A blast of flash can keep your snapshots sharp in the dark.
October 22, 2007
When you use your camera's built-in flash, or a dedicated shoe-mount accessory flash unit, the length of the exposure is determined by the duration of the flash itself rather than the camera's shutter.
|Since this electronic flash exposure varies from about 1/1000 sec to as little as 1/30,000 to 1/40,000 sec., using flash effectively eliminates blur due to camera shake, especially when shooting indoors or in the shade.
The default setting for most built-in flash units is "fire flash only when needed" so the flash will not fire unless the light level is fairly low. Virtually all digital cameras have a "fire flash for every shot" setting. You want this when there's too much light for the default flash to kick in.
A blast of light lets you use a smaller aperture, improving depth of field and overall sharpness, while eliminating shake. Photo by Mason Resnick
Using flash to stop subject motion and camera shake works best with an accessory flash rather than a built-in flash because these larger units have more power (light output) which enables them to act as the primary light source even in fairly bright light.