Canon SPEEDLITE EL-1 Advanced User's Manual page 132

About Sender Unit(s)
You can designate two or more sender units. When using multiple cameras with senders
attached, you can switch cameras in wireless strobe shooting using the same lighting
(receivers).
When two or more sender units are used, <
Caution
When the <
means that the unit is not connected yet. After checking the transmission channel
and wireless radio ID, turn each receiver unit off and on again.
Limit the total number of senders and receivers during radio transmission wireless
shooting to 16 units.
Note
You can shoot even when the sender unit is in the sub-sender state.
> lamp turns off or <
> is displayed on the LCD panel.
> is displayed on the LCD panel, it
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