Two element plastic zoom camera lens

Claim 2

A zoom camera lens for forming an image of a scene at an image plane consisting of a plastic negative power element, a plastic positive power element and a stop, in which both elements are movable with respect to each other and the image to vary focal length without varying the position of the image, in which the positive element is positioned between the negative plastic element and the stop, each element has two surfaces which are concave to the stop and the lens complies with the following inequalities: 0.5<f.sub.W /f.sub.N <1.05; and 0.5<f.sub.P /f.sub.W <1.05 where f W is the focal length of the lens at its wide angle position, f N and f P are the absolute values of the focal length of the negative element and of the positive element, respectively.

Claim 3

The zoom camera lens according to claim 1 wherein the negative element is between the positive element and the image.

Claim 4

The zoom camera lens according to claim 1 wherein the positive element is between the negative element and the image.

Claim 5

The zoom camera lens according to claim 1 having an image field which is curved.

Claim 6

The zoom camera lens according to claim 4 wherein the image field has a radius of curvature less than 500 mm.

Claim 7

The zoom camera lens according to claim 1 having at least one aspheric surface.

Claim 8

The zoom camera lens according to claim 6 wherein the aspheric surface is on the surface closest to the image.

Claim 9

The zoom camera lens according to claim 6 having at least three aspheric surfaces.

Claim 10

The zoom camera lens according to claim 8 wherein the aspheric surfaces are on the three surfaces closest to the image and the positive element is between the negative element and the image plane.

Claim 11

The zoom camera lens according to claim 6 wherein the two elements are made of a same material.

Claim 12

The zoom camera lens according to claim 10 wherein the material is methyl acrylate.

Claim 13

The zoom camera lens according to claim 6 wherein the positive element is made of methyl acrylate and the negative element is made of a material having an Abbe V number less than 40.

Claim 14

The zoom camera lens according to claim 1 wherein an area weighted average MTF of the lens at 10 lines per mm is in excess of 50 across a zoom range of at least 1.4 to 1.

Claim 15

The zoom camera lens according to claim 11 wherein said area weighted average is above 65 across a 1.4 to 1 zoom range.

Claim 16

The zoom camera lens according to claim 1 and constructed according to the following chart, wherein the surfaces are numbered from an object side to an image side, all distances are in millimeters, V is the abbe number, index is the index of refraction, and both V and the index are for the e line of the spectrum: __________________________________________________________________________ SURFACE RADIUS THICKNESS INDEX V __________________________________________________________________________ 1 163.530 2.000 1.492 57.4 2 ASPHERE A 3 9.17500 2.370 1.492 57.4 4 ASPHERE 5.650 DIAPHRAGM ASPHERIC EQUATION: ##STR5## SURF. 2 C = 0.0636092 D = 0.262E-05 F = 0.0 K = 0.091 E = -0.357E-07 G = 0.0 SURF. 4 C = 0.0240442 D = 0.319E-04 F = 0.341E-07 K = 0.0 E = -0.719E-06 G = -0.757E-09 ZOOM FOCAL BACK FRONT SPACING LENS STOP RELATIVE LENGTH FOCUS FOCUS (A) LENGTH DIAMETER APERTURE __________________________________________________________________________ 49.98 54.17 39.10 4.956 9.326 3.53 13.75 41.80 48.79 26.67 8.180 12.550 3.51 12.30 35.01 44.33 16.35 12.000 16.370 3.52 11.00 __________________________________________________________________________

Claim 17

The zoom camera lens according to claim 1 and constructed according to the following chart, wherein the surfaces are numbered from an object side to an image side, all distances are in millimeters, V is the abbe number, index is the index of refraction, and both V and the index are for the e line of the spectrum: __________________________________________________________________________ SURFACE RADIUS THICKNESS INDEX V __________________________________________________________________________ 1 44.0730 2.000 1.492 57.4 2 ASPHERE A 3 ASPHERE 2.665 1.492 57.4 4 ASPHERE 1.000 DIAPHRAGM ASPHERIC EQUATION: ##STR6## SURF. 2 C = 0.0753239 D = 0.2664E-04 F = 0.0 K = 0.0 E = -0.1178E-06 SURF. 3 C = 0.2053810 D = 0.3106E-03 F = 0.0 K = 0.0 E = 0.7509E-04 SURF. 4 C = 0.1434720 D = 0.1902E-02 F = -0.5487E-04 K = -1.505 E = 0.5799E-03 ZOOM FOCAL BACK FRONT SPACING LENS STOP RELATIVE LENGTH FOCUS FOCUS (A) LENGTH DIAMETER APERTURE __________________________________________________________________________ 49.91 48.15 43.84 5.407 10.072 3.50 13.48 41.79 43.40 29.99 8.939 13.604 3.50 12.13 35.06 39.45 18.50 13.108 17.773 3.50 11.00 __________________________________________________________________________

Claim 18

The zoom camera lens according to claim 1 and constructed according to the following chart, wherein the surfaces are numbered from an object side to an image side, all distances are in millimeters, V is the abbe number, index is the index of refraction, and both V and the index are for the e line of the spectrum: __________________________________________________________________________ SURFACE RADIUS THICKNESS INDEX V __________________________________________________________________________ DIAPHRAGM 7.223 1 -123.036 3.000 1.492 57.4 2 -12.6441 A 3 -18.1159 2.000 1.590 30.9 4 ASPHERE ASPHERIC EQUATION: ##STR7## C = -0.0118146 K = -34.6785420 VERTEX RADIUS = -84.6409 ZOOM FOCAL BACK FRONT SPACING LENS STOP RELATIVE LENGTH FOCUS FOCUS (A) LENGTH DIAMETER APERTURE __________________________________________________________________________ 34.98 7.67 51.32 21.357 26.357 3.18 11.00 42.02 17.42 56.41 16.050 21.050 3.18 13.22 49.97 28.42 62.14 11.859 16.859 3.18 15.71 __________________________________________________________________________

Claim 19

The zoom camera lens according to claim 1 and constructed according to the following chart, wherein the surfaces are numbered from an object side to an image side, all distances are in millimeters, V is the abbe number, index is the index of refraction, and both V and the index are for the e line of the spectrum: __________________________________________________________________________ SURFACE RADIUS THICKNESS INDEX V __________________________________________________________________________ 1 ASPHERE 3.300 1.492 57.4 2 ASPHERE A 3 ASPHERE 2.000 1.492 57.4 4 -100.678 ASPHERIC EQUATION: ##STR8## SURF. 1 C = -0.0965714 D = -0.6108431E-02 F = -0.1124789E-03 K = -46.9292770 E = 0.8978951E-03 VERTEX RADIUS = -10.3550 SURF. 2 C = -0.1479946 D = -0.3201587E-03 F = 0.0000000E+00 K = 0.0000000 E = -0.1153188E-04 VERTEX RADIUS = -6.7570 SURF. 3 C = -0.0446193 D = -0.2055898E-04 F = 0.0000000E+00 K = 0.0000000 E = -0.5733013E-07 VERTEX RADIUS = -22.4118 ZOOM FOCAL BACK FRONT SPACING LENS STOP RELATIVE LENGTH FOCUS FOCUS (A) LENGTH DIAMETER APERTURE __________________________________________________________________________ 35.00 7.57 43.31 25.751 31.051 3.18 11.00 42.65 22.49 47.23 16.628 21.928 3.18 13.40 49.97 36.74 50.99 10.522 15.822 3.18 15.70 __________________________________________________________________________