Nikon D40X - Manual (Page 40)

28 Reference: More on Photography (All Modes)/Focus
Manual Focus
Use this option when the camera is unable to focus correctly
using autofocus. To focus manually, select manual focus mode
and adjust the lens focusing ring until the image displayed on the
clear matte field in the viewfinder is in focus. Photographs can be
taken at any time, even when the image is not in focus.
When using a lens that offers A-M selection, select M when focusing manually. With lenses
that support M/A (autofocus with manual priority), focus can be adjusted manually with the
lens set to M or M/A. See the documentation provided with your lens for details.
Controls used
The Electronic Range Finder
If the lens has a maximum aperture of f/5.6 or faster, the viewfinder focus
indicator can be used to confirm whether the portion of the subject in
the selected focus area is in focus. After positioning the subject in the
active focus area, press the shutter-release button halfway and rotate the
lens focusing ring until the in-focus indicator (z) is displayed. Note that if
the subject is one for which autofocus does not perform well ( 27), the
in-focus indicator may be displayed when the subject is not in focus. Confirm that the image in the
viewfinder is in focus before shooting.
Focal Plane Position
To determine the distance between your subject and the camera, mea-
sure from the focal plane mark on the camera body. The distance
between the lens mounting flange and the focal plane is 46.5mm
(1.83in.).