JP2009069794A - Image-forming optical system and electronic imaging apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-forming optical system etc. which is made compact and low-profile. <P>SOLUTION: The image-forming optical system has a positive lens group, a negative lens group and a diaphragm, wherein the negative lens group is disposed at a position nearer the image side than the diaphragm, the negative lens group has a cemented lens formed by joining a plurality of lenses, and wherein when a straight line expressed by θgF=α×νd+β (wherein α=-0.00163) is set in an orthogonal coordinate system having a horizontal axis νd and a vertical axis θgF, θfF and νd of at least one lens composing the negative lens group are contained in both an area determined by the straight lines that are respectively the lower limit and upper limit of a range expressed by conditional expression (1): 0.3000<β<0.6650 and an area determined by conditional expression (2): 29<νd<120. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging optical system used for an imaging module, and an electronic imaging apparatus having the imaging optical system.

In recent years, digital cameras have become widespread as next-generation cameras that replace silver salt 35 mm film cameras. Recently, digital cameras have become increasingly smaller and thinner.
In addition, camera functions have been mounted on mobile phones that are becoming popular at the same time (hereinafter, camera functions are referred to as “imaging modules”). In order to mount an imaging module on a mobile phone, the zoom lens must be smaller and thinner than a digital camera. However, zoom lenses that are small enough to be installed in mobile phones are not well known.

Conventionally, the following two means A and B can be considered as representative means for reducing the size and thickness of a zoom lens. That is,
A. A retractable lens barrel is used to house the optical system in the thickness (depth) direction of the housing. The collapsible lens barrel is a lens barrel having a structure in which an optical system protrudes from the camera case during photographing and is housed in the camera case when carried.
B. A bending optical system is employed to accommodate the optical system in the width direction or height direction of the casing. This bending optical system is an optical system configured to bend the optical path (optical axis) of the optical system with a reflective optical element such as a mirror or a prism.

  The conventional example using the means A is described in, for example, the following Patent Document 1, and the conventional example using the means B is, for example, described in the following Patent Document 2. .

  In order to reduce the size and thickness of the zoom lens, correction of chromatic aberration is an important issue. As a solution to this problem, transparent media having effective dispersion characteristics or partial dispersion characteristics not found in conventional glass are known, for example, in Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6 below. ing.

  Furthermore, in an electronic imaging apparatus using an electronic imaging element, flare due to chromatic aberration of h-rays (404.66 nm) is likely to occur. For this reason, for example, the following Patent Document 7 is known as an explanation of the importance of correcting the chromatic aberration of the h-line.

  Further, there is no optical medium having a desired partial dispersion characteristic that can correct chromatic aberration in the vicinity of 400 nm. Therefore, for example, the following Patent Document 8 is known as an object of capturing an image by intentionally lowering the transmittance of 400 nm and adjusting the color reproduction using the image processing function of the image capturing apparatus after the image capturing.

  In addition, since the optical material itself is unsatisfactory in partial dispersion characteristics on the short wavelength side, color flare that could not be corrected by the optical system itself is corrected by image processing. Are known.

JP 2002-365545 A JP 2003-43354 A Japanese Patent Laid-Open No. 2005-181392 JP 2006-145823 A JP 2003-241091 A JP 2006-003544 A JP 2001-208964 A JP 2001-021805 A JP 2001-145117 A JP 2001-268583 A

  However, in the configuration using the means A described in Patent Document 1, the number of lenses constituting the optical system or the number of moving lens groups is still large, and it is difficult to reduce the size and thickness of the housing.

  The configuration using the means B described in Patent Document 2 is easier to make the housing thinner than the case using the means A, but the amount of movement of the movable lens group at the time of zooming, The number of lenses constituting the system tends to increase. Therefore, it is not suitable for miniaturization in volume.

  Further, the optical media described in Patent Documents 3 and 4 are highly dispersed and have a special partial dispersion ratio compared to ordinary optical glass. Considering each example in view of this, application to the optical system is not necessarily the optimum application. As a result, the number of sheets has increased in the end, and this has not led to the miniaturization of the optical system. The optical medium described in Patent Document 5 has a low dispersion and a special partial dispersion ratio as compared with normal optical glass, but correction of chromatic aberration is sufficient because of the low specialness (abnormal dispersion) of the partial dispersion ratio. is not. Patent Document 6 discloses an optical medium having a special partial dispersion ratio in low dispersion and high dispersion.

  Further, Patent Documents 6, 7, 8, 9, and 10 do not describe specific effective means for removing color flare in the optical system.

  The present invention has been made in view of the above-described conventional problems, and it is possible to obtain an imaging optical system in which various aberrations centering on chromatic aberration are favorably corrected, as well as reduction in size and thickness of the optical system. An object of the imaging device is to sharpen an image and prevent occurrence of color blur.

In order to achieve the above object, an optical system according to the present invention is an imaging optical system having a positive lens group, a negative lens group, and a diaphragm. In an orthogonal coordinate system with the axis νd and the vertical axis θgF,
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (1) and the straight line when the upper limit is set, and the following conditional expression (2) It is characterized in that θgF and νd of at least one lens LA constituting the negative lens group are included in both of the fixed region and the fixed region.
0.3000 <β <0.6650 (1)
29 <νd <120 (2)
Here, θgF is a partial dispersion ratio (ng−nF) / (nF−nC), νd is an Abbe number (nd−1) / (nF−nC), nd, nC, nF, and ng are d line and C line, respectively. , F-line, and g-line refractive indexes.

Further, according to a preferred aspect of the present invention, in an orthogonal coordinate system having a horizontal axis νd and a vertical axis θhg different from the orthogonal coordinate,
θhg = αhg × νd + βhg (where αhg = −0.00225)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (3) and the straight line when the upper limit is set, and the following conditional expression (2) It is characterized in that θhg and νd of at least one of the lenses LA constituting the negative lens group are included in both the fixed region and the region.
0.2500 <βhg <0.6220 (3)
29 <νd <120 (2)
Here, .theta.hg is the partial dispersion ratio (nh-ng) / (nF-nC), and nh is the refractive index of the h-line.

  According to a preferred aspect of the present invention, the lens LA is preferably a lens constituting a cemented lens.

  According to a preferred aspect of the present invention, when a lens having a negative paraxial focal length is a negative lens, the lens LA is preferably a negative lens.

According to a preferred aspect of the present invention, when a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is joined is a positive lens and satisfies the following conditions: To do.
−0.40 ≦ θgF (LA) −θgF (LB) ≦ −0.04 (4)
Here, θgF (LA) is the partial dispersion ratio (ng−nF) / (nF−nC) of the lens LA, and θgF (LB) is the partial dispersion ratio (ng−nF) / of the mating lens LB to be joined. (NF-nC).

According to a preferred aspect of the present invention, when a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is joined is a positive lens and satisfies the following conditions: To do.
−0.50 ≦ θhg (LA) −θhg (LB) ≦ −0.06 (5)
Here, .theta.hg (LA) is the partial dispersion ratio (nh-ng) / (nF-nC) of the lens LA, and .theta.hg (LB) is the partial dispersion ratio (nh-ng) / of the mating lens LB to be joined. (NF-nC).

According to a preferred aspect of the present invention, when a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is joined is a positive lens and satisfies the following conditions: To do.
−10 ≦ νd (LA) −νd (LB) (6)
Here, νd (LA) is the Abbe number (nd-1) / (nF-nC) of the lens LA, and νd (LB) is the Abbe number (nd-1) / (nF) of the mating lens LB to be joined. -NC).

  According to a preferred aspect of the present invention, the imaging optical system is a zoom lens, and the relative distance between the lens groups on the optical axis changes during zooming.

In addition, an electronic imaging device of the present invention is obtained by capturing an image formed through the imaging optical system with any one of the above-described imaging optical system of the present invention, an electronic imaging device, and the electronic imaging device. Image processing means for processing the obtained image data and outputting it as image data in which the shape of the image is changed. The imaging optical system is a zoom lens, and the zoom lens is focused on an object point at infinity. Sometimes the following condition is satisfied.
0.7 <y ₀₇ / (fw · tan ω _07w ) <0.97 (9)
Here, y ₀₇ is y ₀₇ = 0.7 · y, where y ₁₀ is the distance (maximum image height) from the center to the farthest point in the effective imaging plane (in the plane where imaging is possible) of the electronic imaging device. represented as _10, omega _07w angle relative to the central from the optical axis direction of an object point corresponding to an image point formed at a position of y ₀₇ on the imaging surface at the wide angle end, fw is the entire system at the wide-angle end of said zoom lens The focal length.

  According to the present invention, it is possible to obtain an imaging optical system in which the optical system is reduced in size and thickness, and various aberrations centered on chromatic aberration are favorably corrected. In addition, by using such an imaging optical system in an electronic imaging device, it is possible to sharpen an image and prevent color blurring.

  Prior to the description of the examples, the effects of the imaging optical system of the present embodiment will be described. A lens having a positive paraxial focal length is defined as a positive lens, and a lens having a negative paraxial focal length is defined as a negative lens.

  In the imaging optical system of the present embodiment, a lens LA made of a medium having an Abbe number appropriate for the negative lens group on the image side from the stop and having a large anomalous partial dispersion ratio is used. For this reason, particularly in a zoom lens, particularly in a zoom lens, it is possible to easily suppress a change in on-axis and lateral chromatic aberration during zooming. In addition, even if the lens configuration is small and thin, it is possible to sufficiently suppress the occurrence of color blur over the entire zoom range.

  Further, the negative lens group on the image side than the stop tends to be thick, but in the imaging optical system of the present embodiment, the negative lens group on the image side than the stop can be made thinner. Therefore, the thickness in the optical axis direction when the lens barrel is retracted can be reduced.

In the imaging optical system of the present embodiment, in the orthogonal coordinate system in which the horizontal axis is νd and the vertical axis is θgF,
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (1) and the straight line when the upper limit is set, and the following conditional expression (2) Both the fixed region and θgF and νd of at least one lens LA constituting the negative lens group are included.
0.3000 <β <0.6650 (1)
29 <νd <120 (2)
Here, θgF is the partial dispersion ratio (ng−nF) / (nF−nC), νd is the Abbe number (nd−1) / (nF−nC), nd, nC, nF, and ng are the d line and C line, respectively. , F-line, and g-line refractive indexes.

The case where a glass material exceeding the upper limit value of conditional expression (1) is used will be described. When this glass material is used for a positive lens, correction of axial and magnification chromatic aberration due to the secondary spectrum, that is, g-axis and magnification chromatic aberration when the achromaticity is applied to the F-line and C-line, becomes insufficient. Therefore, it is difficult to ensure sharpness in an image obtained by imaging.
In addition, when this glass material is used for a negative lens, the axial and lateral chromatic aberration due to the secondary spectrum, that is, the axial and lateral chromatic aberration correction of the g-line when achromatized by the F-line and C-line are reversed. Not enough. Therefore, it is difficult to ensure sharpness in the image obtained by imaging.

The case where a glass material lower than the lower limit value of conditional expression (1) is used will be described. When this glass material is used for a positive lens, the axial and lateral chromatic aberration due to the secondary spectrum in the same direction as the case of the negative lens using a glass material exceeding the upper limit described above, that is, achromatic with F-line and C-line The correction of the chromatic aberration of magnification and the chromatic aberration on the g-line is not sufficient. Therefore, it is difficult to ensure sharpness in the image obtained by imaging.
In addition, when this glass material is used for a negative lens, axial and lateral chromatic aberration due to the secondary spectrum in the same direction as in the case of a positive lens using a glass material exceeding the upper limit described above, that is, F-line and C-line Correction of chromatic aberration on the axis of the g-line and magnification when achromatic is performed becomes insufficient. Therefore, it is difficult to ensure sharpness in the image obtained by imaging.

A case where a glass material exceeding the upper limit value of conditional expression (2) is used will be described. When this glass material is used for a positive lens, it is difficult to erase the F line and C line.
Further, when this glass material is used for a negative lens, the effect of correcting Seidel's five aberrations is reduced even if the F-line and C-line can be achromatic.

A case where a glass material lower than the lower limit value of conditional expression (2) is used will be described. When this glass material is used for a positive lens, the effect of correcting Seidel's five aberrations is reduced even if the F-line and C-line can be achromatic.
In addition, when this glass material is used for a negative lens, it is difficult to erase the F line and the C line.

It is more preferable that the following conditional expression (1 ′) is satisfied instead of conditional expression (1).
0.3000 <β <0.6300 (1 ′)
Furthermore, it is more preferable that the following conditional expression (1 ″) is satisfied instead of conditional expression (1).
0.5000 <β <0.6250 (1 ″)

It is more preferable that the following conditional expression (2 ′) is satisfied instead of conditional expression (2).
29 <νd <85 (2 ′)
Furthermore, it is more preferable that the following conditional expression (2 ″) is satisfied instead of conditional expression (2).
29 <νd <72 (2 ″)

Further, in the imaging optical system of the present embodiment, the orthogonal coordinate having the horizontal axis νd and the vertical axis θhg is different from the orthogonal coordinate (orthogonal coordinate having the horizontal axis νd and the vertical axis θgF). In the coordinate system
θhg = αhg × νd + βhg (where αhg = −0.00225)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (3) and the straight line when the upper limit is set, and the following conditional expression (2) Both the fixed region and θhg and νd of at least one lens LA constituting the negative lens group are included.
0.2500 <βhg <0.6220 (3)
29 <νd <120 (2)
Here, .theta.hg is the partial dispersion ratio (nh-ng) / (nF-nC), and nh is the refractive index of the h-line.

The case where a glass material exceeding the upper limit value of conditional expression (3) is used will be described. When this glass material is used for a positive lens, axial and lateral chromatic aberration due to the secondary spectrum, that is, correction of axial and lateral chromatic aberration of the h-line when achromatization is performed with the F-line and the C-line are not sufficient. For this reason, purple color flare and color blur are likely to occur in an image obtained by imaging.
In addition, when this glass material is used for a negative lens, the axial and lateral chromatic aberration due to the secondary spectrum, that is, the axial and lateral chromatic aberration correction of the h-line when achromatic with the F-line and the C-line are erased in the opposite direction. Not enough. Therefore, purple color flare and color blur are likely to occur in an image obtained by imaging.

A case where a glass material lower than the lower limit value of conditional expression (3) is used will be described. When this glass material is used for a positive lens, the axial and lateral chromatic aberration due to the secondary spectrum in the same direction as the case of the negative lens using a glass material exceeding the upper limit described above, that is, achromatic with F-line and C-line The correction of chromatic aberration of magnification and chromatic aberration on the axis of the h line is not sufficient. Therefore, purple color flare and color blur are likely to occur in an image obtained by imaging.
In addition, when this glass material is used for a negative lens, axial and lateral chromatic aberration due to the secondary spectrum in the same direction as in the case of a positive lens using a glass material exceeding the upper limit described above, that is, F-line and C-line On the axis of the h line when the color is erased, the chromatic aberration of magnification is not sufficiently corrected. For this reason, purple color flare and color blur are likely to occur in the captured image.

It is more preferable that the following conditional expression (3 ′) is satisfied instead of conditional expression (3).
0.2500 <βhg <0.5730 (3 ′)
Furthermore, it is more preferable that the following conditional expression (3 ″) is satisfied instead of conditional expression (3).
0.4000 <βhg <0.5650 (3 ″)

  The lens LA is preferably a lens constituting a cemented lens. That is, it is preferable that a lens LB which is another lens element is bonded to the lens LA.

  Incidentally, the lens LA is preferably a negative lens. This lens LA is provided in a negative lens group on the image side of the stop. When the lens LA is a negative lens, it is easy to cancel axial chromatic aberration and lateral chromatic aberration generated by the negative lens group itself. As a result, it becomes easy to correct chromatic aberration occurring in the entire optical system.

The lens LA is cemented with another lens to constitute a cemented lens. When this other lens is the lens LB, the lens LB is a positive lens and preferably satisfies the following conditional expression (4).
−0.40 ≦ θgF (LA) −θgF (LB) ≦ −0.04 (4)
Here, θgF (LA) and θgF (LB) are partial dispersion ratios (ng−nF) / (nF−nC) of the lenses LA and LB, respectively.

  In this case, since a negative lens (lens LA) and a positive lens (lens LB) are combined, chromatic aberration can be corrected satisfactorily. In particular, when the above condition is satisfied with this combination, the effect of correcting chromatic aberration due to the secondary spectrum is increased. As a result, sharpness increases in an image obtained by imaging.

It is more desirable to satisfy (4 ′) instead of the conditional expression (4).
−0.40 ≦ θgF (LA) −θgF (LB) ≦ −0.06 (4 ′)
Furthermore, it is best to satisfy (4 ″) instead of the conditional expression (4).
−0.40 ≦ θgF (LA) −θgF (LB) ≦ −0.08 (4 ″)

The lens LB is a positive lens, and preferably satisfies the following conditional expression (5).
−0.50 ≦ θhg (LA) −θhg (LB) ≦ −0.06 (5)
Here, θhg (LA) and θhg (LB) are partial dispersion ratios (nh−ng) / (nF−nC) of the lenses LA and LB, respectively.

  In this case, since a negative lens (lens LA) and a positive lens (lens LB) are combined, chromatic aberration can be corrected satisfactorily. In particular, when the above condition is satisfied with this combination, color flare and color blur can be reduced in an image obtained by imaging.

It is more desirable to satisfy (5 ′) instead of the conditional expression (5).
−0.50 ≦ θhg (LA) −θhg (LB) ≦ −0.08 (5 ′)
Furthermore, it is best to satisfy 5 ″) instead of the conditional expression (5).
−0.50 ≦ θhg (LA) −θhg (LB) ≦ −0.10 (5 ″)

The lens LB is a positive lens, and preferably satisfies the following conditional expression (6).
−10 ≦ νd (LA) −νd (LB) (6)
Here, νd (LA) and νd (LB) are the Abbe numbers (nd-1) / (nF-nC) of the lenses LA and LB, respectively.

  In this case, since a negative lens (lens LA) and a positive lens (lens LB) are combined, chromatic aberration can be corrected satisfactorily. In particular, when the above condition is satisfied with this combination, the C-line and F-line among the longitudinal chromatic aberration and the lateral chromatic aberration are easily erased.

It is more desirable to satisfy (6 ′) instead of the conditional expression (6).
5 ≦ νd (LA) −νd (LB) (6 ′)
Furthermore, it is best to satisfy (6 ″) instead of the conditional expression (6).
20 ≦ νd (LA) −νd (LB) (6 ″)

  When the cemented lens is composed of three or more lenses, the negative lens having the smallest θgF value among the negative lenses is defined as the lens LA, and the positive lens having the largest θgF value among the positive lenses is defined as the lens LB. And

  Here, the glass material means a lens material such as glass or resin. In addition, a lens appropriately selected from these glass materials is used for the cemented lens.

  The cemented lens includes a first lens and a second lens having a thin optical axis center thickness. The first lens is conditional expressions (1) and (2), or (3) and (2). Is preferably satisfied. By doing so, it is possible to expect further improvement of the correction effect of each aberration and further thinning of the lens group.

  The cemented lens is preferably a compound lens. The compound lens can be realized by closely curing a resin as a second lens on the surface of the first lens. Manufacturing accuracy can be improved by using a cemented lens as a compound lens. A compound lens manufacturing method includes molding. In the molding, there is a method in which a second lens material (for example, an energy curable transparent resin) is brought into contact with the first lens, and the second lens material is directly adhered to the first lens. This method is extremely effective for thinning the lens element.

  When a cemented lens is used as a compound lens, glass may be adhered and cured as a first lens on the second lens surface. Glass is more advantageous than resin in terms of resistance such as light resistance and chemical resistance. In this case, as the characteristics of the second lens material, it is necessary that the melting point and the transition point are lower than those of the first lens material. A compound lens manufacturing method includes molding. In molding, there is a method in which the second lens material is brought into contact with the first lens, and the second lens material is brought into direct contact with the first lens. This method is extremely effective for thinning the lens element. The first lens may be subjected to surface treatment such as coating in advance.

  An example of the energy curable transparent resin is an ultraviolet curable resin. In addition, whether the first lens is a resin or glass, the lens on the side serving as the substrate may be subjected to a surface treatment such as coating in advance. When the second lens is thinner, the first lens may be in close contact with the second lens. The first lens may be an inorganic material such as glass, but the second lens to be joined is a resin, and considering the stability of optical performance against environmental changes, the resin is basically the same as the second lens. It is more preferable to use the material.

  In addition, it is preferable to arrange a prism in the imaging optical system. This prism is used to bend the optical path of the optical system. In particular, when the imaging optical system is a zoom lens, the depth dimension of the optical system can be reduced (the entire length can be reduced). This prism is preferably arranged in the first positive lens group or negative lens group particularly from the object side.

By the way, suppose that an object at infinity is imaged by an optical system without distortion. In this case, since the image formed has no distortion,
f = y / tan ω (7)
Is established.
Here, y is the height of the image point from the optical axis, f is the focal length of the imaging system, and ω is the angle with respect to the optical axis in the object direction corresponding to the image point connected from the center on the imaging surface to the y position. It is.

On the other hand, if the optical system has barrel distortion,
f> y / tan ω (8)
It becomes. That is, if f and y are constant values, ω is a large value.

  Therefore, it is preferable to use an optical system that intentionally has a large barrel distortion, particularly at a focal length near the wide-angle end, for the electronic imaging device. In this case, it is possible to achieve a wider angle of view of the optical system as much as it is not necessary to correct distortion.

  However, the image of the object is formed on the electronic image pickup device in a state having barrel-shaped distortion. Therefore, in the electronic imaging device, image data obtained by the electronic imaging element is processed by image processing. In this processing, the image data (image shape) is changed so as to correct the barrel distortion.

  In this way, the finally obtained image data is image data having a shape substantially similar to the object. Therefore, an object image may be output to a CRT or printer based on the image data.

Therefore, it is preferable to use an imaging optical system that satisfies the following conditional expression (9) when focusing on an object point at infinity.
0.7 <y ₀₇ / (fw · tan ω _07w ) <0.97 (9)
Here, y ₀₇ is y ₀₇ = 0.7 · y ₁₀ when the distance to the point farthest from the center (maximum image height) was y ₁₀ at effective imaging plane of the electronic imaging device (imaging possible plane) Ω _07w is the angle with respect to the optical axis in the object direction corresponding to the image point connecting from the center on the imaging surface at the wide angle end to the position of y ₀₇ , and fw is the focal length of the entire system at the wide angle end of the zoom lens is there.

  Conditional expression (9) defines the degree of barrel distortion at the zoom wide-angle end. If conditional expression (9) is satisfied, it becomes possible to capture information with a wide angle of view without enlarging the optical system. Note that an image distorted in a barrel shape is photoelectrically converted by an image sensor to become image data distorted in a barrel shape.

  The image data distorted into a barrel shape is electrically processed by an image processing means, which is a signal processing system of an electronic imaging device, corresponding to a change in the shape of the image. In this way, even if the image data finally output from the image processing means is reproduced on the display device, the distortion is corrected and an image substantially similar to the subject shape is obtained.

  Here, when the value exceeds the upper limit value of conditional expression (9) and takes a value close to 1, an image in which distortion is optically corrected is obtained. Therefore, the correction performed by the image processing means can be small. However, it is difficult to widen the angle of view of the optical system while maintaining the miniaturization of the optical system.

  On the other hand, below the lower limit value of conditional expression (9), when image distortion due to distortion of the optical system is corrected by the image processing means, the stretching ratio in the radial direction of the peripheral portion of the angle of view becomes too high. As a result, in the image obtained by imaging, the sharpness degradation at the periphery of the image becomes conspicuous.

  Thus, by satisfying conditional expression (9), it is possible to reduce the size and widen the angle of the optical system (make the vertical angle of view of distortion more than 38 °).

It is more preferable that the following conditional expression (9 ′) is satisfied instead of conditional expression (9).
0.7 <y ₀₇ / (fw · tan ω _07w ) <0.95 (9 ′)
Furthermore, it is more preferable that the following conditional expression (9 ″) is satisfied instead of conditional expression (9).
0.75 <y ₀₇ / (fw · tan ω _07w ) <0.92 (9 ″)

In the imaging optical system of the present embodiment, θgF and νd of the lens LB are in an orthogonal coordinate system in which the horizontal axis is νd and the vertical axis is θgF.
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the area defined by the straight line when it is the lower limit value and the straight line when it is the upper limit value of the range of the following conditional expression (10), and the following conditional expression (11) It should be included in both the fixed area and the fixed area.
0.6700 <β <0.9000 (10)
3 <νd <30 (11)

  In this case, it is particularly preferable to use a negative lens that satisfies the conditional expressions (1) and (2), and a positive lens that satisfies the conditional expressions (10) and (11). As a result, the correction of axial / magnification chromatic aberration (on-axis / magnification of F-line and C-line) and secondary spectrum (g-line residual chromatic aberration when achromatized by F-line and C-line) are obtained. Correction can be performed effectively.

Alternatively, θgF and νd of the lens LB are in an orthogonal coordinate system in which the horizontal axis is νd and the vertical axis is θgF.
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the region defined by the straight line when the range is the lower limit of the range of the following conditional expression (12) and the straight line when the upper limit is set, and the following conditional expression (13) It should be included in both the fixed area and the fixed area.
0.6300 <β <0.9000 (12)
30 <νd <120 (13)

  In this case, it is particularly preferable to use a negative lens that satisfies the conditional expressions (1) and (2) and a positive lens that satisfies the conditional expressions (12) and (13). As a result, it is possible to effectively correct the secondary spectrum (the residual chromatic aberration of the g line when the achromaticity is applied to the F line and the C line).

Alternatively, θgF and νd of the lens LB are in an orthogonal coordinate system in which the horizontal axis is νd and the vertical axis is θgF.
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit value and the straight line when the upper limit value is in the range of the following conditional expression (14), and the following conditional expression (15) It should be included in both the fixed area and the fixed area.
0.4000 <β <0.6700 (14)
3 <νd <30 (15)

  In this case, it is particularly preferable to use a negative lens that satisfies the conditional expressions (1) and (2) and a positive lens that satisfies the conditional expressions (14) and (15). As a result, the correction of axial / magnification chromatic aberration (on-axis / magnification of F-line and C-line) and secondary spectrum (g-line residual chromatic aberration when achromatized by F-line and C-line) are obtained. Correction can be performed effectively.

The lens LA should satisfy the following conditional expression (16).
1.35 <nd <2.20 (16)
Here, nd is the refractive index of the medium of the lens LA.
If the condition (16) is satisfied, spherical aberration correction and astigmatism correction can be performed satisfactorily.

It is more preferable that the following conditional expression (16 ′) is satisfied instead of conditional expression (16).
1.40 <nd <2.15 (16 ′)
Furthermore, it is more preferable that the following conditional expression (16 ″) is satisfied instead of conditional expression (16).
1.45 <nd <2.10 (16 ")

  In addition, in the case where the most object side of the imaging optical system (particularly the zoom lens) is a positive lens group or a negative lens group, the above cemented lens is the first negative lens group from the stop toward the image side. It is preferable to use it.

  The imaging optical system is a zoom lens, and it is preferable that the relative distance on the optical axis of each lens group changes during zooming. The cemented lens is preferably applied to such an imaging optical system (zoom lens).

Next, the imaging optical system of this embodiment will be described.
As the imaging optical system of the present embodiment, there are a four-group optical system and a five-group optical system. The refractive power arrangement in the imaging optical system of the four-group configuration imaging optical system is as follows.
Negative / Positive / (S) / Negative / Positive / Negative / (S) / Positive / Negative / Positive / Negative (S) / Positive / Positive / Negative (However, this is not a specific example)
In addition, the refractive power arrangement in the five-group imaging optical system is one of the following.
Positive, negative, (S), positive, negative, positive positive, negative, (S), positive, positive, negative (S) indicates the aperture stop. The aperture stop may or may not be independent of the lens group.

  The imaging optical system of the present embodiment has negative, positive, and positive lens groups in order from the object side, regardless of the number of groups. Therefore, the negative, positive, and positive configurations are common. Furthermore, when focusing on the aperture stop, (1) a configuration including two positive lens groups on the image side of the aperture stop, and (2) a negative lens group and a positive lens group on the object side of the aperture stop. It is divided into the composition equipped with. This is also common in that a negative lens group is provided on the object side of the aperture stop. Therefore, it can be said that the imaging optical system of the present embodiment has a basic configuration of negative / (S) / positive / positive or negative / positive / (S) / positive.

  In this basic configuration, the following lens LA is used for the negative lens group disposed on the object side of the stop.

  If another lens group is provided on the image side of the aperture stop, the other lens group is disposed between the two positive lens groups or between the stop and the positive lens group. Can be considered.

  The imaging optical system of the present embodiment has a four-group configuration based on a negative / positive / positive three-group configuration, that is, a common negative / positive / negative / positive configuration, or a negative / positive / positive configuration.・ The negative structure is shared. Further, the imaging optical system having the five-group configuration can be regarded as an optical system obtained by modifying the imaging optical system having the four-group configuration. For example, in a five-group imaging optical system, a positive lens group is added closest to the object side, so that the refractive power arrangement is positive / negative / positive / negative / positive or positive / negative / positive / positive / negative. The imaging optical system has a group configuration.

  The four-group imaging optical system has three groups (positive / negative / positive) on the object side and a final group (positive). Then, the imaging optical system having the five-group configuration can be regarded as a positive or negative lens group disposed between the three groups on the object side and the final group. Alternatively, the imaging optical system having a five-group configuration can be regarded as having a positive or negative lens group disposed further behind the final group.

  Further, as described above, regarding the four-group configuration of negative / positive / negative / positive /, by adding a positive lens group closest to the object side, as a result, the refractive power arrangement is positive / negative / positive / negative. -The imaging optical system has a positive 5-group configuration. However, it is preferable to consider the above-mentioned positive / negative / positive / positive refractive power arrangement as a basic configuration in the five-group configuration of positive / negative / positive / negative / positive refractive power arrangement.

  When the common configuration is negative / positive / negative / positive, a lens LA that satisfies the conditional expressions (1) and (2) is used for the negative lens group located on the image side of the aperture stop. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2). It is particularly preferable that the negative lens group has a cemented lens formed by cementing a plurality of lenses, and the lens LA is used for the cemented lens.

  The first negative lens group, that is, the negative lens group closest to the object side has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens.

  The first negative lens group may further include another lens component. This other lens component is preferably arranged closer to the object side than the lens component having the cemented lens. The first negative lens group may include a prism. This prism is preferably arranged between two lens components.

  The first positive lens group has one lens component. Here, one lens component is composed of a cemented lens of a positive lens and a negative lens. Further, it is preferable that the most image side of the cemented lens is a negative lens.

  The first positive lens group may further include another lens component. This other lens component is preferably arranged closer to the object side than the lens component having the cemented lens. Note that the first positive lens group preferably has a negative lens closest to the image side.

  The second negative lens group has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. As described above, a lens LA that satisfies the conditional expressions (1) and (2) is used for this cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  It can be said that this second negative lens group corresponds to another lens group described in the basic configuration of positive / negative / positive / positive. Therefore, the second negative lens group can have a positive refractive power. As described above, if the optical system has a negative refractive power, the optical system can be easily miniaturized.

  The second positive lens group has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. Alternatively, this lens component may be a single lens.

  When the common configuration is negative, positive, positive, or negative, a lens LA that satisfies the conditional expressions (1) and (2) is used for the negative lens group located on the image side of the aperture stop. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2). It is particularly preferable that the negative lens group has a cemented lens formed by cementing a plurality of lenses, and the lens LA is used for the cemented lens.

  The first negative lens group, that is, the negative lens group closest to the object side has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens.

  The first negative lens group may further include another lens component. This other lens component is preferably arranged closer to the object side than the lens component having the cemented lens.

  The first positive lens group has one lens component. Here, one lens component is composed of a cemented lens of a positive lens and a negative lens. Further, it is preferable that the most image side of the cemented lens is a negative lens.

  The first positive lens group may further include another lens component. This other lens component is preferably arranged closer to the object side than the lens component having the cemented lens. Note that the first positive lens group preferably has a negative lens closest to the image side.

  The second positive lens group has one lens component. This lens component may be a single lens.

  The second negative lens group has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. As described above, a lens LA that satisfies the conditional expressions (1) and (2) is used for this cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  The second negative lens group may further include another lens component. This other lens component is preferably arranged closer to the image side than the lens component having the cemented lens.

In each imaging optical system described so far, when the most object-side lens group includes a prism, the position of the most object-side lens group is fixed during zooming from the wide-angle end to the telephoto end. It is. When the imaging optical system does not include a prism, the lens unit closest to the object moves monotonously to the image side during zooming from the wide-angle end to the telephoto end.
In each basic configuration, the first positive lens unit moves monotonously to the object side during zooming from the wide-angle end to the telephoto end.

  Then, it demonstrates for every group structure. First, an imaging optical system having a four-group configuration will be described. There are two types of four-group imaging optical systems. The first type imaging optical system includes, in order from the object side, a negative first lens group G1, an aperture stop, a positive second lens group G2, a negative third lens group G3, and a positive fourth lens group. It consists of four lens groups, G4.

  The negative first lens group G1 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. The cemented lens is preferably configured so that the negative lens and the positive lens are arranged in this order from the object side.

  The positive second lens group G2 has two lens components. Of the two lens components, one lens component is a positive lens component. The other lens component is composed of a cemented lens of a positive lens and a negative lens. Further, it is preferable that one lens component is located closer to the object side than the other lens component. The most image side of the positive second lens group G2 is preferably a negative lens.

  Here, one lens component is composed of one positive lens. This one lens component may be a positive single lens. Moreover, it is preferable that the cemented lens in the other lens component is configured in the order of a positive lens and a negative lens from the object side.

  Thus, the positive second lens group G2 has a lens component arranged in the order of a positive lens component (one lens component) and a lens component having the cemented lens (the other lens component). The most image side is a negative lens.

  Alternatively, it is preferable that one lens component has a biconvex shape and the other lens component has a meniscus shape that is convex toward the object side. One lens component is preferably located closer to the object side than the other lens component. The most image side of the cemented lens is a negative lens.

  The negative third lens group G3 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. The cemented lens is preferably configured so that the negative lens and the positive lens are arranged in this order from the object side.

  A lens LA that satisfies the conditional expressions (1) and (2) is used as the negative lens of the cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  Further, the lens LA satisfying the conditions (1) and (2) is used as the negative lens of the negative third lens group G3. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  As described above, the lens component in the negative third lens group G3 includes a cemented lens of a positive lens and a negative lens. A lens LA satisfying conditional expressions (1) and (2) is used as the negative lens of the cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  The positive fourth lens group G4 has one lens component. This lens component is composed of one positive lens. This lens component may be a positive single lens.

  The second type of imaging optical system is different in the position of the aperture stop compared to the first type of imaging optical system. That is, the second type of imaging optical system includes, in order from the object side, a negative first lens group G1, a positive second lens group G2, an aperture stop, a negative third lens group G3, and a positive fourth lens group. It consists of four lens groups, the lens group G4.

  The negative first lens group G1 has two lens components. Of the two lens components, one lens component is a negative lens component. The other lens component is composed of a cemented lens of a positive lens and a negative lens. Further, it is preferable that one lens component is located closer to the object side than the other lens component.

  Here, one lens component is composed of one negative lens. This one lens component may be a negative single lens. Moreover, it is preferable that the cemented lens in the other lens component is configured in the order of a positive lens and a negative lens from the object side.

  The negative first lens group G1 may include a prism. The prism is disposed between the two lens components. This prism is used to bend the optical path. One lens component may be bonded to the prism or integrated with the prism (so that one surface of the prism is a negative lens).

  The positive second lens group G2 has one positive lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. It is preferable that the cemented lens is configured in the order of the positive lens and the negative lens from the object side.

  The negative third lens group G3 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. The cemented lens is preferably configured so that the negative lens and the positive lens are arranged in this order from the object side.

  Further, as the negative lens of the negative third lens group G3, a lens LA that satisfies the conditional expressions (1) and (2) is used. The lens LA may be a lens that satisfies (1 ') or (1 ") instead of (1) and (2') or (2") instead of (2).

  As described above, the lens component in the negative third lens group G3 includes a cemented lens of a positive lens and a negative lens. A lens LA satisfying conditional expressions (1) and (2) is used as the negative lens of the cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  The positive fourth lens group G4 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. It is preferable that the cemented lens is configured in the order of the positive lens and the negative lens from the object side. Thus, it is preferable that the most image side of the cemented lens is a negative lens. The most image side of the positive fourth lens group G4 is preferably a negative lens. The cemented lens has a biconvex shape.

  Next, an imaging optical system having a five-group configuration will be described. The first type of imaging optical system includes, in order from the object side, a positive first lens group G1, a negative second lens group G2, an aperture stop, a positive third lens group G3, and a negative fourth lens group. G4 includes a positive lens group G5.

  The positive first lens group G1 has two lens components. Of the two lens components, one lens component is a negative lens component. The other lens component is a positive lens component. Further, it is preferable that one lens component is located closer to the object side than the other lens component.

  Here, one lens component is composed of one negative lens. This one lens component may be a negative single lens. The other lens component is composed of one positive lens. This one lens component may be a positive single lens.

  The positive first lens group G1 may further include a prism. The prism is disposed between the two lens components. This prism is used to bend the optical path. One lens component may be bonded to the prism or integrated with the prism (so that one surface of the prism is a negative lens).

  The negative second lens group G2 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. The cemented lens is preferably configured so that the negative lens and the positive lens are arranged in this order from the object side.

  The positive third lens group G3 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. It is preferable that the cemented lens is configured in the order of the positive lens and the negative lens from the object side. Thus, it is preferable that the most image side of the cemented lens is a negative lens. The most image side of the positive third lens group G3 is preferably a negative lens. The cemented lens has a biconvex shape.

  The negative fourth lens group G4 has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. The cemented lens is preferably configured so that the negative lens and the positive lens are arranged in this order from the object side.

  Further, the lens LA that satisfies the conditional expressions (1) and (2) is used as the negative lens of the negative fourth lens group G4. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  As described above, the lens component in the negative fourth lens group G4 includes a cemented lens of a positive lens and a negative lens. A lens LA satisfying conditional expressions (1) and (2) is used as the negative lens of the cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  The positive fifth lens group G5 has one lens component. This lens component is composed of one positive lens. This lens component may be a positive single lens.

  The second type of imaging optical system includes, in order from the object side, a positive first lens group G1, a negative second lens group G2, an aperture stop, a positive third lens group G3, and a positive fourth lens group. It consists of five lens groups, G4 and a negative fifth lens group G5.

  The positive first lens group G1 has two lens components. Of the two lens components, one lens component is a negative lens component. The other lens component is composed of a cemented lens of a positive lens and a negative lens. At this time, it is preferable that one lens component is positioned closer to the object side than the other lens component.

  Here, one lens component is composed of one negative lens. This one lens component may be a negative single lens. Further, it is preferable that the cemented lens in the other lens component is configured in the order of the negative lens and the positive lens from the object side.

  The positive first lens group G1 may further include a prism. The prism is disposed between the two lens components. This prism is used to bend the optical path. One lens component may be bonded to the prism or integrated with the prim (as if one surface of the prism is a negative lens).

  The negative second lens group G2 has two lens components. Of the two lens components, one lens component is a negative lens component. The other lens component is composed of a cemented lens of a positive lens and a negative lens. At this time, it is preferable that one lens component is positioned closer to the object side than the other lens component.

  Here, one lens component is composed of one negative lens. This one lens component may be a negative single lens. Further, it is preferable that the cemented lens in the other lens component is configured in the order of the negative lens and the positive lens from the object side.

  The positive third lens group G3 has two lens components. Of the two lens components, one lens component is a positive lens component. The other lens component is composed of a cemented lens of a positive lens and a negative lens. At this time, it is preferable that one lens component is positioned closer to the object side than the other lens component. One lens component may be omitted.

  Here, one lens component is composed of one positive lens. This one lens component may be a positive single lens. Moreover, it is preferable that the cemented lens in the other lens component is configured in the order of a positive lens and a negative lens from the object side.

  Of the two lens components, one of the lens components is preferably biconvex. Further, it is preferable that the most image side of the cemented lens is a negative lens. The most image side of the positive third lens group G3 is preferably a negative lens.

  The positive third lens group G3 has lens components arranged in the order of a positive lens component (one lens component) and a lens component having the cemented lens (the other lens component), and is the most image of the cemented lens. The side is preferably a negative lens.

  Alternatively, it is preferable that one lens component has a biconvex shape and the other lens component has a meniscus shape that is convex toward the object side. One lens component is preferably located closer to the object side than the other lens component. The most image side of the cemented lens is a negative lens.

  The positive fourth lens group G4 has one lens component. This lens component is composed of one positive lens. This lens component may be a positive single lens.

  The negative fifth lens group G5 has two lens components. One of the two lens components is composed of a cemented lens of a positive lens and a negative lens. The other lens component is a positive lens component. At this time, it is preferable that one lens component is positioned closer to the object side than the other lens component.

  Here, it is preferable that the cemented lens in one lens component is configured in the order of a positive lens and a negative lens from the object side. The other lens component is composed of one positive lens. This one lens component may be a positive single lens.

  Further, the lens LA that satisfies the conditions (1) and (2) is used as the negative lens of the negative fifth lens group G5. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  As described above, one of the lens components in the negative fifth lens group G5 is composed of a cemented lens of a positive lens and a negative lens. A lens LA satisfying conditional expressions (1) and (2) is used as the negative lens of the cemented lens. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  In the above description, an optical system having a four-group configuration in which the refractive power arrangement is negative / positive / negative / positive or negative / positive / positive / negative is exemplified as the imaging optical system. In this configuration, if a lens group having a positive refractive power is disposed closest to the object side, it is advantageous for increasing the magnification when a zoom lens is used. In that case, the second positive lens group when the positive lens is arranged on the object side moves only to the object side when zooming from the wide-angle end to the telephoto end.

  As described above, if the distortion generated in the imaging optical system is corrected by the image processing function of the electronic imaging apparatus, other aberrations can be corrected satisfactorily and at the same time, the angle of view can be further widened.

  In each of the imaging optical systems described so far, the lens satisfying conditional expressions (1) and (2) is preferably a negative lens as described above. The negative lens is preferably a lens that satisfies (1 ') or (1 ") instead of (1) and (2') or (2") instead of (2).

  Each imaging optical system described so far is a zoom lens. In such a zoom lens, it is preferable that the zoom lens is an optical system in which the relative distance between the lens groups changes during zooming.

  However, in each imaging optical system, when the most object-side lens group includes a prism, the position of the most object-side lens group is fixed when zooming from the wide-angle end to the telephoto end. preferable. If there is no lens group including a prism, the lens unit closest to the object moves monotonously along the optical axis toward the image side during zooming from the wide-angle end to the telephoto end.

  In addition, when the first lens group G1 is positive, the third lens group G3 moves monotonously toward the object side when the first lens group G1 is positive with zooming from the wide-angle end to the telephoto end.

  Note that the refractive power of one lens can be borne by a plurality of lenses. Therefore, in each lens group described above, for example, one lens can be replaced with two lenses. However, from the viewpoint of size reduction and thickness reduction, it is preferable that the number of lenses to be replaced is two. Although the replacement may be performed in each lens group, it is preferable that the number of lens groups to be replaced is small from the viewpoint of miniaturization and thinning.

When the lens LA is used as the cemented lens, the lens LA is cemented with the lens LB. At this time, the center thickness of the optical axis of the lens LA is preferably thinner than that of the lens LB. The optical axis center thickness t1 of the lens LA preferably satisfies the following conditional expression (17).
0.05 <t1 <1.5 (17)

  By satisfying the above conditions, it is possible to reduce the size of the optical system. Further, when the lens LA is obtained by molding, stable molding can be performed.

It is more preferable that the following conditional expression (17 ′) is satisfied instead of conditional expression (17).
0.05 <t1 <1.0 (17 ′)
Furthermore, it is more preferable that the following conditional expression (17 ″) is satisfied instead of conditional expression (17).
0.05 <t1 <0.75 (17 ")

  The lens LB is preferably an aspherical surface on at least one surface. Further, if the cemented surface is an aspherical surface, it is very effective in correcting chromatic aberration caused by differences in spherical aberration, coma aberration, and distortion due to wavelength.

  The imaging optical system of the present invention can achieve both downsizing and thinning of the imaging optical system by satisfying or having the conditional expressions and structural features described above individually. Good aberration correction can be realized. In addition, the imaging optical system of the present invention can be satisfied by combining the conditional expressions and structural features described above. In this case, the imaging optical system can be further reduced in size and thickness, or better aberration correction and a wider angle of view of the optical system can be achieved.

  In addition, the electronic imaging apparatus having the imaging optical system of the present invention is provided with such an imaging optical system, so that it is possible to sharpen the image and prevent color blur in the captured image.

  Next, a zoom lens according to embodiment 1 of the present invention will be described. FIGS. 1A and 1B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the first embodiment of the present invention when focusing on an object point at infinity. FIG. 1A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end. The numbers in r1, r2,... And the numbers in d1, d2,... Described in the lens cross-sectional views correspond to the numbers in the surface number column in the numerical data described later.

  FIG. 2 is a diagram illustrating spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) when the zoom lens according to Example 1 is focused on an object point at infinity. a) shows the wide-angle end, (b) shows the intermediate focal length state, and (c) shows the state at the telephoto end. FIY represents the image height. The symbols in the aberration diagrams are the same in the examples described later.

  As shown in FIG. 1, the zoom lens according to the first exemplary embodiment includes, in order from the object side, a first lens group G1, an aperture stop S, a second lens group G2, a third lens group G3, and a fourth lens group. G4. In all the following examples, in the lens cross-sectional views, LPF is a low-pass filter, CG is a cover glass, and I is an image pickup surface of an electronic image pickup element.

  The first lens group G1 includes a cemented lens of a negative biconcave lens L1 and a positive meniscus lens L2 having a convex surface directed toward the object side, and has a negative refracting power as a whole.

  The second lens group G2 includes a positive biconvex lens L3, and a cemented lens of a positive biconvex lens L4 and a negative biconcave lens L5, and has a positive refractive power as a whole.

  The third lens group G3 includes a cemented lens which is composed of a negative meniscus lens L6 having a convex surface directed toward the object side and a positive meniscus lens L7 having a convex surface directed toward the object side, and has a negative refracting power as a whole. Yes. The negative meniscus lens L6 corresponds to the lens LA, and the positive meniscus lens L7 corresponds to the lens LB.

  The fourth lens group G4 includes a positive biconvex lens L8, and has a positive refractive power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves to the image side, the second lens group G2 moves to the object side integrally with the aperture stop S, and the third lens group G3. Moves to the object side, and the fourth lens group G4 moves to the image side.

  The aspherical surfaces are the object-side surface of the negative biconcave lens L1 in the first lens group G1, the image-side surface of the positive meniscus lens L2 with the convex surface facing the object side, and the positive biconvex lens L3 in the second lens group G2. Double-sided, object-side surface of positive biconvex lens L4, object-side surface of negative meniscus lens L6 with the convex surface facing the object side in third lens group G3, object side of positive biconvex lens L8 in fourth lens group G4 It is provided on the surface.

  Next, a zoom lens according to embodiment 2 of the present invention will be described. FIGS. 3A and 3B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to the second embodiment of the present invention when focusing on an object point at infinity, where FIG. 3A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  4A and 4B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 2 is focused on an object point at infinity, where FIG. 4A is a wide angle end, and FIG. 4B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 3, the zoom lens of Example 2 includes, in order from the object side, the first lens group G1, the second lens group G2, the aperture stop S, the third lens group G3, and the fourth lens group. G4.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface directed toward the object side, a prism L2, and a cemented lens of a positive biconvex lens L3 and a negative biconcave lens L4, and has a negative refractive power as a whole. ing.

  The second lens group G2 includes a cemented lens which includes a positive biconvex lens L5 and a negative meniscus lens L6 having a convex surface directed toward the image side, and has a positive refractive power as a whole.

  The third lens group G3 includes a cemented lens which is formed by a negative biconcave lens L7 and a positive meniscus lens L8 having a convex surface directed toward the object side, and has a negative refracting power as a whole. The negative biconcave lens L7 corresponds to the lens LA, and the positive meniscus lens L8 corresponds to the lens LB.

  The fourth lens group G4 includes a cemented lens which is formed by a positive biconvex lens L9 and a negative meniscus lens L10 having a convex surface directed toward the image side, and has a positive refracting power as a whole.

  When zooming from the wide angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved to the object side, the aperture stop S is fixed, and the third lens group G3 is moved to the image side. The fourth lens group G4 moves to the image side.

  The aspherical surfaces are the image side surface of the negative meniscus lens L1 having a convex surface facing the object side in the first lens group G1, the object side surface of the positive biconvex lens L3, and the positive biconvex lens L3 in the second lens group G2. It is provided on the object side surface, the object side surface of the positive biconvex lens L9 in the fourth lens group G4.

  Next, a zoom lens according to embodiment 3 of the present invention will be described. FIGS. 5A and 5B are cross-sectional views along the optical axis showing an optical configuration when focusing on an object point at infinity of a zoom lens according to Example 3 of the present invention, where FIG. 5A is a wide angle end, and FIG. 5B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  6A and 6B are diagrams illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 3 is focused on an object point at infinity, in which FIG. 6A is a wide-angle end, and FIG. 6B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 5, the zoom lens of Example 3 includes, in order from the object side, the first lens group G1, the second lens group G2, the aperture stop S, the third lens group G3, and the fourth lens group. G4 and the fifth lens group G5 are included.

  The first lens group G1 includes a negative meniscus lens L1, a prism L2, and a positive biconvex lens L3 having a convex surface directed toward the object side, and has a positive refractive power as a whole.

  The second lens group G2 includes a cemented lens of a negative biconcave lens L4 and a positive biconvex lens L5, and has a negative refractive power as a whole.

  The third lens group G3 includes a cemented lens which is formed by a positive biconvex lens L6 and a negative meniscus lens L7 having a convex surface directed toward the image side, and has a positive refracting power as a whole.

  The fourth lens group G4 includes a cemented lens which is formed by a negative meniscus lens L8 having a convex surface directed toward the object side and a positive meniscus lens L9 having a convex surface directed toward the object side, and has a negative refracting power as a whole. Yes. The negative meniscus lens L8 corresponds to the lens LA, and the positive meniscus lens L9 corresponds to the lens LB.

  The fifth lens group G5 includes a positive meniscus lens L10 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved to the image side, the aperture stop S is fixed, and the third lens group G3 is moved to the object side. The fourth lens group G4 moves toward the object side, and the fifth lens group G5 moves toward the object side.

  The aspherical surfaces are the image side surface of the negative meniscus lens L1 having a convex surface facing the object side in the first lens group G1, the object side surface of the positive biconvex lens L3, and the negative biconcave lens L4 in the second lens group G2. An object-side surface, an object-side surface of a positive biconvex lens L6 in the third lens group G3, an image-side surface of a positive meniscus lens L9 having a convex surface facing the object side in the fourth lens group G4, and a fifth lens group It is provided on the object side surface of the positive meniscus lens L10 having a convex surface facing the object side in G5.

  Next, a zoom lens according to embodiment 4 of the present invention will be described. FIGS. 7A and 7B are cross-sectional views along the optical axis showing the optical configuration when focusing on an object point at infinity of a zoom lens according to Example 4 of the present invention, where FIG. 7A is a wide-angle end, and FIG. 7B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  8A and 8B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 4 is focused on an object point at infinity, in which FIG. 8A is a wide-angle end, and FIG. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 7, the zoom lens of Example 4 includes, in order from the object side, the first lens group G1, the second lens group G2, the aperture stop S, the third lens group G3, and the fourth lens group. G4 and the fifth lens group G5.

  The first lens group G1 includes a negative meniscus lens L1 having a convex surface facing the object side, a prism L2, and a cemented lens of a negative meniscus lens L3 having a convex surface facing the object side and a positive biconvex lens L4. It has a refractive power of

  The second lens group G2 includes a cemented lens including a negative meniscus lens L5 having a convex surface directed toward the object side, a negative biconcave lens L6, and a positive meniscus lens L7 having a convex surface directed toward the object side, and has a negative refracting power as a whole. have.

  The third lens group G3 includes a positive biconvex lens L8, and a cemented lens of a positive biconvex lens L9 and a negative biconcave lens L10, and has a positive refractive power as a whole.

  The fourth lens group G4 includes a positive meniscus lens L11 having a convex surface directed toward the object side, and has a positive refracting power as a whole.

  The fifth lens group G5 includes a cemented lens of a positive meniscus lens L12 having a convex surface facing the image side and a negative meniscus lens L13 having a convex surface facing the image side, and a positive meniscus lens L14 having a convex surface facing the image side. , Has a negative refractive power as a whole. The negative meniscus lens L13 with the convex surface facing the image side corresponds to the lens LA, and the positive meniscus lens L12 with the convex surface facing the image side corresponds to the lens LB.

  When zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved to the image side, the aperture stop S is fixed, and the third lens group G3 is moved to the object side. Then, the fourth lens group G4 once moves to the object side, then the moving direction reverses and moves to the image side, and the fifth lens group G5 is fixed.

  The aspherical surfaces are surfaces on both sides of the negative meniscus lens L3 having a convex surface facing the object in the first lens group G1, surfaces on the image side (both surfaces) of the positive biconvex lens L4, and objects in the second lens group G2. Image side surface of the negative meniscus lens L5 with the convex surface facing side, surfaces on both sides of the positive biconvex lens L7 in the third lens group G3, and positive meniscus lens L11 with the convex surface facing the object side in the fourth lens group G4 Of the positive meniscus lens L12 having a convex surface facing the image side in the fifth lens group G5.

  Next, numerical data of optical members constituting the zoom lens of each of the above embodiments will be listed. In the numerical data of each embodiment, r1, r2,... Are the curvature radii of the lens surfaces, d1, d2,... Are the thickness or air spacing of each lens, and nd1, nd2,. Are the Abbe number of each lens, Fno. Is the F number, f is the focal length of the entire system, and D0 is the distance from the object to the first surface. Further, asp indicates an aspheric surface, and STO indicates an aperture.

The aspherical shape is expressed by the following equation when the optical axis direction is z, the direction orthogonal to the optical axis is y, the conical coefficient is K, and the aspherical coefficients are A4, A6, A8, and A10. .
z = (y ² / r) / [1+ {1− (1 + K) (y / r) ² } ^1/2 ]
+ A4y ⁴ + A6y ⁶ + A8y ⁸ + A10y ¹⁰
E represents a power of 10. The symbols of these specification values are common to the numerical data of the examples described later.

Numerical example 1
Unit mm
Surface data surface number rd nd νd
Object ∞ ∞
1 * -16.1471 0.8000 1.49700 81.54
2 9.8983 0.7034 1.63494 23.22
3 * 18.3954 Variable
4 (STO) ∞ 0.3000
5 * 7.4687 1.8349 1.83481 42.71
6 * -20.6887 0.0791
7 * 8.5392 1.7940 1.83481 42.71
8 -12.7563 0.4000 1.80810 22.76
9 4.2222 Variable
10 * 11.2017 0.6000 1.65844 50.88
11 4.2000 0.5000 1.58313 28.00
12 5.0729 Variable
13 * 409.5902 1.3800 1.94595 25.00
14 -9.6000 Variable
15 ∞ 0.5000 1.54771 62.84
16 ∞ 0.5000
17 ∞ 0.5000 1.51633 64.14
18 ∞ 0.1068
Image plane ∞

Aspheric data first surface
K = 0.0862, A6 = 4.5520E-06, A8 = -4.0064E-08
Third side
K = -13.3000, A4 = 1.8286E-04, A6 = 4.2739E-06, A8 = -8.3483E-09
5th page
K = -1.5711, A4 = -2.5602E-04, A6 = -1.9098E-05, A8 = -2.8574E-06
6th page
K = -4.8575, A4 = -4.0024E-04, A6 = -1.4688E-05, A8 = -1.6741E-06
7th page
K = -0.4419, A4 = -9.3000E-05, A6 = 8.3888E-06, A8 = 1.7566E-06, A10 = 1.7396E-08
10th page
K = 0.0000, A4 = -3.7405E-04, A6 = -6.8373E-05, A8 = 2.5528E-06
13th page
K = 0.0000, A4 = -2.3214E-04, A6 = 1.5370E-05

Various data zoom ratio 2.91
Wide angle Medium telephoto focal length 6.61204 11.38846 19.22979
F number 2.1218 2.6136 3.4746
Angle of view 31.47 16.99 10.17
Image height 3.600 3.600 3.600
Total lens length 32.1068 24.3050 21.7859
BF 0.10677 0.10677 0.10677
d3 15.93152 5.87283 0.56074
d9 1.53860 2.97240 5.47277
d12 2.89560 3.78100 4.98719
d14 1.74294 1.68066 0.76713

Zoom lens group data group Start surface Focal length
1 1 -19.25104
2 4 8.29893
3 10 -14.33112
4 13 9.93204

Glass material refractive index table ... List of refractive indexes by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
L7 1.583128 1.577206 1.598029 1.611001 1.622720 (LB)
L2 1.634937 1.627308 1.654649 1.672362 1.688770
L8 1.945946 1.935074 1.972908 1.995802 2.016016
L9 1.547710 1.545046 1.553762 1.558428 1.562261
L6 1.658441 1.654553 1.667495 1.673944 1.679006 (LA)
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L1 1.496999 1.495136 1.501231 1.504507 1.507205
L3, L4 1.834807 1.828975 1.848520 1.859548 1.868911
L5 1.808095 1.798009 1.833513 1.855904 1.876580

Numerical example 2
Unit mm
Surface data surface number rd nd νd
Object ∞ ∞
1 35.8318 1.1000 1.74320 49.34
2 * 9.9416 3.0000
3 ∞ 12.5000 1.80100 34.97
4 ∞ 0.4000
5 * 27.3334 2.9000 1.80610 40.92
6 -20.1421 0.7000 1.51823 58.90
7 12.1308 Variable
8 * 12.2212 4.0000 1.49700 81.54
9 -12.1288 0.6000 1.80810 22.76
10 -17.7093 Variable
11 (STO) ∞ Variable
12 -16.1982 0.7000 1.48749 70.23
13 9.1167 0.7000 1.75000 37.99
14 19.4556 Variable
15 * 14.0048 3.5000 1.74320 49.34
16 -5.8761 0.7000 1.84666 23.78
17 -14.7458 Variable
18 ∞ 1.4400 1.54771 62.84
19 ∞ 0.8000
20 ∞ 0.6000 1.51633 64.14
21 ∞ 1.3602
Image plane ∞

Aspheric data 2nd surface
K = -0.2899, A4 = 6.7433E-05, A6 = 2.3698E-07
5th page
K = -0.4004, A4 = 6.6925E-05, A6 = -1.7249E-07
8th page
K = -0.1783, A4 = -8.6570E-05, A6 = 1.7736E-08
15th page
K = -0.0497, A4 = -1.5095E-04, A6 = 6.4327E-07

Various data zoom ratio 3.00
Wide angle Medium telephoto focal length 5.99592 10.39605 17.99270
F number 2.8466 3.3814 3.7889
Angle of view 30.46 17.74 10.30
Image height 3.320 3.320 3.320
Total lens length 64.4369 64.4350 64.4372
BF 1.36016 1.36016 1.36016
d7 14.06937 8.08687 0.79809
d10 1.60258 7.58546 14.87408
d11 1.40333 6.36198 9.56490
d14 6.46766 4.26456 3.00535
d17 5.89383 3.13403 1.19449

Zoom lens group data group Start surface Focal length
1 1 -19.42672
2 8 17.17980
3 12 -24.99862
4 15 11.38659

Glass material refractive index table ... List of refractive indexes by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
L8 1.749998 1.744191 1.763931 1.775349 1.785149 (LB)
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L7 1.487490 1.485344 1.492285 1.495743 1.498455 (LA)
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L5 1.496999 1.495136 1.501231 1.504507 1.507205
L3 1.806098 1.800248 1.819945 1.831174 1.840781
L1, L9 1.743198 1.738653 1.753716 1.762047 1.769040
L2 1.800999 1.794275 1.817182 1.830614 1.842361
L6 1.808095 1.798009 1.833513 1.855904 1.876580
L4 1.518229 1.515556 1.524354 1.529155 1.533151
L10 1.846660 1.836491 1.872096 1.894187 1.914278

Numerical Example 3
Unit mm
Surface data surface number rd nd νd
Object ∞ ∞
1 28.9647 0.9000 1.80518 25.42
2 * 10.1887 3.2000
3 ∞ 12.0000 1.80610 40.92
4 ∞ 0.2000
5 * 55.2953 2.4000 1.80610 40.92
6 -21.2735 Variable
7 * -9.8278 0.6000 1.69350 53.18
8 48.9185 1.4000 1.80810 22.76
9 -42.5878 Variable
10 (STO) ∞ Variable
11 * 8.2366 4.0000 1.69350 53.21
12 -6.9023 0.6000 1.80810 22.76
13 -15.4535 Variable
14 16.8506 0.6000 1.80100 34.97
15 5.0000 0.5000 1.61000 28.01
16 * 6.3170 Variable
17 * 14.0429 1.2000 1.49700 81.54
18 46.4092 Variable
19 ∞ 1.5000 1.54771 62.84
20 ∞ 0.8000
21 ∞ 0.7500 1.51633 64.14
22 ∞ 1.3604
Image plane ∞

Aspheric data 2nd surface
K = 0.0623, A4 = 1.9497E-06, A6 = 2.8588E-08
5th page
K = 3.8407, A4 = 1.9300E-05, A6 = 1.0151E-07
7th page
K = -0.4033, A4 = 1.1913E-04, A6 = -2.2903E-09
11th page
K = 0.0156, A4 = -3.1561E-04, A6 = -1.7261E-06
16th page
K = -0.2705, A4 = 4.5027E-04, A6 = 1.8076E-05
17th page
K = -1.5255, A4 = 1.4779E-04, A6 = 1.6589E-06

Various data zoom ratio 3.00
Wide angle Medium telephoto focal length 6.00121 10.39889 17.99798
F number 2.8002 3.4359 5.1359
Angle of view 33.88 17.58 10.35
Image height 3.320 3.320 3.320
Total lens length 60.8486 60.8482 60.8481
BF 1.36039 1.36039 1.36039
d6 0.99921 8.64865 11.76088
d9 12.15876 4.50990 1.39710
d10 9.78046 7.23051 1.19879
d13 2.65158 1.87916 0.80149
d16 1.50039 4.72430 11.67878
d18 1.74781 1.84574 2.00113

Zoom lens group data group Start surface Focal length
1 1 33.94191
2 7 -20.95836
3 11 8.96382
4 14 -11.79277
5 17 40.02194

Glass material refractive index table ... List of refractive indexes by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
L9 1.609998 1.603792 1.625567 1.639063 1.651211 (LB)
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L8 1.800999 1.794275 1.817182 1.829998 1.840794 (LA)
L4 1.693500 1.689551 1.702591 1.709739 1.715701
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L10 1.496999 1.495136 1.501231 1.504507 1.507205
L2, L3 1.806098 1.800248 1.819945 1.831174 1.840781
L6 1.693501 1.689548 1.702582 1.709715 1.715662
L5, L7 1.808095 1.798009 1.833513 1.855904 1.876580
L1 1.805181 1.796106 1.827775 1.847286 1.864939

Numerical Example 4
Unit mm
Surface data surface number rd nd νd
Object ∞ ∞
1 37.2267 1.2000 2.00330 28.27
2 11.9354 3.3000
3 ∞ 13.8795 1.80610 40.92
4 ∞ 0.2000
5 * 24.7701 0.0600 1.63494 23.20
6 * 14.9283 3.0000 1.74320 49.34
7 * -21.8746 Variable
8 56.2309 0.4500 1.83481 42.71
9 * 14.4713 1.5000
10 -14.4490 0.4500
11 15.3143 1.4000 1.92286 18.90
12 78.8167 Variable
13 (STO) ∞ Variable
14 * 7.8671 1.9381 1.74320 49.34
15 * -33.7520 0.1500
16 5.6480 2.9134 1.61800 63.33
17 -11.6536 0.5000 2.09500 29.40
18 4.6890 Variable
19 * 6.5952 1.2000 1.52540 56.25
20 12.4508 Variable
21 * -7.9790 0.7000 1.63494 23.20
22 -5.3291 0.5000 2.09500 29.40
23 -28.4499 0.1500
24 -46.9330 2.4331 1.60562 43.70
25 -6.4249 Variable
26 ∞ 0.8000 1.51633 64.14
27 ∞ 0.8001
Image plane ∞

Aspheric data 5th surface
K = 0.0571, A4 = -3.1971E-05, A6 = 3.6157E-08, A8 = -2.2151E-09
6th page
K = 0.0000, A4 = 5.1470E-07, A6 = -8.4865E-07, A8 = 2.3540E-10
7th page
K = 0.0000, A4 = 8.7273E-07, A6 = 4.9039E-09, A8 = -1.9092E-09
9th page
K = 0.0953, A4 = 1.3499E-04, A6 = -2.7202E-06, A8 = 3.8348E-07
14th page
K = 0.0573, A4 = -8.7670E-06, A6 = 4.5811E-06, A8 = 5.9522E-08
15th page
K = 0.1429, A4 = 7.9788E-05, A6 = 4.7779E-06, A8 = 3.8238E-08
19th page
K = -0.3649, A4 = -1.0076E-03, A6 = -1.5861E-05, A8 = -1.9630E-06
21st page
K = 0.0171, A4 = 1.0046E-03, A6 = 3.1205E-05, A8 = -8.0555E-07

Various data zoom ratio 5.00
Wide angle Medium telephoto focal length 6.19888 13.89902 30.99766
F number 3.1613 3.9444 5.0048
Angle of view 38.33 16.09 6.99
Image height 3.840 3.840 3.840
Total lens length 65.0013 65.0065 65.0013
BF 0.80008 0.80008 0.80008
d7 0.60030 7.65544 13.26505
d12 14.06050 7.00575 1.39567
d13 6.60312 4.10996 1.19420
d18 2.00082 3.58064 8.91986
d20 3.51241 4.43678 2.00231
d25 0.70000 0.70000 0.70000

Zoom lens group data group Start surface Focal length
1 1 19.26311
2 8 -10.43611
4 14 11.93780
5 19 24.93134
6 21 -54.62674

Glass material refractive index table ... List of refractive indexes by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
L12 1.634937 1.627302 1.654667 1.672395 1.688831 (LB)
L10 2.094997 2.084179 2.121419 2.143451 2.162629
L13 2.094997 2.084179 2.121419 2.142880 2.161325 (LA)
LPF 1.605620 1.601507 1.615364 1.623290 1.630102
CG 1.516330 1.513855 1.521905 1.526213 1.529768
L2 1.806098 1.800248 1.819945 1.831173 1.840781
L5 1.834807 1.828975 1.848520 1.859547 1.868911
L1 2.003300 1.993011 2.028497 2.049714 2.068441
L6 1.729157 1.725101 1.738436 1.745696 1.751731
L4, L8 1.743198 1.738653 1.753716 1.762046 1.769040
L7 1.922860 1.909158 1.957996 1.989713 2.019763
L9 1.618000 1.615036 1.624794 1.630103 1.634506
L11 1.525400 1.522460 1.531800 1.537220 1.543549

Next, the values of parameters in each example are listed.
Example 1 Example 2 Example 3 Example 4
fw 6.612 5.996 6.001 6.199
y ₁₀ 3.6 3.32 3.32 3.84
nd (LA) 1.65844 1.48749 1.80100 2.09500
νd (LA) 50.88 70.23 34.97 29.4
θgF (LA) 0.4984 0.4982 0.5595 0.5763
β (LA) 0.5813 0.6127 0.6165 0.6242
θhg (LA) 0.3912 0.3909 0.4713 0.4953
βhg (LA) 0.5057 0.5489 0.5500 0.5615
nd (LB) 1.58313 1.75000 1.61000 1.63494
νd (LB) 28.00 37.99 28.01 23.20
θgF (LB) 0.6230 0.5784 0.6198 0.6478
β (LB) 0.6686 0.6403 0.6655 0.6856
θhg (LB) 0.5628 0.4965 0.5579 0.6006
y ₀₇ 2.52 2.324 2.324 2.688
tan _ω07 0.40203 0.40271 0.42174 0.48393
t1 0.5 0.7 0.5 0.7

Next, the values of the conditional expressions in each example are listed. Note that () indicates that the condition is not satisfied.
Example 1 Example 2 Example 3 Example 4
(1) β (LA) 0.5813 0.6127 0.6165 0.6242
(2) νd (LA) 50.88 70.23 34.97 29.40
(3) βhg (LA) 0.5057 0.5489 0.5500 0.5615
(4) θgF (LA) -θgF (LB) -0.1246 -0.0802 -0.0603 -0.0715
(5) θhg (LA) -θhg (LB) -0.1716 -0.1056 -0.0866 -0.1053
(6) νd (LA) -νd (LB) 22.88 32.24 6.96 6.20
(9) y ₀₇ / (fw ・ tan _ω07 ) 0.948 0.962 0.918 0.896
(10) β (LB) (0.6686) (0.6403) (0.6655) 0.6856
(11) νd (LB) 28.00 (37.99) 28.01 23.20
(12) β (LB) 0.6686 0.6403 0.6655 0.6856
(13) νd (LB) (28.00) 37.99 (28.01) (23.20)
(14) β (LB) 0.6686 0.6403 0.6655 (0.6856)
(15) νd (LB) 28.00 (37.99) 28.01 23.20
(16) nd (LA) 1.65844 1.48749 1.80100 2.09500
(17) t1 0.5 0.7 0.5 0.7

(Example 5)
The imaging optical system of the present invention as described above is a photographing apparatus for photographing an image of an object with an electronic image sensor such as a CCD or CMOS, in particular, a digital camera, a video camera, a personal computer or an example of an information processing apparatus, a telephone. It can be used for portable terminals, especially mobile phones that are convenient to carry. The embodiment is illustrated below.

  FIGS. 9 to 11 are conceptual diagrams of structures in which the imaging optical system according to the present invention is incorporated in a photographing optical system 41 of a digital camera. 9 is a front perspective view showing the appearance of the digital camera 40, FIG. 10 is a rear perspective view thereof, and FIG. 11 is a cross-sectional view showing an optical configuration of the digital camera 40.

  In this example, the digital camera 40 includes a photographing optical system 41 having a photographing optical path 42, a finder optical system 43 having a finder optical path 44, a shutter 45, a flash 46, a liquid crystal display monitor 47, and the like. Then, when the photographer presses the shutter 45 disposed on the upper portion of the camera 40, photographing is performed through the photographing optical system 41, for example, the zoom lens 48 of the first embodiment, in conjunction therewith.

  The object image formed by the photographing optical system 41 is formed on the image pickup surface of the CCD 49. The object image received by the CCD 49 is displayed as an electronic image on the liquid crystal display monitor 47 provided on the back of the camera via the image processing means 51. Further, the image processing means 51 is provided with a memory or the like, and can record a captured electronic image. This memory may be provided separately from the image processing means 51, or may be configured to perform recording and writing electronically using a flexible disk, memory card, MO, or the like.

  Further, a finder objective optical system 53 is disposed on the finder optical path 44. The finder objective optical system 53 includes a cover lens 54, a first prism 10, an aperture stop 2, a second prism 20, and a focusing lens 66. An object image is formed on the imaging surface 67 by the finder objective optical system 53. This object image is formed on the field frame 57 of the Porro prism 55 which is an image erecting member. Behind the Porro prism 55, an eyepiece optical system 59 for guiding an erect image to the observer eyeball E is disposed.

  According to the digital camera 40 configured as described above, an electronic imaging device having a compact and thin zoom lens in which the number of components of the photographing optical system 41 is reduced can be realized. The present invention is not limited to the above-described retractable digital camera, but can also be applied to a folding digital camera that employs a bending optical system.

  Next, a personal computer which is an example of an information processing apparatus in which the imaging optical system of the present invention is incorporated as an objective optical system is shown in FIGS. 12 is a front perspective view of the personal computer 300 with the cover open, FIG. 13 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 14 is a side view of FIG. As shown in FIGS. 12 to 14, the personal computer 300 includes a keyboard 301, information processing means and recording means, a monitor 302, and a photographing optical system 303.

  Here, the keyboard 301 is for an operator to input information from the outside. The information processing means and recording means are not shown. The monitor 302 is for displaying information to the operator. The photographing optical system 303 is for photographing an image of the operator himself or a surrounding area. The monitor 302 may be a liquid crystal display element, a CRT display, or the like. As the liquid crystal display element, there are a transmissive liquid crystal display element that is illuminated from the back by a backlight (not shown), and a reflective liquid crystal display element that reflects and displays light from the front. In the drawing, the photographic optical system 303 is built in the upper right of the monitor 302, but is not limited to that location, and may be anywhere around the monitor 302 or the keyboard 301.

  The photographing optical system 303 includes, on the photographing optical path 304, the objective optical system 100 including, for example, the zoom lens according to the first embodiment, and the electronic imaging element chip 162 that receives an image. These are built in the personal computer 300.

A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the mirror frame.
The object image received by the electronic image sensor chip 162 is input to the processing means of the personal computer 300 via the terminal 166. Finally, the object image is displayed on the monitor 302 as an electronic image. FIG. 12 shows an image 305 taken by the operator as an example. The image 305 can also be displayed on a communication partner's personal computer from a remote location via the processing means. The Internet and telephone are used for image transmission to remote places.

  Next, FIG. 15 shows a telephone, which is an example of an information processing apparatus in which the imaging optical system of the present invention is incorporated as a photographing optical system, particularly a portable telephone that is convenient to carry. 15A is a front view of the mobile phone 400, FIG. 15B is a side view, and FIG. 15C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 15A to 15C, the mobile phone 400 includes a microphone unit 401, a speaker unit 402, an input dial 403, a monitor 404, a photographing optical system 405, an antenna 406, and processing. Means.

  Here, the microphone unit 401 is for inputting an operator's voice as information. The speaker unit 402 is for outputting the voice of the other party. An input dial 403 is used by an operator to input information. The monitor 404 is for displaying information such as a photographed image of the operator himself or the other party, a telephone number, and the like. The antenna 406 is for transmitting and receiving communication radio waves. The processing means (not shown) is for processing image information, communication information, input signals, and the like.

  Here, the monitor 404 is a liquid crystal display element. Further, in the drawing, the arrangement positions of the respective components, in particular, are not limited thereto. The photographing optical system 405 includes an objective optical system 100 disposed on a photographing optical path 407 and an electronic image sensor chip 162 that receives an object image. As the objective optical system 100, for example, the zoom lens of Example 1 is used. These are built in the mobile phone 400.

A cover glass 102 for protecting the objective optical system 100 is disposed at the tip of the mirror frame.
The object image received by the electronic imaging element chip 162 is input to an image processing unit (not shown) via the terminal 166. Finally, the object image is displayed as an electronic image on the monitor 404, the monitor of the communication partner, or both. The processing means includes a signal processing function. When transmitting an image to a communication partner, this function converts information on the object image received by the electronic image sensor chip 162 into a signal that can be transmitted.

  The present invention can take various modifications without departing from the spirit of the present invention.

(A) of the zoom lens according to Example 1 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 3 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 1 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 2 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 6 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 2 is focused on an object point at infinity, where (a) is a wide-angle end, (b) is a middle, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 3 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 3 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. (A) of the zoom lens according to Example 4 of the present invention is a cross-sectional view along the optical axis showing an optical configuration at the time of focusing on an object point at infinity at the wide-angle end, (b) at the middle, and (c) at the telephoto end. is there. FIG. 10 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 4 is focused on an object point at infinity, where (a) is a wide angle end, (b) is an intermediate, and (c). Indicates the state at the telephoto end. It is a front perspective view which shows the external appearance of the digital camera 40 incorporating the zoom optical system by this invention. 2 is a rear perspective view of the digital camera 40. FIG. 2 is a cross-sectional view showing an optical configuration of a digital camera 40. FIG. 1 is a front perspective view of a state in which a cover of a personal computer 300 which is an example of an information processing apparatus in which a zoom optical system of the present invention is built as an objective optical system is opened. 2 is a cross-sectional view of a photographing optical system 303 of a personal computer 300. FIG. 2 is a side view of a personal computer 300. FIG. 1A and 1B are views showing a mobile phone as an example of an information processing apparatus in which the zoom optical system of the present invention is built in as a photographing optical system, where FIG. 1A is a front view of the mobile phone 400, FIG. FIG. 6 is a cross-sectional view of the photographing optical system 405.

Explanation of symbols

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group L1 to L10 Each lens LPF Low pass filter CG Cover glass I Imaging surface E Observer eye 40 Digital camera 41 Shooting optics System 42 Optical path for photographing 43 Viewfinder optical system 44 Optical path for viewfinder 45 Shutter 46 Flash 47 LCD monitor 48 Zoom lens 49 CCD
DESCRIPTION OF SYMBOLS 50 Image pick-up surface 51 Processing means 53 Finder objective optical system 55 Porro prism 57 Field frame 59 Eyepiece optical system 66 Focusing lens 67 Imaging surface 100 Objective optical system 102 Cover glass 162 Electronic image pick-up element chip | tip 166 Terminal 300 Personal computer 301 Keyboard 302 Monitor 303 Imaging Optical System 304 Imaging Optical Path 305 Image 400 Mobile Phone 401 Microphone Unit 402 Speaker Unit 403 Input Dial 404 Monitor 405 Imaging Optical System 406 Antenna 407 Imaging Optical Path

Claims (9)

In an imaging optical system having a positive lens group, a negative lens group, and a diaphragm,
The negative lens group is disposed on the image side of the stop,
In an orthogonal coordinate system in which the horizontal axis is νd and the vertical axis is θgF,
θgF = α × νd + β (where α = −0.00163)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (1) and the straight line when the upper limit is set, and the following conditional expression (2) An imaging optical system characterized in that θgF and νd of at least one lens LA constituting the negative lens group are included in both the fixed region and the fixed region.
0.3000 <β <0.6650 (1)
29 <νd <120 (2)
Here, θgF is a partial dispersion ratio (ng−nF) / (nF−nC), νd is an Abbe number (nd−1) / (nF−nC), nd, nC, nF, and ng are d line and C line, respectively. , F-line, and g-line refractive indexes. In an orthogonal coordinate system having a horizontal axis νd and a vertical axis θhg different from the orthogonal coordinate,
θhg = αhg × νd + βhg (where αhg = −0.00225)
When the straight line represented by is set, the area defined by the straight line when the range is the lower limit of the range of the following conditional expression (3) and the straight line when the upper limit is set, and the following conditional expression (2) 2. The imaging optical system according to claim 1, wherein θhg and νd of at least one of the lenses LA constituting the negative lens group are included in both the fixed region and the region.
0.2500 <βhg <0.6220 (3)
29 <νd <120 (2)
Here, .theta.hg is the partial dispersion ratio (nh-ng) / (nF-nC), and nh is the refractive index of the h-line.   The imaging optical system according to claim 1, wherein the lens LA is a lens constituting a cemented lens.   4. The imaging optical system according to claim 1, wherein when a lens having a negative paraxial focal length is a negative lens, the lens LA is a negative lens. 5. When a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is bonded is a positive lens, and satisfies the following conditions. The imaging optical system according to any one of the above.
−0.40 ≦ θgF (LA) −θgF (LB) ≦ −0.04 (4)
Here, θgF (LA) is the partial dispersion ratio (ng−nF) / (nF−nC) of the lens LA, and θgF (LB) is the partial dispersion ratio (ng−nF) / of the mating lens LB to be joined. (NF-nC). 6. When a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is cemented is a positive lens and satisfies the following conditions. The imaging optical system according to any one of the above.
−0.50 ≦ θhg (LA) −θhg (LB) ≦ −0.06 (5)
Here, .theta.hg (LA) is the partial dispersion ratio (nh-ng) / (nF-nC) of the lens LA, and .theta.hg (LB) is the partial dispersion ratio (nh-ng) / of the mating lens LB to be joined. (NF-nC). 7. When a lens having a positive paraxial focal length is used as a positive lens, the counterpart lens LB to which the lens LA is joined is a positive lens, and satisfies the following conditions. The imaging optical system described in 1.
−10 ≦ νd (LA) −νd (LB) (6)
Here, νd (LA) is the Abbe number (nd-1) / (nF-nC) of the lens LA, and νd (LB) is the Abbe number (nd-1) / (nF) of the mating lens LB to be joined. -NC).   The image forming optical system according to claim 1, wherein the image forming optical system is a zoom lens, and a relative distance between the lens groups on the optical axis changes during zooming. Optical system. The imaging optical system according to claim 1, an electronic imaging device, and image data obtained by imaging an image formed through the imaging optical system with the electronic imaging device. Image processing means for processing and outputting as image data in which the shape of the image is changed, and the imaging optical system is a zoom lens, and when the zoom lens is focused on an object point at infinity, the following conditional expression An electronic imaging device characterized by satisfying
0.7 <y ₀₇ / (fw · tan ω _07w ) <0.97 (9)
Here, y ₀₇ is y ₀₇ = 0.7 · y, where y ₁₀ is the distance (maximum image height) from the center to the farthest point in the effective imaging plane (in the plane where imaging is possible) of the electronic imaging device. represented as _10, omega _07w angle relative to the central from the optical axis direction of an object point corresponding to an image point formed at a position of y ₀₇ on the imaging surface at the wide angle end, fw is the entire system at the wide-angle end of said zoom lens The focal length.

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