Nikon D7200 body - Manual (Page 192)

168
Image Area
Selecting 1.3Ч (18Ч12) for Image area in the movie shooting
menu (
0 274) reduces the angle of view and increases the
apparent focal length of the lens. Note that movies recorded at
the same frame size but with different image areas may not have
the same resolution.
DX (24Ч16) 1.3Ч (18Ч12)