Pinch zoom

Hello, I am making upgrade of pinch zoom, which will on camera size increasing move camera higher, and on camera size decreasing move camera lower... I tried to do this upgrade but when is display touched by two fingers, the position of camera go automatically higher and ignores any gestures. Please, help me. :)

 void Update()
     {
         // If there are two touches on the device...
         if (Input.touchCount == 2) {
             // Store both touches.
             Touch touchZero = Input.GetTouch (0);
             Touch touchOne = Input.GetTouch (1);
         
             // Find the position in the previous frame of each touch.
             Vector2 touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
             Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;
 
             // Find the magnitude of the vector between the touches in each frame.
             float prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
             float touchDeltaMag = (touchZero.position - touchOne.position).magnitude;
 
             // Find the difference in the distances between each frame.
             float deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;

             //===========================================================>>
             transform.Translate (new Vector2(0,prevTouchDeltaMag) *moveSpeed);
            //<<===========================================================
 
             // If the camera is orthographic...
             if (GetComponent<Camera>().orthographic) {
                 // ... change the orthographic size based on the change in distance between the touches.
                 GetComponent<Camera>().orthographicSize += deltaMagnitudeDiff * orthoZoomSpeed;
 
                 // Make sure the orthographic size never drops below zero.
                 GetComponent<Camera>().orthographicSize = Mathf.Max (GetComponent<Camera>().orthographicSize, 0.1f);
         }
     }