The Speedlite 600EX-RT is Canon's new flagship flash designed for professional photographers, especially those who frequently use multi-flash photography in the studio. With its ability to use radio transmissions to communicate with other Speedlites, the Speedlite 600EX-RT supports both radio and optical communication for maximum versatility. The AF-assist beam of the Speedlite 600EX-RT supports the new 61-point AF system of the new EOS-1D X and EOS 5D MARK III cameras, and is effective up to 10 meters away. It also makes use of a new dot-matrix LCD that provides detailed information on settings and features with a more intuitive user-interface and thus easier to view.