The next big step was taken by Canon and Nikon when they introduced the 300mm f2.8 in the late seventies. This lens allowed photojournalists, especially sports photographers, to reach out and capture decisive moments from over 50 feet away and do it within the range of the available film emulsion speeds. The stabilizer contains two tiny solid-state gyro sensors that are installed in the lens elements. Unlike old fashioned gyros that were large, heavy, externally mounted devices that require ample power and a lengthy delay for warm up, Canon's image stabilizer mechanism fits in the the lens. It is powered by the camera, and becomes fully functional within a second of activation.
Sensors can detect angular velocity changes in the relationship of the camera to the subject.
When the sensors detect yaw and pitch, they pass angular velocity signals to a 16-bit microprocessor that in turn controls a magnetic coil that shifts a group of lens elements parallel to the focal plane in direct response to the direction and degree of movement. The results can be seen in this recent photo of President Clinton. What this means is that the news photographer who had been lugging around a 300mm f.28 can now drop half the weight and go to the new lens that does the same thing as far as capturing the image. Granted, this does not apply to sports photographers, who still need all the speed they can get from an optic. But, for the average news photographer, it means a lot less weight.