Complete with built-in radio transmission wireless functionality, the Speedlite 600EX II-RT sits at the top of Canon's on-camera E-TTL / E-TTL II compatible flash lineup with a powerful guide number of 197' at ISO 100 and 200mm. This revision improves continuous flash performance by 1.1-1.5x, or up to 2.0x with optional battery pack, simplifies the menu system for faster operation, and includes a specially designed bounce adapter, a hard color filter, and an updated soft case. The two-way 2.4 GHz radio system provides added reliability and a range up to 98.4' among up to 5 groups with a total of 15 individual Speedlites. This system also does not need direct line-of-site like traditional optical-based transmission and will work through obstacles.

For added coverage and functionality, the flash's zoom head can reach from 20-200mm, with the option for wide 14mm coverage when the built-in diffusion panel is used. Also, the unit can tilt from -7 to +90° and rotate 180° either left or right for complete bounce capabilities. On the back of the 600EX II-RT is a backlit dot-matrix LCD panel that displays the status and allows users to easily access and change settings. Additionally, the flash is durable with a redesigned contact construction and improved dust and water resistant sealing.

Other capabilities of the 600EX II-RT include a stroboscopic mode as well as high-speed, first and second curtain sync settings for more control over your image's final look. The flash is powered by 4 AA batteries and has a port for an optional external power pack. The rated recycle time is 0.1-5.5 seconds, but can be sped up to 0.1-3.3 seconds in Quick Flash mode. It comes with a bounce adapter, a hard CTO filter set, a mini stand, and an updated soft case that holds the flash and accessories.

AF assist beam works with up to 61-point High Density Reticular AF system There are 15 custom functions and 6 personal functions for maximum customization Optical transmission is available in addition to radio transmission Quick Flash settings speeds up recycle time and flash duration Manual power settings from 1/1 to 1/128 power in 1/3-stop increments Flash color temperature information is automatically transmitted to the camera Automatic power off function Flash exposure compensation from -3 to +3 EV in 1/2 or 1/3 EV steps PC sync port and remote release terminal for off-camera triggering Flash duration of 1.8 ms or less, or 2.3 ms or less in Quick Flash mode Stroboscopic setting from 1-500 Hz, or 1-199 Hz during optical transmission wireless shooting Wireless flash ratio control from 1:8 to 1:1 to 8:1 in ½-stop increments Compatible with ST-E3 Speedlite Transmitter Approximately 100-700 flashes with AA alkaline batteries Locking metal foot Bracket mounting hole Built-in retractable bounce card