Canon 580EX Speedlite Mark II TTL 

The new Canon 580EX is, certainly, E-TTL (and E-TTL II) compatible, and it has a guide number of 58 meters at ISO 100 and 105mm focal length. It's both smaller and lighter than the 550EX which it substitutes. One most important new feature for digital shooters is that the flash now knows the sensor size of the EOS 20D and zooms the flash head to give full exposure over only the area seen by the sensor.

The Canon Speedlite 580EX II Flash features a more-rugged build excellence with a metal foot being one of the mainly noticeable changes. But the good news is that the metal foot is attached to a plastic mount inside the flash. Bad in that it will still be the part that breaks, but good that your camera likely will not be the part that breaks. Visible dust and water resistance indicators symbolize another update this flash has received. This is Canon's first weather-resistant flash. Dust and water resistance is a quality that is going to be in intense demand from sports and photojournalism photographers.

Canon 580EX Speedlite Mark II TTL Flash

Speedlite 550EX flash, Canon has further improved the new model by plummeting the full-power recycling time by about 25 percent, while increasing the utmost Guide Number power rating by about 50 percent. These developments are possible because of flash head optimization, circuit resistance reductions and alteration in circuit design.

The Canon Speedlite 580EX Flash also features an AF-assist beam, which is now better matched to the different focusing point arrangements of various EOS SLRs, compared to previous models. The unit comprises a swivelling flash head that turns a full 180 degrees in both directions, while a single release lock controls tilt and swivel adjustments. A wide-angle diffuser found on the Speedlite 580EX flash covers focal lengths as short as 14mm.

The Canon Speedlite 580EX II Flash can control and be controlled by compatible Canon Speedlites as well as the Canon ST-E2 Wireless Transmitter for a very transportable and flexible lighting system. The Canon 580EX II is capable to control ratios in up to 3 groups (A/B/C - C is for background light only).