Compact eight element zoom lens with optical compensation

Claim 2

A zoom lens the optical portion of which consists, in an axially aligned arrangement from the long conjugate side to the short conjugate side, of: a negative first lens component having a convex surface toward said long conjugate; a positive second lens component; a positive third lens component, having a convex surface toward said long conjugate, adjacent to said positive second lens component; a negative fourth lens element; a positive fifth lens component with unequally curved surfaces having its weaker curvature toward said long conjugate; a positive sixth lens component having a strong curvature toward said long conjugate; a negative seventh lens element with unequally curved surfaces having its weaker curvature toward said long conjugate; and a positive eighth lens component.

Claim 3

The zoom lens described in claim 1, the mechanical portion of which includes means for permitting said second, third, and fifth lens components to move axially between said first and sixth lens components without changing the separation either between said second and third lens components or between said third and fifth lens components and without changing the separation between said first lens component and said fourth lens element.

Claim 4

The zoom lens described in claim 1, wherein said first, second, third and fifth lens components and said fourth lens element function as a zoom group to change the focal length of said zoom lens and said sixth, and eighth lens components and said seventh lens element function as an objective group, the lens powers of said zoom group selected so light emerging therefrom will be refracted to a focus at a finite distance behind said zoom group, and the powers and shapes of said objective group selected to correct the aberrations in said focused light entering said objective group.

Claim 5

The zoom lens described in claim 1, wherein the movable positive lens components of the zoom group have Abbe dispersion numbers greater than 60.

Claim 6

The zoom lens described in claim 1, wherein the overall length of said zoom lens from the first refracting surface to the last refracting surface is less than four times its shortest focal length.

Claim 7

A zoom lens the optical portion of which consists, in an axially aligned arrangement from the long conjugate side to the short conjugate side, of: a meniscus negative first lens component having its convex side toward said long conjugate; a biconvex positive second lens component; a meniscus positive third lens component, having its convex side toward said long conjugate, adjacent to said biconvex positive second lens component; a biconcave negative fourth lens element; a biconvex positive fifth lens component with unequally curved surfaces having its weaker curvature toward said long conjugate; a biconvex positive sixth lens component having a strong curvature toward said long conjugate; a biconcave negative seventh lens element with unequally curved surfaces having its weaker curvature toward said long conjugate; and a positive eighth lens component.

Claim 8

A zoom lens the optical portion of which consists, in an axially aligned arrangement from the long conjugate side to the short conjugate side, of: a meniscus negative first lens component having its convex side toward said long conjugate; a biconvex positive second lens component; a meniscus positive third lens component, having its convex side toward said long conjugate, adjacent to said biconvex positive second lens component; a biconcave negative fourth lens element; a biconvex positive fifth lens component with unequally curved surfaces having its weaker curvature toward said long conjugate; a biconvex positive sixth lens component having a strong curvature toward said long conjugate; a biconcave negative seventh lens element with unequally curved surfaces having its weaker curvature toward said long conjugate; and a positive eighth lens component.

Claim 9

A zoom lens for refracting an image of a subject located in front of it to a focal plane at its rear, the optical portion of which consists of: a zoom group consisting of a negative lens element stationary with respect to said focal plane, a plurality of three positive lens elements, said plurality of positive lens elements being disposed on both sides of said negative lens element along a common axis therewith, and also being movable axially with respect to said negative lens element, a meniscus negative lens element disposed on said axis forward of said plurality of positive lens elements; and an objective group consisting of three individual lens elements disposed on said axis, rearward of said plurality of positive lens elements, said plurality of positive lens elements movable conjointly so as to substantialLy change the focal length of said zoom lens without shifting said image from said focal plane, said zoom lens having an overall length from its first refracting surface to its last refracting surface less than four times its shortest focal length.

Claim 10

A zoom lens for refracting an image of a subject located in front of it to a focal plane at its rear, the optical portion of which consists of: a zoom group consisting of a negative lens element stationary with respect to said focal plane, a plurality of three positive lens elements, said plurality of positive lens elements being disposed on both sides of said negative lens element along a common axis therewith, and also being movable axially with respect to said negative lens element, a meniscus negative lens element disposed on said axis forward of said plurality of positive lens elements; and an objective group consisting of three individual lens elements disposed on said axis, rearward of said plurality of positive lens elements, said plurality of positive lens elements movable conjointly so as to substantialLy change the focal length of said zoom lens without shifting said image from said focal plane, said zoom lens having an overall length from its first refracting surface to its last refracting surface less than four times its shortest focal length.

Claim 11

The zoom lens described in claim 7, wherein said negative lens elements and said plurality of positive lens elements, of said zoom group, coact to form a real image at a finite conjugate to the rear of said zoom lens and said objective group refracts said real image to a focus at said focal plane.

Claim 12

The zoom lens described in claim 7, wherein said objective group consists of: a positive lens element with a substantially stronger curvature on its forward refracting surface than on its rearward refracting surface; a biconcave negative lens element with a weaker curvature on its forward refracting surface than on its rearward refracting surface; and a last positive lens element with a convex forward refracting surface, said lens elements of said objective group arranged in the foregoing order with said last positive lens element closest to said focal plane.

Claim 13

The zoom lens described in claim 7 wherein said three positive lens elements consist of: a forward biconvex positive lens element; a meniscus positive lens element having its convexly curved refracting surface adjacent the rearward refracting surface of said biconcave positive lens element; and a rearward biconvex positive lens element separated from said meniscus positive lens element by said stationary negative lens element.

Claim 14

The zoom lens described in claim 10 the mechanical portion of which includes means for retaining a predetermined spacing arrangement between said three positive lens elements and for moving them as a unit relative to the other lens elements to change the focal length of said zoom lens.

Claim 15

The zoom lens described in claim 7, wherein said positive lens elements have Abbe dispersion numbers greater than 60.

Claim 16

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table:

Claim 17

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table:

Claim 18

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table:

Claim 19

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table:

Claim 20

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table:

Claim 21

An optically compensated eight element zoom objective lens having the design parameters for a unit focal length, F, represented in the following table: