Increases focal length of Canon L-series telephoto lens’ by 1.4x.

It's higher AF accuracy makes it ideal for press, sports and nature photography. It is also highly resistant to dust and water for use in harsh conditions. A built in micro computer enables effective communication between lens and camera. The lens coatings are optimised to minimise ghosting and flare plus its fluorine coating keeps the lens surface clean from water spots and fingerprints.