Image stabilization is used in zoom lenses to counteract the blur caused by camera movement.
Image stabilization is also called vibration reduction.
As you increase the magnification, by increasing the focal length, even a slight camera movement creates blur.
When using focal lengths larger than about 100mm, you have to:
• Use fast shutter speeds.
As focal length increases, a faster shutter speed is required.
• Use higher ISO settings.
The above two conditions are problematic if there's little light.
On on overcast day, you may not be able to photograph at f/4 at 1,000th of a second, even if you set the ISO to 800.
And, you may not want the increased noise of higher ISO settings.
With image stabilization, you can use lower shutter speeds.
And, you can use lower ISO settings.
Also, if you're using flash with a slow shutter speed, image stabilization will prevent blur from camera movement.
The Night Portrait exposure mode uses a slow shutter speed, for example.
Gyroscopes are used to move a lens or the sensor.
For example, when the camera moves to the left, the gyroscope moves a lens or the sensor to the right.
Digital stabilization isn't image stabilization.
It doesn't counteract camera movement.
Instead, when a moving subject is detected by the camera, the ISO will be increased, allowing faster shutter speeds.
Digital stabilization is also called anti-shake.
Panning is when you follow a moving subject, and use slow a shutter speed.
The result is a sharp subject against a blurry background.
If you use panning, make sure you purchase a lens or camera where you can turn off image stabilization on the horizontal axis.
Image stabilization will only correct movement on the vertical axis.