Cam focusing system for optical instruments

Claim 1

A CAM FOCUSING OPTICAL INSTRUMENT HAVING A LENS, COMPRISING, IN COMBINATION, AN AXIALLY MOVABLE BARREL IN WHICH SAID LENS IS MOUNTED, A TUBULAR GUIDE FOR SAID BARREL, AT LEAST ONE LATERALLY PROJECTING CAM FOLLOWER CONNECTED TO SAID BARREL AND EXTENDING TRANSVERSELY OUTWARDLY THEREFROM, A CYLINDRICAL CAM RING HAVING A CONTINUOUS CAM TRACK, SAID CAM RING HAVING TWO LONGITUDINALLY SPACED PARTS MOVABLE AXIALLY RELATIVE TO ONE ANOTHER, THE LONGITUDINAL SPACING BETWEEN SAID PARTS COMPRISING A CAM GROOVE DEFINING SAID CAM TRACK INTO WHICH SAID CAM FOLLOWER EXTENDS, MEANS FOR SELECTIVELY CHANGING THE RANGE OF SAID OPTICAL INSTRUMENT BY ROTATION OF SAID CAM RING WHEN SAID PARTS ARE NOT PRESSED IN AXIAL BINDING RELATION AGAINST SAID CAM FOLLOWER, AND MEANS FOR PRESSING SAID CAM PARTS TOWARD ONE ANOTHER TO BIND SAID CAM FOLLOWER IN THE LAST SELECTED RANGE POSITION FOR SAID OPTICAL INSTRUMENT.