Using Fill Flash
Click to explore fill flash.
Fill flash illuminates this backlit sunflower against the sky. If flash hadn't been used, the flower would have had dark shadow areas.
The almost universally accepted fill flash icon.
When photographing people or other subjects with the light to the side,shadow areas can be so dark in the image that they show little or no detail. When the subject is backlit or against a bright background, it can be underexposed. To fix these problems you use fill flash—often called Flash On or Forced Flash. When using this setting, the flash fires even if there is enough available light to take the picture without flash. Fill flash is also a good way to get accurate color balance under unusual lighting.
With no fill flash (left) the bright background has caused the main subject to be underexposed. Using fill flash (right), the subject is properly exposed. Photo courtesy of Tim Connor.
One reason to use fill flash outdoors is to add catch lights to eyes—hot spots that make the eyes sparkle.