Canon Speedlite 600EX II-RT Manual (en)

Flash Control from the Camera’s Menu Screen
Zoom (flash coverage)
You can set the Speedlite flash coverage. When [Auto] is selected, 
the flash coverage is set automatically according to the focal length 
of the shooting lens and the image sensor size of the camera (p.26).
Wireless flash functions
You can set radio transmission wireless flash photography and 
optical transmission wireless flash photography. For details, see 
Chapter 4 (p.57) and Chapter 5 (p.89).
Clear settings
When [Clear flash settings] or [Clear external flash set.] is 
selected, you can revert the settings of Speedlite to their default 
[Flash firing] and [E-TTL II flash metering] are displayed in step 2 or 
step 3 on page 52. (Display layouts and procedures vary by camera 
When [Flash sync. speed in Av mode] is not displayed, it can be set 
with the camera’s Custom Functions.
When the flash exposure compensation is set on the flash, flash 
exposure compensation cannot be performed from the camera. If both 
are set at the same time, priority is given to the setting on the flash.
When the flash’s Custom Function C.Fn-05 is set to [1:TTL] (p.114), 
[TTL] can be selected when [Flash mode] is set. When performing 
autoflash photography with an EOS DIGITAL camera, set C.Fn-05 to 
If the flash coverage is automatically set such as when the bounce 
adapter is attached or the wide panel is used, setting [Zoom] (flash 
coverage) is not possible.