As the Canon top-of-the-line flash for the EOS-system, the Speedlite 580EX II takes the best features from existing models and adds functionality that enhances digital photography. A more powerful flash with a maximum guide number of 191'(58 m) at ISO 100 (at 105mm focal length), faster recycling, more consistent color and enhanced controls are among the improvements that all photographers, especially those who shoot digital, will find useful. The 580EX version II offers several improvements over the original 580EX version. It has been redesigned to match with the EOS-1D Mark III in terms of improved dust- and water-resistance, body strength, and the ability to control flash functions and settings from the camera menu (EOS-1D Mark III only). Other features include improved communication reliability through its direct contacts, a metal hot shoe, and recycling time is both 20% shorter than the 580EX and is completely inaudible. The flash supports all current versions of TTL, including evaluative E-TTL II. This is great for photographers that shoot high contrast or reflective subjects, like those encountered in wedding photography. Photographers can now capture every detail from the black of tuxedos to the white of wide smiles and wedding dresses. Compatibility The Speedlite 580EX flash is compatible with Canon's E-TTL II (Evaluative Through The Lens) auto exposure technology. When combined with a compatible Canon camera (EOS-1D/s Mark II, Mark III, D-20, Elan 7N/E, or newer models) and compatible lens, E-TTL II utilizes subject distance and other information that automatically modifies flash power, resulting in accurate flash exposure regardless of subject size, reflectance, or photographic composition. Multiple Flash Exposure Modes E-TTL II, E-TTL, TTL & Manual Faster Recycling Time Improved power supply design provides up to 25% improvement in flash recycle time  Built-in AF-assist beam compatible with EOS multi-point AF systems including 45-point Area AF types  Built-in catchlight reflector allows a catchlight to be added quickly and conveniently to portraits Professional Modes • FE Lock - Flash exposure lock • FP Mode, or high-speed sync, allows the camera to sync with flash at higher shutter speeds • Second-curtain sync fires the flash at the end of the exposure, allowing streak of light to flow naturally behind the movement of the subject • Wireless TTL flash when combined with ST-E2 Transmitter & multiple 550 EX's • Stroboscopic mode shows several minute flashes continuously to easily view flash effect • FEB - Flash Exposure Bracketing • 14 Custom Functions that provide maximum control over various flash functions • Ratio flash lighting of up to 8:1 when used with ST-E2 Transmitter & multiple 550 or 580EX's • When color temperature data is automatically transmitted from the 580EX, the camera sets the color balance for the optimal flash shot