The Canon MT-24EX TTL Macro Ring Light is a twin-flash set-up (similar to a ringflash) for the EOS system that has every feature and capability imaginable. Employing Canon's E-TTL, it takes full advantage of the flash performance of the EOS-1V, EOS-3, and other E-TTL supported cameras by allowing for shutter speeds above the normal sync range. Twin flashes fire at even power, or can be varied over an eight-stop range for dramatic directional lighting that emphasizes the relief of the subject. One or more 580EX, 550EX, 430 EX, or 420EX Speedlites can be used as wireless slaves along with the MT-24EX. The controller unit has an illuminated, informative LCD panel. Accepts optional hi-capacity battery packs.