A2: Center Focus Point; A3: Built-In Af-Assist Illuminator - Nikon D90 User Manual

a2: Center Focus Point

This option (available in all shooting modes) determines the size of the center focus
point.
Option
Normal zone
c
(default)
7 Wide zone
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
If the subject is poorly lit, the AF-assist illuminator will light to assist the focus
operation in single-servo AF (AF-S selected for autofocus mode, or single-servo AF
On
selected in AF-A autofocus 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.
The AF-assist illuminator does not light to assist the focus operation. The camera
Off
L
may not be able to focus using autofocus when lighting is poor.
A
The 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.
A
See Also
See page 231 for restrictions on the lenses that can be used with AF assist.
174
Viewfinder display
Focus on stationary subjects that can be easily framed
in the focus point.
Focus on moving subjects. Not available when Auto-
area is selected for Custom Setting a1 (AF-area
mode).
Description
Description