You can create two or three slave groups and set the flash ratio for E- TTL II autoflash shooting (p.41 - 45).
Wireless flash with two slave groups (p.41)
Indoors
15m
A(49.2ft.)
Outdoors
10m
(32.8ft.) B
80o
8m (26.2ft.) 12m (39.4ft.)
Wireless flash with three slave groups (p.43)
Indoors
C
15m
A(49.2ft.)
Outdoors
10m
(32.8ft.) B
80o
8m (26.2ft.) 12m (39.4ft.)
35