Nikon Z 50 Reference Manual page 441

Bokeh is irregular: With fast shutter speeds and/or fast lenses, you may
notice irregularities in how bokeh is shaped. The effect can be mitigated
by choosing slower shutter speeds and/or higher f-numbers.
Shooting ends unexpectedly or does not start: Shooting may end automatically
to prevent damage to the camera's internal circuits if the ambient
temperature is high or the camera has been used extensively for burst
shooting, movie recording, or the like. If you are unable to shoot because
the camera has overheated, wait for the internal circuits to cool and then
try again. Note that the camera may feel warm to the touch, but this does
not indicate a malfunction.
Image artifacts appear in the display during shooting: "Noise" (randomly-spaced
bright pixels, fog, or lines) and unexpected colors may appear if you
zoom in on the view through the lens. Randomly-spaced bright pixels,
fog, or bright spots may also arise as a result of increases in the
temperature of the camera's internal circuits during shooting; turn the
camera off when it is not in use. At high ISO sensitivities, noise may
become more noticeable in long exposures or in pictures recorded when
the camera temperature is elevated. Note that the distribution of noise
in the display may differ from that in the final picture. To reduce noise,
adjust settings such as ISO sensitivity, shutter speed, or Active
D-Lighting.
The camera cannot measure white balance: The subject is too dark or too bright.
Images cannot be selected as source for preset white balance: The images in
question were created with a different model of camera.
White balance bracketing is unavailable:
• An NEF (RAW) or NEF+JPEG image quality option is selected for image
quality.
• Multiple exposure or HDR (high dynamic range) photography is on.
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Troubleshooting