Nikon D500 - Manual (Page 94)

94 Menu Guide
This option determines the slowest shutter speed available
when using front- or rear-curtain sync or red-eye reduction in
programmed auto or aperture-priority auto exposure modes
(regardless of the setting chosen, shutter speeds can be as slow
as 30 s in shutter-priority auto and manual exposure modes or at
flash settings of slow sync, slow rear-curtain sync, or red-eye
reduction with slow sync).
Choose how the camera adjusts flash level when exposure
compensation is used.
e2: Flash Shutter Speed
G button
➜ A Custom Settings menu
e3: Exposure Comp. for Flash
G button
➜ A Custom Settings menu
Option Description
YE
Entire frame
Both flash level and exposure compensation are
adjusted to modify exposure over the entire
frame.
E
Background only
Exposure compensation applies to background
only.