We’ve discussed numerous methods of reducing camera shake, including the Reciprocal Rule, proper handholding technique, and other tips and tricks. Today, we’ll discuss a technological means for helping you minimize camera shake – image stabilization.
There are two main types of image stabilization: optical and digital. Both aim to do the same thing; reduce the effect of camera shake in your images. I’ve highlighted the word “effect” because none of these methods do anything to reduce the actual movement of the camera. Like handholding technique or using a fast shutter speed, they only take steps to reduce the impact of the moving camera on your images.
I’ll discuss digital image stabilization first, mainly because most photographers consider it inferior, and you should probably forget about considering it as an option as soon as possible. While there are digital image stabilization techniques used in video recording that are effective, for still photography, the implementation used most often by manufacturers is quite different, and poorly done.
What most digital image stabilization techniques do is to simply boost the ISO until you get a shutter speed sufficient enough to counter the camera shake. In many cases, this calculation uses the Reciprocal Rule to figure out what shutter speed is needed. As you can imagine from our discussion about ISO, this will typically result in images with a significant amount of digital noise and, therefore, a significant loss of image detail. In the end, you’ll probably end up with sharp, noisy photos, which isn’t a great improvement over blurry, noiseless photos.
Optical image stabilization goes by many, many names, but most methods work the same. Nikon calls their image stabilization VR for “Vibration Reduction”. Canon’s implementation is called IS for “Image Stabilization”. Sigma chose OS (Optical Stabilization), while Tamron uses VC (Vibration Compensation). Panasonic and Leica use MegaOIS (Optical Image Stabilization). Sony uses SSS (Super Steady Shot). Based on the names, you can see they’re all aiming at the same target.
Despite the acronym overload, most of those different systems are similar implementations of the same technique. In the above cases, the lens itself is the component that does the image stabilization, and it does this by using sensors in the lens that shift an internal lens element using magnets to counter the small movements of the camera. The image itself is stabilized before it hits the sensor or film, so no adjustment in exposure is needed.
Different IS systems tout different improvements, usually referring to an improvement in camera shake reduction by a number of stops. For example, 70-200mm VR II touts a 4-stop improvement by using VR compared with non-VR shooting. What this means is that you can effectively shoot sharp images, using the Reciprocal Rule as a baseline, with a shutter speed 4 stops slower than normal.
Example: At 200mm, the Reciprocal Rule states that you should shoot at 1/200 or faster to eliminate the effect of camera shake. With VR enabled, you could get sharp photos using a shutter speed as slow as 1/12.
(1/200 –1 stop> 1/100 –2 stops> 1/50 –3 stops> 1/25 –4 stops> ~1/12.5)
Getting sharp photos with a 200mm lens @ 1/12 is no small feat. And while 4 stops represents the best-case scenario, in real-world usage, it’s not uncommon to see an improvement of at least 2 stops, and sometimes more. Although not all image stabilized lenses can cite such a significant improvement, those with more modest figures in the 2-3 stop range are very effective in those figures.
Of course, these numbers all go back to good handheld technique. Without a solid handheld foundation, you’ll have great difficulty getting close to the shutter speeds I’m using in the above examples, and your lens’ IS system will have to work overtime in order to keep up, reducing it’s effectiveness.
While IS/VR/OS/etc. are wonderful tools, they’re not one-size-fits-all solutions. When shooting with a tripod, the motion sensors are actively looking for motion, and may actually activate the IS element when it’s not needed, reducing sharpness in your image. For this reason, IS is meant solely as an aid for handheld shooting, and it’s recommended to turn off IS when shooting with a tripod.
Adding in the IS mechanism also adds significant cost to a lens, sometimes resulting in prices significantly higher than their non-IS counterparts. For example, Canon offers several models of professional 70-200mm f/2.8 lenses. While the 70-200mm f/2.8L costs roughly $1350, it’s IS-equipped counterpart, the 70-200mm f/2.8L IS II runs roughly $2300. This varies from lens-to-lens and camera maker to camera maker. While IS was originally a feature only included on flagship-class professional lenses, it can now be found on many lenses included in entry-level packages. Nikon’s non-VR 18-55mm kit lens costs roughly $145, only a few cents more than the 18-55mm VR.
Lens-based image stabilization is one means of achieving optical image stabilization. Some camera manufacturers have incorporated a method of shifting the sensor itself, instead of the lens, to counteract camera movement. Notably, sensor-based IS has been used in some cameras by Sony (called SteadyShot), Olympus, Pentax, Fuji, and Samsung, among others.
Because the sensor itself moves slightly, lenses designed for a sensor-based IS system need to project a larger image circle, which can increase the lens’ size, weight, and cost. Also, because the sensor has to move, there’s a fixed range of it’s effectiveness, based on how much movement can occur. This makes sensor-based IS systems less effective with long telephoto lenses, where IS would provide the greatest benefit. However, because the IS system is built into the camera body, lenses do not require any IS elements and, effectively, any lens used will gain the benefit of IS.
If you find you’ll be doing a lot of handheld shooting, especially with telephoto lenses, IS can be a huge benefit, and may well be worth the extra cost. In many cases, especially in lower light, IS can be the difference between getting the shot and missing it. Gaining an optical advantage of 2 stops without having to boost ISO, and noise, is a significant benefit.