The 2-axis rigid camera mounts for the slide camera, to ensure that it is always locked into the same position pointed at the projection screen. The ability to finely adjust the roll position of the camera makes it much easier to set the slide camera image absolutely square with the projection screen. Fine adjustments are made using a hex wrench, allowing for extremely fine positioning. All adjustments and locking are made with a single hex wrench. A key element to keeping the spotting camera image aligned with the tracking camera is to guarantee that once the spotting camera is positioned, it does not move.