Rangefinder Magazine
October 2001/Columns

First Exposure by Bob Shell
Canon’s Image Stabilization (IS) Technology

Ever since cameras got small enough to hold by hand photographers have sought ways to keep them steady enough for handheld shooting. Certainly the best way to get razor-sharp images is to support the camera on an absolutely steady support, the larger and heavier the better. A well known photographer once quipped to me that the best tripod was a five ton granite block with a tripod screw on the top, and that is not much of an exaggeration. But locking the camera down onto such a solid support is not always a practical option.

Working hand-held with even a short telephoto risks blur from lens/camera motion. This is true even in bright light at relatively high shutter speeds, as in this beach shot from St. Thomas. I wanted to allow Anna maximum freedom of movement and this ruled out any sort of camera support. Taken with the Canon 28–135mm EF IS lens at the 135mm setting on a Canon EOS-3. (Model: Anna Chemavonian.)

Vibration and camera movement are the worst enemies of image sharpness, and the quest to tame them while retaining maximum camera mobility has been a long and hard one. One of the first ideas was to use the stabilizing effects of a gyroscope. Systems were developed which used relatively large and heavy twin gyro systems attached to the camera or lens. Initially these systems were not developed for photographic purposes at all but for stabilizing high-powered binoculars for use aboard ships almost 50 years ago. These systems worked reasonably well, but the resistance of the gyros to rapid movement often frustrated photographers by making it difficult to quickly make large changes in camera direction. These external gyros also required battery power from rather bulky, heavy battery packs. But they were the only device which worked, and so photographers put up with them. Many are still in use today in cinematography and other applications for which they are well suited. I have also heard of photographers in particularly difficult situations combining the external gyroscopic stabilizer with Canon’s IS system, so the use of external gyros is far from dead. For more information on the Ken-Lab gyro stabilizers check out their web site at www.ken-lab.com .

Some optical engineers realized that it was not really essential to stabilize the entire camera and lens, and that stabilizing a sort of wedge-shaped optical element inside the lens could accomplish the same effect with much less mass and less resistance to changes in the camera direction. The first system I am aware of which used this idea in a commercial product was the Schwem Gyrozoom, built by Schwem Technology in California in the 80s. The Gyrozoom was designed for commercial motion picture and video camera use. Unfortunately, the company has been out of business for almost 10 years, according to my sources, and lenses are available today only for rental. I was astonished when first shown samples of video shot with the Gyrozoom from helicopters in rough winds. The images were absolutely sharp and steady. But the Gyrozoom still used a relatively large gyro system, which required an external power source, and was never made in a version for still photography.

Here is where IS can really save the day. I was working handheld in a gondola in Venice and relied on the lens to give me sharp images in the shade between the buildings on 100 speed chrome film. Taken with the Canon EOS-1V and 28–135mm EF IS zoom on Agfa RSX 100 II film.

Also in the 80s, I was briefly involved as a consultant on a project to produce image stabilized binoculars and SLR lenses using a passive system in which a lead weight would replace the gyro system and require no power. This passive system was demonstrated to work well in prototypes, but the project was killed for reasons having nothing to do with its viability, and we had to wait some years before other optical firms again took up the challenge of making an image stable when the camera and lens were in motion.

First shown in a prototype in 1993, the Canon IS system was similar and different at the same time. Like the Gyrozoom, it used a moving optical component inside the lens, but unlike the Gyrozoom, this element is not mechanically linked to a large gyro. Canon instead chose to use tiny gyros to detect the lens movement and a servo system to actually move the optical component. Linking the sensors to the servos are some highly sophisticated proprietary electronics. Hopefully, the drawings here will make clear just what happens inside one of Canon’s IS lenses when lens motion is detected.

Nikon was also working on developing image-stabilizing systems for 35mm and digital SLR cameras and has introduced their own system called VR, which is similar in general to Canon’s but has enough differences in approach to show its separate pedigree. The main difference that I am aware of is that Nikon’s system allows you to set the system to apply stabilization to the image on the film but not the viewfinder image. This not only saves battery power but eliminates the viewfinder effect of stabilization which some people apparently find disorienting.

Zeiss has also developed image-stabilizing systems, but so far has confined their application to binoculars. I would not be surprised to see image stabilized lenses from this venerable optical house in the future, as well as from other makers who have told me confidentially that they are developing similar systems.

Does it Work?
Enough of history and theory, photographers just want to know one thing, does it work? The answer, as usual, is a qualified one. It depends on just what you want to photograph and how. Although I have not had the opportunity to work with the Nikon VR system yet, I have handled the lens and spoken with photographers who have used it, so my comments should be accurate. I have had extensive experience shooting with several of the Canon IS lenses. I have come to rely on the IS system as an extra guarantee of image sharpness when use of a camera support is impossible, impractical or just inconvenient.

Every photographer who works with active subjects which can not be approached closely need to use long lenses. In most cases, a 300mm is just about the shortest lens a sports or wildlife photographer will carry, and the longer the lens the more of a problem vibration is. Telephoto lenses magnify camera and lens motion just as they magnify the image, and the old photographer’s rule of thumb was never to use a shutter speed shorter than the reciprocal of the focal length of the lens if you wanted sharp images handheld. In the real world this is not always practical, since you may want to shoot that 300mm lens at 1ž30 second to get the effect you want or to work with lighting limitations. Sure, you can shoot anything and everything from the security of a big heavy tripod, but you will miss many fine photos in the process. This is what makes image stabilization such a useful feature.

For my first tests of image stabilization I borrowed a Canon 300mm f/2.8 with IS and did a series of shots outdoors using the lens without a tripod. For one sequence I used IS and for another I switched it off. In the sequence with IS turned off, I could detect camera shake easily on the lightbox starting at 1ž125 second, which is what I would have expected, and by the time I got down to 1ž60 and slower, the images were turning into nice pastel blurs, some of them quite attractive but certainly not what I wanted. In the sequence with IS active, the sharp images extended down to 1ž60 second and kept going! Even shots at 1ž15 second were sharp through a 10X loupe and the blur only started to become a problem at 1ž8 second and longer. Now, admittedly, I was taking every possible precaution in this series to make myself as stable as possible before tripping the shutter. I stood with legs apart, elbows pulled in and under, and exhaled and held my breath prior to each shot. Later I experimented with sloppy technique and grab shots with no preparation and found that I was getting sharp images down to 1ž30 second.

Since that series of tests I have been sold on IS, plain and simple. I’ve come to consider the 28–135mm IS zoom as my “normal” lens for most of my work, and have also been doing a lot of work with the 100–400mm IS zoom, which is a genuinely amazing lens. Would I buy a long lens today without image stabilization? Most likely not. It just expands my working horizons too much, and I would feel crippled without it.

So far I’ve talked about the obvious uses of image stabilization in outdoor work by available light. But there is another whole area in which IS can shine, and that’s in the studio. Recently a number of photographers I know have been experimenting with tungsten-halogen “hot lights” in the studio, and I have been as well. When working with black and white, color negative, tungsten-balance chrome films, or with digital sensors, excellent results can be obtained from these lights.

Even though some flash systems have modeling lamps which mimic the look of the actual flash pretty well, there is still always a difference between what your eye sees and what is recorded on the film or digital sensor. With hot lights this is not an issue. To borrow a computer term, they’re WYSIWYG (What You See Is What You Get). But when working with people, you can’t have the lights too hot or you will wilt your subject, as with flowers, food, and many other subjects. With the brightness and heat set for comfort you will often find yourself shooting at slow shutter speeds. This is no problem when working with a still life subject and the camera on a tripod, but when working with a model in the studio I like to handhold the camera so I can move around quickly for different camera angles. Image stabilization has come to my rescue, allowing me to stop the lens down for the depth of field I want and still get sharp images at moderately slow shutter speeds of 1ž30 and even 1ž15 second.

I think it best at this point to just stop writing and let the pictures and their captions tell the story. As the old Chinese proverb, usually quoted incorrectly, says, “One picture is worth 10,000 words.”

Here is a list of Canon lenses featuring IS technology:
EF 300mm f/2.8L IS USM
EF 300mm f/4L IS USM
EF 400mm f/2.8L IS USM
EF 500mm f/4L IS USM
EF 600mm f/4L IS USM
EF 28-135mm f/3.5–5.6 IS USM
EF 75-300mm f/4–5.6 IS USM
EF 70-210mm f/2.8 USM
EF 100-400mm f/4.5–5.6L IS USM
EF 400mm f/4 DO IS (announced but not available yet).

Bob Shell is well-known worldwide as a photographer and writer on photography. He is the author of more than a dozen books on photography and thousands of magazine articles. He is the “Photo Guru” for BestStuff.com and is recently retired as editor of Shutterbug after more than 20 years on staff.