Sony a9 II Help Manual page 58

[Eye AF] by custom key
The Eye AF function can also be used by assigning [Eye AF] to a custom
key. The camera can focus on human eyes as long as you are pressing the
key. This is useful when you want to temporarily apply the Eye AF function
to the entire screen regardless of the setting for [Focus Area]. The camera
does not focus automatically if no faces or eyes are detected.
(Note: When you try to focus on eyes by pressing the shutter button
halfway down, the camera only detects faces or eyes inside the focus area
designated with [Focus Area]. If the camera detects no faces or eyes, it
performs normal auto-focusing.)
 MENU 
Custom Key]  desired key, then assign the [Eye AF]
[
function to the key.
 MENU 
[Subject Detection]  desired setting.
 Point the camera at the face of a human or animal, and
press the key to which you have assigned the [Eye AF]
function.
To shoot a still image, press the shutter button while pressing the key.
[Switch Right/Left Eye] by custom key
When [Subject Detection] is set to [Human] and [Right/Left Eye Select]
is set to [Right Eye] or [Left Eye], you can switch the eye to be
detected by pressing the custom key to which you have assigned the
[Switch Right/Left Eye] function.
When [Right/Left Eye Select] is set to [Auto], you can temporarily switch
the eye to be detected by pressing the custom key to which you have
assigned the [Switch Right/Left Eye] function.
The temporary left/right selection is cancelled when you perform the
following operations, etc. The camera returns to automatic eye detection.
• Pressing the center of the control wheel
• Pressing the center of the multi-selector
• Stopping pressing the shutter button halfway down (only during still
image shooting)
• Stopping pressing the custom key to which [AF On] or [Eye AF] is
assigned (only during still image shooting)
• Pressing the MENU button
GB
58
(Camera Settings 2)  [
(Camera Settings 1)  [Face/Eye AF Set.] 
Custom Key] or