JP3473351B2 - Zoom lens device - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a zoom lens system equipped with a zoom lens system used in a compact photographing optical system, and more specifically, it is suitable for a photographing optical system of a digital input / output device such as a digital still camera or a digital video camera. The present invention relates to a zoom lens device including a compact and zoom lens system having a high zoom ratio.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and the like, digital still cameras and digital video cameras (hereinafter simply referred to as digital cameras), which can easily capture image information into digital devices, have become widespread at the individual user level. It's starting. It is expected that such digital cameras will continue to become more popular as image information input devices.

Generally, the image quality of a digital camera is determined by the number of pixels of a solid-state image pickup device such as CCD (charge coupled device). At present, the mainstream of general-purpose digital cameras is a so-called VGA class solid-state image sensor having a pixel number of about 330,000 pixels. However, it cannot be denied that the image quality of this VGA class camera is significantly inferior to that of a camera using a conventional silver salt film. For this reason,
Recently, even general-purpose digital cameras have been desired to have high image quality exceeding 1 million pixels, and it is required that the photographing optical systems of these digital cameras also have high image quality.

Further, even in these general-purpose digital cameras, it is desired to perform image scaling, especially optical scaling with little image deterioration, and therefore, in recent years, for digital cameras satisfying high image quality with high magnification. A zoom lens system is required.

[0005]

However, in the conventionally proposed zoom lens system for a digital camera,
Most of those that satisfied the high image quality of more than 0,000 pixels were those that used interchangeable lenses for single-lens reflex cameras, or very large digital cameras for business use. Therefore, such a zoom lens system is very large and expensive, and it cannot be said that it is suitable for a general-purpose digital camera.

On the other hand, for the photographing optical system of such a digital camera, the photographing optical system of a lens shutter camera for a silver salt film, which has been remarkably compacted and has a high zoom ratio in recent years, may be used. Conceivable.

However, when the photographing optical system of the lens shutter camera is used as it is for the digital camera,
The light condensing performance of the microlens provided on the front surface of the solid-state image sensor included in the digital camera cannot be sufficiently satisfied, and the brightness of the image in the central part of the image and the peripheral part of the image is extremely changed. There is a problem that it will end up. This is a problem that occurs because the exit pupil of the photographing optical system of the lens shutter camera is located near the image plane, and the off-axis light flux emitted from the photographing optical system is obliquely incident on the image plane. . In order to solve this problem, if the exit pupil position of the photographing optical system of the conventional lens shutter camera is tried to be separated from the image plane, it is inevitable that the entire photographing optical system becomes large.

In view of the above problems, it is an object of the present invention to provide a zoom lens device equipped with a completely new and compact zoom lens system which satisfies high image quality with a high zoom ratio.

To achieve the above object, the zoom lens device of the present invention comprises, in order from the object side, a zoom lens system and a solid-state image pickup device for receiving an optical image formed by the zoom lens system. This zoom lens system has the following features. A zoom lens system according to claim 1 has, in order from the object side, a first lens group having a positive power, a second lens group having a negative power, and a third lens group having a positive power. A zoom lens system that performs zooming by moving at least the first lens group,
The lens group includes, in order from the object side, a negative lens, a positive lens, and a positive lens, and the condition of an aspherical surface or less in the third lens group.
Has at least one aspherical surface satisfying (17), and
The condition (9) is satisfied. 0.7 <m1 / Z <3.0 (9) -0.1 <φ × (N '-N) × d / dH {X (H)-X0 (H)} <0
(17) However, m1: movement amount (mm) when zooming from the shortest focal length state of the first lens group to the longest focal length state, Z: zoom ratio (Z = ft / fw: shortest focal length state and longest focal length state) (Focal length ratio in focal length state), φ: power of aspherical surface, N: refractive index of d-line of medium on the object side of the aspherical surface, N ′: refractive index of d-line of medium of aspherical surface on the image side, H : Height in the direction perpendicular to the optical axis, X (H): Displacement in the optical axis direction at the height H of the aspherical surface , X0 (H): Displacement in the optical axis direction at the height H of the reference spherical surface , .

0.8 <m1 / Z <3.0 where m1: the amount of movement (mm) of the first lens group during zooming from the shortest focal length state to the longest focal length state, Z: zoom ratio (Z = ft / fw : Focal length ratio between the shortest focal length state and the longest focal length state).

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. It should be noted that in the present specification, “power” represents an amount defined by the reciprocal of the focal length, and its deflection action is not limited to the deflection by the surfaces of media having different refractive indices, but also the deflection by diffraction or Deflection due to the refractive index distribution in the medium is also included.

1 to 4 are sectional views showing the lens arrangement of the zoom lens systems according to the first to fourth embodiments of the present invention in the shortest focal length state. The zoom lens system of each embodiment has, in order from the object side, a first lens group Gr1 having a positive refractive power, a second lens group Gr2 having a negative refractive power, a diaphragm S, and a positive refractive power. The zoom lens includes a third lens group Gr3 and a low-pass filter LF, and the distance between the first lens group and the second lens group increases during zooming from the shortest focal length end to the longest focal length end. The first lens group and the third lens group are arranged so that the distance between the lens group and the third lens group decreases.
This is a zoom lens system in which the lens group moves. In addition, the arrow attached in the drawing schematically represents the movement loci of the respective lens groups Gr1 to Gr3, the diaphragm S, and the low-pass filter LF at the time of zooming from the shortest focal length state to the longest focal length state.

The zoom lens system of the first embodiment comprises, in order from the object side, a negative meniscus lens L1 convex toward the object side,
A first lens group Gr1 including a biconvex positive lens L2 and a positive meniscus lens L3 convex on the object side, a negative meniscus lens L4 convex on the object side, a biconvex positive lens L5, and a positive lens convex on the image side. Meniscus lens (front surface is aspherical surface) L6 and biconcave negative lens (back surface is aspherical surface) L7 cemented lens DL1
A second lens group Gr2 including an aperture stop S, a positive meniscus lens L8 convex on the object side, a biconvex positive lens L9, a biconcave negative lens L10, and a positive meniscus lens convex on the object side (rear surface Is an aspherical surface) L11 and the third lens group G
r3 and a low-pass filter F. Upon zooming from the shortest focal length state to the longest focal length state, the first lens group Gr1, the third lens group Gr3, and the diaphragm S move to the object side, and the second lens group Gr2 temporarily moves to the object side and then the image. It makes a U-turn to move to the side, and the low-pass filter F is fixed.

In the zoom lens system of the second embodiment, in order from the object side, a cemented lens DL1 of a negative meniscus lens L1 convex to the object side and a biconvex positive lens L2, and a positive meniscus lens L3 convex to the object side are provided. First lens group Gr consisting of
1. Negative meniscus lens convex on the object side (front surface is aspheric)
L4, a biconcave negative lens L5, and a biconvex positive lens L6
And a negative meniscus lens convex on the image side (the rear surface is an aspherical surface) L
7, a second lens group Gr2, a diaphragm S, a biconvex positive lens (aspherical front surface) L8, a negative meniscus lens L9 convex to the object side, and a positive meniscus lens convex to the object side (rear surface). Is an aspherical surface) L10 and the third lens group Gr
3 and a low pass filter F. Upon zooming from the shortest focal length state to the longest focal length state, the first lens group Gr1, the third lens group Gr3, and the diaphragm S
Move to the object side, the second lens group Gr2 makes a U-turn to move to the object side and then to the image side, and the low-pass filter F is fixed.

In the zoom lens system of the third embodiment, in order from the object side, a negative meniscus lens L1 having a convex surface on the object side,
A first lens group Gr including a positive meniscus lens L2 having a convex surface on the object side and a positive meniscus lens L3 having a convex surface on the object side.
1. A negative meniscus lens L4 having a convex surface on the object side, a biconvex positive lens L5, and a positive meniscus lens L6 having a convex surface on the image side.
The second lens group Gr including the cemented lens DL1 with the aspherical front surface and the negative biconcave lens L7 (aspherical rear surface).
2, an aperture stop S, a biconvex positive lens L8 (the front surface is an aspherical surface),
Biconvex positive lens L9, negative meniscus lens L10 convex to the object side, and negative meniscus lens L11 convex to the image side
And a third lens group Gr3 including a biconcave negative lens L12 (both aspherical surfaces) and a low-pass filter F. During zooming from the shortest focal length state to the longest focal length state, the first lens group Gr1 and the third lens group Gr3 move to the object side, the second lens group Gr2 moves to the image side, and the diaphragm S and the low-pass filter are moved. F is fixed.

In the zoom lens system of the fourth embodiment, in order from the object side, a cemented lens DL1 of a negative meniscus lens L1 convex to the object side and a biconvex positive lens L2, and a positive meniscus lens L3 convex to the object side are provided. First lens group Gr consisting of
1. Negative meniscus lens convex on the object side (front surface is aspheric)
A second lens group Gr2 including L4, a biconcave negative lens L5 and a cemented lens DL2 of a biconvex positive lens L6, a diaphragm S, a biconvex positive lens (aspherical front surface) L7, and a convex surface on the object side. Negative meniscus lens L8, a cemented lens DL3 of a negative meniscus lens L9 convex to the object side and a positive meniscus lens L10 convex to the object side, and a positive meniscus lens convex to the object side (the front side is an aspherical surface) Third consisting of L11
It is composed of a lens group Gr3 and a low-pass filter F. When zooming from the shortest focal length state to the longest focal length state, the first lens group Gr1 and the third lens group G
The r3 and the stop S integrated with the third lens group move to the object side, the second lens group Gr2 moves to the image side, and the low-pass filter F is fixed.

The conditions to be satisfied by the zoom lens system of each embodiment will be described below. Note that it is not necessary to satisfy all the conditions described below at the same time. It is desirable that the zoom lens system of each embodiment satisfy the condition defined by the following conditional expression range (1). 3.0 <f1 / fw <9.0 (1) where f1 is the focal length of the first lens group, and fw is the focal length of the entire system in the shortest focal length state.

The above conditions are conditions for controlling the focal length of the first lens group. When the upper limit of conditional expression range (1) is exceeded, the focal length of the first lens group becomes too large, and the movement amount of the first lens group during zooming from the shortest focal length state to the longest focal length state becomes large. Therefore, the total length of the zoom lens system in the longest focal length state becomes large, and a compact zoom lens system cannot be obtained. On the other hand, when the value goes below the lower limit of the above condition range (1), the power of the first lens group becomes large, and the aberration generated in the first lens group, especially the spherical aberration at the long focal length side becomes large, and as a whole. It is not preferable because good optical performance cannot be obtained.

Regarding the above conditions, in the conditional expression range (1), the following conditional expression ranges (2a) to (1c) are given.
It is more desirable to be satisfied in the order of. 3.5 <f1 / fw <9.0 (1a) 4.5 <f1 / fw <9.0 (1b) 5.0 <f1 / fw <9.0 (1c) The zoom lens system of each embodiment is defined by the following conditional expression range (2). It is desirable to satisfy the following conditions. -1.3 <f2 / fw <-0.7 (2) where f2 is the focal length of the second lens group.

The above conditions are conditions that regulate the focal length of the second lens group. When the lower limit value of the conditional expression range (2) is exceeded, the focal length of the second lens group becomes small, and the axial distance between the second lens group and the third lens group in the shortest focal length state becomes large, resulting in the shortest focus. The total length of the distance state becomes too large. As a result, the lens diameters of the lenses included in the first lens group and the second lens group become large, which is not preferable. vice versa,
If the upper limit of conditional expression range (2) is exceeded, the power of the second lens group will become large, and the aberrations occurring in the second lens group, especially the Petzval sum, will become negatively large, and the overall Petzval sum will become negatively excessive. Since it becomes large, it is not preferable because good optical performance cannot be obtained as a whole.

Regarding the above conditions, in the conditional expression range (2), the following conditional expression ranges (2a) to (2b) are given.
It is more desirable to be satisfied in the order of. -1.3 <f2 / fw <-0.8 (2a) -1.4 <f2 / fw <-0.8 (2b) The zoom lens system of each embodiment must satisfy the condition defined by the following conditional expression range (3). Is desirable. 1.1 <f3 / fw <1.8 (3) where f3 is the focal length of the third lens group.

The above conditions are conditions that regulate the focal length of the third lens group. If the upper limit of conditional expression range (3) is exceeded, the focal length of the third lens group becomes too large.
The total length in the longest focal length state becomes too large, and a compact zoom lens system cannot be obtained. On the contrary, when the value goes below the lower limit of the conditional expression range (3), the power of the third lens group becomes large, and the aberration generated in the third lens group, especially the coma aberration becomes large. Even if an aspherical surface is provided in any of the above positions, the correction cannot be made, and eventually, good optical performance cannot be obtained as a whole, which is not desirable.

Regarding the above conditions, it is more preferable to satisfy the following conditional expression range (3a) in the conditional expression range (3). 1.8 <f3 / fw <1.9 (3a) It is desirable that the zoom lens system of each embodiment satisfies the condition defined by the following conditional expression range (4). 1.0 <img × R <15.0 (4) However, img: maximum image height (unit: mm), R: lens surface that is closest to the image side, excluding filters, etc., of the lens surfaces that make up the zoom lens system The diameter (unit is mm) is.

The above conditions are conditions for balancing the conditions for correction of the size as the zoom lens diameter and various aberrations and the conditions peculiar to the photographing optical system for digital cameras. Generally, in a photographing optical system used in a digital camera using a solid-state image sensor, in order to sufficiently satisfy the condensing performance of a microlens provided on the front surface of the solid-state image sensor, the incident light beam is converted into the light flux of the microlens. It is necessary to make the light incident substantially perpendicular to. Therefore, the photographing optical system for a digital camera is required to be substantially telecentric on the image side in addition to correcting various aberrations as in the photographing optical system of a normal camera for silver salt film. When the value exceeds the upper limit of the conditional expression range (4), it becomes unnecessary for the zoom lens system to be substantially telecentric on the image side, and various aberrations, particularly negative distortion aberrations on the short focal length side, become too large. As the correction becomes difficult,
Undesirably, the image plane falls down to the under side remarkably.
On the other hand, if the lower limit value of the conditional expression range (4) is exceeded, it is difficult to satisfy that it is substantially telecentric, which is not desirable. In particular, if it is attempted to improve the telecentricity in a state where the lower limit value is exceeded, the back focus of the zoom lens system becomes unnecessarily large and the size of the optical system becomes large, which is not desirable.

Regarding the above conditions, it is more preferable to satisfy the following conditional expression range (4a) in the conditional expression range (4). 6.5 <img × R <9.5 (4a) Like the zoom lens system of each embodiment, in order from the object side, the first lens group having positive power, the second lens group having negative power, and the positive lens group In the zoom lens system including the third lens group having power,
It is desirable that the lens group includes a positive lens element including a positive lens having a strong curvature surface provided closest to the object side and a negative lens element including at least one negative lens. With this configuration, it becomes possible to satisfactorily correct various aberrations.

Regarding the positive lens provided closest to the object in the third lens group, the following conditional expression (5) is satisfied.
It is desirable to satisfy the conditions specified in. 0.1 <Ra / f3 <3.0 (5) where Ra is the radius of curvature of the image side surface of the positive lens closest to the object side in the third lens group, and f3 is the focal length of the third lens group.

The above condition defines the ratio of the radius of curvature of the image side surface of the positive lens arranged closest to the object side of the third lens group and the focal length of the third lens group. This is a condition relating to aberration correction capability. Conditional expression range (5)
When the value exceeds the upper limit of, the curvature of the image side surface of the positive lens becomes too weak, and the tendency for spherical aberration to flow to the over side becomes strong, which is not desirable. On the other hand, when the value goes below the lower limit of the conditional expression range (5), the curvature of the image side surface of the positive lens becomes too strong, and the spherical aberration tends to fall toward the under side, which is not desirable.
If the lower limit of conditional expression (5) is exceeded, the radius of curvature of the image side surface of the positive lens becomes too small, which is difficult to manufacture and is not desirable.

As in the zoom lens system of each embodiment, in order from the object side, the first lens group having positive power, the second lens group having negative power, and the third lens group having positive power. In the zoom lens system configured by, the second lens group includes, in order from the object side, a second lens group first sub group including a lens having a concave surface having a strong curvature facing the image side, and at least an object side. It is desirable that the second lens group and the second sub-group be composed of one positive lens and one negative lens. By configuring the second lens group in this way, when the light ray is emitted from the concave surface of the second lens group first sub-group having a strong curvature, the exit angle of the off-axis ray is increased, particularly on the short focal length side. Since the exit angle of the axial ray becomes small, it becomes possible to easily correct the aberrations of the second lens group and the second sub group and thereafter.

Further, it is desirable that the concave surface of the first sub-group of the second lens group satisfies the condition defined by the following conditional expression range (6). -1.6 <R2n / f2 <-0.6 (6) where R2n is the radius of curvature of the concave surface of the first sub group of the second lens group, and f2 is the focal length of the second lens group.

The above condition defines the ratio of the radius of curvature of the concave surface of the first sub-group of the second lens group, which has a strong curvature, to the focal length of the second lens group, and is a condition concerning the aberration correction capability of the concave surface. Is. If the lower limit of the conditional expression range (6) is exceeded, the curvature of the concave surface becomes too weak, and the above-mentioned action is taken, that is, the exit angle and the axis of the off-axis light ray when the light ray incident on the concave surface is emitted from the concave surface. It becomes impossible to sufficiently achieve the effect of reducing the emission angle of the upper ray. As a result, when the lower limit value of the conditional expression range (6) is exceeded, the light ray emitted from the first sub-group of the second lens group is emitted to the succeeding group while the angle between the off-axis ray and the on-axis ray is large. , Aberration on the image plane,
In particular, field curvature and coma cannot be corrected by the subsequent group, which is not desirable. On the other hand, when the value exceeds the upper limit of the conditional expression range (6), the curvature of the concave surface becomes too strong, and a very large aberration occurs independently on the concave surface. Therefore, it is possible to correct this aberration on another surface. It is impossible and undesirable. On the other hand, when the value exceeds the upper limit of the conditional expression range (6), the radius of curvature of the concave surface becomes too small, which is difficult to manufacture, which is not desirable.

Furthermore, the second sub-group of the second lens group comprises, in order from the object side, a biconvex positive single lens, a positive lens having a convex surface on the image side, and a biconcave negative lens. It is desirable that it is composed of a cemented lens. The second lens group has a negative power as a whole, but when correcting chromatic aberration in the second lens group, at least one positive lens and at least one negative lens are included in the second lens group. Must include lens. On the other hand, in the first sub group of the second lens group, there is a concave surface having a strong curvature on the image side as described above. Therefore, in order to achieve the function of this concave surface, the first sub group of the second lens group is Cannot use a positive lens having a strong power for correcting the chromatic aberration generated on the concave surface. Therefore, in order to correct the chromatic aberration of the entire second lens group, the second sub-group of the second lens group includes a biconvex positive single lens, a positive lens having a convex surface on the image side, and a biconcave negative lens. And a cemented lens formed by cementing and.

Further, it is desirable that the positive lens of the second sub-group of the second lens group satisfies the condition defined by the following conditional expression range (6) '. -2.5 <f2p / f2 <-1.0 (6) 'where f2p is the focal length of the positive lens of the second sub-group of the second lens group, and f2 is the focal length of the second lens group.

The above condition defines the ratio between the focal length of the positive lens of the second sub-group of the second lens group and the focal length of the second lens group, and is a condition relating to the chromatic aberration correction of the second lens group. is there. When the value goes below the lower limit of the conditional expression range (6) ′, the power of the positive lens becomes too weak and chromatic aberration generated in the second lens group becomes large, which is not desirable. On the contrary, if the upper limit of conditional expression (6) 'is exceeded, the power of the positive lens becomes too strong, and the power of the negative lens included in the second lens group must be made strong in order to correct the chromatic aberration of the second lens group. I will have to do it. As a result, although chromatic aberration can be corrected, it becomes difficult to correct normal monochromatic aberration, which is not desirable.

In the zoom lens system of each embodiment, the first lens group includes, in order from the object side, a negative lens having a convex surface on the negative object side, a biconvex positive lens, and a positive lens having a convex surface on the object side. Have In order to correct chromatic aberration with the first lens group, it is necessary to provide at least one positive lens and at least one negative lens in the first lens group.
However, if the first lens group having positive power as a whole is configured by using only one positive lens and one negative lens, it is difficult to correct aberrations on the long focal length side, particularly spherical aberration. become. Further, in order to correct high-order spherical aberration on the long focal length side, the first lens group through which axial rays pass at a high ray height has a degree of freedom in design (number of lenses) for further aberration correction. It is preferable to give. Further, if the first lens group is configured by using only one positive lens and one negative lens, it becomes difficult to correct chromatic aberration within the range of optical constants of existing glass and plastic.

As described above, the first lens group comprises, in order from the object side, a negative lens having a convex surface on the negative object side, a biconvex positive lens, and a positive lens having a convex surface on the object side. In this case, it is desirable to satisfy each condition defined by the following conditional expression ranges (7) and (8). νn <35 (7) νp> 50 (8) where νn is the Abbe number of the negative lens of the first lens group, and νp is the Abbe number of the positive lens of the first lens group.

The above conditional expression is a condition for correcting chromatic aberration in the first lens group. 1 of the first lens group
By appropriately defining the Abbe numbers of the negative lenses and the two positive lenses, it is possible to excellently correct chromatic aberration in the first lens group.

With regard to the conditional expression range (7), more satisfactory chromatic aberration can be corrected by further satisfying the following conditional expression range.

Νn <32 (7a) νn <30 (7b) In the zoom lens system of each embodiment, the first lens unit moves toward the object side during zooming from the shortest focal length state to the longest focal length state. It is composed. This configuration
It is preferable that the total length of the zoom lens system in the state of the shortest focal length can be made compact and the lens diameter of the lenses constituting the first lens group can be made small. As described above, when the first lens group moves toward the object side during zooming from the shortest focal length state to the longest focal length state, the condition defined by the following conditional expression range (9) may be satisfied. desirable. 0.7 <m1 / Z <3.0 (9) However, m1: The amount of movement (mm) when zooming from the shortest focal length state of the first lens group to the longest focal length state, Z: Zoom ratio (Z = ft / fw : Focal length ratio between the shortest focal length state and the longest focal length state) The above condition represents the relationship between the zoom amount and the movement amount of the first lens group during zooming from the shortest focal length state to the longest focal length state. There is. In general, the larger the zoom ratio, the larger the movement amount. The condition defined by the conditional expression range (9) is a condition for providing a zoom lens which is compact and has good optical performance by appropriately defining the movement amount of the first lens group. Conditional expression range (9)
When the value exceeds the upper limit of, the amount of movement of the first lens unit is too large as compared with the zoom ratio, and the total length in the longest focal length state increases too much, so that a compact zoom lens cannot be obtained. On the contrary, if the lower limit value of the conditional expression range (9) is exceeded,
The amount of movement of the first lens group becomes too small. When the amount of movement of the first lens group becomes small, the zoom ratio cannot be achieved unless the power of the first lens group is increased. As a result, the power of the first lens group becomes too large, the amount of aberration generated in the first lens group becomes large, and it becomes impossible to obtain good optical performance as a whole.

Regarding the above condition, it is more preferable to satisfy the following conditional expression range (9a) in the conditional expression range (9). 0.8 <m1 / Z <3.0 (9a) Thus, when the first lens group moves toward the object side during zooming from the shortest focal length state to the longest focal length state, the following conditional expression range (10) It is desirable to satisfy the conditions specified in. 0.8 <M1WM / M1MT <2.5 (10) However, M1WM: the amount of movement of the first lens group from the shortest focal length state to the intermediate focal length state, M1MT: the first lens group from the intermediate focal length state to the longest focal length state The intermediate focal length is (fw × ft) ^1/2 , where fw is the focal length in the shortest focal length state and ft is the focal length in the longest focal length state.

The above condition is a condition that defines the ratio of the amount of movement of the first lens unit from the shortest focal length state to the intermediate focal length state and the amount of movement from the intermediate focal length state to the longest focal length state. It means that the amount of movement of the first lens group is changed from the shortest focal length state to the intermediate focal length state from the focal length state to the longest focal length state. In particular, by making the amount of movement of the first lens group from the shortest focal length state to the intermediate focal length state relatively large, it becomes possible to make the entrance pupil position in the intermediate focal length range far from the image plane, The flare component of off-axis rays can be cut.

Regarding the above conditions, in the conditional expression range (10), the following conditional expression ranges (10a) to (1)
It is more desirable to satisfy 0b). 0.9 <M1WM / M1MT <2.5 (10a) 1.2 <M1WM / M1MT <2.2 (10b) The zoom lens system of each embodiment has the following conditional expression range (1
It is desirable to satisfy the conditions specified in 1). 1 <max (T1, T2, T3) / fw <4 (11) However, Ti: thickness on the optical axis of the i-th group, and max (T1, T2, T3) is its maximum value.

The above conditions are conditions for achieving a compact and high-magnification zoom lens system. If the lower limit of conditional expression range (11) is exceeded, the thickness on the optical axis of each lens group becomes too small, and the processing requirements (core thickness, edge thickness, etc.) required for the lenses constituting each lens group are satisfied. Not only will it be difficult to ensure this, but also the degree of freedom in design required for aberration correction cannot be ensured. On the contrary, when the value exceeds the upper limit of the conditional expression range (11), the thickness of each lens unit on the optical axis becomes too large, and a compact zoom lens system cannot be achieved.

Regarding the above conditions, it is more preferable to satisfy the following conditional expression range (11a) in the conditional expression range (11). 1 <max (T1, T2, T3) / fw <3 (11a) The zoom lens system of each embodiment has the following conditional expression range (1
It is desirable to satisfy the conditions specified in 2). 6 <Lw / fw <10 (12) where Lw is the total length of the optical system in the shortest focal length state (from the lens tip to the image plane).

The above conditions represent the telephoto ratio in the shortest focal length state. When the lower limit of conditional expression range (12) is exceeded,
The total length of the optical system becomes too small, making it difficult to correct aberrations.
Further, it becomes difficult to satisfy the substantially telecentric condition required for the photographing optical system for the digital camera. On the contrary, if the upper limit of conditional expression (12) is exceeded, compactness cannot be achieved. Furthermore, as the total length increases, the illuminance on the image plane can be secured, and the front lens diameter must be increased, which also makes it impossible to achieve a compact zoom lens system.

In the zoom lens system, the focal length is changed by changing the distance between the groups, in other words, changing the amount of magnification change (β) of each group. Therefore,
The lens group that has a large change in the amount of zooming that accompanies zooming contributes to that amount of zooming, which inevitably increases the aberration burden. Considering this, when trying to zoom efficiently, It is desirable that each group of the zoom lens system should bear the magnification variation as evenly as possible. When such a zoom load relationship is realized, the aberration load of each lens group is also equally distributed. Therefore, the configuration of the lens group of the zoom lens system depends on the configuration (that is, the number and size of components). ) Is considered to be optimized.

From the above viewpoints, it is desirable that the zoom lens system of each embodiment satisfies the condition defined by the following conditional expression range (13). 0.2 <Δβ3 / Δβ2 <1.0 (13) However, Δβ2: lateral magnification ratio of the second lens group (lateral magnification in the longest focal length state / lateral magnification in the shortest focal length state) Δβ3: lateral magnification of the third lens group The ratio (lateral magnification in the longest focal length state / lateral magnification in the shortest focal length state).

The above condition is a condition showing the variable magnification load of the second and third lens groups. In the conventionally known zoom lens system, the zooming load of the second lens group is large, but the zooming load of the third lens group is also shared, so that zooming can be performed efficiently. The system is shortened and the lens group configuration is reduced. Conditional expression range (1
When the value goes below the lower limit of 3), the zooming load of the third lens group decreases and the zooming load of the second lens group increases. Therefore, spherical aberration on the long focal length side tends to be under, and on the short focal length side. The distortion aberration also becomes large, and it becomes impossible to correct the aberration. On the contrary, if the upper limit of the conditional expression range (13) is exceeded, the third
Since the zooming load on the lens group increases, spherical aberration on the long focal length side falls to the over side, and off-axis coma aberration occurs on both the long focal length side and the short focal length side. It becomes impossible to do. In either case, it is impossible to sufficiently correct aberrations with this configuration, and it is inevitable to increase the number of components or increase the size of the lens system to increase the degree of freedom in design.

Regarding the above conditions, in the conditional expression range (13), the following conditional expression ranges (13a) to (1)
It is more desirable to satisfy 3c). 0.25 <Δβ3 / Δβ2 <1.0 (13a) 0.5 <Δβ3 / Δβ2 <1.0 (13b) 0.7 <Δβ3 / Δβ2 <1.0 (13c) Further, the zoom lens system of each embodiment has the following conditional expression range (14). It is desirable to satisfy the specified conditions. 3.5 <βT2 / βw2 <6.5 (14) where βT2 is the lateral magnification of the second lens group in the longest focal length state, and βw2 is the lateral magnification of the second lens group in the shortest focal length state.

The above conditions are conditions for defining the change in the lateral magnification of the second lens group during zooming, and also specify the zooming load of the second lens group. When the value exceeds the upper limit of the conditional expression range (14), the zooming load of the second lens group becomes too large, so that spherical aberration on the long focal length side tends to be under, and distortion aberration on the short focal length side also occurs. It becomes too large to correct aberration. On the other hand, when the value goes below the lower limit of the conditional expression range (14), the variable magnification load of the second lens group becomes small and the load of the other lens groups becomes large, so that the spherical aberration on the long focal length side becomes excessive. Not only is the lens tilted, but off-axis coma aberration increases on both the short focal length side and the long focal length side, which is not desirable.

4.5 <ft / | f12w | <15 (15) where ft: focal length in longest focal length state, f12w: combined focal length of first lens group and second lens group in shortest focal length state, .

The above condition is a condition for defining the combined focal length of the first lens unit and the second lens unit in the longest focal length state, and is a condition for achieving a compact and high magnification zoom lens. If the lower limit of the conditional expression range (15) is exceeded, the combined focal length of the first lens group and the second lens group on the short focal length side becomes too large, and it becomes difficult to secure the back focus. Further, the power of the first lens group or the second lens group becomes too weak, and it becomes impossible to achieve a compact zoom lens system. On the contrary, when the upper limit of the conditional expression range (15) is exceeded, the combined focal length of the first lens group and the second lens group on the short focal length side becomes too small, and it is difficult to correct the distortion aberration on the short focal length side. become. Further, the power of the first lens group or the second lens group becomes too strong, which makes it difficult to correct aberrations, which is not desirable.

In the zoom lens system of each embodiment, it is desirable that at least one aspherical surface satisfying the condition defined by the following conditional expression (16) is provided in the second lens group. -0.1 <φ × (N'-N) × d / dH {X (H) -X0 (H)} <0 (16) where φ: power of aspherical surface, N: of medium on the object side of the aspherical surface Refractive index for d-line, N ': Refractive index of the medium on the image side of the aspherical surface for d-line, H: Height in the direction perpendicular to the optical axis, X (H): Optical axis at height H of the aspherical surface Amount of displacement in the direction, X0 (H): Amount of displacement in the optical axis direction at the height H of the reference spherical surface.

Of the aspherical surfaces in the second lens group, the aspherical surface provided on the side relatively close to the object side is effective in correcting distortion on the short focal length side, and is provided on the surface close to the image side. The aspherical surface thus formed is effective for correcting spherical aberration on the long focal length side. The action of the aspherical surface is in the direction of weakening the paraxial power, and acts to weaken the aberration that is overcorrected by the configuration of only the spherical surface. In the case of the embodiment, when the power of the aspherical surface of the negative surface provided in the lens close to the object side in the second lens group becomes too strong, the negative distortion aberration at the short focal length side becomes too large, and When the negative power becomes weak, it is advantageous for correcting the distortion aberration on the short focal length side, but the spherical aberration on the long focal length side is undercorrected, and the optical performance cannot be secured. The same applies to the case where the positive power surface in the second lens group has an aspheric surface, and the same phenomenon occurs when the power of the positive surface in the second lens group becomes weak and when the negative power becomes strong. If the power of the aspherical surface provided on the positive surface of the lens relatively close to the image side of the second lens group becomes too weak, the spherical aberration on the long focal length side falls to the over side and the spherical aberration is corrected. It becomes an excessive state. vice versa,
If the power becomes too strong, the correction will be insufficient and neither is desirable.

In the zoom lens system of each embodiment, it is desirable that at least one aspherical surface satisfying the condition defined by the following conditional expression range (17) is included in the third lens group. -0.1 <φ × (N'-N) × d / dH {X (H) -X0 (H)} <0 (17) where φ: power of aspherical surface, N: of medium on the object side of the aspherical surface Refractive index for d-line, N ': Refractive index of the medium on the image side of the aspherical surface for d-line, H: Height in the direction perpendicular to the optical axis, X (H): Optical axis at height H of the aspherical surface Amount of displacement in the direction, X0 (H): Amount of displacement in the optical axis direction at the height H of the reference spherical surface.

Among the aspherical surfaces in the third lens group, the aspherical surface provided relatively on the object side is effective mainly for correcting spherical aberration on the short focal length side, and is a lens relatively close to the image plane side. Regarding the surface, it is effective for correcting the image surface property and flare on the long focal length side. In the third lens group, when an aspherical surface is provided in the direction close to the object side in which the positive power is weakened, if the power becomes too weak, the spherical aberration on the short focal length side will be undercorrected, and conversely If the power becomes too strong, spherical aberration will be overcorrected. In either case, it becomes difficult to correct the aberration by the optical system after that in either case, and as a result, an increase in the number of lenses or an increase in the size of the optical system cannot be avoided in order to correct the aberration. Also,
Regarding the aspherical surface in the third lens group, which is in the direction in which the negative power is weakened in the lens close to the image plane, if the negative power is too weak, the convergence of the off-axis rays on the long focal length side on the upper side deteriorates, Excessive flare occurs, and as a result the image quality deteriorates. On the short focal length side, the effect on off-axis rays becomes too strong and excessive negative distortion occurs. On the contrary, if the negative power becomes too strong, the off-axis rays on the short focal length side are affected, and the image surface property on the short focal length side deteriorates. The surface falls in the positive direction, and the aberration cannot be corrected on the other surfaces.

In each embodiment, it is desirable that the diaphragm be fixed during zooming. When the diaphragm is moved, it is necessary to secure a space for a cam device for moving the diaphragm, a lens barrel, a cam driving device, and the like, and an optical device incorporating this zoom lens system is becoming larger.

Further, in each embodiment, the aperture is set to the second position.
It is desirable to place it between the lens group and the third lens group. By arranging the diaphragm between the second lens group and the third lens group, it becomes possible to prevent a decrease in peripheral light amount in a balanced manner during zooming from the shortest focal length state to the intermediate focal length state.

Further, it is desirable that the open aperture diameter be constant during zooming. Normally, the aperture is open FNO
The circular aperture corresponding to is closed by opening and closing the diaphragm blades. Further, considering the influence on the image, it is desirable that the aperture shape of the open aperture be a circle. Therefore, in consideration of the influence on the image, if the open aperture diameter is different in each focal length state during zooming, the aperture is set by either using the aperture blades or arranging a plurality of circular apertures. You need to control it. However, in the case of the former diaphragm blade, a small number of diaphragm blades inevitably require a large number of blades of 5 or 6 in order to form a distorted opening shape and to approximate a circle, which inevitably results in an increase in cost. In addition, in the case of having a plurality of circular apertures like the latter, not only the cost increases, but also a space for inserting the circular apertures in the optical axis direction is required, which leads to an increase in size of the optical system.

[0059]

EXAMPLES Specific examples of the present invention will be described below with reference to construction data and aberration diagrams.

Examples 1 to 4 listed below correspond to the above-described embodiments, respectively, and the lens arrangement diagrams representing the embodiments show the lens configurations of the corresponding Examples 1 to 4, respectively.

In each embodiment, ri (i = 1, 2, 3 ...
・) Is the radius of curvature of the i-th surface counted from the object side, di (i =
1, 2, 3 ··· represents the i-th axial upper surface distance counted from the object side, and Ni (i = 1, 2, 3 ··), νi (i = 1, 2,
3 ...) indicates the refractive index and Abbe number for the d-line of the i-th lens counted from the object side. Further, f is the focal length of the entire system, and FNO is the F number. In each embodiment, the focal length f of the entire system, the F number FNO, and the air gap between the lens groups (axial upper face gap) are, in order from the left, the shortest focal length end (wide angle end) (W) and the middle. It corresponds to the respective values at the focal length (M) and the longest focal length end (telephoto end) (T).

Further, in each of the examples, the surface marked with the radius of curvature ri indicates that it is an aspherical refractive optical surface or a surface having a refractive action equivalent to that of an aspherical surface. Shall be defined by the following formula.

X (H) = CH ² / {1+ (1-ε · C ² · H ² ) ^1/2 } + ΣAi · Hi (AS) where H: height in the direction perpendicular to the optical axis , X (H): Amount of displacement in the optical axis direction at height H (reference to surface apex), C: Paraxial curvature, ε: Quadric surface parameter, Ai: i-th order aspherical coefficient, Hi: H Is a symbol that represents the i-th power of.

Example 1 f = 5.12 to 15.50 to 48.75 Fno = 2.73 to 4.31 to 4.10 [curvature radius] [axis upper surface spacing] [refractive index] [Abbe number] r1 = 34.255 d1 = 0.60 N1 = 1.847049 ν1 = 25.00 r2 = 24.307 d2 = 0.16 r3 = 24.992 d3 = 3.41 N2 = 1.487490 ν2 = 70.44 r4 = -114.984 d4 = 0.10 r5 = 20.927 d5 = 1.29 N3 = 1.565362 ν3 = 61.66 r6 = 31.362 d6 = 0.10 ~ 12.78 ~ 23.33 r7 = 17.176 d7 = 0.60 N4 = 1.847831 ν4 = 27.77 r8 = 5.655 d8 = 3.63 r9 = 22.850 d9 = 1.20 N5 = 1.798500 ν5 = 22.60 r10 = -13.011 d10 = 0.73 r11 * = -7.768 d11 = 0.75 N6 = 1.798500 ν6 = 22.60 r12 = -5.134 d12 = 0.60 N7 = 1.761352 ν7 = 50.41 r13 * = 12.571 d13 = 6.88 to 2.11 to 0.32 r14 = ∞ d14 = 3.00 to 2.00 to 0.10 r15 = 6.826 d15 = 1.12 N8 = 1.586416 ν8 = 59.98 r16 = 43.123 d16 = 0.10 r17 = 5.588 d17 = 2.84 N9 = 1.517966 ν9 = 66.40 r18 = -8.166 d18 = 0.35 r19 = -6.587 d19 = 1.09 N10 = 1.784209 ν10 = 29.06 r20 = 9.397 d20 = 1.80 r21 = 3.568 d21 = 1.30 N11 = 1.531829 ν11 = 64.85 r22 * = 8.075 d22 = 3.19 to 7.89 to 12.83 r23 = ∞ d23 = 3.70 N12 = 1.516800 ν12 = 64.20 r24 = ∞ [Non Surface coefficients] r11 ε = 1.0000 A4 = -8.09441 × 10 -4 A6 = -3.81431 × 10 -5 A8 = 2.03843 × 10 -5 A10 = -1.95474 × 10 -6 A12 = 6.29809 × 10 -8 r13 ε = 1.0000 A4 = -1.57384 × 10 ^-3 A6 = -3.00291 × 10 ^-5 A8 = 2.34322 × 10 ^-5 A10 = -2.90404 × 10 ^-6 A12 = 1.29620 × 10 ^-7 r22 ε = 1.0000 A4 = 6.06134 × 10 ^-3 A6 = 1.34 200 × 10 ^-5 A8 = 6.72 379 × 10 ^-5 A10 = -9.58951 × 10 ^-6 A12 = 7.15528 × 10 ^-7 << Example 2 >> f = 5.12 to 15.50 to 48.75 Fno = 2.26 to 2.77 to 4.10 [curvature radius] [Axis spacing] [Refractive index] [Abbe number] r1 = 53.711 d1 = 0.60 N1 = 1.798500 ν1 = 22.60 r2 = 27.004 d2 = 0.01 N2 = 1.514000 ν2 = 42.83 r3 = 27.004 d3 = 3.20 N3 = 1.754500 ν3 = 51.57 r4 = -1101.306 d4 = 0.10 r5 = 21.200 d5 = 1.97 N4 = 1.487490 ν4 = 70.44 r6 = 38.384 d6 = 0.10 to 13.58 to 20.46 r7 = 10.109 d7 = 0.60 N5 = 1.849967 ν5 = 39.77 r8 * = 5.358 d8 = 2.37 r9 =- 64.671 d9 = 0.60 N6 = 1.850000 ν6 = 40.04 r10 = 8.081 d10 = 0.10 r11 = 7.801 d11 = 1.90 N7 = 1.798500 ν7 = 22.60 r12 = -16.817 d12 = 1.03 r13 = -6.936 d13 = 0.60 N8 = 1.785779 ν8 = 46.80 r14 * = 130.561 d14 = 9.15 ~ 3.8 4 to 0.11 r15 = ∞ d15 = 0.82 to 0.89 to 0.10 r16 * = 8.023 d16 = 1.23 N9 = 1.674291 ν9 = 54.76 r17 = -62.203 d17 = 0.10 r18 = 5.569 d18 = 1.88 N10 = 1.487490 ν10 = 70.44 r19 = -28.528 d19 = 0.10 r20 = 10.643 d20 = 0.60 N11 = 1.844735 ν11 = 23.77 r21 = 3.803 d21 = 3.07 r22 = 6.438 d22 = 4.05 N12 = 1.553618 ν12 = 42.71 r23 * = 17.611 d23 = 1.05 ~ 4.20 ~ 10.46 r24 = ∞ d24 = 3.70 N13 = 1.516800 ν13 = 64.20 r25 = ∞ [aspheric coefficient] r8 ε = 1.0000 A4 = 6.46463 × 10 ^-6 A6 = 7.12987 × 10 ^-6 A8 = -1.62410 × 10 ^-6 A10 = 1.48107 × 10 ^-7 A12 = -4.68558 × 10 ^-9 r14 ε = 1.0000 A4 = -4.50773 × 10 ^-4 A6 = 1.11988 × 10 ^-5 A8 = -1.26713 × 10 ^-6 A10 = 7.63556 × 10 ^-8 A12 = 4.89912 × 10 ^-10 r16 ε = 1.0000 A4 = -6.88311 × 10 ^-4 A6 = -2.40885 × 10 ^-6 A8 = -1.07446 × 10 ^-6 A10 = 1.21996 × 10 ^-7 A12 = -5.39 814 × 10 ^-9 r23 ε = 1.0000 A4 = 7.43446 × 10 ^-4 A6 = 3.20186 × 10 ^-5 A8 = -1.13515 × 10 ^-5 A10 = 1.73213 × 10 ^-6 A12 = -9.08995 × 10 ^-8 << Example 3 >> f = 5.13 to 15.50 to 48.75 Fno = 2.73 to 4.31 to 4.10 (curvature Radius] [Space between upper surfaces] [Refractive index] [Abbe number] r1 = 56.851 d1 = 0.60 N1 = 1.839592 ν1 = 27.49 r2 = 23.446 d2 = 0.11 r3 = 23.446 d3 = 3.85 N2 = 1.567298 ν2 = 61.49 r4 = -317.865 d4 = 0.10 r5 = 21.360 d5 = 2.74 N3 = 1.754500 ν3 = 51.57 r6 = 50.308 d6 = 0.10 to 13.11 to 23.02 r7 = 10.549 d7 = 0.60 N4 = 1.622384 ν4 = 38.80 r8 = 4.002 d8 = 2.00 r9 = 14.422 d9 = 1.35 N5 = 1.798500 ν5 = 22.60 r10 = -15.568 d10 = 0.10 r11 * =-22.319 d11 = 1.35 N6 = 1.681782 ν6 = 27.64 r12 = -4.598 d12 = 0.60 N7 = 1.850000 ν7 = 40.04 r13 * = 7.695 d13 = 7.73 ~ 5.61 ~ 1.19 r14 = ∞ d14 = 2.84 ~ 0.20 ~ 0.10 r15 * = 3.880 d15 = 2.17 N8 = 1.487490 ν8 = 70.44 r16 = -35.992 d16 = 0.33 r17 = 9.979 d17 = 1.98 N9 = 1.487490 ν9 = 70.44 r18 = -7.299 d18 = 0.15 r19 = -6.274 d19 = 2.67 N10 = 1.846836 ν10 = 24.34 r20 = -22.235 d20 = 0.22 r21 * =-49.128 d21 = 3.47 N11 = 1.527547 ν11 = 63.51 r22 * = 16.004 d22 = 0.52 〜 3.16 〜 3.25 r23 = ∞ d23 = 3.70 N12 = 1.516800 ν12 = 64.20 r24 = ∞ [aspheric coefficient] r11 ε = 1.0000 A4 = -1.516 49 × 10 ^-3 A6 = 2.66548 × 10 ^-5 A8 = 1.22282 × 10 ^-5 A10 = -1.32 300 × 10 ^-6 A12 = 4.92614 × 10 ^-8 r13 ε = 1.0000 A 4 = -3.23885 × 10 ^-3 A6 = 3.40371 × 10 ^-5 A8 = 2.06254 × 10 ^-5 A10 = -3.68376 × 10 ^-6 A12 = 2.02326 × 10 ^-7 r15 ε = 1.0000 A4 = -1.12558 × 10 ^-3 A6 = -8.48960 × 10 ^-5 A8 = 3.21273 × 10 ^-6 A10 = -1.83274 × 10 ^-7 A12 = -3.06639 × 10 ^-8 r21 ε = 1.0000 A4 = -7.38365 × 10 ^-3 A6 = -2.15053 × 10 ^-4 A8 = -9.38824 x 10 ^-5 A10 = 9.96727 x 10 ^-6 A12 = -1.04625 x 10 ^-6 r22 ε = 1.0000 A4 = -3.78 250 x 10 ^-3 A6 = -2.14667 x 10 ^-4 A8 = 6.93245 x 10 ^-5 A10 = -1.13196 × 10 ^-5 A12 = 7.18551 × 10 ^-7 《Embodiment 4》 f = 5.10 to 16.01 to 48.80 Fno = 3.10 to 3.60 to 4.20 [radius of curvature] [axis upper surface interval] [refractive index] [Abbe number ] r1 = 51.316 d1 = 0.60 N1 = 1.818759 ν1 = 23.23 r2 = 21.286 d2 = 2.15 N2 = 1.642484 ν2 = 56.38 r3 = -145.048 d3 = 0.10 r4 = 16.706 d4 = 1.36 N3 = 1.754500 ν3 = 51.57 r5 = 35.177 d5 = 0.50 ~ 7.83 ~ 15.62 r6 * = 24.341 d6 = 0.60 N4 = 1.713476 ν4 = 53.06 r7 * = 6.094 d7 = 3.72 r8 = -5.140 d8 = 0.22 N5 = 1.697627 ν5 = 53.71 r9 = 9.515 d9 = 0.75 N6 = 1.813453 ν6 = 22.98 r10 = -31.907 d10 = 10.45 to 4.50 to 0.40 r11 = ∞ d11 = 0.10 r12 * = 4.781 d12 = 1.33 N7 = 1.727475 ν7 = 46.05 r13 = -35.839 d13 = 0.10 r14 = 239.202 d14 = 2.25 N8 = 1.755000 ν8 = 27.60 r15 = 4.906 d15 = 0.10 r16 = 5.581 d16 = 0.22 N9 = 1.747052 ν9 = 38.08 r17 = 2.897 d17 = 1.40 N10 = 1.487000 ν10 = 70.40 r18 = 32.525 d18 = 0.84 r19 * = 6.428 d19 = 0.69 N11 = 1.532956 ν11 = 51.14 r20 = 33.260 d20 = 1.38 ~ 6.57 ~ 5.88 r21 = ∞ d21 = 3.40 N12 = 1.516800 ν12 = 64.20 r22 = ∞ [ Aspherical coefficient] r6 ε = 1.0000 A4 = 1.19413 × 10 ^-3 A6 = -5.05252 × 10 ^-5 A8 = 2.33263 × 10 ^-6 A10 = -7.39707 × 10 ^-8 A12 = 1.22559 × 10 ^-9 r7 ε = 1.0000 A4 = 1.12929 × 10 ^-3 A6 = -2.79368 × 10 ^-5 A8 = 2.71069 × 10 ^-6 A10 = -2.07291 × 10 ^-7 A12 = 5.55089 × 10 ^-9 r12 ε = 1.0000 A4 = -7.09501 × 10 ^-4 A6 = -1.37096 x 10 ^-5 A8 = -2.327 13 x 10 ^-6 A10 = 7.09276 x 10 ^-8 r19 ε = 1.0000 A4 = -9.92974 x 10 ^-4 A6 = 1.23299 x 10 ^-5 A8 = 1.61718 x 10 ^-6 A10 = 3.97318 × 10 ⁻⁷ FIGS. 5 to 8 are aberration diagrams corresponding to Examples 1 to 4. Each aberration diagram shows a spherical aberration diagram, an astigmatism diagram, and a distortion diagram in order from the left side. Further, each aberration diagram shows, in order from the top, aberrations of the optical system corresponding to the above-mentioned shortest focal length state (wide-angle end), intermediate focal length state, and longest focal length state (telephoto end).

In each spherical aberration diagram, the solid line d represents the spherical aberration amount for the d line, the dash-dotted line g represents the spherical aberration amount for the g line (Example 3 only), and SC represents the sine condition dissatisfaction amount. In each astigmatism diagram, the solid line DS represents the sagittal surface and the dotted line DM represents the meridional surface. The vertical axis of the spherical aberration diagram represents the F number of the light beam, and the vertical axes of the astigmatism diagram and the distortion diagram represent the maximum image height Y '.

The values corresponding to the conditional expressions of each embodiment are shown below. In each data, the letter E after the number indicates the exponent part.For example, 1.0E-2 is 1.0 × 10 ^-2
Shall be represented. In addition, the condition (16) and the condition (1
In 7), the height represents the distance (mm) in the direction perpendicular to the optical axis, and No. 10 corresponds to the maximum effective diameter.

Example 1 (1) f1 / flw: 8.48 (2) f2 / flw: -1.07 (3) f3 / flw: 1.55 (4) img × R: 7.86 (5) Ra / f3: 0.80 ( 6) R2n / f2: -1.03 (6) 'f2p / f2: -1.92 (7) νn: 25.00 (8) νp: 70.44,61.66 (9) m1 / Z: 2.46 (10) M1WM / M1MT: 0.98 (11) ) Max (T1, T2, T3) / flw: 1.68 (12) Lw / flw: 7.80 (13) Δβ3 / Δβ2: 0.790 (14) βT2 / βw2: 3.47 (15) ft / | f12w |: 6.66 (16) φ × (N'-N) × d / dH {X (H) -X0 (H)} r11 No Height value 1 0.3557 0.1206E-04 2 0.7115 0.9798E-04 3 1.0672 0.3307E-03 4 1.4230 0.7526E -03 5 1.7787 0.1327E-02 6 2.1345 0.1931E-02 7 2.4902 0.2446E-02 8 2.8459 0.2890E-02 9 3.2017 0.3121E-02 10 3.5574 0.9253E-03 r13 No Height value 1 0.2798-0. 6375E-05 2 0.5597 -0.5121E-04 3 0.8395 -0.1730E-03 4 1.1194 -0.4062E-03 5 1.39 2 -0.7737E-03 6 1.6791 -0.1280E-02 7 1.9589 -0.1917E-02 8 2.2388 -0.2672E-02 9 2.5186 -0.3528E-02 10 10. 7985-0.4352E-0
2 (17) φ × (N′−N) × d / dH {X (H) -X0 (H)} r22 No Height value 1 0.2534 0.1382E-04 2 0.5067 0.1107E-03 3 0.7601 0.3761E-03 4 1.0134 0.9042E-03 5 1.2668 0.1810E-02 6 1.5201 0.3244E-02 7 1.7735 0.5408E-02 8 2.0268 0.8589E-02 9 2.2802 0.1329E-01 10 2.5335 0.2059E-01 << Example 2 >> (1) f1 / flw: 7.96 (2) f2 / flw: -1.07 (3) f3 / flw: 1.47 (4) img × R: 8.77 (5) Ra / f3: 1.07 (6) R2n / f2: -1.01 (6) 'f2p / f2: ---- (7) νn: 22.60 (8) νp: 42.83,51.57 (9) m1 / Z: 2.11 (10) M1WM / M1MT: 1.32 (11) max (T1, T2, T3) / flw: 2.15 (12) Lw / flw: 7.96 (13) Δβ3 / Δβ2: 0.870 (14) βT2 / βw2: 3.31 (15) ft / | f12w |: 6.33 (16) φ × (N'-N) × d / dH {X (H) -X0 (H)} r8 No Height value 1 0.4280 0.3517E-06 2 0.8560 0.4295E-05 3 1.2840 0.1921E-04 4 1.7120 0.4923E-04 5 2.1400 0.8826E-04 6 2.5680 0.1401E-03 7 2.9960 0.2507E-03 8 3.4240 0.3569E-03 9 3.8520 -0.6708E-03 10 4.2800 -0.8220E-02 r14 No Height value 1 0.3070 -0.2459E-06 2 0.6140 -0.1948E-05 3 0.9210 -0.6476E-05 4 1.2280 -0.1508E-04 5 1.5350 -0.2892E-04 6 1.8420 -0.4910E-04 7 2.1490 -0.7656E -04 8 2.4560 -0.1115E-03 9 2.7630 -0.1517E-03 10 3.0700 -0.1895E-03 (17) φ × (N'-N) × d / dH {X (H) -X0 (H)} r16 No Height value 1 0.3370 -0.5975E-05 2 0.6740 -0.4791E-04 3 1.0110 -0.1625E-03 4 1.3480 -0.3888E-03 5 1.6850 -0.7699E-03 6 2.0220 -0.1354E-02 7 2.3590 -0.2196 E-02 8 2.6960 -0.3359E-02 9 3.0330 -0.4945E-02 10 3.3700 -0.7194E-02 r23 No Height value 1 0.2830 0.1179E-05 2 0.5660 0.9551E-05 3 0.8490 0.3271E-04 4 1.1320 0.7834 E-04 5 1.4150 0.1535E-03 6 1.6980 0.2646E-03 7 1.9810 0.4201E-03 8 2.2640 0.6324E-03 9 2.5470 0.9092E-03 10 2.8300 0.1202E-02 << Example 3 >> (1) f1 / flw : 7.50 (2) f2 / flw: -1.08 (3) f3 / flw: 1.29 (4) img × R: 7.8 (5) Ra / f3: 0.58 (6) R2n / f2: -0.72 (6) 'f2p / f2: -1.72 (7) νn: 27.49 (8) νp: 61.49 (9) m1 / Z: 1.64 (10) M1WM / M1MT: 1.99 (11) max (T1, T2, T3) / flw: 2.15 (12) Lw / flw: 7.80 (13) Δβ3 / Δβ2: 0.276 (14) βT2 / βw2: 5.87 (15) ft / | f12w |: 6.30 ( 16) φ × (N'-N) × d / d H {X (H) -X0 (H)} r11 No Height value 1 0.3294 0.4503E-05 2 0.6589 0.3562E-04 3 0.9883 0.1172E-03 4 1.3178 0.2648E-03 5 1.6472 0.4788E-03 6 1.9767 0.7397E-03 7 2.3061 0.1013E-02 8 2.6355 0.1255E-02 9 2.9650 0.1388E-02 10 3.2944 0.1131E-02 r13 No Height value 1 0.2609 -0.2158E -04 2 0.5218 -0.1719E-03 3 0.7827 -0.5752E-03 4 1.0436 -0.1343E-02 5 1.3045 -0.2562E-02 6 1.5654 -0.4292E-02 7 1.8263 -0.6580E-02 8 2.0872 -0.9480E- 02 9 2.3481 -0.1306E-01 10 2.6089 -0.1722E-01 (17) φ × (N'-N) × d / d H {X (H) -X0 (H)} r15 No Height value 1 0.3069 -0.8057 E-05 2 0.6138 -0.6645E-04 3 0.9208 -0.2351E-03 4 1.2277 -0.5916E-03 5 1.5346 -0.1238E-02 6 1.8415 -0.2316E-02 7 2.1484 -0.4041E-02 8 2.4554 -0.6824E -02 9 2.7623 -0.1156E-01 10 3.0692 -0.2027E-01 r21 No Height value 1 0.2267 0.1954E-05 2 0.4534 0.1575E-04 3 0.6801 0.5397E-04 4 0.9068 0.1312E-03 5 1.1336 0.2662E-03 6 1.3603 0.4849E-03 7 1.5870 0.8255E-03 8 1.8137 0.1346E-02 9 2.0404 0.2142E-02 10 2.2671 0.3382E-02 r22 No Height value 1 0.2679 -0.5091 E-05 2 0.5359 -0.4136E-04 3 0.8038 -0.1423E-03 4 1.0718 -0.3433E-03 5 1.3397 -0.6782E-03 6 1.6077 -0.1180E-02 7 1.8756 -0.1882E-02 8 2.1436 -0.2822E -02 9 2.4115 -0.3966E-02 10 2.6794 -0.4941E-02 << Example 4 >> (1) f1 / flw: 5.39 (2) f2 / flw: -0.92 (3) f3 / flw: 1.56 (4) img × R: 8.65 (5) Ra / f3: 0.60 (6) R2n / f2: -1.28 (6) 'f2p / f2: ---- (7) νn: 23.23 (8) νp: 56.38,51.57 (9) m1 / Z: 1.01 (10) M1WM / M1MT: 2.19 (11) max (T1, T2, T3) / flw: 2.15 (12) Lw / flw: 7.84 (13) Δβ3 / Δβ2: 0.33 (14) βT2 / Βw2: 5.38 (15) ft / | f12w |: 6.96 (16) φ × (N'-N) × d / d H {X (H) -X0 (H)} r6 No Height value 1 0.4835 0.1113E- 04 2 0.9670 0.8527E-04 3 1.4505 0.2690E-03 4 1.9341 0.5852E-03 5 2.4176 0.1038 E-02 6 2.9011 0.1624E-02 7 3.3846 0.2347E-02 8 3.8681 0.3241E-02 9 4.3516 0.4473E-02 10 4.8352 0.6691E-02 r7 No Height value 1 0.3774 0.2017E-04 2 0.7547 0.1590E-03 3 1.1321 0.5252E-03 4 1.5094 0.1214E-02 5 1.8868 0.2307E-02 6 2.2641 0.3872E-02 7 2.6415 0.5938E-02 8 3.0188 0.8459E-02 9 3.3962 0.1134E-01 10 3.7735 0.1472E-01 (17 ) Φ × (N'-N) × d / dH {X (H) -X0 (H)} r12 No Height value 1 0.3002 -0.8522E-05 2 0.6004 -0.6876E-04 3 0.9006 -0.2358E-03 4 1.2008 -0.5737E-03 5 1.5011 -0.1164E-02 6 1.8013 -0.2120E-02 7 2.1015 -0.3599E-02 8 2.4017 -0.5820E-02 9 2.7019 -0.9071E-02 10 3.0021 -0.1369E-01 r19 No Height value 1 0.2752 -0.3652E-05 2 0.5504 -0.2909E-04 3 0.8256 -0.9732E-04 4 1.1008 -0.2273E-03 5 1.3759 -0.4326E-03 6 1.6511 -0.7148E-03 7 1.9263 -0.1047 E-02 8 2.2015 -0.1347E-02 9 2.4767 -0.1419E-02 10 2.7519 -0.8695E-03

[0068]

As described above in detail, according to the zoom lens device of the present invention, it is possible to provide a zoom lens device having a compact zoom lens system despite having a high zoom ratio and high image quality. can do.

Therefore, when the zoom lens device according to the present invention is applied to a digital camera, it can contribute to high functionality and compactness of the camera.

[Brief description of drawings]

FIG. 1 is a lens configuration diagram of a zoom lens system according to a first embodiment.

FIG. 2 is a lens configuration diagram of a zoom lens system according to a second embodiment.

FIG. 3 is a lens configuration diagram of a zoom lens system according to a third embodiment.

FIG. 4 is a lens configuration diagram of a zoom lens system according to a fourth embodiment.

FIG. 5 is an aberration diagram of the zoom lens system according to the first embodiment.

FIG. 6 is an aberration diagram of a zoom lens system according to a second embodiment.

FIG. 7 is an aberration diagram of a zoom lens system according to a third embodiment.

FIG. 8 is an aberration diagram of a zoom lens system according to a fourth embodiment.

[Explanation of symbols]

Gr1: first lens group Gr2: Second lens group Gr3: Third lens group

Front page continuation (72) Inventor Mamoru Terada 2-3-13 Azuchi-cho, Chuo-ku, Osaka City Osaka Osaka Building Minolta Co., Ltd. (72) Tetsuya Arimoto 2-3-3 Azuchi-cho, Chuo-ku, Osaka No. Osaka International Building Minolta Co., Ltd. (72) Inventor Naoshi Okada 2-3-3 Azuchi-cho, Chuo-ku, Osaka City Osaka Osaka Building Minolta Co., Ltd. (56) Reference JP-A 1-271717 (JP, A) JP-A-7-63993 (JP, A) JP-A-6-347698 (JP, A) JP-A-4-56816 (JP, A) JP-A-2-39116 (JP, A) JP-A-3 -15014 (JP, A) JP-A-4-95911 (JP, A) JP-A-4-253017 (JP, A) JP-A-4-294311 (JP, A) JP-A-4-317019 (JP, A) ) JP-A-4-317020 (JP, A) JP-A-5-173068 (JP, A) JP-A-7-27977 (JP, A) JP-A-7-63992 (JP, A) JP-A-63- 189819 (JP, A) 63-133113 (JP, A) JP-A 63-133114 (JP, A) JP-A 58-88717 (JP, A) JP-A 63-118117 (JP, A) JP-A 63-118116 (JP, A) JP 61-176906 (JP, A) JP 61-83514 (JP, A) JP 60-191219 (JP, A) JP 57-40220 (JP, A) JP 61 -177412 (JP, A) JP 61-259217 (JP, A) JP 61-264313 (JP, A) JP 62-244012 (JP, A) JP 63-298210 (JP, A) ) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02B 15/16

Claims (3)

(57) [Claims] 1. A zoom lens system comprising, in order from the object side, a zoom lens system and a solid-state image sensor for receiving an optical image formed by the zoom lens system, wherein the zoom lens system is the object side. In order from the first lens group having positive power, the second lens group having negative power, and the third lens group having positive power, at least the first lens group is moved to perform zooming. The first lens group includes, in order from the object side, a negative lens, a positive lens, and a positive lens, and the third lens group satisfies the condition (17) of an aspherical surface or less.
Having at least one aspherical surface satisfying the following condition (9) : 0.7 <m1 / Z <3.0 (9) -0.1 <φ × (N'-N) × d / dH {X (H)-X0 (H)} <0
(17) However, m1: movement amount (mm) when zooming from the shortest focal length state of the first lens group to the longest focal length state, Z: zoom ratio (Z = ft / fw: shortest focal length state and longest focal length state) (Focal length ratio in focal length state), φ: power of aspherical surface, N: refractive index of d-line of medium on the object side of the aspherical surface, N ′: refractive index of d-line of medium of aspherical surface on the image side, H : Height in the direction perpendicular to the optical axis, X (H): Displacement in the optical axis direction at the height H of the aspherical surface , X0 (H): Displacement in the optical axis direction at the height H of the reference spherical surface , . 2. In zooming, the distance between the first lens group and the second lens group on the optical axis is increased, and the distance between the second lens group and the third lens group is decreased. The zoom lens device according to claim 1, wherein the first lens unit and the third lens unit move toward the object side. 3. The zoom lens apparatus according to claim 2, wherein the second lens group moves during zooming.