JP2014035390A - Zoom lens, camera, and portable information terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens capable of achieving a resolution corresponding to a small imaging element of 10 million to 20 million pixels while a half field angle at a short focal end is 42 degrees or more, an f-number at a short focal end is 2.0 or less, an f-number at a long focal end is about 3.0, and the number of lenses is small.SOLUTION: A zoom lens is constituted by arranging, in order from an object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, and a positive fourth lens group G4. When varying power from the short focal end to the long focal end, the first lens group G1 is moved so as to be convex to an image plane side, the second lens group G2 is moved to the image plane side, the third lens group G3 is moved to the object side, and the fourth lens group G4 is moved. An aperture diaphragm AD is disposed between the second lens group G2 and the third lens group G3 and operated so as to move independently, when varying power from the short focal end to the long focal end. The first lens group G1 is constituted of negative and positive lenses and the second lens group G2 is constituted of negative, negative, negative, and positive lenses.

Description

  The present invention relates to a lens having a zooming function for changing the angle of view by changing the focal length, and is particularly suitable for a so-called digital camera or video camera that obtains digital image data of a subject using a solid-state imaging device. The present invention relates to a zoom lens, a camera using such a zoom lens as a photographing optical system, and a portable information terminal device having such a photographing function.

The market for digital cameras has become very large, and the demands of users for digital cameras are also diverse. In particular, high image quality and miniaturization are always desired by users, and occupy a great demand for users' digital cameras. For this reason, zoom lenses used as photographing lenses are also required to have both high performance and downsizing.
In terms of miniaturization, it is first necessary to shorten the total lens length (distance from the lens surface closest to the object side to the image plane) during use, and reduce the thickness of each lens group for storage. It is also important to reduce the overall length of the. Furthermore, in terms of high performance, it is necessary to have a resolving power corresponding to an image sensor with 10 to 20 million pixels over the entire zoom range over the entire zoom range.
In addition, there are many users who wish to widen the angle of view of the taking lens, and it is desirable that the half angle of view at the short focal point of the zoom lens is 42 degrees or more.
Furthermore, a large aperture is desired, and it is desirable that the F number at the short focal end is 2.0 or less.

Although there are many types of zoom lenses for digital cameras, the first lens group is convex on the image plane side as a type suitable for a large aperture while ensuring a zoom ratio of about 4 times. There is a zoom lens in which the second lens group moves to the image plane side, the third lens group moves to the object side, and the fourth lens group moves.
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. As a conventional example of a zoom lens in which a lens group is arranged and the second lens group is constituted by a negative lens, a negative lens, and a positive lens, JP 2010-139705 A (hereinafter referred to as “Patent Document 1”). JP 2009-223008 A (hereinafter referred to as “Patent Document 2”), JP 2000-347102 A (hereinafter referred to as “Patent Document 3”), and the like.
These zoom lenses described in Patent Document 1, Patent Document 2, and Patent Document 3 have a large zoom ratio, but cannot be said to be sufficiently small because the F number at the short focal end is 2.5 or more.
The zoom lens described in Patent Document 3 has a wide angle of view at the short focal point of about 40 °, but it cannot be said to be sufficiently small in terms of miniaturization.
Further, the zoom lenses described in Patent Document 1 and Patent Document 2 cannot be said to have a sufficiently wide angle of view at the short focal end.

  The present invention has been made in view of the above-described circumstances, and the invention according to claim 1 is such that the half field angle at the short focus end is 42 degrees or more and the angle at the short focus end is sufficiently wide. A zoom lens having a number of 2.0 or less, an F number at the long focal length of about 3.0, a constitutional number of about 12 to 13, and a compact and resolving power corresponding to an image sensor with 10 to 20 million pixels The purpose is to provide.

In order to achieve the above object, a zoom lens according to claim 1 is provided.
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. When zooming from the short focal end to the long focal end, the first lens group moves so as to be convex toward the image side, the second lens group moves toward the image side, and the third lens group In a zoom lens that moves to the object side and moves the fourth lens group, an aperture stop is disposed between the second lens group and the third lens group, and the first lens group is negative in order from the object side. The second lens group includes, in order from the object side, a negative lens L21, a negative lens L22, a negative lens L23, and a positive lens L24, and the following conditional expression:
0.5 <| f2 / ft | <0.7 (1)
It is characterized by that.

According to the invention of claim 1,
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. When zooming from the short focal end to the long focal end, the first lens group moves so as to be convex toward the image side, the second lens group moves toward the image side, and the third lens group In the zoom lens that moves to the object side and the fourth lens group moves, an aperture stop is disposed between the second lens group and the third lens group, and the first lens group is sequentially from the object side. The second lens group includes, in order from the object side, a negative lens L21, a negative lens L22, a negative lens L23, and a positive lens L24.
The focal length of the second lens group is f2, and the focal length of the entire system at the long focal end is ft.
The following conditional expression:
0.5 <| f2 / ft | <0.7 (1)
By satisfying, in particular,
Although the short focus end has a sufficiently wide angle of view of 42 degrees or more, the short focus end F number is 2.0 or less, the long focus end F number is 3.0 or less, and the number of components is 12. A zoom lens having a resolving power corresponding to an image sensor with a small size of about 13 to 13 pixels and a size of 10 to 20 million pixels can be provided. Thus, it is possible to realize a camera and a portable information terminal device having a zooming area that covers the above.

1 is a diagram illustrating a configuration of an optical system of a zoom lens according to a first embodiment of the present invention and a zoom locus associated with zooming, where (a) is a short focal end (wide angle end / wide), ( b) is an intermediate focal length (Mean), and (c) is a sectional view along the optical axis at each of the long focal ends (telephoto end / tele). FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal end (wide angle end) of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the intermediate focal length of the zoom lens according to Example 1 of the present invention shown in FIG. 1. FIG. 3 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end (telephoto end) of the zoom lens according to Embodiment 1 of the present invention shown in FIG. 1. FIG. 6 is a diagram illustrating a configuration of an optical system of a zoom lens according to a second embodiment of the present invention and a zoom locus associated with zooming, in which (a) is a short focal end (wide angle end / wide), ( b) is an intermediate focal length (Mean), and (c) is a sectional view along the optical axis at each of the long focal ends (telephoto end / tele). FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma at the short focal end (wide angle end) of the zoom lens according to Embodiment 2 of the present invention shown in FIG. 5. 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 Example 2 of the present invention shown in FIG. 5. FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma at the long focal end (telephoto end) of the zoom lens according to Embodiment 2 of the present invention shown in FIG. 5. It is a figure which shows the zoom locus | trajectory accompanying the structure and zooming zoom of the optical system of the zoom lens which concerns on the 3rd Embodiment of this invention, and Example 3, (a) is a short focus end (wide-angle end and Wide), ( b) is an intermediate focal length (Mean), and (c) is a sectional view along the optical axis at each of the long focal ends (telephoto end / tele). FIG. 10 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the short focal end (wide angle end) of the zoom lens according to Example 3 illustrated in FIG. 9; FIG. 10 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 3 illustrated in FIG. 9. FIG. 10 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end (telephoto end) of the zoom lens according to Example 3 illustrated in FIG. 9; FIG. 10 is a diagram illustrating a configuration of an optical system of a zoom lens according to a fourth embodiment of the present invention and a zoom locus associated with zooming, in which (a) is a short focal end (wide angle end / wide), ( b) is an intermediate focal length (Mean), and (c) is a sectional view along the optical axis at each of the long focal ends (telephoto end / tele). FIG. 14 is an aberration curve diagram showing spherical aberration, astigmatism, distortion aberration, and coma aberration at the short focal end (wide angle end) of the zoom lens according to Example 4 illustrated in FIG. 13; FIG. 14 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 4 illustrated in FIG. 13. FIG. 14 is an aberration curve diagram showing spherical aberration, astigmatism, distortion and coma aberration at the long focal end (telephoto end) of the zoom lens according to Embodiment 4 of the present invention shown in FIG. 13; It is the perspective view seen from the object side which shows typically the external appearance structure of the digital camera as an imaging device 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, a camera, 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 (numerical examples), first, a fundamental embodiment of the present invention will be described.
The zoom lenses according to the first to fourth embodiments of the present invention, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive lens And a fourth lens group having a positive refractive power, and the first lens group is convex toward the image side upon zooming from the short focal end to the long focal end. A zoom lens in which the second lens group moves to the image side, the third lens group moves to the object side, and the fourth lens group moves,
Furthermore, each has the following characteristics.
That is, the first feature of the zoom lens according to the first to fourth embodiments of the present invention is that an aperture stop is disposed between the second lens group and the third lens group, and the first lens The zoom lens is composed of a negative lens and a positive lens in order from the object side, and the second lens group is composed of a negative lens L21, a negative lens L22, a negative lens L23, and a positive lens L24 in order from the object side.
Furthermore, it has the following features.
A zoom lens constituted by four positive, negative, positive and positive lens groups as in the present invention is configured as a so-called variator in which the third lens group bears a main zooming action.
Upon zooming from the short focal end to the long focal end, the first lens unit moves so as to be convex toward the image side, the second lens unit moves toward the image side, and the third lens unit moves toward the object side. When the fourth lens group is moved, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is decreased, so that the second lens group and the third lens group are moved. Both magnifications (absolute values) of the lens group increase and share the zooming action.
Furthermore, in the zoom lens according to the present invention, the first lens unit is moved so as to be convex toward the image side, so that the entire length is secured even at the short focal point, and the high performance is achieved while having a wide angle and a large aperture. It is trying to become. However, since the second lens group is separated from the stop at the short focal end, the second lens group becomes large, and it becomes difficult to correct aberrations in the second lens group. Therefore, when the second lens group is composed of a negative lens, a negative lens, and a positive lens, the image side surface of the second lens group closest to the object side negative lens tends to be a semicircular configuration, and high productivity cannot be expected. . In addition, aberration correction becomes difficult. Therefore, the second lens group is configured in the order of the negative lens L21, the negative lens L22, the negative lens L23, and the positive lens L24 from the object side.

By making the negative lens L21 and the negative lens L22 into a meniscus shape convex toward the object side and making the negative lens L23 into a concave shape toward the object side, various aberrations can be corrected in a balanced manner.
Further, the focal length of the second lens group is f2, and the focal length of the entire system at the long focal end is ft.
The following conditional expression:
0.5 <| f2 / ft | <0.7 (1)
Is preferably satisfied (corresponding to claim 1).
When the upper limit value of the conditional expression is exceeded, the focal length of the second lens group becomes too long, the zooming effect by the second lens group becomes too small, and it becomes difficult to correct aberrations in the entire zoom range. If the lower limit value of conditional expression (1) is not reached, the focal length of the second lens group becomes too short, and it becomes difficult to correct aberrations in the second lens group.
For higher performance, the focal length of the first lens group is f1, and the focal length of the entire system with a long focal length is ft.
3.0 <f1 / ft <4.0 (2)
Is preferably satisfied (corresponding to claim 2).

  If the upper limit value of the conditional expression (2) is exceeded, it will be difficult to ensure the zooming function by the second lens group, and it will be difficult to correct aberrations in the entire zoom range. If the lower limit of conditional expression (2) is not reached, the focal length of the first lens group becomes too short, making it difficult to correct aberrations in the first lens group.

In order to achieve high performance while being small, the thickness on the optical axis of the first lens group is D1, and the thickness on the optical axis of the second lens group is D2.
0.3 <D1 / D2 <0.5 (3)
Is satisfied (corresponding to claim 3).
When the upper limit value of conditional expression (3) is exceeded, the second lens group becomes too thin and aberration correction in the second lens group becomes difficult, or the first lens group becomes too thick and the size increases. If the lower limit value of conditional expression (3) is not reached, the second lens group becomes too thick, the air interval for zooming becomes too small, and it becomes difficult to correct aberrations in the entire zoom range.
For higher performance, the focal length of the negative lens L21 of the second lens group is f2_1, and the focal length of the negative lens L22 of the second lens group is f2_2.
0.4 <f2_1 / f2_2 <0.8 (4)
Is satisfied (corresponding to claim 4).
Even if the upper limit value of conditional expression (4) is exceeded or less than the lower limit value, it is difficult to correct aberrations by sharing the negative lens L21 and the negative lens L22.

In order to achieve higher performance, the air distance between the negative lens L22 and the negative lens L23 of the second lens group is Da, and the thickness on the optical axis of the second lens group is D2.
0.3 <Da / D2 <0.5 (5)
Is satisfied (corresponding to claim 5).
In order to achieve high performance while being small, the negative lens L22 of the second lens group may be an aspherical lens (corresponding to claim 6). Distortion can be sufficiently corrected by making the negative lens L22 an aspherical surface. Although the distortion can be corrected even if the negative lens L21 is aspherical, the cost increases because the effective diameter of the negative lens L21 is large. Therefore, it is better to make L22 an aspherical surface.
In order to achieve higher performance, the effective ray height of the negative lens L21 of the second lens group is set to H212, and the radius of curvature of the negative lens L21 of the second lens group is set to R212.
0.7 <H212 / R212 <0.9 (6)
Is satisfied (corresponding to claim 7).

If the upper limit value of conditional expression (6) is exceeded, off-axis rays at the short focal end will be greatly refracted, making it difficult to sufficiently correct aberrations. If the lower limit value of conditional expression (6) is not reached, the power of the negative lens L21 becomes too weak, and it is difficult to correct aberrations by sharing with the negative lens L22.
In order to further reduce the size and increase the performance, the distance between the aperture stop and the third lens group at the short focus end is TLs3_w, and the distance between the second lens group and the aperture stop at the short focus end is TL2s_w.
0.15 <TLs3_w / TL2s_w <0.40 (7)
It is desirable to satisfy
If the lower limit value of the conditional expression (7) is not reached, the distance between the second lens group and the aperture stop becomes large, and the off-axis ray passing through the second lens group at the short focal point becomes too high. Correction of off-axis aberrations becomes difficult, and the second lens group becomes large. When the upper limit value of conditional expression (7) is exceeded, the distance between the third lens group and the aperture stop becomes large, and the off-axis rays passing through the third lens group at the short focal end become too high, and the third lens group. Aberration correction becomes difficult, and the third lens group becomes large.
When it is necessary to reduce the amount of light reaching the image plane, the aperture stop diameter may be reduced. However, if the amount of light is reduced by inserting an ND filter or the like without greatly changing the stop diameter, it is caused by the diffraction phenomenon. It is preferable because a decrease in resolution can be prevented.

Embodiments and specific numerical examples of the zoom lens according to the present invention will be described below.
Examples 1 to 4 according to the first to fourth embodiments have a four-group configuration of positive, negative and positive.
In each embodiment, the parallel flat plate FM disposed on the image plane side of the fourth lens group includes various filters such as an optical low-pass filter and an infrared cut filter, and a cover glass (seal glass) of a light receiving element such as a CMOS sensor. Is assumed.
The lens material is all optical glass in all the examples. However, since the lens of the fourth lens group does not greatly affect the image quality due to surface accuracy, a resin lens may be used.
The aberration in each example is sufficiently corrected, and can correspond to a light receiving element with 10 to 20 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.
Although distortion aberration can be corrected electronically, the correction has an effect on image quality. In the present invention, high image quality is achieved by optically correcting distortion aberration sufficiently.

The meanings of symbols in each embodiment are as follows.
f: the focal length F of the entire system: F number omega: half field angle R: curvature radius D: surface interval N _d: refractive index [nu _d: Abbe number K: aspherical conic constant A _4: 4-order aspheric coefficients A ₆ : 6th-order aspheric coefficient A ₈ : 8th-order aspheric coefficient A ₁₀ : 10th-order aspheric coefficient However, the aspheric surface used here is the reciprocal (paraxial curvature) of the paraxial radius of curvature. When the height from the optical axis is H, it is defined by the following equation (8).

FIG. 1 shows a configuration of an optical system of a zoom lens according to a first embodiment of the present invention and a telephoto end (long focal end) through a predetermined intermediate focal length from a wide angle end (short focal end). 4A and 4B show zoom trajectories associated with zooming, (a) is a cross-sectional view along the optical axis at the wide-angle end (short focal end), (b) is a cross-sectional view along the optical axis at the intermediate focal length, and (c) ) Is a cross-sectional view along the optical axis at the telephoto end (long focal end). In FIG. 1 showing the lens group arrangement of Example 1, the left side in the figure is the object (subject) side.
The zoom lens shown in FIG. 1 includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side to the image plane side along the optical axis. A third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. Among these, the first lens group G1 includes two first lenses L11 and L12, and the second lens group G2 includes the first lens L21, the second lens L22, the third lens L23, and the fourth lens L2. The third lens group G3 includes a first lens L31, a second lens L32, a third lens L33, a fourth lens L34, a fifth lens L35, and a sixth lens L36. The fourth lens group G4 has one first lens L41.

The first lens group G1 to the fourth lens group G4 are supported by a common support frame or the like that is appropriate for each group, operate relatively for each group during zooming and the like, and the aperture stop AD is the second aperture stop AD. It is disposed between the lens group G2 and the third lens group G3, and operates to move independently upon zooming from the short focus end to the long focus end. FIG. 1 also shows surface numbers (R1 to R26) of the respective optical surfaces.
At the time of zooming from the wide angle end (short focal end) to the telephoto end (long focal end), all the first lens group G1 to fourth lens group G4 move, and the first lens group G1 has an image plane. The second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the second lens group G2 to the convex side. The distance between the first lens group G1 and the second lens group G2 is increased, and the distance between the second lens group G2 and the third lens group G3 is decreased.
The first lens group G1 includes a first lens (negative lens) made of a negative meniscus lens having a convex surface facing the object side, and a second lens (positive lens) L12 made of a positive meniscus lens having a convex surface facing the object side. The two lenses, the first lens L11 and the second lens L12, are closely bonded to each other and bonded together to form a cemented lens composed of two lenses. The second lens group G2 is a first lens (negative lens) L21 including a negative meniscus lens having a convex surface directed toward the object side in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, and the image surface side. A second lens (negative lens) L22 made of an aspheric lens having an aspherical surface formed thereon, a third lens (negative lens) L23 made of a negative meniscus lens having a convex surface facing the image surface side, and an object side from the image surface side. A fourth lens (positive lens) L24 composed of a biconvex lens having a convex surface with a large curvature is disposed.

The third lens group G3 is a biconvex lens in which a convex surface having a curvature that is stronger than the image surface side is directed to the object side sequentially from the object side, and a first lens (positive lens) having aspheric surfaces formed on both surfaces. Lens) L31, a second lens (positive lens) L32 made of a positive meniscus lens having a convex surface facing the object side, a third lens (negative lens) L33 made of a negative meniscus lens having a convex surface facing the object side, and an image A fourth lens (positive lens) L34 made of a positive meniscus lens having a convex surface facing the surface side, and a fifth lens (negative lens) L35 made of a biconcave lens having a concave surface having a larger curvature than the image surface side on the object side. A sixth lens (positive lens) L36, which is a positive meniscus lens having a convex surface facing the surface side and an aspherical surface having an aspheric surface formed on the image surface side, is disposed. Lens L The two lenses No. 3 and the two lenses, the fourth lens L34 and the fifth lens L35, are closely bonded to each other and bonded together to form a cemented lens composed of two lenses. Yes.
The fourth lens group G4 includes a first lens (positive lens) L41 made of a positive meniscus lens having a convex surface directed toward the object side.

In this case, as shown in FIG. 1, when zooming from the wide-angle end (short focal end) to the telephoto end (long focal end), the first lens group G1 moves so as to be convex toward the image plane side. The second lens group G2 moves to the image plane side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the first lens group G1 and the second lens group G2. The interval increases, the interval between the second lens group G2 and the third lens group G3 decreases, and both the magnifications (absolute values) of the second lens group G2 and the third lens group G3 increase.
Therefore, the configuration of the third lens group G3 includes a positive lens (first lens L31), a positive lens (second lens L32), a negative lens (third lens L33), and a positive lens (first lens having a convex surface facing the image plane side). 4 lens L34), a biconcave lens (fifth lens L35) having a concave surface with a larger curvature than the image surface side on the object side, and a positive meniscus lens (sixth lens L36) having a convex surface on the image surface side.
In Example 1, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 5.29 to 22.00, F = 1.85 to 2.87, ω by zooming, respectively. = Varies in the range of 43.89 to 12.31. The optical characteristics of each optical element are as shown in Table 1 below.

表１において、面番号に「＊（アスタリスク）」を付して示した面番号のレンズ面が非球面であり、また、ガラスの表示欄の硝種名の後の括弧内に、次の通り硝材の製造メーカー名を、ＨＯＹＡ（ＨＯＹＡ株式会社）、ＯＨＡＲＡ（株式会社オハラ）、ＨＩＫＡＲＩ（光ガラス株式会社）として略記した。これらは、他の実施例についても同様である。
すなわち、表１においては、「＊」が付された第７面、第１３面、第１４面および第２２面の各光学面が非球面であり、式（８）における各非球面のパラメータは、下記の表２の通りである。

In Table 1, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspheric surface, and the glass material in the parentheses after the glass type name in the glass display column is as follows. Are abbreviated as HOYA (HOYA Corporation), OHARA (Ohara Corporation), and HIKARI (Hikari Glass Corporation). The same applies to the other embodiments.
That is, in Table 1, the optical surfaces of the seventh surface, the thirteenth surface, the fourteenth surface, and the twenty-second surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation (8) are Table 2 below.

第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔ＤＡ、第２レンズ群Ｇ２と開口絞りＡＤとの間の可変間隔ＤＢ、開口絞りＡＤと第３レンズ群Ｇ３との間の可変間隔ＤＣ、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔ＤＤ、そして第４レンズ群Ｇ４とフィルタ等の平行平板ＦＭとの間の可変間隔ＤＥは、ズーミングに伴って表３のように変化させられる。

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 aperture stop AD, and the variable distance between the aperture stop AD and the third lens group G3. The distance DC, the variable distance DD between the third lens group G3 and the fourth lens group G4, and the variable distance DE between the fourth lens group G4 and the parallel plate FM such as a filter are shown in Table 3 along with zooming. It can be changed as follows.

したがって、条件式（１）〜条件式（７）に対応する値は、次表（４）のようになり、それぞれ条件式（１）〜条件式（７）を満足している。

Therefore, the values corresponding to the conditional expressions (1) to (7) are as shown in the following table (4), and satisfy the conditional expressions (1) to (7), respectively.

  2, FIG. 3, and FIG. 4 show aberration diagrams of spherical aberration, astigmatism, distortion, and coma aberration at the wide-angle end, the intermediate focal length, and the telephoto end, respectively, in Example 1. In these drawings, a broken line in spherical aberration represents a sine condition, a solid line in astigmatism represents sagittal, and a broken line represents meridional. In addition, g and d in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent g-line and d-line, respectively. The same applies to the aberration diagrams of the other examples.

FIG. 5 shows the configuration of the optical system of the zoom lens according to the second embodiment of the present invention and Example 2, and the telephoto end (long focal end) through a predetermined intermediate focal length from the wide angle end (short focal end). 4A and 4B show zoom trajectories associated with zooming, (a) is a cross-sectional view along the optical axis at the wide-angle end (short focal end), (b) is a cross-sectional view along the optical axis at the intermediate focal length, and (c) ) Is a cross-sectional view along the optical axis at the telephoto end (long focal end). In FIG. 5 showing the lens group arrangement of Example 2, the left side in the figure is the object (subject) side.
The zoom lens shown in FIG. 5 has a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power sequentially from the object side to the image plane side along the optical axis. A third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. Among these, the first lens group G1 includes two first lenses L11 and L12, and the second lens group G2 includes the first lens L21, the second lens L22, the third lens L23, and the fourth lens L2. The third lens group G3 includes a first lens L31, a second lens L32, a third lens L33, a fourth lens L34, a fifth lens L35, and a sixth lens L36. The fourth lens group G4 has one first lens L41.

The first lens group G1 to the fourth lens group G4 are supported by a common support frame or the like that is appropriate for each group, operate relatively for each group during zooming and the like, and the aperture stop AD is the second aperture stop AD. It is disposed between the lens group G2 and the third lens group G3, and operates to move independently upon zooming from the short focus end to the long focus end. FIG. 5 also shows surface numbers (R1 to R26) of the optical surfaces.
At the time of zooming from the wide angle end (short focal end) to the telephoto end (long focal end), all the first lens group G1 to fourth lens group G4 move, and the first lens group G1 has an image plane. The second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the second lens group G2 to the convex side. The distance between the first lens group G1 and the second lens group G2 is increased, and the distance between the second lens group G2 and the third lens group G3 is decreased.
The first lens group G1 includes a first lens (negative lens) made of a negative meniscus lens having a convex surface facing the object side, and a second lens (positive lens) L12 made of a positive meniscus lens having a convex surface facing the object side. The two lenses, the first lens L11 and the second lens L12, are closely bonded to each other and bonded together to form a cemented lens composed of two lenses. The second lens group G2 is a first lens (negative lens) L21 including a negative meniscus lens having a convex surface directed toward the object side in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, and the image surface side. A second lens (negative lens) L22 made of an aspheric lens having an aspherical surface formed thereon, a third lens (negative lens) L23 made of a negative meniscus lens having a convex surface facing the image surface side, and an object side from the image surface side. A fourth lens (positive lens) L24 composed of a biconvex lens having a convex surface with a large curvature is disposed.

The third lens group G3 is a biconvex lens in which a convex surface having a curvature that is stronger than the image surface side is directed to the object side sequentially from the object side, and a first lens (positive lens) having aspheric surfaces formed on both surfaces. Lens) L31, a second lens (negative lens) L32 made of a negative meniscus lens having a convex surface facing the object side, a third lens (negative lens) L33 made of a negative meniscus lens having a convex surface facing the object side, and an image A fourth lens (positive lens) L34 made of a positive meniscus lens having a convex surface facing the surface side, and a fifth lens (negative lens) L35 made of a biconcave lens having a concave surface having a larger curvature than the image surface side on the object side. A positive meniscus lens having a convex surface having a larger curvature than the object side on the surface side and a sixth lens (positive lens) L36 formed of an aspheric lens having an aspheric surface on the image surface side; 2 len The two lenses L32 and the third lens L33 and the four lenses L34 and the fifth lens L35 are bonded in close contact with each other, and are joined together to form a joint composed of two lenses. A lens is formed.
The fourth lens group G4 includes a first lens (positive lens) L41 made of a positive meniscus lens having a convex surface directed toward the object side.

In this case, as shown in FIG. 5, when zooming from the wide-angle end (short focal end) to the telephoto end (long focal end), the first lens group G1 moves so as to be convex toward the image plane side. The second lens group G2 moves to the image plane side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the first lens group G1 and the second lens group G2. The interval increases, the interval between the second lens group G2 and the third lens group G3 decreases, and both the magnifications (absolute values) of the second lens group G2 and the third lens group G3 increase.
Therefore, the configuration of the third lens group G3 includes a positive lens (first lens L31), a negative lens (second lens L32), a positive lens (third lens L33), and a positive lens (first lens having a convex surface facing the image plane side). 4 lens L34), a biconcave lens (fifth lens L35) having a concave surface having a larger curvature than the image surface side on the object side, and a positive meniscus lens (sixth lens L36) having a convex surface on the object side.
In Example 2, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 5.29 to 22.01, F = 1.85 to 2.84, ω by zooming, respectively. = It changes in the range of 44.06-12.30. The optical characteristics of each optical element are as shown in Table 5 below.

表５において、面番号に「＊（アスタリスク）」を付して示した面番号のレンズ面が非球面であり、また、ガラスの表示欄の硝種名の後の括弧内に、次の通り硝材の製造メーカー名を、ＨＯＹＡ（ＨＯＹＡ株式会社）、ＯＨＡＲＡ（株式会社オハラ）、ＨＩＫＡＲＩ（光ガラス株式会社）として略記した。これらは、他の実施例についても同様である。
すなわち、表５においては、「＊」が付された第７面、第１３面、第１４面および第２２面の各光学面が非球面であり、式（８）における各非球面のパラメータは、下記の表６の通りである。

In Table 5, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspheric surface, and the glass material in the parentheses after the glass type name in the glass display column is as follows. Are abbreviated as HOYA (HOYA Corporation), OHARA (Ohara Corporation), and HIKARI (Hikari Glass Corporation). The same applies to the other embodiments.
That is, in Table 5, the optical surfaces of the seventh surface, the thirteenth surface, the fourteenth surface, and the twenty-second surface marked with “*” are aspheric surfaces, and the parameters of each aspheric surface in the equation (8) are Table 6 below.

第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔ＤＡ、第２レンズ群Ｇ２と開口絞りＡＤとの間の可変間隔ＤＢ、開口絞りＡＤと第３レンズ群Ｇ３との間の可変間隔ＤＣ、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔ＤＤ、そして第４レンズ群Ｇ４とフィルタ等の平行平板ＦＭとの間の可変間隔ＤＥは、ズーミングに伴って表７のように変化させられる。

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 aperture stop AD, and the variable distance between the aperture stop AD and the third lens group G3. The distance DC, the variable distance DD between the third lens group G3 and the fourth lens group G4, and the variable distance DE between the fourth lens group G4 and the parallel plate FM such as a filter are shown in Table 7 along with zooming. It can be changed as follows.

したがって、条件式（１）〜条件式（７）に対応する値は、次表（８）のようになり、それぞれ条件式（１）〜条件式（７）を満足している。

Therefore, the values corresponding to the conditional expressions (1) to (7) are as shown in the following table (8), and satisfy the conditional expressions (1) to (7), respectively.

  6, FIG. 7, and FIG. 8 show aberration diagrams of spherical aberration, astigmatism, distortion, and coma aberration at the wide-angle end, intermediate focal length, and telephoto end, respectively, in Example 2. In these drawings, a broken line in spherical aberration represents a sine condition, a solid line in astigmatism represents sagittal, and a broken line represents meridional. In addition, g and d in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent g-line and d-line, respectively. The same applies to the aberration diagrams of the other examples.

FIG. 9 shows the configuration of the optical system of the zoom lens according to the third embodiment of the present invention and Example 3, and the telephoto end (long focal end) through a predetermined intermediate focal length from the wide angle end (short focal end). 4A and 4B show zoom trajectories associated with zooming, (a) is a cross-sectional view along the optical axis at the wide-angle end (short focal end), (b) is a cross-sectional view along the optical axis at the intermediate focal length, and (c) ) Is a cross-sectional view along the optical axis at the telephoto end (long focal end). In FIG. 9 showing the lens group arrangement of the third embodiment, the left side in the figure is the object (subject) side.
The zoom lens shown in FIG. 9 includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power sequentially from the object side to the image plane side along the optical axis. A third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. Among these, the first lens group G1 includes two first lenses L11 and L12, and the second lens group G2 includes the first lens L21, the second lens L22, the third lens L23, and the fourth lens L2. The third lens group G3 includes the first lens L31, the second lens L32, the third lens L33, the fourth lens L34, and the fifth lens L35. The fourth lens group G4 includes the lens L24. Has one first lens L41.

The first lens group G1 to the fourth lens group G4 are supported by a common support frame or the like that is appropriate for each group, operate relatively for each group during zooming and the like, and the aperture stop AD is the second aperture stop AD. It is disposed between the lens group G2 and the third lens group G3, and operates to move independently upon zooming from the short focus end to the long focus end. FIG. 9 also shows the surface numbers (R1 to R24) of the optical surfaces.
At the time of zooming from the wide angle end (short focal end) to the telephoto end (long focal end), all the first lens group G1 to fourth lens group G4 move, and the first lens group G1 has an image plane. The second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the second lens group G2 to the convex side. The distance between the first lens group G1 and the second lens group G2 is increased, and the distance between the second lens group G2 and the third lens group G3 is decreased.
The first lens group G1 includes a first lens (negative lens) made of a negative meniscus lens having a convex surface facing the object side, and a second lens (positive lens) L12 made of a positive meniscus lens having a convex surface facing the object side. The two lenses, the first lens L11 and the second lens L12, are closely bonded to each other and bonded together to form a cemented lens composed of two lenses. The second lens group G2 is a first lens (negative lens) L21 including a negative meniscus lens having a convex surface directed toward the object side in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, and the image surface side. A second lens (negative lens) L22 made of an aspheric lens having an aspherical surface formed thereon, and a third lens (negative lens) L23 made of a biconcave lens having a concave surface having a larger curvature than the image surface side on the object side. A fourth lens (positive lens) L24 composed of a biconvex lens having a convex surface having a larger curvature than the image surface side is disposed.

The third lens group G3 is a biconvex lens in which a convex surface having a larger curvature than the image surface side is directed toward the object side in order from the object side, and a first lens (positive lens) having aspheric surfaces formed on both surfaces. Lens) L31, a second lens (positive lens) L32 made of a positive meniscus lens having a convex surface facing the object side, a third lens (negative lens) L33 made of a negative meniscus lens having a convex surface facing the object side, and an image A fourth lens (positive lens) L34 made of a positive meniscus lens having a convex surface facing the surface side, and a fifth lens (negative lens) L35 made of a negative meniscus lens having a convex surface facing the image surface side; The two lenses, the second lens L32 and the third lens L33, and the two lenses, the fourth lens L34 and the fifth lens L35, are bonded in close contact with each other and joined together. Form a cemented lens consisting of a lens.
The fourth lens group G4 is a positive meniscus lens having a convex surface directed toward the object side, and a first lens (positive lens) L41 including an aspheric lens having an aspheric surface formed on the object side.
In this case, as shown in FIG. 9, when zooming from the wide-angle end (short focal end) to the telephoto end (long focal end), the first lens group G1 moves so as to be convex toward the image plane side. The second lens group G2 moves to the image plane side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the first lens group G1 and the second lens group G2. The interval increases, the interval between the second lens group G2 and the third lens group G3 decreases, and both the magnifications (absolute values) of the second lens group G2 and the third lens group G3 increase.

Therefore, the configuration of the third lens group G3 includes a positive lens (first lens L31), a positive lens (second lens L32), a negative lens (third lens L33), and a positive lens (first lens having a convex surface facing the image plane side). 4 lens L34), and a negative meniscus lens (fifth lens L35) having a convex surface facing the image surface side.
In Example 3, the focal length f, F number F, and half angle of view ω of the entire optical system are f = 5.29 to 22.02, F = 2.00 to 3.10, ω by zooming, respectively. = Varies in the range of 43.95 to 12.46. The optical characteristics of each optical element are as shown in Table 9 below.

表９において、面番号に「＊（アスタリスク）」を付して示した面番号のレンズ面が非球面であり、また、ガラスの表示欄の硝種名の後の括弧内に、次の通り硝材の製造メーカー名を、ＨＯＹＡ（ＨＯＹＡ株式会社）、ＯＨＡＲＡ（株式会社オハラ）、ＨＩＫＡＲＩ（光ガラス株式会社）として略記した。これらは、他の実施例についても同様である。
すなわち、表９においては、「＊」が付された第７面、第１３面、第１４面および第２１面の各光学面が非球面であり、式（８）における各非球面のパラメータは、下記の表１０の通りである。

In Table 9, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspheric surface, and the glass material in the parentheses after the glass type name in the glass display column is as follows. Are abbreviated as HOYA (HOYA Corporation), OHARA (Ohara Corporation), and HIKARI (Hikari Glass Corporation). The same applies to the other embodiments.
That is, in Table 9, the optical surfaces of the seventh surface, the thirteenth surface, the fourteenth surface, and the twenty-first surface to which “*” is attached are aspherical surfaces. Table 10 below.

第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔ＤＡ、第２レンズ群Ｇ２と開口絞りＡＤとの間の可変間隔ＤＢ、開口絞りＡＤと第３レンズ群Ｇ３との間の可変間隔ＤＣ、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔ＤＤ、そして第４レンズ群Ｇ４とフィルタ等の平行平板ＦＭとの間の可変間隔ＤＥは、ズーミングに伴って表１１のように変化させられる。

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 aperture stop AD, and the variable distance between the aperture stop AD and the third lens group G3. The distance DC, the variable distance DD between the third lens group G3 and the fourth lens group G4, and the variable distance DE between the fourth lens group G4 and the parallel plate FM such as a filter are shown in Table 11 along with zooming. It can be changed as follows.

したがって、条件式（１）〜条件式（７）に対応する値は、次表（１２）のようになり、それぞれ条件式（１）〜条件式（７）を満足している。

Accordingly, the values corresponding to the conditional expressions (1) to (7) are as shown in the following table (12), and satisfy the conditional expressions (1) to (7), respectively.

  FIGS. 10, 11 and 12 show aberration diagrams of spherical aberration, astigmatism, distortion and coma aberration at the wide-angle end, intermediate focal length and telephoto end, respectively, in Example 3. In these drawings, a broken line in spherical aberration represents a sine condition, a solid line in astigmatism represents sagittal, and a broken line represents meridional. In addition, g and d in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent g-line and d-line, respectively. The same applies to the aberration diagrams of the other examples.

FIG. 13 shows the configuration of the zoom lens optical system according to the fourth embodiment of the present invention and the telephoto end (long focal end) through a predetermined intermediate focal length from the wide angle end (short focal end). 4A and 4B show zoom trajectories associated with zooming, (a) is a cross-sectional view along the optical axis at the wide-angle end (short focal end), (b) is a cross-sectional view along the optical axis at the intermediate focal length, and (c) ) Is a cross-sectional view along the optical axis at the telephoto end (long focal end). In FIG. 13 showing the lens group arrangement of Example 4, the left side in the figure is the object (subject) side.
The zoom lens shown in FIG. 13 includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from the object side to the image plane side along the optical axis. A third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. Among these, the first lens group G1 includes two first lenses L11 and L12, and the second lens group G2 includes the first lens L21, the second lens L22, the third lens L23, and the fourth lens L2. The third lens group G3 includes the first lens L31, the second lens L32, the third lens L33, the fourth lens L34, and the fifth lens L35. The fourth lens group G4 includes the lens L24. Has one first lens L41.
The first lens group G1 to the fourth lens group G4 are supported by a common support frame or the like that is appropriate for each group, operate relatively for each group during zooming and the like, and the aperture stop AD is the second aperture stop AD. It is disposed between the lens group G2 and the third lens group G3, and operates to move independently upon zooming from the short focus end to the long focus end. FIG. 13 also shows the surface numbers (R1 to R24) of the optical surfaces.

At the time of zooming from the wide angle end (short focal end) to the telephoto end (long focal end), all the first lens group G1 to fourth lens group G4 move, and the first lens group G1 has an image plane. The second lens group G2 moves to the image side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the second lens group G2 to the convex side. The distance between the first lens group G1 and the second lens group G2 is increased, and the distance between the second lens group G2 and the third lens group G3 is decreased.
The first lens group G1 includes a first lens (negative lens) made of a negative meniscus lens having a convex surface facing the object side, and a second lens (positive lens) L12 made of a positive meniscus lens having a convex surface facing the object side. The two lenses, the first lens L11 and the second lens L12, are closely bonded to each other and bonded together to form a cemented lens composed of two lenses. The second lens group G2 is a first lens (negative lens) L21 including a negative meniscus lens having a convex surface directed toward the object side in order from the object side, a negative meniscus lens having a convex surface directed toward the object side, and the image surface side. A second lens (negative lens) L22 made of an aspheric lens having an aspherical surface formed thereon, a third lens (negative lens) L23 made of a biconcave lens having a concave surface having a larger curvature than the image surface side on the object side, and an image. A fourth lens (positive lens) L24 made of a biconvex lens having a convex surface having a larger curvature than the object side is disposed on the surface side.

The third lens group G3 is a biconvex lens in which a convex surface having a larger curvature than the image surface side is directed toward the object side in order from the object side, and a first lens (positive lens) having aspheric surfaces formed on both surfaces. Lens) L31, a second lens (positive lens) L32 made of a positive meniscus lens having a convex surface facing the object side, a third lens (negative lens) L33 made of a negative meniscus lens having a convex surface facing the object side, and an image A fourth lens (positive lens) L34 made of a positive meniscus lens having a convex surface facing the surface side, and a fifth lens (negative lens) L35 made of a negative meniscus lens having a convex surface facing the image surface side; The two lenses, the second lens L32 and the third lens L33, and the two lenses, the fourth lens L34 and the fifth lens L35, are bonded in close contact with each other and joined together. Form a cemented lens consisting of a lens.
The fourth lens group G4 is a positive meniscus lens having a convex surface directed toward the object side, and a first lens (positive lens) L41 including an aspheric lens having an aspheric surface formed on the object side.
In this case, as shown in FIG. 13, at the time of zooming from the wide-angle end (short focal end) to the telephoto end (long focal end), the first lens group G1 moves so as to be convex toward the image plane side. The second lens group G2 moves to the image plane side, the third lens group G3 moves to the object side, and the fourth lens group G4 moves to move the first lens group G1 and the second lens group G2. The interval increases, the interval between the second lens group G2 and the third lens group G3 decreases, and both the magnifications (absolute values) of the second lens group G2 and the third lens group G3 increase.

Therefore, the configuration of the third lens group G3 includes a positive lens (first lens L31), a positive lens (second lens L32), a negative lens (third lens L33), and a positive lens (first lens having a convex surface facing the image plane side). 4 lens L34), and a negative meniscus lens (fifth lens L35) having a convex surface facing the image surface side.
In Example 4, the focal length f, the F number F, and the half angle of view ω of the entire optical system are f = 5.29 to 22.02, F = 1.93 to 2.97, ω, respectively, by zooming. = Varies in the range of 44.15 to 12.49. The optical characteristics of each optical element are as shown in Table 13 below.

表１３において、面番号に「＊（アスタリスク）」を付して示した面番号のレンズ面が非球面であり、また、ガラスの表示欄の硝種名の後の括弧内に、次の通り硝材の製造メーカー名を、ＨＯＹＡ（ＨＯＹＡ株式会社）、ＯＨＡＲＡ（株式会社オハラ）、ＨＩＫＡＲＩ（光ガラス株式会社）として略記した。これらは、他の実施例についても同様である。
すなわち、表１３においては、「＊」が付された第７面、第１３面、第１４面および第２１面の光学面が非球面であり、式（８）における各非球面のパラメータは、下記の表１４の通りである。

In Table 13, the lens surface with the surface number indicated by adding “* (asterisk)” to the surface number is an aspheric surface, and the glass material in the parentheses after the glass type name in the glass display column is as follows. Are abbreviated as HOYA (HOYA Corporation), OHARA (Ohara Corporation), and HIKARI (Hikari Glass Corporation). The same applies to the other embodiments.
That is, in Table 13, the optical surfaces of the seventh surface, the thirteenth surface, the fourteenth surface, and the twenty-first surface with “*” are aspheric surfaces, and the parameters of each aspheric surface in Equation (8) are as follows: It is as Table 14 below.

第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔ＤＡ、第２レンズ群Ｇ２と開口絞りＡＤとの間の可変間隔ＤＢ、開口絞りＡＤと第３レンズ群Ｇ３との間の可変間隔ＤＣ、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔ＤＤ、そして第４レンズ群Ｇ４とフィルタ等の平行平板ＦＭとの間の可変間隔ＤＥは、ズーミングに伴って表１５のように変化させられる。

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 aperture stop AD, and the variable distance between the aperture stop AD and the third lens group G3. The distance DC, the variable distance DD between the third lens group G3 and the fourth lens group G4, and the variable distance DE between the fourth lens group G4 and the parallel plate FM such as a filter are shown in Table 15 along with zooming. It can be changed as follows.

したがって、条件式（１）〜条件式（７）に対応する値は、次表（１６）のようになり、それぞれ条件式（１）〜条件式（７）を満足している。

Accordingly, the values corresponding to the conditional expressions (1) to (7) are as shown in the following table (16), and satisfy the conditional expressions (1) to (7), respectively.

FIGS. 14, 15 and 16 show aberration diagrams of spherical aberration, astigmatism, distortion and coma aberration at the wide-angle end, intermediate focal length and telephoto end, respectively, in Example 4. In these drawings, a broken line in spherical aberration represents a sine condition, a solid line in astigmatism represents sagittal, and a broken line represents meridional. In addition, g and d in the respective aberration diagrams of spherical aberration, astigmatism, and coma aberration represent g-line and d-line, respectively. The same applies to the aberration diagrams of the other examples.
Next, a digital camera as a camera according to the fifth embodiment of the present invention configured by adopting the zoom lens according to the first to fourth embodiments of the present invention as an imaging optical system will be described. This will be described with reference to FIGS. FIG. 17 is a perspective view schematically showing the external appearance of the digital camera viewed from the front side which 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 which 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. Also, an information device such as a so-called PDA (personal data assistant) or a portable information terminal device (sixth embodiment) 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 configurations as a digital camera. The zoom lens according to the present invention is used as an imaging optical system in such an information device. It may be adopted.

As shown in FIGS. 17 and 18, the digital camera includes a photographing lens 1, an optical viewfinder 2, a strobe (flashlight) 3, a shutter button 4, a camera body 5, a power switch 6, a liquid crystal monitor 7, an operation button 8, a memory. A card slot 9 and a zoom switch 10 are provided. Further, as shown in FIG. 19, the digital camera includes a central processing unit (CPU) 11, an image processing device 12, a light receiving element 13, a signal processing device 14, a semiconductor memory 15 and a communication card 16.
The digital camera includes a photographing lens 1 as an imaging optical system and a light receiving element 13 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 13 reads an optical image of a subject (object) formed by the photographing lens 1. As the photographing lens 1, the zoom lens according to the present invention as described in the first to fourth embodiments is used.
The output of the light receiving element 13 is processed by a signal processing device 14 controlled by the central processing unit 11 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, which substantially controls the light receiving element 13, the signal processing device 14, and these. And a central processing unit (CPU) 11 or the like.

The image information digitized by the signal processing device 14 is subjected to predetermined image processing in the image processing device 12 which is also controlled by the central processing unit 11 and then recorded in the semiconductor memory 15 such as a nonvolatile memory. In this case, the semiconductor memory 15 may be a memory card loaded in the memory card slot 9 or may be a semiconductor memory built in the camera body (onboard). The liquid crystal monitor 7 can display an image being shot, and can display an image recorded in the semiconductor memory 15. The image recorded in the semiconductor memory 15 can also be transmitted to the outside via a communication card 16 or the like loaded in a communication card slot (not shown).
When the camera is carried, the objective surface of the photographic lens 1 is covered with a lens barrier (not shown). When the user operates the power switch 6 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 1, the optical systems of the respective groups constituting the zoom lens are arranged at, for example, a wide-angle end (short focal end), and by operating the zoom switch 10, When the arrangement of the group optical system is changed, the zooming operation to the telephoto end (long focal end) can be performed via the intermediate focal length. It is desirable that the optical system of the optical viewfinder 2 is also scaled in conjunction with the change in the angle of view of the photographing lens 1.

In many cases, focusing is performed by half-pressing the shutter button 4. The focusing in the zoom lens according to the present invention (the zoom lens defined in claims 1 to 8 or shown in the first to fourth embodiments described above) is one of a plurality of optical systems constituting the zoom lens. This can be done by moving the group of parts (for example, the fourth lens group G4) or by moving the light receiving element. When the shutter button 4 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 15 is displayed on the liquid crystal monitor 7 or transmitted to the outside via the communication card 16 or the like, the operation button 8 is operated in a predetermined manner. The semiconductor memory 15 and the communication card 16 are used by being loaded into dedicated or general-purpose slots such as the memory card slot 9 and the communication card slot.

  As described above, the above-mentioned digital camera (imaging device) or information device has a sufficiently wide half angle of view of 42 degrees or more as shown in the first to fourth embodiments. Although it has a wide angle of view, the F number at the short focal end is 2.0 or less, the F number at the long focal end is about 3.0, and it is configured by using a small number of zoom lenses of about 12-13. The taking lens 1 can be used as an imaging optical system. Therefore, a small-sized digital camera (imaging) having a zooming area that can sufficiently cover a normal photographing area with high image quality using a light receiving element having 10 to 20 million pixels or more. Device) or a portable information terminal device can be realized.

G1 first lens group (positive)
L11 First lens L12 Second lens G2 Second lens group (negative)
L21 First lens L22 Second lens L23 Third lens L24 Fourth lens G3 Third lens group (positive)
L31 1st lens L32 2nd lens L33 3rd lens L34 4th lens L35 5th lens L36 6th lens G4 4th lens group (positive)
L41 1st lens AD Aperture stop FM Parallel plate such as filter 1 Shooting lens 2 Optical viewfinder 3 Strobe (flashlight)
4 Shutter button 5 Camera body 6 Power switch 7 LCD monitor 8 Operation button 9 Memory card slot 10 Zoom switch 11 Central processing unit (CPU)
DESCRIPTION OF SYMBOLS 12 Image processing apparatus 13 Light receiving element 14 Signal processing apparatus 15 Semiconductor memory 16 Communication card etc.

JP 2010-139705 A JP 2009-223008 A JP 2000-347102 A

Claims (10)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. When zooming from the short focal end to the long focal end, the first lens group moves so as to be convex toward the image side, the second lens group moves toward the image side, and the third lens group In a zoom lens that moves to the object side and moves the fourth lens group, an aperture stop is disposed between the second lens group and the third lens group, and the first lens group is negative in order from the object side. The second lens group is composed of a negative lens L21, a negative lens L22, a negative lens L23, and a positive lens L24 in order from the object side, and satisfies the following conditional expression (1). A featured zoom lens.
0.5 <| f2 / ft | <0.7 (1)
Here, f2 is the focal length of the second lens group, and ft is the focal length of the entire system at the long focal end. 2. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
3.0 <f1 / ft <4.0 (2)
Here, f1 is the focal length of the first lens group, and ft is the focal length of the entire system at the long focal end. The zoom lens according to claim 1 or 2, wherein the following conditional expression is satisfied.
0.3 <D1 / D2 <0.5 (3)
However, D1 is the thickness on the optical axis of the first lens group, and D2 is the thickness on the optical axis of the second lens group. 4. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. 5.
0.4 <f2_1 / f2_2 <0.8 (4)
Here, f2_1 is the focal length of the negative lens L21 of the second lens group, and f2_2 is the focal length of the negative lens L22 of the second lens group. 5. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. 6.
0.3 <Da / D2 <0.5 (5)
However, Da is an air space between the negative lens L22 and the negative lens L23 of the second lens group, and D2 is a thickness on the optical axis of the second lens group.   The zoom lens according to any one of claims 1 to 5, wherein the negative lens L22 of the second lens group is an aspherical lens. The zoom lens according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.
0.7 <H212 / R212 <0.9 (6)
Where H212 is the effective ray height of the negative lens L21 of the second lens group, and R212 is the radius of curvature of the negative lens L21 of the second lens group. 8. The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.15 <TLs3_w / TL2s_w <0.40 (7)
However, TLs3_w is the distance between the aperture stop and the third lens group at the short focal end, and TL2s_w is the distance between the second lens group and the aperture stop at the short focal end.   A camera comprising the zoom lens according to any one of claims 1 to 8 as a photographing optical system.   9. A portable information terminal device comprising the zoom lens according to claim 1 as a photographing optical system of a camera function unit.

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