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1. Optical compensation zoom system: When several sets of lenses are used for zooming and compensating in the zoom objective lens, the movement of each lens group is performed at the same direction, so that it is only necessary to connect the lens groups together in a simple mechanical structure for linear operation. Since the optical compensation zoom system cannot completely compensate for the image plane displacement, the moving group must be moved to a certain special position to obtain a stable and clear image surface, and the focal length is difficult to achieve continuous change, but several discrete values, so the usage is limited. However, it simplifies the mechanical structure and is beneficial to control the accuracy of the optical axis; and only uses a set of electromechanical control systems to achieve zooming and focusing, thereby reducing the cost and weight of the system, but the design difficulty is relatively large.