Nikon Z8 User Manual page 712

5
Press any of the controls to which [Recall focus position]
was assigned in Step 1.
The saved focus position will be restored.
Although [Recall focus position] can be assigned to
multiple controls, the same focus position will be restored
regardless of the control used.
Holding a control to which [Recall focus position] is
assigned activates manual focus (MF), and the camera will
not refocus if the shutter-release button is pressed halfway
while the control is pressed.
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f2: Custom Controls (Shooting)