More and more camera and lens manufacturers are turning their attention to image stabilization – many claiming up to 4 stops. So what does all this mean?

I have to admit, regardless of how much I read on the subject I really didn’t fully understand image stabilization until I got a lens with this technology built it to it. It was only then that I started to appreciate what it could and could not do.

Because various manufactures use terms that are unique, such as – Image Stabilizer (Canon), Optical Stabilizer (Sigma), Vibration Reduction (Nikon) – I’ll use “Image Stabilizer” as a generic term.

There are two types of Image Stabilization

The first type of image stabilizer is ‘optical stabilization’ which is built into the lens and consists of a ‘lens set’ inside the lens barrel that actually moves from side to side and up and down. Without getting too technical, motion of the lens is detected be gyroscopic sensors and this the lens set is moved accordingly to counteract the motion of the lens itself. Ideally this results in a non-moving image striking the image sensor inside the camera. From my experience this works extremely well

The second method of image stabilizer is ‘sensor stabilization’ which works on a similar principle to optical stabilization by detecting movement of the camera (not the lens) but instead of moving a lens set, the compensation is applied directly to the image sensor itself inside the camera, thus achieving the same result as with the optical stabilizer method.

There are arguments for both methods. One such argument is, since this technology is expensive, it is better to buy it once – inside the camera controlling the sensor movement. The contrary argument is – all lenses are different and therefore need matching stabilization technology, but this means buying the same expensive technology in every lens.

Another argument is – with ‘optical stabilization’, what you see is what you get, meaning that when you are looking through a SLR viewfinder, the image is stabilized. That is, it’s seen to be steady, whereas with the ‘sensor stabilizer’ the stabilization cannot be witnesses in the viewfinder. It is only after the image has been captured that the results can be appreciated.

A third possible argument is, since the image is ultimately going to strike the sensor, it’s better to stabilize the sensor rather than the lens.

The magic of Image stabilization

Most manufacturers now claim their stabilization technology can compensate for as much as 4-stops in some cases. While there is a moment of truth in these marketing claims, remember, they are marketing statements and not entirely accurate.

The old rule of thumb was – the shutter speed should exceed the focal length of the lens. For example, a 125mm lens requires a shutter speed of 1/125 or faster. It is assumed that this shutter speed will be sufficient to minimize any movement made by the camera during exposure. Now let’s add Image Stabilizer technology into that equation. The manufacturers claim four stops. That means – 1/64 = 1 stop – 1/32 = 2 stops – 1/16 = 3 stops and 1/8 = 4 stops. The manufactures are right. I can look through a lens with 1/8 of a second and the image is remarkably stable. But the shutter speed has nothing to do with image stabilization. You see – I fooled you when I said that at 1/8 of a second the image is remarkably stable. The fact is – I’m looking through an open lens. It doesn’t matter what speed I have the camera set at. Now take a look at this picture.

The interesting thing about this picture is it was taken at a focal length of 120mm and at a speed of 1/8 of a second (f5 and ISO1600). Now I have no doubts that the Image Stabilizer was working at the time and doing a fine job of holding the image still, but is this the expected result? Why is there movement? I’m exactly 4 stops less that the 1/120 of a second that is considered a standard.  The answer is, the saxophone player was moving and he moved a long way in 1/8 of a second, far more than if he would have moving in 1/120 of a second. So while image stabilizers do a magnificent job, the results can sometimes, let’s say, different’ than expected.  So the thing to remember is – Image stabilization can only reduce camera/lens movement – they cannot stop image action.

One last comment

One of the weird side effects of using Image Stabilization is the effect it can have on the senses. Our bodies have senses that help us navigate through life, in particular, we tend to rely heavily on our sight in conjunction with other senses to maintain our balance. I found that when looking though the viewfinder, my sense of balance is somewhat disturbed. Those slight visual movements that are conveyed to my brain so that it can send signals to my muscles to compensate my stance are been ‘neutralized’ by the Image Stabilizer and I’ve frequently found myself off balance – a rather weird sensation.