The Canon Speedlite 600EX II-RT comes complete with built-in radio transmission wireless functionality, and 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.

Features:

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