Exposing Shadows
Contrasty shadow scenes can fool reflected light meters, such as those built into cameras. A spot meter enables you to meter the most important highlight area, and determine an exposure that will give detail there (try two stops more exposure than the highlight reading calls for). It's generally fine to let the shadows go black; if you want detail there, too, you'll probably need to use the Zone System--or Photoshop's Shadow/ Highlight feature. With the multi-segment meters built into today's SLRs, you'll have to experiment to see how your specific camera handles shadow scenes--with some scenes, multi-segment meters work very well, with others they don't.
It's a good idea to bracket exposures when you start doing shadow images.
1: Shadows Add Impact
Soft light is easy to work with, primarily because it produces soft shadows. If you didn't get the main light in the right place, there are no harsh shadows to whump the viewer upside the head with that fact. But soft light also lacks impact. Harsh shadows--in the right place(s)--can add impact and drama to a photograph. The best source of harsh shadows is direct sunlight outdoors. But you can create strong shadows with direct light sources in the studio, too, such as direct electronic flash or tungsten lamps.
The contrast between sunlit fog and unlit trees adds drama to this early-morning scene.
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2: Show The Subject A Different Way
For a different sort of image, make the shadow the main subject of the photo, or photograph only the shadow, without including the subject.
This self-portrait was "discovered" on the side of a store near the end of a hike. Keep your eyes open for such photo ops in your wanderings.
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3: Get Artsy
Hey, nothing says you can't use shadows as graphic elements. Instead of grumbling when you encounter harsh shadows in available light scenes, try to work with them.
Existing shadows can provide lots of photo ops, once you become attuned to them. Look for interesting shadow patterns next time you're out searching for things to photograph.
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4: Silhouettes
Silhouettes offer another opportunity to use shadows. A silhouette is a shadow--an unlit subject. Thus, silhouettes work best when the subject is readily identifiable by its shape; subjects primarily noted for their texture or detail are not good choices for silhouettes.
Bird watchers will immediately recognize these silhouettes as great-tailed grackles, by their shapes and poses. Others might simply enjoy the overall picture.
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5: Leading Lines
Shooting outdoors early or late in the day, you can use the long shadows produced by the low-angle sun to lead the viewer's eye into the photo.
Shadows extending toward the camera can create leading lines, too.
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Penumbra?
Shadows are more than just black blobs that mimic the shapes of things casting them. At the center, known as the umbra, the shadow is very dark indeed. But at the edges is a lighter, softer-edged area called the penumbra. When conditions are right, you can record this in a photograph of the shadow. (If the light source creating the shadow is a true point source, there will be no penumbra. But few true point light sources exist in our daily lives.)
Soft Vs. Hard Light
Soft light is produced by light sources that are large relative to the size of the subject, such as an overcast sky. Hard light is produced by light sources that are small compared to the size of the subject, such as direct electronic flash. The sun is huge, but so far from the Earth that it acts as a hard light source. Hard light produces the best shadows for photos.
How Long?
Outdoors, the lower the sun is in the sky, the longer the shadows objects here on Earth will cast. A six-foot person will cast a six-foot shadow when the sun is at a 45° angle to it. When the sun is lower in the sky, the shadow will be longer; when the sun is nearly overhead, the shadow will be very short.
How Sharp?
The closer the object casting the shadow is to the surface upon which it is casting the shadow, the sharper the shadow will be. An airplane flying high overhead will cast a shadow so fuzzy you might not even notice it, while an object just a foot above the ground will cast a very sharp shadow.
Source: http://www.shutterbug.com
