Sony ILCA-77M2 - Manual (Page 74)

3. Press the shutter button fully down to shoot the image.
Note
[Center Lock-on AF] may not function very well in the following situations:
The subject is moving too quickly.
The subject is too small, or too large.
The contrast between the subject and the background is poor.
It is dark.
The ambient light changes.
Lock-on AF does not work in the following situations:
In [Sweep Panorama] mode
When [Scene Selection] is set to [Hand-held Twilight]
When using [Smart Telecon.]
When shooting in Manual Focus mode
When the subject to be tracked disappears from the screen, Lock-on AF is released.
When [Center Lock-on AF] is set to [On], the camera may not be able to resume tracking for a while
after it loses the track of the subject.
[69] How to Use Using shooting functions Adjusting the focus
AF Area Auto Clear
Sets whether the focus area should be displayed all the time or should disappear automatically shortly
after focus is achieved.
1. MENU
→
(Custom Settings
) → [AF Area Auto Clear] → desired setting.
Menu item details
On:
The focus area is displayed all the time.
Off (default setting):
The focus area disappears automatically shortly after focus is achieved.