Canon EOS REBEL T6i Instruction Manual page 187

[1 (A:B)] Firing multiple slave units in multiple groups
A
If [Firing group] is set to [1 (A:B)], group C will not fire.
The 8:1 to 1:1 to 1:8 flash ratio is equivalent to 3:1 to 1:1 to 1:3 stops (1/2-
stop increments).
You can divide the slave units into
groups A and B, and change the flash
ratio to obtain the desired lighting effect.
Refer to the Speedlite's instruction
manual and set one slave unit to firing
group A and the other to firing group B.
Position the Speedlites as shown in the
B
illustration.
Select [Wireless func.].
1
Follow step 2 on page 185 to select

[0], then press <0>.
Set [Firing group] to [1 (A:B)].
2
Set the A:B flash ratio and shoot.
3
Select [A:B fire ratio] and set the

flash ratio.
Custom Wireless Flash ShootingK
187