Abstract A zoom ring is provided for a zoom lens, the ring being made of at least two members; a cylindrical member including a rotational limit stop and provided with cam slots, and a curved member or plate formed with matching cam slots. The cam slots in both members register with each other when the curved plate is positioned on the cylindrical member by means of pin connections, the cam slots in the cylindrical member being relieved while the plate cam slots are accurately machined. In zoom lens systems, the zoom lens or lenses are shifted longitudinally with respect to the optical axis of the objective by means of a cam ring having formed therein, cam grooves which may be either curved or straight grooves. The cam grooves are machined individually to close tolerances to provide accurate focusing, particularly when two lens elements of the objective are separately movable. The zooming cam ring is further provided with a stop member, either in the form of a pin or projection and which may be integrally formed with the ring, to prevent rotation of the ring beyond a predetermined angle and to provide a positive limit for the focusing plane of the objective. Such rings in the past have been manufactured on an individual basis due to the close tolerances required in forming the cam grooves and in setting the stop member. In addition, the wearing down or breaking of the cutting tools led to further complications in providing an accurately machined cam ring suitable for optical work.
A lens barrel for a zoom lens system, comprising in combination a cylindrical member, a stop member on said cylindrical member for limiting the angle of rotation of the cylindrical member, a thin pressed curved plate formed with positioning openings, positioning pins secured on the peripheral outer surface of said cylindrical member, the positioning openings in said curved plate receiving said positioning pins when said pressed curved plate is assembled on said cylindrical member, relieved grooves provided in said cylindrical member, and cam grooves accurately made to close tolerances in said curved plate registering with said relief grooves to permit the passage of cam pins of lens components of the zoom lens system therethrough.
Claim 2
Dependent Claim
114 words
A lens barrel for a zoom lens system, comprising in combination a cylindrical member, a stop member on said cylindrical member for limiting the angle of rotation of the cylindrical member, a thin pressed curved plate formed with positioning openings, positioning pins secured on the peripheral outer surface of said cylindrical member, the positioning openings in said curved plate receiving said positioning pins when said pressed curved plate is assembled on said cylindrical member, relieved grooves provided in said cylindrical member, and cam grooves accurately made to close tolerances in said curved plate registering with said relief grooves to permit the passage of cam pins of lens components of the zoom lens system therethrough.
Claim 3
Dependent Claim
18 words
A lens barrel according to claim 1, wherein said stop member is separately securable to said cylindrical member.