Canon EOS Rebel T3i EOS REBEL T3i / EOS 600D Instruction Manual - Page 190

Using Wireless FlashN 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 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 Speedlite as a slave unit. (2) Set the Speedlite's transmission channel to the same one as the camera's.*1 (3) If you want to set the flash ratio (p.196), 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 Wireless flash set-up example Indoors Outdoors Approx. 7m Approx. (23.0ft.) 80o Approx. 10m (32.8ft.) Approx. 5m Approx. 7m (16.4ft.) (23.0ft.) *1: If the Speedlite does not have a transmission channel setting function, the camera can work with any channel. *2: In small rooms, the slave unit may work even if its wireless sensor does not face the camera. The camera's wireless signals can bounce off the walls and be received by the slave unit. With EX-series Speedlite having a fixed flash head and wireless sensor, make sure it fires, then take the picture. 190