Image stabilization (IS).
(Canon) A complex computerized system built into a number of lenses sold by Canon, which allows the lens to compensate for small camera movements. IS lenses contain gyroscopic sensors to detect motion and small motors which physically shift a moving lens element or group to compensate appropriately.
IS lenses are, therefore, useful when handholding in low-light situations - they essentially give you a stop or two extra. ie: they let you handhold the camera and use slower shutter speeds than you would be able to normally. They arent useful when theres a lot of subject motion, however. Nikons equivalent technology is called VR, for vibration reduction.
Note that some camcorders use a system of digital image stabilization which does not involve any moving lens elements. Instead the cameras computer analyzes each frame and moves data around the field to compensate for camera movement. Such systems offer inferior results to true optical image stabilizing.
cf. element, group, VR.
Entry last updated 2002-04-03. Term 634 of 1487.
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