Canon PowerShot SX400 IS Black Manual (en)

The digital tele-converter cannot be used with digital zoom 
= 64) or AF-point zoom (= 78).
The shutter speed may be equivalent when you move the zoom 
lever all the way toward [
] for maximum telephoto, and when 
you zoom in to enlarge the subject to the same size following step 
2 in “Zooming In Closer on Subjects (Digital Zoom)” (
Changing the AF Frame Mode
 Still Images 
Change the AF (auto focus) frame mode to suit the shooting 
conditions as follows.
Press the [
] button, 
choose [AF Frame] on the [
tab, and then choose the desired 
option (
 Still Images 
One AF frame is displayed in the center. Effective for reliable focusing.
A yellow AF frame is displayed with [
] if the camera cannot 
focus when you press the shutter button halfway.