Nikon D5100 Reference Manual page 40

_I_ Using Autofocus in Live View
Autofocus is slower in live view and the monitor may brighten or darken while the camera
focuses. The camera may be unable to focus in the following situations:
• The subject contains lines parallel to the long edge of the frame
• The subject lacks contrast
• The subject in the focus point contains areas of sharply contrasting brightness, or the
subject is lit by spot lighting or by a neon sign or other light source that changes in
brightness
• Flicker or banding appears under fluorescent, mercury-vapor, sodium-vapor, or similar
lighting
• A cross (star) filter or other special filter is used
• The subject appears smaller than the focus point
• The subject is dominated by regular geometric patterns (e.g., blinds or a row of windows
in a skyscraper)
• The subject is moving
Note that the focus point may sometimes be displayed in green when the camera is unable
to focus.
[] Manual Focus
To focus in manual focus mode (_ 45), rotate the
lens focus ring until the subject is in focus.
To magnify the view in the monitor up to about 7.7 x
for precise focus, press the _ button. While the view
through the lens is zoomed in, a navigation window
will appear in a gray frame at the bottom right corner
of the display. Use the multi selector to scroll to
areas of the frame not visible in the monitor
(available only if _,0_ (Wide-area AF) or _;_(Normal-
area AF) is selected for AF-area mode), or press q[]
to zoom out.
1io
E
e_button
106
Navigation window