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New 11-area AF system. Adopting a refined version of Nikon's advanced Multi-
CAM 1000 AF Sensor Module (used in the D200), this new 11-area AF system adds new focusing options that assist in getting the desired shot. For example, while the system is able to use each of its 11 focus areas individually, the center sensor can also be switched to wide-frame operation for broader coverage. (Selected in the D80 Custom Settings Menu)
The D80 also features a new Auto-Area AF mode that measures from all 11 focus areas, automatically determines which of them are on the primary subject, and activates only those areas as a group. During AF measurement, the multiple AF points that are active will blink in the viewfinder. (Displayed when shutter release is half-pressed)
The three AF area modes that can be selected in the Nikon D80 Custom Settings Menu include:
1) Single Area AF: Focuses only on subjects in the selected area. Selection can be made from any one of the eleven AF spot sensors.
2) Dynamic Area AF: Focuses on subject in the selected area, but follows the subject if it moves from its original position, shifting automatically to the focus area into which the subject has moved.
3) Auto-area AF: automatically determines which of the AF areas are on the primary subject, and activates only those areas as a group.
http://www.digitalreview.ca/cams/NikonD80_intro.shtml