Canon MT-26EX-RT Macro Twin Lite - Manual (Page 84)

84
: Optical Transmission Wireless Multiple Flash Photography
Slave A is controlled to fire with flash head A and slave B to fire with
flash head B as a group (as a single flash unit). Multiple units can also
be set as slave C. Note that there is no limit for the number of units that
can be used as slave A, B, or C.
Group Control
Slave C
Firing group C
Slave B Slave A
Firing group B
Flash head A
Firing group A
Flash head B