Though most of us tend to think of flash as something to be used indoors in dim lighting, in fact, one of the best times to use flash is when you're taking informal portraits outdoors. Outdoor portraits are nice because there's a lot of available light and also, it's easier to find a simple and attractive background. The problem with shooting in portraits in sunlight is that the sunlight often creates a lot of dark shadows in eye sockets and under chins and noses.
The solution is very simple: just turn on the flash. Most digital cameras will automatically adjust the exposure between the flash and the existing light and create a very pleasing balance. This "fill flash" provides just enough flash to prevent dark shadows while still exposing for the ambient (daylight) correctly. And I have to tell you that automatic fill-flash is a genuine miracle of simplicity compared to the calculations and math that I had to perfom with the manual accessory flash units that I used when I was learning photography.
By comparison built-in flash is totally simple to use. I shot the portrait here using my Nikon D70s's built-in flash and didn't even look at the exposure settings! I trusted the camera to create a good balance between flash and daylight and it did. I also intentionally placed the light behind the two young woman so that they wouldn't be squinting into the light. I knew that because I was working within the distance limitations of the flash, the flash would provide enough light to correctly fill the shadows.
If you are using a DSLR with an accessory flash you'll have even more control over the balance between the flash and ambient exposures. Most flash units will let you set the exact flash-to-daylight ratio, increasing or decreasing flash power as needed. If the skin tones are coming out a tad too light at -1 stop flash exposure, for example, you could switch to -1.5 stops of flash exposure and just tone down the flash a bit. Your flash manual will explain the use of fill-flash in greater detail.
Next time you're taking portraits outdoors, turn the flash on and see if you don't like the exposures much more. Your subjects will be a lot happier without all of those dark shadows and because they'll no longer have to squint into the sunlight.
3 days ago