JPH05264903A - Wide-angle zoom lens - Google Patents

Abstract

PURPOSE:To provide the zoom lens which has a wide angle and is bright, and can correct satisfactorily its aberration without enlarging the overall length and the outside diameter by constituting a first lens group of two groups of specific front and rear groups. CONSTITUTION:In the lens system which consists of a first lens group of positive refracting power, a second lens group of positive refracting power, and a third lens group of negative refracting power in order from an object side, and can execute variable power by varying an interval between a first lens group and a second lens group, and an interval between a second group and a third group, a first lens group is constituted of two groups of the front group and the rear group, so that the following condition is satisfied. That is, ¦phif/phi1¦<6.0, provided that phif and phi1 denote refracting power of the front group of a first lens group, and a first lens group, respectively. According to this constitution, the overall length of a lens system can be shortened, by forming a first lens group, a second lens group, and a third group zoom lens as a fundamental constitution, a first lens group can be formed to a lens constitution being suitable for converting to a wide-angle, and the wide-angle conversion can be attained moderately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-angle zoom lens.

[0002]

2. Description of the Related Art In recent years, a fully automatic camera equipped with a zoom lens having a high zoom ratio has been remarkably commercialized as a new concept camera. In this way, if the zoom lens has a high zoom ratio, it will surely be in the direction of widening the angle or telephoto.

A conventional zoom lens has a wide-angle end of 2ω = 6.
It is about 3 ° or 2ω = in the low zoom lens.
Those of about 84 ° are known. For example, Japanese Patent Laid-Open No. 2-2
The lens system is disclosed in Japanese Patent No. 84109.

Further, the lens system described in Japanese Patent Laid-Open No. 2-135312 makes it possible to adapt a super wide-angle zoom lens, which was conventionally known only as an interchangeable lens for single-lens reflex cameras, to a compact camera. It is a compact zoom lens.

[0005]

Each of the zoom lenses described above is an attempt to widen the angle of the conventional type as it is, and it is difficult to correct aberrations. That is, although the focal length is shortened, the zoom lens is a telephoto type, which is insufficient in terms of optical performance.

An object of the present invention is to provide a zoom lens which is based on a conventional zoom lens having a three-group structure and has a wide-angle, bright and well-corrected aberration by appropriately adjusting the structure of the first lens group. To provide.

[0007]

A zoom lens according to the present invention comprises a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power in order from the object side. A second lens group, and a distance between the first lens group and the second lens group and a second lens group.
A lens system that performs zooming by changing the distance between the lens group and the third lens group. The first lens group is composed of two groups, a front group and a rear group, and the following condition (1) is satisfied: It is characterized by being satisfied. (1) | φf / φ1 | <6.0 where φf and φ1 are the front group and the first group of the first lens group, respectively.
It is the refractive power of the lens group.

The present invention further develops the attempt to widen the angle of the lens system proposed by the present applicant in Japanese Patent Laid-Open No. 2-135312 to shorten the total length of the lens system, and also to reduce the total length of the lens system on the object side. In order from the first lens group having a positive refractive power, the second lens group having a positive refractive power, and the third lens group having a negative refractive power.
By using a three-group zoom lens composed of lens groups as a basic configuration and the first lens group as a lens configuration suitable for widening the angle, the widening of the angle can be achieved without difficulty.

The lens system of Japanese Patent Application No. 2-1521 proposed by the present applicant has a negative lens component and a positive lens component constituting this lens group without changing the configuration of the first lens group itself. By arranging them with a certain distance or more, the incident angle of the off-axis ray to the second lens group having a positive refractive power can be made small to facilitate aberration correction and achieve a wide angle. ..

On the other hand, according to the present invention, the structure itself of the first lens group is changed to one suitable for widening the angle based on the following idea.

The zoom lens of the present invention does not have a wide-angle lens system as a basic specification from the beginning, but is designed by setting an angle of view that is easy to design from the wide-angle end to the telephoto end. Is shifted to the wide-angle side to obtain a wide-angle zoom lens.

Specifically, for example, first, the focal length f is 3
28mm if you design an optical system of 5mm to 135mm and attach a 0.8x wide angle attachment to it.
A lens system of up to 105 mm can be obtained. If the basic lens system has a short overall length and a small lens outer diameter, even if an attachment for widening the angle is added to this, the overall lens system does not become so large.

If the wide-angle attachment is incorporated into a basic optical system to make one optical system as a whole, it is considered that the attachment is arranged as a lens group for aberration correction. That is, the above attachment is considered to be a lens component for widening the angle in the lens system, which has evolved from the property as an afocal converter.

In the present invention, as shown in FIG. 43, this lens component is the front lens group La of the first lens group, and the first lens group of the basic optical system is the rear lens group Lb of the first lens group as described above. It was composed. That is, the reverse telephoto type of the wide-angle lens is a lens system that starts with the first lens group of the wide-angle afocal converter (front group) and the positive lens group (rear group),
The lens system of the present invention is a retrofocus type lens system in which the actual distance between the two is reduced for compactness.

Here, in order to achieve the object of the present invention, it is necessary to satisfy the above condition (1). If this condition is not satisfied, it will be difficult to achieve the object of the present invention.

The present invention is configured as described above to obtain a wide-angle zoom lens having an angle of view 2ω at the wide-angle end of about 63 ° or more. That is, in the present invention, in order to make the lens system wide-angled, the zoom lens type and the lens structure were not changed. If the angle of view is widened without changing the type or configuration of the lens system in this way, the load on the third lens group becomes heavy, and it is not possible to ensure a sufficient back focus at the wide-angle end. In addition, the burden of magnification at the telephoto end becomes extremely large, which makes it difficult to correct aberrations, which makes it difficult to manufacture for correction.

In order to solve such a problem, an aspherical surface is used, or a graded index lens, especially a radial type graded index lens, which presently has a problem in terms of production technology is used. These are not easy lenses to make.

Generally, when widening the angle of a lens system, a problem occurs in aberration correction because the paths of the central light beam and the off-axis light beam greatly differ in the lens system. That is, as the angle of view increases, field curvature, distortion, lateral chromatic aberration, sagittal coma flare, and the like increase. Therefore, in order to satisfactorily correct the aberration, it is desirable to have a symmetrical type or a configuration close to this.

For the above reasons, in the present invention, as described above, the zoom lens based on the three-group zoom lens is used.
It is also characterized in that an aperture stop is arranged at the center of the lens group, and the lens system has a lens structure close to a symmetric type, which is an extremely preferable lens system for aberration correction. Also, with this lens system, the basic configuration does not change even if the diaphragm position is moved back and forth, only the usable range of the light flux changes.

Since it is preferable to make the lens structure symmetrical in terms of aberration correction, the components of the lens structure are taken into consideration so as to be suitable for widening the angle. In particular, in the lens type used in the present invention, the back focus can be shortened, the total length of the lens system can be shortened, and the outer diameter of the lens can be reduced. From this point of view, the present invention is based on a lens system which is symmetrical with respect to the diaphragm, and by adding a lens component to the lens system to widen the angle, it is possible to construct a more excellent wide-angle zoom lens.

Here, the front lens group of the first lens group complements the operation of the rear lens group. The zoom lens having the above-described configuration is the first
Considering the light flux passing through the lens group and the third lens group, these lens groups have a large influence on the off-axis aberration,
The lens group has a large influence mainly on axial aberrations such as spherical aberrations.

In order to further widen the angle of the lens system, it is necessary to correct specific aberrations such as lateral chromatic aberration and distortion having an inflection point. That is, it is necessary to pay attention to the configuration of the first lens group and the third lens group in order to correct the aberration peculiar to widening the angle in the configuration of the zoom lens of the present invention having the above-mentioned properties. .. Further, in order to increase the aperture ratio, it is necessary to pay attention to the configuration of the second lens group.

Considering the wide-angle end, it is not advisable to significantly increase the number of constituent lenses of the third lens group. Since the optical system of the present invention is an optical system in which the rear principal point position is located behind the lens system in a power arrangement, it is difficult to secure a back focus before aberration correction, and conversely, the degree of freedom of aberration correction is high. Less. Therefore, it is desirable that the third lens group be configured with a small number of lenses by using an aspherical surface. As a result, residual aberration can be suppressed by the third lens group itself, and higher-order aberrations that occur in the first lens group can be corrected and balanced as a whole. In addition, the back focus can be secured without difficulty, and the problem of the rear lens diameter increasing and the problem of flare due to internal reflection from the film surface can be reduced.

In consideration of the above points, it is preferable that the first lens group be devised to correct high-order lateral chromatic aberration, distortion, etc. peculiar to the wide-angle lens.

The off-axis ray height is particularly high near the wide-angle end, and it is difficult to correct residual high-order aberrations by the second lens unit and the third lens unit unless aberrations are corrected sufficiently in the first lens unit. is there. This can be seen by looking at the aberration correction coefficient. In particular, it is meaningful to see the balance between high-order aberrations and low-order aberrations.

Tables 1 and 2 show the correction situation in the first lens group by the aberration coefficient of Example 1 described later.

Table 1 Wide-angle end K SA3 CMA3 AST3 DIS3 PTZ3 1 -0.00001 -0.00060 -0.00634 -0.68756 -0.01525 Lf 2 0.00393 -0.00302 0.00026 -0.01807 0.07043 3 -0.00388 -0.00784 -0.00176 -0.03585 -0.05142 4 0.00011 0.00380 0.01529 0.35334 0.01401 5 0.00000 0.00004 -0.01272 -0.66454 0.01346 6 0.01626 0.00255 0.00004 0.00360 0.06885 7 -0.01313 -0.01030 -0.00090 -0.01394 -0.05240 8 0.00030 0.00926 0.03159 0.29145 -0.00313 9 -0.00643 -0.01924 -0.00639 -0.06723 -0.06106 10 -0.00041 0.01420 -0.05513 0.88004 -0.02043 (1) Lf 0.00016 -0.00765 0.00744 -0.38814 0.01777 Lb -0.00341 -0.00348 -0.04350 0.42938 -0.05471 (2) -0.00568 -0.00308 0.11297 -0.99783 -0.10148 (3) 0.00164 0.00491 -0.07868 0.54632 0.13018 K SA5 CMA5 AST5 DIS5 PTZ5 SA7 1 0.00000 0.00000 0.00089 0.19925 0.00537 0.00000 Lf 2 0.00005 0.00010 -0.00019 -0.04197 -0.02465 0.00000 3 -0.00006 -0.00030 0.00309 0.05851 0.02059 0.00000 4 0.00000 0.00001 -0.00278 -0.17371 -0.00664 0.00000 5 0.00000 0.00000 0.00140 0.29779 -0.00517 0.00000 6 0.000 45 0.00065 -0.00128 -0.06874 -0.03299 0.00001 Lb 7 -0.00038 -0.00086 0.00385 0.06245 0.02784 -0.00001 8 0.00001 0.00015 -0.00667 -0.24618 -0.00634 0.00000 9 -0.00013 -0.00038 0.00605 0.10153 0.03024 0.00000 10 -0.00001 0.00027 -0.00851 -0.05951 0.00708 0.00000 ( 1) Lf -0.00001 -0.00019 0.00100 0.04207 -0.00532 0.00000 Lb -0.00006 -0.00017 -0.00516 0.08734 0.02066 0.00000 (2) 0.00215 0.00210 0.02325 0.11002 0.04238 0.00044 (3) -0.00011 -0.00182 -0.01764 -0.23535 -0.04339 -0.00001 Table 2 Telephoto end K SA3 CMA3 AST3 DIS3 PTZ3 1 -0.00012 -0.00129 -0.00153 -0.02522 -0.00533 2 0.07407 -0.15959 0.03821 -0.04511 0.02461 3 -0.07297 0.12950 -0.02554 0.02573 -0.01796 4 0.00198 0.00570 0.00182 0.00645 0.00489 5 0.00000 0.00011 -0.00449 -0.02568 0.00470 6 0.30610 -0.62100 0.13998 -0.11093 0.02405 7 -0.24715 0.48029 -0.10370 0.07903 -0.01831 8 0.00567 0.01211 0.00287 0.00127 -0.00109 9 -0.12109 0.19893 -0.03631 0.03156 -0.02133 10 -0.00765 0.05210 -0.03943 0.10570 -0.00714 (1) Lf 0.00296 -0.02568 0.01292 -0.03815 0.00621 Lb -0.06413 0.12254 -0.04108 0.08095 -0.01912 (2) -0.04759 -0.01905 0.04255 -0.06852 -0.03545 (3) 0.10867 -0.07190 -0.01371 0.05029 0.04548 K SA5 CMA5 AST5 DIS5 PTZ5 SA7 1 0.00000 0.00000 0.00003 0.00058 0.00013 0.00000 Lf 2 0.00378 -0.01177 0.00036 0.00004 -0.00079 0.00023 3 -0.00467 0.01264 -0.00018 -0.00005 0.00061 -0.00035 4 0.00003 -0.00003 0.00001 -0.00043 -0.00024 0.00000 5 0.00000 -0.00002 -0.00015 0.00139 -0.00003 0.00000 6 0.03670 -0.11819 0.00751 -0.00661 -0.00013 0.00506 Lb 7 -0.03092 0.09610 -0.00552 0.00477 0.00010 -0.00437 8 0.00066 -0.00059 -0.00011 -0.00036 -0.00021 0.00008 9 -0.01079 0.03259 -0.00184 0.00146 0.00039 -0.00114 10 -0.00095 0.00630 -0.00199 0.00210 0.00044 -0.00014 (1) Lf -0.00086 0.00083 0.00021 0.00014 -0.00028 -0.00012 Lb -0.00530 0.01618 -0.00209 0.00276 0.00056 -0.00052 (2) 0.06153 0.00426 0.00182 -0.00011 0.00112 0.03223 (3) -0.05301 -0.04412 -0.00037 0.00050 -0.00148 -0.03257 TOTAL 0.00235 -0.02284 -0.00043 0.00329 -0.00008 -0.000 97 Table 1 above shows the values at the wide-angle end, and Table 2 shows the values at the telephoto end. In addition, the sum of aberration correction coefficients peculiar to the surface is shown except for the first lens group. K (1-4) and Lf are the front group, K (5-
10) and Lb are the rear group, (2) and (3) are the second and third groups.
It represents a lens group.

From these tables, the effect of spherical aberration, which is axial aberration, is small in the first lens group. On the other hand, it can be seen that the correction of off-axis aberrations, astigmatism and distortion, has a large effect within the first lens group. That is, in the lens system of this example, the front group effectively corrects the insufficient correction of the rear group in the astigmatism, and the front group corrects the excessive correction of the rear group in the distortion aberration. This is the ray diagram shown in FIG.
It can be seen that the off-axis light flux that enters the front lens group at an acute angle has a gentle angle of incidence when it strikes the rear lens group, and therefore it is understood that the correction action is shared.

In the present invention, in the conventional optical system based on the first lens group, it is recognized that it is unreasonable to widen the angle, and in order to widen the angle, the above-mentioned As described above, a lens component having a weak refractive power is added in front of the first lens group to make the incident angle to the first lens group easy for aberration correction. The added lens component is the front group of the first lens group, so to speak, the conventional first lens group is the rear group of the first lens group. It is intended to obtain a lens system. In this case, a single negative lens is considered as the simplest configuration in the front group, but it is effective to add a positive lens to the negative lens in order to correct aberrations better.

On the other hand, in order to prevent the diameter of the front lens from being reduced and the entrance pupil from becoming too far away, it is desirable that the conditions be described later. As described above, it is desirable that the first lens group uses at least one negative lens in the front lens group. On the other hand, it is desirable that the rear lens group be composed of at least one positive lens component and one negative lens component.

The condition (1) is related to the following conditions.
is doing. (2) 0.1 <φ 1 / φ w <1.25 (3) 1.1 <φ 12w / φ w <3.0 (4) 1.5 <β3T / β3w <4.0 where φ w is the refractive power of the entire system at the wide-angle end, φ 12w is
At the wide-angle end, the composite bending of the first lens group and the second lens group
Folding power, β3w, and β3T are magnifications of the third lens group, respectively. Article
The condition (2) defines the refractive power of the first lens group,
If the upper limit of this condition (2) is exceeded, aberration correction will become difficult.
It If the lower limit of condition (2) is exceeded, the movement during zooming will be delayed.
This is not preferable because the amount of movement is increased and miniaturization is maintained. conditions
(3) has a small total lens length of the first lens group and the second lens group.
In order to determine the desired refractive power from the viewpoint of aberration correction
Is a necessary condition. If the upper limit of this condition is exceeded, the size will be reduced.
Can achieve sufficient optical performance
It will be difficult. On the other hand, if the lower limit is exceeded, the lens system will become large.
Therefore, it is not preferable. Condition (4) is related to the scaling factor
Under the condition, if the lower limit is exceeded, even if a paraxial solution is obtained, it is realistic.
It becomes difficult to achieve a high zoom lens.

Further, the lens system of the present invention preferably satisfies the following conditions (5) and (6), focusing attention on paraxial rays and paraxial rays in the first lens group. (5) 0.5 <hB / hF <1.5 (6) 0.2 <AB / AF <2.0 where hF is the paraxial on-axis ray height incident on the front group of the first lens group at the wide-angle end. , HB is the paraxial ray height incident on the rear group of the first lens group at the wide-angle end, AF is the paraxial off-axis ray height incident on the front group of the first lens group at the wide-angle end, A
B is the paraxial off-axis ray height incident on the rear group of the first lens group at the wide-angle end.

The condition (3) is widened by forming the first lens group into an inverse telephoto type by giving the action of the front group as a negative group, or even if the front group is a converging system. This means that it has a weak positive refractive power. If the lower limit of this condition (5) is exceeded, the effect of correcting off-axis aberrations at the wide-angle end becomes weak. When the value exceeds the upper limit of the condition (5), the refractive power of the front group becomes strong, the number of constituent elements increases for aberration correction, and the lens system becomes large.

The condition (6) is also the same as the condition (5). If the lower limit of the condition is exceeded, the refractive power of the front unit becomes large, and if the upper limit is exceeded, it becomes difficult to correct aberrations at the wide-angle end.

As described above, the conditions (5) and (6) are for making the angle of the incident off-axis ray gentle and facilitating the aberration correction. That is, if these conditions are not satisfied, the effect of aberration correction works if the angle of view at the wide-angle end is on the telephoto side, but the effect of correcting off-axis aberrations decreases at ultra-wide angles.

The three-group zoom has been described above.
The gist of the present invention can be applied to the group zoom. That is, as shown in FIG. 44, in order from the object side, the first lens group having a positive refractive power, the second lens group having a positive refractive power, the third lens group having a positive refractive power, and the fourth lens group having a negative refractive power. The first lens group and the second lens group, the second lens group and the third lens group, and the third lens group and the fourth lens group. It has a double action,
The first lens group is made up of a front group and a rear group for widening the angle, and the same condition (1) as in the above-described three-group zoom is satisfied.

The states of light rays at the paraxial and thick lenses of the first lens group are shown in FIGS. 46, 47 and 48, respectively.
This is the case of FIG. 49.

[0038]

EXAMPLES Next, examples of the zoom lens of the present invention will be described. Example 1 f = 28.90 to 102.00 mm, F / 4.5 to F / 7.625, 2ω = 73.64 ° to 23.94 ° r1 = 160.7804 d1 = 1.2000 n1 = 1.74100 ν1 = 52.68 r2 = 34.8076 d2 = 6.9850 r3 d3 = 38.8887. = 1.53172 v2 = 48.90 r4 = 142.7690 d4 = D1 r5 = -194.6240 d5 = 1.0000 n3 = 1.83400 v3 = 37.16 r6 = 38.0459 d6 = 0.3520 r7 = 43.6 r8 = 73.6 r8 = 73.6 r8 = 74.50 n8 = 4. = 32.2002 d9 = 5.2460 n5 = 1.51823 ν5 = 58.96 r10 = -96.2536 d10 = D2 r11 = -498.7110 d11 = 1.0000 n6 = 1.78590 ν6 = 44.18 r12 = 15.0840 d12 = 0.8410 r13 = 24.1630 n7 = 1.7640 d13 = 2.7640 = -102.9802 d14 = 3.9120 r15 = -14.3361 d15 = 1.1100 n8 = 1.65830 ν8 = 53.44 r16 = -16.3753 d16 = 4.9610 r17 = ∞ (diaphragm) d17 = 3.6000 r18 = -79.9489 d18 = 2.1300 n9 = 1.66680 ν9 = 33.04 -51.9241 d19 = 0.5000 r20 = -555.5860 d20 = 3.0490 n10 = 1.54454 ν10 = 54.69 r21 = -26.8298 d21 = 0.1200 r22 = 103.1734 d22 = 0.6500 n11 = 1.80518 ν11 = 25.43 r23 = 17.2071 d23 = 5.4150 n12 = 1.60729 ν12 = 59.38 r24 = -26.0457 d25 = 1.2500894 0.8780 n13 = 1.77250 ν13 = 49.66 r26 = -22.7792 d26 = D3 r27 = -54.8870 d27 = 3.3170 n14 = 1.78472 ν14 = 25.71 r28 = -22.2644 d28 = 2.4970 r29 = -15.6872 (aspherical surface) d29 = 0.3600 n15 = 1.52492 ν15 51.77 r30 = -16.8658 d30 = 1.3200 n16 = 1.77250 ν16 = 49.66 r31 = 62.5760 Aspheric surface coefficient P = 1.0000, E = 0.30618 × 10 ^-4 , F = 0.10777 × 1
0 ^-6 , G = -0.18514 x 10 ^-9 , H = 0.20423 x 10 ^-11 f 28.90 54.44 102.00 D1 1.750 1.750 1.750 D2 1.500 16.298 22.421 D3 15.852 7.073 1.530 ｜ φf / φ1 ｜ = 0.65194, φ1 / φw = 0.246, φ12w / φw =
1.330 hB / hF = 1.1256, AB / AF = 0.8117, β3T / β3w = 3.0 Example 2 f = 28.92 to 102.02 mm, F / 4.5 to F / 7.625, 2ω = 73.6 ° to 23.94 ° r1 = -82.5283 d1 = 1.2500 n1 = 1.74100 ν1 = 52.68 r2 = 8479.1527 d2 = 1.0288 r3 = 109.7348 d3 = 2.2603 n2 = 1.53172 ν2 = 48.90 r4 = -234.4198 d4 = 0.7500 r5 = -104.1899 d5 = 0.36400616 = 0.8500 n3 = 0.8500 n3 = 0.8500 n3 r7 = 39.3253 d7 = 4.5192 n4 = 1.65844 ν4 = 50.86 r8 = -20126.4985 d8 = 0.1200 r9 = 38.2462 d9 = 5.5542 n5 = 1.65830 ν5 = 53.44 n6 = 16.37 n18 = 16.36 d11 r6 = 16.16d11 = 16. r12 = 12.1902 d12 = 0.7721 r13 = 20.1078 d13 = 3.1941 n7 = 1.78470 ν7 = 26.22 r14 = -324.9518 d14 = 2.9127 r15 = -12.2940 d15 = 0.6569 n8 = 1.65830 ν8 = 53.44 r16 = -14.2480 d16 ) D17 = 3.4906 r18 = -39.4065 d18 = 1.9818 n9 = 1.59270 ν9 = 3 5.29 r19 = -23.5086 d19 = 1.0128 r20 = -77.1442 d20 = 2.2237 n10 = 1.50137 ν10 = 56.40 r21 = -27.3780 d21 = 0.1200 r22 = 71.2472 d22 = 0.8500 n11 = 1.864666 ν11 = 23.78 r23 = 17.8516 n12 = 4.0993 = 58.94 r24 = -19.8521 d24 = 0.8500 r25 = -20.0533 d25 = 1.5717 n13 = 1.77250 ν13 = 49.66 r26 = -21.5906 d26 = D2 r27 = -49.9729 d27 = 3.4179 n14 = 1.78472 ν14 = 25.71 r28 = -20.53093 d29 = -13.9632 (aspherical surface) d29 = 0.1000 n15 = 1.52492 ν15 = 51.77 r30 = -14.0500 d30 = 0.9444 n16 = 1.78590 ν16 = 44.18 r31 = 57.0622 Aspherical coefficient P = 1.0000, E = 0.46567 × 10 ^-4 , F = 0.16608 × 1
0 ^-6 , G = -0.40245 × 10 ^-9 , H = 0.76140 × 10 ^-11 f 28.92 54.39 102.02 D1 1.250 15.540 20.970 D2 12.853 5.873 1.207 ｜ φf / φ1 ｜ = 0.17379, φ1 / φw = 0.304, φ12w / φw =
1.404 hB / hF = 1.0233, AB / AF = 0.9179, β3T / β3w = 3.329 Example 3 f = 24.50 to 76.49 mm, F / 4.5 to F / 7.5, 2ω = 82.88 ° to 31.58 ° r1 = 96.5532 d1 = 1.2000 n1 = 1.69350 ν1 = 53.23 r2 = 27.7448 d2 = 11.6550 r3 = -91.4665 d3 = 1.2066 n2 = 1.78470 ν2 = 26.22 r4 = -303.5278 d4 = 0.1500 r5 = 3.060 797 = 6. ＝ 37.1151 d7 ＝ 5.0200 n4 ＝ 1.60311 ν4 ＝ 60.70 r8 ＝ -206.3245 d8 ＝ D1 r9 ＝ 57.4357 d9 ＝ 1.0000 n5 ＝ 1.67790 ν5 ＝ 55.33 r10 ＝ 16.3022 (aspherical surface) d10 ＝ 1.5109 r11 ＝ 36.997 = 29.24 r12 = -33.4657 d12 = 1.1015 r13 = -23.8559 d13 = 1.1100 n7 = 1.83400 ν7 = 37.16 r14 = -125.8813 d14 = 4.7035 r15 = ∞ (diaphragm) d15 = 3.4988 r16 = -21.5971 d16 = 2.1300 n8 = 8350 65.94 r17 = -22.7796 d17 = 3.9083 r18 = -54.9728 d18 = 2.5000 n9 = 1.5182 1 ν9 = 65.04 r19 = -18.0505 d19 = 0.1200 r20 = 52.5661 d20 = 0.8500 n10 = 1.84666 ν10 = 23.78 r21 = 21.2304 d21 = 4.0000 n11 = 1.56873 ν11 = 63.16 r22 = -58.4819 d22 = 0.8950 r23 = 7950 r23 = 7950 1.77250 ν12 = 49.66 r24 = -204.8691 d24 = D2 r25 = -76.9580 d25 = 3.3170 n13 = 1.74000 ν13 = 28.29 r26 = -25.1526 d26 = D2 r27 = -19.5931 (aspherical surface) d27 = 0.3600 n14 = 1.52492 ν14 = 51.77 -23.2468 d28 = 1.200 200 n15 = 1.77250 ν15 = 49.66 r29 = 35.1917 Aspheric coefficient (10th surface) P = 1.0000, E = 0.15173 × 10 ^-4 , F = 0.
18351 x 10 ^-6 , G = -0.108 33 x 10 ^-8 , H = 0.28490 x 10
^-10 (27th surface) P = 1.0000, E = 0.22735 × 10 ^-4 , F = 0.
29706 x 10 ^-7 , G = -0.30210 x 10 ^-9 , H = 0.83428 x 10
^-12 f 24.50 45.02 76.49 D1 0.850 16.915 22.361 D2 12.830 5.031 0.510 ｜ φf / φ1 ｜ ＝ 2.13856, φ1 / φw = 0.175, φ12w / φ
w = 1.365 hB / hF = 1.2347, AB / AF = 0.5986, β3T / β3w = 2.727 Example 4 f = 29.01 to 105.43 mm, F / 4 to F / 7.65, 2ω = 73.42 ° to 23.2 ° r1 = 123.2807 d1 = 1.2000 n1 = 1.69680 ν1 = 55.52 r2 = 28.1453 d2 = 7.0560 r3 = 31.7325 d3 = 5.4876 n2 = 1.53172 ν2 = 48.90 r4 = 302.3165 d4 = D3 r6 = 125.1445 d5 = 3. r7 = 40.6740 d7 = 3.6156 n4 = 1.65844 ν4 = 50.86 r8 = -1157.9848 d8 = 0.1500 r9 = 32.3632 d9 = 5.6348 n5 = 1.51823 ν5 = 58.96 r10 = -60.9035 d10 = 116.0611 = D21.0 r11 = D2 1.04 = 11. 44.18 r12 = 16.2024 d12 = 0.9097 r13 = 31.3832 d13 = 2.9131 n7 = 1.78470 ν7 = 26.22 r14 = -49.7711 d14 = 3.5341 r15 = -18.0019 d15 = 1.2081 n8 = 1.65830 ν8 = 53.44 r16 = -22.395 Aperture) d17 = 3.4676 r18 = -115.0000 d18 = 2.1300 n9 = 1.68893 ν9 = 31.08 r19 = -64.5600 d19 = 0.5000 r20 = 484.4333 d20 = 3.3939 n10 = 1.54739 ν10 = 53.55 r21 = -26.1713 d21 = 0.5903 r22 = 146.1389 d22 = 0.4350 n11 = 1.78472 ν11 = 25.71 r23 = 17.3114 d23 = 5.4869 n12 = 1.583. -25.9767 d24 = 1.2500 r25 = -19.9068 d25 = 1.4830 n13 = 1.74100 ν13 = 52.68 r26 = -20.9013 d26 = D3 r27 = -38.0869 d27 = 2.7902 n14 = 1.84666 ν14 = 23.78 r28 = -21.4684 d28 = 1.26534 r29 Aspherical surface) d29 = 0.3593 n15 = 1.52492 ν15 = 51.77 r30 = -17.4211 d30 = 1.3500 n16 = 1.77250 ν16 = 49.66 r31 = 82.1742 aspherical coefficient P = 1.0000, E = 0.20587 × 10 ^-4 , F = 0.86201 × 1
0 ^-7 , G = -0.48242 x 10 ^-9 , H = 0.27293 x 10 ^-11 f 29.01 54.44 105.43 D1 1.750 1.750 1.750 D2 1.500 15.621 21.576 D3 17.439 8.661 2.636 | φf / φ1 | = 0.18545, φ1 / φw = 0.322, φ12w / φw
= 1.349 hB / hF = 1.134, AB / AF = 0.8547, β3T / β3w = 2.973 Example 5 f = 29.51 to 131.00 mm, F / 4.5 to F / 8.25, 2ω = 72.48 ° to 18.76 ° r1 = 147.7015 d1 = 0.8500 n1 = 1.74100 ν1 = 52.68 r2 = 39.8775 d2 = 6.9732 r3 = 34.9579 d3 = 4.4400 n2 = 1.53172 ν2 = 48.90 r4 = -509.1641 d4 = D1 r5 = -55.5614 d5 = 1.836400 n3 = 0.8600 n3. r7 = 45.0582 d7 = 3.6100 n4 = 1.65844 ν4 = 50.86 r8 = -134.9701 d8 = 0.1200 r9 = 36.3870 d9 = 4.4600 n5 = 1.50137 ν5 = 56.40 r10 = -55.5290 d10 = D2 r0 = 60.5611 = -74.11 44.18 r12 = 15.5103 d12 = 0.7341 r13 = 24.6834 d13 = 2.6600 n7 = 1.78470 ν7 = 26.22 r14 = -63.3984 d14 = D3 r15 = -13.9591 d15 = 0.9163 n8 = 1.65830 ν8 = 53.44 r16 = -16.2221 Aperture) d17 = 3.3080 r18 = -77.7267 d18 = 1.7100 n9 = 1.66680 ν9 = 33.04 19 = -56.3440 d19 = 0.1400 r20 = -322.6649 d20 = 2.3300 n10 = 1.50137 ν10 = 56.40 r21 = -24.8971 d21 = 0.1200 r22 = 74.2271 d22 = 0.5300 n11 = 1.85018 ν11 = 25.43 r23 = 17.1956 d12 = 5.10311 60.70 r24 = -24.4180 d24 = 1.0490 r25 = -20.8299 d25 = 0.8800 n13 = 1.77250 ν13 = 49.66 r26 = -22.2142 d26 = D4 r27 = -50.1298 d27 = 3.2000 n14 = 1.78472 ν14 = 25.71 r28 = -21.5995 d28 = 2.3876 -14.9318 (aspherical surface) d29 = 0.4500 n15 = 1.52492 ν15 = 51.77 r30 = -15.1591 d30 = 1.1900 n16 = 1.77250 ν16 = 49.66 r31 = 52.7870 Aspherical coefficient P = 1.0000, E = 0.45142 × 10 ^-4 , F = 0.15406 × 1
0 ^-6 , G = -0.58035 x 10 ^-9 , H = 0.42319 x 10 ^-11 f 29.51 62.50 131.00 D1 1.460 1.460 1.460 D2 0.766 17.061 22.292 D3 4.073 3.798 3.630 D4 15.086 6.568 1.369 ｜ φf / φ1 | = 0.34602, φ1 / φw = 0.360, φ12w / φw =
1.385 hB / hF = 1.0767 AB / AF = 0.9845, β3T / β3w = 3.442 Example 6 f = 29.30 to 102.00 mm, F / 4.6 to F / 7.65, 2ω = 72.88 ° to 23.94 ° r1 = -60.5111 d1 = 1.2500 n1 = 1.74100 ν1 = 52.68 r2 = -103.1603 d2 = 0.2000 r3 = 51.3114 d3 = 2.6500 n2 = 1.53172 ν2 = 48.90 r4 = 254.0371 d4 = 1.0500 r5 = -1437 7.6 = 68.77 = 637 = 6. ＝ 28.5843 d7 ＝ 4.0000 n4 ＝ 1.65844 ν4 ＝ 50.86 r8 ＝ 451.3443 d8 ＝ 0.1200 r9 ＝ 47.3480 d9 ＝ 4.0500 n5 ＝ 1.65830 ν5 ＝ 53.44 r10 ＝ －73.2687 d10 ＝ D1 r11 ＝ 61.70.512 = 11.3110 d12 = 0.6696 r13 = 21.2161 d13 = 1.9980 n7 = 1.78470 ν7 = 26.22 r14 = -75.8136 d14 = 5.3056 r15 = ∞ (diaphragm) d15 = 3.6513 r16 = -18.5732 d16 = 2.1356 n8 = 1.59551 ν8 = 39.21 d17 = 0.5046 r18 = -31.4506 d18 = 1.5121 n9 = 1.50137 ν9 = 56.40 r 19 = -18.2746 d19 = 0.1200 r20 = 75.5019 d20 = 0.8500 n10 = 1.84666 v10 = 23.78 r21 = 19.0505 d21 = 3.9996 n11 = 1.60881 v11 = 58.94 r22 = -17.4005 d22 = D2 r23 = -45.2876 d23 = 3.02 n12 = 3.02 n12 = 3.02 25.71 r24 = -18.7253 d24 = 2.6527 r25 = -12.9546 (aspherical surface) d25 = 0.1000 n13 = 1.52492 ν13 = 51.77 r26 = -14.0500 d26 = 1.0000 n14 = 1.79952 ν15 = 42.24 r27 = 119.6924 Aspheric coefficient P = 1.0000, E = 0.37563 x 10 ^-4 , F = 0.36933 x 1
0 ^-6 , G = -0.27582 x 10 ^-8 , H = 0.24748 x 10 ^-10 f 29.30 54.52 102.00 D1 1.136 13.805 20.500 D2 15.118 6.870 0.998 | φf / φ1 | = 0.25624, φ1 / φw = 0.385, φ12w / φw =
1.346 hB / hF = 0.9986, AB / AF = 1.0469, β3T / β3w =
2.651 where r1, r2, ... are the radii of curvature of each lens surface, d1
, D2, ... are the wall thickness and lens spacing of each lens, n1
, N2, ... is the refractive index of each lens, ν1, ν2, ...
Is the Abbe number of each lens. Example 1 is a wide-angle zoom lens having a focal length of 29.0 to 105 mm, which is shown in FIG. The lens system of this embodiment does not restrict the overall length so much and suppresses it to less than 90 mm at the wide-angle end, but has stable and good optical performance over the entire zoom range. The aberrations of this embodiment are as shown in FIGS. 7 to 12, and FIGS. 7, 9 and 11 show aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object at infinity, FIG. 8, and FIG. 1
0 and FIG. 12 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object of 2.0 mm, respectively. Example 2
Is a wide-angle zoom lens having a focal length of 28.9 to 102 mm, which has the configuration shown in FIG. Unlike Example 1, this example has a slightly longer overall length because an image plane correcting lens is arranged in the second lens group. The aberrations in this example are as shown in FIGS.
FIGS. 15 and 17 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, for an object at infinity, and FIGS.
6 and 18 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object distance of 2.0 m, respectively. The third embodiment is a wide-angle zoom lens including a super wide angle with a focal length of 24.5 to 76.5 mm. As shown in FIG. 3, the front group in the first lens group consists of one negative lens component, and
It is an example in which the lens group has characteristics. In terms of aberration correction, an aspherical surface is used for the second lens group as well as the third lens group. The aberrations in this example are as shown in FIGS. 19 to 24. That is, FIGS. 19, 21, and 22 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object at infinity, respectively, and FIGS.
It is an aberration curve figure in the wide-angle end, an intermediate focal length, and a telephoto end with respect to an object of 0 m. Example 4 has a focal length of 29.0.
It is a wide-angle zoom lens of ~ 105 mm. This example
With the lens configuration shown in FIG. 4, the overall length is relatively long. As a result, the optical performance was improved. The aberrations of the fourth embodiment are as shown in FIGS. Of these figures, FIG. 25, FIG. 27, and FIG. 29 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, for an object at infinity, and FIGS. FIG. 6 is an aberration curve diagram at the wide-angle end, the intermediate focal length, and the telephoto end for the Example 5 has a focal length of 2
A wide-angle zoom lens with a high zoom ratio of 9.5 to 131 mm. This embodiment is a four-group zoom lens with a configuration as shown in FIG. The total length of the wide-angle end is shortened to 83.6, and the back focus is 8.92. The aberrations in this example are as shown in FIGS.
1, FIG. 33, and FIG. 35 are the wide-angle end for an object at infinity,
32, 34, and 36 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object of 2.0 m respectively. In this embodiment, the correction of spherical aberration at the telephoto end is slightly difficult, but is practically sufficient. In Example 6, the focal length is 2
It is a wide-angle zoom lens of 9.3 to 102 mm, and the total length is 68.25 at the wide-angle end. In this embodiment, as shown in FIG. 6, the first lens group is composed of a front group composed of a negative lens and a positive lens, and a rear group composed of one negative lens and two positive lenses. There is. Further, the third lens group uses an aspherical surface on the assumption that a synthetic resin material is used. The back focus is 9.52 at the wide-angle end, which is sufficiently secured. The aberration states of the sixth embodiment are as shown in FIGS. 37 to 42. FIGS. 37, 39, and 41 show aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object at infinity, respectively. 40 and 42 are aberration curve diagrams at the wide-angle end, the intermediate focal length, and the telephoto end for an object of 2.0 m, respectively. In Example 6, the overall length was shortened, so that the lateral chromatic aberration at the wide-angle end could not be sufficiently corrected with the g-line, but the overall correction state was good. Further, the distortion aberration is a relatively monotonous change. Further, the bending of astigmatism in the meridional direction at the wide-angle end is an effect of the aspherical surface of the third lens group. The focusing of the lens system in the above-described embodiment is the second in the case of the three-group zoom lens.
This is performed by the lens group, and in the case of a 4-group zoom lens, it is performed by the second to third lens groups. Examples other than Example 6,
At the time of focusing, a lens component for short-distance aberration correction is provided on the most image plane side in the focusing lens unit, and this lens component is fixed and the remaining lens components are moved to perform focusing and aberration correction. The shape of the aspherical surface used in the above embodiment is represented by the following equation when the optical axis direction is the x axis and the direction perpendicular to the optical axis is the y axis. However, r is a radius of curvature near the aspherical vertex, P is a conic constant, and E, F, G, H, ... Are aspherical coefficients.

[0039]

As described above, according to the present invention, by making the constitution of the first lens group characteristic, this type of zoom which is conventionally considered to be disadvantageous in widening the angle without increasing the total length and outer diameter too much. In the lens, it was possible to achieve a wide angle while maintaining good optical performance.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a sectional view of a second embodiment.

FIG. 3 is a sectional view of a third embodiment.

FIG. 4 is a sectional view of a fourth embodiment.

FIG. 5 is a sectional view of a fifth embodiment.

FIG. 6 is a sectional view of a sixth embodiment.

7 is an aberration curve diagram at the wide-angle end for an object at infinity according to Example 1. FIG.

FIG. 8 is an aberration curve diagram for a 2.0 m object in Example 1 at the wide-angle end.

9 is an aberration curve diagram at an intermediate focal length for an infinitely distant object in Example 1. FIG.

FIG. 10 is an aberration curve diagram for a 2.0 m object in Example 1 at an intermediate focal length.

FIG. 11 is an aberration curve diagram at the telephoto end for an object at infinity in Example 1.

12 is an aberration curve diagram at the telephoto end for an object of 2.0 m in Example 1. FIG.

FIG. 13 is an aberration curve diagram at the wide-angle end for an object at infinity according to Example 2.

FIG. 14 is an aberration curve diagram at the wide-angle end for an object of 2.0 m in Example 2.

FIG. 15 is an aberration curve diagram at an intermediate focal length for an object at infinity according to Example 2;

FIG. 16 is an aberration curve diagram for Example 2.0 at an intermediate focal length for an object of 2.0 m.

FIG. 17 is an aberration curve diagram at the telephoto end for an infinitely distant object in Example 2.

FIG. 18 is an aberration curve diagram for a 2.0 m object in Example 2 at the telephoto end.

FIG. 19 is an aberration curve diagram at the wide-angle end for an object at infinity according to Example 3;

FIG. 20 is an aberration curve diagram for a 2.0 m object in Example 3 at the wide-angle end.

FIG. 21 is an aberration curve diagram at an intermediate focal length for an object at infinity according to Example 3;

FIG. 22 is an aberration curve diagram at an intermediate focal length for a 2.0 m object in Example 3;

FIG. 23 is an aberration curve diagram for the object at infinity according to Example 3 at the telephoto end.

FIG. 24 is an aberration curve diagram for Example 2.0 at the telephoto end for a 2.0 m object.

FIG. 25 is an aberration curve diagram at the wide-angle end for an object at infinity according to Example 4;

FIG. 26 is an aberration curve diagram for a 2.0 m object in Example 4 at the wide-angle end.

FIG. 27 is an aberration curve diagram at an intermediate focal length for an object at infinity according to Example 4;

FIG. 28 is an aberration curve diagram for a 2.0 m object in Example 4 at an intermediate focal length.

29 is an aberration curve diagram at the telephoto end for an object at infinity according to Example 4. FIG.

FIG. 30 is an aberration curve diagram at the telephoto end for an object of 2.0 m in Example 4.

FIG. 31 is an aberration curve diagram at the wide-angle end for an object at infinity in Example 5.

FIG. 32 is an aberration curve diagram for a 2.0 m object in Example 5 at the wide-angle end.

FIG. 33 is an aberration curve diagram at an intermediate focal length for an object at infinity according to Example 5;

FIG. 34 is an aberration curve diagram for a 2.0 m object in Example 5 at an intermediate focal length.

FIG. 35 is an aberration curve diagram for the object at infinity according to Example 5 at the telephoto end.

FIG. 36 is an aberration curve diagram for Example 2.0 at the telephoto end for an object of 2.0 m.

FIG. 37 is an aberration curve diagram at the wide-angle end for an object at infinity in Example 6.

FIG. 38 is an aberration curve diagram for a 2.0 m object in Example 6 at the wide-angle end.

FIG. 39 is an aberration curve diagram for the object at infinity in Example 6 at the intermediate focal length.

FIG. 40 is an aberration curve diagram for a 2.0 m object in Example 6 at an intermediate focal length.

FIG. 41 is an aberration curve diagram for the object at infinity according to Example 6 at the telephoto end.

42 is an aberration curve diagram for Example 2.0 at the telephoto end for an object of 2.0 m.

FIG. 43 is a diagram showing a basic configuration in the case of a three-group zoom according to the present invention.

FIG. 44 is a diagram showing a basic configuration of a four-group zoom according to the present invention.

FIG. 45 is a diagram showing how off-axis rays are incident on the front group and the rear group of the first lens group.

FIG. 46 is a diagram showing the state of paraxial rays at the wide-angle end of the first lens group.

FIG. 47 is a diagram showing a situation of paraxial rays at the telephoto end of the first lens.

FIG. 48 is a diagram showing a state of light rays at a thick lens at the wide-angle end of the first lens group.

FIG. 49 is a diagram showing a situation of paraxial rays in the first lens group.

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[Procedure amendment]

[Submission date] April 7, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 7]

[Figure 8]

FIG. 43

FIG. 44

FIG. 45

[Figure 3]

[Figure 9]

[Figure 10]

FIG. 34

FIG. 38

FIG. 46

[Figure 4]

[Figure 5]

FIG. 11

[Fig. 12]

FIG. 47

FIG. 49

[Figure 6]

[Fig. 13]

FIG. 14

FIG. 48

FIG. 15

FIG. 16

FIG. 17

FIG. 18

FIG. 19

FIG. 20

FIG. 21

FIG. 22

FIG. 23

FIG. 24

FIG. 25

FIG. 26

FIG. 27

FIG. 28

FIG. 29

FIG. 30

FIG. 31

FIG. 32

FIG. 33

FIG. 35

FIG. 36

FIG. 37

FIG. 39

FIG. 40

FIG. 41

FIG. 42

Claims (2)

[Claims] 1. A first lens group having a positive refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power in order from the object side.
The second lens group and the third lens group are changed to change the distance between the first lens group and the second lens group, and the first lens group is changed to the following condition (1 ) A wide-angle zoom lens characterized by being composed of two groups, a front group and a rear group, which satisfy the above condition. (1) | φf / φ1 | <6.0 where φf is the refracting power of the front group and φ1 is the refracting power of the first lens group. 2. A first lens unit having a positive refracting power, a second lens unit having a positive refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a negative refracting power in order from the object side. The lens unit is configured to change the distance between the first lens unit and the second lens unit, the distance between the second lens unit and the third lens unit, and the distance between the third lens unit and the fourth lens unit. The first one
A wide-angle zoom lens characterized in that the lens unit comprises two groups, a front group and a rear group, which satisfy the following condition (1). (1) | φf / φ1 | <6.0 where φ1 is the refractive power of the first lens group and φf is the refractive power of the front group.