JP2012173657A - Zoom lens, information device, and portable information terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens having a substantially compact focus group, having a small moving amount of the focus group, being compact, having a high performance, a half-angle end of a wide field angle of 36.8° or more, a variable-power ratio of 3 times to 5 times, and a resolution adapted to an image pickup element with 5,000,000-10,000,000 pixels.SOLUTION: The zoom lens is disposed with in order from an object side to an image side along an optical axis: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a negative refractive power; and a subsequent group comprising a plurality of or a single lens group. The focusing is performed by the third lens group. A focal length of the second lens group, a focal length of the third lens group, a composite focal length of the second lens group and the third lens group at the telephoto end, and an intermediate focal length between a focal length of the entire system at the wide-angle end and a focal length of the entire system at the telephoto end satisfy predetermined conditional expressions.

Description

  The present invention relates to an improved zoom lens as a photographing optical system, an information device such as a digital camera, a silver salt camera, and a video camera using the zoom lens as a photographing optical system, and a portable information terminal device.

In recent years, zoom lenses have become common in photographic optical systems used in digital still cameras and the like. In particular, zoom lenses that include an angle of view of about 50 mm in a 35 mm size conversion in the focal length range are generally known. Furthermore, in these zoom lenses, there are demands from users for downsizing, widening of angles, and speeding up of autofocus (hereinafter referred to as “AF”).
As a configuration of the zoom lens, a so-called first lens group having a positive refractive power, a second lens group having a negative refractive power, and a succeeding subsequent group are arranged in order from the object side to the image side. Positive lead type zoom lenses are disclosed in Japanese Patent Application Laid-Open No. 3-228008, Japanese Patent Application Laid-Open No. 10-48518, Japanese Patent Application Laid-Open No. 11-44848, and Japanese Patent Application Laid-Open No. 11-44848. Japanese Patent Laid-Open No. 2000-28923) and Patent Document 5 (Japanese Patent Laid-Open No. 2010-175554). The reason for adopting such a configuration is, firstly, that it is easy to enlarge the zoom ratio, and secondly, that the total length can be reduced by the configuration in front of the positive group.

Conventionally, as a focusing method for these zoom lenses, a so-called inner focus method in which a second lens group is moved as shown in Patent Document 1 or the like is known. In this inner focus method, the weight of the group to be moved is large during focusing, so that the motor and the actuator become large, and the maximum diameter of the lens barrel increases. There was also a disadvantage that it would be disadvantageous in the calming of the inside.
As a method of reducing the weight of the focus group, a first lens group having a positive refractive power from the object side, a second lens group having a negative refractive power, a third lens group having a negative refractive power, and the subsequent Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5 show a method of performing focusing with a third lens group having a group. However, in the zoom lenses disclosed in Patent Document 2, Patent Document 3, and Patent Document 4, it is difficult to say that the focus group is light in weight, which is insufficient for the above-described user request.
In Patent Document 5, a method using one negative lens as a focus group is proposed. This method reduces the weight of the focus group, speeds up AF, reduces the lens barrel diameter, etc., but there is room for improvement in aberration correction because the focal length range of each lens group is not appropriate. The lens system is not sufficient in size.

  The present invention has been made in view of the above-described circumstances. The object of the present invention is to achieve a focus group that is sufficiently compact, has a small amount of focus group movement, is small and has high performance, and has a half angle of view at the wide angle end of 36. Providing a zoom lens capable of realizing a resolving power corresponding to an image pickup device exceeding 8 to 10 degrees, a zoom ratio of about 3 to 5 times, and exceeding 5 to 10 million pixels; An object is to provide an information device and a portable information terminal device to be used.

The zoom lens according to claims 1 to 7 of the present invention includes:
In order from the object side to the image side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a negative refractive power, And a succeeding group constituted by one lens group, and during zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the second lens group and the second lens group A zoom lens in which the distance between the third lens group is increased, the distance between the third lens group and the succeeding group is changed, and focusing is performed by the third lens group. It is what has.
That is, in order to achieve the above-mentioned object, the zoom lens according to claim 1
The focal length of the second lens group is F2, the focal length of the third lens group is F3, the combined focal length of the second lens group and the third lens group at the telephoto end is F23t, and the entire system at the wide angle end Where Fw is Fw, the focal length of the entire system at the telephoto end is Ft, and the intermediate focal length between the focal length Fw and the focal length Ft is Fm = √Fw × Ft, the following conditional expression (1): (2), (3):
(1) 2.0 <F3 / F23t <3.0
(2) -2.5 <F2 / Fm <-1.0
(3) -1.4 <F3 / Fm <-0.5
It is characterized by satisfying.

The zoom lens according to claim 2 is the zoom lens according to claim 1,
The third lens group is composed of one negative lens.
The zoom lens according to claim 3,
3. The zoom lens according to claim 1, wherein an Abbe number νd of the one negative lens in the third lens group is the following conditional expression (4):
(4) νd> 50
It is characterized by satisfying.
The zoom lens according to claim 4,
4. The zoom lens according to claim 1, wherein the succeeding group has an aperture stop, a fourth lens group having a positive refractive power, and a positive refractive power from the object side to the image side. The fifth lens group is arranged in this order.
The zoom lens according to claim 5,
5. The zoom lens according to claim 1, wherein all the lens groups are configured to move upon zooming.

The zoom lens according to claim 6,
6. The zoom lens according to claim 1, wherein the maximum image height is Y ′ and the focal length of the entire system at the wide-angle end is Fw, and the following conditional expression (5):
(5) 0.75 <Y ′ / Fw
It is characterized by satisfying.
The zoom lens according to claim 7,
7. The zoom lens according to claim 1, wherein the focal length of the entire system at the telephoto end is Ft, and the focal length of the entire system at the wide-angle end is Fw.
(6) 3.0 <Ft / Fw
It is characterized by satisfying.
An information device having a photographing function according to claim 8 is provided.
The zoom lens according to any one of claims 1 to 7 is provided as a photographing optical system.
An information device having a photographing function according to claim 9 is provided.
The information device according to claim 8, wherein an object image formed by a zoom lens is formed on a light receiving surface of an image sensor.
The portable information terminal device according to claim 10,
The zoom lens according to any one of claims 1 to 7 is provided as a photographing optical system of a photographing function unit.

  According to the present invention, the focus group is sufficiently compact, the amount of movement of the focus group is small, the amount of force required for movement is reduced, the size and performance are small, and the half angle of view at the wide-angle end is 36.8 degrees or more. A zoom lens having a resolving power corresponding to an image sensor having a magnification ratio of about 3 to 5 times and exceeding 5 to 10 million pixels can be provided, and the zoom lens as described above is used as a photographing optical system. By doing so, the focus group movement amount is small, the force required for the movement is reduced, and the speed of the automatic focusing operation is reduced, while achieving a wide angle of view and high zoom ratio. An information device and a portable information terminal device can be provided.

FIG. 2 is a cross-sectional view illustrating a configuration of an optical system of a zoom lens according to Embodiment 1 of the present invention and a zoom locus associated with zooming, in which (a) is a wide angle end, (b) is an intermediate focal length, and (c) is It is sectional drawing along the optical axis in each in a telephoto end. FIG. 6 is a diagram illustrating a configuration of an optical system of a zoom lens according to Example 2 of the present invention and a zoom locus associated with zooming, where (a) is a wide angle end, (b) is an intermediate focal length, and (c) is a telephoto end. It is sectional drawing along the optical axis in each. FIG. 6 is a diagram illustrating a configuration of an optical system of a zoom lens according to Example 3 of the present invention and a zoom locus associated with zooming, in which (a) is a wide angle end, (b) is an intermediate focal length, and (c) is a telephoto end. It is sectional drawing along the optical axis in each. FIG. 10 is a diagram illustrating the configuration of an optical system of a zoom lens according to Example 4 of the present invention and a zoom locus associated with zooming, where (a) is a wide angle end, (b) is an intermediate focal length, and (c) is a telephoto end. It is sectional drawing along the optical axis in each. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the wide angle end of the zoom lens according to Embodiment 1 of the present invention shown in FIG. 1. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the telephoto end of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the wide angle end of the zoom lens according to Embodiment 2 of the present invention shown in FIG. 2. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Example 2 of the present invention shown in FIG. 2. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the telephoto end of the zoom lens according to Example 2 of the present invention shown in FIG. 2. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the wide angle end of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the telephoto end of the zoom lens according to Embodiment 3 of the present invention shown in FIG. 3. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the wide angle end of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. FIG. 5 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the telephoto end of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 4. It is the perspective view seen from the to-be-photographed object side which shows typically the external appearance structure of the digital camera as an information apparatus which concerns on the 5th Embodiment of this invention. It is the perspective view seen from the photographer side which shows typically the external appearance structure of the digital camera of FIG. FIG. 18 is a block diagram schematically illustrating a functional configuration of the digital camera in FIG. 17.

Hereinafter, based on an embodiment of the present invention, a zoom lens, an information device, and a portable information terminal device according to the present invention will be described in detail with reference to the drawings.
Before describing specific examples, first, a fundamental embodiment of the present invention will be described. Here, FIGS. 1, 2, 3, and 4 are the first, second, third, and fourth embodiments. As will be described later, the first, second, and third embodiments will be described. Also, it will be used as Example 4.
The zoom lens according to the present invention includes, in order from the object side to the image side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a first lens group having a negative refractive power. A third lens group G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power, and are arranged between the third lens group G3 and the fourth lens group G4. With an aperture stop AD, the entire group moves during zooming from the wide-angle end to the telephoto end, and the first lens group G1, the fourth lens group G4, and the fifth lens group G5 move monotonously to the object side. Then, the second lens group G2 and the third lens group G3 move along a locus convex toward the image side or a part thereof, and the interval between the first lens group G1 and the second lens group G2 increases, and the second lens The distance between the group G2 and the third lens group G3 increases, and the distance between the third lens group G3 and the fourth lens group G4. Reduced, and the fourth lens group G4 decreases interval of the fifth lens group G5, the aperture stop AD moves integrally with the fourth lens group G4.

The first lens group G1 is, in order from the object side to the image side, a first lens L1 composed of a negative meniscus lens having a convex surface facing the object side, and a second lens composed of a positive meniscus lens having a convex surface facing the object side. The first lens L1 and the second lens L2 are composed of L2, and the two lenses, the first lens L1 and the second lens L2, are bonded closely together to form a cemented lens that is integrally joined.
The second lens group G2 includes a third lens L3 made of a negative meniscus lens having a convex surface facing the object side, and a fourth lens L4 made of a biconcave lens having a stronger concave surface on the image side and both surfaces being aspheric. The fifth lens L5 is a biconvex lens having a stronger convex surface on the image side.
The third lens group G3 includes a sixth lens L6 including a biconcave lens having a stronger concave surface directed toward the object side.
The fourth lens group G4 has a seventh lens L7 made of a biconvex lens having a stronger convex surface on the object side and both surfaces being aspherical surfaces, and an eighth lens L8 made of a biconvex lens having a stronger convex surface on the object side. The ninth lens L9 is composed of a biconcave lens having a stronger concave surface on the image side. The two lenses of the eighth lens L8 and the ninth lens L9 are closely bonded to each other and are integrally joined. A cemented lens is formed.

The fifth lens group G5 includes a tenth lens L10 made of a biconvex lens having a stronger convex surface on the image side and aspheric surfaces on both sides, and an eleventh lens L11 made of a negative meniscus lens having a convex surface directed to the image side. Become.
In the zoom lens configured as described above, the focal length of the second lens group is F2, the focal length of the third lens group is F3, the combined focal length of the second lens group and the third lens group at the telephoto end is F23t, and the wide-angle end. Let Fw be the focal length of the entire system at f, Ft be the focal length of the entire system at the telephoto end, and let the intermediate focal length Fm given by these focal lengths Fw and Ft be Fm = √ (Fw × Ft). The following conditional expressions (1), (2), (3):
(1) 2.0 <F3 / F23t <3.0
(2) -2.5 <F2 / Fm <-1.0
(3) -1.4 <F3 / Fm <-0.5
Is satisfied (corresponding to claim 1).
The conditional expressions (1), (2), and (3) are conditional expressions for balancing the focal length F2 of the second lens group and the focal length F3 of the third lens group, respectively. In the lens system of the present invention, the second lens group and the third lens group mainly perform a zooming function, and in order to reduce the size and improve the performance of the lens system, the second lens group and the focus lens group It is necessary to optimize the power arrangement of the third lens group that also functions as:

Conditional expression (1) is an expression indicating an appropriate balance range of the second lens group and the third lens group. If the upper limit of 3.0 is exceeded, the power of the third lens group decreases, the amount of movement during focusing increases, and the power of the second lens group increases, resulting in increased manufacturing error sensitivity. This is disadvantageous in terms of workability. If the lower limit value of 2.0 is not reached, the power of the third lens group becomes too large, the manufacturing error sensitivity is increased and the processability is disadvantageous, and the power of the second lens group is reduced. The balance with other lens groups that contribute to zooming is lost, making it difficult to correct various aberrations.
Conditional expression (2) and conditional expression (3) are expressions showing appropriate ranges to be taken by the second lens group and the third lens group, respectively. If the upper limit values of −1.0 and −0.5 are exceeded, the power of the respective lens groups becomes large. Therefore, the zooming range is narrow for the second lens group, and the focus of the third lens group is in focus. The moving distance is reduced, which is advantageous for downsizing, but the manufacturing error sensitivity is increased, which is disadvantageous in terms of workability. Also, if it is below the lower limit values of −2.5 and −1.4, the sensitivity of manufacturing error is reduced, which is advantageous in terms of workability, but not only the moving distance at the time of zooming and focusing is increased, Since the burden on the other lens groups becomes large, the balance is lost and it becomes difficult to correct various aberrations.

More preferably, it is desirable to satisfy the following conditional expressions (1 ′), (2 ′), and (3 ′).
(1 ') 2.2 <F3 / F23t <2.8
(2 ′) −2.4 <F2 / Fm <−1.2
(3 ′) −1.2 <F3 / Fm <−0.8
Furthermore, in order to reduce the weight of the focus group, it is desirable that the third lens group is a single negative lens. This makes it possible to increase the focus speed and reduce the noise (corresponding to claim 2).
In order to achieve higher performance, it is desirable that the Abbe number νd of the negative lens of the third lens group satisfies the following conditional expression (4) (corresponding to claim 3).
(4) νd> 50
The third lens group is composed of a single lens. By using a low dispersion glass here, the occurrence of various chromatic aberrations can be suppressed, the burden on the other groups is reduced, and this is advantageous for aberration correction.

More preferably, it is desirable that the Abbe number νd of the negative lens in the third lens group satisfies the following conditional expression (4 ′).
(4 ′) νd> 60
In order to further improve the performance, it is desirable that the subsequent group is an aperture stop, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power in order from the object side. Corresponding to).
By increasing the succeeding group, the burden on zooming of the front group is reduced and the degree of freedom is increased, which is advantageous in terms of aberration correction and workability, but it is a trade-off with downsizing of the optical system, It is appropriate to provide the fourth lens group and the fifth lens group having positive refractive power.
In order to achieve higher performance, it is desirable that all the lens groups move during zooming (corresponding to claim 5).
Since all the lens groups contribute to zooming, the burden on each group is reduced, which not only is advantageous in terms of aberration correction and workability, but also efficiently reduces the amount of movement of the first lens group. This is advantageous for downsizing.

In the zoom lens, it is desirable that the maximum image height Y ′ and the focal length Fw of the entire system at the wide-angle end satisfy the following conditional expression (5) (corresponding to claim 6).
(5) 0.75 <Y ′ / Fw
Conditional expression (5) regulates the angle of view, and a high-performance and compact zoom lens having a half angle of view of 36.8 degrees or more at the wide-angle end can be obtained.
In the zoom lens, it is desirable that the focal length Ft of the entire system at the telephoto end and the focal length Fw of the entire system at the wide-angle end satisfy the following conditional expression (6) (corresponding to claim 7).

(6) 3.0 <Ft / Fw
Here, conditional expression (6) regulates the zoom ratio, and a high-performance, wide-angle and compact zoom lens can be obtained with a zoom ratio of 3 or more.
More preferably, it is desirable to satisfy the following conditional expression (6 ′).
(6 ′) 3.0 <Ft / Fw <5
Although it may be simpler in terms of mechanism that the aperture diameter of the aperture is “constant regardless of zooming”, the change in the F number can be reduced by changing the aperture diameter at the telephoto end compared to the wide-angle end. You can also. When it is necessary to reduce the amount of light reaching the image plane, the diameter of the stop may be reduced. However, it is better to reduce the light amount by inserting a ND filter or the like without greatly changing the diameter of the stop. It is preferable because it can prevent a decrease.

The information device of the present invention is an information device having a photographing function characterized by having the zoom lens as a photographing optical system (corresponding to claim 8). In this information device, an object image by the zoom lens can be formed on the light receiving surface of the image sensor (corresponding to claim 9). As described above, the information device can be implemented as a digital camera, a video camera, a silver salt camera, or the like. However, the information device can be preferably applied as a portable information terminal device having the above-described zoom lens as a photographing optical system of a photographing function unit. Yes (corresponding to claim 10).
The zoom lens according to the present invention has a configuration in which the focus group is sufficiently compact, the focus group movement amount is small, the focus group movement force amount is small, a focusing operation can be performed at a high speed, and quietness can be achieved. A high-performance zoom lens with a half angle of view at the wide-angle end of 36.8 degrees or more, a zoom ratio of 3 to 5 times, sufficient aberration correction, and resolution that is compatible with high-resolution image sensors. By having the optical system, an information device and a portable information terminal device that are small and have high performance can be provided.
As the best mode for carrying out the present invention, four specific examples (numerical examples) of a zoom lens will be described below. As illustrated in FIG. 1 representing the first embodiment, in each embodiment, the parallel plate MF disposed on the image plane side of the fifth lens group G5 includes various filters such as an optical low-pass filter and an infrared cut filter, Assuming a cover glass (seal glass) of a light receiving element such as a CCD sensor, a transparent parallel plate equivalent to these is shown.

In the figure, MF represents an image plane.
The meanings of the symbols in the examples are as follows.
f: Focal length of the entire system F: F number (F value)
ω: Half angle of view R: Radius of curvature (Paraxial radius of curvature for aspheric surfaces)
D: Surface spacing nd: Refractive index νd: Abbe number K: Aspherical conical constant A4: Fourth-order aspherical constant A6: Sixth-order aspherical constant A8: Eighth-order aspherical constant A10: Tenth-order aspherical surface Constant A12: 12th-order aspherical constant A14: 14th-order aspherical constant The aspherical shape is such that the reciprocal of the paraxial radius of curvature (paraxial curvature) is c, the height from the optical axis is H, the conic constant is K, Using the aspheric coefficients of the above orders, and using X as the amount of aspheric surface in the optical axis direction, the well-known equation (7):

で表されるものであり、近軸曲率半径と円錐定数、非球面係数を与えて形状を特定する。

The shape is specified by giving a paraxial radius of curvature, a conic constant, and an aspherical coefficient.

  Although FIG. 1 has been described as the first embodiment, specifically, a cross-sectional view showing the lens configuration of the zoom lens according to Example 1 of the present invention and a specific intermediate focus from the wide angle end. FIG. 4 shows a zoom locus during zooming to the telephoto end via a distance, in which (a) is a cross-sectional view at the wide-angle end (wide), (b) is a cross-sectional view at a predetermined intermediate focal length (Mean), (C) is a cross-sectional view at the telephoto end (Tele). In FIG. 1 showing the position of the lens group in Example 1, the left side is the object side. In order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a negative refractive power, A fourth lens group G4 having a refractive power of 5 and a fifth lens group G5 having a positive refractive power are disposed, and an aperture stop AD is provided between the third lens group G3 and the fourth lens group G4. During zooming from the telephoto end to the telephoto end, the entire group moves, the first lens group G1, the fourth lens group G4, and the fifth lens group G5 move monotonously to the object side, and the second lens group G2 and the third lens The group G3 moves along a locus convex toward the image side or a part thereof, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 increases. The distance between the third lens group G3 and the fourth lens group G4 decreases, and the fourth lens group G4 and the fifth lens increase. Spacing G5 is reduced, the aperture stop AD moves integrally with the fourth lens group G4.

The first lens group G1 includes a first lens L1 composed of a negative meniscus lens having a convex surface facing the object side in order from the object side and a second lens L2 composed of a positive meniscus lens having a convex surface facing the object side. . The first lens L1 and the second lens L2 form a cemented lens that is integrally joined.
The second lens group G2 includes, in order from the object side, a third lens L3 composed of a negative meniscus lens having a convex surface directed toward the object side, and a fourth lens composed of a biconcave lens having a strong concave surface facing the image side and aspheric surfaces on both sides. A lens L4 and a fifth lens L5 made of a biconvex lens having a stronger convex surface on the image side are arranged.
The third lens group G3 includes a sixth lens L6 made of a biconcave lens having a stronger curved surface on the object side.
The fourth lens group G4 includes a seventh lens L7 composed of a biconvex lens having a stronger convex surface on the object side and both surfaces being aspherical surfaces, and an eighth lens L8 composed of a biconvex lens having a stronger convex surface directed to the object side. A ninth lens L9 made of a biconcave lens having a stronger concave surface on the image side is disposed. The two lenses of the eighth lens L8 and the ninth lens L9 are closely bonded to each other to form a cemented lens that is integrally joined.

The fifth lens group G5 has a tenth lens L10 composed of a biconvex lens having a stronger convex surface on the image side and aspheric surfaces on both sides, and an eleventh lens L11 composed of a negative meniscus lens having a convex surface directed to the image side. Is arranged.
The first lens group G1 to the fifth lens group G5 are supported by a common support frame or the like that is appropriate for each group, and operate simultaneously for each group during zooming or the like. It operates integrally with the lens group G4. 2 to 4 also show the surface numbers of the respective optical surfaces. 2 to 4 are also used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference symbol, and therefore common to the drawings according to other embodiments. Even though the reference numerals are attached, they are not necessarily in common with the other embodiments.
Specific numerical examples of the zoom lens of the present invention are shown below. In all the examples, the maximum image height is 14.3 mm. However, at the wide-angle end, the maximum image height is set to be as small as 12.3 mm in consideration of the amount of distortion aberration in order to apply distortion correction image processing in which the generated negative distortion aberration is generated by enlarging the image. It is.
That is, in the zoom lenses of Examples 1 to 4, as described above, aberration correction is performed by image processing for distortion. That is, in the zoom lenses of Examples 1 to 4, barrel distortion occurs in the imaging range at the wide angle end.

On the other hand, the occurrence of distortion is suppressed at the intermediate focal length, in the vicinity thereof, and at the telephoto end. In order to electrically correct the distortion, the effective imaging range is a barrel shape at the wide-angle end and a rectangular shape at the intermediate focal length and the telephoto end. Then, the effective imaging range at the wide-angle end is image-converted by image processing, and converted into rectangular image information with reduced distortion so that the corrected image height is 14.3 mm. Therefore, in Examples 1 to 4, the paraxial image height at the wide-angle end is set to 12.3 mm, which is smaller than the image height at the intermediate focal length and the image height at the telephoto end. As a result, the aberrations of the respective examples are sufficiently corrected, and it is possible to realize the resolving power corresponding to the light receiving elements exceeding 5 to 10 million pixels. It is clear from Examples 1 to 4 that by configuring the zoom lens as in the present invention, very good image performance can be ensured while achieving sufficient size reduction.
The optical characteristics of each optical element in Example 1 are as shown in Table 1 below.
In the examples, “HOYA” is the name of the optical glass manufactured by HOYA, and “OHARA” is the name of the optical glass manufactured by OHARA.

  In the first embodiment, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 16.15 to 53.85, F = 3.65 to 5.87, ω, respectively, by zooming. = 41.5 to 14.87.

In Table 1, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspherical surface, that is, in Table 1, the sixth surface and the seventh surface with “*” attached. The optical surfaces of the surface, the thirteenth surface, the fourteenth surface, the eighteenth surface, and the nineteenth surface are aspherical surfaces, and the parameters of each aspherical surface in the equation (7) are as follows.
Aspheric surface 6th surface K = 0
A4 = −4.574070E−05
A6 = 2.025770E-07
A8 = 4.226600E-09
A10 = −1.133690E-10
A12 = 1.002020E-12

The seventh side K = 0
A4 = −6.053710E−05
A6 = 4.194320E-07
A8 = −5.2241680E-09
A10 = 4.4414260E-11
13th surface K = 0
A4 = −3.776730E−05
A6 = −1.265330E-06
A8 = 2.299780E-08
A10 = -5.701440E-10

14th surface K = 0
A4 = 2.657950E-05
A6 = −1.333820E-06
A8 = 2.149520E-08
A10 = −5.004250E−10
18th surface K = 1.150062
A4 = 1.119530E-05
A6 = -7.160660E-07
A8 = 1.145640E-08
A10 = 1.598030E-10
19th surface K = −2.234150E-01
A4 = 9.627960E-05
A6 = 8.889440E-08
A8 = −1.3445540E−09
A10 = 1.925800E-10
A12 = 1.432410E-12
Here, En represents a power of 10.

  The variable distance DA between the first lens group G1 and the second lens group G2, the variable distance DB between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the aperture stop AD. The variable interval DC and the variable interval DD between the fourth lens group G4 and the fifth lens group G5 are changed as shown in the following table with zooming.

In addition, FIGS. 5, 6, and 7 sequentially show spherical aberration, astigmatism, distortion aberration, and coma aberration diagrams at the wide angle end, the intermediate focal length, and the telephoto end of the first embodiment. The broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional. Further, “g” and “d” represent the g line and the d line, respectively. The same applies to the aberration diagrams of the other examples.
Each value in conditional expression (1) to conditional expression (6) in the first embodiment is as shown in Table 3 below.

  In the zoom lens of Example 1 described above, the values of the parameters related to the conditional expressions (1) to (6) described above are all within the range of the conditional expressions.

  FIG. 2 shows the second embodiment and, more specifically, is a cross-sectional view showing a lens configuration of a zoom lens according to Example 2 of the present invention, and is a specific intermediate from the wide-angle end. 2A and 2B show zoom trajectories when zooming to a telephoto end through a focal length, in which (a) is a cross-sectional view at the wide-angle end (wide), and (b) is a cross-sectional view at a predetermined intermediate focal length (Mean). (C) is a sectional view at the telephoto end (Tele). In FIG. 2 showing the lens group position of Example 2, the left side in the drawing is the object side. 2, in order from the object side to the image side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a negative refractive power. A third lens group G3 having a positive refractive power, a fifth lens group G5 having a positive refractive power, and a third lens group G3 between the third lens group G3 and the fourth lens group G4. And an aperture stop AD at the time of zooming from the wide-angle end to the telephoto end, the entire group moves, and the first lens group G1, the fourth lens group G4, and the fifth lens group G5 move monotonously to the object side. The second lens group G2 and the third lens group G3 move along a locus convex toward the image side or a part thereof, and the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group The distance between G2 and the third lens group G3 increases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. A fourth lens group G4 decreases interval of the fifth lens group G5, the aperture stop AD moves integrally with the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a first lens L1 composed of a negative meniscus lens having a convex surface facing the object side and a second lens L2 composed of a positive meniscus lens having a convex surface facing the object side. Yes. The first lens L1 and the second lens L2 are closely bonded to each other to form a cemented lens that is integrally joined.
The second lens group G2 includes, in order from the object side, a third lens L3 composed of a negative meniscus lens having a convex surface directed toward the object side, and a fourth lens composed of a biconcave lens having a strong concave surface facing the object side and aspheric surfaces on both sides. A lens L4 and a fifth lens L5 made of a biconvex lens formed on both sides with the same radius of curvature are disposed.
The third lens group G3 includes a sixth lens L6 made of a biconcave lens having a stronger concave surface on the object side.
The fourth lens group G4 includes a seventh lens L7 composed of a biconvex lens having a stronger convex surface on the object side and both surfaces being aspherical surfaces, and an eighth lens L8 composed of a biconvex lens having a stronger convex surface directed to the object side. A ninth lens L9 made of a biconcave lens having a stronger concave surface on the image side is disposed. The two lenses of the eighth lens L8 and the ninth lens L9 are closely bonded to each other to form a cemented lens that is integrally joined.

The fifth lens group G5 has a tenth lens L10 composed of a biconvex lens having a stronger convex surface on the image side and aspheric surfaces on both sides, and an eleventh lens L11 composed of a negative meniscus lens having a convex surface directed to the image side. Is arranged.
Regarding the lens configuration of Example 2, the fourth lens L4 of the second lens group G2 is a biconcave lens having a strong concave surface facing the object side and an image-side surface being aspheric, and the fifth lens L5 is double-sided. Both are different from the first embodiment in that they are biconvex lenses having a convex surface having the same radius of curvature.
Specific numerical example 2 of the zoom lens according to the present invention will be described below. In Example 2, the maximum image height is 14.3 mm. However, at the wide-angle end, the maximum image height is set to be as small as 12.3 mm in consideration of the amount of distortion aberration in order to apply distortion correction image processing in which the generated negative distortion aberration is generated by enlarging the image. It is.
As a result, the aberration of Example 2 is sufficiently corrected, and it is possible to realize a resolving power corresponding to a light receiving element exceeding 5 million to 10 million pixels. It is clear from Example 2 that a very good image performance can be ensured while achieving a sufficiently small size by configuring the zoom lens as in the present invention.
The optical characteristics of the optical elements in Example 2 are as shown in Table 4 below.
In addition, in the glass material name in each Example, “HOYA” is an optical glass type name manufactured by HOYA Corporation, and “OHARA” is an optical glass type name manufactured by OHARA Corporation.
In Example 2, the focal length f, the F number F, and the half angle of view ω of the entire optical system are f = 16.15 to 53.9, F = 3.68 to 5.85, ω by zooming, respectively. = 41.5 to 14.87.

In Table 4, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspherical surface.
That is, in Table 4, the optical surfaces of the sixth surface, the seventh surface, the thirteenth surface, the fourteenth surface, the eighteenth surface, and the nineteenth surface marked with “*” are aspheric surfaces, and the expression (7 The parameters of each aspheric surface in) are as follows.
Aspheric surface 6th surface K = 0
A4 = 3.123280E-05
A6 = −1.689150E−06
A8 = 2.900870E-08
A10 = −1.762800E−10
A12 = −2.332320E-13
The seventh side K = 0
A4 = −7.601240E-06
A6 = −1.543080E-06
A8 = 2.333940E-08
A10 = -1.740290E-10

13th surface K = 0
A4 = −6.154640E-05
A6 = −9.647410E-07
A8 = 9.554530E-09
A10 = -1.932580E-10
14th surface K = 0
A4 = 3.097760E-05
A6 = −1.074140E-06
A8 = 1.148390E-08
A10 = -1.725320E-10
18th surface K = 1.48371E + 00
A4 = −7.552000E-06
A6 = 3.933000E-07
A8 = -2.707560E-08
A10 = 5.5470440E-10

19th surface K = −2.013300E-01
A4 = 5.438610E-05
A6 = 2.628790E-07
A8 = 7.452260E-09
A10 = −3.8862870E−10
A12 = 8.237870E-12
The variable distance DA between the first lens group G1 and the second lens group G2, the variable distance DB between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the aperture stop AD. The variable interval DC and the variable interval DD between the fourth lens group G4 and the fifth lens group G5 are changed as shown in Table 5 along with zooming.

In addition, FIGS. 8, 9, and 10 sequentially show spherical aberration, astigmatism, distortion aberration, and coma aberration diagrams at the wide-angle end, the intermediate focal length, and the telephoto end of the second embodiment. The broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional. Further, “g” and “d” represent the g line and the d line, respectively.
Each value in conditional expression (1) to conditional expression (6) in Example 2 described above is as shown in Table 6 below.

  In the zoom lens of Example 2 described above, the values of the parameters related to the conditional expressions (1) to (6) described above are all within the range of the conditional expressions.

  FIG. 3 shows a third embodiment. Specifically, FIG. 3 is a cross-sectional view showing a lens configuration of a zoom lens according to Example 3 of the present invention, and a specific intermediate focal length from the wide angle end. 3A and 3B show zoom trajectories during zooming to the telephoto end, wherein (a) is a cross-sectional view at the wide-angle end (wide), (b) is a cross-sectional view at a predetermined intermediate focal length (Mean), and (C) is a sectional view at the telephoto end (Tele). In FIG. 3 showing the lens group position of Example 3, the left side is the object side. A first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens having a negative refractive power in order from the object side to the image side along the optical axis. A lens group G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a positive refractive power are arranged, and an aperture stop AD is provided between the third lens group G3 and the fourth lens group G4. And at the time of zooming from the wide-angle end to the telephoto end, the entire group moves, the first lens group G1, the fourth lens group G4, and the fifth lens group G5 move monotonously to the object side, and the second lens The group G2 and the third lens group G3 move along a locus convex toward the image side or a part thereof, the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third lens group G3 move. The distance between the lens group G3 increases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the fourth lens group. 4 the distance of the fifth lens group G5 decreases, the aperture stop AD, moves integrally with the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a first lens L1 composed of a negative meniscus lens having a convex surface facing the object side and a second lens L2 composed of a positive meniscus lens having a convex surface facing the object side. Yes. The first lens L1 and the second lens L2 are closely bonded to each other to form a cemented lens that is integrally joined.
The second lens group G2 includes, in order from the object side, a third lens L3 composed of a negative meniscus lens having a convex surface directed toward the object side, and a fourth lens composed of a biconcave lens having a strong concave surface facing the image side and aspheric surfaces on both sides. A lens L4 and a fifth lens L5 made of a biconvex lens with both surfaces having convex surfaces having the same radius of curvature are disposed.
The third lens group G3 includes a sixth lens L6 made of a negative meniscus lens having a convex surface facing the image side.
The fourth lens group G4 includes a seventh lens L7 composed of a biconvex lens having a stronger convex surface on the object side and both surfaces being aspherical surfaces, and an eighth lens L8 composed of a biconvex lens having a stronger convex surface directed to the object side. A ninth lens L9 made of a biconcave lens having a stronger concave surface on the image side is disposed. The two lenses of the eighth lens L8 and the ninth lens L9 are closely bonded to each other to form a cemented lens that is integrally joined.

The fifth lens group G5 has a tenth lens L10 composed of a biconvex lens having a stronger convex surface on the image side and aspheric surfaces on both sides, and an eleventh lens L11 composed of a negative meniscus lens having a convex surface directed to the image side. Is arranged.
Specific numerical examples of the zoom lens according to the present invention will be shown below. In Example 3, the maximum image height is 14.3 mm. However, at the wide-angle end, the maximum image height is set to be as small as 12.3 mm in consideration of the amount of distortion aberration in order to apply distortion correction image processing in which the generated negative distortion aberration is generated by enlarging the image. It is.
As a result, as shown in the respective aberration curve diagrams shown in FIGS. 11 to 13, the aberrations of the respective examples are sufficiently corrected, and a resolving power corresponding to a light receiving element exceeding 5 to 10 million pixels is realized. It is possible to do. It is clear from Example 3 that by configuring the zoom lens as in the present invention, very good image performance can be ensured while achieving sufficient size reduction.
The optical characteristics of the optical elements in Example 3 are as shown in Table 7 below.
In the examples, “HOYA” is the name of optical glass manufactured by HOYA Corporation, and “OHARA” is the name of optical glass manufactured by OHARA INC.
In Example 3, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 16.15 to 53.85, F = 3.69 to 5.60, ω, respectively, by zooming. = 41.5 to 14.9.

In Table 7, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspherical surface.
That is, in Table 7, the optical surfaces of the sixth surface, the seventh surface, the thirteenth surface, the fourteenth surface, the eighteenth surface, and the nineteenth surface marked with “*” are aspherical surfaces. The parameters of each aspheric surface in) are as follows.
Aspherical surface 6th surface K = 0.0
A4 = -3.432080E-05
A6 = −1.317580E-07
A8 = 1.551760E-09
A10 = -3.7778470E-11 A12 = 9.109900E-13
7th surface K = 0.0
A4 = −5.719400E−05
A6 = −3.697210E−08
A8 = −5.3321940E-09
A10 = 8.765160E-11 13th surface K = 0.0
A4 = −1.261050E−05
A6 = −5.8882750E-07
A8 = 1.310640E-08
A10 = −3.2236260E−10

14th surface K = 0.0
A4 = 3.021540E-05
A6 = −6.4444950E-07
A8 = 1.762480E-08
A10 = -3.948560E-10
18th surface K = 1.392250E-01
A4 = 2.530150E-06
A6 = 5.784150E-08
A8 = -2.182630E-09
A10 = 1.154860E-10 19th surface K = -9.257800 E-02
A4 = 7.928330E-05
A6 = 4.663410E-07
A8 = -1.003880E-08 A10 = 1.913560E-10
The variable distance DA between the first lens group G1 and the second lens group G2, the variable distance DB between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the aperture stop AD. The variable interval DC and the variable interval DD between the fourth lens group G4 and the fifth lens group G5 are changed as shown in the following table with zooming.

In addition, FIGS. 11, 12, and 13 sequentially show aberration diagrams of spherical aberration, astigmatism, distortion, and coma aberration at the wide-angle end, the intermediate focal length, and the telephoto end of Example 3. The broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional. “G” and “d” represent the g-line and the d-line, respectively.
Each value in conditional expression (1) to conditional expression (6) in Example 3 described above is as shown in Table 9 below.

  In the zoom lens of Example 3 described above, the values of the parameters related to the conditional expressions (1) to (6) described above are all within the range of the conditional expressions.

  FIG. 4 shows a zoom lens according to the fourth embodiment. Specifically, FIG. 4 is a cross-sectional view showing the lens configuration of the zoom lens according to Example 4 of the present invention, and a specific view from the wide-angle end. 2A and 2B show zoom trajectories during zooming to the telephoto end through the intermediate focal length of FIG. 1, in which (a) is a cross-sectional view at the wide-angle end (wide), and (b) is at a predetermined intermediate focal length (Mean). Sectional drawing and (c) are sectional views at the telephoto end (Tele). In FIG. 4 showing the position of the lens group in Example 4, the left side is the object side. 4, in order from the object side to the image side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a negative refractive power. A third lens group G3 having a positive refractive power, a fifth lens group G5 having a positive refractive power, and a third lens group G3 between the third lens group G3 and the fourth lens group G4. And an aperture stop AD at the time of zooming from the wide-angle end to the telephoto end, the entire group moves, and the first lens group G1, the fourth lens group G4, and the fifth lens group G5 move monotonously to the object side. The second lens group G2 and the third lens group G3 move along an image side convex locus or a part thereof, and the distance between the first lens group G1 and the second lens group G2 increases, and the second lens group The distance between G2 and the third lens group G3 increases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. A fourth lens group G4 decreases interval of the fifth lens group G5, the aperture stop AD moves integrally with the fourth lens group G4.

The first lens group G1 includes, in order from the object side, a first lens L1 composed of a negative meniscus lens having a convex surface facing the object side and a second lens L2 composed of a positive meniscus lens having a convex surface facing the object side. Yes. The first lens L1 and the second lens L2 are closely bonded to each other to form a cemented lens that is integrally joined.
The second lens group G2 includes, in order from the object side, a third lens L3 composed of a negative meniscus lens having a convex surface directed toward the object side, and a fourth lens composed of a biconcave lens having a strong concave surface facing the image side and aspheric surfaces on both sides. A lens L4 and a fifth lens L5 made of a biconvex lens having both surfaces formed on curved surfaces having the same radius of curvature are disposed.
The third lens group G3 includes a sixth lens L6 made of a negative meniscus lens having a convex surface facing the image surface side.
The fourth lens group G4 includes a seventh lens L7 composed of a biconvex lens having a stronger convex surface on the object side and both surfaces being aspherical surfaces, and an eighth lens L8 composed of a biconvex lens having a stronger convex surface directed to the object side. A ninth lens L9 made of a biconcave lens having a stronger concave surface on the image side is disposed. The two lenses of the eighth lens L8 and the ninth lens L9 are closely bonded to each other to form a cemented lens that is integrally joined.

The fifth lens group G5 has a tenth lens L10 composed of a biconvex lens having a stronger convex surface on the image side and aspheric surfaces on both sides, and an eleventh lens L11 composed of a negative meniscus lens having a convex surface directed to the image side. Is arranged.
Specific numerical example 4 of the zoom lens according to the present invention will be described below. In Example 2, the maximum image height is 14.3 mm.
As a result, the aberration of Example 4 is sufficiently corrected, and it is possible to realize a resolving power corresponding to a light receiving element exceeding 5 million to 10 million pixels. It is clear from Example 4 that by configuring the zoom lens as in the present invention, a very good image performance can be secured while achieving a sufficiently small size.
The optical characteristics of the optical elements in Example 4 are as shown in Table 10 below.
In the glass material names in Example 4, “HOYA” is an optical glass type name manufactured by HOYA Co., Ltd., and “OHARA” is an optical glass type name manufactured by OHARA Co., Ltd. .
In Example 4, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 16.15 to 53.85, F = 3.68 to 5.55, ω, respectively, by zooming. = 41.5 to 14.87.

In Table 10, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspherical surface.
That is, in Table 10, the optical surfaces of the sixth surface, the seventh surface, the thirteenth surface, the fourteenth surface, the eighteenth surface, and the nineteenth surface marked with “*” are aspheric surfaces, and the expression (7 The parameters of each aspheric surface in) are as follows.
Aspheric surface 6th surface K = 0
A4 = −3.843970E−05
A6 = 1.21950E-07
A8 = −5.4666700E-09
A10 = 3.589930E-11
A12 = 5.576910E-13
The seventh side K = 0
A4 = −6.222930E−05
A6 = 1.289240E-07
A8 = −9.269550E−09
A10 = 1.049680E-10

13th surface K = 0
A4 = 4.838910E-06
A6 = −2.840070E-07
A8 = 8.697220E-09
A10 = −1.836370E-11
14th surface K = 0
A4 = 4.669360E-05
A6 = −1.627670E-07
A8 = 5.742440E-09
A10 = 2.564070E-11
18th side K = -1.373112E + 00
A4 = 1.668360E-05
A6 = 1.266830E-07
A8 = -5.146740E-09
A10 = 1.518190E-10
19th surface K = −2.895300E-02
A4 = 7.250660E-05
A6 = 6.9967700E-07
A8 = −1.676340E−08
A10 = 2.591100E-10
The variable distance DA between the first lens group G1 and the second lens group G2, the variable distance DB between the second lens group G2 and the third lens group G3, and the distance between the third lens group G3 and the aperture stop AD. The variable interval DC and the variable interval DD between the fourth lens group G4 and the fifth lens group G5 are changed as shown in the following table with zooming.

Further, FIGS. 14, 15 and 16 sequentially show aberration diagrams of spherical aberration, astigmatism, distortion and coma aberration at the wide-angle end, the intermediate focal length, and the telephoto end of Example 4. The broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional. Further, “g” and “d” represent the g line and the d line, respectively.
Each value in conditional expression (1) to conditional expression (6) in Example 4 described above is as shown in Table 12 below.

In the zoom lens of Example 4 described above, the values of the parameters related to the conditional expressions (1) to (6) described above are all within the range of the conditional expressions.
Next, a digital camera as an imaging apparatus according to the second embodiment of the present invention configured by adopting the above-described zoom lens according to the first embodiment of the present invention as an imaging optical system will be described with reference to FIGS. This will be described with reference to FIG. FIG. 17 is a perspective view schematically showing the external appearance of the digital camera viewed from the front side that is the object side, that is, the subject side, and FIG. 18 is a schematic external view of the digital camera viewed from the back side that is the photographer side. FIG. 19 is a schematic block diagram showing a functional configuration of a digital camera. Here, the image pickup apparatus is described taking a digital camera as an example, but the zoom lens according to the present invention may be employed in a silver salt film camera using a silver salt film as a conventional image recording medium. In addition, an information device such as a so-called PDA (personal data assistant) or a portable information terminal device such as a cellular phone in which a camera function is incorporated is widely used. Although such an information device also has a slightly different appearance, it includes substantially the same functions and configuration as a digital camera, and the zoom lens according to the present invention is adopted as an imaging optical system in such an information device. May be.

As shown in FIGS. 17 and 18, the digital camera includes a photographing lens 101, an optical viewfinder 102, a strobe (flashlight) 103, a shutter button 104, a camera body 105, a power switch 106, a liquid crystal monitor 107, an operation button 108, and a memory. A card slot 109 and a zoom switch 110 are provided. Further, as shown in FIG. 19, the digital camera includes a central processing unit (CPU) 111, an image processing device 112, a light receiving element 113, a signal processing device 114, a semiconductor memory 115 and a communication card 116.
The digital camera includes a photographing lens 101 as an imaging optical system and a light receiving element 113 configured as an image sensor using a CMOS (complementary metal oxide semiconductor) imaging element or a CCD (charge coupled device) imaging element. The light receiving element 113 reads an optical image of a subject (object) formed by the photographing lens 101. As the photographing lens 101, the zoom lens according to the present invention as described in the first embodiment is used (corresponding to claims 8 to 10).
The output of the light receiving element 113 is processed by a signal processing device 114 controlled by the central processing unit 111 and converted into digital image information. That is, such a digital camera includes means for converting a captured image (subject image) into digital image information. This means substantially controls the light receiving element 113, the signal processing device 114, and these. Central processing unit (CPU) 111 and the like.

The image information digitized by the signal processing device 114 is recorded in a semiconductor memory 115 such as a nonvolatile memory after being subjected to predetermined image processing in the image processing device 112 which is also controlled by the central processing unit 111. In this case, the semiconductor memory 115 may be a memory card loaded in the memory card slot 109 or a semiconductor memory built in the camera body (on-board). The liquid crystal monitor 107 can display an image being photographed, or can display an image recorded in the semiconductor memory 115. The image recorded in the semiconductor memory 115 can also be transmitted to the outside via a communication card 116 or the like loaded in a communication card slot (not shown).
When the camera is carried, the objective surface of the photographic lens 101 is covered with a lens barrier (not shown). When the user operates the power switch 106 to turn on the power, the lens barrier is opened and the objective surface is The structure is exposed. At this time, in the lens barrel of the photographing lens 101, the optical systems of the respective groups constituting the zoom lens are arranged at, for example, a short focal end (wide angle end), and each zoom switch 110 is operated by operating the zoom switch 110. The arrangement of the group optical system is changed, and the zooming operation to the long focal end (telephoto end) can be performed via the intermediate focal length. It is desirable that the optical system of the optical finder 102 is also scaled in conjunction with the change in the angle of view of the photographing lens 101.

In many cases, focusing is performed by half-pressing the shutter button 104. Focusing in the zoom lens according to the present invention (the zoom lens defined in claims 1 to 10 or shown in the first to fifth embodiments described above) is one of a plurality of optical systems constituting the zoom lens. This can be done by moving a group of parts or moving a light receiving element. When the shutter button 104 is further pushed down to the fully depressed state, photographing is performed, and then the processing as described above is performed.
When the image recorded in the semiconductor memory 115 is displayed on the liquid crystal monitor 107 or transmitted to the outside via the communication card 116 or the like, the operation button 108 is operated as specified. The semiconductor memory 115 and the communication card 116 are used by being loaded into dedicated or general-purpose slots such as the memory card slot 109 and the communication card slot, respectively.
As described above, in the digital camera (imaging device) or information device as described above, the photographic lens 101 configured using the zoom lens as described in the first embodiment is used as the imaging optical system. can do. Therefore, it is possible to realize a small digital camera (imaging device) or information device with high image quality using light receiving elements having 10 million to 15 million pixels or more.
Also, it can be applied as a zoom photographing lens of a silver salt camera and a projection lens of a projector.

G1 first lens group (positive)
G2 Second lens group (negative)
G3 Third lens group (negative)
G4 4th lens group (positive)
G5 5th lens group (positive)
L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11 1st lens, 2nd lens, 3rd lens, 4th lens, 5th lens, 6th lens, 7th lens, 1st lens 8 lens, 9th lens, 10th lens, 11th lens AD Aperture stop MF Parallel plate 101 Shooting lens 102 Optical viewfinder 103 Strobe (flash light)
104 Shutter button 105 Camera body 106 Power switch 107 Liquid crystal monitor 108 Operation button 109 Memory card slot 110 Zoom switch 111 Central processing unit (CPU)
112 Image processing device 113 Light receiving element 114 Signal processing device 115 Semiconductor memory 116 Communication card, etc.

JP-A-3-228008 Japanese Patent Laid-Open No. 10-48518 Japanese Patent Laid-Open No. 11-44848 JP 2000-28923 A JP 2010-175594 A

Claims (10)

In order from the object side to the image side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a negative refractive power, And a succeeding group constituted by one lens group, and during zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the second lens group and the second lens group The distance between the third lens group increases, the distance between the third lens group and the subsequent group changes, and focusing is performed by the third lens group, and the following conditional expressions (1), (2), (3 Zoom lens characterized by satisfying
(1) 2.0 <F3 / F23t <3.0
(2) -2.5 <F2 / Fm <-1.0
(3) -1.4 <F3 / Fm <-0.5
Where F2 is the focal length of the second lens group, F3 is the focal length of the third lens group, and F23t is a combination of the second lens group and the third lens group at the telephoto end. The focal length of the entire system at the wide-angle end is Fw, the focal length of the entire system at the telephoto end is Ft, and Fm = √ (Fw × Ft).   The zoom lens according to claim 1, wherein the third lens group includes one negative lens. The zoom lens according to claim 1 or 2, wherein the one negative lens of the third lens group satisfies the following conditional expression (4).
(4) νd> 50
Where νd is the Abbe number of the one negative lens in the third lens group.   4. The zoom lens according to claim 1, wherein the subsequent group includes an aperture stop, a fourth lens group having a positive refractive power, and a positive refractive power from the object side to the image side. A zoom lens comprising: a fifth lens group having a first lens group and a second lens group.   5. The zoom lens according to claim 1, wherein all the lens groups are configured to move during zooming. 6. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression (5).
(5) 0.75 <Y ′ / Fw
Where Y ′ is the maximum image height and Fw is the focal length of the entire system at the wide-angle end. The zoom lens according to any one of claims 1 to 6, wherein the following conditional expression (6) is satisfied.
(6) 3.0 <Ft / Fw
Where Ft is the focal length of the entire system at the telephoto end, and Fw is the focal length of the entire system at the wide-angle end.   An information device having a photographing function, comprising the zoom lens according to claim 1 as a photographing optical system.   9. The information apparatus according to claim 8, wherein an object image formed by the zoom lens is formed on a light receiving surface of the image sensor.   A portable information terminal device comprising: the zoom lens according to claim 1 as a photographing optical system of a photographing function unit.

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