Canon EOS 70D Operation Manual - Page 203

Using Wireless FlashN The camera's built-in flash can work as a master unit with Canon Speedlites with a wireless slave feature via optical transmission and wirelessly trigger the Speedlite(s) to fire. Be sure to read about wireless flash photography (optical transmission) in the Speedlite's instruction manual. Slave Unit Settings and Position Regarding your Speedlite (slave unit), refer to its instruction manual and set it as follows. The settings other than the ones below for the slave unit's control are all set with the camera. Different types of Canon Speedlite slave units can be used and controlled together. (1) Set the external Speedlite as a slave unit. (2) Set the external Speedlite's transmission channel to the same channel as set on the camera.*1 (3) If you want to set the flash ratio (p.210), set the slave unit ID. (4) Position the camera and slave unit(s) within the range shown below. (5) Face the slave unit's wireless sensor toward the camera.*2 Example of Wireless Flash Set-up Indoors Outdoors Approx. 7 m Approx. (23.0 ft.) 80° Approx. 10 m (32.8 ft.) Approx. 5 m Approx. 7 m (16.4 ft.) (23.0 ft.) 203