Custom button map
How do you assign the custom controls on a Nikon Z6 III — and which functions can each button actually hold?
Work at the f2 desk
All stills assignments are made at Custom Setting f2: highlight a control, press the center button, choose a role. The bench includes Fn1, Fn2, AF-ON, the sub-selector center, the video record button, the command dials, and controls on the lens. Video assignments live separately at g2 Custom controls — a map built for stills does not follow you into video mode.
Fn1 — the tracking grab
Assign Fn1 the role AF-area mode + AF-ON and preset its area to 3D-tracking. Holding Fn1 switches the camera to that area and starts autofocus; releasing it restores the AF-area mode you were using. It is a borrow, not a switch — built for the seconds when your everyday area loses the subject.
Fn2 — switch eyes; video button — DX reach
Fn2 takes Switch eyes: with a human or animal subject detected, a press moves focus between the subject's eyes. The video record button — idle in photo mode — takes Choose image area: press and turn a command dial to move between FX and the DX crop for instant reach. Both roles come straight from Nikon's f2 table.
Save the map to U1
Register the finished map to U1 so a reset or a firmware day cannot take it. If your video work matters, spend two minutes at g2 Custom controls mirroring the roles you rely on — the maps are independent.
Assign the three roles, then hold Fn1 on a walking subject and release it. The override you feel is the map working.