JPH07151975A - Zoom lens - Google Patents

Abstract

PURPOSE:To obtain a high angle of view and high variable power ratio and optical performance high over the entire variable power range by specifying the moving conditions of respective lens groups in variable magnification and specifying focal lengths and lateral magnification. CONSTITUTION:The front group consisting of the first group L2 having a positive refracting power, and the second group L2 having a negative refracting power has the positive combined refracting power at the wide angle end and the rear group consists of the fourth group L4 having a positive refracting power and the fifth group L5 having a negative refracting power. The first to third groups L1 to L3 move in such a manner that the combined refracting power of the front group is made narrower than at the wide angle end and the fourth group L4 and the fifth group L5 move in such a manner that the spacing therebetween is made narrow at the time of the variable magnification from the wide angle end to the telephoto end. The focal length f1 of the i-th group, the focal length fw of the entire system at the wide angle end and the lateral magnification betaiw at the wide angle end of the i-th group satisfy the conditions 0-45<1f5/fw1<1.5 and 1.1<beta5w<1.9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact zoom lens having a high zoom ratio and a wide angle of view, which is suitable for a lens shutter camera, a video camera, etc. The present invention relates to a zoom lens which is excellent in portability and has a shortened distance from one lens surface to an image surface.

[0002]

2. Description of the Related Art Recently, in a lens shutter camera, a video camera, etc., a compact zoom lens having a short total lens length has been demanded as the camera becomes smaller. In particular, lens shutter cameras are becoming smaller and smaller due to the development of peripheral technologies such as zoom driving electric circuits. There is.

Conventionally, a so-called two-group zoom lens composed of two lens groups having positive and negative refracting power has been mainly used as a zoom lens for a lens shutter. Since the two-group zoom lens has a simple lens structure and a moving mechanism at the time of zooming, it has advantages such as downsizing of the camera and relatively low cost. However, since the zooming action must be performed by only one lens group, the zooming ratio is about 1.6 to 2 times, and forcibly increasing the zooming ratio leads to enlargement of the lens system. At the same time, it becomes difficult to maintain high optical performance.

On the basis of a two-group zoom lens, the first group is divided into two lens groups having a positive refractive power, and as a whole,
A three-group zoom lens aiming at high zooming as a three-group configuration of positive and negative refracting powers is disclosed in, for example, Japanese Patent Laid-Open Nos. 3-282409, 4-37810, and 4-7651.
It is proposed in Japanese Patent Publication No. 1 and the like.

However, if an attempt is made to achieve a wide-angle zoom lens system having a half angle of view of 35 ° or more with this lens group configuration, the change in the entrance pupil position during zooming becomes large. For this reason, it becomes very difficult to suppress aberration variation due to zooming when achieving high zooming.

In addition to this, a zoom lens having a wide angle of view and a high zoom ratio, which has a half field angle at the wide-angle end of about 38 ° and a zoom ratio of about 3.5 times, has been proposed, for example. Kaihei 2-
72316 and JP-A-3-249614. However, these zoom lens systems have a large front lens diameter and a large overall lens length, and are not always sufficient as photographing lenses for compact cameras.

Particularly when applied to a camera using an external viewfinder, there is a problem that the lens barrel covers the photographing field of view of the viewfinder at the wide-angle end. Further, as a result, there arises a problem that the viewfinder arrangement and the camera form are restricted.

[0008]

Generally, in a zoom lens, if the refractive power of each lens group is strengthened, the amount of movement of each lens group for obtaining a predetermined zoom ratio is reduced, and the total lens length is shortened. High zoom ratio is possible. However, if the refracting power of each lens unit is simply increased, the aberration variation due to zooming becomes large, and particularly when achieving high zooming and widening the angle of view, it is necessary to obtain good optical performance over the entire zooming range. There is a problem that it becomes difficult.

The present invention is composed of five lens groups as a whole, and the moving conditions and refractive power of each lens group during zooming are appropriately set, and the photographing field angle at the wide angle end is about 64 to 72 °.
It is an object of the present invention to provide a zoom lens having high optical performance over the entire zoom range with a zoom ratio of about 3.5.

[0010]

A zoom lens according to the present invention comprises three lenses, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power. And a rear lens group consisting of two lens groups, a front lens group having positive power and a fourth lens group having positive power and a fifth lens group having negative power. During zooming from the wide-angle end to the telephoto end, the first, second, and third groups move such that the combined refractive power of the front group weakens at the telephoto end as compared with the wide-angle end, The groups are moving so that their intervals are narrowed. When the focal length of the i-th group is fi, the focal length of the entire system at the wide-angle end is fW, and the lateral magnification at the wide-angle end of the i-th group is βiW, 0 .45 <| f5 / fW | <1.5 (1) 1.1 <β5W <1.9 (2) Satisfies the condition It is characterized in Rukoto.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the paraxial refractive power arrangement of the zoom lens of the present invention. In FIG. 1, (A) is the wide-angle end,
(B) shows the telephoto end. 2 to 5 are sectional views of lenses at the wide-angle end according to Numerical Embodiments 1 to 4 of the present invention. 6 to 17 are various aberration diagrams of Numerical Examples 1 to 4 of the present invention.

In the figure, LF is a front lens group having a positive refractive power, LR is a rear lens group, SP is a diaphragm, and IP is an image plane. Li (i = 1 to 1
5) is the i-th group. The arrows indicate the direction of movement of each lens group when zooming from the wide-angle side to the telephoto side.

The front lens group LF includes a first lens group L1 having a positive refractive power, a second lens group L2 having a negative refractive power, and a third lens group L3 having a positive refractive power.
It consists of two lens groups, and the combined refractive power at the wide-angle end is positive. The rear lens group LR is the fourth lens unit L4 having a positive refractive power.
And the fifth lens unit L5 having negative refracting power.

Upon zooming from the wide-angle end to the telephoto end, both the first, second, and third lens units move toward the object side, and the second lens unit moves while changing the relative positional relationship with the other lens units. The composite refractive power of the front lens group moves so that it becomes weaker at the telephoto end than at the wide-angle end. Further, the fourth group and the fifth group move toward the object side so that the distance between them becomes narrow. At this time, the distance between the third lens unit and the fourth lens unit is moved so as to be larger at the telephoto end than at the wide-angle end. This made it independent
The synthetic system of the group 4 and the group 4 is designed to be multiplied with the variation of magnification. Then, the focal length of the fifth lens unit and the lateral magnification at the wide-angle end are set according to conditional expressions (1) and (2), whereby the predetermined zoom ratio and wide angle of view are effectively achieved, and the lens We are trying to downsize the entire system. Also preferably, conditional expression (1),
(2) is preferably in the following range.

0.6 <| f5 / fW | <0.9 (1 ') 1.2 <β5W <1.55 (2') ) By taking the above range, further high performance can be achieved.

In the present invention, the combined refractive power of the first group and the second group is negative at the wide-angle end, and the front group as a whole is a retrofocus type from the third group of positive refractive power. As a result, the front principal point of the front group is located on the image plane side, and interference between lens surfaces of the front group and the rear group is prevented while facilitating widening of the field angle. The first lens group has a positive refractive power, and the second lens group has a second refractive power.
The total length of the retrofocus type front lens group is shortened by bringing the position of the rear principal point in the combined system of the first lens group and the second lens group at the wide-angle end to the object side by using the lens group as a negative refractive power. Further, the first lens group has a positive refractive power to favorably correct positive distortion at the wide-angle end. Then, the fourth group is extended toward the object side to focus from an infinitely distant object to a short-distance object.

In the zoom lens of the present invention, the focal length f of the entire lens system is expressed by the following equation.

F = fA · β4 · β5 (β4> 0, β5> 0) (a) where fA is the composite focal length of the front group, and βi is the lateral magnification of the i-th group. .

In the present invention, as can be understood from the expression (a), when the magnification is changed from the wide-angle end to the telephoto end, the lateral magnifications β4 and β5 are increased and the combined focal length fA of the front lens unit is increased. By (weakening the composite refractive power of the front group), more efficient zooming is performed. In addition, the distance between the fourth lens unit having a positive refractive power and the fifth lens unit having a negative refractive power is made narrower (decreased) at the telephoto end than at the wide-angle end to give a zooming effect to the fifth lens unit. This makes it easy to achieve high zoom ratios. In addition, the rear group is designed to have a more divergent (negative) refractive power at the telephoto end, and a telephoto type (telephoto type) is configured with the front group having a positive composite refractive power to reduce the size of the entire lens system. There is.

In the present invention, by adopting the paraxial refractive power arrangement as shown in FIG. 1, the photographing field angle is widened so that the focal length at the wide angle end becomes smaller than the diagonal length of the screen.

Specifically, the front group comprises a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power,
At the time of zooming from the wide-angle end to the telephoto end, each lens unit moves toward the object side so that the distance between the first and second groups increases and the distance between the second and third groups decreases. This enhances the scaling effect of the front group.

In the present invention, the first group and the third group are moved integrally for simplification of the mechanism, but they may be moved independently. According to this, the degree of freedom in design can be increased.

In the present invention, in the above lens structure, by satisfying the conditional expressions (1) and (2), the overall size of the lens system is reduced, and high optical performance is obtained over the entire zoom range. .

Next, the technical meanings of the above conditional expressions will be described.

Conditional expression (1) relates to the negative refracting power of the fifth lens group, and is mainly for effectively changing the magnification. If the negative refractive power of the fifth lens unit becomes weaker than the upper limit value of the conditional expression (1), the zooming effect of the lens unit becomes weak at the time of zooming, so that a constant zoom ratio is obtained. Therefore, the amount of movement of each lens group must be increased, which increases the total lens length.

Further, if the lower limit of conditional expression (1) is exceeded, at the wide-angle end, the lens system has positive composite refractive power of the first to fourth groups and negative refractive power of the fifth group. The action as a telephoto type becomes too strong.

As a result, the back focus of the lens system becomes too short, the outer diameter of the lens of the fifth lens unit becomes large in order to secure a constant amount of peripheral light, and at the same time, the refractive power of the lens unit becomes strong. Since it becomes too much, high-order field curvature and astigmatism occur, which makes it difficult to correct them.

Conditional expression (2) relates to the lateral magnification at the wide-angle end of the fifth lens unit.

Now, when the back focus of the lens system at the wide-angle end is BfW, it can be expressed as BfW = f5.multidot. (1-.beta.5W).

Therefore, in the present invention, the total length of the lens system and various aberrations are corrected in a well-balanced manner by appropriately setting the values of the conditional expression (2) together with the conditional expression (1).

If the upper limit of conditional expression (2) is exceeded, the back focus becomes longer than necessary, the total lens length increases, and it becomes difficult to make the lens compact. On the other hand, when the value goes below the lower limit, the back focus becomes too short and the outer diameter of the fifth lens unit increases, which is not good.

In the present invention, it is preferable to configure each lens group as follows in order to widen the angle of view while reducing the variation of aberration due to zooming and to secure high optical performance over the entire screen.

(1) When the composite refractive power of the front group at the wide-angle end is _φ123W , 0.3 <fW · _φ123W <1.2 (3) 0.6 < | F2 / fW | <3.0 It is preferable to satisfy the condition (4).

Conditional expression (3) relates to the refractive power of the front lens group. When the upper limit of conditional expression (3) is exceeded, the refractive power of the front lens group becomes too strong at the wide-angle end, and the action of the telephoto system becomes strong. It becomes difficult to obtain the back focus. or,
When the value goes below the lower limit, the refractive power of the front lens group becomes too weak, and the total lens length increases. At the same time, the refractive power of the rear lens group must be strengthened to maintain the focal length at the wide-angle end. It becomes difficult to balance.

Conditional expression (4) relates to the negative refracting power of the second lens unit. If the upper limit of conditional expression (4) is exceeded, the second conditional expression (4) is satisfied.
Since the refracting power of the group becomes too weak, the amount of movement of the lens group at the time of zooming becomes large, leading to an increase in the lens system. On the other hand, when the value goes below the lower limit, the refracting power of the second lens unit becomes too strong and high-order spherical aberration is strongly generated, which makes it difficult to correct this.

In the present invention, the upper and lower limits of the above conditional expressions (3) and (4) are set in order to correct the optical performance satisfactorily while shortening the total lens length at the wide-angle end in particular. _{Set as} follows: 0.35 <fW · _φ123W <0.9 (3a) 0.75 <| f2 / fW | <2.0 (4a) Good to do.

(2) When the composite refractive power of the front group at the telephoto end is φ _123T and the zoom ratio is Z, 0.6 <f3 / fW <2.0 .....・ ・ ・ ・ (5) 0.2 <(φ _123W / φ _123T ) / Z <0.8 ・ ・ ・ ・ (6) 0.25 <β4W <0.7 ・ ・ ・ ・(7) 0.1 <f5 · (1−β5W) / fW <0.36 ··· (8) It is preferable to satisfy the condition.

Conditional expression (5) relates to the positive refracting power of the third lens unit.
Since the refracting power of the group becomes weak, the amount of movement of the lens group at the time of zooming increases, leading to an increase in the lens system. When the value goes below the lower limit, the refractive power of the third lens unit becomes too strong, and accordingly, the negative refractive power of the second lens unit must be strengthened or the moving amount of the second lens unit must be increased due to zooming. Come on. In addition, the sharing of the magnification with respect to the rear group becomes large, which is not good.

Conditional expression (6) relates to the zoom ratio of the front group. If the upper limit of conditional expression (6) is exceeded, the variable magnification share in the front group will become too large, and the refracting power of the lens groups in the front group will become strong, or the amount of movement of each lens group during zooming will increase. Come on. On the other hand, if the value goes below the lower limit, the variable power distribution in the rear group becomes too large, and the amount of movement of each lens group in the rear group increases in order to secure a predetermined variable power ratio, which is not preferable.

Conditional expression (7) relates to the lateral magnification of the fourth lens unit at the wide-angle end. If the upper limit of conditional expression (7) is exceeded, it becomes difficult to obtain back focus at the wide-angle end, resulting in an increase in the lens outer diameter of the fifth lens group. On the other hand, when the value goes below the lower limit, the refractive power of the other lens units becomes strong in order to obtain a constant focal length, so that it becomes difficult to correct aberration variation during zooming. Furthermore, the focal length of the front group must be made longer, which is not good because the total lens length becomes longer.

Preferably, conditional expressions (5), (6),
(7) is preferably in the following range.

0.8 <f3 / fW <1.25 (5 ′) 0.25 <(φ _123W / φ _123T ) / Z <0. 5 ・ ・ ・ ・ ・ ・ (6 ′) 0.2 <β4W <0.4 ・ ・ ・ ・ ・ ・ (7 ′) This makes the lens system compact and good. It is possible to further improve the balance of various optical performances.

Conditional expression (8) is mainly used to properly set the refracting power and lateral magnification of the fifth lens unit to obtain a predetermined back focus. If the upper limit of conditional expression (8) is exceeded, the back focus becomes longer than necessary at the wide-angle end, and the total lens length increases. On the other hand, if the value goes below the lower limit, it becomes difficult to obtain a predetermined back focus at the wide-angle end, and the lens outer diameter of the fifth lens unit increases, which is not good.

(3) The fourth lens unit having a positive refractive power is at least 1
It has a positive lens and a negative lens one by one, of which the lens surface closest to the object side has a concave surface facing the object side, and the lens surface closest to the image surface has a convex surface facing the image surface side. Is good.

(4) When introducing an aspherical surface into the zoom lens of the present invention, for example, by introducing an aspherical surface into the fourth lens unit,
It is possible to easily correct the field curvature at the telephoto end, the aberration of the surface due to the surface aberration and the magnification change, and the aberration correction of the entire screen. In the present invention, the final surface of the fourth group is an aspherical surface. If introduced into the fifth lens unit, mainly off-axis aberrations can be favorably corrected.

(5) The fifth lens unit having negative refractive power has at least 1
When the average values of the Abbe numbers of the materials of the positive lens and the negative lens in the fifth lens group are respectively ν5P and ν5N, each having a negative lens and a positive lens with a concave surface facing the object side, 12 <ν5N -Ν5P <35 It is better to satisfy the condition (9). If the upper limit value or the lower limit value of the conditional expression (9) is exceeded, a large amount of chromatic aberration fluctuations will occur during zooming, and it will be difficult to correct this with other lens groups.

(6) The diaphragm is arranged in an air space existing between the lens surface closest to the image plane of the third lens group to the lens surface closest to the image plane of the fourth lens group, and the entrance pupil is located at an appropriate position. It is preferable because it can be disposed in the optical disk and the variation in aberration due to zooming can be suppressed. The diaphragm may be moved independently of the other lens groups during zooming, or may be moved integrally with the other lens groups. This makes it possible to dispose the diaphragm position in the vicinity of the position of the entrance pupil that moves during zooming, which is advantageous in preventing changes in field curvature aberration when the diaphragm is small.

When focusing is performed by the fourth lens unit, when the fourth lens unit includes an aperture stop, moving the focus lens unit with the aperture stop fixed on the optical axis is a drive for moving the aperture stop mechanism during focusing. It is preferable because the torque can be reduced.

(7) If the fourth group is divided into two or more lens groups and the distance between the lens groups is changed during zooming or during focusing, fluctuations in aberrations during zooming and focusing are reduced. It is possible to do so, which is preferable.

(8) In the present invention, focusing is performed from the object at infinity to the object at a short distance by moving the fourth lens unit toward the object side, but it is also possible to move other lens units. . For example, a method of moving the front group to the object side may be used.

When the back focus is sufficient at the wide-angle end, the fifth lens group may be moved to the image plane side. In this case, it is effective to reduce the lens outer diameter of the first lens group. Becomes It is also possible to simultaneously move two or more lens groups in the first to fifth groups.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number.

Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples.

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive traveling direction of light, and R is a paraxial radius of curvature,
When A, B, C, D and E are aspherical coefficients,

[0055]

[Equation 1] It is expressed by

Numerical Example 1 F = 30.00 to 100.01 fNO = 1: 3.8 to 8.2 2ω = 71.6 ° to 24.4 ° R 1 = −75.51 D 1 = 2.50 N 1 = 1.48749 ν 1 = 70.2 R 2 = -60.06 D 2 = Variable R 3 = -86.13 D 3 = 2.00 N 2 = 1.76182 ν 2 = 26.5 R 4 = -46.48 D 4 = 1.30 N 3 = 1.63854 ν 3 = 55.4 R 5 = 37.68 D 5 = Variable R 6 = 28.74 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 20.87 D 7 = 3.80 N 5 = 1.48749 ν 5 = 70.2 R 8 = -2684.27 D 8 = 0.30 R 9 = 36.29 D 9 = 2.80 N 6 = 1.60311 ν 6 = 60.7 R10 = -217.74 D10 = variable R11 = ∞ (aperture) D11 = 1.50 R12 = -18.69 D12 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R13 = -126.83 D13 = 2.00 R14 = -485.52 D14 = 0.70 N 8 = 1.48749 ν 8 = 70.2 R15 = 45.24 D15 = 1.80 N 9 = 1.84666 ν 9 = 23.8 R16 = -40.48 D16 = 4.97 R17 = 40.96 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 13.82 D18 = 5.90 N11 = 1.58313 ν11 = 59.4 R19 = -23.92 D19 = Variable R20 = -31.77 D20 = 3.20 N12 = 1.84666 ν12 = 23.8 R21 = -19.52 D21 = 0.20 R22 = -23.46 D22 = 1.30 N13 = 1.74320 ν13 = 49.3 R23 = -245.47 D23 = 3.90 R24 = -23.35 D24 = 1.50 N14 = 1.72000 ν14 = 50.3 R25 = -226.34 Aspheric coefficient R19 K = 2.79 A = 0 B = 4.36 × 10 ^-5 C = 3.06 × 10 ^-8 D = 7.74 × 10 ^-10 E = 0

[0057]

[Table 1] (Numerical Example 2) F = 30.00 to 100.00 fNO = 1: 3.7 to 8.2 2ω = 71.6 ° to 24.4 ° R 1 = -156.75 D 1 = 2.50 N 1 = 1.48749 ν 1 = 70.2 R 2 = -61.45 D 2 = Variable R 3 = -76.43 D 3 = 2.00 N 2 = 1.76182 ν 2 = 26.5 R 4 = -43.96 D 4 = 1.30 N 3 = 1.63854 ν 3 = 55.4 R 5 = 36.02 D 5 = Variable R 6 = 28.46 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 20.87 D 7 = 2.80 N 5 = 1.48749 ν 5 = 70.2 R 8 = 2361.46 D 8 = 0.30 R 9 = 34.03 D 9 = 2.00 N 6 = 1.60311 ν 6 = 60.7 R10 = 699.53 D10 = Variable R11 = ∞ (Aperture) D11 = 1.50 R12 = -17.52 D12 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R13 = -114.73 D13 = 2.00 R14 = -358.48 D14 = 0.70 N 8 = 1.48749 ν 8 = 70.2 R15 = 50.31 D15 = 1.80 N 9 = 1.84666 ν 9 = 23.8 R16 = -38.06 D16 = 4.97 R17 = 37.70 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 14.09 D18 = 5.90 N11 = 1.58313 ν11 = 59.4 R19 = -23.75 D19 = Variable R20 = -20.64 D20 = 3.20 N12 = 1.84666 ν12 = 23.8 R21 = -17.20 D21 = 4.00 R22 = -16.56 D22 = 1.70 N13 = 1.77250 ν13 = 49.6 R23 = 253.94 Aspherical coefficient R19 K = 3.13 × 10 ^-1 A = 0 B = 4.79 × 10 ^-5 C = 2.18 × 10 ^-7 D = 1.05 × 10 ^-10 E = 0 Aspherical coefficient R22 K = 0 A = 0 B = 1.69 × 10 ^-5 C = 7.54 × 10 ^-8 D = -9.87 × 10 ^-11 E = 0

[0058]

[Table 2] (Numerical Example 3) F = 35.0 to 106.00 fNO = 1: 3.9 to 7.6 2 ω = 63.4 ° to 23.1 ° R 1 = -79.23 D 1 = 2.50 N 1 = 1.48749 ν 1 = 70.2 R 2 = -53.54 D 2 = Variable R 3 = -62.78 D 3 = 2.00 N 2 = 1.76182 ν 2 = 26.5 R 4 = -39.42 D 4 = 1.30 N 3 = 1.63854 ν 3 = 55.4 R 5 = 36.74 D 5 = Variable R 6 = 30.48 D 6 = 1.00 N 4 = 1.84666 ν 4 = 23.8 R 7 = 22.22 D 7 = 3.80 N 5 = 1.48749 ν 5 = 70.2 R 8 = -240.21 D 8 = 0.30 R 9 = 36.74 D 9 = 2.80 N 6 = 1.60311 ν 6 = 60.7 R10 = -166.62 D10 = Variable R11 = -18.91 D11 = 0.87 N 7 = 1.64769 ν 7 = 33.8 R12 = -123.06 D12 = 1.00 R13 = ∞ (Aperture) D13 = 1.00 R14 = -156.26 D14 = 0.70 N 8 = 1.48749 ν 8 = 70.2 R15 = 42.83 D15 = 1.80 N 9 = 1.84666 ν 9 = 23.8 R16 = -36.50 D16 = 4.97 R17 = 46.04 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 13.31 D18 = 5.90 N11 = 1.58313 ν11 = 59.4 R19 = -27.43 D19 = Variable R20 = -33.93 D20 = 3.20 N12 = 1.84666 ν12 = 23.8 R21 = -19.80 D21 = 0.20 R22 = -23.32 D22 = 1.30 N13 = 1.74320 ν13 = 49.3 R23 = -249.42 D23 = 3.90 R24 = -24.35 D24 = 1.50 N14 = 1.72000 ν14 = 50.3 R25 = -128.73 Aspheric coefficient R19 K = 5.69 × 10 ^-1 A = 0 B = 1.26 × 10 ^-5 C = 1.04 × 10 ^-9 D = -1.93 × 10 ^-9 E = 0

[0059]

[Table 3] (Numerical Example 4) F = 35.00 to 115.28 fNO = 1: 3.9 to 7.9 2ω = 63.4 ° to 21.3 ° R 1 = -118.09 D 1 = 3.00 N 1 = 1.48749 ν 1 = 70.2 R 2 = -60.06 D 2 = Variable R 3 = -58.51 D 3 = 2.40 N 2 = 1.74077 ν 2 = 27.8 R 4 = -61.41 D 4 = 1.50 N 3 = 1.60311 ν 3 = 60.7 R 5 = 38.15 D 5 = Variable R 6 = 34.34 D 6 = 1.20 N 4 = 1.84666 ν 4 = 23.8 R 7 = 27.04 D 7 = 3.20 N 5 = 1.48749 ν 5 = 70.2 R 8 = -319.69 D 8 = 0.15 R 9 = 45.60 D 9 = 2.80 N 6 = 1.65160 ν 6 = 58.5 R10 = -166.18 D10 = Variable R11 = -20.70 D11 = 1.00 N 7 = 1.64769 ν 7 = 33.8 R12 = -62.94 D12 = 1.10 R13 = ∞ (Aperture) D13 = 1.10 R14 = 6539.41 D14 = 0.85 N 8 = 1.48749 ν 8 = 70.2 R15 = 48.84 D15 = 2.18 N 9 = 1.84666 ν 9 = 23.8 R16 = -45.73 D16 = 6.59 R17 = 51.35 D17 = 1.10 N10 = 1.84666 ν10 = 23.8 R18 = 13.56 D18 = 6.00 N11 = 1.58313 ν11 = 59.4 R19 =- 31.86 D19 = Variable R20 = -39.44 D20 = 3.80 N12 = 1.84666 ν12 = 23.8 R21 = -20.59 D21 = 0.15 R22 = -26.82 D22 = 1.40 N13 = 1.74320 ν13 = 49.3 R23 = -184.23 D23 = 3.83 R24 = -25.14 D24 = 1.60 N14 = 1.72000 ν14 = 50.3 R25 = 3454.63 aspheric coefficients ^{R19 K = -1.96 × 10 -1 A} = 0 B = 5.69 ^{10 -6 C = 2.67 × 10 -8} D = -6.80 × 10 -10 E = 0

[0060]

[Table 4] (Numerical Example 5) F = 28.86 to 101.51 FNO = 1: 3.57 to 9.00 2 ω = 73.7 ° to 24.1 ° R 1 = 157.01 D 1 = 3.00 N 1 = 1.51633 ν 1 = 64.2 R 2 = -53.10 D 2 = variable R 3 = -36.16 D 3 = 1.30 N 2 = 1.80400 ν 2 = 46.6 R 4 = 22.09 D 4 = 1.47 R 5 = 23.23 D 5 = 2.50 N 3 = 1.84665 ν 3 = 23.8 R 6 = 111.27 D 6 = variable R 7 = 14.89 D 7 = 0.90 N 4 = 1.84665 ν 4 = 23.8 R 8 = 10.80 D 8 = 4.10 N 5 = 1.49699 ν 5 = 81.6 R 9 = -48.02 D 9 = Variable R10 = ∞ (diaphragm) D10 = 1.30 R11 = -23.66 D11 = 3.42 N 6 = 1.80518 ν 6 = 25.4 R12 = -49.46 D12 = 0.91 R13 = -39.81 D13 = 1.00 N 7 = 1.65159 ν 7 = 58.5 R14 = 120.33 D14 = 3.70 N 8 = 1.77249 ν 8 = 49.6 R15 = -14.40 D15 = Variable R16 = -25.86 D16 = 2.30 N 9 = 1.84665 ν 9 = 23.8 R17 = -19.73 D17 = 0.30 R18 = -26.17 D18 = 1.30 N10 = 1.69679 ν10 = 55.5 R19 = -71.00 D19 = 3.04 R20 = -18.67 D20 = 1.50 N11 = 1.77249 ν11 = 49.6 R21 = -1220.31 Aspheric coefficient R11 K = 5.04 A = 0 B = -4.96 × 10 ^-5 C = -1.08 × 10 ^-7 D = -1.67 × 10 ^-9 E = 0 Aspherical coefficient R15 K = -2.77 A = 0 B = -1.10 × 10 ^-4 C = 1.43 × 10 ^-7 D = 1.38 × 10 ^-10 E = 0

[0061]

[Table 5] (Numerical Example 6) F = 28.80 to 10.913 FNO = 1: 4.20 to 9.00 2ω = 73.8 ° to 24.0 ° R 1 = 261.44 D 1 = 2.40 N 1 = 1.51633 ν 1 = 64.2 R 2 = -50.37 D 2 = variable R 3 = -34.45 D 3 = 1.20 N 2 = 1.80400 ν 2 = 46.6 R 4 = 19.52 D 4 = 1.35 R 5 = 21.12 D 5 = 2.90 N 3 = 1.84665 ν 3 = 23.8 R 6 = 153.65 D 6 = Variable R 7 = 15.59 D 7 = 0.90 N 4 = 1.84665 ν 4 = 23.8 R 8 = 11.39 D 8 = 4.50 N 5 = 1.48749 ν 5 = 70.2 R 9 = -20.96 D 9 = 0.90 N 6 = 1.84665 ν 6 = 23.8 R10 = -29.92 D10 = 0.80 R11 = ∞ (Aperture) D11 = Variable R12 = -24.41 D12 = 2.48 N 7 = 1.80518 ν 7 = 25.4 R13 = -46.79 D13 = 0.23 R14 = -39.64 D14 = 1.00 N 8 = 1.65159 ν 8 = 58.5 R15 = 137.86 D15 = 5.80 N 9 = 1.77249 ν 9 = 49.6 R16 = -14.51 D16 = variable R17 = -28.30 D17 = 2.30 N10 = 1.84665 ν10 = 23.8 R18 = -19.96 D18 = 0.30 R19 = -25.92 D19 = 1.30 N11 = 1.69679 ν11 = 55.5 R20 = -87.84 D20 = 3.58 R21 = -18.45 D21 = 1.50 N12 = 1.77249 ν12 = 49.6 R22 = 320.35 Aspheric surface coefficient R12 K = 5.02 A = 0 B = -6.76 × 10 ^-5 C = -3.34 × 10 ^-7 D = -5.05 × 10 ^-9 E = 0 Aspheric surface coefficient R16 K = -2.65 A = 0 B = -1.12 × 10 ^-4 C = 1.24 × 10 ^-7 D = -1.10 × 10 ^-9 E = 0

[0062]

[Table 6]

[0063]

As described above, according to the present invention, as a whole, it is composed of five lens groups, and by appropriately setting the moving conditions and the refractive power of each lens group during zooming, photographing at the wide-angle end is possible. It is possible to achieve a zoom lens having a high optical performance over the entire zoom range with an angle of view of about 64 to 72 degrees and a zoom ratio of about 3.5.

[Brief description of drawings]

FIG. 1 is an explanatory view of a paraxial refractive power arrangement of a zoom lens according to the present invention.

FIG. 2 is a lens cross-sectional view at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 3 is a lens cross-sectional view at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 4 is a lens cross-sectional view at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 5 is a lens cross-sectional view at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 6 is a lens cross-sectional view at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 7 is a lens cross-sectional view at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 8 is an aberration diagram at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 9 is an intermediate aberration diagram of Numerical Example 1 of the present invention.

FIG. 10 is an aberration diagram at a telephoto end according to Numerical Example 1 of the present invention.

FIG. 11 is an aberration diagram at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 12 is an intermediate aberration diagram of Numerical example 2 of the present invention.

FIG. 13 is an aberration diagram at a telephoto end according to Numerical Example 2 of the present invention.

FIG. 14 is an aberration diagram at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 15 is an intermediate aberration diagram of Numerical example 3 of the present invention.

FIG. 16 is an aberration diagram at a telephoto end according to Numerical Example 3 of the present invention.

FIG. 17 is an aberration diagram at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 18 is an intermediate aberration diagram of Numerical example 4 of the present invention.

FIG. 19 is an aberration diagram at a telephoto end according to Numerical Example 4 of the present invention.

FIG. 20 is an aberration diagram at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 21 is an intermediate aberration diagram of Numerical Example 5 of the present invention.

FIG. 22 is an aberration diagram at a telephoto end according to Numerical Example 5 of the present invention.

FIG. 23 is an aberration diagram at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 24 is an intermediate aberration diagram of Numerical Example 6 of the present invention.

FIG. 25 is an aberration diagram at a telephoto end according to Numerical Example 6 of the present invention.

[Explanation of symbols]

 L1 1st group L2 2nd group L3 3rd group L4 4th group L5 5th group SP diaphragm IP image surface d d line g g line S. C Sine condition ΔS Sagittal image plane ΔM Meridional image plane

Claims (3)

[Claims] 1. A composite refracting power at a wide-angle end, comprising three lens groups, a first group having a positive refracting power, a second group having a negative refracting power, and a third group having a positive refracting power in order from the object side. Has a front lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a rear lens group consisting of a fifth lens group having a negative refractive power, and at the time of zooming from the wide-angle end to the telephoto end. , The first, second, and third groups move so that the combined refractive power of the front group becomes weaker at the telephoto end than at the wide-angle end, and the fourth and fifth groups move so that their interval becomes narrower. The focal length of the i-th group is fi, the focal length of the entire system at the wide-angle end is fW, and the lateral magnification of the i-th group at the wide-angle end is βi.
A zoom lens characterized by satisfying the following conditions: 0.45 <| f5 / fW | <1.5 1.1 <β5W <1.9. 2. When zooming from the wide-angle end to the telephoto end, the first, second, and third groups are all closer to the object side, and the distance between the first group and the second group is increased, and the second group is increased. The zoom lens according to claim 1, wherein the zoom lens is moved so that the distance between the third lens group and the third lens group is reduced. 3. When the combined refractive power of the front group at the wide-angle end is φ _123W , the condition of 0.3 <fW · φ _123W <1.2 0.6 <| f2 / fW | <3.0 is satisfied. The zoom lens according to claim 2, wherein