If you've purchased a camera recently, it most likely came with a built-in flash. A camera's built-in flash can be a valuable asset to enhance your photographs, but it's not without its limitations. However, by using the flash mindfully you can avoid the pitfalls often encountered when using this tool.
Most cameras have a setting to automatically trigger the flash whenever the internal light meter detects that there isn't enough light to take a picture at the correct exposure. You can change the settings in your camera so that the flash will stay on for every exposure or, alternately, will stay off for every exposure. Whichever setting you choose, the greatest asset of the built-in flash is its quick accessibility.
Since this flash is so close to the camera body, one of the drawbacks of using it is the likelihood of human subjects appearing to having red, glowing eyes. Such red-eye effects are due to the light of the flash traveling faster than the pupil can adjust to the temporary change in light (i.e., the flash burst) thus resulting in the flash's light reflecting the color of the veins and other parts inside the eyeball. However, cameras often come with a function known as red-eye reduction, which causes the flash to strobe quickly before the camera takes the picture. By delaying the moment when the image is captured, the red-eye reduction feature allows the eyes' pupils to adjust to the flash and thus prevent the red-eye effect.
Another limitation of the built-in flash concerns the lack of control over the intensity of the flash. The maximum distance that the flash can probably be used successfully is twelve to fifteen feet, depending on the ambient light. However, getting too close can be equally damaging to your photo as the power of the flash will create a washed out or bleached effect in your pictures. One great way to weaken the flash and help the light in your pictures appear more natural is to cover the flash with a piece of a paper towel or similar material. The paper will diffuse the flash and minimize the sharpness of shadows behind your subjects as well as keep any part of your photo from being too overexposed. Diffusing the flash in this way can also guard against the red-eye effect.