Creating better outdoor portraits can be easy if you use a simple two light setup. Just use your shoe mount strobe as one light plus the sun as your second light.
Studio photographers know that using multiple light sources can help produce more flattering and natural looking portraits. While most studio setups call for three or four lights, two lights can make for a good start for the beginner. This article tells you how.
Combining the two light sources
Making available light work to your advantage is am important skill for a photographer. Sometimes though, finding ways to compliment available light with supplemental flash can make for even stronger photos. One reasonably simple trick is to combine sunlight and a shoe mount flash to produce a multi-light portrait when shooting outdoors. The idea is to position your subject so the sun lights one side of your subject while the strobe lights the other. You can do this with the flash on camera and the sun to one side, but a better method is to get the flash off camera so both lights can be positioned at 45-degree angles to the subject. Do this by putting the sun to the subject's front quarter and the flash to the other front quarter. The trick here is to manage the exposure properly. First get the right exposure for the available light with an appropriate shutter speed (somewhere between 1/60th and 1/250th depending on your camera's flash sync speed). Then dial up the power on your camera's flash to match the aperture setting for the exposure settings you've chosen. This will give you what's known as "flat" or even lighting. For even better results, set your flash for about an f-stop below the available light setting in order to produce light with a bit more character. Go even lower (2 full f-stops) and get "Rembrandt" lighting with its characteristic triangle of light over one cheek.
Of course as you get more comfortable with the technique, you can look at adding useful accessories to your arsenal. Some examples include wireless flash operation, a portable light stand and even a good quality soft box for better light quality. If you're on a tight budget or are reluctant to spend a lot on off camera flash, you do have some workable options. One easy choice is an off-camera shoe cord that will get your flash a couple of feet off camera (you can hold the camera with one hand and the flash with the other). Depending on your flash, you may also be able to use a cheaper PC cable to get the flash farther away (at the loss of TTL exposure) and held by a friend or mounted on a tripod or light stand.