If
your camcorder has an automatic focus control (often
called autofocus), you can skip this page, right? Well,
not really. Like automatic exposure, autofocus works
well most of the time, but not all the time. When should
you override it and use the manual focus control? To
answer that, you need to understand the basics of how
autofocus works.
Think
bats. We all learned in grade school that bats can't
see worth a darn. Instead, they send out a radar-like
signal which bounces off houses and trees and then returns
to the bats to help them navigate. This is also how
autofocus works on your camcorder. An invisible signal
is sent out; it bounces off your grandma; and then returns
to the camcorder with information on just how far away
she is. Then the autofocus control on your camcorder
adjusts accordingly.
This animation simulates
the problem with autofocus. In a
word: it hunts. In this case, the
autofocus isn't sure if should focus
on the funny-looking guy OR the
background. So it shifts back and
forth. Very annoying.
The
trouble is, your camcorder doesn't know what Grandma
looks like. It might think that Rover, sitting behind
Grandma, IS Grandma. If this happens, the autofocus
control would put Rover in focus, making Grandma out
of focus.
An
equally annoying trait of many autofocus controls is
to get confused and rapidly change focus every second
or so (Grandma-Rover-Grandma-Rover....)
The
only real solution to these problems is to switch OFF
the autofocus, and control your camcorder focus manually.
(Most camcorders have a switch for this. Look on the
lens.) You can then set the focus to Grandma and NOT
Rover.
It
may be helpful to know that professional camera operators
NEVER use autofocus. Never. I am not suggesting that
you avoid your autofocus feature; just be ready and
able to turn it off if the situation arises.
