Basics of Flash Photography
Photography is all about light. These days, most digital cameras have an electronic flash unit built right into the camera body. The flash is designed to fire for a very short period of time and illuminate your scene in one of two ways:
- As the main source of light indoors or in the dark
- As a secondary source of light to fill in shadows when you’re shooting in bright light, such as outdoors
In general, your flash will probably know when to fire and can illuminate most pictures without your direct intervention. When your camera is set to the fully automatic exposure mode, the flash will probably come on as needed and not fire when it is not needed. On the other hand, you can probably figure out when you need a flash more effectively than your camera can. There will be situations when you may want your flash to fire when it would probably stay off, and vice versa. That’s why your camera has several flash modes to choose from. We’ll talk about those later in this & the following post.
Stay Within the Range of Your Flash
How far will the light from your flash travel? That’s something you need to know if you expect to get the most out of your flash. The flash built into most digital cameras is not extremely powerful; at best, you can expect to get a range of about 20 feet. To find the range of your camera’s flash, refer to the owner’s manual that came with your camera. You can almost always find the flash range listed in the specifications section of the manual. If you cannot find the range of your flash listed there, assume it is no more than about 15 feet.
The range of your flash also depends upon two other factors: the current ISO (light sensitivity) setting on your camera and the focal length setting of the zoom lens. The first factor—ISO—is pretty obvious. The more sensitive the CCD is made to light, the more effective the flash will be. It is an unfortunate side effect of zoom lens technology that when you increase the focal length to telephoto, you typically process less light than when you are using a wide angle or normal focal lengths. Since there’s less light getting through the lens barrel to the CCD at telephoto magnifications, the flash has less range.
If you’re used to the great range you would get from an external flash unit mounted on top of a 35mm SLR camera, you might be disappointed by the range from a digital camera flash. It stands to reason, though, that the small flash built into a digital camera could not have the same power as the large flash head—with lots of AA batteries—mounted on an SLR.
That means you’ll have to be aware of how far you’re trying to get the flash to throw light, especially at night or in very dark conditions. If your subject is very far away, such as 25 feet or more, it is unlikely that the built-in flash will have any effect at all on your photograph. Some digital cameras disable the flash automatically when they sense that the lens is focused on infinity. You might want to check your camera manual or experiment to see if that feature applies to your camera.
Getting Too Close
Believe it or not, it’s possible to get too close to your subject as well. Some digital camera flash units overexpose the subject when you are within a foot or two of that person or object. Since you know about the light-reducing properties of a telephoto lens, you might expect that you can get closer when you zoom in than if you are zoomed out. And you’d be right; with a typical camera, you cannot shoot any closer than about 3 feet when set on normal zoom, but you can shoot to within a single foot if you are zoomed in to telephoto.
Close-up photos are easy to overexpose if you leave the flash turned on. There are a few ways to work around this problem, depending upon what your flash unit is capable of doing:
Turn the flash off completely and shoot with natural light.
Bounce the flash off a plain white reflector, such as the ceiling or a reflector card. You’ll probably need an external flash unit to bounce, though.
Reduce the flash’s power setting to 50 percent or 25 percent.
Cover the flash with a tissue or gel (available at any camera shop) to reduce its intensity.
For many digital cameras, there’s an optimum range for your flash photographs. Try to stay between about 5 and 14 feet from your subject. Avoid using the flash in situations where the subject is more than about 15 feet away or closer than 3 feet.
