the EOS 3, autofocusing (at the centre focusing point only) is possible while the EF 1.4x is attached to the lens.