Nikon Z 9 Reference Manual page 140

D
Long Time-Exposures
•
Note that "noise" (bright spots, randomly-spaced bright pixels or fog) may
be present in long exposures.
•
Bright spots and fog can be reduced by choosing [ON] for [Long exposure
NR] in the photo shooting menu.
•
Nikon recommends using a fully-charged battery, the supplied charging
AC adapter, or an optional AC adapter and power connector to prevent
loss of power during long exposures.
•
To prevent blur, use of a tripod or a device such as an optional remote cord
or wireless remote controller is recommended.
Exposure
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