This Ring Lite for close-up and macro shooting is loaded with advanced features, including all E-TTL functions with the EOS-1V, EOS-3 and other E-TTL cameras, including FE Lock and FP (high-speed) Sync. Circular twin flash tubes can fire at even power or varied between them over a 6-stop range, and one or more 550EX Speedlites can be used as wireless slaves along with the MR-14EX. Designed to attach directly to the 50mm f/2.5, 100mm f/2.8 (both versions) and MP-E 65mm Macro Lenses. A built-in flash exposure bracketing works in TTL mode with any EOS camera body. Also features incandescent focusing lamps and two forms of modeling flash permit preview of lighting effects. The MR-14EX is compatible with lithium-type AA batteries, and accepts optional external battery packs.Sophisticated control includes Wireless E-TTL and Ratio Control w/ EOS-1v, ELAN 7 Series, Rebel T2, Ti, K2, EOS-1Ds / D Series, 5D Mark II, 5D, 50D, 40D, 30D, 20D, 10D, D60, D30, Rebel T1i, Rebel XSi, Rebel XS, Digital Rebel XTi, Digital Rebel XT, Digital Rebel.