Sony mvc-cd250 Operating Instructions Manual page 68

subject
is not in the center of the frame, you
can focus using the Focus range select mode
@WC-CD400) or the Center AF mode
(MVC-CD250). For example, when
shooting two human subjects with a gap
between them, the camera may focus on the
background visible through the gap. In
these cases, use AF lock to ensure the
subjects are in correct focus.
The camera
focuses
on the subject.
When the
AEfAF
lock indicator
changes from flashing to lighted up
and there is a beeping sound, the focus
adjustment is completed.
* AF lock lets you capture an image with the
correct focus even if the subject is at the edge of
the frame.