The 600EX-RT offers radio controlled, two-way wireless transmission up to 98.4 feet, among up to 5 groups with a total of 15 individual speedlites. Communicating on 2.4 GHz frequencies, it doesn't have the same directional limitations of traditional wireless optical transmitters. Where other wireless signals can be interrupted by physical obstacles, radio controlled systems excel. 15 transmission channels are available, selectable manually or automatically, and radio transmission IDs can be set to prevent misfiring in the event of signal interference on the same channel

The included color filter holder and two orange color filters multiply your creative options--the holder is compatible with Canon as well as third-party gelatin filters. The 600EX offers several other improvements--it's been redesigned, with a metal hot shoe, improved dust- and water-resistance and body strength, plus the ability to control flash functions and settings from the camera menu.  A dot matrix LCD panel and backlit button deliver much-improved visibility.

The flash supports all current versions of TTL, including evaluative E-TTL II. This is great for photographers who 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 wedding dresses. The 600EX-RT is compatible with all E-TTL II/E-TTL autoflash EOS DSLRs.

New wireless multiple flash system using radio wave communication for enhanced control of up to five groups of flashes

Zoom flash head covers wide range of 20-200mm; maximum Guide Number--197' (60 m) at ISO 100

Redesigned contact construction, improved flash head durability, and exceptional dust and weather resistance for reliable operation

Built-in AF-assist beam compatible with Canon's new 61-Point High Density Reticular AF

Dot matrix LCD panel and backlit button provide easy visibility.

Color filter holder for attaching Canon and third-party color gelatin filters

18 Custom Functions for creative flexibility

Full swivel, 180° in either direction