Nikon Z9 Mirrorless Camera - Manual (Page 128)

128 Focus
A Locking Focus with the AF-ON Button
• The AF-ON button can be used for focus in place of the shutter-release
button.
• When [ AF-ON only ] is selected for Custom Setting a6 [ AF activation ],
focus can be initiated only by pressing the AF-ON button; the camera will
not focus when the shutter-release button is pressed halfway. Focus will
remain locked after the
AF-ON button is released. To end focus lock, press
the AF-ON button again.