Canon SPEEDLITE EL-1 Advanced User's Manual page 190

6.
Select a firing group.
If you selected <
vertically and then push the joystick up and down, or turn <
select the group to set the flash output.
7.
Set the flash output.
Push the joystick vertically.
Push the joystick to the left or right or turn <
then push the joystick vertically.
Repeat Step 3 and 4 to set the flash output of all the groups.
8.
Take the picture.
Each group fires at the set flash output.
Note
When set to <
B, or C. All the groups fire at the set flash output.
> or <
>, the firing group setting of the receiver unit can be either A,
190
> in Step 2, push the joystick
> to set the flash output,
> to