40 Better Available Light Digital Photography
Is there really a perfect exposure? Showing a photograph to a
group of ten photographers will yield ten different answers about
its exposure. One person may favor a high key print, whereas
another might like to see good detail in the light areas. A third
photographer may like a print with equal tonality across its
dynamic range. Enter one of the most useful features of digital
photography: the histogram.Meet the histogram
What’s this histogram, where do we fi nd it, and how do we use
it to our advantage? The histogram is a graph showing the tonal-
ity range of the photograph. It shows us all of the values, or
levels of brightness, from black through the mid-tones to white—
and, most importantly shows us any values that go beyond.
It will display on the camera’s LCD screen (you will need to
set it up once, through the camera’s menu system), and can be
displayed in most image-browsing and image-manipulation
software. This discussion rests with the camera’s histogram,
assuming that it’s being reviewed during the photography
session, where exposure adjustments can be made on the spot.
Once the images are downloaded to your computer, it’s usually
too late for retakes if exposure isn’t correct.
Most cameras offer two histogram settings: one for exposure, and
the other for color. We’ll concentrate on setting it for exposure,
because that histogram tells us the amount of lightness, darkness,
and middle tones that have been captured—and, most impor-
tantly, lets us know if these values are within an acceptable range.
An important concept to understand is the difference between
what the human eye “sees” and what a camera/lens/image sensor
can record. As photographers, if our photography is to be suc-
cessful, we must learn to see as the camera sees. Our eyes can see
a very broad range of tonality, from light to dark, because the iris
adjusts continually, in microseconds, to changes in light and
focus. The camera and lens cannot do this. Their tonal range is
limited, as is the tonal range of our output (photographic prints,
Web display, the printed page), and the histogram tells us if our
images are within an acceptable range or not.
Another very useful exposure tool within your camera is the
blinking highlights feature. Barry calls them blinkies, and some
people call them “marching ants,” and Joe thinks they are just
annoying, but that’s just him. You may be familiar with those
terms from Selection modes in imaging software. As you high-
light an area to work on it, the blinking dashes outline that area.
The same thing holds true on the LCD screen of your camera.
When something is selected, the areas in your image that are out
of range on the highlight side are outlined with the marching
ants. Even on the small LCD screens, the overexposed areas are