Internal focusing telephoto lens

Claim 2

A telephoto lens of fixed equivalent focal length comprising from the front end to the rear end: a first positive group; a second negative group comprising a doublet including a positive element and a biconcave element; and a third positive group and a fourth negative group; said first, third, and fourth groups being stationary in said lens;

Claim 3

said second group being axially movable for focusing of said lens.

Claim 4

said second group being axially movable for focusing of said lens.

Claim 5

The telephoto lens of claim 1 wherein said third and fourth groups each comprise a single element.

Claim 6

The telephoto lens of claim 1 wherein said first group comprises a biconvex element and a doublet including a biconvex element.

Claim 7

The telephoto lens of claim 3 wherein said negative elements of said first and second groups have Q-values less than negative 50.

Claim 8

The telephoto lens of claim 3 wherein said biconvex elements of said first group have Q-values greater than 15.

Claim 9

The telephoto lens of claim 1 wherein said positive element of said second group has a Q-value greater than 80.

Claim 10

The telephoto lens of claim 1 defined by substantially the following specification: ______________________________________ Axial Distance Index of Abbe Radius of Between Refrac- No. Element Curvature (mm) Surfaces (mm) tion N.sub.D V.sub.D ______________________________________ R1 = 129.059 L1 9.31 1.51823 58.96 R2 = -208.333 0.30 R3 = 108.584 L2 10.37 1.51823 58.96 R4 = -140.226 L3 4.00 1.74950 35.04 R5 = 159.606 86.18 R6 = Plano L4 7.00 1.78472 25.70 R7 = -65.463 L5 2.50 1.83500 42.98 R8 = 105.958 37.49 R9 = -471.233 L6 4.04 1.51742 52.15 R10 = -47.239 18.36 R11 = -36.628 L7 2.50 1.77250 49.62 R12 = -94.946 ______________________________________ where the first column lists the lens elements numerically commencing at the front end of the lens, the second column lists the radii of curvature in millimeters for the respective surfaces of the elements numbered from the front to the rear with positive values of the radii indicating surfaces which are convex to the front and negative values radii which are concave to the front, the third column lists the axial distances between surfaces in millimeters, the fourth column lists the refractive index N D of the elements and the fifth column lists the dispersive index V D of the Abbe number of the element.

Claim 11

The telephoto lens of claim 1 defined by substantially the following specification: ______________________________________ Axial Distance Index of Abbe Radius of Between Refrac- No. Element Curvature (mm) Surfaces (mm) tion N.sub.D V.sub.D ______________________________________ R1 = 127.620 L1 9.33 1.518.23 58.96 R2 = -210.793 0.30 R3 = 106.588 L2 10.40 1.518.23 58.96 R4 = -142.093 L3 4.00 1.74950 35.04 R5 = 153.781 87.25 R6 = -568.303 L4 5.22 1.84666 23.83 R7 = -83.591 L5 2.50 1.80420 46.50 R8 = 114.412 37.84 R9 = -302.198 L6 3.94 1.51742 52.15 R10 = -46.050 16.04 R11 = -36.198 L7 2.50 1.77250 49.62 R12 = -88.159 ______________________________________ where the first column lists the lens elements numerically commencing at the front end of the lens, the second column lists the radii of curvature in millimeters for the respective surfaces of the elements numbered from the front to the rear with positive values of the radii indicating surfaces which are convex to the front and negative values radii which are concave to the front, the third column lists the axial distances between surfaces in millimeters, the fourth column lists the refractive index N D of the elements and the fifth column lists the dispersive index V D of the Abbe number of the element.

Claim 12

The telephoto lens of claim 1 defined by substantially the following specification: ______________________________________ Axial Distance Index of Abbe Radius of Between Refrac- No. Element Curvature (mm) Surfaces (mm) tion N.sub.D V.sub.D ______________________________________ R1 = 125.105 L1 9.33 1.5182 58.96 R2 = -218.174 0.30 R3 = 98.207 L2 10.50 1.5182 58.96 R4 = -154.827 L3 4.00 1.7495 35.04 R5 = 137.286 101.63 R6 = 1817.923 L4 3.21 1.84666 23.83 R7 = -59.743 L5 2.50 1.83500 42.98 R8 = 70.097 37.56 R9 = -1307.707 L6 4.87 1.51742 52.10 R10 = -39.278 9.00 R11 = -33.497 L7 2.50 1.83500 42.98 R12 = -77.679 ______________________________________ where the first column lists the lens elements numerically commencing at the front end of the lens, the second column lists the radii of curvature in millimeters for the respective surfaces of the elements numbered from the front to the rear with positive values of radii indicating surfaces which are convex to the front and negative values radii which are concave to the front, the third column lists the axial distances between surfaces in millimeters, the fourth column lists the refractive index N D of the elements and the fifth column lists the dispersive index V D of the Abbe number of the element.

Claim 13

The telephoto lens of claim 1 defined by substantially the following specification: ______________________________________ Axial Distance Index of Abbe Radius of Between Refrac- No. Element Curvature (mm) Surfaces (mm) tion N.sub.D V.sub.D ______________________________________ R1 = 130.095 L1 9.29 1.5182 58.96 R2 = -206.993 0.30 R3 = 103.224 L2 10.48 1.5182 58.96 R4 = -144.685 L3 4.00 1.7495 35.04 R5 = 152.525 80.70 R6 = -756.922 L4 12.00 1.84666 23.83 R7 = -87.747 L5 2.50 1.80420 46.50 R8 = 110.923 37.61 R9 = -274.269 L6 3.90 1.51742 52.10 R10 = -44.799 15.33 R11 = -35.219 L7 2.50 1.77250 49.62 R12 = -90.351 ______________________________________ PG,24 where the first column lists the lens elements numerically commencing at the front end of the lens, the second column lists the radii of curvature in millimeters for the respective surfaces of the elements numbered from the front to the rear with positive values of the radii indicating surfaces which are convex to the front and negative values radii which are concave to the front, the third column lists the axial distances between surfaces in millimeters, the fourth column lists the refractive index N D of the elements and the fifth column lists the dispersive index V D of the Abbe number of the element.

Claim 14

The telephoto lens of claim 1 defined by substantially the following specification: ______________________________________ Axial Distance Index of Abbe Radius of Between Refrac- No. Element Curvature (mm) Surfaces (mm) tion N.sub.D V.sub.D ______________________________________ R1 = 147.960 L1 9.78 1.57250 57.49 R2 = -280.940 0.30 R3 = 100.840 L2 10.07 1.57250 57.49 R4 = -176.771 L3 4.00 1.74950 35.04 R5 = 129.663 93.09 R6 = Plano L4 10.45 1.78472 25.70 R7 = -85.845 L5 2.50 1.77250 49.62 R8 = 78.526 37.69 R9 = -269.503 L6 4.63 1.51742 52.10 R10 = -35.947 6.31 R11 = -32.224 L7 2.50 1.66672 48.30 R12 = -81.672 ______________________________________ where the first column lists the lens elements numerically commencing at the front end of the lens, the second column lists the radii of curvature in millimeters for the respective surfaces of the elements numbered from the front to the rear with positive values of the radii indicating surfaces which are convex to the front and negative values radii which are concave to the front, the third column lists the axial distances between surfaces in millimeters, the fourth column lists the refractive index N D of the elements and the fifth column lists the dispersive index V D of the Abbe number of the element.