Back focus controlling device in optical systems

摘要

A lens focus controlling device for an optical system includes a first cylindrical cam having a cam face formed on at least one end thereof, a second cylindrical cam having a cam face on one end thereof slidably disposed in contact with said first cam face over a predetermined range, a lens group secured to said second cylindrical cam, a stop member operatively engageable with said lens group to prevent rotation while allowing reciprocation of said lens group along the optical axis thereof and a drive system for rotating said first cylindrical cam relative to said second cylindrical cam.