Varifocal lens systems

Claim 2

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prime optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < infinity ... (2) 0 < OR = (1/rB3) (1/rB4) < (0.4/ fB ) ...(3) 0.5 fB < (rB5 + rB6 /2) < 2.0 fB ... (4) 0.08 < nB2-nB1 ... (5) 20 < Nu B1- Nu B2 ...(6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thicknesses of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e.

Claim 3

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prime optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) -(1/rB4) < (0.4/ fB ) ... (3) 0.5 fB < (rB5 + rB6 /2) < 2.0 fB ... (4) 0.08 < nB2-nB1 ... (5) 20 < Nu B1- Nu B2 ... (6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thickness of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e.

Claim 4

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prime optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) -(1/rB4) < (0.4/ fB ) ... (3) 0.5 fB < (rB5 + rB6 /2) < 2.0 fB ... (4) 0.08 < nB2-nB1 ... (5) 20 < Nu B1- Nu B2 ... (6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thickness of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e.

Claim 5

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prime optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) -(1/rB4) < (0.4/ fB ) ... (3) 0.5 fB < (rB5 + rB6 /2) < 2.0 fB ... (4) 0.08 < nB2-nB1 ... (5) 20 < Nu B1- Nu B2... (6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thicknesses of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e. f 76.5mm-153mm, F/4 rA1 78.828 dA1 4.09 rA2 441.679 dA2 0.19 fA 100.023 rA3 74.639 dA3 1.9 rA4 44.11 dA4 5.8 rA5 1,742.45 2.086-26.433 rB1 -175.362 dB1 1.7 rB2 133.175 dB2 2.96 rB3 -80.74 dB3 0.38 fB -34.432 rB4 -214.635 dB4 1.43 rB5 39.98 dB5 5.26 rB6 -35.068 dB6b 1.43 rB7 626.88 25.371-1.024 rC1 84.07 dC1 1.13 fC 88.145 rC2 36.191 dC2 3.95 rC3 -105.44 6.707-6.707 rD1 24.398 LDf dD1 4.74 rD2 Infinity dD2 0.29 rD3 23.802 dD3 6.13 rD4 -58.134 LDm dD4 0.21 fD 95.3 rD5 -56.853 dD5 2.1 rD6 16.931 dD6 28.38 rD7 57.497 dD7 7.0 rD8 -30.905 LDB dD8 1.48 rD9 -29.94 dD9 1.43 rD10 637.361 nA1 1.51633 Nu A1 64.15 LA nA2 1.74077 Nu A2 27.79 nA3 1.51821 Nu A3 65.04 nB1 1.618 Nu B1 63.38 nB2 1.7847 Nu B2 26.22 LBnB3 1.5725 Nu B3 57.65 nB4 1.618 Nu B4 63.38 nC1 1.74077 Nu C1 27.79 LCnC2 1.6223 Nu C2 53.2 nD1 1.51009 Nu D1 63.63 nD2 1.50048 Nu D2 65.99 LD nD3 1.744 Nu D3 44.78 nD4 1.60342 Nu D4 38.01 nD5 1.66998 Nu D5 39.32

Claim 6

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prime optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) -(1/rB4) < (0.4/ fB ) ... (3) 0.5 fB < (rB5 + rB6 /2) < 2.0 fB ... (4) 0.08 < nB2-nB1 ... (5) 20 < Nu B1- Nu B2... (6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thicknesses of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e. f 76.5mm-153mm, F/4 rA1 78.828 dA1 4.09 rA2 441.679 dA2 0.19 fA 100.023 rA3 74.639 dA3 1.9 rA4 44.11 dA4 5.8 rA5 1,742.45 2.086-26.433 rB1 -175.362 dB1 1.7 rB2 133.175 dB2 2.96 rB3 -80.74 dB3 0.38 fB -34.432 rB4 -214.635 dB4 1.43 rB5 39.98 dB5 5.26 rB6 -35.068 dB6b 1.43 rB7 626.88 25.371-1.024 rC1 84.07 dC1 1.13 fC 88.145 rC2 36.191 dC2 3.95 rC3 -105.44 6.707-6.707 rD1 24.398 LDf dD1 4.74 rD2 Infinity dD2 0.29 rD3 23.802 dD3 6.13 rD4 -58.134 LDm dD4 0.21 fD 95.3 rD5 -56.853 dD5 2.1 rD6 16.931 dD6 28.38 rD7 57.497 dD7 7.0 rD8 -30.905 LDB dD8 1.48 rD9 -29.94 dD9 1.43 rD10 637.361 nA1 1.51633 Nu A1 64.15 LA nA2 1.74077 Nu A2 27.79 nA3 1.51821 Nu A3 65.04 nB1 1.618 Nu B1 63.38 nB2 1.7847 Nu B2 26.22 LBnB3 1.5725 Nu B3 57.65 nB4 1.618 Nu B4 63.38 nC1 1.74077 Nu C1 27.79 LCnC2 1.6223 Nu C2 53.2 nD1 1.51009 Nu D1 63.63 nD2 1.50048 Nu D2 65.99 LD nD3 1.744 Nu D3 44.78 nD4 1.60342 Nu D4 38.01 nD5 1.66998 Nu D5 39.32

Claim 7

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prIme optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) - (1/rB4) < (0.4/ fB ) ...(3) 0.5 fB < (rB5 + rB6 /2) < 2.0 rB ...(4) 0.08 < nB2-nB1 ...(5) 20 < Nu B1- Nu B2 ...(6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thicknesses of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e. 0 < or = r 76.5mm-153mm, F/4 rA1 78.828 dA1 4.09 ... (rA2 441.679 dA2 0.19 fA 100.023 rB6 / dA3 1.9 fr... ( 44.11 dA4 5.8 rA5... (1,742.45 2.086-26.433 rB1 -175.362 ... (dB1 1.7 rB2 133.175 dB2 2.96 rB3 -80.74 dB3 0.38 fB -34.432 rB4 -214.635 dB4 1.43 rB5 39.98 dB5 5.26 rB6 -35.068 dB6 1.43 rB7 626.88 25.371-1.024 rC1 84.07 dC1 1.13 fC 88.145 rC2 36.191 dC2 3.95 rC3 -105.44 6.707-6.707 rD1 25.913 dD1 3.3 rD2 108.255 dD2 0.15 LDf rD3 46.923 dD3 2.5 rD4 98.549 dD4 0.2 rD5 24.83 dD5 5.74 fD 95.369LDM rD6 -115.109 dD6 2.0 rD7 16.95 dD7 26.0 rD8 51.876 dD8 7.0 rD9 -28.103 LDB dD9 1.44 rD10 -26.962 dD10 1.43 rD11 248.554 nA1 1.51633 Nu A1 64.15 LA nA2 1.74077 Nu A2 27.79 nA3 1.51821 Nu A3 65.04 nB1 1.618 Nu B1 63.38 nB2 1.7847 Nu B2 26.22 LBnB3 1.5725 Nu B3 57.65 nB4 1.618 Nu B4 63.38 nC1 1.74077 Nu C1 27.79 LCnC2 1.6223 Nu C2 53.2 nD1 1.50378 Nu D1 66.81 nD2 1.50048 Nu D2 65.99 nD3 1.50378 Nu D3 66.81 LDnD4 1.744 Nu D4 44.78 nD5 1.60717 Nu D5 40.34 nD6 1.66755 Nu D6 41.93

Claim 8

In a varifocal lens system comprising a varifocal optical system and a prime optical system, said varifocal optical system consisting of a first group of lenses having a positive refractive power, second group of lenses having a negative refractive power and third group of lenses having a positive refractive power, said prIme optical system consisting of a fourth group of lenses having a positive refractive power, and the change in position of the final image produced by the movement in a direction of the optical axis of said second group of lenses being adapted to be corrected by the reciprocal movement of said third group of lenses, the improvement wherein the said second group of lenses is constructed as 3 components and 4 lenses and consists of a first biconcave negative lens, second biconvex positive lens, third negative lens and fourth negative lens and in which said first and second lenses are combined together to form a composite lens having a positive refractive power and said third lens has its image side a deep concave surface and said fourth lens has its object side a deep concave surface, said third and fourth lenses being arranged such that their deep concave surfaces stand opposite each other with an air space therebetween, and said second group of lenses being defined by the following six conditions; i.e. rB1 < 0 ... (1) 2.0 fB < rB1 < Infinity ... (2) 0 < or = (1/rB3) - (1/rB4) < (0.4/ fB ) ...(3) 0.5 fB < (rB5 + rB6 /2) < 2.0 rB ...(4) 0.08 < nB2-nB1 ...(5) 20 < Nu B1- Nu B2 ...(6) where rBi (i 1, 2, ...) are radii of curvatures of the surfaces of the successive lenses from the front surface of the first lens and inclusive of the surface in contact between the first and second lenses, nBi (i 1, 2, ...) are axial center thicknesses of or air spaces between the successive lenses, Nu Bi (i 1, 2, ...) are Abbe''s numbers of the successive lenses, and fB is a composite focal length of the second group of lenses, and wherein the system is defined by the following values, i.e. 0 < or = r 76.5mm-153mm, F/4 rA1 78.828 dA1 4.09 ... (rA2 441.679 dA2 0.19 fA 100.023 rB6 / dA3 1.9 fr... ( 44.11 dA4 5.8 rA5... (1,742.45 2.086-26.433 rB1 -175.362 ... (dB1 1.7 rB2 133.175 dB2 2.96 rB3 -80.74 dB3 0.38 fB -34.432 rB4 -214.635 dB4 1.43 rB5 39.98 dB5 5.26 rB6 -35.068 dB6 1.43 rB7 626.88 25.371-1.024 rC1 84.07 dC1 1.13 fC 88.145 rC2 36.191 dC2 3.95 rC3 -105.44 6.707-6.707 rD1 25.913 dD1 3.3 rD2 108.255 dD2 0.15 LDf rD3 46.923 dD3 2.5 rD4 98.549 dD4 0.2 rD5 24.83 dD5 5.74 fD 95.369LDM rD6 -115.109 dD6 2.0 rD7 16.95 dD7 26.0 rD8 51.876 dD8 7.0 rD9 -28.103 LDB dD9 1.44 rD10 -26.962 dD10 1.43 rD11 248.554 nA1 1.51633 Nu A1 64.15 LA nA2 1.74077 Nu A2 27.79 nA3 1.51821 Nu A3 65.04 nB1 1.618 Nu B1 63.38 nB2 1.7847 Nu B2 26.22 LBnB3 1.5725 Nu B3 57.65 nB4 1.618 Nu B4 63.38 nC1 1.74077 Nu C1 27.79 LCnC2 1.6223 Nu C2 53.2 nD1 1.50378 Nu D1 66.81 nD2 1.50048 Nu D2 65.99 nD3 1.50378 Nu D3 66.81 LDnD4 1.744 Nu D4 44.78 nD5 1.60717 Nu D5 40.34 nD6 1.66755 Nu D6 41.93