This is the longest zoom lens among Canon's lineup, and a terrific selection for any long-distance application-outdoor sports, wildlife, news journalism, and so on. It's really lighter than Canon's EF 600mm f/4L IS lens, consideration just below ten lbs. It uses a refined optical style, with 2 fluorspar lens parts, one UD part, and one Super-UD-glass part, for outstanding correction of color fringing and very good distinction and sharpness. This super-telephoto lens uses magnesium-alloy barrel construction to reinforce its light-weight weight, and has weather-resistant gaskets throughout to be used in harsh conditions. It's compatible with each the EF one.4x II and 2x II tele extenders for even additional reach: Eos cameras with forty five AF purposes can still give optical device at the middle AF point once the lens is employed with the one.4x extender. Finally, it's image stabilised, providing up to four stops of correction for camera shake. This makes it even additional sensible in several things.