Canon PowerShot SX400 IS Black Manual (en)

[Servo AF] (
Tracking may not be possible when subjects are too small or 
move too rapidly, or when subject color or brightness matches 
that of the background too closely.
[AF-Point Zoom] on the [
] and [
] are not available.
The camera can detect subjects even if you press the shutter 
button halfway without pressing the [ ] button. After your shot, 
] is displayed in the center of the screen.
Shooting with Servo AF
 Still Images 
This mode helps avoid missing shots of subjects in motion, 
because the camera continues to focus on the subject and adjust 
the exposure as long as you press the shutter button halfway.
Configure the setting.
Press the [
] button, choose 
[Servo AF] on the [
] tab, and 
then choose [On] (
The focus and exposure are 
maintained where the blue AF 
frame is displayed while you 
are pressing the shutter button