Stop-Action That Saves the Picture

By Rob Pegoraro
Sunday, October 8, 2006

Digital cameras let people edit their shots within seconds of taking them, then share the photos with the folks back home before they've even returned from vacation. Now digital cameras are making a different sort of trick commonplace: the ability to stand still.

This feature, called "image stabilization" or "vibration reduction," offers a way out of an old photographic dilemma: If you have to hold the shutter open for too long, the shot will blur unless you park the camera on a tripod or some other fixed base.

"Too long" can mean just one-fifteenth of a second. Even one-thirtieth of a second can be enough time for the camera to shift in your hands and record a double or triple image of the subject.

Image stabilization allows the camera to realize that it's in motion, then damp out that movement to keep the image fixed. One type of image stabilization, called optical, uses sensors that detect any vibration, then move the lens or image sensor in the opposite direction to compensate.

In a less-powerful form of image stabilization, known as digital or electronic, the sensor's vibration data is processed and used to alter the just-recorded image to iron out bumps and wrinkles introduced by any movement.

When it works, it opens up new areas of photography. Shots in low-light conditions don't have to be limited to subjects within range of the flash or those that will permit you to set up a tripod beforehand. It can also increase the utility of telephoto shooting, in which the long zoom lens would otherwise magnify the effect of every minor shake of your hands.

This feature was once an expensive rarity confined to high-end models, some film and some digital. But over the past year, it has crept into more affordable digicams, such as the three I tried out: Canon's $400 A710 IS (7.1 megapixels, 6x optical zoom), Nikon's $350 Coolpix S7c (7.1 megapixels, 3x optical zoom) and Panasonic's $280 Lumix FX3 (six megapixels, 3x optical zoom).

The Canon and Panasonic employ optical image stabilization, and the Nikon uses digital. All of them delivered on the basic promise of this technology, salvaging shots that would otherwise have wound up getting trashed.

In a batch of side-by-side tests, the optical stabilization on the Canon and Panasonic and the digital stabilization on the Nikon seemed about equally capable of extracting a decent photo from a mediocre setup. All three cameras could smooth out most 1/30 {+t}{+h}- and 1/15 {+t}{+h}-second indoor exposures, as well as many outdoor shots taken while rapidly shaking the camera.

But the Canon and Panasonic could also extract decent shots from still slower exposures. And at any shutter speed, they could take the next shot right away, while the Nikon needed time to fix the image with its software. This lag, from two to eight seconds, was the longest shot-to-shot wait I've seen on a digital camera.

Digital stabilization's processing can also come with a more subtle trade-off: Details can get dropped or garbled as the camera's computer tries to fix the photo. (Nikon uses optical stabilization in other cameras; on the S7c, it says that digital stabilization allowed it to keep the camera just 3/4- inch thick.)

The extra work involved in running the stabilization circuitry did not seem to have any effect on battery life.

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