Focusing means for a zoom lens group

Claim 2

A focusing mechanism for a zoom lens comprising a focusing lens group for focusing on an object, said focusing lens group comprising at least one focusing lens positioned behind a front lens group, said front lens group being positioned nearest to said object; a zooming lens group for zooming said object, a focusing ring having a focusing cam groove, said cam groove having a shape defined by curve D T , curve D T being defined by determining individual curves representing a necessary amount of corrective movement to be imparted upon said focusing lens group to prevent a focal surface from deviating with respect to a distance of each object being focused upon during zooming, and origin-moving and superposing said individual curves, said focusing cam groove moving said focusing lens group in relation to the portion of said D T curve corresponding to the distance of an object being focused upon and, a zoom ring having at least two cam grooves, said zoom ring being adapted to adjust a position of said focusing lens by a link mechanism which transfers movement of said zoom ring to said focusing ring during zooming.

Claim 3

A focusing mechanism according to claim 1, wherein an operating amount of the focusing ring is converted by a cam groove indicative of value g which determines the relationship between said operating amount and a varying amount of the focal length of a lens system, and the movement amount of said zoom ring by said focusing cam is determined in accordance with said converted value.

Claim 4

A focusing mechanism according to claim 1, wherein said zoom ring is composed of at least two portions, one zoom ring having a cam groove for the lens group moved for zooming, the other zoom ring having a zooming cam groove for the lens group moved for focusing, said both zoom rings being rotated integrally at the time of zooming whereas they may be moved independently of each other in the direction of the optical axis.

Claim 7

The method of claim 4 wherein degree of accuracy in approximation of said moving amount along curve D T is enhanced by adjusting the rate of zooming.

Claim 8

The method of claim 5 wherein at least one lens of a first focusing lens group nearest to an object being focused, and a second focusing lens group adjacent to said first focusing lens group, is moved to focus said zoom lens.

Claim 9

The method of claim 5 further comprising (a) enabling said focusing lens to be moved along the following exponential curve; and S=R(2 log R.sup.f f-log R.sup.u) wherein R is adequate positive real number U is object distance f f is focal length of the focusing lens group S is movement amount of each focusing lens (b) utilizing a part of said exponential curve S corresponding to a specific distance to an object to be focused to carry out the movement of said focusing lens in association with zooming.

Claim 10

A method of focusing a zoom lens as set forth in claim 4 characterized in that both said lens group nearest to an object to be focused and said second lens group adjacent to the afore-mentioned lens group as a whole are moved as a focusing lens.-

Claim 13

A zoom lens system having the numerical data given in Table 1 below and a movement amount curve D T given in Table 2 below, and in which said lens system comprises two lens groups of which the first lens group includes four lenses and the second group includes five lenses: TABLE 1 ______________________________________ Lens data (a) When R: Radius of curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number (b) Surface No. R D nd ν ______________________________________ 1 172.036 3.50 1.62004 36.3 2 ∞ 0.10 3 (c) First 82.224 1.70 1.77250 49.6 4 lens group 23.297 7.60 5 -373.238 1.50 1.77250 49.6 6 69.199 5.50 7 41.501 4.00 1.62004 36.3 8 251.042 (e) Variable 9 100.564 1.69680 55.5 10 -292.325 2.60 11 39.613 0.10 1.56883 61.1 12 149.413 4.00 13 (d) Second 22.672 0.10 1.51633 64.1 14 lens group 96.429 5.50 15 -341.320 5.50 1.80518 25.4 16 19.037 1.60 17 85.004 5.00 1.62004 36.3 18 -38.022 4.50 ______________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by integrally moving the eighth and ninth lens components Focal length Value of g U = 0.8 m U = 1 m U = 1.2 m U = 1.5 m U = 2 m U = 3 m U = 5 m U = 10 __________________________________________________________________________ m 69.140 0 -1.566 -1.205 -0.980 -0.765 -0.560 -0.365 -0.215 -0.106 63.608 11.515 -1.404 -1.082 -0.881 -0.688 -0.505 -0.329 -0.194 -0.096 58.896 22.424 -1.268 -0.978 -0.797 -0.623 -0.457 -0.298 -0.176 -0.087 54.833 32.727 -1.151 -0.889 -0.725 -0.567 -0.416 -0.272 -0.160 -0.079 51.296 42.424 -1.051 -0.813 -0.662 -0.519 -0.381 -0.249 -0.147 -0.073 48.186 51.515 -0.964 -0.746 -0.608 -0.476 -0.350 -0.229 -0.135 -0.067 45.433 60.606 -0.888 -0.687 -0.561 -0.439 -0.323 -0.211 -0.124 -0.062 42.977 69.091 -0.821 -0.636 -0.519 -0.406 -0.299 -0.195 -0.115 -0.057 40.773 76.970 -0.762 -0.590 -0.481 -0.377 -0.277 -0.181 -0.107 -0.053 38.784 84.242 -0.709 -0.549 -0.448 -0.351 -0.258 -0.169 -0.100 -0.049 36.980 91.515 -0.662 -0.513 -0.418 -0.328 -0.241 -0.157 -0.093 -0.046 35.336 100 -0.620 -0.480 -0.391 -0.307 -0.225 -0.147 -0.087 -0.043 __________________________________________________________________________ (p) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of negative value shows a movement toward the image side.

Claim 14

A zoom lens system having the numerical data given in Table 1 below and a movement amount curve D T given in Table 2 below, and in which said lens system comprises two lens groups of which the first lens group includes four lenses and the second group includes five lenses: TABLE 1 ______________________________________ Lens data (a) When R: Radius of curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number (b) Surface No. R D nd ν ______________________________________ 1 172.036 3.50 1.62004 36.3 2 ∞ 0.10 3 (c) First 82.224 1.70 1.77250 49.6 4 lens group 23.297 7.60 5 -373.238 1.50 1.77250 49.6 6 69.199 5.50 7 41.501 4.00 1.62004 36.3 8 251.042 (e) Variable 9 100.564 1.69680 55.5 10 -292.325 2.60 11 39.613 0.10 1.56883 61.1 12 149.413 4.00 13 (d) Second 22.672 0.10 1.51633 64.1 14 lens group 96.429 5.50 15 -341.320 5.50 1.80518 25.4 16 19.037 1.60 17 85.004 5.00 1.62004 36.3 18 -38.022 4.50 ______________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by integrally moving the eighth and ninth lens components Focal length Value of g U = 0.8 m U = 1 m U = 1.2 m U = 1.5 m U = 2 m U = 3 m U = 5 m U = 10 __________________________________________________________________________ m 69.140 0 -1.566 -1.205 -0.980 -0.765 -0.560 -0.365 -0.215 -0.106 63.608 11.515 -1.404 -1.082 -0.881 -0.688 -0.505 -0.329 -0.194 -0.096 58.896 22.424 -1.268 -0.978 -0.797 -0.623 -0.457 -0.298 -0.176 -0.087 54.833 32.727 -1.151 -0.889 -0.725 -0.567 -0.416 -0.272 -0.160 -0.079 51.296 42.424 -1.051 -0.813 -0.662 -0.519 -0.381 -0.249 -0.147 -0.073 48.186 51.515 -0.964 -0.746 -0.608 -0.476 -0.350 -0.229 -0.135 -0.067 45.433 60.606 -0.888 -0.687 -0.561 -0.439 -0.323 -0.211 -0.124 -0.062 42.977 69.091 -0.821 -0.636 -0.519 -0.406 -0.299 -0.195 -0.115 -0.057 40.773 76.970 -0.762 -0.590 -0.481 -0.377 -0.277 -0.181 -0.107 -0.053 38.784 84.242 -0.709 -0.549 -0.448 -0.351 -0.258 -0.169 -0.100 -0.049 36.980 91.515 -0.662 -0.513 -0.418 -0.328 -0.241 -0.157 -0.093 -0.046 35.336 100 -0.620 -0.480 -0.391 -0.307 -0.225 -0.147 -0.087 -0.043 __________________________________________________________________________ (p) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of negative value shows a movement toward the image side.

Claim 15

A zoom lens system having the numerical data given in Table 1 below and movement amount curve D T given in Table 2 below: TABLE 1 ______________________________________ Lens data (a) When R: Radius of curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number (b) Surface No. R D nd ν ______________________________________ 1 172.036 3.50 1.62004 36.3 2 ∞ 0.10 3 (c) First 82.224 1.70 1.77250 49.6 4 lens group 23.297 7.60 5 -373.238 1.50 1.77250 49.6 6 69.199 5.50 7 41.501 4.00 1.62004 36.3 8 251.042 (e) Variable 9 100.564 1.69680 55.5 10 -292.325 2.60 11 39.613 0.10 1.56883 61.1 12 149.413 4.00 13 (d) Second 22.672 0.10 1.51633 64.1 14 lens group 96.429 5.50 15 -341.320 5.50 1.80518 25.4 16 19.037 1.60 17 85.004 5.00 1.62004 36.3 18 -38.022 4.50 ______________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by moving the lens system as a whole Focal length Value of g U = 0.8 m U = 1 m U = 1.2 m U = 1.5 m U = 2 m U = 3 m U = 5 m U = 10 __________________________________________________________________________ m 69.140 0 7.543 5.721 4.611 3.573 2.600 1.683 0.988 0.486 63.608 12.105 6.288 4.789 3.869 3.004 2.190 1.420 0.834 0.411 58.896 23.684 5.327 4.070 3.294 2.562 1.870 1.215 0.714 0.352 54.833 34.211 4.575 3.503 2.839 2.211 1.616 1.051 0.619 0.305 51.296 44.211 3.974 3.049 2.474 1.929 1.411 0.918 0.541 0.267 48.186 53.684 3.486 2.679 2.175 1.698 1.243 0.809 0.477 0.235 45.433 63.158 3.085 2.373 1.929 1.506 1.103 0.719 0.424 0.209 42.977 71.579 2.751 2.118 1.722 1.345 0.986 0.643 0.379 0.187 40.793 80.000 2.469 1.902 1.548 1.209 0.887 0.578 0.341 0.168 38.784 87.368 2.230 1.719 1.399 1.093 0.802 0.523 0.308 0.152 36.980 93.684 2.024 1.561 1.271 0.993 0.729 0.475 0.280 0.138 35.336 100 1.847 1.424 1.160 0.907 0.665 0.434 0.256 0.126 __________________________________________________________________________ (s) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of positive value show a movement toward the object side.

Claim 16

A zoom lens system having the numerical data given in Table 1 below and movement amount curve D T given in Table 2 below: TABLE 1 ______________________________________ Lens data (a) When R: Radius of curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number (b) Surface No. R D nd ν ______________________________________ 1 172.036 3.50 1.62004 36.3 2 ∞ 0.10 3 (c) First 82.224 1.70 1.77250 49.6 4 lens group 23.297 7.60 5 -373.238 1.50 1.77250 49.6 6 69.199 5.50 7 41.501 4.00 1.62004 36.3 8 251.042 (e) Variable 9 100.564 1.69680 55.5 10 -292.325 2.60 11 39.613 0.10 1.56883 61.1 12 149.413 4.00 13 (d) Second 22.672 0.10 1.51633 64.1 14 lens group 96.429 5.50 15 -341.320 5.50 1.80518 25.4 16 19.037 1.60 17 85.004 5.00 1.62004 36.3 18 -38.022 4.50 ______________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by moving the lens system as a whole Focal length Value of g U = 0.8 m U = 1 m U = 1.2 m U = 1.5 m U = 2 m U = 3 m U = 5 m U = 10 __________________________________________________________________________ m 69.140 0 7.543 5.721 4.611 3.573 2.600 1.683 0.988 0.486 63.608 12.105 6.288 4.789 3.869 3.004 2.190 1.420 0.834 0.411 58.896 23.684 5.327 4.070 3.294 2.562 1.870 1.215 0.714 0.352 54.833 34.211 4.575 3.503 2.839 2.211 1.616 1.051 0.619 0.305 51.296 44.211 3.974 3.049 2.474 1.929 1.411 0.918 0.541 0.267 48.186 53.684 3.486 2.679 2.175 1.698 1.243 0.809 0.477 0.235 45.433 63.158 3.085 2.373 1.929 1.506 1.103 0.719 0.424 0.209 42.977 71.579 2.751 2.118 1.722 1.345 0.986 0.643 0.379 0.187 40.793 80.000 2.469 1.902 1.548 1.209 0.887 0.578 0.341 0.168 38.784 87.368 2.230 1.719 1.399 1.093 0.802 0.523 0.308 0.152 36.980 93.684 2.024 1.561 1.271 0.993 0.729 0.475 0.280 0.138 35.336 100 1.847 1.424 1.160 0.907 0.665 0.434 0.256 0.126 __________________________________________________________________________ (s) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of positive value show a movement toward the object side.

Claim 17

A zoom lens system having the numerical data given in Table 1 below and movement amount curve D T given in Table 2 below: TABLE 1 __________________________________________________________________________ Lens data (a) When R: Radius curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number Surface No. R D nd ν __________________________________________________________________________ 1 154.085 2.00 1.80518 25.4 2 71.160 7.00 1.62299 58.2 3 First lens group -408.750 0.10 4 50.885 4.50 1.62299 58.2 5 82.750 Variable 6 133.870 1.20 1.77250 49.6 7 17.125 6.44 8 -119.741 2.50 1.80518 25.4 9 Second lens group -37.040 1.00 1.77250 49.6 10 73.977 0.10 11 27.602 2.20 1.80518 25.4 12 39.973 Variable 13 65.439 4.75 1.58913 61.1 14 -20.400 1.00 1.80518 25.4 15 Third lens group -29.765 1.10 16 21.416 3.46 1.51633 64.1 17 65.918 Variable 18 119.573 3.76 1.71736 29.5 19 -17.128 1.00 1.77250 49.6 20 Fourth lens group 41.633 1.49 21 -34.680 1.00 1.77250 49.6 22 140.021 Variable 23 -129.801 4.95 1.71300 53.9 24 -16.485 1.00 1.80518 25.4 25 -27.188 0.30 26 -97.088 1.00 1.80610 40.9 27 Fifth lens group 24.597 7.50 1.58913 61.1 28 -45.921 0.30 29 42.314 4.16 1.51633 64.1 30 312.792 __________________________________________________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by moving the first and second lens groups Focal length Value of g U = 1.5 m U = 2 m U = 3 m U = 5 m U = 7 m U = 15 m __________________________________________________________________________ 131.863 0 2.863 2.163 1.454 0.878 0.629 0.295 104.916 22.326 2.038 1.526 1.016 0.609 0.435 0.203 90.899 34.884 1.670 1.245 0.825 0.493 0.351 0.164 79.898 44.186 1.426 1.060 0.700 0.417 0.297 0.138 70.786 53.953 1.247 0.924 0.609 0.362 0.258 0.120 62.973 61.395 1.105 0.818 0.538 0.320 0.227 0.106 55.982 68.837 0.984 0.727 0.478 0.284 0.202 0.093 49.338 76.279 0.898 0.648 0.425 0.252 0.179 0.083 42.840 83.721 0.781 0.575 0.377 0.223 0.159 0.073 36.326 91.163 0.691 0.508 0.333 0.197 0.140 0.065 28.969 100 0.598 0.439 0.287 0.170 0.120 0.056 __________________________________________________________________________ (r) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of positive value shows a movement toward the object side.

Claim 18

A zoom lens system having the numerical data given in Table 1 below and movement amount curve D T given in Table 2 below: TABLE 1 __________________________________________________________________________ Lens data (a) When R: Radius curvature D: Distance between lens surfaces n.sub.d : Refractive index for d-line ν: Abbe's number Surface No. R D nd ν __________________________________________________________________________ 1 154.085 2.00 1.80518 25.4 2 71.160 7.00 1.62299 58.2 3 First lens group -408.750 0.10 4 50.885 4.50 1.62299 58.2 5 82.750 Variable 6 133.870 1.20 1.77250 49.6 7 17.125 6.44 8 -119.741 2.50 1.80518 25.4 9 Second lens group -37.040 1.00 1.77250 49.6 10 73.977 0.10 11 27.602 2.20 1.80518 25.4 12 39.973 Variable 13 65.439 4.75 1.58913 61.1 14 -20.400 1.00 1.80518 25.4 15 Third lens group -29.765 1.10 16 21.416 3.46 1.51633 64.1 17 65.918 Variable 18 119.573 3.76 1.71736 29.5 19 -17.128 1.00 1.77250 49.6 20 Fourth lens group 41.633 1.49 21 -34.680 1.00 1.77250 49.6 22 140.021 Variable 23 -129.801 4.95 1.71300 53.9 24 -16.485 1.00 1.80518 25.4 25 -27.188 0.30 26 -97.088 1.00 1.80610 40.9 27 Fifth lens group 24.597 7.50 1.58913 61.1 28 -45.921 0.30 29 42.314 4.16 1.51633 64.1 30 312.792 __________________________________________________________________________ TABLE 2 __________________________________________________________________________ Movement amounts when focusing by moving the first and second lens groups Focal length Value of g U = 1.5 m U = 2 m U = 3 m U = 5 m U = 7 m U = 15 m __________________________________________________________________________ 131.863 0 2.863 2.163 1.454 0.878 0.629 0.295 104.916 22.326 2.038 1.526 1.016 0.609 0.435 0.203 90.899 34.884 1.670 1.245 0.825 0.493 0.351 0.164 79.898 44.186 1.426 1.060 0.700 0.417 0.297 0.138 70.786 53.953 1.247 0.924 0.609 0.362 0.258 0.120 62.973 61.395 1.105 0.818 0.538 0.320 0.227 0.106 55.982 68.837 0.984 0.727 0.478 0.284 0.202 0.093 49.338 76.279 0.898 0.648 0.425 0.252 0.179 0.083 42.840 83.721 0.781 0.575 0.377 0.223 0.159 0.073 36.326 91.163 0.691 0.508 0.333 0.197 0.140 0.065 28.969 100 0.598 0.439 0.287 0.170 0.120 0.056 __________________________________________________________________________ (r) In the table in the above, the value of g represents the position of the focal length located between the longest focal length selected as 0 and the shortest focal length selected as 100. A movement amount of positive value shows a movement toward the object side.