you use a compact digital camera, you usually look at the monitor when
taking a picture. Some cameras do not have optical viewfinders that are
available on conventional film cameras. A monitor allows you to
accurately frame your pictures and is convenient because of the various
information that it displays. However, it may be difficult to see the
monitor when outdoors on a sunny day because of the surrounding light.
Not only is framing the picture difficult, it is also hard to determine
the right level of exposure. A histogram can be an effective way to
determine the exposure when it is difficult to see the monitor. A
histogram displays the distribution of light in the subject that is
framed, and is a convenient tool for determining the exposure in
bright, outdoor locations. Unlike the exposure meter, a histogram
displays the light distribution. You may need some time to get used to
using a histogram, but once you do, it can be very convenient.
Let's look at a histogram
at correct exposure: The histogram graph is not touching the left or
right border, and no part of the picture is black-crushed
(underexposed) or white-clipped (overexposed).
using +1.0 exposure compensation: The histogram graph is touching the
right border. In the picture, the white flower is white-clipped
(overexposed), resulting in burnt-out highlight details.