Nikon D750 User Manual page 493

Can not select focus point:
• Unlock focus selector lock (0 127).
• Auto-area AF or face-priority AF selected for AF-area mode: choose
another mode.
• Camera is in playback mode (0 241) or menus are in use (0 292).
• Press shutter-release button halfway to start standby timer (0 39).
Can not select AF mode: Manual focus selected (0 60, 132).
Can not select AF-area mode: Manual focus selected (0 60, 132).
Only one shot taken each time shutter-release button is pressed in continuous release
mode: Continuous shooting is not available if built-in flash fires (0 184).
Image size can not be changed: Image quality set to NEF (RAW) (0 115).
Camera is slow to record photos: Turn long exposure noise reduction off
(0 317).
Noise (bright spots, randomly-spaced bright pixels, fog, or lines) appear in photos:
• Choose lower ISO sensitivity or use high ISO noise reduction (0 134,
317).
• Shutter speed is slower than 1 s: use long exposure noise reduction
(0 317).
• Turn Active D-Lighting off to avoid heightening the effects of noise
(0 175).
AF-assist illuminator does not light:
• AF-assist illuminator does not light if AF-C is selected for autofocus
mode (0 121) or if continuous-servo autofocus is selected when the
camera is in AF-A mode. Choose AF-S. If an option other than auto-area
AF is selected for AF-area mode, select center focus point (0 123, 127).
• The camera is currently in live view or a movie is being recorded.
• Off is selected for Custom Setting a9 (Built-in AF-assist illuminator)
(0 332).
• Illuminator has turned off automatically. Illuminator may become hot
with continued use; wait for it to cool down.
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