JP2000275520A - Zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zoom lens which has high performance and is small-sized and inexpensive by equipping a 1st lens group with a positive lens most on the object side and composing a 2nd lens group of three lenses. SOLUTION: The 1st lens group Gr1 having negative power is composed of a biconvex positive lens, a negative meniscus lens which is concave to the image side, a biconcave negative lens, and a positive meniscus lens which is convex to the object side in order from the object side. The 2nd lens group Gr2 having positive power is composed of a biconvex positive lens, a biconcave lens (whose surfaces are both aspherical), and a biconvex positive lens. Preferably, 0.1<|FF/F1|<0.6 holds. Here, FF is the focal length of the 1st lens group and F1 is the focal length of the positive lens most on the object side in the 1st lens group. Thus, the positive lens is arranged most on the object side of the 1st lens group Gr1 to excellently correct distortion, specially, the distortion on the short-focal-length side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens, and more particularly to a small and inexpensive zoom lens suitable for a digital still camera.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, digital still cameras that can easily capture images have become widespread. With the widespread use of such digital still cameras, cheaper digital still cameras have been demanded, and there has been a demand for further reduction in the cost of the photographing optical system. On the other hand, the number of pixels of a photoelectric conversion element tends to increase year by year, and a higher-performance imaging optical system is required. Therefore, it is necessary to meet conflicting demands for cost reduction and high performance. In response to the above demands, a compact CCD (Charge Coupled) as described in Japanese Patent Application Laid-Open No.
Many zoom lenses have been proposed for use in cameras having a device.

[0003]

However, in the zoom lens described in the above publication, an aspherical lens having a large diameter is used for the first lens group, resulting in an increase in cost. .

The present invention has been made in view of such circumstances, and has as its object to provide a high-performance, compact, and inexpensive zoom lens.

[0005]

To achieve the above object, a zoom lens according to a first aspect of the present invention comprises, in order from the object side, a first lens group having negative power and a second lens group having positive power. A zoom lens that performs zooming by changing the distance between the first lens group and the second lens group, wherein the first lens group has a positive lens closest to the object side, The second lens group includes three lenses.

A zoom lens according to a second aspect of the present invention is characterized in that, in the configuration of the first aspect, the following conditional expression (1) is further satisfied. 0.1 <| FF / F1 | <0.6 (1) where FF is the focal length of the first lens unit, and F1 is the focal length of the most object-side positive lens in the first lens unit.

A third aspect of the present invention is the zoom lens according to the first aspect, wherein the first lens group includes a positive lens, a negative lens, and a positive lens in order from the object side.

According to a fourth aspect of the present invention, in the zoom lens system according to the first aspect, the first lens group includes, in order from the object side, a positive lens, a negative lens, a negative lens, and a positive lens. I do.

In a fifth aspect of the present invention, in the zoom lens system according to the first aspect, the first lens group includes only spherical lenses.

According to a sixth aspect of the present invention, there is provided a zoom lens according to the first aspect, further satisfying the following conditional expression (2). 0.2 <| FW / FF | <0.8 (2) where FW is the focal length of the entire system at the wide-angle end, and FF is the focal length of the first lens group.

According to a seventh aspect of the present invention, in the zoom lens system according to the first aspect, the second lens group includes, in order from the object, a positive lens, a negative lens, and a positive lens.

An eighth aspect of the present invention is the zoom lens according to the seventh aspect, further satisfying the following conditional expression (3). 0.5 <| FR / FN | <1.5 (3) where, FR: focal length of the second lens group, FN: focal length of the negative lens in the second lens group.

A ninth aspect of the present invention is a zoom lens according to the first aspect, wherein the zoom lens is a two-unit zoom lens including only the first lens unit and the second lens unit.

A tenth aspect of the present invention is a zoom lens according to the first aspect.
In the configuration of the present invention, it is a three-unit zoom lens further provided with a third lens unit having a positive power on the image side of the second lens unit.

The zoom lens according to an eleventh aspect of the present invention is the zoom lens according to the first aspect.
0, wherein the following conditional expression (4) is further satisfied. 0.01 <FW / FC <0.61 (4) where FW is the focal length of the entire system at the wide-angle end, and FC is the focal length of the third lens group.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a zoom lens embodying the present invention will be described with reference to the drawings. 1 to 6 are lens configuration diagrams respectively corresponding to the zoom lenses of the first to sixth embodiments, and show the lens arrangement at the wide-angle end [W]. Arrows mj (j = 1, 2, 3) in each lens configuration diagram schematically show movement of the j-th lens unit (Gri) during zooming from the wide-angle end [W] to the telephoto end [T]. I have. Also, in each lens configuration diagram, the surface marked with ri (i = 1, 2, 3, ...) is the i-th surface counted from the object side, and the surface marked with * It is an aspheric surface. The axial top surface interval to which di (i = 1, 2, 3,...) is a variable interval that changes during zooming among the i-th axial top surface interval counted from the object side.

Each embodiment includes at least a first lens group (Gr1) having negative power and a second lens group (Gr2) having positive power in order from the object side. This is a zoom lens suitable for a digital still camera that performs zooming by changing the distance between the lens group (Gr1) and the second lens group (Gr2). Further, the first to fourth embodiments are two-group zoom lenses including only the first lens group (Gr1) and the second lens group (Gr2), and the fifth and sixth embodiments are This is a three-unit zoom lens further provided with a third lens unit (Gr3) having positive power on the image side of the two lens units (Gr2). In any of the embodiments, the second lens group (Gr2) is located between the first lens group (Gr1) and the second lens group (Gr2).
A diaphragm (SP) that zooms with (Gr2) is arranged, and a low-pass filter (LPF) is arranged closest to the image.

<< First Embodiment (FIG. 1, positive / negative / negative / positive / positive / negative / positive) >> In the first embodiment, each lens group is configured as follows from the object side. First lens group
(Gr1) includes a biconvex positive lens, a negative meniscus lens concave on the image side, a biconcave negative lens, and a positive meniscus lens convex on the object side. Second lens group (Gr2)
Is a biconvex positive lens and a biconcave negative lens (both surfaces are aspheric)
And a biconvex positive lens.

<< Second Embodiment (FIG. 2, positive / negative / positive / negative / positive / negative / positive) >> In the second embodiment, each lens unit is configured as follows in order from the object side. First lens group
(Gr1) includes a biconvex positive lens, a negative meniscus lens concave on the image side, a biconcave negative lens, and a positive meniscus lens convex on the object side. Second lens group (Gr2)
Is a biconvex positive lens and a negative meniscus lens concave on the image side.
(Both surfaces are aspheric) and a biconvex positive lens.

<< Third and Fourth Embodiments (FIGS. 3 and 4;
Positive-negative-positive-negative)) In the third and fourth embodiments,
Each lens group is configured as follows in order from the object side. The first lens group (Gr1) includes a positive meniscus lens convex on the image side, a biconcave negative lens, and a positive meniscus lens convex on the object side. The second lens group (Gr2)
A biconvex positive lens and a biconcave negative lens (both surfaces are aspheric),
And a biconvex positive lens.

<< Fifth Embodiment (FIG. 5, Positive / Negative Positive-Positive / Negative Positive-Positive) >> In the fifth embodiment, each lens unit is configured as follows in order from the object side. The first lens group (Gr1) includes a biconvex positive lens, a negative meniscus lens concave on the image side, a biconcave negative lens, and a positive meniscus lens convex on the object side. Second lens group (Gr
2) is composed of a biconvex positive lens, a negative meniscus lens concave on the image side (both surfaces are aspheric), and a biconvex positive lens. The third lens group (Gr3) includes a positive meniscus lens convex on the image side.

<< Sixth Embodiment (FIG. 6, Positive / Negative Positive / Positive / Negative Positive / Positive) >> In the sixth embodiment, each lens unit is configured as follows in order from the object side. The first lens group (Gr1) includes a positive meniscus lens convex on the image side, a biconcave negative lens, and a positive meniscus lens convex on the object side. The second lens group (Gr2) includes a biconvex positive lens, a negative meniscus lens concave on the image side (both surfaces are aspheric),
And a positive meniscus lens convex to the object side. The third lens group (Gr3) is composed of a biconvex positive lens.

As described above, any of the embodiments is the first embodiment.
The lens group (Gr1) has a positive lens closest to the object side,
The second lens group (Gr2) is composed of three lenses. As described above, the first lens group (Gr1) having negative power and the second lens group (Gr2) having positive power are located closest to the object side.
By disposing a positive lens closest to the object side of the first lens group (Gr1), it is possible to satisfactorily correct distortion, particularly on the short focal length side in a zoom lens having at least Become. In particular, by disposing a positive lens, it becomes possible to correct distortion on the short focal length side without disposing an aspheric surface closest to the object side of the first lens group (Gr1). The use of expensive aspheric lenses can be reduced without deteriorating the optical performance of the group (Gr1), which is extremely effective in reducing the cost of the optical system.

Further, the second lens group (Gr2) is set to 3
The second lens group (Gr2)
When the first lens unit (Gr1) is a zoom lens having a negative power, the load on the driving system of the second lens unit (Gr2), which has a large moving distance during zooming, can be reduced. Can be reduced, which is effective in reducing the cost of the optical unit. And the second
By configuring the lens group (Gr2) with three positive, negative, positive lenses, it is possible to reduce the change in astigmatism over the entire zoom range. In order to perform better aberration correction, it is desirable to provide an aspheric surface for the negative lens in the second lens group (Gr2).

Since the first lens unit (Gr1) is composed of three positive, negative, positive lenses in order from the object side, a great effect of correcting distortion and coma in a well-balanced manner can be obtained. Furthermore, the first lens group (Gr1) is composed of four positive, negative, negative and positive lenses in order from the object side, so that distortion and coma can be corrected even better than in the case of three positive and negative lenses. Can be balanced. However, of course, the four-element configuration increases the number of lenses,
Which of the three or four lens configuration to employ as the configuration of the first lens group (Gr1) may be appropriately selected in consideration of performance factors required for the optical system and factors such as cost and space.

By forming the first lens group (Gr1) with only spherical lenses, it is possible to greatly reduce costs as compared with an optical system using an aspherical lens. In particular, the first
In a zoom lens system in which the lens unit (Gr1) has a negative power, if a bright lens system is to be realized,
The effective diameter of the lens group (Gr1) tends to increase. When a lens having a large effective diameter is used as an aspheric lens, a great increase in cost cannot be avoided with a glass aspheric lens. Further, if the aspherical lens is a plastic lens, the focal length changes greatly with respect to the environmental temperature, and in recent years, there has been great dissatisfaction in terms of the reliability as an optical system of a digital still camera which is required to have high image quality. Therefore, the first
By configuring the lens group (Gr1) with only spherical lenses, it is not necessary to use expensive glass aspheric lenses, so that significant cost reduction is possible.

By using a negative / positive two-component zoom for the zoom lens, the structure of the lens barrel, particularly the moving structure of the zoom, becomes simple, leading to a reduction in the cost of the entire optical unit.
Further, by making the zoom lens a negative, positive, and positive three-component zoom, it becomes possible to secure telecentricity on the image side more than in the case of a negative and positive two-component zoom. This is advantageous for securing the illuminance of the peripheral portion when using the solid-state imaging device having a high pixel count.

<< Desirable Conditions >> Next, conditional expressions which the zoom lenses of the respective embodiments should satisfy will be described. It is not necessary that each embodiment satisfies all the conditional expressions described below at the same time. If each individual conditional expression is satisfied independently, it is possible to achieve a corresponding operation and effect. Of course, satisfying a plurality of conditional expressions will improve optical performance, miniaturization,
Needless to say, it is more desirable from the viewpoint of assembly and the like.

It is desirable to satisfy the following conditional expression (1). 0.1 <| FF / F1 | <0.6 (1) where FF is the focal length of the first lens group (Gr1), and F1 is the focal length of the most object-side positive lens in the first lens group (Gr1). .

Conditional expression (1) mainly defines a condition range for balancing distortion and coma. If the lower limit of conditional expression (1) is exceeded, negative distortion will increase.
On the other hand, when the value exceeds the upper limit of the conditional expression (1), coma aberration worsens and the adverse effect on astigmatism increases.

It is desirable to satisfy the following conditional expression (2). 0.2 <| FW / FF | <0.8 (2) where FW is the focal length of the entire system at the wide-angle end [W], and FF is the focal length of the first lens group (Gr1).

Conditional expression (2) defines a condition range for correcting aberration and appropriately maintaining the size of the optical system. Conditional expression
If the lower limit of (2) is exceeded, the power of the first lens unit (Gr1) becomes too weak, which is advantageous for aberration correction, but causes an increase in the overall length and an increase in the front lens diameter. Conversely, the conditional expression
If the value exceeds the upper limit of (2), the power of the first lens unit (Gr1) becomes too strong, which is advantageous for shortening the overall length. However, the image surface falls significantly toward the over side.

It is desirable to satisfy the following conditional expression (3). 0.5 <| FR / FN | <1.5 (3) where, FR: focal length of the second lens group (Gr2), FN: focal length of the negative lens in the second lens group (Gr2).

The conditional expression (3) mainly defines a condition range for balancing coma. If the lower limit of conditional expression (3) is exceeded, coma will deteriorate and the adverse effect on higher-order chromatic aberration of magnification will increase. On the other hand, when the value exceeds the upper limit of the conditional expression (3), coma aberration worsens, and the adverse effect on astigmatism increases.

It is desirable to satisfy the following conditional expression (4). 0.01 <FW / FC <0.61 (4) where FW is the focal length of the entire system at the wide-angle end [W], and FC is the focal length of the third lens group (Gr3).

Conditional expression (4) defines a condition range for correcting aberration and appropriately maintaining the size of the optical system. Conditional expression
If the lower limit of (4) is exceeded, the power of the third lens group (Gr3) becomes too weak, which is advantageous for aberration correction, but causes an increase in the overall length and an increase in the front lens diameter. Conversely, the conditional expression
If the value exceeds the upper limit of (4), the power of the third lens unit (Gr3) becomes too strong, which is advantageous for shortening the overall length. However, the image surface is significantly inclined to the over side.

It is desirable to satisfy the following conditional expression (5). -0.6 <(r1A + r1B) / (r1A-r1B) <2.0 (5) where, r1A: the radius of curvature of the object side surface of the positive lens closest to the object in the first lens group (Gr1), r1B: the first lens group ( Gr1) is the radius of curvature of the image side surface of the positive lens closest to the object side.

Conditional expression (5) mainly defines a condition range for balancing distortion and coma. If the lower limit of conditional expression (5) is exceeded, negative distortion will increase.
On the other hand, when the value exceeds the upper limit of the conditional expression (5), the coma aberration is deteriorated and the adverse effect on the astigmatism is increased.

It is desirable to satisfy the following conditional expression (6). 0.2 <| FF / FP | <1.0 (6) where FF is the focal length of the first lens unit (Gr1), and FP is the focal length of the positive lens closest to the image in the first lens unit (Gr1). .

Conditional expression (6) mainly defines a condition range for balancing coma. If the lower limit of conditional expression (6) is exceeded, coma will deteriorate and the adverse effect on higher-order chromatic aberration of magnification will increase. On the other hand, when the value exceeds the upper limit of the conditional expression (6), coma aberration worsens, and an adverse effect on astigmatism increases.

It is desirable to satisfy the following conditional expression (7). 0.5 <TR / FW <2.0 (7) where TR is the distance from the object side to the image side of the second lens group (Gr2), FW is the focal length of the entire system at the wide-angle end [W]. is there.

Conditional expression (7) defines a condition range for correcting aberration and appropriately maintaining the size of the optical system. Conditional expression
When the value exceeds the lower limit of (7), the power of the second lens unit (Gr2) becomes too strong, which is advantageous for shortening the overall length, but the image surface is significantly inclined to the over side. Conversely, when the value exceeds the upper limit of conditional expression (7), the power of the second lens unit (Gr2) becomes too weak, which is advantageous for aberration correction, but increases the total length.

It is desirable to satisfy the following conditional expression (8). 1 <img × R <20 (8) where img: maximum image height, R: effective diameter (diameter) of the surface closest to the image.

Conditional expression (8) mainly defines the size and aberration of the optical system and the condition range for appropriately maintaining the conditions specific to the video camera. 2. Description of the Related Art A solid-state imaging device (for example, a CCD) used for a video camera is generally provided with a microlens on the front surface of each light-receiving element for improving light-collecting properties. In order to sufficiently exhibit the characteristics of the microlens, it is necessary to make the light beam incident substantially parallel to the optical axis of the microlens (that is, substantially perpendicular to the light receiving surface of each light receiving element). For that purpose, the photographing optical system is required to be telecentric on the image side. If the upper limit of conditional expression (8) is exceeded, it will be more than necessary that the optical system be substantially telecentric, negative distortion will increase, and the image plane will fall significantly toward the under side. Conversely, if the lower limit of conditional expression (8) is exceeded, it will be difficult to satisfy substantially telecentricity, and even if satisfied, the back focus will be unnecessarily long, resulting in an increase in the size of the optical system itself. I will.

Each of the lens groups constituting the first to sixth embodiments is a refraction type lens that deflects an incident light beam by refraction (that is, deflection is performed at an interface between media having different refractive indexes). Lens), but is not limited to this. For example, a diffractive lens that deflects an incident light beam by diffraction, a hybrid refraction / diffraction lens that deflects an incident light beam by a combination of diffraction and refraction, and a refractive index distribution type that deflects an incident light beam according to a refractive index distribution in a medium. Each lens group may be constituted by a lens or the like.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a zoom lens embodying the present invention will be described more specifically with reference to construction data, aberration diagrams, and the like. In addition, the following Examples 1-6
Respectively correspond to the above-described first to sixth embodiments, and are lens configuration diagrams illustrating the first to sixth embodiments.
(FIGS. 1 to 6) show corresponding lens configurations of Examples 1 to 6, respectively.

In the construction data of each embodiment, ri (i = 1, 2, 3,...) Is the radius of curvature of the i-th surface counted from the object side, and di (i = 1, 2, 3,. ..) indicates the i-th axial top surface distance counted from the object side, and Ni (i = 1,2,3, ...), νi (i = 1,2,
3,...) Represent the refractive index (Nd) and Abbe number (νd) of the i-th optical element counted from the object side with respect to the d-line. In the construction data, the distance between the upper surfaces of the axes that changes during zooming is from the wide-angle end (short focal length end) [W] to the middle.
(Intermediate focal length state) Variable air interval from [M] to telephoto end (long focal length end) [T]. Each focal length state [W], [M], [T]
Are also shown together with the focal length f and the F-number FNO of the entire system.

A surface marked with an asterisk (*) is defined as a surface constituted by an aspheric surface, and is defined by the following equation (AS) representing the surface shape of the aspheric surface. The aspherical surface data of each aspherical surface is shown together with other data, and the values corresponding to the conditional expressions are shown in Table 1. X (H) = (C ・ H ² ) / {1 + √ (1-C ²・ H ² )} + (A4 ・ H ⁴ + A6 ・ H ⁶ + A8 ・ H ⁸ + A10 ・ H ¹⁰ + A12 ・H ¹² )… (AS) where X (H) is the displacement in the optical axis direction at the height H (based on the surface vertex), and H is the direction perpendicular to the optical axis. Height, C: paraxial curvature, Ai: i-th order aspheric coefficient.

7 to 12 are aberration diagrams respectively corresponding to the first to sixth embodiments. [W] is the wide-angle end, [M] is the middle, [T] is various aberrations at the telephoto end (from the left). In order, spherical aberration, astigmatism, and distortion are shown (Y ′: maximum image height). Further, in each aberration diagram, the solid line (d) represents the aberration for the d line, the dashed line (g) represents the aberration for the g line, the two-dot chain line (c) represents the aberration for the c line, and the dashed line (SC) represents the sine condition. The broken line (DM) indicates astigmatism with respect to the d-line on the meridional surface, and the solid line (DS) indicates astigmatism with respect to the d-line on the sagittal surface.

[0050]

[Aspherical surface data of twelfth surface (r12)] ε = 1.0000 A4 = −0.61201 × 10 ⁻³ A6 = 0.59746 × 10 ⁻⁵ A8 = −0.24463 × 10 ⁻⁶ A10 = −0.49318 × 10 ⁻⁹ A12 = -0.88892 × 10 ^-12

[Aspherical surface data of the thirteenth surface (r13)] ε = 1.0000 A4 = −0.48791 × 10 ⁻⁴ A6 = 0.16377 × 10 ⁻⁴ A8 = 0.10555 × 10 ⁻⁶ A10 = 0.39502 × 10 ⁻¹⁰ A12 = − 0.49995 × 10 ^-12

[0053]

[Aspherical surface data of twelfth surface (r12)] ε = 1.0000 A4 = −0.58746 × 10 ⁻³ A6 = 0.16863 × 10 ⁻⁵ A8 = −0.31408 × 10 ⁻⁶ A10 = 0.37284 × 10 ⁻⁷ A12 = -0.23694 × 10 ^-8

[Aspherical surface data of the thirteenth surface (r13)] ε = 1.0000 A4 = -0.10910 × 10 ^-3 A6 = 0.13363 × 10 ^-4 A8 = 0.42174 × 10 ^-7 A10 = -0.12506 × 10 ^-7 A12 = 0.16770 × 10 ^-8

<< Embodiment 3 >>

[Aspherical surface data of the tenth surface (r10)] ε = 1.0000 A4 = -0.71098 × 10 ^-3 A6 = 0.17639 × 10 ^-6 A8 = 0.84557 × 10 ^-6 A10 = -0.28993 × 10 ^-9 A12 = -0.79492 × 10 ^-8

[Aspherical surface data of eleventh surface (r11)] ε = 1.0000 A4 = −0.19528 × 10 ⁻³ A6 = 0.23130 × 10 ⁻⁴ A8 = −0.59546 × 10 ⁻⁷ A10 = −0.660618 × 10 ⁻⁸ A12 = -0.35085 × 10 ^-8

[0059]

[Aspherical surface data of the tenth surface (r10)] ε = 1.0000 A4 = −0.73963 × 10 ⁻³ A6 = −0.13926 × 10 ⁻⁵ A8 = 0.64428 × 10 ⁻⁶ A10 = −0.29946 × 10 ⁻⁷ A12 = -0.20662 × 10 ^-8

[Aspherical surface data of eleventh surface (r11)] ε = 1.0000 A4 = −0.18713 × 10 ⁻³ A6 = 0.20435 × 10 ⁻⁴ A8 = −0.29725 × 10 ⁻⁶ A10 = 0.47647 × 10 ⁻⁷ A12 = -0.36147 × 10 ^-8

Embodiment 5 f = 7.21 to 12.18 to 20.58, FNO = 3.30 to 4.20 to 5.77

[Aspherical surface data of twelfth surface (r12)] ε = 1.0000 A4 = -0.84595 × 10 ^-3 A6 = -0.93627 × 10 ^-5 A8 = 0.20290 × 10 ^-6 A10 = 0.95205 × 10 ^-7 A12 = -0.77924 × 10 ^-8

[Aspherical surface data of the thirteenth surface (r13)] ε = 1.0000 A4 = -0.14558 × 10 ^-3 A6 = 0.62395 × 10 ^-5 A8 = 0.21508 × 10 ^-5 A10 = 0.14191 × 10 ^-6 A12 =- 0.19090 × 10 ^-7

<< Embodiment 6 >> f = 8.24 to 13.02 to 20.58, FNO = 3.50 to 4.40 to 5.77

[Aspherical surface data of the tenth surface (r10)] ε = 1.0000 A4 = -0.74706 × 10 ^-3 A6 = -0.15529 × 10 ^-4 A8 = 0.29404 × 10 ^-6 A10 = 0.83231 × 10 ^-7 A12 = -0.76175 × 10 ^-8

[Aspherical surface data of eleventh surface (r11)] ε = 1.0000 A4 = −0.76105 × 10 ⁻⁴ A6 = −0.23448 × 10 ⁻⁵ A8 = 0.35961 × 10 ⁻⁵ A10 = 0.19380 × 10 ⁻⁷ A12 = -0.15717 × 10 ^-7

[0068]

[Table 1]

[0069]

As described above, according to the present invention, since the first and second lens groups of the zoom lens starting with negative / positive have an appropriate lens configuration, zooming is performed while maintaining high performance. The size and cost of the lens can be reduced. Further, when the present invention is applied to a zoom lens of a digital camera, it is possible to contribute to downsizing, cost reduction and high performance of the digital camera.

[Brief description of the drawings]

FIG. 1 is a lens configuration diagram of a first embodiment (Example 1).

FIG. 2 is a lens configuration diagram of a second embodiment (Example 2).

FIG. 3 is a lens configuration diagram of a third embodiment (Example 3).

FIG. 4 is a lens configuration diagram of a fourth embodiment (Example 4).

FIG. 5 is a lens configuration diagram of a fifth embodiment (Example 5).

FIG. 6 is a lens configuration diagram of a sixth embodiment (Example 6).

FIG. 7 is an aberration diagram of the first embodiment.

FIG. 8 is an aberration diagram of the second embodiment.

FIG. 9 is an aberration diagram of the third embodiment.

FIG. 10 is an aberration diagram of the fourth embodiment.

FIG. 11 is an aberration diagram of the fifth embodiment.

FIG. 12 is an aberration diagram of the sixth embodiment.

[Explanation of symbols]

 Gr1: First lens group SP: Aperture Gr2: Second lens group Gr3: Third lens group LPF: Low-pass filter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H087 KA03 NA02 PA06 PA07 PA08 PA17 PB06 PB07 PB08 QA02 QA03 QA07 QA12 QA14 QA22 QA25 QA26 QA32 QA34 QA41 QA42 QA45 QA46 RA05 RA12 RA13 RA21 RA36 RA43 SA46 SA07 SA07 SA74 SB04 SB05 SB14 SB22

Claims (11)

[Claims] A first lens group having a negative power and a second lens group having a positive power, in order from an object side, and a distance between the first lens group and the second lens group. Wherein the first lens group has a positive lens closest to the object side, and the second lens group has three lenses. 2. The zoom lens according to claim 1, further satisfying the following conditional expression (1): 0.1 <| FF / F1 | <0.6 (1) where FF is the first lens group. F1 is the focal length of the positive lens closest to the object side in the first lens group. 3. The first lens group includes, in order from an object side,
2. The zoom lens according to claim 1, comprising a positive lens, a negative lens, and a positive lens. 4. The method according to claim 1, wherein the first lens group is arranged in order from an object side.
2. The zoom lens according to claim 1, comprising a positive lens, a negative lens, a negative lens, and a positive lens. 5. The zoom lens according to claim 1, wherein said first lens group comprises only a spherical lens. 6. The zoom lens according to claim 1, wherein the following conditional expression (2) is further satisfied: 0.2 <| FW / FF | <0.8 (2) where FW: wide-angle end FF: focal length of the first lens group. 7. The second lens group is arranged in order from an object side.
2. The zoom lens according to claim 1, comprising a positive lens, a negative lens, and a positive lens. 8. The zoom lens according to claim 7, further satisfying the following conditional expression (3): 0.5 <| FR / FN | <1.5 (3) where FR is the second lens group. FN is the focal length of the negative lens in the second lens group. 9. The zoom lens according to claim 1, wherein the zoom lens is a two-unit zoom lens including only the first lens group and the second lens group. 10. The zoom lens according to claim 1, further comprising a third lens group having a third lens group having a positive power on the image side of said second lens group. 11. The zoom lens according to claim 10, further satisfying the following conditional expression (4): 0.01 <FW / FC <0.61 (4) where FW is the entire system at the wide-angle end. , FC: the focal length of the third lens group.