In the TV camera system that zoom voltage is obtained by potentiometer,three access methods of deviation angle of the method are introduced.First,the traditional look-up table method introduced obtaining target coefficient of deviation angle,and pointed out the inadequacies of their accuracy.Then,according to the principle of optical imaging is derived from the goal of real-time measurement formula for calculating the deviation angle,and pointed out the difficulty of its realization;voltage at the end of a fixed focal length,with the goal of the angular deviation from the target of TV is a linear relation between the characteristics,the use of servo system encoder output of the true perspective of precision calibration coefficient of deviation angle through the curve to find an easy way to achieve the angular deviation coefficients formula.Use angle encoder calibration coefficient of deviation of the long focal length of high-precision tracking system was satisfactory results.