Image Stabilization
Compensating for Camera Shake
Use digital camera image stabilization to
reduce your minimum "safe" shutter speed.
If you watch camera technology developments, you can't help but notice the megapixel wars. These are the most obvious attempts by manufacturers in vying for consumer attention.
Today, that battle is less significant, since most cameras have more megapixels than we amateurs really need.
The new battlefront is technology that reduces the minimum amount of light required to take a sharp photograph. Megapixels are good at grabbing attention, but helping users to take sharp pictures with less light adds considerably more value.
Two technologies that contend in this arena are higher, noise-free ISO settings and digital image stabilization.
- Higher ISO settings make your camera more sensitive to low light levels.
- Image stabilization, the subject of this page, compensates for camera motion at low shutter speeds.
Why Have Stabilization?
It is impossible to handhold a camera perfectly steady. Even the slight motion of pressing the shutter will move your camera. With a fast enough shutter speed, though, the motion will not be evident in the image. If your shutter speed is too slow, you will create blur in your images.
Image stabilization helps to reduce the chance of blur by offsetting the motion of the camera and lens.
An Example Without Stabilization
The impact of camera motion is proportional to the focal length of your lens. Longer lenses cover a narrower angle of view. For example, a 20 mm lens on a Nikon D80 or D300 covers 70°, while a 200 mm lens covers only 8°.
With a long lens, then, if you move your camera 1° when pressing the shutter, that represents a significantly greater percentage of the image than with a wider angle lens, and will be more likely to cause blur. You can imagine that a faster shutter speed is required to freeze the motion to a smaller angle.
Also, as lenses get longer, they get heavier, making it even harder to hold steady.
On a camera without image stabilization, the rule of thumb for a safe, blur-free shutter speed is:
We say "effective" because most digital cameras have a sensor that is smaller than a 35mm film frame. As a result, the effective focal length of a lens is increased.
For example, the effective focal length of most Nikon DSLR's increases by a factor of 1.5 (and on Canons, by 1.6). A 200mm lens on a Nikon D90 has an effective focal length of 300mm, so the minimum safe shutter speed is 1/300 second. You would use 1/320 sec. because that is the fastest shutter speed that is equal to or faster than 1/300 sec.
In the photo below, I tried shooting at 1/40 second (three stops slower than recommended), without stabilization turned on. The rule of thumb must work, because the image, shown at 100% pixel size, is blurry.
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Nikon D300, 70-200mm VR @ 200mm, ISO 800, 1/40s, f/3.5.
Image of an amplifier faceplate shot with VR (Nikon Vibration Reduction) turned "off" and showing significant blur. Image is shown at 100% pixel size.
This was taken from a sitting position with both elbows braced on thighs.
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An Example With Stabilization
Today's image stabilization systems decrease the safe shutter speed by a factor of 2, 3, or 4 stops. For the 200mm lens that normally requires 1/320 sec., you could shoot at 1/80 sec., 1/40 sec., and maybe (cautiously) at 1/20 sec.
Look at the impact of turning stabilization "on" for the same subject and exposure.
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Nikon D300, 70-200mm VR @ 200mm, ISO 800, 1/40s, f/3.5.
Same image from same sitting position, with VR turned "on", which nearly eliminates the blur.
Image is shown at 100% pixel size.
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Had I not taken these both from a sitting position, with my elbows braced on my thighs, I may not have gotten this degree of sharpness at 3 stops below normal, much less at 4. Still, the improvement from stabilization is very noticeable.
What Stabilization Won't Do for You
Remember that stabilization compensates for camera movement, avoiding blur caused by your body, hand, and finger motion while snapping the shutter. On the other hand, stabilization does not compensate for subject motion.
If you have a fast-moving subject, even if you can effectively hold the camera still at 1/30 second the subject will still be blurry. If that is the effect you are after, go for it. Just be aware that stabilization steadies the camera, not the subject.
Stabilization - What's in a Name?
Camera makers use a variety of names to distinguish their brands. Here are the most common names in use today:
- Image stabilization - used by Canon, Sony, and Olympus
- Vibration reduction - used by Nikon
- Optical stabilization - used by Sigma
- Shake reduction - used by Pentax
While the results in reducing blur from camera motion is similar from the various manufacturers, they use different methods to achieve the reduction. On the next page, we take a quick peek behind the scenes of image stabilization.
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