One specification that is becoming increasingly common among digital cameras, is the provision of some means of reducing or offsetting the camera shake situation that can often occur in circumstances where low light levels are encountered, or long focal length lenses are used, and the camera and lens are being hand held. It is particularly common when they are combined. When camera shake happens, the shutter speed used not being high enough to counter any camera movement, the result is a blurred and out of focus image. Whilst these can be viewed as artistic under certain circumstances, and if done intentionally can sometimes be quite good, for most they are at the very least disappointing, and in some cases disastrous.

One way to offset shake is to use a tripod, another flash illumination, but this isn't always possible for any number of reasons. So camera makers are offering a number of different ways of counteracting it. An easy one which requires little effort or cost is simply to increase the ISO rating to raise the shutter speed, and so the Auto ISO option has arrived, but this has it's downside in the reduced image quality that almost invariably results with the use of higher ISO's. Of course this option is available to anyone with a digital camera whether the auto-ISO option exists or not, as any cameras ISO can be changed at any time.

The other options are more expensive to produce. These involve optical solutions, anti-shake sensors, where the sensor moves in relation to the lens image, or lens image stabilization, where special lens elements move to keep the lens image still on the sensor. We'll take a look at both systems because they each have both advantages and drawbacks. And which one you prefer will dictate you choice of camera. Or which camera or DSLR system you already use will do likewise, dictate the system that is available to you to use.

Lens Stabilization

Countering camera shake by moving lens elements has been in existence for some years, and first arose in video camcorders. Canon used it in their video cameras and subsequently it started to appear in certain of their expensive and long focal length telephoto SLR lenses as a method of assisting in the capture of sharp and blur free shots taken with these lenses. Proving to be a considerable advantage the range of lenses using this feature, which Canon call IS (Image Stabilization), has risen considerably in recent years, especially since the move to digital capture, and now encompasses lenses of all focal lengths and focal ranges.

As the feature is tailored to each individual lens and the focal lengths it has, it can be optimized to produce the greatest benefit possible over the whole of the lens's focal range and focus distance. The average gain is around 3-4 Ev stops over the shutter speed needed for any given focal length. This is a quite considerable advantage. It means for example that using a 500mm lens a shutter speed as low as 1/60sec is enough, when the minimum is usually 1/500sec, and using 1/30sec might prove possible

A lens with IS does not have it permanently engaged, and it can be turned on and off as needed. This is because as it works continuously when in use it consumes a considerable amount of power, and can have a significant impact on camera battery life, these being drained quite quickly. It can double camera power consumption, and generally halves the number of shots it is possible to take on a single battery charge compared to that normally obtained. Another downside to it is of course that new lenses using IS have to be purchased to take advantage of the system, but these can be used with many existing cameras. So new lenses are needed, but not necessarily a new camera.

Besides Canon there are other camera makers that have also adopted the use of lens stabilization in light of the benefits Canon proved it brings, and perhaps of these Nikon is the best known. They have given their stabilization the name VR (vibration reduction), and many Nikon lenses now feature it.

Perhaps one of the nicest benefits that the use of lens stabilization brings, besides that of lower shutter speeds and sharper shots, is that the effect can be seen working through the viewfinder, the image seen being still and stable.

Anti-Shake Sensors

An alternative method of offsetting camera shake first arose after the introduction of digital cameras into mainstream use and was developed by Minolta for use in one of their prosumer digicams. This was a method of moving the sensor to achieve the same basic result as moving lens elements, producing a sharp and blur free shot, and gained the generic title, anti-shake sensor. Proving successful in use the basic design concept was then used by Minolta in the DSLR's that they made. This was seen as a huge benefit, for it worked with any lens used on the camera. This meant that new lenses were not needed, just a new camera body.

However there are some downsides to it's use. Because the design is not tailored to a specific lens or focal length it's overall effectiveness is less than that achieved by lens stabilization, between 2-3 Ev stops over the normal shutter speed used. It is at it's most effective with longer focal lengths, which reduces as the focal length shortens. Another aspect is that it has a minimum focus distance of around 1.5m under which it appears not to work at all, or not to any extent. This is a considerable drawback for it means there is no advantage gained in using it at close quarters, say with a macro lens at large magnification.

As with lens stabilization it can be turned on and off as required, but in comparison it can't be seen working in the viewfinder, the image seen remaining blurred, as it doesn't work until the shutter is fired and the shot taken. To date there isn't a great deal of information as to the power consumption of anti-shake sensors, nor is it known as to whether the design works all the time behind the shutter, or only when it is open. So until we hear to the contrary we assume that power drain is similar to that of lens stabilization.

Besides Sony, who have taken over the former Minolta camera business, Pentax and Olympus have developed and introduced their own anti-shake sensor systems which exist in most DSLR's that they make. 

Further comments

On the face of it any method of eliminating or reducing camera/lens shake is to be welcomed. And there are several that can be used. Resting the camera on a fixed surface is one. Almost any surface can be used to rest a camera on, or against. Obviously a flat one is best if you want a landscape type shot. It also gives the opportunity to use as slow a shutter speed as needed, and the self timer if required. A lamp post or something similar is good for resting a camera against on the spur of the moment. Unlike a flat surface you can't leave it there on it's own, you've still got to hold the camera. But it's helpful for keeping the camera stiller than you can hold it on it's own. Using a bean bag, monopod or tripod are all are variations on the theme, with advantages and disadvantages between each other.

Using flash is an option that is useful under certain circumstances to freeze action or prevent image blur, but brings with it a range of problems of it's own. It alters the tone and illumination style of a shot and only works within certain parameters, mainly the power capabilities of the flash equipment used. It's difficult on the spur of the moment to judge what the image outcome will be, and is best used when some experience of using it in various scenarios has been acquired or test shots to establish the likely outcome can be taken. Test shots are often the only way of establishing whether any reflective surfaces exist and will be problematic.

As a general rule of thumb the minimum shutter speed to use has been determined as that nearest to the reciprocal of the focal length of the lens. It applies right up and down the scale. So for a wide angle lens, say a 28mm, 1/30th sec is needed, for a 50mm,1/60th, for a 200mm,1/250th and so on. This rule applies only to static subjects i.e. where no movement is observed. In shots that are taken where there is subject movement then high shutter speeds are needed regardless of the focal length of the lens used and are generally tailored to the speed of the subject across the image plane and it's distance from the camera. Panning is a technique often used to follow a subject moving at speed and freeze it's movement whilst the background remains blurred, giving detail of the subject but invoking a sense of it's speed at the same time. 

Using stabilization systems when panning can cause problems, and some require alternative settings when doing so, if the desired effect, a sharp subject with a blurred background, is to be achieved. Some can't be used at all.

With digicams it doesn't really matter which system is fitted into the camera, a moving sensor, or moving lens elements, since the whole camera/lens is a self contained unit. At first glance DSLR's that use sensor movement to gain anti-shake seem the best option. Buy one and any lens that will fit on the camera mount can be used and benefit. But the downside is the camera is often bigger and heavier to incorporate the moving sensor, and there are more complicated parts with the chance of going wrong. And if this does happen then you have no camera to use. And of course you have to buy an expensive new camera body to benefit in the first place. At the moment Sony (Konica-Minolta), Pentax and Olympus use anti-shake sensor systems in their latest cameras. And as the systems are already being refined and improved, it makes you wonder just a little bit how reliable they will be long term. Until the technology is mature, and has been proved in long term use, it's really anybody's guess.

DSLR systems that use just certain lenses fitted with anti-shake means those with current DSLR bodies need only buy the lens they need. And although it will also have more complicated electronic parts inside compared to an 'ordinary lens', should for any reason the lens fail, the rest of the camera system is unaffected. And by contrast with anti-shake sensors, as the optical stabilization of lenses has been around for quite some time the technology could be said to have been proved. Since it is really with the use of longer focal lengths that the biggest advantage is gained, as light levels are usually high enough for the correct shutter speeds for short focal length lenses, it is mainly longer focal length lenses that benefit from stabilization. When shutter speeds aren't high enough for short focal length lenses then frankly you need some firm support of some kind anyway.

However it is only with the Canon EOS system that anti-shake lenses can be used with any camera body. This is because Canon are the only maker to have used AF motors in the lens alone, requiring electrical power contacts between camera and lens, a basic design of the EOS mount system. This has a big advantage for users of the system since the lenses are usable with all past film bodies as well as the current digital one's. An unusual case of backwards compatibility on the part of Canon. By contrast Nikon's VR lenses can only be used with certain bodies where suitable connections exist, the newer one's mainly, which are equipped with contacts to accept and use the new SWM (Silent Wave Motor) lenses.

Cost is another factor to consider. DSLR's with anti-shake sensors often don't cost much more than DSLR's without, whereas anti-shake lenses are generally much more expensive than their non anti-shake versions. Users of Canon's EOS system are perhaps in the best position if they are happy with their current camera bodies or use a mix of film and digital, and many still do, as all they need is the IS lens of their choice. Pentax, Sony, and Olympus users have the most cost effective option, with the biggest gainers being those just starting to use their systems, since a new body is all that's needed to make all lenses anti-shake. Worse off are undoubtedly Nikon system users. Not only do they need the right body, which might mean a new one, they also have to buy the anti-shake lenses on top, a double whammy.

So It's a real case of swings and roundabouts for DSLR users, and the options you have are determined by the DSLR system you have chosen to use, or intend to choose in the future. At the end of the day however, whilst anti-shake is undoubtedly an advantage to have, one of the biggest choices of all is whether you feel you need it in the first place. For as we have said, it's an advantage, but certainly not a cure-all. And the experienced may well decide they don't. Or will wait until such times as the technology is mature and proven to be reliable.

After all most photographers have managed to do without it so far, one way or another.