Nikon D2HS - Manual (Page 94)

80
Taking Photographs—Focus
Getting Good Results with Autofocus
Autofocus does not perform well under the conditions listed below. If the
camera is unable to focus using autofocus, use manual focus
81) or use
focus lock ( 78) to focus on another subject at the same distance and then
recompose the photograph.
AF-Assist Illuminators
If the subject is dark, a Speedlight with an AF-assist illuminator can be used to assist
the autofocus.