Nikon D750 User Manual page 68

A
The Built-in Flash
If additional lighting is required for correct
exposure in i mode, the built-in flash will
pop up automatically when the shutter-
release button is pressed halfway. If the flash
is raised, photographs can only be taken
when the flash-ready indicator (M) is
displayed. If the flash-ready indicator is not
displayed, the flash is charging; remove your
finger briefly from the shutter-release
button and try again.
To save power when the flash is not in use,
press it gently downward until the latch
clicks into place.
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