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

Troubleshooting Guide
Optical Transmission Wireless Shooting
Set the master unit to <:> <M> and set the slave unit to 
<:> <x> (p.78).
Set the transmission channels of the master unit and slave unit to the 
same numbers (p.78).
Check that the slave unit is within the transmission range of the master 
unit (p.76).
Point the wireless sensor on the slave unit toward the master unit 
If the master unit and slave unit are too close, the transmission may not 
operate properly.
When using the camera’s built-in flash as the master unit, raise the 
camera’s built-in flash, and set the wireless function in [Built-in flash 
func. setting
] on the camera’s menu screen.
Even when master flash firing is set to OFF <d>, the master flash fires 
a small flash to control the slave unit with optical transmission (p.79).
When using autoflash shooting with three firing groups A, B and C, do 
not fire with firing group C pointed toward the main subject (p.87).
The slave unit does not fire.
The master unit’s flash fires.
Pictures are overexposed.