Use Fill Flash
Fill flash has been a wedding photographer’s secret weapon for years. Think you don’t need a flash on a bright sunny day? Think again! Even in (or because of) situations where there’s a great deal of light in the background, your photos can have a greater impact if you use the flash in “fill” mode.
Bright sunlight can cause deep, unflattering shadows under the eyes and other facial features, especially if the sun is directly overhead (as discussed in Beginning Photography Tip). Also, If the background is really bright, say if you’re shooting against the sun during sunset, the camera will adjust the exposure for it and your subject will end up in near darkness, possibly even in silhouette.
When you set your flash to “fill” mode (consult your manual for your camera’s actual setting), the camera exposes for the background first, then adds just enough light to expose your subject in front of it.
The result is a professional-looking shot where everything is lit beautifully. This is also a great way to get a good portrait without having the subject squint from the harsh sunlight.
The caveat to this is you should know the effective range of your flash. Most built-in flashes have a range of about 10 feet or less—probably closer to something like 6-8 feet.
Don’t step too far back from your subject. Your manual probably has the specifications of your flash, but even so, it’s best to practice and look at your results. After a few shots, you’ll get a feel for what your optimum distance is.
Try this on a bright sunny day: bring your subject into an open shade (to avoid harsh shadows—perhaps beneath a tree) with a bright background, turn on your fill flash and shoot. Move back and forth a few feet to see how the results change.
After you’re comfortable using the flash this way, there are many variations to play with. Try positioning your subject with a sunset in the background, or reflecting off a surface like the ocean at the beach.
This would normally cause the subject to darkening into a silhouette because the sun is so bright, but using the flash, the whole scene should be illuminated correctly. Also, try positioning the subject so that the sun illuminates the hair from the back. Do it from the right angle and you can create a halo effect around the hair.