What's the difference between lens-based and sensor-shift image
stabilization? Our tests reveal all.
It's a fact of life: Everyone's hands move when taking pictures. No problem, if you have enough light for a fast shutter speed, your focal length is wide, or you're using a tripod. But for all those times when the light is dim, you're shooting with a telephoto lens, or you can't use a tripod, hallelujah for optical image stabilization.
DSLR shooters have a choice of two different technologies -- lens-based and sensor-shift -- to counter the photographer's motion. Some systems can even differentiate between ordinary shake and deliberate, lateral panning to capture a moving subject. (Forget electronic image stabilization, found on some compact digital cameras; it often adds image noise or reduces resolution, and it's good mainly for shooting video.)
While each type of optical stabilization has unique advantages, both claim to add 2 to 4 stops to your ability to shoot handheld without your motion blurring the image. So if you would normally set a 200mm lens to 1/200 sec in bright light, the most effective image stabilization will let you set your camera to 1/25 sec (3 stops slower) or even 1/13 sec (4 stops slower) in low light to capture a decent exposure with the same sharpness. Or you could use a smaller aperture in moderate or bright light to increase depth of field -- a boon to nature and macro shooters.
The big question: Which works better, lens- or sensor-based? Much is at stake, for photographers as well as manufacturers.
Canon, Nikon, and Sigma are dedicated to lens-based stabilization. All three have recently released new image-stabilized lenses -- also called vibration-reduction (VR) or optical-stabilized (OS). Tamron's version is expected soon.
Proponents of lens-based IS claim that designing the IS system to fit the characteristics of each lens means better performance. IS lenses also let you see the effects of stabilization through the viewfinder, which helps some shooters hold the camera steadier. But stabilized lenses tend to be significantly more expensive than their nonstabilized counterparts; they're slightly bulkier and heavier, too.