Canon Speedlite 600EX II-RT Manual (en)

a: Fully Automatic Wireless Flash Photography
Position the camera and the flash.
Position them within the range shown 
on page 90.
Set the flash mode to <a>.
Press the <E> button on the 
master unit.
Turn <9> to select <Q>, then 
press <8>.
The slave unit is set automatically to 
<a> during shooting, controlled 
by the master unit.
Check that the firing group control is 
set to <t>.
Check that the flash is ready.
When the slave flash is ready, the AF-
assist beam emitter blinks with 
approx. 1-second intervals.
Check that the master unit’s flash-
ready lamp is lit.
If there is a fluorescent light or computer monitor near a slave unit, the 
presence of the light source may cause the slave unit to malfunction and 
fire inadvertently.
During optical transmission wireless shooting, even if the master and 
slave units (firing group) are not all fully charged, <G> will not be 
displayed on the master unit’s LCD panel as it is with radio transmission 
wireless shooting (with master flash firing OFF). Also, there is no function 
for illuminating or turning off the master unit’s LCD panel according to the 
charge status of the master unit and slave units.
When C.Fn-20-1 is set on the master unit (p.116), the beep will sound 
when the master unit is fully charged. (This beep does not indicate that 
charging of all flash units is completed as it does with radio transmission 
wireless shooting.)