Canon PowerShot SX70 HS Digital Camera - Manual (Page 110)

Changing the Focus Setting
Continuous AF constantly focuses on subjects the camera is aimed at, even
when the shutter button is not pressed. This setting can be changed to limit
autofocusing to the moment you press the shutter button halfway.
1
[Continuous AF]
Enable
Helps avoid missing sudden photo opportunities,
because the camera constantly focuses on subjects
until you press the shutter button halfway.
Disable
Conserves battery power, because the camera does
not focus constantly. However, this may delay focusing.
110