Nikon Z9 Mirrorless Camera - Manual (Page 218)

218 Video Image Area Options
The image area for videos can be selected using [ Image area ] >
[ Choose image area ] in the video recording menu. The crop used for
filming video varies with the option selected. Regardless of the option
selected, the aspect ratio is 16:9.
• Select [ FX ] to shoot videos in what is referred to as “FX-based video
format”, [ DX ] to shoot in “DX-based video format”.
• Selecting [ DX ] for [ Choose image area ] or mounting a DX lens on the
camera with [ 3840×2160; 120p ], [ 3840×2160; 100p ], [ 1920×1080;
120p ], or [ 1920×1080; 100p ] chosen for [ Frame size/frame rate ]
increases the apparent focal length by approximately 2.3× when
compared to FX format.
Video Image Area Options