This remarkable lens is the longest in the world with full autofocus capability. Two fluorite elements for superb image quality, make it ideal for many professional applications where it's impossible to get close to the subject. Fully compatible with any EOS SLR, including digital bodies, autofocus performance is silent and instantaneous thanks to the Ultrasonic Motor. It's also compatible with the Canon Extender EF 1.4x II (making it a 1700mm f/8) and EF 2x II (2400mm f/11). Available upon special order.