Nikon D5100 Experience - Locking Focus

Nikon D5100 Experience
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only track the subject as long as it is positioned at the selected AF point, and it will not be
tracked laterally to the other, surrounding points. As noted above, the single AF point you select
will track a subject if it moves closer or farther away, but the AF system will not track the
subject if it moves left, right, up, or down and away from your selected AF point. To do this,
you use Dynamic-Area AF mode or 3D-Tracking mode.
Dynamic-Area AF
With Dynamic-Area AF Mode, you select an AF point and if your moving subject moves away
from that point to a surrounding neighboring point, the camera will track it and continue to focus
on it. Select this option when you are tracking and photographing moving subjects using
Continuous-Servo AF (AF-C) or Auto-Servo AF (AF-A).
3D-Tracking
This mode is used for subjects moving erratically from side-to-side in the frame, and are tracked
by areas of color. You may select this option when you are tracking and photographing moving
subjects using Continuous-Servo AF (AF-C) or Auto-Servo AF (AF-A). Again, you choose the
initial AF point to locate the subject and begin the tracking. If the area of color you wish to track
is too small or if it blends into the background, this mode might not be very effective.
Auto-Area AF
The camera uses all 11 AF points to detect what it thinks is the subject and automatically choose
the appropriate AF point(s). Typically, the camera will select the nearest subject or a human in
the frame, so it may not focus on exactly what you wish to focus on. That is why it is best to use
one of the other modes and select the AF point yourself. However in certain situations such as
quick sports or action scenes you may have to make use of this.
Checking Focus: You can review your images on the rear LCD Monitor of your D5100 to try to
determine if they are in focus, especially by zooming in as close as possible. But be aware that
this screen has less than one million dots or pixels, while your actual image has about 16 million
pixels. That means that many images will appear to be in proper focus on your LCD screen, but
you might discover that the actual images are not really as clearly in focus when you view them
full size on your computer monitor.
Locking Focus
As I began to discuss in the Custom Settings section you can lock the focus, independent of
locking the exposure. I suggested you set up the camera so that a half-press of the Shutter-
Release Button locks focus and the AE-L/AF-L Button locks exposure (see Figure 22). In AF-S
Autofocus Mode, press and hold the Shutter-Release Button half-way to lock focus at the current
distance determined by the active AF point. As long as you continue to hold the Shutter-Release
Button half-pressed, the focus distance will not change even if your subject moves or you
recompose the shot. However, in AF-C and AF-A Autofocus modes, this will not work because
holding the Shutter-Release Button at half-press tells the camera to continuously track the
subject as it moves nearer and farther from the camera. So you will need to use another method
to lock focus if you desire. Or other situations might call for the need to lock focus and exposure