Zoom lens system

Claim 2

A zoom lens system comprising, in the order from the object side; a positive first lens group including a positive lens component comprising a negative and a positive lens cemented together, and a positive meniscus lens component convex to the object side; a negative second lens group including a negative lens component and a negative lens component comprising a negative lens and at least one positive lens cemented together; a positive third lens group including at least one positive lens component and a positive lens component comprising a positive and a negative lens cemented together; a negative fourth lens group including a negative lens component; and a positive fifth lens group comprising a forward and a rearward group spaced a substantial distance apart from each other by an air space, said forward group including a positive meniscus lens component convex to the object side, said forward group bearing almost all of the power of the fifth lens group, said rearward group including a negative meniscus lens component convex to the image side and a positive lens component, said first lens group being movable on the optical axis of the system to perform the focusing function, said second lens group being linearly movable on said optical axis and cooperable with said third lens group non-linearly movable simultaneously with, but in the opposite direction to, said second lens group to perform the magnification changing function of maintaining a predetermined image field position while converging the light flux over the entire magnification changing range, said fourth and said fifth lens groups being fixed for said magnification change and said focusing to thereby form a relay lens.

Claim 3

A zoom lens system according to claim 1, wherein said forward group in said fifth lens group further includes a negative lens.

Claim 4

A zoom lens system according to claim 1, wherein said second lens group includes a negative lens component and a negative lens component comprising a triplet consisting of a positive meniscus lens convex to the image side, a biconcave lens and a positive lens cemented together, and said third lens group includes two positive lens components and a positive lens component comprising a positive and a negative lens cemented together.

Claim 5

A zoom lens system according to claim 1, wherein the following conditions are satisfied: 2.9fW<f.sub.1 <3.7fW, 0.8fW<|f.sub.2 |<1.1fW, 1.0fW<f.sub.3 <1.4fW, 1.4fW<|f.sub.4 |<1.7fW, and 2.0fW<f.sub.5 <2.4fW, where f 1 , f 2 , f 3 , f 4 and f 5 represent the focal lengths of said first, second, third, fourth and fifth lens groups, respectively, and fW represents the shortest focal length of the entire lens system; wherein the zoom lens system is for use with 35 mm camera having an F-number of about 4.5 and a zoom ratio of about 6.0; wherein the following conditions are satisfied: 0.7f.sub.5 <f'.sub.5 <1.0f.sub.5 and 0.4f.sub.5 <D.sub.5, where f' 5 represents the focal length of the forward group in said fifth lens group, and D 5 the air space between the forward and the rearward group in said fifth lens group; wherein the following conditions are satisfied; ν.sub.1p -ν.sub.1n >34, N.sub.1p <1.55, N.sub.1n >1.70, -0.3<SF.sub.11 <0.0, -2.0<SF.sub.12 <-1.0, 0.5<SF.sub.21 <2.0, -1.6<SF.sub.22 <-0.5, ν.sub.2n -ν.sub.2p >23, N.sub.21 >1.7, -0.6<SF.sub.32 <0.0, ν.sub.3p -ν.sub.3n >43, N.sub.3p <1.55, N.sub.3n >1.75, -0.2<SF.sub.4 <0.2, N.sub.4 >1.7, -4.0<SF.sub.51 <-1.0, -6.0<SF.sub.52 <-2.0, N.sub.5p <1.57 and N.sub.5n >1.73, where ν and N represent the Abbe number and refractive index, respectively, of each lens component, SF represents the shape factor of each lens component, the first of the suffix numbers represents the lens group to which each lens component belongs, the second of the suffix numbers represents the order of each lens component in each lens group from the object side, n and p signify a negative lens and a positive lens, and the shape factor is defined as SF=(r F +r R )/(r F =r R ), where r F is the curvature radius of the surface of each lens component which faces the object side, and r R is the curvature radius of the surface of each lens which faces the image side; the zoom lens system having the following numerical data: ______________________________________ f = 50.000-297.267 F/4.5 zoom ratio = 5.945 Angle of view 48.6°-8.0° i r.sub.i d.sub.i N.sub.i υ.sub.i ______________________________________ 1 308.300 2.0 1.74950 35.0 2 111.000 12.0 1.50032 81.9 3 -388.141 0.2 4 106.700 8.0 1.52000 70.1 5 2072.540 d.sub.5 6 2900.000 2.0 1.71300 53.9 7 46.959 9.2 8 -65.200 2.0 1.62041 60.3 9 39.920 7.1 1.68893 31.1 10 -511.394 d.sub.10 11 415.900 5.1 1.52000 70.1 12 -83.802 0.2 13 68.500 10.2 1.52000 70.1 14 -48.650 2.0 1.80518 25.5 15 -97.436 d.sub.15 16 -123.500 2.0 1.71300 53.9 17 92.434 1.502 18 35.470 5.4 1.56138 45.3 19 88.858 58.5 20 -21.321 2.4 1.76684 46.6 21 -34.769 0.2 22 78.649 5.4 1.51823 59.0 23 -131.454 ______________________________________ f 50.000 122.505 297.267 d.sub.5 1.107 41.977 67.285 d.sub.10 104.031 48.890 2.247 d.sub.15 4.512 18.783 40.116 ______________________________________ f.sub.1 = 164.325 = 3.287 fW f.sub.2 = -45.376 = -0.908 fW f.sub.3 = 58.702 = 1.174 fW f.sub.4 = -73.861 = -1.477 fW f.sub.5 = 115.643 = 2.313 fW Full length = 285.122 Back focal distance = 40.071 Diaphragm disposed 2.0mm ahead of the 16th surface, ______________________________________ where r i represents the curvature radius of each lens, d i the center thickness of each lens of the air space between adjacent lenses, N i the refractive index of the glass of each lens for the d-line, and ν i the Abbe number of the glass of each lens.

Claim 6

A zoom lens system according to claim 1, wherein the following conditions are satisfied: 2.9fW<f.sub.1 <3.7fW, 0.8fW<|f.sub.2 |<1.1fW, 1.0fW<f.sub.3 <1.4fW, 1.4fW<|f.sub.4 |<1.7fW, and 2.0fW<f.sub.5 <2.4fW, where f 1 , f 2 , f 3 , f 4 and f 5 represent the focal lengths of said first, second, third, fourth and fifth lens groups, respectively, and fW represents the shortest focal length of the entire lens system; wherein the zoom lens system is for use with 35 mm camera having an F-number of about 4.5 and a zoom ratio of about 6.0; wherein the following conditions are satisfied: 0.7f.sub.5 <f'.sub.5 <1.0f.sub.5 and 0.4f.sub.5 <D.sub.5, where f' 5 represents the focal length of the forward group in said fifth lens group, and D 5 the air space between the forward and the rearward group in said fifth lens group; wherein the following conditions are satisfied; ν.sub.1p -ν.sub.1n >34, N.sub.1p <1.55, N.sub.1n >1.70, -0.3<SF.sub.11 <0.0, -2.0<SF.sub.12 <-1.0, 0.5<SF.sub.21 <2.0, -1.6<SF.sub.22 <-0.5, ν.sub.2n -ν.sub.2p >23, N.sub.21 >1.7, -0.6<SF.sub.32 <0.0, ν.sub.3p -ν.sub.3n >43, N.sub.3p <1.55, N.sub.3n >1.75, -0.2<SF.sub.4 <0.2, N.sub.4 >1.7, -4.0<SF.sub.51 <-1.0, -6.0<SF.sub.52 <-2.0, N.sub.5p <1.57 and N.sub.5n >1.73, where ν and N represent the Abbe number and refractive index, respectively, of each lens component, SF represents the shape factor of each lens component, the first of the suffix numbers represents the lens group to which each lens component belongs, the second of the suffix numbers represents the order of each lens component in each lens group from the object side, n and p signify a negative lens and a positive lens, and the shape factor is defined as SF=(r F +r R )/(r F -r R ), where r F is the curvature radius of the surface of each lens component which faces the object side, and r R is the curvature radius of the surface of each lens which faces the image side; the zoom lens system having the following numerical data: ______________________________________ f = 50.000-297.264 F/4.5 zoom ratio = 5.945 Angle of view 48.6°-8.0° i r.sub.i - d.sub.i N.sub.i υ.sub.i ______________________________________ 1 308.300 2.0 1.74950 35.0 2 111.000 12.0 1.50032 81.9 3 -388.141 0.2 4 106.700 8.0 1.52000 70.1 5 2072.540 d.sub.5 6 2900.000 2.0 1.71300 53.9 7 46.959 9.2 8 -65.200 2.0 1.62041 60.3 9 39.920 7.1 1.68893 31.1 10 -511.393 d.sub.10 11 415.900 5.1 1.52000 70.1 12 -83.802 0.2 13 68.500 10.2 1.52000 70.1 14 -48.650 2.0 1.80518 25.5 15 -97.436 d.sub.15 16 -132.000 2.0 1.69350 53.6 17 84.224 1.542 18 35.200 5.5 1.53256 46.0 19 401.093 1.0 20 941.600 2.0 1.74443 49.4 21 135.500 57.5 22 -21.470 2.5 1.76684 46.6 23 -35.094 0.2 24 70.000 5.5 1.51783 61.1 25 -137.617 ______________________________________ f 50.000 122.505 297.264 d.sub.5 1.107 41.977 67.286 d.sub.10 104.031 48.890 2.247 d.sub.15 4.459 16.729 38.063 ______________________________________ f.sub.1 = 164.325 = 3.287 fW f.sub.2 = -45.376 = -0.908 fW f.sub.3 = 58.702 = 1.174 fW f.sub.4 = -73.861 = -1.477 fW f.sub.5 = 115.643 = 2.313 fW Full length = 286.804 Back focal distance = 39.466 Diaphragm disposed 2.0mm ahead of the 16th surface, ______________________________________ where r i represents the curvature radius of each lens, d i the center thickness of each lens or the air space between adjacent lenses, N i the refractive index of the glass of each lens for the d-line and ν i the Abbe number of the glass of each lens.

Claim 7

A zoom lens system according to claim 1, wherein the following conditions are satisfied: 2.9fW<f.sub.1 <3.7fW, 0.8fW<|f.sub.2 |<1.1fW, 1.0fW<f.sub.3 <1.4fW, 1.4fW<|f.sub.4 |<1.7fW, and 2.0fW<f.sub.5 <2.4fW, where f 1 , f 2 , f 3 , f 4 and f 5 represent the focal lengths of said first, second, third, fourth and fifth lens groups, respectively, and fW represents the shortest focal length of the entire lens system; wherein the zoom lens system is for use with 35 mm camera having an F-number of about 4.5 and a zoom ratio of about 6.0; wherein the following conditions are satisfied: 0.7f.sub.5 <f'.sub.5 <1.0f.sub.5 and 0.4f.sub.5 <D.sub.5, where f' 5 represents the focal length of the forward group in said fifth lens group, and D 5 the air space between the forward and the rearward group in said fifth lens group; wherein the following conditions are satisfied; ν.sub.1p -ν.sub.1n >34, N.sub.1p <1.55, N.sub.1n >1.70, -0.3<SF.sub.11 <0.0, -2.0<SF.sub.12 <-1.0, 0.5<SF.sub.21 <2.0, -1.6<SF.sub.22 <-0.5, ν.sub.2n -ν.sub.2p >23, N.sub.21 >1.7, -0.6<SF.sub.32 <0.0, ν.sub.3p -ν.sub.3n >43, N.sub.3p <1.55, N.sub.3n >1.75, -0.2<SF.sub.4 <0.2, N.sub.4 >1.7, -4.0<SF.sub.51 <-1.0, -6.0<SF.sub.52 <-2.0, N.sub.5p <1.57 and N.sub.5n >1.73, where ν and N represent the Abbe number and refractive index, respectively, of each lens component, SF represents the shape factor of each lens component, the first of the suffix numbers represents the lens group to which each lens component belongs, the second of the suffix numbers represents the order of each lens component in each lens group from the object side, n and p signify a negative lens and a positive lens, and the shape factor is defined as SF=(r F +r R )/(r F -r R ), where r F is the curvature radius of the surface of each lens component which faces the object side, and r R is the curvature radius of the surface of each lens which faces the image side; the zoom lens system having the following numerical data: ______________________________________ f = 50.000-295.200 F/4.5 zoom ratio = 5.904 Angle of view 48.6°-8.06° i r.sub.i d.sub.i N.sub.i υ.sub.i ______________________________________ 1 308.300 2.0 1.74950 35.0 2 112.000 12.5 1.50032 81.9 3 -401.400 0.2 4 107.800 8.5 1.52000 70.1 5 2970.199 d.sub.5 6 3512.50 2.0 1.71300 53.9 7 48.500 9.6 8 -62.150 3.5 1.66998 39.2 9 -48.310 2.0 1.56384 60.8 10 63.040 5.1 1.80518 25.5 11 447.757 d.sub.11 12 139.600 5.2 1.52000 70.1 13 -109.444 0.2 14 109.000 4.5 1.52000 70.1 15 -208.886 0.2 16 158.100 6.3 1.52000 70.1 17 -70.590 2.0 1.80518 25.5 18 -393.102 d.sub.18 19 -116.300 2.0 1.71300 53.9 20 99.709 0.963 21 33.760 5.2 1.56732 42.8 22 82.393 54.7 23 -20.400 2.3 1.76684 46.6 24 -33.267 0.2 25 75.250 5.2 1.51823 59.0 26 -124.176 ______________________________________ f 50.000 122.458 295.200 d.sub.5 1.879 41.998 66.699 d.sub.11 102.313 47.342 0.629 d.sub.18 3.249 18.099 40.111 ______________________________________ f.sub.1 = 164.325 = 3.287 fW f.sub.2 = -45.963 = -0.919 fW f.sub.3 = 59.461 = 1.189 fW f.sub.4 = -75.004 = -1.500 fW f.sub.5 = 110.645 = 2.213 fW Full length = 281.535 Back focal distance = 39.732 Diaphragm disposed 2.0mm ahead of the 19th surface, ______________________________________ where r i represents the curvature radius of each lens, d i the center thickness of each lens or the air space between adjacent lenses, N i the refractive index of the glass of each lens for the d-line, and ν i the Abbe number of the glass of each lens.