Using Wireless Flash - Canon EOS 7D Mark II (G) Instruction Manual

Using Wireless FlashN
The camera's built-in flash can work as a master unit for Canon EX-
series, external Speedlites having a wireless slave feature. It can
wirelessly trigger the Speedlite(s) to fire via optical transmission.
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 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.*
(3) For flash ratio control, set the slave unit's firing group.
(4) Position the camera and slave unit(s) within the range shown
below.
(5) Face the slave unit's wireless sensor toward the camera.*
Indoors
Outdoors
272
Example of Wireless Flash Set-up
Approx. 80°
Approx. 5 m
(16.4 ft.)
1
Approx. 7 m
(23.0 ft.)
Approx. 7 m
(23.0 ft.)
2
Approx. 10 m
(32.8 ft.)