High speed focusing telephoto lens

Claim 2

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance.

Claim 3

A high speed focusing telephoto lens according to claim 1, in which said movable sub-group has a most convergent surface convex toward the object.

Claim 4

A high speed focusing telephoto lens according to claim 1, in which said stationary sub-group has a most divergent surface concave toward the image.

Claim 5

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said stationary sub-group is arranged nearer an image than said movable sub-group.

Claim 6

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said stationary sub-group is arranged nearer an image than said movable sub-group.

Claim 7

A high speed focusing telephoto lens according to claim 4, in which said movable sub-group has a front surface convex toward the object, and said stationary sub-group has a rear surface concave to the image.

Claim 8

A high speed focusing telephoto lens according to claim 5, in which said movable sub-group consists of a plurality of lenses.

Claim 9

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said stationary sub-group and said movable sub-group each consist of at least one positive lens and at least one negative lens, the average Abbe number Vb 1 of the positive lenses in said stationary sub-group is smaller than the average Abbe number Vb 2 of the negative lenses, and the average Abbe number Va 1 of the positive lenses in said movable sub-group is larger than the average Abbe number Va 2 of the negative lenses.

Claim 10

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said stationary sub-group and said movable sub-group each consist of at least one positive lens and at least one negative lens, the average Abbe number Vb 1 of the positive lenses in said stationary sub-group is smaller than the average Abbe number Vb 2 of the negative lenses, and the average Abbe number Va 1 of the positive lenses in said movable sub-group is larger than the average Abbe number Va 2 of the negative lenses.

Claim 11

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said front lens group has a positive lens member, a negative lens member and a positive lens member, and is followed by a movable sub-group in axially spaced relation thereto; and on the image side of this movable sub-group is a negative stationary sub-group.

Claim 12

A high speed focusing telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group having a negative refracting power and consisting of at least one stationary sub-group and at least one movable sub-group having a positive refracting power, said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at near distance from its focusing on an object at far distance, and wherein said front lens group has a positive lens member, a negative lens member and a positive lens member, and is followed by a movable sub-group in axially spaced relation thereto; and on the image side of this movable sub-group is a negative stationary sub-group.

Claim 13

A telephoto lens according to claim 8, in which said movable sub-group and said stationary sub-group each consist of a bi-convex lens and a bi-concave lens.

Claim 14

A telephoto lens according to claim 8, in which said movable sub-group and said stationary sub-group each consist of a meniscus positive lens and a meniscus negative lens.

Claim 15

A telephoto lens comprising; a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group axially spaced from said front lens group, having a negative refracting power and consisting of at least one movable sub-group and a stationary sub-group; the convergent surface having the smallest radius of curvature in said movable sub-group is convex toward the object; and said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at infinite distance from its focusing on an object at finite distance.

Claim 16

A telephoto lens comprising; a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group axially spaced from said front lens group, having a negative refracting power and consisting of at least one movable sub-group and a stationary sub-group; the convergent surface having the smallest radius of curvature in said movable sub-group is convex toward the object; and said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at infinite distance from its focusing on an object at finite distance.

Claim 17

A telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group axially spaced from said front lens group, having a negative refracting power and consisting of at least one movable sub-group and another sub-group; the convergent surface having the smallest radius of curvature in said movable sub-group is convex toward the object; and said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at infinite distance from its focusing on an object at finite distance, and wherein between said movable sub-group and the image plane is a stationary sub-group, and the divergent surface having a smallest radius of curvature in this stationary sub-group is concave to the image plane.

Claim 18

A telephoto lens comprising: a front lens group which has a positive refracting power and remains stationary during focusing; and a rear lens group axially spaced from said front lens group, having a negative refracting power and consisting of at least one movable sub-group and another sub-group; the convergent surface having the smallest radius of curvature in said movable sub-group is convex toward the object; and said movable sub-group being moved on the optical axis toward an object so as to cause said telephoto lens to focus an object at infinite distance from its focusing on an object at finite distance, and wherein between said movable sub-group and the image plane is a stationary sub-group, and the divergent surface having a smallest radius of curvature in this stationary sub-group is concave to the image plane.

Claim 19

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group.

Claim 20

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group.

Claim 21

A telephoto lens according to claim 13, in which said movable sub-group has a positive refracting power, and the converging surface having a smallest radius of curvature in this sub-group is convex toward the object.

Claim 22

A telephoto lens according to claim 13, in which said primary lens part includes two positive lens members and a negative lens member; and the axial distance between said primary lens part and said movable sub-group is longer than that between said movable sub-group and said rearmost sub-group even when said movable sub-group is positioned at the front end of the focusing range.

Claim 23

A telephoto lens according to claim 15, in which said primary lens part consists of a positive lens, a negative lens and a positive lens.

Claim 24

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group, and wherein the diverging surface having a smallest radius of curvature in said rearmost sub-group is convex toward the object.

Claim 25

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group, and wherein the diverging surface having a smallest radius of curvature in said rearmost sub-group is convex toward the object.

Claim 26

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group, said primary lens part includes two positive lens members and a negative lens member; and the axial distance between said primary lens part and said movable sub-group is longer than that between said movable sub-group and said rearmost sub-group even when said movable sub-group is positioned at the front end of the focusing range, and wherein said movable sub-group consists of a positive lens having a front surface convex toward the object and a negative lens; and said rearmost sub-group consists of a positive lens and a negative lens having a rear surface concave toward the image.

Claim 27

A telephoto lens comprising: a primary lens part which consists of a plurality of lenses, which has a positive refracting power and which remains stationary during focusing; and a movable sub-group on the image side of said primary lens part, said movable sub-group being followed by a fixed rearmost sub-group, the compound reflection power of said movable sub-group and said rearmost sub-group being negative, whereby the focusing of said telephoto lens is effected by axially moving said movable sub-group, said primary lens part includes two positive lens members and a negative lens member; and the axial distance between said primary lens part and said movable sub-group is longer than that between said movable sub-group and said rearmost sub-group even when said movable sub-group is positioned at the front end of the focusing range, and wherein said movable sub-group consists of a positive lens having a front surface convex toward the object and a negative lens; and said rearmost sub-group consists of a positive lens and a negative lens having a rear surface concave toward the image.