Troubleshooting; Battery/Display - Nikon D750 User Manual

Troubleshooting

If the camera fails to function as expected, check the list of
common problems below before consulting your retailer or
Nikon-authorized service representative.

Battery/Display

The camera is on but does not respond: Wait for recording to end. If the
problem persists, turn the camera off. If the camera does not turn off,
remove and reinsert the battery or, if you are using an AC adapter,
disconnect and reconnect the AC adapter. Note that although any data
currently being recorded will be lost, data that have already been
recorded will not be affected by removing or disconnecting the power
source.
Viewfinder is out of focus: Adjust viewfinder focus (0 29). If this does not
correct the problem, select single-servo autofocus (AF-S; 0 121), single-
point AF (0 123), and the center focus point (0 127), and then frame a
high-contrast subject in the center focus point and press the shutter-
release button halfway to focus the camera. With the camera in focus,
use the diopter adjustment control to bring the subject into clear focus
in the viewfinder. If necessary, viewfinder focus can be further adjusted
using optional corrective lenses (0 443).
Viewfinder is dark: Insert a fully-charged battery (0 25, 30).
Displays turn off without warning: Choose longer delays for Custom Setting
c2 (Standby timer) or c4 (Monitor off delay) (0 336, 337).
Control panel and viewfinder displays are unresponsive and dim: The response
times and brightness of these displays vary with temperature.
Fine lines are visible around active focus point or display turns red when focus point is
highlighted: These phenomena are normal for this type of viewfinder and
do not indicate a malfunction.
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