Nikon D750 User Manual page 101

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Power Aperture
Power aperture is not available with some lenses. Power aperture is
available only in modes A and M and can not be used while photo
shooting info is displayed (a 6 icon indicates that power aperture can
not be used).
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Using an External Microphone
The optional stereo microphone can be used to record sound in stereo
or to avoid recording focus noise and other sounds made by the lens
(0 443).
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Headphones
Third-party headphones can be used. Note that high sound levels may
result in high volume; particular care should be taken when
headphones are used.
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See Also
For information on assigning power aperture to the Fn and Pv buttons,
see Custom Settings g1 (Assign Fn button, 0 370) and g2 (Assign
preview button, 0 372). The Fn button can be used to widen the
aperture, the Pv button to narrow the aperture.
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