Nikon R1 Instruction Manual page 42

Procedures for Commander flash operation
Set the remote flash unit's flash mode on the
4
SU-800.
MODE
NO AF-ILL
READY
42
A B ON/OFF
SEL
LOCK
1
Press the [SEL](FUNC.) button to
display the flash mode (blinking) of
each group, then press [MODE]
button to set the flash mode to TTL.
Use of TTL mode is recommended for
normal flash shooting.