Rollei Profi Funk-Sender Instructions page 54

Canon master control M mode
54
2) After the mode has been selected and nothing else has been changed so far,
press the left and right button to set the power output for group A . Press the
up and down button to set the flash ratio between Off, A:B and A:B:C .
If the flash ratio off is chosen that means that all flash groups have the same
power output . If the ratio A:B is selected the groups A and B are enabled and
the power of both groups can be set individually . If the ratio A:B:C is selected
all groups are enabled and the power of each group can be set individually .
3) Group B flash power output (A:B or A:B:C)
Press the OK button repeatedly until the arrow is indicating the group B . Press
the left and right button to set the output power of group B .
ENGLISH
A:B A:B C