Canon Speedlite 470EX-AI Instruction Manual page 23

Turning on the Power
The flash settings will remain in effect even after the power is turned off.
To retain the settings when replacing the batteries, replace the batteries
after turning off the power switch.
You can fire a test flash while the power switch is set to the <a>
position. Also, when a button or dial is operated, the LCD panel
illuminates.
Auto power off can be disabled (C.Fn-01, p.85).
When set as a receiver unit, you can change the time until the receiver
unit's auto power off takes effect (C.Fn-10, p.86).
You can change the setting of the LCD panel illumination (C.Fn-22, p.87).
You can change the color of the LCD panel illumination (P.Fn-02/03,
p.88).
You can disable Quick flash (P.Fn-05, p.89).
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