Maximising the Potential of Image Stabilisation

Image stabilisation (aka ‘anti-shake’ or ‘anti-blur’) has become a key feature in many digital cameras, both digicams and DSLR models. It’s easy to see why it’s so popular with photographers; camera shake is a major cause of blurred shots. Three systems are currently popular.

The first simply increases the sensor’s sensitivity, allowing the photographer to shoot at a faster shutter speed, thereby reducing the chance that camera or subject motion will produce blurring. This system is popularly referred to as ‘ISO boosting’ or ‘digital image stabilisation’.

The second combines sensors that detect camera motion with a compensatory mechanism that shifts the image sensor to counteract it. Cameras with ‘CCD-shift’ stabilisation use this system. Pentax uses the term ‘Shake Reduction’ and Sony uses ‘Super Steady Shot’ to identify this type of IS in their DSLR cameras.

The third, which is also found in some interchangeable lenses for DSLR cameras, uses similar motion detectors to the CCD-shift system but mounts them in the camera’s lens and compensates for camera movement by shifting an element (or group of elements) in the lens. It’s variously known as ‘optical’ or ‘lens-shift’ image stabilisation in cameras and ‘image stabilisation’ or ‘vibration reduction’ in lenses.

Which Works Best?
The first method is the cheapest to implement – but also the least effective for counteracting camera shake – although it is usually better for dealing with subject movement than the other two methods. Unfortunately it has potential to degrade picture quality. Increasing the ISO may allow you to shoot at faster shutter speeds but high ISO settings are inevitably associated with an increase in image noise. This may not be obvious if you keep prints below A4 size.

CCD-shift stabilisation is very effective at counteracting camera shake and gives a 2 to 3.5-stop advantage over unstabilised cameras, according to manufacturers’ claims. The main benefit of this system is that it works with any lens that can be fitted to the camera, so you don’t need to pay extra for image stabilised lenses.

Lens-shift stabilisation is the most effective of the three options – and it’s particularly effective in interchangeable telephoto and long-zoom lenses. Manufacturers typically claim they allow photographers to use shutter speeds 3-4 stops faster than unstabilised lenses. Microprocessors in the lens continuously analyse camera movement so they can identify whether it’s intentional and, therefore, not requiring correction. Camera movement associated with recomposing shots or tracking subject motion is ignored.

Most systems have separately-controlled pitch and yaw detectors, which pick up horizontal and vertical movement. To allow for panning, many cameras and lenses provide two IS modes. Photographers can switch off the horizontal detector for panning shots or use both detectors for general stabilisation.

Some cameras combine CCD-shift or lens-shift IS with ISO boosting strategies to give photographers even greater exposure flexibility. Use ISO boosting judiciously if you plan to enlarge pictures beyond A4 size.

When IS is an Advantage
Whether or not IS is worthwhile depends on the types of pictures you take. Anyone shooting with a zoom lens that has more than 5x magnification will probably benefit from IS – and the higher the zoom ratio, the more useful it will be. Sports and wildlife photographers find IS lenses indispensable because they enable them to shoot at lower ISO settings, thereby minimising the risk of image noise.

IS is also advantageous in dim lighting, both for indoor shots without flash and for outdoor shots after sundown. It is particularly handy for portrait shots where both camera and subject movement can affect shots.

Work-Arounds for Image Stabilisation
Suppose you need some kind of stabilisation and your camera or lens doesn’t have it? There are a couple of work-arounds that can help you to minimize blur in shots:

1. Use a tripod or monopod. If you can steady the camera in at least one dimension you will reduce the change of associated camera shake in that dimension.
2. Use burst mode (continuous) and brace yourself against a stationary object. Squeeze the shutter button slowly and gently, firing off a burst of at least three shots. One image in the set will probably be sharper than the rest. (This strategy forms the basis of Nikon’s BSS mode.) Note: you can identify shots that are likely to be sharp by looking for the largest JPEG files in the set.