Nikon D100 - Manual (Page 79)

Taking Photographs—Focus
Controlling How the Camera Focuses
67
Closest Subject Priority (Dynamic Area AF)
Dynamic-area AF can be combined with closest subject priority. When this
option is in effect, the focus area can not be selected manually, and no focus-
area indicators are shown in the viewfinder or control panel. Instead, the
camera automatically chooses the focus area containing the subject closest to
the camera and focuses on this subject when the shutter-release button is
pressed halfway. Note that the camera may be unable to select the focus area
containing the subject closest to the camera when a telephoto lens is used or
your subject is poorly lit. Single-area AF is recommended in these cases.
20—Dyn. AF AF-S ( 157)
To enable closest-subject priority when dynamic area AF is selected in single-servo AF,
select Select AF Area for Custom Setting 20 (Dyn AF AF-S).
21—Dyn. AF AF-C ( 157)
To enable closest-subject priority when dynamic area AF is selected in continuous-servo
AF, select Select AF Area for Custom Setting 21 (Dyn AF AF-C).