High scene contrast always creates difficulties for photographers, whether
shooting film or digital. The difficulty stems from the difference between the
ways the film or sensor "sees" and how the human eye sees. Our eyes
are adaptive, and can resolve large variations in brightness by the way it scans
throughout the scene and the amazing reflex of automatically restricting and
dilating the pupil to adjust to bright and dark areas before us. While light
metering systems in cameras are impressive in the way they can read light, the
fact remains that at the moment of exposure the lens on a camera records a scene
at one fixed aperture, or opening. In most situations this is no problem, as
the meter averages light values and the bright and dark areas are distributed
through the recording medium properly. But high contrast presents a problem.
better solution is to use the --1 contrast setting. This
allows for smoother tonal gradations and addresses the need to
control the divergent light values in this backlit scene.
All Photos © George Schaub, All Rights Reserved
The problem is the ability of the film or sensor to record within a certain
range of values, and when that range exceeds its capabilities some values, thus
picture information is lost. Some photographic mediums, such as negative film,
can handle a fairly wide range of those values. Slide films and digital sensors,
however, are less tolerant of widely diverse light values. At times a decision
must be made whether to sacrifice shadow or highlight detail. For the most part,
the best course is to bias exposure toward the highlights, or brighter areas
of the scene. Overexposed highlights in slide film yield little or no density,
and very bright areas, improperly recorded, become very harsh or do not record
any density at all. Overexposed highlights with digital sensors create similar
problems of "burnout" and getting any image information on a resultant
print is near impossible, or the corrections look false and artificial.
exposure was made at --1 exposure compensation. Note how
the highlights are better controlled but also how the shadow areas
become quite dark.
Fortunately, digital photographers do have some "outs" with this
problem. One is to work with the "contrast" setting on the digicam,
a programmable way to suppress contrast. The contrast settings are generally
found in the menu options, and may have a simple --1, normal and +1 setting,
or may be more complex with more steps. In essence, the --1 setting will
flatten the contrast curve of the recorded image, and may help overcome the
problem with harsh highlights in some scenes.
you come across a lighting situation such as this with you digicam
experiment with the contrast settings. Just to show you what a
+1 setting yields I've included this image. That's
obviously not the direction you want to take this.
One way around this is to make an exposure reading for the highlight, or brighter
areas. This suppresses, or controls the highlights better, so you can read more
detail in the leaves. But when you bias exposure for the highlights you are
suppressing all the tonal information, often driving down the shadow areas where
they can become too dark. This is how a slide film photographer would handle
Some digicams allow you to bracket contrast settings. You might want to work
with this feature in a number of lighting situations to get a handle on how
it can improve your results. Indeed, there are times when adding contrast, such
as on overcast days, can be helpful as well. In addition, a contrast "kick"
can also enliven colors.
photograph of some backlit leaves exhibits a typical high contrast
problem. As you gain experience you will be able to see the light
and immediately recognize when such lighting conditions will cause
a problem for your digicam.
Keep in mind that contrast bracketing is different than exposure bracketing,
the latter being a way to change how the light values themselves are being recorded
on the medium's recording scale. Contrast bracketing or correction is
a way to control high-contrast scenes, often without sacrificing the true sense
of light you perceived when you originally made the picture. It's a way
to help bring the sensor into line with the ways your eyes naturally adapted
to the light.