If you're confused by the "IS" that might be tacked on to the end of the name of the digital camera you're considering, you aren't alone. IS, when used with a digital camera, is short for "image stabilization technology," which allows the camera to help you reduce blurry photos from camera shake.
Although camera image stabilization isn't new, more consumer-level digital cameras now include IS technology. As IS becomes more prevalent, it's important to know what you're buying, as image stabilization is available in a few different configurations.
The three primary configurations of digital camera image stabilization are:
- Optical IS
- Digital IS
- Dual IS
Image stabilization technology uses either hardware or software inside the digital camera to minimize the effects of camera shake or vibration. Camera blur is more pronounced when using a long zoom lens or when shooting in low-light conditions, where the camera's shutter speed must be slower to allow more light to reach the camera's image sensor. With a slower shutter speed, any vibration or shake occurring with the camera is magnified, sometimes causing blurry photos. Even the slightest movement of your hand or arm could cause a slight blur.
IS cannot prevent every blurry photo—such as when a subject is moving too fast for the shutter speed that you're using—but it works well with correcting blur caused by the slight movement of the photographer (don't feel bad; every photographer has this problem occasionally). Manufacturers estimate IS can allow you to shoot a couple of shutter speed settings slower than you could without IS.
For compact digital cameras aimed at beginner and intermediate photographers, optical image stabilization (sometimes shortened to OIS) is the preferred IS technology.
Optical IS uses hardware corrections to negate camera shake. Each manufacturer has a specific configuration for implementing optical IS, but most digital cameras that contain optical image stabilization use a gyro-sensor built into the camera that measures any movement from the photographer. The gyro-sensor sends its measurements through a stabilization microchip to the CCD, which shifts slightly to compensate. The CCD, or charge-coupled device, records the image.
The hardware correction found with optical IS is the most precise form of image stabilization. It does not require increasing the ISO sensitivity, which can compromise photo quality.
Digital image stabilization only involves using software and digital camera settings to minimize the effects of camera shake. Essentially, digital IS increases the ISO sensitivity, which is the measurement of the camera's sensitivity to light. With the camera able to create an image from less light, the camera can shoot at a faster shutter speed, which minimizes blur from camera shake.
However, digital IS often overrides the ISO sensitivity beyond what the automatic setting on the camera says it should be for the lighting conditions of a particular shot. Increasing the ISO sensitivity in that manner can degrade the image quality, causing more noise in the image—noise is any number of stray pixels that don't record properly. In other words, asking the camera to try to create an image at less-than-optimal ISO settings could compromise image quality, and that's what digital IS does.
Some cameras also refer to digital image stabilization to describe a piece of software built into the digital camera that tries to minimize the blur after you take the photo, similar to what you could do with image-editing software on your computer. This type of digital IS is the least effective among all types of image stabilization, however.
Dual IS isn't quite as easy to pin down, as manufacturers define it differently. The most common definition of dual image stabilization involves a combination of hardware stabilization (as found with optical IS) and increased ISO sensitivity (as found with digital IS).
Sometimes, dual image stabilization is used to describe the fact that a digital SLR (single lens reflex) camera contains image stabilization technology in both the camera body and in its interchangeable lenses.
Working Without IS
Some older digital cameras don't offer any type of IS. To prevent camera shake in a digital camera that doesn't offer image stabilization, try these tips:
- Mount your camera on a tripod.
- Use the camera's viewfinder, rather than the LCD, to frame the shot.
- Steady yourself as you shoot by leaning against a wall or door frame.
- Brace your elbows against the side of your body and hold the camera with two hands.
- Shoot at a fast shutter speed all of the time, which isn't always a practical option.
Don't Be Fooled
Finally, be sure you understand exactly what you're buying when it comes to image stabilization in your digital camera. Some manufacturers, especially those with low-priced models, will use misleading terms, such as anti-blur mode or anti-shake technology, to try to hide the fact that their digital camera doesn't offer IS. Such cameras usually just increase the shutter speed to limit blurry photos, which sometimes causes other exposure problems, thus harming image quality.
As an added note, some digital camera manufacturers have specific brand names for optical image stabilization, further complicating things for the shopper (as if we need more confusion). For example, Nikon sometimes uses "Vibration Reduction," and Sony sometimes uses "Super Steady Shot" to refer to optical IS. Before buying a particular model, make sure that its brand name refers to optical IS and not some form of digital IS. You should be able to find this information on the manufacturer's web site or from a trusted salesperson at your camera store.