Variable-magnifying-power symmetrical lens system

Claim 2

A variable-magnifying-power lens system between stationary object and image planes and whose magnification may be continuously varied within a range near unity magnification comprising a plurality of lens elements arranged symmetrically with respect to a central stop in such a manner that at least one of the outermost lens elements on each side of the central stop may be shifted while maintaining the symmetry of all lens elements with respect to said central stop, and in which the lens system may be shifted as a unit to compensate for changes in focal lengths brought about by shifting of said lens elements.

Claim 3

A lens system according to claim 1, in which the outermost lens elements may be shifted.

Claim 4

A lens system according to claim 1, in which the next-to-the-outermost lens elements may be shifted.

Claim 5

A lens system according to claim 1, in which the outermost and the next-to-the-outermost lens elements may be shifted.

Claim 6

A variable-magnifying-power lens system according to claim 1, in which the focal length of each of the two outermost lens elements of the system are between about two and five times the compound focal length of the lens system.

Claim 7

A lens system according to claim 5, in which said two outermost lens elements are meniscus lenses whose concave surfaces are directed toward said central stop.

Claim 8

A lens system according to claim 6, in which there are ten lens elements in said system which are numbered consecutively from front to rear, those of the lens elements having concave surfaces are positioned so that such surfaces are directed toward the central stop.

Claim 9

A variable-magnifying-power lens system whose magnification may be continuously varied within a range near the unity magnification comprising 10 lens elements arranged symmetrical with respect to a center stop and numbered consecutively from front to rear, the first and tenth lenses being the positive meniscus lenses which are shifted toward and away from said center stop while maintaining said symmetry with respect to said center stop, the second and ninth lenses being the negative meniscus lenses, the third and fourth lenses and the seventh and eighth lenses being biconvex and biconcave lenses respectively cemented together, the fifth and sixth lenses being the positive meniscus lenses, the concave surfaces of all of said lenses and cemented lenses being directed toward to said center stop, the individual lenses having the following radii of curvature of the surfaces, the thicknesses and distance along the optical axis of lenses and air spaces, the indexes of refraction and Abbe numbers when d-line of helium is used with the maximum aperture ratio of 1 : 8, the focal between 240 mm and 258 mm and the magnification range between 0.7 and 1.4; r1 78.65 d1 6.58 N1 32 1.53996 V1 59.7 r2 101.29 d2 4.8- 21.4 r3 96.68 d3 3.29 N2 1.53172 V2 48.9 r4 64.89 d4 1.48 r5 56.40 d5 12.77 N3 1.67790 V3 55.5 r6 - 150.04 D6 2.38 N4 1.62374 V4 47.0 r7 44.58 D7 4.19 r8 59.50 d8 10.43 N5 1.58900 V5 48.6 r9 95.76 d9 8.43 r10 - 95.76 d10 10.43 N6 1.58900 V6 48.6 r11 - 59.50 d11 4.19 r12 - 44.58 d12 2.38 N7 1.62374 V7 47.0 r13 150.04 d13 12.77 N8 1.67790 V8 55.5 r14 - 56.40 d14 1.48 r15 - 64.89 d15 3.29 N9 1.53172 V9 48.9 r16 -96.68 d16 4.8-21.4 r17 - 101.19 d17 6.58 N10 1.53996 V10 59.7 r10 - 78.65 where x with a numerical subscript indicates the radius of curvature of a surface identified by the subscript, numbering the surfaces consecutively from front to rear, a plus radius indicates a surface convex toward the front while a minus radius indicates a surface concave toward the front, d with a numerical subscript indicates the thickness of the individual lens and the air space between the adjacent lenses numbering from front to rear, N with a subscript indicates the index of refraction of the lens identified by the subscript and V with a subscript indicates the Abbe number of the lens identified by The subscript.

Claim 10

A variable-magnifying-power lens system whose magnification may be continuously varied within a range near the unity magnification comprising 10 lens elements arranged symmetrical with respect to a center stop and numbered consecutively from front to rear, the first and tenth lenses being the positive meniscus lenses which are shifted toward and away from said center stop while maintaining said symmetry with respect to said center stop, the second and ninth lenses being the negative meniscus lenses, the third and fourth lenses and the seventh and eighth lenses being biconvex and biconcave lenses respectively cemented together, the fifth and sixth lenses being the positive meniscus lenses, the concave surfaces of all of said lenses and cemented lenses being directed toward to said center stop, the individual lenses having the following radii of curvature of the surfaces, the thicknesses and distance along the optical axis of lenses and air spaces, the indexes of refraction and Abbe numbers when d-line of helium is used with the maximum aperture ratio of 1 : 8, the focal between 240 mm and 258 mm and the magnification range between 0.7 and 1.4; r1 78.65 d1 6.58 N1 32 1.53996 V1 59.7 r2 101.29 d2 4.8- 21.4 r3 96.68 d3 3.29 N2 1.53172 V2 48.9 r4 64.89 d4 1.48 r5 56.40 d5 12.77 N3 1.67790 V3 55.5 r6 - 150.04 D6 2.38 N4 1.62374 V4 47.0 r7 44.58 D7 4.19 r8 59.50 d8 10.43 N5 1.58900 V5 48.6 r9 95.76 d9 8.43 r10 - 95.76 d10 10.43 N6 1.58900 V6 48.6 r11 - 59.50 d11 4.19 r12 - 44.58 d12 2.38 N7 1.62374 V7 47.0 r13 150.04 d13 12.77 N8 1.67790 V8 55.5 r14 - 56.40 d14 1.48 r15 - 64.89 d15 3.29 N9 1.53172 V9 48.9 r16 -96.68 d16 4.8-21.4 r17 - 101.19 d17 6.58 N10 1.53996 V10 59.7 r10 - 78.65 where x with a numerical subscript indicates the radius of curvature of a surface identified by the subscript, numbering the surfaces consecutively from front to rear, a plus radius indicates a surface convex toward the front while a minus radius indicates a surface concave toward the front, d with a numerical subscript indicates the thickness of the individual lens and the air space between the adjacent lenses numbering from front to rear, N with a subscript indicates the index of refraction of the lens identified by the subscript and V with a subscript indicates the Abbe number of the lens identified by The subscript.

Claim 11

A variable-magnifying-power lens system whose magnification may be continuously varied within a range near the unity magnification comprising 10 lens elements arranged symmetrical with respect to a center stop and numbered consecutively from front to rear, the first and tenth lenses being the positive meniscus lenses which are shifted toward and away from said center stop while maintaining said symmetry with respect to said center atop, the second and ninth lenses being the negative meniscus lenses, the third and fourth lenses and the seventh and eighth lenses being biconvex and biconcave lenses respectively cemented together, the fifth and sixth lenses being the positive meniscus lenses, the concave surfaces of all of said lenses and cemented lenses being directed toward to said center stop. the individual lenses having the following radii of curvature of the surfaces, the thicknesses and distance along the optical axis of lenses and air spaces, the indexes of refraction and Abbe numbers when d-line of helium is used with the maximum aperture ratio of 1 : 11, the focal length between 248 mm and 258 mm and the magnification range between 0.7 and 1.4; r1 - 67.1 d1 4.63 r2 75.254 d2 1.71-20.585 N1 1.54625 V1 59.7 r3 85.9 d3 3.45 r4 69.173 d4 2.41 N2 1.53993 V2 48.9 r5 53.785 d5 8.94 r6 - 144.61 d6 2.63 N3 1.68641 V3 55.5 r7 42.326 d6 2.90 N4 1.63306 V4 47.0 r8 59.235 d8 5.29 r9 88.855 d9 6.62 N5 1.61725 V5 46.2 r10 - 88.855 d10 5.29 V6 46.2 r11 -59.259 d11 2.90 N6 1.61725 r12 - 42.326 d12 2.63 V7 47.0 r13 144.61 d13 8.94 N7 1.63306 V8 55.5 r14 - 53.785 d14 2.41 N8 1.68641 r15 - 69.173 d15 3.45 V9 48.9 r16 -85.9 d16 1.71-20.585 N9 1.53933 r17 - 75.254 d17 4.36 V10 59.7 r18 - 67.1 N10 1.54625 where r with a numerical subscript indicates the radius of curvature of a surface identified by the subscript, numbering the surfaces consecutively from front to rear, a plus radius indicates a surface convex toward the front while a minus radius indicates a surface concave toward the front, d with a numerical subscript indicates the thickness of the individual lens and the air space between the adjacent lenses numbering from front to rear, N with a subscript indicates the index of refraction of the lens identified by the subscript and V with a subscript indicates the Abbe number of the lens identified by the subscript.

Claim 12

A variable-magnifying-power lens system whose magnification may be continuously varied within a range near the unity magnification comprising 10 lens elements arranged symmetrical with respect to a center stop and numbered consecutively from front to rear, the first and tenth lenses being the positive meniscus lenses which are shifted toward and away from said center stop while maintaining said symmetry with respect to said center atop, the second and ninth lenses being the negative meniscus lenses, the third and fourth lenses and the seventh and eighth lenses being biconvex and biconcave lenses respectively cemented together, the fifth and sixth lenses being the positive meniscus lenses, the concave surfaces of all of said lenses and cemented lenses being directed toward to said center stop. the individual lenses having the following radii of curvature of the surfaces, the thicknesses and distance along the optical axis of lenses and air spaces, the indexes of refraction and Abbe numbers when d-line of helium is used with the maximum aperture ratio of 1 : 11, the focal length between 248 mm and 258 mm and the magnification range between 0.7 and 1.4; r1 - 67.1 d1 4.63 r2 75.254 d2 1.71-20.585 N1 1.54625 V1 59.7 r3 85.9 d3 3.45 r4 69.173 d4 2.41 N2 1.53993 V2 48.9 r5 53.785 d5 8.94 r6 - 144.61 d6 2.63 N3 1.68641 V3 55.5 r7 42.326 d6 2.90 N4 1.63306 V4 47.0 r8 59.235 d8 5.29 r9 88.855 d9 6.62 N5 1.61725 V5 46.2 r10 - 88.855 d10 5.29 V6 46.2 r11 -59.259 d11 2.90 N6 1.61725 r12 - 42.326 d12 2.63 V7 47.0 r13 144.61 d13 8.94 N7 1.63306 V8 55.5 r14 - 53.785 d14 2.41 N8 1.68641 r15 - 69.173 d15 3.45 V9 48.9 r16 -85.9 d16 1.71-20.585 N9 1.53933 r17 - 75.254 d17 4.36 V10 59.7 r18 - 67.1 N10 1.54625 where r with a numerical subscript indicates the radius of curvature of a surface identified by the subscript, numbering the surfaces consecutively from front to rear, a plus radius indicates a surface convex toward the front while a minus radius indicates a surface concave toward the front, d with a numerical subscript indicates the thickness of the individual lens and the air space between the adjacent lenses numbering from front to rear, N with a subscript indicates the index of refraction of the lens identified by the subscript and V with a subscript indicates the Abbe number of the lens identified by the subscript.