Canon PowerShot SX400 IS Black Manual (en)

Using Eco Mode
This function allows you to conserve battery power in Shooting 
mode. When the camera is not in use, the screen quickly darkens 
to reduce battery consumption. 
Configure the setting.
Choose [Eco Mode], and then 
choose [On].
] is now shown on the 
The screen darkens when 
the camera is not used for 
approximately two seconds; 
approximately ten seconds after 
darkening, the screen turns off. The 
camera turns off after approximately 
three minutes of inactivity.
To activate the screen and 
prepare for shooting when the 
screen is off but the lens is still 
out, press the shutter button