Basics of Flash Photography

Almost every digital camera made today—with the exception of very inexpensive VGA-resolution cameras—comes with a built-in flash unit. The flash is a way to bring extra light with you and brighten many kinds of pictures. On the other hand, I have found that most people don’t really know how to take advantage of the flash that is built into their camera, so in this chapter I discuss techniques like fill flash, red eye reduction, and bounce flash. Lighting isn’t just about using a flash, either. You can use a reflector to spread light around for a more pleasing effect, and play with the white balance built into your camera for better lighting control as well.

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:
1) As the main source of light indoors or in the dark
2) 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.

Flash Modes

(note: Difference camera brand may difference sign modes)
In this digital age, “on” and “off” are just too easy. Instead, your camera’s flash has three or more modes, each intended for a specific photographic situation. Here’s the rundown of your options. Your camera may not include all of these features, so you might want to check out your camera manual before you get your heart set on trying all of them out. Your camera should have some, if not all, of these modes:

• Off This one is easy. When you set your camera to this mode, no matter how strongly your camera believes that you need extra light, the flash will not fire. This is handy for situations where you are not allowed to fire a flash, such as in a church or a museum, or when you’re too close to the subject and think you might overexpose it. You may also want to turn off the flash in many night photography situations.


• Auto This is the standard mode that you’ll probably want to leave your flash in most of the time. When set to auto, the flash determines whether it needs to fire based on the amount of light in the scene. This is a good mode to use when you don’t want to think about whether the flash needs to fire. For typical snapshot photography, just set your flash to auto.


• Forced This mode goes by many different names depending upon the camera you are using. Sometimes called “forced flash,” “fill flash,” or just “on,” forced flash is probably the most appropriate name. When you set your camera’s flash to this mode, it will fire regardless of how much light is available. Why would you want to use this mode? It’s most useful as a fill flash: when you’re shooting outdoors in natural light, the fill flash can erase shadows that would appear based on the way the sun hits your subject. Fill flash, or forced flash, is great for portraits.


• Red eye Red eye reduction mode has become extremely popular in all sorts of cameras, both digital and analog. By pre-flashing the camera flash several times quickly right before the picture is taken, the red eye reduction mode forces your subject’s pupils to close down to a smaller size, thus decreasing the chances that they will reflect the light of the flash. When you use this mode, remember that it will take a fraction of a second longer for the picture to be taken; don’t pull the camera away as soon as you press the shutter release, or you’ll blur the picture. If you’re photographing people in a dark room, however, this mode is probably worth the extra time. You do not need to use red eye reduction outdoors or in bright light.


• Low power Some digital cameras let you control the power output of the flash. You might be able to reduce its intensity by 50 percent or more. You can use this mode when you are using the flash to fill in shadows, or when you are taking a close-up and a full flash burst would overexpose your subject.


• Slow In the world of 35mm photography, this slow setting is sometimes referred to as a rear curtain flash. Other cameras, such as Nikon digitals, call it Slow Sync. Of course, that name may not help you understand what the slow setting does. When you set the camera to slow flash, it fires the flash at the tail end of the exposure. It’s used most often at night, when the exposure is long (such as a second or more). What does it do? Suppose you were trying to take a picture of a car driving down the street. With an ordinary flash exposure, the flash fires right away, thus freezing the car at the start of the frame. In a long exposure, you will then see headlights cut through the car and out of the frame. The slow mode, however, saves the flash for the end. In a picture taken with this mode, you will see headlights that travel through the frame and then meet up with the rear of a flash-frozen car. The car is leaving the picture at the end of the exposure, just like it should. As you can imagine, you won’t use this mode all the time, but it is indispensable when you need to get a certain kind of long-exposure photograph.

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.
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  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.
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  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.
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  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. In fact, 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.

Flash: 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:
1) Turn the flash off completely and shoot with natural light.
2) 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.
3) Reduce the flash’s power setting to 50 percent or 25 percent.
4) Cover the flash with a tissue or gel (available at any camera shop) to reduce its intensity.

=TIP=
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.