Zoom lens system

Claim 2

A zoom lens system made substantially according to the following table:

Claim 3

The zoom lens system of claim 1 wherein the characteristics set forth in the following table hold substantially true at the various focal lengths.

Claim 4

The zoom lens system of claim 1 wherein the sum of three variable spacings S1, S3 and S4 is 38.607 mm.

Claim 5

A zoom lens system made in accordance with claim 1 wherein lens elements I, II and III are a mean index of refraction (Ne) of approximately 1.6256 and a Nu value ( Nu ) of 57.79, lens elements IV and VIII have a means index of refraction (Ne) of 1.8127 and a Nu value ( Nu ) of 25.24, and lens elements V, VI and VII have a mean index of refraction (Ne) of 1.6940 and a Nu value ( Nu ) of 54.48.

Claim 6

A zoom lens system comprising a front section and a rear section, said front section consisting of four lens elements made substantially according to the following table:

Claim 7

A zoom lens system comprising a front section and a rear section, said front section consisting of four lens elements made substantially according to the following table:

Claim 8

The zoom lens system of claim 5 wherein the characteristics set forth in the following table hold substantially true at the various focal lengths for the system:

Claim 9

A zoom lens system comprising a front section and a rear section, said front section including a fixed lens barrel having a bore with a longitudinal first guide means and a circumferential spiral shaped first cam slot, said fixed lens barrel carrying a fixed front lens member, a drive barrel mounted for rotation circumjacent said fixed lens barrel and having a bore with a longitudinal second guide means, a movable rear lens barrel slidably mounted within the bore of said fixed lens barrel and carrying a rear lens member, said movable rear lens barrel having a circumferential arcuate second slot, a first cam follower attached to and extending radially outwardly from said movable rear lens barrel, said first cam follower extending extending through said first cam slot in said fixed lens barrel and into guiding contact with the longitudinal second guide means in said drive barrel bore, whereby rotation of said drive barrel relative to said fixed lens barrel will cause said first cam follower to move within said spiral shaped first cam slot and will cause corressponding rotational and axial sliding movement of said movable lens barrel within said fixed lens barrel, an interior lens mount slidably movable within the bore of said movable lens barrel and carrying an intermediate lens assembly, a second cam follower attached to and extending radially outwardly from said interior lens mount, said second cam follower extending through said second cam slot in said movable lens barrel and into guiding contact with the longitudinal first guide means in said fixed lens barrel bore, whereby rotation of said movable rear lens barrel will cause relative movement of said second cam slot and said second cam follower and will cause corresponding axial movement of said interior lens mount and said intermediate lens assembly carried thereby toward and away from said rear lens member carried by said movable rear lens barrel, the relative movement between said intermediate lens assembly and said rear lens member being governed by the configuration of said second cam slots and being such that the back focal length of the system will remain constant as the intermediate lens assembly and the rear lens member are moved toward and away from the front lens member, said rear section having a plurality of lens elements and means mounting said elements in fixed position rearwardly of said rear lens member of said front section.

Claim 10

A zoom lens system comprising a front section and a rear section, said front section including a fixed lens barrel having a bore with a longitudinal first guide means and a circumferential spiral shaped first cam slot, said fixed lens barrel carrying a fixed front lens member, a drive barrel mounted for rotation circumjacent said fixed lens barrel and having a bore with a longitudinal second guide means, a movable rear lens barrel slidably mounted within the bore of said fixed lens barrel and carrying a rear lens member, said movable rear lens barrel having a circumferential arcuate second slot, a first cam follower attached to and extending radially outwardly from said movable rear lens barrel, said first cam follower extending extending through said first cam slot in said fixed lens barrel and into guiding contact with the longitudinal second guide means in said drive barrel bore, whereby rotation of said drive barrel relative to said fixed lens barrel will cause said first cam follower to move within said spiral shaped first cam slot and will cause corressponding rotational and axial sliding movement of said movable lens barrel within said fixed lens barrel, an interior lens mount slidably movable within the bore of said movable lens barrel and carrying an intermediate lens assembly, a second cam follower attached to and extending radially outwardly from said interior lens mount, said second cam follower extending through said second cam slot in said movable lens barrel and into guiding contact with the longitudinal first guide means in said fixed lens barrel bore, whereby rotation of said movable rear lens barrel will cause relative movement of said second cam slot and said second cam follower and will cause corresponding axial movement of said interior lens mount and said intermediate lens assembly carried thereby toward and away from said rear lens member carried by said movable rear lens barrel, the relative movement between said intermediate lens assembly and said rear lens member being governed by the configuration of said second cam slots and being such that the back focal length of the system will remain constant as the intermediate lens assembly and the rear lens member are moved toward and away from the front lens member, said rear section having a plurality of lens elements and means mounting said elements in fixed position rearwardly of said rear lens member of said front section.

Claim 11

The zoom lens system of claim 7 wherein the front lens member, comprises a single biconcave lens element I, the intermediate lens assembly comprises a doublet of a plano-convex lens element II and a biconvex lens element III and the rear lens member comprises a single biconcave lens element IV and said lens element have the following characteristics: