It seems a little odd switching the flash on in bright sunlight but it’s one of the best times to do it. Those heavy shadows cast on your subjects face (particularly under the eyes) by the midday sun can be a thing of the past with a little extra light from your camera’s popup flash.
Many cameras will allow you to control the intensity of the flash output with their flash compensation function so don’t be satisfied with your first shot – dial it up or back a little once you’ve taken a first test shot until you get a nice natural light.
The bonus of using a little fill flash is that it will often darken your background a little which can give your shot a little more punch and make your subject stand out a little from their background. Fill flash will also create a little catchlight in the eyes of your subject, giving their eyes that little extra sparkle!
Sometimes using fill flash will also allow you to shoot with the sun behind your subject – this means their face has no direct sunlight on them but that they have a little back light falling upon their hair and shoulders which can create a nice impact.