Taking stable and sharp photos is hard in some situations. For example when taking a photo using high zoom lenses even the tiniest camera movement will result in a blurry photo. The reason for that blurriness is that while the shutter is open and the photo is being captured the camera moves and the image on the sensor also moves losing its sharpness. Image stabilizers help in solving the problem, here is how.The best solution for camera movements is of course to eliminate the movements. Sometimes this can be accomplished by using a tripod or placing the camera on a stable surface when taking the photo. However in many situation it is impossible to completely stabilize the camera - for example when taking photos of fast objects in high zoom.
When movement elimination is not possible other solutions can be used that instead of preventing the movement compensate for it and prevent its symptom: blurry photos. Such solutions are also known as Image Stabilizers.
There are many different implementations of image stabilizers and many manufacturers keep their implementation details secret to prevent competitors from copying it. An image stabilizer implementation can be divided to two: detecting the movement and compensating for it. Detection is the mechanism that detects that the camera moved while shooting a photo. Compensation is the mechanism that for detected movements compensates to prevent the movement symptoms.
There are two common ways to implement image stabilizers (sometimes known as mechanical image stabilizers for the implementation mechanical feature): a floating lens element or a moving sensor.
Floating lens element: An element is added in the lenses usually in the form of a compensating lens. This element is “floating” in the lenses and can move left, right, up and down. Gyroscopes are placed in the lenses - or micro gyroscopes or equivalent sensors. When the camera moves the gyroscopes detect the movement and send a signal to the floating lens to move in the right direction in order to compensate for the movement. Moving the lens corrects the angle in which the light hits the image sensor compensating for the movement.
Moving sensor: The sensor is a chip behind the lenses that converts the light reflected on it to digital pixels. When a movement is detected the sensor is slightly moved in the opposite direction to compensate for it. Gyroscopes or equivalent sensors could be used to detect movements though many stabilizers use a DSP processor that analyzes the image on the sensor in real time to detect movements eliminating the need of another mechanical part
The advantages of such stabilizers are: getting sharper photos while practically eliminating blurriness in most common scenarios. Sensor based detectors work very well in low light scenarios since they detect actual physical movement while DSP processors based detection is less effective in low light scenarios and more prone to errors. The disadvantages are: added cost, weight and size to the camera as a result of the mechanical mechanism.
http://www.camera2photo.com/2006/09/03/still-digital-camera-image-stabilizers-keep-your-images-sharp/
