JP2006079004A - Zoom lens, camera, and personal digital assistant device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zoom lens which has a wide viewing angle of the wide angle end, is small-sized and bright, moreover, requires only a small number of lenses and is low-cost by using a composition of at least four groups of positive-negative-positive-positive. <P>SOLUTION: The zoom lens is constituted by arranging a first group optical system G1 having a positive focal distance, a second group optical system G2 having a negative focal distance, a third group optical system G3 having a positive focal distance, and a fourth group optical system G4 having a positive focal distance in order from the object side. The first group optical system G1 is composed of a positive lens L1. Upon the zooming, the first group optical system G1, the third group optical system G3 and the fourth group optical system G4 are moved on the optical axis in accordance with variable power from the short focus wide-angle end to the long focus telephoto end, however the second group optical system G2 is fixedly arranged for the image surface and is not moved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a zoom lens in which a focal length is changed by advancing and retracting a plurality of lens groups individually in the optical axis direction, and more particularly, a camera using electronic imaging means such as a digital camera and a digital video camera. The present invention relates to a zoom lens suitable for a wide angle, a camera using such a zoom lens, and a portable information terminal device.

In recent years, a wide-angle state where the focal length of the taking lens is short and a wide angle of view can be obtained, and a telephoto state where the focal length is long and the angle of view is narrow, between the wide-angle end with the shortest focal length and the telephoto end with the longest focal length. Digital cameras equipped with a variable focus mechanism such as a zoom lens barrel that can be selectively switched are widely used.
There are a wide variety of user needs for digital cameras equipped with this type of variable focus mechanism, and among them, the need for higher image quality and smaller size is particularly high. Therefore, a zoom lens used as a photographing lens is also required to achieve both high performance and downsizing.
Here, in terms of miniaturization, first, it is necessary to shorten the entire lens length (the distance from the lens surface closest to the object side to the image plane). Furthermore, in terms of high performance, it is necessary to have a resolving power corresponding to an image sensor with at least 3 to 5 million pixels over the entire zoom range. In addition, there are many users who desire a wide angle of view of the photographing lens, and it is desirable that the half angle of view at the wide angle end of the zoom lens is 42 degrees or more. A half angle of view of 42 degrees corresponds to a focal length in terms of a 35 mm silver salt camera (so-called Leica version) of 24 mm.

  In the conventional zoom lens in this field, examples of those that have been reduced in size for consumer use include, for example, those disclosed in Patent Document 1 (Patent No. 2920549) and Patent Document 2 (Patent No. 3091250). Has been proposed. In these Patent Documents 1 and 2, the first group optical system having a positive refractive power and a fixed position at the time of zooming and a negative refractive power in order from the object side to the image surface side. A second optical system that moves from the object side to the image plane side from the wide-angle end to the telephoto end during zooming, and has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end during zooming. A zoom lens with a positive-negative-positive-positive four-group zoom configured by arranging a third group optical system and a fourth group optical system having positive refractive power and fixed position at the time of zooming is shown. ing. However, the zoom lenses of Patent Document 1 and Patent Document 2 both have a half angle of view of less than 25 degrees, and are not sufficient in terms of widening the angle.

Further, for example, Patent Document 3 (JP-A-6-94997), Patent Document 4 (JP-A-10-62687) and Patent Document 5 (JP-A-11-258507) disclose a fourth group optical system. The zoom lens is operated at the time of zooming, and more advanced aberration correction is performed to further reduce the size and widen the angle. Although all the basic configurations of Patent Document 3 are disclosed, they are not sufficient in terms of miniaturization. Although the thing of patent document 4 aims at size reduction by reducing the number of lens composition, sufficient aberration correction is not performed, and it has the performance which can respond to an image sensor of 3-5 million pixels. Not. Further, the one of Patent Document 5 is relatively small, and the image performance is better than that described above, but the half angle of view is only about 33 degrees, which is still not sufficient in terms of widening the angle. I can't say that.
Further, as positive-negative-positive-positive four-group zooms in which the first group optical system is composed of one positive lens, for example, those shown in Patent Literature 6, Patent Literature 7, Patent Literature 8, and Patent Literature 9 Etc. have been proposed. However, these Patent Documents 6 to 9 do not show a configuration that achieves both wide angle and downsizing.

Japanese Patent No. 2920549 Japanese Patent No. 3091250 JP-A-6-94997 JP-A-10-62687 Japanese Patent Laid-Open No. 11-258507 JP 2001-042215 A JP 2001-194586 A JP 2001-242379 A JP 2001-356269 A

As described above, both of Patent Document 1 and Patent Document 2 have a half angle of view of less than 25 degrees, which is insufficient in terms of widening the angle. In terms of surface, the configuration is inadequate. Patent Document 4 does not have sufficient aberration correction, and does not have performance capable of handling an image sensor with 3 to 5 million pixels. The half angle of view is about 33 degrees, which is insufficient in terms of widening the angle, and Patent Documents 6 to 9 do not show a configuration that achieves both widening and miniaturization.
Accordingly, the present invention has been made in view of the above-described circumstances, and in order from the object side, a first group optical system having a positive focal length, a second group optical system having a negative focal length, and a positive In a zoom lens using a configuration of four or more positive-negative-positive-positive groups including a third group optical system having a focal length of 4 mm and a fourth group optical system having a positive focal length, An object of the present invention is to provide a low-cost zoom lens that is small, bright, and has a small number of required lenses, and a camera and a portable information terminal device using such a zoom lens.

An object of claim 1 of the present invention is a zoom lens that can achieve a high performance with a resolution that corresponds to an image sensor with 3 million to 5 million pixels or more, in particular, while obtaining a small and sufficient wide angle of view. Is to provide.
A second object of the present invention is to provide a zoom lens capable of obtaining a particularly wide angle of view.
A third object of the present invention is to provide a zoom lens that can reduce the overall length of the lens to achieve downsizing, can be easily assembled, and can reduce aberration fluctuation during zooming.
A fourth object of the present invention is to provide a zoom lens that can correct the lateral chromatic aberration satisfactorily and obtain higher performance.
An object of claim 5 of the present invention is to provide a zoom lens that can efficiently correct distortion, field curvature, and astigmatism mainly on the wide-angle side and obtain higher performance. It is in.
An object of claim 6 of the present invention is to provide a zoom lens that can achieve a wider angle of view mainly by effectively manipulating the light path.

The object of claim 7 of the present invention is that it is possible to satisfactorily correct spherical aberration on the telephoto side even with a zoom lens having a large zoom ratio, to easily correct lateral chromatic aberration, and to achieve performance by decentration. An object of the present invention is to provide a zoom lens capable of suppressing deterioration and obtaining higher performance.
The object of claim 8 of the present invention is to allow the light emitted from the third group optical system, which changes with zooming, to enter the fourth group optical system at a desired angle. It is an object of the present invention to provide a zoom lens that can be obtained.
The object of claim 9 of the present invention is to increase the focusing speed and to achieve higher performance by using the fourth group optical system as a focus group in order to reduce the weight by using a small number of lenses. It is an object of the present invention to provide a zoom lens that can be obtained.
The object of claim 10 of the present invention is to provide a camera that can achieve a high performance with a resolution that corresponds to an image sensor with 3 million to 5 million pixels or more, in particular, while obtaining a small and sufficient wide angle of view. It is to provide.
The object of claim 11 of the present invention is, in particular, portable information that can achieve a high performance with a small size and a sufficiently wide angle of view and a resolving power corresponding to an image sensor of 3 to 5 million pixels or more. It is to provide a terminal device.

In order to achieve the above object, a zoom lens according to the present invention described in claim 1 is provided.
The first group optical system having a positive focal length, the second group optical system having a negative focal length, the third group optical system having a positive focal length, and the positive focal length in order from the object side In a zoom lens comprising a fourth group optical system having
The first group optical system is composed of a single positive lens, and the first group optical system, the third group optical system, and the fourth group accompanying zooming from the short focus wide angle end to the long focus telephoto end. The optical system moves on the optical axis, and the second group optical system is fixedly arranged with respect to the image plane.
A zoom lens according to the present invention described in claim 2 is the zoom lens according to claim 1,
The focal length of the short focal wide angle end is fw, the maximum image height of the image to be formed is h,
Conditional expression:
35 <tan ⁻¹ (fw / h)
It is characterized by satisfying.

The zoom lens according to the present invention described in claim 3 is the zoom lens according to claim 1 or 2,
If the focal length of the i-th group optical system (i = 1 to 3) is fi,
Conditional expression:
0.6 <| f2 | / f3 <0.8
It is characterized by satisfying.
The zoom lens according to a fourth aspect of the present invention is the zoom lens according to any one of the first to third aspects,
The positive lens constituting the first group optical system has a refractive index Nd and an Abbe number νd.
Conditional expression:
Nd> 1.55
νd> 55
It is characterized by being formed of a glass material that satisfies the above.

A zoom lens according to a fifth aspect of the present invention is the zoom lens according to any one of the first to fourth aspects,
The optical surface on the most object side of the second group optical system is configured as an aspherical surface.
The zoom lens according to the present invention described in claim 6 is the zoom lens according to claim 5,
The optical surface on the most object side of the first group optical system is configured as an aspherical surface.
The zoom lens according to the present invention described in claim 7 is the zoom lens according to any one of claims 1 to 6,
The third group optical system includes a cemented lens.
The zoom lens according to the present invention described in claim 8 is the zoom lens according to any one of claims 1 to 7,
The optical surface closest to the image side of the third group optical system is configured as an aspherical surface.

The zoom lens according to the present invention described in claim 9 is the zoom lens according to any one of claims 1 to 8,
The fourth group optical system is characterized in that focusing is performed by movement in the optical axis direction.
A camera according to a tenth aspect of the present invention includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system.
The portable information terminal device according to the present invention described in claim 11 has a camera function unit, and as a photographing optical system of the camera function unit, any one of claims 1 to 9. It is characterized by comprising a zoom lens.

According to the present invention, the first group optical system having a positive focal length, the second group optical system having a negative focal length, and the third group optical system having a positive focal length sequentially from the object side. In a zoom lens using a positive-negative-positive-positive four-group or more configuration in which a fourth group optical system having a positive focal length is arranged, the zoom lens has a wide angle of view at the wide-angle end, It is possible to provide a small, bright and low-cost zoom lens with a small number of required lenses, and a camera and a portable information terminal device using such a zoom lens.
That is, according to the zoom lens of the first aspect of the present invention, the first group optical system having the positive focal length, the second group optical system having the negative focal length, and the positive focal length sequentially from the object side. And a fourth lens group optical system having a positive focal length, the first lens group optical system is composed of a single positive lens and has a short focal length. The first group optical system, the third group optical system, and the fourth group optical system move on the optical axis in accordance with zooming from the wide-angle end to the long focal length telephoto end, and the second group optical system By being fixedly arranged with respect to the surface, in particular, a small size and a sufficiently wide angle of view can be obtained, and a high performance can be realized with a resolving power corresponding to an image sensor with 3 to 5 million pixels or more. be able to.

According to the zoom lens of claim 2 of the present invention, in the zoom lens of claim 1, the focal length of the short focal wide angle end is fw, and the maximum image height of the image to be formed is h.
Conditional expression:
35 <tan ⁻¹ (fw / h)
By satisfying the above, it is possible to obtain a particularly wide angle of view.
According to the zoom lens of claim 3 of the present invention, the zoom lens of claim 1 or claim 2, wherein the focal length of the i-th group optical system (i = 1 to 3) is fi,
Conditional expression:
0.6 <| f2 | / f3 <0.8
By satisfying the above, in particular, it is possible to reduce the overall length of the lens to achieve miniaturization, as well as to easily assemble, and to reduce aberration fluctuations during zooming.

According to a zoom lens of a fourth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the positive lens constituting the first group optical system has a refractive index Nd. And the Abbe number νd,
Conditional expression:
Nd> 1.55
νd> 55
In particular, it is possible to obtain a higher performance by correcting the lateral chromatic aberration satisfactorily.
According to a zoom lens of a fifth aspect of the present invention, the zoom lens according to any one of the first to fourth aspects, wherein an optical surface closest to the object side of the second group optical system is configured as an aspherical surface. This makes it possible to efficiently correct distortion, field curvature, and astigmatism mainly on the wide-angle side, thereby obtaining higher performance.
According to a zoom lens of a sixth aspect of the present invention, in the zoom lens according to the fifth aspect of the invention, the optical surface closest to the object side of the first optical system is an aspherical surface, and in particular, mainly the light path. It is possible to achieve a wider angle of view by operating effectively.

According to the zoom lens of claim 7 of the present invention, the zoom lens according to any one of claims 1 to 6, wherein the third group optical system includes a cemented lens. Even a zoom lens with a large zoom ratio can correct spherical aberration on the telephoto side well, easily correct lateral chromatic aberration, and suppress performance deterioration due to decentration to obtain higher performance. Is possible.
According to a zoom lens of an eighth aspect of the present invention, in the zoom lens according to any one of the first to seventh aspects, an optical surface closest to the image side of the third group optical system is an aspherical surface. In particular, the light emitted from the third group optical system that changes with zooming can be incident on the fourth group optical system at a desired angle, and higher performance can be obtained. Become.
According to a zoom lens of a ninth aspect of the present invention, the zoom lens according to any one of the first to eighth aspects, wherein focusing is performed by movement of the fourth group optical system in the optical axis direction. In particular, by configuring the fourth group optical system with a small number of sheets to reduce the weight and using the fourth group optical system as a focus group, it is possible to improve the focusing speed and obtain higher performance.

According to the camera of claim 10 of the present invention, the zoom lens according to any one of claims 1 to 9 is included as the photographing optical system, so that it is particularly small and sufficient. In addition to obtaining a wide angle of view, it is possible to achieve high performance with the resolving power corresponding to an image sensor with 3 to 5 million pixels or more.
According to the portable information terminal device of the eleventh aspect of the present invention, the portable information terminal device according to any one of the first to ninth aspects has a camera function section and the photographing optical system of the camera function section. By including the zoom lens, in particular, a small size and a sufficiently wide angle of view can be obtained, and a high performance can be realized with a resolving power corresponding to an image sensor with 3 to 5 million pixels or more.

[First Embodiment]
Hereinafter, a first embodiment of a zoom lens according to the present invention will be described in detail with reference to the drawings. Before describing specific examples, first, in order to explain the principle embodiments of the present invention, configurations and functions defined in the claims of the claims will be described.
A zoom lens according to claims 1 to 9 of the present invention includes, from the object side, a first group optical system having a positive focal length, a second group optical system having a negative focal length, and a positive The zoom lens includes a third group optical system having a focal length and a fourth group optical system having a positive focal length. The zoom lens further has the following characteristics.
In the zoom lens according to claim 1, the first group optical system includes a single positive lens, and the first group optical system in accordance with zooming from a short focal wide angle end to a long focal telephoto end, The third group optical system and the fourth group optical system move on the optical axis, and the second group optical system is fixedly arranged with respect to the image plane.

The zoom lens according to a second aspect satisfies the following conditional expression in the zoom lens according to the first aspect.
35 <tan ⁻¹ (fw / h)
Where fw is the focal length at the wide-angle end, and h is the maximum image height of the image to be formed. This conditional expression means the angle of view at the wide-angle end of the zoom lens of the present invention, and the angle of view becomes narrow outside the range of the conditional expression.
The zoom lens according to a third aspect of the present invention satisfies the following conditional expression in the zoom lens of the first or second aspect.
0.6 <| f2 | / f3 <0.8
Here, fi is the focal length of the i-th lens group (i = 1 to 3). By this conditional expression, in the zoom lens configuration of the present invention, the ratio of the refractive powers of the second group optical system and the third group optical system responsible for the main zooming action is defined. If the upper limit of the conditional expression is exceeded, the negative refractive power of the second group optical system becomes small and the refractive power of the third group optical system also becomes small, so that the total lens length becomes long. If the lower limit of the conditional expression is exceeded, the negative refractive power of the second group optical system increases, so that high assembly accuracy is required, and aberration fluctuation during zooming increases.

  A zoom lens according to a fourth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the positive lens constituting the first group optical system satisfies the following conditional expression: It is a glass material having Nd and Abbe number νd.

Nd> 1.55
νd> 55
These are conditional expressions for satisfactorily correcting the chromatic aberration of magnification occurring in the zoom lens of the present invention having a large zoom ratio. Outside the given range, the chromatic aberration of magnification at the periphery of the screen is large over the entire zoom range. Will adversely affect the image.
The zoom lens according to a fifth aspect is the zoom lens according to any one of the first to fourth aspects, wherein the most object side surface of the second group optical system is an aspherical surface. By making the most object side surface of the second group optical system an aspherical surface, it becomes possible to efficiently correct distortion, curvature of field and astigmatism on the wide angle side. Various aberrations such as distortion, curvature of field and astigmatism are corrected by making the ray path effective by aspherical the surface through which the principal ray of the ray bundle incident from outside the optical axis passes far away from the optical axis. Can be operated manually.

As an aspheric lens, optical glass and optical plastic are molded (referred to as glass mold aspheric surface and plastic mold aspheric surface, respectively), or a thin resin layer is molded on the surface of the glass lens. An aspherical surface (referred to as a hybrid aspherical surface or a replica aspherical surface) can be used.
The zoom lens according to a sixth aspect is the zoom lens according to the fifth aspect, wherein the most object-side surface of the first group optical system is an aspherical surface. In order to achieve a wide angle of view when the first group optical system is composed of a single lens, a desired incident angle corresponding to the light beam angle is formed by an aspherical surface, thereby effectively manipulating the light beam path. be able to.
Also in this case, as the aspherical lens, one obtained by molding optical glass and optical plastic, or one obtained by molding a thin resin layer on the surface of the glass lens and making the surface an aspherical surface can be used.
A zoom lens according to a seventh aspect is the zoom lens according to any one of the first to sixth aspects, wherein a cemented lens is included in the third group optical system. By disposing at least one cemented lens in the third group optical system, it is possible to satisfactorily correct spherical aberration on the telephoto side even in the zoom lens of the present invention having a large zoom ratio, and at the same time correct lateral chromatic aberration. Will also be easier. In addition, performance degradation due to eccentricity can be suppressed.

A zoom lens according to an eighth aspect is the zoom lens according to any one of the first to seventh aspects, wherein the most image side surface of the third group optical system is an aspherical surface. By making the most image side surface of the third group optical system an aspherical surface, the emitted light from the third group optical system, which changes with zooming, is transmitted to the fourth group optical system at a desired angle. It has a function to make it incident.
After all, as the aspherical lens, it is possible to use an optical glass and optical plastic molded one, or a thin resin layer formed on the surface of the glass lens and the surface thereof is aspherical.
A zoom lens according to a ninth aspect is the zoom lens according to any one of the first to eighth aspects, wherein the fourth group optical system performs focusing, that is, focus adjustment (so-called focusing). That is, during the focusing operation, the fourth group optical system is moved along the optical axis. In this case, since the electronic imaging device is mainly targeted for the imaging plane, it is desirable that the light incident on the imaging plane is parallel light. By arranging the fourth group optical system having a positive refractive power in the vicinity of the image forming surface, this condition can be easily achieved, and the fourth group optical system plays a role in adjusting the aberration of the entire zoom lens. Is responsible. By configuring the fourth group optical system with a small number of sheets to reduce the weight and using the fourth group optical system as a focus group (focusing group), it is possible to improve the focusing speed. At this time, in order to obtain good photographing performance with a small number of lenses from infinity to a short distance, it is desirable to increase the degree of freedom of aberration correction by using at least one aspherical surface for this focus group.

A camera according to a tenth aspect includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system. If the camera is configured using the zoom lens according to any one of claims 1 to 9 as a photographing optical system, a small and sufficient wide angle of view can be obtained. It is possible to achieve high performance with the resolving power corresponding to an image sensor with 10,000 pixels or more.
A portable information terminal device according to an eleventh aspect includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system of a camera function unit. If a portable information terminal device is configured using the zoom lens according to any one of claims 1 to 9 as a photographing optical system of a camera function unit, a small and sufficient wide angle of view can be obtained. Therefore, it is possible to achieve high performance with the resolving power corresponding to an image sensor with 3 to 5 million pixels or more.

Next, specific examples based on the above-described embodiment of the present invention will be described in detail. Example 1, Example 2, Example 3, and Example 4 described below are examples of specific configurations based on specific numerical examples of the zoom lens according to the present invention, and other embodiments are examples. 1 is a specific embodiment of a camera or a portable information terminal device according to the present invention using a zoom lens as shown in Examples 1 to 4 as a photographing optical system.
In the first to fourth embodiments of the zoom lens according to the present invention, the configuration of the zoom lens and specific numerical examples thereof are shown.
In the first to fourth embodiments, the optical element formed of a parallel plate disposed on the image side of the fourth group optical system includes various optical filters such as an optical low-pass filter and an infrared cut filter, and light reception by a CCD image sensor and the like. It is a cover glass (seal glass) of the element.
In Examples 1 and 4, both the most object-side surface and the most image-side surface of the second group optical system and the most object-side surface and the most image-side surface of the third group optical system are used. Both are aspherical surfaces. In Example 2, both the most object-side surface of the first group optical system, the most object-side surface and the most image-side surface of the second group optical system, and the most object of the third group optical system The side surface and the object side surface of the most image side lens of the third group optical system are aspherical surfaces.

Further, in Example 3, both the most object side surface and the most image side surface of the second group optical system, the most object side surface of the third group optical system, and the most image side of the third group optical system are used. Each of the lenses has an aspheric surface on the object side. In addition, the aspherical surface in Example 1 to Example 4 is obtained by laying a resin thin film that forms an aspherical surface on the lens surface of the spherical lens only on the most object side surface of the second group optical system to obtain an aspherical surface. A so-called hybrid lens type aspherical lens is used. In other cases, an equivalent aspherical surface is formed as a so-called molded aspherical lens in which each lens surface is directly aspherical by molding.
The aberration in Examples 1 to 4 is sufficiently corrected, and can correspond to a light receiving element having 3 to 5 million pixels. It is apparent from Examples 1 to 4 that by configuring the zoom lens according to the present invention, very good image performance can be ensured while achieving a sufficiently small size and wide angle.
The meanings of the symbols in Examples 1 to 4 are as follows.

f: the focal length F of the entire system: F number omega: half field angle R: curvature radius D: surface interval Nd: refractive index [nu] d: Abbe number K: aspherical conic constant A _4: 4-order aspheric coefficient A ₆ : 6th-order aspheric coefficient A ₈ : 8th-order aspheric coefficient A ₁₀ : 10th-order aspheric coefficient However, the aspheric surface used here is the reciprocal of the paraxial radius of curvature (paraxial curvature) C, light When the height from the axis is H, it is defined by the following equation.

図１は、本発明の実施例１に係るズームレンズの光学系の短焦点広角端の状態における構成および変倍時の各群光学系の移動軌跡を示している。
図１に示すズームレンズは、第１レンズＬ１、第２レンズＬ２、第３レンズＬ３、第４レンズＬ４、第５レンズＬ５、第６レンズＬ６、第７レンズＬ７、第８レンズＬ８、第９レンズＬ９、絞りＦＡ、第１フィルタＯＦ１、第２フィルタＯＦ２およびカバーガラスＣＧを具備している。この場合、第１レンズＬ１は、単体で第１群光学系Ｇ１を構成し、第２レンズＬ２〜第４レンズＬ４は、第２群光学系Ｇ２を構成し、第５レンズＬ５〜第８レンズＬ８は、第３群光学系Ｇ３を構成し、そして第９レンズＬ９は、単体で第４群光学系Ｇ４を構成しており、それぞれ各群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各群毎に一体的に動作する。図１には、各光学面の面番号も示している。なお、図１に対する各参照符号は、参照符号の桁数の増大による説明の煩雑化を避けるため、各実施例毎に独立に用いており、そのため図２〜図４と共通の参照符号を付していてもそれらは他の実施例とはかならずしも共通の構成ではない。

FIG. 1 shows the configuration of the optical system of the zoom lens according to Embodiment 1 of the present invention at the short focal wide angle end and the movement trajectory of each group optical system during zooming.
The zoom lens shown in FIG. 1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens. A lens L9, an aperture FA, a first filter OF1, a second filter OF2, and a cover glass CG are provided. In this case, the first lens L1 alone constitutes the first group optical system G1, the second lens L2 to the fourth lens L4 constitute the second group optical system G2, and the fifth lens L5 to the eighth lens. L8 constitutes a third group optical system G3, and the ninth lens L9 constitutes a fourth group optical system G4 as a single unit, and is supported by a common support frame or the like appropriate for each group, When zooming or the like, each group operates integrally. FIG. 1 also shows the surface numbers of the optical surfaces. 1 are used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, the same reference numerals as those in FIGS. However, they are not necessarily in common with other embodiments.

In FIG. 1, each optical element constituting the optical system of the zoom lens includes, for example, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture FA, sequentially from the object side such as a subject. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the first filter OF1, the second filter OF2, and the cover glass CG are arranged in this order. It is imaged behind.
The first lens L1 is a positive meniscus lens that is convexly formed on the object side. Of course, the first group optical system G1 constituted solely by the first lens L1 has a positive focal length. The second lens L2 is a negative meniscus lens convexly formed on the object side, and a hybrid aspherical surface (surface number 3) is formed by laying a resin layer on the object-side surface (surface number 4). Yes. The third lens L3 is a negative lens composed of a biconcave lens, and the fourth lens L4 is a positive meniscus lens formed convex on the object side, and an aspheric surface is provided on the image side surface (surface number 8) of the fourth lens L4. Forming. The third lens L3 and the fourth lens L4 are closely bonded and joined together to form a cemented lens. The second group optical system G2 configured by the second lens L2 to the fourth lens L4 has a negative focal length, that is, negative refractive power as a whole. The fifth lens L5 is a positive meniscus lens formed convex on the object side, and an aspherical surface is formed on the object side surface (surface number 10) of the fifth lens L5. The sixth lens L6 is a positive lens composed of a biconvex lens with a strong convex surface facing the image side, and the seventh lens L7 is a negative lens composed of a biconcave lens.

The eighth lens L8 is a positive lens composed of a biconvex lens having a strong convex surface facing the object side, and an aspherical surface is formed on the image side surface (surface number 17) of the eighth lens L8. The third group optical system G3 configured by the fifth lens L5 to the eighth lens L84 has a positive focal length (positive refractive power) as a whole. The ninth lens L9 is a positive lens composed of a plano-convex lens having a convex surface facing the object side. The fourth group optical system G4 constituted solely by the ninth lens L9 naturally has a positive focal length.
In zooming between the short focal wide angle end and the long focal telephoto end, the variable distance between each group and the aperture stop FA, that is, the most image side surface of the first group optical system G1, that is, the first The distance d1 between the image side surface (surface number 2) of the lens L1 and the most object side surface of the second group optical system G2, that is, the object side surface (surface number 3) of the second lens L2, the second group The distance d2 between the most image-side surface of the optical system G2, that is, the image-side surface (surface number 8) of the fourth lens L4, and the surface of the stop FA (surface number 9), and the surface of the stop FA (surface number 9) And the distance d3 between the most object side surface of the third group optical system G3, that is, the object side surface (surface number 10) of the fifth lens L5, and the most image side surface of the third group optical system G3, ie, the first surface. The image side surface (surface number 17) of the eight lens L8 and the most object side surface of the fourth group optical system G4, that is, the object side surface (surface number 1) of the ninth lens L9. ) And the interval d4 changes of.

At the time of zooming from the short focus end to the long focus end, the second group optical system G2 holds the position in a fixed manner, and with the zooming from the short focus end to the long focus end, the first group optical system G1 moves monotonously toward the object side, the aperture FA monotonously moves toward the object side, the third group optical system G3 moves monotonously toward the object side, and the fourth group optical system G4 At least the first group optical system G1, the third group optical system G3, the stop FA, and the fourth group optical system G4 move so as to move monotonously toward the image side.
In the first embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.14 to 17.216, F = 2.13 to 3.13, ω = It changes in the range of 43.16-14.73. The characteristics of each optical surface are as shown in the following table.

  In Table 1, the optical surfaces of the third surface, the eighth surface, the tenth surface, and the seventeenth surface indicated by adding “* (asterisk)” to the surface number are aspherical surfaces. The parameters in the formula are as follows.

  The variable distance d1 between the first group optical system G1 and the second group optical system G2, the variable distance d2 between the second group optical system G2 and the stop FA, and between the stop FA and the third group optical system G3 The variable interval d3 and the variable interval d4 between the third group optical system G3 and the fourth group optical system G4 are changed as shown in the following table with zooming.

Further, the parameter values according to the conditional expressions described in the first embodiment are as follows.
Conditional parameter value:
tan ⁻¹ (fw / h) = 42.19
| F2 | /f3=0.784
Therefore, the parameter values related to the conditional expression described in the first embodiment are within the range of the conditional expression.

FIG. 2 shows the configuration of the optical system of the zoom lens according to Embodiment 2 of the present invention at the short focal wide angle end and the movement trajectory of each group optical system at the time of zooming.
The zoom lens shown in FIG. 2 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens. A lens L9, an aperture FA, a first filter OF1, a second filter OF2, and a cover glass CG are provided. In this case, the first lens L1 alone constitutes the first group optical system G1, the second lens L2 to the fourth lens L4 constitute the second group optical system G2, and the fifth lens L5 to the eighth lens. L8 constitutes a third group optical system G3, and the ninth lens L9 constitutes a fourth group optical system G4 as a single unit, and is supported by a common support frame or the like appropriate for each group, When zooming or the like, each group operates integrally. FIG. 2 also shows the surface numbers of the optical surfaces. 2 are used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, the same reference numerals as those in FIGS. 1, 3, and 4 are used. Even if the reference numerals are given, they are not necessarily in common with the other embodiments.

In FIG. 2, each optical element constituting the optical system of the zoom lens includes, for example, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture FA, sequentially from the object side such as a subject. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the first filter OF1, the second filter OF2, and the cover glass CG are arranged in this order. It is imaged behind.
The first lens L1 is a positive meniscus lens convexly formed on the object side, and an aspherical surface is formed on the object side surface (surface number 1) of the first lens L1. Of course, the first group optical system G1 constituted solely by the first lens L1 has a positive focal length. The second lens L2 is a negative meniscus lens convexly formed on the object side, and a hybrid aspherical surface (surface number 3) is formed by laying a resin layer on the object-side surface (surface number 4). Yes. The third lens L3 is a negative lens composed of a biconcave lens, and the fourth lens L4 is a positive meniscus lens formed convex on the object side, and an aspheric surface is provided on the image side surface (surface number 8) of the fourth lens L4. Forming. The third lens L3 and the fourth lens L4 are closely bonded and joined together to form a cemented lens.

The second group optical system G2 configured by the second lens L2 to the fourth lens L4 has a negative focal length, that is, negative refractive power as a whole. The fifth lens L5 is a positive meniscus lens formed convex on the object side, and an aspherical surface is formed on the object side surface (surface number 10) of the fifth lens L5. The sixth lens L6 is a positive lens composed of a biconvex lens, and the seventh lens L7 is a negative lens composed of a biconcave lens. The eighth lens L8 is a positive lens composed of a biconvex lens having a strong convex surface facing the object side, and an aspherical surface is formed on the object side surface (surface number 16) of the eighth lens L8. The third group optical system G3 configured by the fifth lens L5 to the eighth lens L84 has a positive focal length (positive refractive power) as a whole. The ninth lens L9 is a positive lens composed of a plano-convex lens having a convex surface facing the object side. The fourth group optical system G4 constituted solely by the ninth lens L9 naturally has a positive focal length.
Upon zooming between the short focal wide angle end and the long focal telephoto end, the variable distance between each group and the aperture stop FA, that is, the most image side surface of the first group optical system G1, that is, the first lens L1. The distance d1 between the image side surface (surface number 2) and the most object side surface of the second group optical system G2, that is, the object side surface (surface number 3) of the second lens L2, the second group optical system The distance d2 between the most image side surface of G2, that is, the image side surface (surface number 8) of the fourth lens L4 and the surface of the aperture FA (surface number 9), the surface of the aperture FA (surface number 9), The distance d3 from the most object side surface of the third group optical system G3, that is, the object side surface (surface number 10) of the fifth lens L5, the most image side surface of the third group optical system G3, that is, the eighth lens. L8 image side surface (surface number 17) and the most object side surface of the fourth group optical system G4, that is, the object side surface of the ninth lens L9 (surface number 18) Interval d4 of the changes.

At the time of zooming from the short focus end to the long focus end, the second group optical system G2 holds the position in a fixed manner, and with the zooming from the short focus end to the long focus end, the first group optical system G1 moves monotonously toward the object side, the aperture FA monotonously moves toward the object side, the third group optical system G3 moves monotonously toward the object side, and the fourth group optical system G5 At least the first group optical system G1, the third group optical system G3, the stop FA, and the fourth group optical system G4 move so as to move monotonously toward the image side.
In Example 2, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.14 to 17.13, F = 2.27 to 3.51, and ω = It changes in the range of 43.26-15.38. The characteristics of each optical surface are as shown in the following table.

  In Table 4, each of the first, third, eighth, tenth and sixteenth optical surfaces indicated with “* (asterisk)” in the surface number is an aspheric surface. The parameters in equation (1) are as shown in the following table.

  The variable distance d1 between the first group optical system G1 and the second group optical system G2, the variable distance d2 between the second group optical system G2 and the stop FA, and between the stop FA and the third group optical system G3 The variable interval d3 and the variable interval d4 between the third group optical system G3 and the fourth group optical system G4 are changed as shown in the following table with zooming.

Further, the parameter values according to the conditional expressions described in the second embodiment are as follows.
Conditional parameter value:
tan ⁻¹ (fw / h) = 42.13
| F2 | /f3=0.543
Therefore, the parameter values related to the conditional expression described in the second embodiment are within the range of the conditional expression.

FIG. 3 shows the configuration of the optical system of the zoom lens according to Example 3 of the present invention at the short focal wide angle end and the movement trajectory of each group optical system during zooming.
The zoom lens shown in FIG. 3 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens. A lens L9, an aperture FA, a first filter OF1, a second filter OF2, and a cover glass CG are provided. In this case, the first lens L1 alone constitutes the first group optical system G1, the second lens L2 to the fourth lens L4 constitute the second group optical system G2, and the fifth lens L5 to the eighth lens. L8 constitutes a third group optical system G3, and the ninth lens L9 constitutes a fourth group optical system G4 as a single unit, and is supported by a common support frame or the like appropriate for each group, When zooming or the like, each group operates integrally. FIG. 3 also shows the surface numbers of the optical surfaces. 3 are used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, the same reference numerals as those in FIGS. 1, 2, and 4 are used. Even if the reference numerals are given, they are not necessarily in common with the other embodiments.

In FIG. 3, each optical element constituting the optical system of the zoom lens includes, for example, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture FA, sequentially from the object side such as a subject. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the first filter OF1, the second filter OF2, and the cover glass CG are arranged in this order. It is imaged behind.
The first lens L1 is a positive meniscus lens that is convexly formed on the object side. Of course, the first group optical system G1 constituted solely by the first lens L1 has a positive focal length. The second lens L2 is a negative meniscus lens convexly formed on the object side, and a hybrid aspherical surface (surface number 3) is formed by laying a resin layer on the object-side surface (surface number 4). Yes. The third lens L3 is a negative lens composed of a biconcave lens, and the fourth lens L4 is a positive meniscus lens formed convex on the object side, and an aspheric surface is provided on the image side surface (surface number 8) of the fourth lens L4. Forming.

  The third lens L3 and the fourth lens L4 are closely bonded and joined together to form a cemented lens. The second group optical system G2 configured by the second lens L2 to the fourth lens L4 has a negative focal length, that is, negative refractive power as a whole. The fifth lens L5 is a positive meniscus lens formed convex on the object side, and an aspherical surface is formed on the object side surface (surface number 10) of the fifth lens L5. The sixth lens L6 is a positive lens composed of a biconvex lens, and the seventh lens L7 is a negative lens composed of a biconcave lens. The eighth lens L8 is a positive lens composed of a biconvex lens having a strong convex surface facing the object side, and an aspherical surface is formed on the object side surface (surface number 16) of the eighth lens L8. The third group optical system G3 configured by the fifth lens L5 to the eighth lens L84 has a positive focal length (positive refractive power) as a whole. The ninth lens L9 is a positive lens composed of a plano-convex lens having a convex surface facing the object side. Of course, the fourth group optical system G4 constituted solely by the ninth lens L9 has a positive focal length.

Upon zooming between the short focal wide angle end and the long focal telephoto end, the variable distance between each group and the aperture stop FA, that is, the most image side surface of the first group optical system G1, that is, the first lens L1. The distance d1 between the image side surface (surface number 2) and the most object side surface of the second group optical system G2, that is, the object side surface (surface number 3) of the second lens L2, the second group optical system The distance d2 between the most image side surface of G2, that is, the image side surface (surface number 8) of the fourth lens L4 and the surface of the aperture FA (surface number 9), the surface of the aperture FA (surface number 9), The distance d3 from the most object side surface of the third group optical system G3, that is, the object side surface (surface number 10) of the fifth lens L5, the most image side surface of the third group optical system G3, that is, the eighth lens. L8 image side surface (surface number 17) and the most object side surface of the fourth group optical system G4, that is, the object side surface of the ninth lens L9 (surface number 18) Interval d4 of the changes. At the time of zooming from the short focus end to the long focus end, the second group optical system G2 holds the position in a fixed manner, and with the zooming from the short focus end to the long focus end, the first group optical system G1 monotonously moves toward the object side, the aperture FA monotonously moves toward the object side, the third group optical system G3 monotonously moves toward the object side, and the fourth group optical system G5 At least the first group optical system G1, the third group optical system G3, the stop FA, and the fourth group optical system G4 move so as to move monotonously toward the image side.
In the third embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.13 to 17.12, F = 2.15 to 3.60, and ω = by zooming, respectively. It varies in the range of 43.41 to 14.93. The characteristics of each optical surface are as shown in the following table.

  In Table 7, each optical surface of the third surface, the eighth surface, the tenth surface and the sixteenth surface indicated by adding “* (asterisk)” to the surface number is an aspherical surface. The parameters in the formula are as follows.

  The variable distance d1 between the first group optical system G1 and the second group optical system G2, the variable distance d2 between the second group optical system G2 and the stop FA, and between the stop FA and the third group optical system G3 The variable interval d3 and the variable interval d4 between the third group optical system G3 and the fourth group optical system G4 are changed as shown in the following table with zooming.

In addition, the parameter values according to the conditional expressions described in the third embodiment are as follows.
Conditional parameter value:
tan ⁻¹ (fw / h) = 42.19
| F2 | /f3=0.75
Therefore, the parameter values related to the conditional expressions described in the third embodiment are within the range of the conditional expressions.

FIG. 4 shows the configuration of the optical system of the zoom lens according to Example 4 of the present invention at the short focal wide angle end and the movement trajectory of each group optical system during zooming.
The zoom lens shown in FIG. 4 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens. A lens L9, an aperture FA, a first filter OF1, a second filter OF2, and a cover glass CG are provided. In this case, the first lens L1 alone constitutes the first group optical system G1, the second lens L2 to the fourth lens L4 constitute the second group optical system G2, and the fifth lens L5 to the eighth lens. L8 constitutes a third group optical system G3, and the ninth lens L9 constitutes a fourth group optical system G4 as a single unit, and is supported by a common support frame or the like appropriate for each group, When zooming or the like, each group operates integrally. FIG. 4 also shows the surface numbers of the optical surfaces. In addition, in order to avoid complication of explanation due to an increase in the number of digits of the reference code, each reference code for FIG. 4 is used independently for each embodiment. Therefore, the same reference numerals as those in FIGS. However, they are not necessarily in common with other embodiments.

In FIG. 4, each optical element constituting the optical system of the zoom lens includes, for example, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture FA, sequentially from the object side such as a subject. The fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the first filter OF1, the second filter OF2, and the cover glass CG are arranged in this order. It is imaged behind.
The first lens L1 is a positive meniscus lens that is convexly formed on the object side. Of course, the first group optical system G1 constituted solely by the first lens L1 has a positive focal length. The second lens L2 is a negative meniscus lens convexly formed on the object side, and a hybrid aspherical surface (surface number 3) is formed by laying a resin layer on the object-side surface (surface number 4). Yes. The third lens L3 is a negative lens composed of a biconcave lens, and the fourth lens L4 is a positive meniscus lens formed convex on the object side, and an aspheric surface is provided on the image side surface (surface number 8) of the fourth lens L4. Forming. The third lens L3 and the fourth lens L4 are closely bonded and joined together to form a cemented lens. The second group optical system G2 configured by the second lens L2 to the fourth lens L4 has a negative focal length, that is, negative refractive power as a whole. The fifth lens L5 is a positive meniscus lens formed convex on the object side, and an aspherical surface is formed on the object side surface (surface number 10) of the fifth lens L5.

The sixth lens L6 is a positive lens composed of a biconvex lens, and the seventh lens L7 is a negative lens composed of a biconcave lens. The eighth lens L8 is a positive lens composed of a biconvex lens having a strong convex surface facing the object side, and an aspherical surface is formed on the object side surface (surface number 16) of the eighth lens L8. The third group optical system G3 configured by the fifth lens L5 to the eighth lens L84 has a positive focal length (positive refractive power) as a whole. The ninth lens L9 is a positive lens composed of a plano-convex lens having a convex surface facing the object side. The fourth group optical system G4 constituted solely by the ninth lens L9 naturally has a positive focal length.
Upon zooming between the short focal wide angle end and the long focal telephoto end, the variable distance between each group and the aperture stop FA, that is, the most image side surface of the first group optical system G1, that is, the first lens L1. The distance d1 between the image side surface (surface number 2) and the most object side surface of the second group optical system G2, that is, the object side surface (surface number 3) of the second lens L2, the second group optical system The distance d2 between the most image side surface of G2, that is, the image side surface (surface number 8) of the fourth lens L4 and the surface of the aperture FA (surface number 9), the surface of the aperture FA (surface number 9), The distance d3 from the most object side surface of the third group optical system G3, that is, the object side surface (surface number 10) of the fifth lens L5, the most image side surface of the third group optical system G3, that is, the eighth lens. L8 image side surface (surface number 17) and the most object side surface of the fourth group optical system G4, that is, the object side surface of the ninth lens L9 (surface number 18) Interval d4 of the changes.

At the time of zooming from the short focus end to the long focus end, the second group optical system G2 holds the position in a fixed manner, and with the zooming from the short focus end to the long focus end, the first group optical system G1 monotonously moves toward the object side, the aperture FA monotonously moves toward the object side, the third group optical system G3 monotonously moves toward the object side, and the fourth group optical system G5 At least the first group optical system G1, the third group optical system G3, the stop FA, and the fourth group optical system G4 move so as to move monotonously toward the image side.
In the fourth embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.14 to 17.14, F = 2.13 to 3.58, and ω = It varies in the range of 43.44 to 14.92. The characteristics of each optical surface are as shown in the following table.

  In Table 10, the optical surfaces of the third surface, the eighth surface, the tenth surface, and the seventeenth surface indicated by adding “* (asterisk)” to the surface number are aspherical surfaces. The parameters in the formula are as follows.

  The variable distance d1 between the first group optical system G1 and the second group optical system G2, the variable distance d2 between the second group optical system G2 and the stop FA, and between the stop FA and the third group optical system G3 The variable interval d3 and the variable interval d4 between the third group optical system G3 and the fourth group optical system G4 are changed as shown in the following table with zooming.

Further, the parameter values related to the conditional expressions described in the fourth embodiment are as follows.
Conditional parameter value:
tan ⁻¹ (fw / h) = 42.19
| F2 | /f3=0.552
Therefore, the parameter values related to the conditional expressions described in the fourth embodiment are within the range of the conditional expressions.
5 to 7 show aberration curves of spherical aberration, astigmatism, distortion and coma aberration in the zoom lens shown in FIG. 1 according to Example 1 described above, and among these, FIG. FIG. 6 is an aberration curve diagram at the intermediate focal length, and FIG. 7 is an aberration curve diagram at the long focus telephoto end. In each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, the broken line represents meridional, the thick line represents the d line, and the thin line represents the g line.

8 to 10 show aberration curves of spherical aberration, astigmatism, distortion and coma aberration in the zoom lens shown in FIG. 2 according to Example 2 described above, and FIG. FIG. 9 is an aberration curve diagram at the intermediate focal length, and FIG. 10 is an aberration curve diagram at the long focal telephoto end. Also in this case, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, the broken line represents meridional, the thick line represents the d line, and the thin line represents the g line. .
11 to 13 show aberration curves of spherical aberration, astigmatism, distortion and coma aberration in the zoom lens shown in FIG. 3 according to Example 3 described above, and FIG. FIG. 12 is an aberration curve diagram at the intermediate focal length, and FIG. 13 is an aberration curve diagram at the long focal telephoto end. Also in this case, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, the broken line represents meridional, the thick line represents the d line, and the thin line represents the g line. .

14 to 16 show aberration curve diagrams of spherical aberration, astigmatism, distortion aberration, and coma aberration in the zoom lens shown in FIG. 4 according to Example 4 described above, and FIG. FIG. 15 is an aberration curve diagram at the intermediate focal length, and FIG. 16 is an aberration curve diagram at the long focal telephoto end. Also in this case, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, the broken line represents meridional, the thick line represents the d line, and the thin line represents the g line. .
According to the aberration curve diagrams of FIGS. 5 to 16, all the zoom lenses having the configurations shown in FIGS. 1 to 4 according to the first to fourth embodiments of the present invention described above are corrected favorably. It can be seen that it is suppressed or suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention in which the zoom lens according to the present invention as shown in the first to fourth embodiments described above is employed as a photographing optical system to constitute a camera will be described with reference to FIGS. This will be described with reference to FIG. FIG. 17 is a perspective view of the object, that is, a photographic lens barrel showing the appearance of the camera viewed from the front side that is the subject side, in a retracted state and FIG. FIG. 19 is a perspective view showing the external appearance of the camera as seen from the back side that is the photographer side, and FIG. 20 is a block diagram showing the functional configuration of the camera. . Although a camera is described here, a camera in which a camera function is incorporated in a personal digital assistant such as a so-called PDA (personal data assistant) or a mobile phone has recently appeared. Such a portable information terminal device also includes substantially the same function and configuration as a camera although the appearance is slightly different. Even if the zoom lens according to the present invention is adopted in such a portable information terminal device, Good.
As shown in FIGS. 17, 18 and 19, the camera includes a photographing lens 101, a shutter button 102, a zoom lever 103, a viewfinder 104, a strobe 105, a liquid crystal monitor 106, an operation button 107, a power switch 108, a memory and a communication card. A slot 109 and the like are provided. Furthermore, as shown in FIG. 20, the camera also includes a light receiving element 201, a signal processing device 202, an image processing device 203, a central processing unit (CPU) 204, a semiconductor memory 205, a communication card 206, and the like.

The camera includes a photographic lens 101 and a light receiving element 201 as an area sensor such as a CCD (charge coupled device) imaging device, and is an object to be photographed, that is, a subject formed by the photographic lens 101 that is a photographing optical system. The image is read by the light receiving element 201. As the photographing lens 101, the zoom lens according to the present invention as described in the first to fourth embodiments is used. Specifically, the lens unit is configured using a lens or the like that is an optical element configuring the zoom lens. This lens unit has a mechanism for holding each lens or the like so that it can be moved and operated at least for each lens group. The photographing lens 101 incorporated in the camera is usually incorporated in the form of this lens unit.
The output of the light receiving element 201 is processed by the signal processing device 202 controlled by the central processing unit 204 and converted into digital image information. The image information digitized by the signal processing device 202 is subjected to predetermined image processing in the image processing device 203 which is also controlled by the central processing unit 204 and then recorded in the semiconductor memory 205 such as a nonvolatile memory. In this case, the semiconductor memory 205 may be a memory card loaded in the memory and communication card slot 109 or a semiconductor memory built in the camera body. The liquid crystal monitor 106 can display an image being photographed, or can display an image recorded in the semiconductor memory 205.

The image recorded in the semiconductor memory 205 can also be transmitted to the outside via the memory and the communication card 206 loaded in the communication card slot 109.
When the camera is carried, the taking lens 101 is in a retracted state as shown in FIG. 17 and is buried in the camera body. When the user operates the power switch 108 to turn on the power, as shown in FIG. The lens barrel is extended and protrudes from the camera body. At this time, in the lens barrel of the photographing lens 101, the optical systems of the respective groups constituting the zoom lens are, for example, arranged at the short focal end, and by operating the zoom lever 103, the optical systems of the respective groups of optical systems are arranged. The arrangement can be changed, and the zooming operation to the long focal end can be performed. Note that it is desirable that the optical system of the finder 104 is also scaled in conjunction with the change in the angle of view of the photographing lens 101.
In many cases, focusing is performed by half-pressing the shutter button 102. Focusing in the zoom lens (the zoom lens defined in claims 1 to 9 or shown in the first to fourth embodiments) constituted by four groups of positive-negative-positive-positive according to the present invention is as follows. The fourth group optical system G4 can be moved, or the light receiving element can be moved. When the shutter button 102 is further pushed down to the fully depressed state, photographing is performed, and then the processing as described above is performed.

When the image recorded in the semiconductor memory 205 is displayed on the liquid crystal monitor 106 or transmitted to the outside via the communication card 206 or the like, the operation button 107 is operated in a predetermined manner. The semiconductor memory 205 and the communication card 206 are used by being loaded into dedicated or general-purpose slots such as the memory and communication card slot 109, respectively.
When the photographic lens 101 is in the retracted state, the zoom lens groups do not necessarily have to be aligned on the optical axis, and a mechanism that accommodates a plurality of optical systems in parallel can be used. Further thinning of the camera can be realized.
As described above, the photographing lens 101 using the zoom lens as described in the first to fourth embodiments can be used as the photographing optical system in the camera or the portable information terminal device as described above. Accordingly, it is possible to realize a small camera or a portable information terminal device with high image quality using a light receiving element of 3 to 5 million pixel class.

1 is a cross-sectional view along an optical axis schematically showing the configuration of an optical system of a zoom lens according to Example 1 of the present invention. It is sectional drawing along the optical axis which shows typically the structure of the optical system of the zoom lens which concerns on Example 2 of this invention. It is sectional drawing along the optical axis which shows typically the structure of the optical system of the zoom lens which concerns on Example 3 of this invention. It is sectional drawing along the optical axis which shows typically the structure of the optical system of the zoom lens which concerns on Example 4 of this invention. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal point of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 2 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end of the zoom lens according to Embodiment 1 of the present invention shown in FIG. 1. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal point of the zoom lens according to Example 2 of the present invention shown in FIG. 2. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Example 2 of the present invention shown in FIG. 2. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end of the zoom lens according to Example 2 of the present invention shown in FIG. 2. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal end of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal end of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. It is the perspective view seen from the object side which shows typically the appearance composition of the embodiment of the camera concerning the present invention, and shows the state where the photographing lens was buried in the body of the camera. It is the perspective view seen from the object side which shows typically the external appearance structure which shows the state which the imaging lens of the camera in FIG. 17 protrudes from the body. It is the perspective view seen from the photographer side which shows typically the external appearance structure of the camera of FIG. It is a block diagram which shows typically the function structure of the camera of FIG.

Explanation of symbols

G1 First group optical system G2 Second group optical system G3 Third group optical system G4 Fourth group optical system L1 to L9 First lens to ninth lens FA Aperture OF1, OF2 Filter CG Cover glass 101 Shooting lens 102 Shutter button 103 Zoom lever 104 Viewfinder 105 Strobe 106 LCD monitor 107 Operation button 108 Power switch 109 Memory and communication card slot 201 Light receiving element (area sensor)
202 Signal Processing Unit 203 Image Processing Unit 204 Central Processing Unit (CPU)
205 Semiconductor memory 206 Communication card, etc. d1, d2, d3, d4 interval

Claims (11)

The first group optical system having a positive focal length, the second group optical system having a negative focal length, the third group optical system having a positive focal length, and the positive focal length in order from the object side In a zoom lens comprising a fourth group optical system having
The first group optical system is composed of a single positive lens, and the first group optical system, the third group optical system, and the fourth group accompanying zooming from the short focus wide angle end to the long focus telephoto end. A zoom lens, wherein an optical system moves on an optical axis, and the second group optical system is fixedly arranged with respect to an image plane. The focal length of the short focal wide angle end is fw, the maximum image height of the image to be formed is h,
Conditional expression:
35 <tan ⁻¹ (fw / h)
The zoom lens according to claim 1, wherein: If the focal length of the i-th group optical system (i = 1 to 3) is fi,
Conditional expression:
0.6 <| f2 | / f3 <0.8
The zoom lens according to claim 1, wherein the zoom lens satisfies the following. The positive lens constituting the first group optical system has a refractive index Nd and an Abbe number νd.
Conditional expression:
Nd> 1.55
νd> 55
4. The zoom lens according to claim 1, wherein the zoom lens is formed of a glass material that satisfies the above.   5. The zoom lens according to claim 1, wherein an optical surface closest to the object side of the second group optical system is configured as an aspherical surface.   6. The zoom lens according to claim 5, wherein an optical surface closest to the object side of the first group optical system is an aspherical surface.   The zoom lens according to claim 1, wherein the third group optical system includes a cemented lens.   The zoom lens according to claim 1, wherein an optical surface closest to the image side of the third group optical system is an aspherical surface.   9. The zoom lens according to claim 1, wherein focusing is performed by moving the fourth group optical system in an optical axis direction. 10.   A camera comprising the zoom lens according to any one of claims 1 to 9 as a photographing optical system.   A portable information terminal device having a camera function unit and including the zoom lens according to claim 1 as a photographing optical system of the camera function unit.

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