camera itself.Using RGB histograms allows us to tell at a glance whether
the photo we just shot is exposed properly for our purposes
or whether it is too dark or too light. Histograms make it
clear whether we have a lot of clipping going on which
means we have lost photo information that can’t be retrieved
later in Photoshop or other post- processing software. This
is something we really need to know because if I spend an
hour shooting an important subject only to find out later that
all images were severely overexposed, it is a heartbreaker if
I can’t repeat the shoot due to circumstances, etc.
This is not the place to explain how best to use histograms. There
are dozens of good tutorials on using histograms on the web. Just
note: when shopping for a camera, get one that does show you an
RGB histogram. Ideally the histogram graph should have a color
display with one graph each for red, blue, and green all displayed
on the same screen. Given this, you can see instantly if any of the
colors have overflowed to the right which suggests clipping and the
loss of important photograph information.
Note that most in-camera histograms use the internal .JPG and
not the raw image for their calculation. While there is not usually
that much difference between the two, it is something to be
aware of. Since I use only the manual program mode and don’t
use automatic focus, shutter, or aperture modes, I would be lost
without histograms. Read more about histograms here:
http://www.bythom.com/histogram.htm