Canon Speedlite EL-5 Advanced User's Manual page 114

LCD Panel Illumination
In wireless flash photography, the sender LCD panel is on or off depending on whether
senders and receivers (firing groups) are charged.
The sender LCD panel is lit when the sender and receiver are not fully charged. LCD panel
illumination turns off approx. 12 sec. after senders and receivers are fully charged.
The sender LCD panel is lit again when sender and receiver charging resumes as you take
pictures.
Caution
< > is displayed on the sender LCD panel as long as the sender or any
receiver (firing groups) is not fully charged. Before shooting, confirm that
< > is not displayed on the LCD panel.
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