Canon EOS 7D Mark II Instruction Manual page 282

Using Wireless FlashN
Creative Wireless Flash Shooting
Flash exposure compensation
When [Flash mode] is set to [E-TTL II], flash exposure
compensation can be set. The flash exposure compensation
settings that can be set (see below) vary depending on the
[Wireless func.] and [Firing group] settings.
FE lock
If [Flash mode] is set to [E-TTL II], you can press the <B>
button to perform FE lock (p.258).
282
Flash exposure compensation
The flash exposure compensation is
applied to the built-in flash and all the
external Speedlites.
2 exp. comp.
The flash exposure compensation is
applied to the built-in flash.
1 exp. comp.
The flash exposure compensation is
applied to all the external Speedlites.
A, B exp. comp.
The flash exposure compensation is
applied to both groups A and B.
Grp.C exp. comp.
The flash exposure compensation is
applied to group C.