THE EDGE OF THE PROJECTED SPOT is focused by rotating the focus control knob.
This focus control alters the relative distance between the lenses to adjust the optical system for differing lengths
of throw. The degree of torque required to rotate the focus control is adjustable by tightening or loosening the
friction screws (Figure 4, Item 17) on the off-operator side of the focus mechanism. When making a focus
adjustment, observe the spot and rotate the focus knob until the sharpest edge on the projected spot is obtained.