Nikon D90 user manual A2 Center Focus Point, A3 Built-in AF-assist Illuminator, 174

a2: Center Focus Point

This option (available in all shooting modes) determines the size of the center focus point.

	Option	Viewfinder display	Description
c	Normal zone		Focus on stationary subjects that can be easily framed
	(default)		in the focus point.
			Focus on moving subjects. Not available when Auto-
7 Wide zone			area is selected for Custom Setting a1 (AF-area
			mode).

See page 54 for more information on focus settings.

a3: Built-in AF-assist Illuminator

Choose whether the built-in AF-assist illuminator lights to assist the focus operation when lighting is poor. This option is available in all shooting modes except l and m.

	Option	Description
		If the subject is poorly lit, the AF-assist illuminator will light to assist the focus
	On	operation in single-servo AF (AF-Sselected for autofocus mode, or single-servo AF
		selected in AF-Aautofocus mode) when Single point, Auto-area, or 3D-tracking
	(default)
		(11 points) is selected for Custom Setting a1 (AF-area mode) or when Custom
		Setting a1 is set to Dynamic area and the center focus point is selected.
L	Off	The AF-assist illuminator does not light to assist the focus operation. The camera
		may not be able to focus using autofocus when lighting is poor.

AThe AF-Assist Illuminator

The AF-assist illuminator has a range of about 0.5–3.0 m (1 ft. 8 in.–9 ft. 10 in.); when using the illuminator, use a lens with a focal length of 24–200 mm and remove the lens hood.

ASee Also

See page 231 for restrictions on the lenses that can be used with AF assist.

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