What is Optical Image Stabilizer? One is Vari-Angle Prism Image Stabilizer and Canon has added a new breakthrough technology “Optical Shift Image Stabilizer” DIGISUPER 100 xs, 86II xs, 86II TELE xs, 75 xs, HJ40x10B IASD-V, HJ40x14B IASD-V are equipped with Optical Shift IS. How the Optical Shift Image Stabilizer Works The Optical Shift Image Stabilizer (IS) shifts a lens group in parallel to the image plane. When the lens moves, the light rays from the subject are bent relative to the optical axis, resulting in a blurred image because the light rays are deflected. By shifting the IS lens group on a plane perpendicular to the optical axis to counter the degree of image shake, the light rays reaching the image plane can be steadied. Figure shows what happens when the there is a downward movement with the lens. The center of the image moves downward on the image plane. When the IS lens group shifts on the vertical plane, the light rays are refracted so that the image center returns to the center of the image plane. Since image shake occurs in both horizontal and vertical directions, the IS lens group can shift horizontally and vertically on a plane perpendicular to the optical axis to counteract the image shake. Two shake-detecting sensors, one each for yaw and pitch, are used to detect lens movement. The shake-detecting sensors detect the angle and speed of movement and send this information to a high-speed 32-bit microcomputer. The microcomputer then converts the detection signals into drive signals for the IS lens group. In accordance with the drive signals, the IS lens group actuator moves the IS lens group and thus counteracting the image shake and maintaining a stable picture. Shift IS and Vari-Angle Prism Image Stabilizer In comparison with the Optical Vari-Angle Prism IS where the IS unit must be located in the front of the lens, shift IS allows the IS lens group to be built internally in the lens which allows for a compact design and lighter weight. Vari-Angle Prism IS as used in our ENG lenses, covers a slightly wider bandwidth of frequencies including higher frequencies that are often encountered with moving vehicles such as helicopters. Shift IS is most effective for lower frequency movements caused by hand shake, platform vibration or wind effect without increasing the overall size of the lens.