March 13, 2011, 8:22 a.m.
posted by redphone
Freeze Action with Electronic Flash
The hand is quicker than the eye, and your electronic flash is faster than your shutter. Use it to stop time and capture that magic moment.
The shutter on your camera can reach speeds of 1/2000 of a second or faster. The faster the shutter speed, the easier it is to stop action—that is, freeze your subject in its tracks or, in the case of Figure, in mid flight. The challenge with a fast shutter speed is that it also severely reduces the amount of light passing to the image sensor. So, you have to either open up the aperture all the way (f-2.8 or so), increase your ISO speed (to ISO 400 or more), or both. And even then, you still might not have enough light to capture the picture.
A hummingbird captured in flight with flash
But there's a workaround for these limits imposed by the laws of physics. Your camera's electronic flash is an excellent tool to stop action when you don't have enough light to use a super-fast shutter speed.
In fact, even when you do have enough light, you still might want to use the flash. Why? Your camera's shutter probably tops out at 1/2000 of a second or so. But the electronic flash is just getting warmed up at that speed, and some external units can emit bursts of light as short in duration as 1/50,000 of a second. Now that's high-octane performance!
And it gets even better. Since the flash adds light to the scene, you don't have to fiddle as much with aperture and ISO settings. It's rare when you get to have it all in photography, but this is one of the few occasions where that's possible.
To use this technique, you first have to make sure the flash fires. If you're outdoors, switch to Fill Flash or Flash On mode. Now, make sure you're within range of your flash. For most built-in units, this means eight feet or closer. You can extend this range if your camera accepts an external flash, which is more powerful.
If you're using a point-and-shoot digicam, you're still going to have to deal with shutter lag: the delay from the moment you press the shutter to when it actually fires. You'll have to anticipate the decisive moment and shoot accordingly. Digital SLR shooters have more responsive cameras and don't have to compensate nearly as much for lag. Get to know your camera, and go from there.