Canon Speedlite 580EX II Flash for Canon EOS Digital SLR Cameras E-TTL II evaluative flash metering for critically accurate exposure High output with maximum guide number 190 at 105mm setting (ISO 100, feet) Autozoom head covering a range of 24-105mm or as wide as 14mm with built-in widepanel engaged High-speed (FP) sync mode, Flash Exposure Bracketing (FEB) and Flash Exposure (FE) Lock Built-in transmitter and receiver offering fully wireless automatic flash with up to three groups of multiple Speedlites that can be controlled from the 580EX or optional Wireless Transmitter ST-E2