The focusing mechanism in Taylor Hubson could focus from infinity down to the target on the face of its front barrel (right). It uses a rack and pinion mechanism (above) that internally focuses the telescope to such large range. The advantage on this capability in doing alignments is obvious. In conjunction with a precisely aligned mirror mounted on its measuring surface, it can be utilized to align cent ration of bearings on engine crankshafts, optical instrumentation, granite tables, motorized stages, etc.