Canon Macro Twin Light MT-26EX-RT Instruction Manual page 77

If high-speed sync is set, the setting range will be 1/1 - 1/64.
When <j> is set, set A, B, or C as the firing group for the slave
units. The flash will not fire if it is set to D or E.
To fire multiple slave units with the same flash output, select <j>
in step 2.
q: Multiple Flash Photography with Manual Flash Output
Set the flash output.
4
Press function button 3 <1> or
<8>.
Turn <9> to set the flash output,
then press <8>.
Repeat steps 3 and 4 to set the flash
output of all groups.
Take the picture.
5
Each group fires at the set flash
output.
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