JPH11109236A - Zoom lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens system compact in structure although it satisfys a high variable power ratio and high image quality. SOLUTION: In this zoom lens system composed, in order from the object side, of a first lens group Gr1 having a positive power, a second lens group Gr2 having a negative power, a third lens group Gr3 having a positive power and performing zooming operation by moving at least the first lens group, the first lens group includes a negative lens, a positive lens and a positive lens in order from the object side and the condition: 0.7<ml/Z<3.0 is satisfied, where, ml: the moving amount (mm) of the first lens at the time of zooming from the state of the shortest focal distance to the state of the longest focal distance and Z: zooming ratio (Z=ft/fw: the ratio of focal distance in the state of the shortest focal distance to the state of the longest focal distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens system used for a small photographing optical system.
The present invention relates to a compact and high-magnification zoom lens system suitable for a photographing optical system of a digital input / output device such as a digital still camera and a digital video camera.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and the like, digital still cameras, digital video cameras, and the like (hereinafter, simply referred to as digital cameras) that can easily capture image information into digital devices have spread at the individual user level. It is getting. Such digital cameras are expected to be increasingly used as image information input devices in the future.

In general, the image quality of a digital camera is determined by the number of pixels of a solid-state imaging device such as a CCD (charge coupled device). At present, the mainstream of digital cameras for general use is a so-called VGA class solid-state imaging device having about 330,000 pixels. However, the image quality of this VGA class camera is inferior to the image quality of a camera using a conventional silver halide film. For this reason,
Recently, high quality digital cameras having more than one million pixels have been demanded in general digital cameras, and it is required that the photographic optical system of these digital cameras also satisfy high quality.

In these digital cameras for general use, it is also desired to perform image scaling, particularly optical zooming with little image degradation. A zoom lens system has been required.

[0005]

However, in a zoom lens system for a digital camera which has been conventionally proposed, a 10
Those satisfying high image quality exceeding 0,000 pixels were mostly those using an interchangeable lens for a single-lens reflex camera or very large digital cameras for business use. Therefore, such a zoom lens system is very large and expensive, and cannot be said to be suitable for a digital camera for general use.

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

However, when the photographing optical system of the lens shutter camera is diverted to a digital camera as it is,
The light-gathering performance of the microlens provided on the front of the solid-state imaging device provided in the digital camera cannot be sufficiently satisfied, and the brightness of the image in the central part and peripheral part of the image changes extremely. This causes a problem. This is a problem that occurs because the exit pupil of the imaging optical system of the lens shutter camera is located near the image plane, and the off-axis light flux emitted from the imaging optical system is obliquely incident on the image plane. . In order to solve this problem, if the position of the exit pupil of the photographing optical system of the conventional lens shutter camera is to be moved away from the image plane, it is inevitable that the entire photographing optical system will become larger.

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

[0009]

In order to achieve the above object, a zoom lens system according to claim 1 comprises, in order from the object side, a first lens group having a positive power and a second lens group having a negative power. A zoom lens system having a group and a third lens group having a positive power and performing zooming by moving at least the first lens group, wherein the first lens group is negative in order from the object side. It includes a lens, a positive lens, and a positive lens, and satisfies the following conditions.

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. In this specification, “power” refers to an amount defined by the reciprocal of the focal length, and its deflecting action is caused not only by deflection on surfaces of media having different refractive indexes but also by deflection due to diffraction. It also includes deflection due to the refractive index distribution in the medium.

FIGS. 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 according to 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 stop S, and a positive refractive power. The zoom lens system includes a third lens group Gr3 and a low-pass filter LF. When zooming from the shortest focal length end to the longest focal length end, the distance between the first lens group and the second lens group increases, The first lens group and the third lens group are arranged such that the distance between the lens group and the third lens group is reduced.
This is a zoom lens system in which a lens group moves. The arrows attached in the drawing schematically represent the movement trajectories of the lens groups Gr1 to Gr3, the aperture S, and the low-pass filter LF during zooming from the shortest focal length state to the longest focal length state.

The zoom lens system according to the first embodiment includes, in order from the object side, a negative meniscus lens L1 convex to the object side;
A first lens unit Gr1 including a biconvex positive lens L2 and an object-side positive meniscus lens L3; an object-side negative meniscus lens L4; a biconvex positive lens L5; Lens L1 of the meniscus lens (front surface is aspherical) L6 and the biconcave negative lens (rear surface is aspherical) L7
The second lens group Gr2, the stop S, the object side convex positive meniscus lens L8, the biconvex positive lens L9, the biconcave negative lens L10, and the object side convex positive meniscus lens (rear surface Is an aspheric surface) L11
r3 and a low-pass filter F. During zooming from the shortest focal length state to the longest focal length state, the first lens unit Gr1, the third lens unit Gr3, and the stop S move to the object side, and the second lens unit Gr2 moves once to the object side and then moves to the image side. U-turn so as to move to the side, and the low-pass filter F is fixed.

The zoom lens system according to the second embodiment includes, in order from the object side, a cemented lens DL1 of a negative meniscus lens L1 convex on the object side and a biconvex positive lens L2, and a positive meniscus lens L3 convex on the object side. First lens group Gr composed of
1. Negative meniscus lens convex on the object side (aspherical front surface)
L4, a biconcave negative lens L5, and a biconvex positive lens L6
And a negative meniscus lens (the rear surface is aspheric) L convex on the image side.
7, a stop S, a biconvex positive lens (front surface is an aspheric surface) L8, a negative meniscus lens L9 convex on the object side, and a positive meniscus lens convex on the object side (rear surface). Is an aspheric surface) L10 and a third lens unit Gr
And a low-pass filter F. During zooming from the shortest focal length state to the longest focal length state, the first lens unit Gr1, the third lens unit Gr3, and the stop S
Moves to the object side, the second lens group Gr2 makes a U-turn so as to move to the image side once after moving to the object side, and the low-pass filter F is fixed.

The zoom lens system according to the third embodiment includes, in order from the object side, a negative meniscus lens L1 convex to the object side;
A first lens group Gr including a positive meniscus lens L2 convex on the object side and a positive meniscus lens L3 convex on the object side
1. Negative meniscus lens L4 convex on the object side, positive lens L5 biconvex, and positive meniscus lens L6 convex on the image side
A second lens group Gr including a cemented lens DL1 with a front surface having an aspheric surface and a biconcave negative lens L7 (a rear surface having an aspheric surface).
2. A stop S, a biconvex positive lens L8 (front surface is aspheric),
A biconvex positive lens L9, a negative meniscus lens L10 convex on the object side, and a negative meniscus lens L11 convex on the image side
And a third lens unit Gr3 including a biconcave negative lens L12 (both aspheric 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 toward the object side, the second lens group Gr2 moves toward the image side, and the stop S and the low-pass filter. F is fixed.

The zoom lens system according to the fourth embodiment includes, in order from the object side, a cemented lens DL1 of a negative meniscus lens L1 convex on the object side and a biconvex positive lens L2, and a positive meniscus lens L3 convex on the object side. First lens group Gr composed of
1. Negative meniscus lens convex on the object side (aspherical front surface)
L4, a second lens unit Gr2 composed of a cemented lens DL2 of a biconcave negative lens L5 and a biconvex positive lens L6, a stop S, a biconvex positive lens (front side is aspheric) L7, and a convex on the object side , 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 (aspherical front side) The third consisting of L11
It comprises 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
r3 and the stop S integral 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.

Hereinafter, conditions to be satisfied by the zoom lens system of each embodiment will be described. It is not necessary to satisfy all of the following conditions at the same time. It is desirable that the zoom lens system of each embodiment satisfies 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 condition is a condition for regulating the focal length of the first lens group. If the upper limit of the conditional expression range (1) is exceeded, the focal length of the first lens group becomes too large, and the amount of movement 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. Conversely, when the value goes below the lower limit of the conditional range (1), the power of the first lens unit increases, and the aberration generated in the first lens unit, particularly the spherical aberration on the long focal length side, increases. It is not preferable because good optical performance cannot be obtained.

Regarding the above conditions, the following conditional expression ranges (2a) to (1c) of the conditional expression range (1)
It is more desirable to satisfy the following order. 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 condition is a condition for regulating the focal length of the second lens group. If the lower limit value of the conditional expression range (2) is exceeded, the focal length of the second lens unit will be short, and the axial distance between the second lens unit and the third lens unit in the shortest focal length state will be large. The total length of the distance state becomes excessive. As a result, the lens diameters of the lenses included in the first lens group and the second lens group are undesirably increased. vice versa,
When the value exceeds the upper limit of the conditional expression range (2), the power of the second lens unit becomes large, and the aberration generated in the second lens unit, in particular, the Petzval sum becomes negative and the whole Petzval sum becomes excessively negative. This is not preferable because good optical performance cannot be obtained as a whole due to the large size.

Regarding the above conditions, the following conditional expression ranges (2a) to (2b) of the conditional expression range (2)
It is more desirable to satisfy the following order. -1.3 <f2 / fw <-0.8 (2a) -1.4 <f2 / fw <-0.8 (2b) The zoom lens system of each embodiment should 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 condition is a condition for regulating the focal length of the third lens group. When the value exceeds the upper limit of conditional expression range (3), the focal length of the third lens group becomes too large.
The overall length in the longest focal length state becomes too large, so that a compact zoom lens system cannot be obtained. Conversely, when the value goes below the lower limit value of the conditional expression range (3), the power of the third lens unit increases, and aberrations generated in the third lens unit, especially coma aberration, increase. The correction cannot be performed even if an aspherical surface is provided at any of the above-mentioned positions, and as a result, good optical performance cannot be obtained as a whole, which is not desirable.

With respect to the above condition, it is more preferable that the following conditional expression range (3a) among conditional expression range (3) is satisfied. 1.8 <f3 / fw <1.9 (3a) It is desirable that the zoom lens system according to each embodiment satisfies the condition defined by the following conditional expression range (4). 1.0 <img × R <15.0 (4) Where, img: Maximum image height (unit: mm), R: Effective lens surface located closest to the image side, excluding filters, etc., of the lens surfaces that compose the zoom lens system Diameter (unit: mm).

The above conditions are conditions for balancing the size of the zoom lens diameter and the correction of various aberrations with the conditions specific to the photographing optical system for a digital camera. In general, in a photographing optical system used for a digital camera using a solid-state imaging device, an incident light beam is converted into a light beam of the microlens in order to sufficiently satisfy the light-collecting performance of a microlens provided in front of the solid-state imaging device. Need to be made substantially perpendicular to the light. Therefore, a photographing optical system for a digital camera is required to be substantially telecentric on the image side in addition to correcting various aberrations in the same manner as a photographing optical system of a normal silver halide film camera. When the value exceeds the upper limit of conditional expression range (4), it becomes unnecessary for the zoom lens system to be substantially telecentric on the image side, and various aberrations, especially negative distortion on the short focal length side become too large. It becomes difficult to correct,
Undesirably, the inclination of the image surface toward the under side becomes remarkable.
Conversely, when the value exceeds the lower limit of the conditional expression range (4), it is difficult to satisfy substantially telecentricity, which is not desirable. In particular, if an attempt is made 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, which leads to an increase in the size of the optical system, which is not desirable.

Regarding the above condition, it is more preferable to satisfy the following conditional expression range (4a) out of the conditional expression range (4). 6.5 <img × R <9.5 (4a) Like the zoom lens system of each embodiment, a first lens group having a positive power, a second lens group having a negative power, and a positive A third lens group having power, a third lens group
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 such a configuration, various aberrations can be satisfactorily corrected.

For the positive lens provided closest to the object side in the third lens group, the following conditional expression range (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 of the third lens group, and f3 is the focal length of the third lens group.

The above condition defines the ratio between the radius of curvature of the image side surface of the positive lens disposed closest to the object side of the third lens unit and the focal length of the third lens unit. This is a condition relating to aberration correction ability. Conditional expression range (5)
Exceeds the upper limit, the curvature of the image side surface of the positive lens becomes too weak, and the tendency of spherical aberration to flow to the over side is undesirably increased. Conversely, if the lower limit of the conditional expression range (5) is exceeded, the curvature of the image side surface of the positive lens becomes too strong, and the spherical aberration tends to fall to the under side, which is not desirable.
If the lower limit value of the conditional expression range (5) is exceeded, the radius of curvature of the image side surface of the positive lens becomes too small, which makes the manufacturing difficult, which is not desirable.

As in the zoom lens system of each embodiment, in order from the object side, a first lens group having positive power, a second lens group having negative power, and a third lens group having positive power In the zoom lens system including: a second lens group including, in order from the object side, a second lens group first sub-group including a lens having a concave surface with a strong curvature directed to the image side; It is preferable that the second lens group and the second sub-group include one positive lens and one negative lens. By configuring the second lens unit in this manner, when the light beam is emitted from the concave surface having a strong curvature in the first sub-unit of the second lens unit, the emission angle of the off-axis light beam, particularly on the short focal length side, Since the exit angle of the on-axis light beam is reduced, it is possible to easily correct the aberration of the second lens unit and the second sub-unit and thereafter.

It is preferable 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 stipulates the ratio between the radius of curvature of the concave surface of the second lens group and the first sub group having a strong curvature and the focal length of the second lens unit, and the condition relating to the aberration correction capability of the concave surface. It is. If the lower limit value of the conditional expression range (6) is exceeded, the curvature of the concave surface becomes too weak, and the above-mentioned effect, that is, the angle of emergence of the off-axis light beam when the light beam entering the concave surface exits from the concave surface and the axis The effect of reducing the exit angle of the upper ray cannot be sufficiently achieved. As a result, if the lower limit value of the conditional expression range (6) is exceeded, the light rays emitted from the first sub-group of the second lens group are emitted to the succeeding group while the angle between the off-axis ray and the on-axis ray is large. , Aberrations at the image plane,
In particular, the curvature of field and coma cannot be corrected by the succeeding lens 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 is generated alone on the concave surface. Impossible and undesirable. If the value exceeds the upper limit of the conditional expression range (6), the radius of curvature of the concave surface becomes too small, which makes the manufacturing difficult, which is not desirable.

Further, the second sub-group of the second lens unit includes, in order from the object side, a biconvex positive single lens, and a positive lens having a convex surface on the image side and a biconcave negative lens joined together. And a cemented lens. The second lens group has negative power as a whole, but when chromatic aberration is corrected in the second lens group, at least one positive lens and at least one negative lens are provided in the second lens group. Must include a lens. On the other hand, since the second lens group first sub-group has a concave surface having a strong curvature on the image side as described above, the second lens group first sub-group is also required to achieve the effect of this concave surface. Cannot use a positive lens having a strong power for correcting chromatic aberration generated on the concave surface. Therefore, in order to correct the chromatic aberration of the entire second lens unit, the second sub-unit of the second lens unit 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 obtained by joining the two.

It is preferable that the positive lens in 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 in 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 in the second sub-group of the second lens unit and the focal length of the second lens unit, and is a condition relating to chromatic aberration correction of the second lens unit. is there. If the lower limit value of the conditional expression range (6) ′ is exceeded, the power of the positive lens becomes too weak, and the chromatic aberration generated in the second lens group becomes undesirably large. On the other hand, when the value exceeds the upper limit of conditional expression range (6) ′, the power of the positive lens becomes too strong, and the power of the negative lens included in the second lens group must be increased to correct the chromatic aberration of the second lens group. Have to be. As a result, even if chromatic aberration can be corrected, it is 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 perform chromatic aberration correction in 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 a positive power as a whole is configured using only one positive lens and one negative lens, it is difficult to correct aberrations on the long focal length side, particularly spherical aberrations. become. Further, in order to correct higher-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 design freedom (number of lenses) for further aberration correction. It is preferred to give. Further, when the first lens group is configured using only one positive lens and one negative lens, it becomes difficult to perform chromatic aberration correction within the range of the optical constants of existing glass or plastic.

As described above, 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. In such a 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 performing chromatic aberration correction in the first lens group. 1 of the first lens group
By appropriately defining the Abbe numbers of the two negative lenses and the two positive lenses, chromatic aberration in the first lens group can be corrected well.

With respect to the conditional expression range (7), by further satisfying the following conditional expression range, better chromatic aberration correction becomes possible.

Ν n <32 (7a) ν n <30 (7b) In the zoom lens system of each embodiment, the first lens unit moves to the object side during zooming from the shortest focal length state to the longest focal length state. It has a configuration. This configuration,
The total length of the zoom lens system in the shortest focal length state can be made compact, and the lens diameter of the lens constituting the first lens group can be reduced, which is preferable. 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, it may satisfy the condition defined by the following conditional expression range (9). desirable. 0.7 <m1 / Z <3.0 (9) where, m1: the amount of movement (mm) of the first lens unit during zooming from the shortest focal length state to the longest focal length state, Z: zoom ratio (Z = ft / fw) : The focal length ratio between the shortest focal length state and the longest focal length state) The above condition represents the relationship between the amount of movement of the first lens unit during zooming from the shortest focal length state to the longest focal length state and the zoom ratio. I have. Generally, as the zoom ratio increases, the amount of movement increases. The condition defined by the conditional expression range (9) is a condition for providing a compact zoom lens having good optical performance by appropriately defining the amount of movement of the first lens group. Conditional expression range (9)
Exceeds the upper limit, the amount of movement of the first lens group is too large compared to the zoom ratio, and the total length in the longest focal length state is too large, so that a compact zoom lens cannot be obtained. Conversely, if the lower limit of the conditional expression range (9) is exceeded,
The moving amount of the first lens group is too small. If the amount of movement of the first lens group is 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, and the amount of aberration generated in the first lens group becomes large, so that good optical performance cannot be obtained as a whole.

Regarding the above condition, it is more preferable to satisfy the following conditional expression range (9a) of the conditional expression range (9). 0.8 <m1 / Z <3.0 (9a) As described above, when the first lens group moves to 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) where 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 When the focal length in the shortest focal length state is fw, and the focal length in the longest focal length state is ft, the intermediate focal length is (fw × ft) ^1/2 .

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

With respect to the above condition, the following conditional expression ranges (10a) to (1) of the conditional expression range (10) are set.
0b) is more preferably satisfied. 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 condition defined in 1). 1 <max (T1, T2, T3) / fw <4 (11) where Ti: the thickness on the optical axis of the i-th lens unit, and max (T1, T2, T3) is the maximum value.

The above conditions are for achieving a small and high-magnification zoom lens system. If the lower limit of the 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 reduced. Not only is it difficult to ensure, but it is not possible to ensure the degree of design freedom required for aberration correction. On the other hand, when the value exceeds the upper limit of the conditional expression range (11), the thickness on the optical axis of each lens unit becomes too large, so that a compact zoom lens system cannot be achieved.

Regarding the above condition, it is more preferable to satisfy the following conditional expression range (11a) of 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 condition defined 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 condition represents the telephoto ratio in the shortest focal length state. If the lower limit of conditional expression range (12) is exceeded,
The overall length of the optical system becomes too small, making it difficult to correct aberrations.
In addition, it is difficult to satisfy a substantially telecentric condition required for a photographing optical system for a digital camera. Conversely, if the upper limit of conditional expression range (12) is exceeded, compactness cannot be achieved. Furthermore, as the total length increases, the illuminance on the image plane cannot be ensured, so that the diameter of the front lens needs to be increased, so that a compact zoom lens system cannot be achieved.

In the zoom lens system, the focal length is changed by changing the interval between the groups, in other words, by changing the magnification (β) of each group. Therefore,
A lens group having a large change in zooming amount due to zooming contributes to zooming accordingly, and inevitably increases the aberration load. Considering this, when trying to zoom efficiently, It is desirable that each group of the zoom lens system bears the variable power as uniformly as possible. When such a relationship of the variable magnification load is realized, the aberration load of each lens group is equally distributed, and the configuration of the lens group of the zoom lens system has the same configuration (that is, the number of components and the size). ) 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) where 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 Ratio (lateral magnification in the longest focal length state / lateral magnification in the shortest focal length state).

The above condition is a condition indicating the variable magnification load of the second and third lens units. In the conventionally known zoom lens system, the zooming load of the second lens group is large, but the zooming load can be shared by the third lens group, so that zooming can be performed efficiently, and The system is shortened and the configuration of the lens group is reduced. Conditional expression range (1
If the lower limit of 3) is exceeded, the load of zooming on the third lens group is reduced and the load of zooming on the second lens group is increased. Thus, spherical aberration on the long focal length side tends to be under, and on the short focal length side. Also becomes large, making it impossible to correct aberration. Conversely, if the upper limit of conditional expression range (13) is exceeded, the third condition
Since the load of zooming on the lens group increases, spherical aberration on the long focal length side falls to the over side, and off-axis coma occurs on both the long and short focal length sides, and aberration correction by other components It becomes impossible to do. In either case, sufficient aberration correction cannot be performed with the configuration as it is, and an increase in the number of components and an increase in the size of the lens system in order to increase the degree of freedom in design cannot be avoided.

Regarding the above condition, the following conditional expression ranges (13a) to (1) of the conditional expression range (13) are set.
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) Also, the zoom lens system according to 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: lateral magnification of the second lens group in the longest focal length state, βw2: lateral magnification of the second lens group in the shortest focal length state.

The above condition is a condition for defining a change in the lateral magnification of the second lens unit at the time of zooming, and defines a variable magnification load of the second lens unit. When the value exceeds the upper limit of conditional expression range (14), the zooming load of the second lens group becomes too large, so that the spherical aberration on the long focal length side tends to be under, and the distortion on the short focal length side also decreases. And aberration correction becomes impossible. Conversely, when the value goes below the lower limit value of the conditional expression range (14), the load of zooming on the second lens unit decreases, and the load on the other lens units increases. In addition to falling down, off-axis coma 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 is the focal length in the longest focal length state, and f12w is the combined focal length of the first lens group and the second lens group in the 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 small 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 unit and the second lens unit on the short focal length side becomes too large, and it becomes difficult to secure the back focus. In addition, the power of the first lens group or the second lens group becomes too weak, and a compact zoom lens system cannot be achieved. Conversely, when the value exceeds the upper limit of the conditional expression range (15), the combined focal length of the first lens unit and the second lens unit on the short focal length side becomes too small, and it is difficult to correct distortion on the short focal length side. become. In addition, since the power of the first lens group or the second lens group becomes too strong, it becomes difficult to correct aberration, which is not desirable.

It is preferable that the zoom lens system according to each of the embodiments has at least one aspherical surface in the second lens group that satisfies the condition defined by the following conditional expression (16). -0.1 <φ × (N′-N) × d / dH {X (H) −X0 (H)} <0 (16) where φ: power of the aspherical surface, N: of the medium closer to the object side than the aspherical surface N ': Refractive index for the d-line of the medium on the image side of the aspherical surface, H: Height in the direction perpendicular to the optical axis, X (H): Optical axis 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.

Of the aspheric surfaces in the second lens group, the aspheric surface provided on the side relatively closer to the object side is effective for correcting distortion on the short focal length side and provided on the surface closer to the image side. The obtained aspherical surface is effective for correcting spherical aberration on the long focal length side. The function of the aspherical surface is to reduce the paraxial power, and the configuration of only the spherical surface serves to reduce the aberration that has been overcorrected. In the case of the embodiment, if the power of the aspheric surface of the negative surface provided on the lens close to the object side in the second lens group becomes too strong, the negative distortion on the short focal length side becomes too large, When the negative power becomes weaker, it is advantageous for correcting distortion on the short focal length side, but spherical aberration on the long focal length side is in an insufficiently corrected state, and optical performance cannot be ensured. The same applies to the case where the positive power surface in the second lens unit has an aspheric surface. The same phenomenon occurs when the power of the positive surface in the second lens unit is weak and when the negative power is strong. If the power of the aspheric 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 excess state. vice versa,
If the power becomes too strong, the correction will be insufficient, and neither is desirable.

It is preferable that the zoom lens system according to each of the embodiments has at least one aspherical surface satisfying the condition defined by the following conditional expression range (17) in the third lens unit. -0.1 <φ × (N'-N) × d / dH {X (H) -X0 (H)} <0 (17) where φ: power of the aspherical surface, N: of the medium closer to the object side than the aspherical surface N ': Refractive index for the d-line of the medium on the image side of the aspherical surface, H: Height in the direction perpendicular to the optical axis, X (H): Optical axis 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.

Of the aspherical surfaces in the third lens group, the aspherical surface relatively provided 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. As for the surface, it is effective for correcting the image surface property and the flare on the long focal length side. In the third lens group, if an aspheric surface is provided in a direction in which the positive power of the lens close to the object side is weakened, if the power becomes too weak, spherical aberration on the short focal length side will be insufficiently corrected, and conversely, If the power is too strong, the spherical aberration will be overcorrected. In either case, it becomes difficult to correct the aberration in the optical system after that, and as a result, an increase in the number of lenses or an increase in the size of the optical system is unavoidable for aberration correction. Also,
For the aspherical surface of the lens in the third lens group that is closer to the image plane and whose negative power is in the direction of weakening negative power, if the negative power is too weak, the convergence of off-axis rays on the long focal length side on the upper side will deteriorate, Excessive flare is generated, and as a result, image surface properties are deteriorated. On the short focal length side, the influence on off-axis rays becomes too strong, and excessive negative distortion occurs. Conversely, if the negative power is too strong, it will affect off-axis rays on the short focal length side, deteriorating the image surface properties on the short focal length side. Specifically, off-axis images on the short focal length side The surface falls in the positive direction, and the aberration cannot be corrected for other surfaces.

In each embodiment, it is desirable that the stop 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 the size of an optical apparatus incorporating the zoom lens system is increasing.

In each embodiment, the aperture is set to the second
It is desirable to arrange between the lens group and the third lens group. By arranging the stop between the second lens group and the third lens group, it is possible to prevent a decrease in the amount of peripheral light in a well-balanced manner when zooming from the shortest focal length state to the intermediate focal length state.

Furthermore, it is desirable that the diameter of the open stop be constant during zooming. Normally, the aperture is open FNO
The aperture is narrowed down by opening and closing the aperture blades with respect to the circular aperture corresponding to. Further, in consideration of the influence on the image, it is desirable that the aperture shape of the open stop is a circle. Therefore, in consideration of the effect on the image, if the diameter of the open aperture is different at each focal length state during zooming, the aperture is controlled by either performing this circular aperture with aperture blades or arranging a plurality of circular apertures. You need to control. However, in the case of using the former diaphragm blade, a small number of diaphragm blades requires a large number of blades, such as five or six blades, in order to obtain a distorted opening shape and to approach a circle, which inevitably increases the cost. Further, when a plurality of circular openings are provided as in the latter case, not only the cost is increased but also a space for inserting the circular openings in the optical axis direction is required, so that the size of the optical system is increased.

[0059]

EXAMPLES Examples of the present invention will be described below with reference to construction data, aberration diagrams and the like.

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

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 =
) Indicates the i-th axial top surface distance counted from the object side, and Ni (i = 1, 2, 3,...) And νi (i = 1, 2,
3) indicate the refractive index and Abbe number of the i-th lens counted from the object side with respect to the d-line. F represents the focal length of the entire system, and FNO represents the F number. In each embodiment, the focal length f of the entire system, the F-number FNO, and the air space between the lens units (the space between the upper surfaces of the axes) are, in order from the left, the shortest focal length end (wide-angle end) (W), The values correspond to the focal length (M) and the longest focal length end (telephoto end) (T).

Further, in each embodiment, the surface marked with * for the radius of curvature ri indicates that the surface is an aspheric refracting optical surface or a surface having a refracting action equivalent to the aspheric surface. Is defined by the following equation.

X (H) = CH ² / ｛1+ (1-εεC ² · H ² ) ^1/2 ｝ + ΣAi · Hi (AS) where H: height in the direction perpendicular to the optical axis X (H): Displacement in the optical axis direction at the position of height H (based on surface vertex), C: Paraxial curvature, ε: Quadratic surface parameter, Ai: i-th order aspherical coefficient, Hi: H A symbol representing 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] [axial top surface interval] [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 to 12.78 to 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 ~ 2.11 ~ 0.32 r14 = ∞ d14 = 3.00 ~ 2.00 ~ 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 ~ 7.89 ~ 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 = 1.34200 × 10 ^-5 A8 = 6.72379 × 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 [Radius of curvature] [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 ~ 13.58 ~ 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 ~ 0.11 r15 = ∞ d15 = 0.82 ~ 0.89 ~ 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 to 4.20 to 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 = -5.39814 × 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 ~ 15.50 ~ 48.75 Fno = 2.73 ~ 4.31 ~ 4.10 (curvature Radius] [axis top surface interval] [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 ~ 13.11 ~ 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 to 3.16 to 3.25 r23 = ∞ d23 = 3.70 N12 = 1.516800 ν12 = 64.20 r24 = ∞ [aspheric coefficient] r11 ε = 1.0000 A4 = -1.51649 × 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 × 10 ^-5 A10 = 9.96727 × 10 ^-6 A12 = -1.04625 × 10 ^-6 r22 ε = 1.0000 A4 = -3.78250 × 10 ^-3 A6 = -2.14667 × 10 ^-4 A8 = 6.93245 × 10 ^-5 A10 = -1.13196 × 10 ^-5 A12 = 7.18551 × 10 ^-7 << Example 4 >> f = 5.10-16.01-48.80 Fno = 3.10-3.60-4.20 [Radius of curvature] [Axis spacing] [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 = ∞ [ Aspheric 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 × 10 ^-5 A8 = -2.32713 × 10 ^-6 A10 = 7.09276 × 10 ^-8 r19 ε = 1.0000 A4 = -9.92974 × 10 ^-4 A6 = 1.23299 × 10 ^-5 A8 = 1.61718 × 10 ^-6 A10 = 3.97318 × 10 ⁻⁷ FIGS. 5 to 8 are aberration diagrams corresponding to Examples 1 to 4. Each aberration diagram represents a spherical aberration diagram, an astigmatism diagram, and a distortion aberration diagram in order from the left side. Each aberration diagram shows, in order from the top, aberrations of the optical system corresponding to the above-described shortest focal length state (wide-angle end), intermediate focal length state, and longest focal length state (telephoto end).

In each of the spherical aberration diagrams, the solid line d represents the amount of spherical aberration with respect to the d line, the dashed line g represents the amount of spherical aberration with respect to the g line (only in Example 3), and SC represents the amount of sine condition unsatisfaction. In each astigmatism diagram, a solid line DS represents a sagittal surface, and a dotted line DM represents a meridional surface. The vertical axis of the spherical aberration diagram represents the F-number of the light ray, 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 in each embodiment are shown below. In each data, the letter E after the number indicates an exponent part. For example, if 1.0E-2, 1.0 × 10 ^-2
Shall be expressed. 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.

Embodiment 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 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 92-0.7737E-036 1.6793-0.1280E-027 1.9589 -0.1917E-028 2.2388 -0.2672E-029 2.5186 -0.3528E-02 10 7985 -0.4352E-0
2 (17) φ × (N′−N) × d / dH {X (H) −X0 (H)} r22 No Height 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 N o 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 -0.7656 E-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- 0.2196E-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 0.7834E-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 / dH {X (H) -X0 (H)} r11 No Height 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 1 0.2609 -0.2158 E-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 / dH {X (H) -X0 (H)} r15 No Height 1 0.3069- 0.8057E-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 -0.6824 E-02 9 2.7623 -0.1156E-01 10 3.0692 -0.2027E-01 r21 No Height 1 0.2267 0.1954E-05 2 0.4534 0.1575E-04 3 0.6801 0.5 397E-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 -0.5091E-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 / dH {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 0.1038E-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 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 -0.1047E-02 8 2.2015 -0.1347E-02 9 2.4767 -0.1419E-02 10 2.7519 -0.8695E-03

[0068]

As described in detail above, according to the zoom lens system of the present invention, it is possible to provide a compact zoom lens system despite satisfying high image quality at a high magnification. is there.

Therefore, when the zoom lens system according to the present invention is applied to a photographing optical system of a digital camera, it is possible to contribute to high functionality and compactness of the camera.

[Brief description of the 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

Continued on the front page (72) Inventor Mamoru Terada 2-3-13 Azuchicho, Chuo-ku, Osaka City Inside Osaka International Building Minolta Co., Ltd. (72) Tetsuya Arimoto 2-3-1, Azuchicho, Chuo-ku, Osaka-shi Osaka International Building Minolta Co., Ltd. (72) Inventor Naoshi Okada 2-3-13 Azuchicho, Chuo-ku, Osaka City Osaka International Building Minolta Co., Ltd.

Claims (3)

[Claims] 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, wherein at least the first lens group has a positive power. A zoom lens system that performs zooming by moving a lens group, wherein the first lens group includes a negative lens, a positive lens, and a positive lens in order from the object side, and satisfies the following conditions. Zoom lens system; 0.7 <m1 / Z <3.0, where m1: the amount of movement (mm) of the first lens unit 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). 2. During zooming, the distance between the first lens group and the second lens group on the optical axis increases, and the distance between the second lens group and the third lens group on the optical axis decreases. The zoom lens system according to claim 1, wherein the first lens group and the third lens group move toward the object. 3. The zoom lens system according to claim 2, wherein said second lens group moves during zooming.