High precision movement of telescope mirrors in two-mirror telescopes is examined. Active optics are used for high precision movement of M2 during exposures to introduce a specific amount of decentering coma. It is shown that the decentering coma may be controlled by high accuracy rotation of the mirror around a point near the center of curvature of M2. Basic equations are developed for the displacement of the barycenter of the geometric blur. A relation is obtained for determining the correct position around which the rotation should be performed. The application of these techniques to two-mirror telescopes is discussed. Ray tracing and analytical results were compared and showed good agreement.