Contrast is the difference in brightness between light and dark areas in a scene and can be a function of the subject matter, lighting conditions, or a little of each. Controlling contrast in camera can be a challenge.
At the simplest levels using a lower ISO setting will slightly increase contrast, while higher ISO setting will usually decrease contrast.
Other in-camera techniques can be found in your digital camera's menus. Olympus, for example, offers several Picture Modes, including Natural and Vivid. The Natural setting produces "natural colors" i.e., less contrast. The Vivid mode creates "vivid colors," and along the way greater contrast.
As with many other manufacturer's digital SLRs, you can fine-tune image parameters such as contrast, for any of Olympus' Pictures Mode and these adjustments are recorded in each picture effect mode.
Olympus' Shadow Adjustment Technology (SAT) available on several models, including the E-420, allows you to capture greater detail in the shadows while maintaining detail in the highlights. Shadow Adjustment is part of the camera's Gradation menu option. When the weird little infinity symbol is displayed, Gradation is set for normal. When both the infinity symbol and the word AUTO are displayed, SAT is active.
If there is no shadow control in your SLR, as with the Canon EOS 5D shows but you can use the Contrast controls to lower the contrast and “open up” the shadows to reveal more detail. The downside is that sensor noise is more likely found in shadow areas than mid-tones.
Joe Farace is co-author of “Better Digital Available Light Photography” along with Pulitzer Prize winning photographer Barry Staver. It is published by Focal Press and is available in all the best bookstores, including Barnes & Noble and Amazon.com.