The Canon Speedlites Macro Twin Lite MT-24EX Flash 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. Direct attachment for EF 50mm f/2.5 Compact Macro EF 100mm f/2.8 Macro (non-IS version) and MP-E 65mm Macrophoto lenses require no adapters. The EF 180mm f/3.5L Macro USM is usable via Macrolite Adapter 72C and EF 100mm f/2.8L Macro IS USM via use of Macrolite Adapter 67. Or can be used with other lenses with the use of a matching Macrolite adapter.