Digital Photography Basics: Using a Flash

Some people leave the flash on all the time, but that means it'll sometimes fire when you don't want it to. Other people turn the flash off completely and never use it. I land somewhere in the middle: I tend to leave the flash turned off most of the time, but I switch it on when the occasion warrants. Your camera probably warns you with an icon in the viewfinder (like the one in the lower-left corner of this viewfinder image) when the light is too low for a good photo without the flash; check your manual to learn what your camera's icons mean. You can also check what shutter speed the camera is trying to use; anything under 1/60 second is probably too slow. Either increase the ISO (which will increase the sensitivity of the sensor), or turn on the flash.

Your camera flash probably has more settings beyond just on and off. Check out "Master Your Camera's Flash Modes" for a primer on how to use your flash's various modes. You should know when to switch to fill flash, which is great for avoiding harsh shadows when taking pictures of people outdoors in direct sunlight; I took the photo on the left without any flash, and used my fill flash for the photo on the right. You should also know how to use red-eye reduction indoors in low light, whether you're shooting pictures of people or animals. (Read "Photographing Your Pets" for more on that if you're interested.)

Your camera's built-in flash has a very limited range: In most cases it'll illuminate subjects only up to about 10 feet away from your camera. If you need to shoot across longer distances--like a school auditorium, for example--consider adding an external flash to extend your range to 30, 40, or even 50 feet. Check your camera to see if it has a hot-shoe attachment like the one you see here. Even some point-and-shoot cameras can accommodate external flashes via a hot shoe. You can also do stuff with an external flash that you can't do with the built-in flash--like bouncing the light.

The harsh light you get from direct flash illumination can make photos look like police mugshots. If you're using an external flash, you can bounce the light to soften your photos. Try bouncing the light off the ceiling, or using a bounce card that diffuses the light from your flash. You can buy a bounce card or make one yourself--or you could choose a higher-end option and spring for a Rogue FlashBender ($40), shown here. You can use this reflective, bendable screen like a traditional bounce card, angling it to direct the light to one side of the scene or even rolling it to direct light into a tight beam. FlashBenders are intended for digital SLRs with external flash heads.

You'll definitely need an external flash to take a picture of a large scene. Don't mount it on the camera--just turn it on and hold it in your hand. (It doesn't even need to be compatible with the camera.) Set the camera on a tripod and configure it for a long exposure, such as 30 seconds. Then walk around, firing the flash at different sections of the room. For best results, don't allow the flash to appear in the scene, and never fire it directly at the camera--keep it pointed at the scene you want to illuminate. With a little experimentation, you can get some great results, like the photo here.

Good flash photos require a little human intervention. Most flash photos include a huge range of light levels--the flash has a meaningful effect only on the foreground, while everything else is exposed by whatever light happens to be available. (You can turn the flash off and get great photos in low light, especially if you have a tripod, as I did in this photo.) So how do you deal with that? You can use three settings to control any flash photo: ISO, aperture, and shutter. For more information, read "Use ISO to Take Low-Light Photos," "Making the Most of Aperture Mode," and "Making the Most of Shutter-Priority Mode."

If you don't like your flash photos, try changing the ISO. Another idea: If your camera has a flash power or flash compensation control, you can use those settings to fine-tune the shot. It's the background that generally needs your help. Try setting your camera to Shutter Priority mode: The slower the shutter speed, the more light you'll soak up in the background. Even if you pick a really slow shutter speed--such as an entire second--the foreground will remain sharp because its exposure is based the burst of light from the flash. I shot the photo on the left with a shutter speed of 1/60 second, and then reset the shutter speed to 0.5 seconds and took the photo on the right.

Ordinarily, your camera is programmed to fire the flash and then leave the shutter open for about 1/60 second. Sometimes, though, using the default results in an oasis of light in the foreground, set against a completely dark background, as if your subject were standing at the very entrance of Hades. A longer shutter speed can really hit the spot. Consider a nighttime or low-light scene in which you're trying to illuminate both a person in the foreground and the more distant background. As you know, the flash has a limited range, so it won't light the background. Here's an example of a typical shot in the early evening with the flash firing in automatic mode.

You can extend the principle I mentioned earlier--to use a slower shutter speed--to fix flash-induced exposure problems and create some exciting night photos. If you use a flash with your camera in manual exposure mode, you can get great portraits with vibrant colors in the background, especially shortly after sunset. For best results, dial in a shutter speed between 1/30 second and a full second. The slower the shutter speed, the brighter the background will be. In this case, you probably don't need to worry about using a tripod; the flash will freeze the action. The background might blur, but the effect can be appealing. Here's the same scene with a 1-second exposure.