Canon Speedlite 600 EX-RT User Manual (en, zh)

Flash Control from Camera’s Menu Screen
Zoom (flash coverage)
You can set the flash coverage for the Speedlite. When [Auto] is 
selected, the flash coverage is set automatically according to the 
focal length of the lens.
Wireless flash functions (setting)
You can perform wireless flash shooting. Two wireless flash shooting 
methods are available; radio transmission and optical transmission. 
For details, see Chapter 4 and Chapter 5.
Clear Speedlite (function) settings
You can return the flash settings to their default settings.
When flash exposure compensation is set on the flash, you cannot set flash 
exposure compensation in the camera’s menu screen. Note that if both are 
set at the same time, the setting on the flash is given priority.