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

a: Wireless Multiple Flash Shooting with Flash Ratio
Set flash exposure compensation 
as required.
Press function button 3 <F>, 
turn <9> and select <6>.
Press function button 3 <B>.
Turn <9> to set the flash exposure 
compensation amount, and press the 
<8> button.
Press function button 4 <?> to 
return to the shooting-ready state.
If you need more flash output or wish to 
perform more sophisticated lighting, you 
can increase the number of slave units. 
Simply set an additional slave unit to the 
firing group (A, B or C) whose flash 
output you want to increase. There is no 
restriction on the number of units.
For example, if you set a firing group with three slave units to <4>, 
the three units are treated and controlled as a single firing group A with 
a large flash output.
Slave Group Control
Gr = A
Gr = A
Gr = A
Firing group A
To fire the three firing groups A, B and C at the same time, set 
<^>. With the <%> setting, firing group C does 
not fire.
If you shoot with firing group C pointing directly toward the main subject, 
overexposure may result.
In some EOS film cameras that support E-TTL autoflash, you cannot 
perform multiple flash wireless shooting with a flash ratio setting.
The flash ratio of 8:1 to 1:1 to 1:8 is equivalent to 3:1 to 1:1 to 1:3 (1/2-
stop increment) when converted to number of stops.
The details of the flash ratio settings are as follows.