Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 198)

Flash Function Settings
Flash Firing
E-TTL Balance
E-TTL II Flash Metering
Continuous Flash Control
Flash Sync Speed in Av Mode
Flash Function Settings
Flash Custom Function Settings
Clearing Flash Function Settings/Clearing All Speedlite Custom Functions
Functions of EL/EX Series Speedlites compatible with flash function settings can be set via
a camera menu screen. Attach the Speedlite to the camera and turn on the Speedlite before
setting the flash functions.
For details on the Speedlite's functions, refer to the Speedlite's Instruction Manual.
1.
Select [ : External Speedlite control].
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