Nice and Steady
Unless you're one of those street performers capable of standing motionless for hours at a time, you may find it difficult to shoot with a handheld digital camera without inducing camera shake. Even slight hand movements can result in blurred pictures that look like the camera, or you, failed to focus properly. Blur is most likely to occur when lower light levels cause the camera to use longer exposure time, or when the subject or the camera itself is moving. The effects of camera shake also are amplified greatly in close-up photography as well as in pulling in distant detail with telephoto shots above 6x optical zoom.
Of course, you always can use a tripod. But what's the point of buying a compact camera if you have to lug around a tripod? Besides, if you don't have time to set up in advance, getting those spur-of-the-moment shots with a tripod could require Cirque du Soleil-type acrobatics.
Spurred largely by the need to offer competitive product, all of the big digital camera brands have stepped up development work on methods to compensate for camera shake. Each approach has at least a plausible story to tell, and they each have trade-offs. Let's look at these systems one at a time:
Optical image stabilization cameras use a dedicated lens group that moves to direct the image light straight to the center of the CCD, compensating for jitter. Panasonic's MEGA O.I.S, now featured on its entire Lumix range, employs a corrective lens driven by a linear motor to provide optical correction for hand movement detected by a gyro sensor (the sampling frequency is said to be 4,000 times per second). Moving lens type stabilization systems also can be found on snapshot-sized cameras from Canon, Nikon and Sony.
Moving up in class, Canon "IS", Nikon "VR" and Sigma "OS" SLR lenses have optical image stabilization built directly into the lens. Canon's new EF 70-200mm f/4L zoom, for example, employs several gyro sensors throughout the lens to detect camera shake vibrations and relay this information to a correcting lens group. The light path then is altered to position the image accurately on the sensor. Similarly, Nikon's second-generation VR2 system steadies the shot enough for handheld pictures at shutter speeds as much as four stops slower than otherwise would be possible without the degrading blur associated with camera shake.
Trade-off: Movable optical elements increase the cost and therefore the price of the camera or lens, and battery life is decreased due to power consumed by the motion actuators and sensors.
Manipulating exposure time and shutter speed. Hewlett-Packard's Steady Photo, as executed in the company's Photosmart R967, fights camera shake by increasing camera sensitivity (ISO number) and decreasing exposure time for a given scene. For instance, in full auto mode the camera may calculate an exposure of 1/15 of a second at ISO 200, but in anti-shake mode the camera will capture the exposure at 1/60 of a second and ISO 800. This works because doubling the ISO and halving the shutter speed result in the same exposure. Fujifilm's Finepix cameras also can adjust the ISO setting to give a shutter speed fast enough to eliminate blur due to camera shake.
Trade-off: When the effective ISO of a digital camera is increased, the noise in the image increases as well. Image noise manifests itself in small variations in color and is especially visible in single uniform color backgrounds such as blue skies and in shadows.
Imager shifting anti-shake. Used by Sony in its DSLR-A100, this approach has sensors in the camera body to detect the direction of the movement and micromotors to shift the CCD imager assembly up, down or sideways to counteract image-blurring camera movement. Samsung's Optical Picture Stabilization (OPS, found on its GX-10 digital SLR) and Pentax's Shake Reduction, seen on its new K100D digital SLR, also prevent blurred pictures by shifting the CCD to counter any movement of the camera's body.
Trade-off: Image-shifting stabilization steadies the recorded picture, but you can't see the effect in the viewfinder, so it may be hard to know if it is working. Also, applying anti-shake at the image sensor does not always work as well with long, heavy lenses.
It appears engineers are getting the upper hand on camera shake problems at just the right time. According to CEA's 13th Annual CE Holiday Purchase Patterns published in October 2006, digital cameras topped the gift list of what consumers planned to buy this past holiday season. Overall, CEA expects 27.5 million digital cameras will be sold by dealers during 2007, up from 26.7 million last year.
By Murray Slovick
