JP2008191301A - Imageing optical system and electronic imaging apparatus having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and thin imaging optical system or the like. <P>SOLUTION: In the imaging optical system having a positive lens group, a negative lens group and a diaphragm, the negative lens group is arranged on the object side of the diaphragm, and has a cemented lens constituted by cementing a plurality of lenses. When setting a straight line expressed by θgF=α×νd+β (provided α=-0.00163) in a rectangular coordinate system having a horizontal axis νd and a vertical axis θgF, θgF and νd of at least one lens LA constituting the cemented lens are included in both an area determined by a straight line showing a lower limit and a straight line showing an upper limit in the range of a conditional expression (1): 0.6400<β<0.9000 and an area determined by a conditional expression (2): 3<νd<50. <P>COPYRIGHT: (C)2008,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, and Patent Document 5 below.

  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 6 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. For this reason, for example, Patent Document 7 below is known as an object of capturing an image while 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 partial dispersion characteristic on the short wavelength side of the optical material is particularly unsatisfactory, color flare that cannot be corrected by the optical system itself is corrected by image processing. Are known.

JP 2002-365545 A JP 2003-43354 A JP 2006-145823 A JP 2005-316047 A JP 2005-352265 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, 4, and 5 are highly dispersed and have a special partial dispersion ratio as compared with 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.

  Further, Patent Documents 6, 7, 8, and 9 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 stop. In the orthogonal coordinate system in which the lens group includes a cemented lens formed by cementing a plurality of lenses, 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) It is characterized in that θgF and νd of at least one lens LA constituting the cemented lens are included in both of the fixed region and the fixed region.
0.6400 <β <0.9000 (1)
3 <νd <50 (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 cemented lens are included in both the fixed region and the region.
0.5700 <βhg <0.9000 (3)
3 <νd <50 (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, when a lens having a positive paraxial focal length is a positive lens, the lens LA is preferably a positive lens.

According to a preferred aspect of the present invention, when a lens having a negative paraxial focal length is a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: It is preferable to do this.
0.08 ≦ θgF (LA) −θgF (LB) ≦ 0.40 (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 negative paraxial focal length is a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: It is preferable to do this.
0.10 ≦ θhg (LA) −θhg (LB) ≦ 0.60 (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 negative paraxial focal length is a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: It is preferable to do this.
νd (LA) −νd (LB) ≦ −15 (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, it is preferable that 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 cemented lens is used for the negative lens group on the object side of the stop. For this reason, particularly in a zoom lens, it is possible to easily suppress fluctuations in the on-axis and lateral chromatic aberration during zooming. Further, even if the number of lenses is small and the lens structure is 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 object side can be made thinner than the stop. For this reason, in addition to making the distance from the surface top on the most object side to the entrance pupil shallow (short), there is also a synergistic effect that other lens groups on the object side than the stop can be made thinner.

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 cemented lens are included.
0.6400 <β <0.9000 (1)
3 <νd <50 (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.

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, the correction of lateral chromatic aberration due to the secondary spectrum, that is, the lateral chromatic aberration of the g-line when achromatic is performed with the F-line and the C-line, becomes insufficient. Therefore, it is difficult to ensure the sharpness of the peripheral portion of the image in the image obtained by imaging.
Further, when this glass material is used for a negative lens, correction of axial chromatic aberration due to the secondary spectrum, that is, g-axis axial chromatic aberration when the achromaticity is applied to the F-line and C-line, becomes insufficient. Therefore, it is difficult to ensure sharpness over the entire screen, particularly in an image obtained by imaging on the telephoto side.

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, axial chromatic aberration due to secondary spectrum, that is, correction of axial chromatic aberration of g-line when achromatic is performed with F-line and C-line is not sufficient. Therefore, it is difficult to ensure sharpness over the entire screen, particularly in an image obtained by imaging on the telephoto side.
Further, when this glass material is used for a negative lens, the lateral chromatic aberration due to the secondary spectrum, that is, the g-line lateral chromatic aberration correction when the F-line and C-line are achromatic is not sufficient. Therefore, it is difficult to ensure the sharpness of the peripheral portion of the image 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).
0.6900 <β <0.9000 (1 ′)
Furthermore, it is more preferable that the following conditional expression (1 ″) is satisfied instead of conditional expression (1).
0.7350 <β <0.7850 (1 ″)

It is more preferable that the following conditional expression (2 ′) is satisfied instead of conditional expression (2).
3 <νd <30 (2 ′)
Furthermore, it is more preferable that the following conditional expression (2 ″) is satisfied instead of conditional expression (2).
3 <νd <17.4 (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 cemented lens are included.
0.5700 <βhg <0.9000 (3)
3 <νd <50 (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, the lateral chromatic aberration due to the secondary spectrum, that is, the lateral chromatic aberration correction of the h-line when achromatic with the F-line and C-line is not sufficient. Therefore, in an image obtained by imaging, purple color flare and color blur are likely to occur in the periphery of the image.
Further, when this glass material is used for a negative lens, the correction of axial chromatic aberration due to the secondary spectrum, that is, the axial chromatic aberration of the h-line when achromatization is performed with the F-line and the C-line becomes insufficient. Therefore, particularly in an image obtained by imaging on the telephoto side, purple color flare and color blur tend to occur over the entire screen.

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 chromatic aberration due to the secondary spectrum, that is, the axial chromatic aberration correction of the h line when the achromaticity is applied to the F line and the C line is not sufficient. Therefore, particularly in an image obtained by imaging on the telephoto side, purple color flare and color blur tend to occur over the entire screen.
Further, when this glass material is used for a negative (concave) lens, the lateral chromatic aberration due to the secondary spectrum, that is, the lateral chromatic aberration correction of the h-line when achromatic with the F-line and C-line is not sufficient. Therefore, in an image obtained by imaging, purple color flare and color blur are likely to occur in the periphery of the image.

It is more preferable that the following conditional expression (3 ′) is satisfied instead of conditional expression (3).
0.6500 <βhg <0.9000 (3 ′)
Furthermore, it is more preferable that the following conditional expression (3 ″) is satisfied instead of conditional expression (3).
0.6700 <βhg <0.9000 (3 ″)

  Incidentally, the lens LA is preferably a positive lens. This lens LA is provided in a negative lens group closer to the object side than the stop. When the lens LA is a positive 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 negative lens, and it is preferable that the following conditional expression (4) is satisfied.
0.08 ≦ θgF (LA) −θgF (LB) ≦ 0.40 (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 positive lens (lens LA) and a negative 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).
0.10 ≦ θgF (LA) −θgF (LB) ≦ 0.30 (4 ′)
Furthermore, it is best to satisfy (4 ″) instead of the conditional expression (4).
0.12 ≦ θgF (LA) −θgF (LB) ≦ 0.25 (4 ″)

The lens LB is a negative lens, and preferably satisfies the following conditional expression (5).
0.10 ≦ θhg (LA) −θhg (LB) ≦ 0.60 (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 positive lens (lens LA) and a negative 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).
0.135 ≦ θhg (LA) −θhg (LB) ≦ 0.55 (5 ′)
Furthermore, it is best to satisfy (5 ″) instead of the conditional expression (5).
0.17 ≦ θhg (LA) −θhg (LB) ≦ 0.50 (5 ″)

The lens LB is a negative lens, and preferably satisfies the following conditional expression (6).
νd (LA) −νd (LB) ≦ −15 (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 positive lens (lens LA) and a negative 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).
νd (LA) −νd (LB) ≦ −25 (6 ′)
Furthermore, it is best to satisfy (6 ″) instead of the conditional expression (6).
νd (LA) −νd (LB) ≦ −35 (6 ″)

  When the cemented lens is composed of three or more lenses, the positive lens having the largest θgF value among the positive lenses is defined as the lens LA, and the negative lens having the smallest θgF value among the negative 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, and 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 first lens on the second lens surface. 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 first lens material (for example, an energy curable transparent resin) is brought into contact with the second lens, and the first lens material is directly adhered to the second 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 the 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 first lens material, it is necessary that the melting point and the transition point are lower than those of the second lens material. A compound lens manufacturing method includes molding. In the molding, there is a method in which the first lens material is brought into contact with the second lens, and the first lens material is directly adhered to the second lens. This method is extremely effective for thinning the lens element.

  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. Further, when the second lens is thinner, the second lens may be in close contact with the first lens.

  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 ) <0.94 (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.
0.6421 <β <0.8000 (10)
50 <νd <120 (11)

  In this case, it is particularly preferable to use a positive lens for satisfying conditional expressions (1) and (2), and a negative lens for satisfying conditional expressions (10) and (11). As a result, correction of chromatic aberration on the axis and magnification (achromaticity on the axis and magnification of the F line and C line) and secondary spectrum (residual chromatic aberration of the g line when the F line and C line are achromatic) are corrected. 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.
0.4000 <β <0.6421 (12)
50 <νd <120 (13)

  In this case, a lens that satisfies the conditional expressions (1) and (2) is preferably a positive lens, and a lens that satisfies the conditional expressions (12) and (13) is preferably a negative lens. As a result, correction of chromatic aberration on the axis and magnification (achromaticity on the axis and magnification of the F line and C line) and secondary spectrum (residual chromatic aberration of the g line when the F line and C line are achromatic) are corrected. 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 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 <0.6421 (14)
3 <νd <50 (15)

  In this case, it is particularly preferable to use a positive lens for satisfying conditional expressions (1) and (2) and a negative lens for satisfying conditional expressions (14) and (15). 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 and C lines).

The lens LA should satisfy the following conditional expression (16).
1.60 <nd <1.85 (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).
1.60 <nd <1.81 (16 ′)
Furthermore, it is more preferable that the following conditional expression (16 ″) is satisfied instead of conditional expression (16).
1.60 <nd <1.77 (16 ")

  In the case where the most object side of the imaging optical system (particularly the zoom lens) is a positive lens group, the above cemented lens is preferably used for a negative lens group adjacent to the front and before the stop. On the other hand, in the case where the most object side of the imaging optical system (particularly the zoom lens) is a negative lens group, the above cemented lens is preferably used for the most negative lens group on the object side. That is, in any lens configuration, it is preferable to use the above cemented lens for the first negative lens group from the object side.

  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 imaging optical system having a four-group configuration is as follows.
Positive, negative, (S), positive, positive negative, positive, (S), negative, positive negative, (S), positive, negative, positive negative, (S), positive, positive, positive The refractive power arrangement in the imaging optical system is the following two.
Positive, negative, (S), positive, negative, positive positive, negative, (S), positive, positive, positive (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 positive / negative / positive / positive configuration, or negative / positive / negative.・ The positive configuration is shared, or the negative, positive, positive, and positive configurations are shared. Further, for example, an imaging optical system having a five-group configuration can be regarded as a modified optical system of an imaging optical system having a four-group configuration of positive, negative, positive, and positive. That is, the configuration of the four-group imaging optical system is defined as three groups on the object side (positive / negative / positive) and the 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.
In addition, regarding the negative / positive / negative / positive / four-group configuration, by adding a positive lens group closest to the object side, as a result, the refractive power arrangement has five groups of positive / negative / positive / negative / positive. The imaging optical system is configured. However, it is better to consider the above-mentioned positive / negative / positive / positive refractive power arrangement as a basic configuration in the five-group configuration in which the refractive power arrangement is positive / negative / positive / negative / positive.

  When the common configuration is positive / negative / positive / positive, the cemented lens is arranged in a negative lens group located closer to the object side than the aperture stop. This negative lens group is a negative lens group located next to the positive lens group disposed closest to the object side. 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 first positive lens group, that is, the most object-side positive lens group has one lens component. This lens component has a positive lens and a negative lens. The positive lens and the negative lens may be joined, but may not be joined (each may be separated). When the positive lens and the negative lens are separately arranged, each of the positive lens and the negative lens can be regarded as one lens component. In this case, it can be said that the negative lens group is composed of two lens components.

  In addition, when the first positive lens group includes two lens components, a prism may be provided. This prism is preferably arranged between two lens components.

  The 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, the lens LA satisfying the conditional expressions (1) and (2) is used for 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 negative lens group may further include another lens component. This other lens component may be arranged on either the object side or the image side of the lens component having the cemented lens.

  The negative lens group may include a prism. This prism is preferably arranged between two lens components when another lens component is arranged on the object side of the lens component having a cemented lens.

  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. Further, it is preferable that the most image side of the cemented lens is a negative lens. The cemented lens may have two negative lenses.

  The second 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. In the second positive lens group, the most image side lens is preferably a negative lens.

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

  In this imaging optical system, two positive lens groups are arranged after the negative lens group. As described above, in the optical system of the modified example, another lens group is arranged between the second and third positive lens groups. This other lens group has one lens component. This lens component may be composed of a cemented lens of a positive lens and a negative lens, or a single lens. This other lens group has a negative refracting power, so that it is easy to reduce the size of the optical system.

  Even when the common configuration is negative / positive / negative / positive, the cemented lens is arranged in the negative lens group located on the object side of the aperture stop. This negative lens group is a negative lens group disposed on the most object side. 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 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. As described above, the lens LA satisfying the conditional expressions (1) and (2) is used for 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 first negative lens group may further include another lens component. This other lens component is composed of a cemented lens of a positive lens and a negative lens. In addition, it is preferable that the other lens component is disposed on the image side with respect to 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 is located on the object side from the aperture stop or located on the image side from the aperture stop. In any case, the first positive lens group has one lens component. This 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. In the first positive lens group, the most image side lens is preferably a negative 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. Alternatively, this lens component may be a single lens.

  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.

  Even when the common configuration is negative / positive / positive / positive, the cemented lens is arranged in the negative lens group located on the object side of the aperture stop. This negative lens group is a negative lens group disposed on the most object side. 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 first negative lens group, that is, the most negative lens group on the object side, has one lens component. This lens component is composed of a cemented lens of a positive lens and a negative lens. As described above, the lens LA satisfying the conditional expressions (1) and (2) is used for 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 first positive lens group has one lens component. This 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 has an aperture stop in the group.

  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. In the first positive lens group, the most image side lens is preferably a negative lens.

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

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

  Also, if the negative, positive, negative, and positive refractive power arrangements have a common configuration, a negative lens group is arranged between the two positive lens groups of the negative, positive, and positive configurations that are the root of the common configuration. Equivalent to. On the other hand, when the negative / positive / positive / positive refractive power arrangement is a basic configuration, this corresponds to the arrangement of a positive lens group (between two positive lens groups). In the case of a negative lens group, the optical system can be easily miniaturized, but in the case of a positive lens group, aberration correction is easy.

  By the way, in the positive / negative / positive / positive common configuration, another lens group may be arranged between the second and third positive lens groups. On the other hand, in the negative / positive / negative / positive common configuration, two positive lens groups (second and third positive lens groups) are arranged on the image side of the first negative lens group. . Then, the second negative lens group can be regarded as another lens group disposed between the second and third positive lens groups. Therefore, this second negative lens group can also have a positive refractive power (for example, negative / positive / positive / positive in the 4-group configuration and positive / negative / positive / positive / positive in the 5-group configuration). If the second negative lens group has a negative refractive power, the optical system can be easily miniaturized, but if it has a positive refractive power, aberration correction is easy.

  In the basic configuration described so far, when the most object side lens unit includes a prism, the position of the most object side lens unit is fixed at the time of zooming from the wide-angle end to the telephoto end. When a lens group other than the most object side lens group includes a prism, the most object side lens group moves monotonously along the optical axis toward the object side during zooming from the wide-angle end to the telephoto end. When the imaging optical system does not include a prism, the lens unit closest to the object moves along a locus convex to the image side during zooming from the wide-angle end to the telephoto end.

  The second positive lens group when the basic configuration is positive / negative / positive / positive, and the first positive lens when the basic configuration is negative / positive / negative / positive or negative / positive / positive / positive. The group moves monotonically toward 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 four types of four-group imaging optical systems. 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 positive fourth lens group. It consists of four lens groups, G4.

  The positive first lens group G1 has one positive 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 positive lens and the negative lens are arranged in this order from the object side.

  The negative second lens group G2 has two lens components. Of the two lens components, one lens component is composed of a cemented lens of a positive lens and a negative lens. 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, it is preferable that the cemented lens in one lens component is configured in the order of the negative lens and the positive lens from the object side. The other lens component is composed of one positive lens. The other lens component may be a positive single lens.

  In addition, a lens LA that satisfies the conditional expressions (1) and (2) is used as the positive 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 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. 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 third lens group G3 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. Furthermore, the cemented lens may include another negative lens. In this case, the positive lens, the negative lens, and the negative lens are preferably arranged in this order.

  Thus, the positive third lens group G3 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 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 lens component is composed of a positive single lens and is disposed on the image side.

  The second type of 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.

  In addition, a lens LA that satisfies the conditional expressions (1) and (2) is used as the positive 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 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 one negative lens. This lens component may be a negative single lens.

  The refractive power of the negative third lens group G3 may be positive. This facilitates aberration correction. However, if the refractive power is negative, the optical system can be easily downsized.

  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 third type of imaging optical system differs in the position of the aperture stop compared to the second type of imaging optical system. That is, the third 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. One lens component and the other lens component are both composed of a cemented lens of a positive lens and a negative lens. Further, it is preferable that the cemented lens in one lens component is configured in the order of the negative lens and the positive lens from the object side. 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 has a prism. The prism is disposed between the two lens components. This prism is used to bend the optical path.

  A lens LA satisfying conditional expressions (1) and (2) is used as the positive lens of the cemented lens in one lens component. The lens LA may be a lens satisfying (1 ') or (1 ") instead of (1) and satisfying (2') or (2") instead of (2).

  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. The cemented lens is preferably configured so that the positive lens and the negative lens are arranged in this order 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.

  The refractive power of the negative third lens group G3 may be positive. This facilitates aberration correction. However, if the refractive power is negative, the optical system can be easily downsized.

  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. The cemented lens is preferably configured so that the positive lens and the negative lens are arranged in this order 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.

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

  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.

  In addition, a lens LA that satisfies the conditional expressions (1) and (2) is used as the positive 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 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. At this time, it is preferable that one lens component is positioned 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. Further, it is preferable to provide a stop in the lens group.

  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 positive third lens group G3 has one lens component. This lens component is composed of one positive lens. This lens component may be a positive single 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.

  Next, an imaging optical system having a five-group configuration will be described. This 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, a positive or negative fourth lens group G4, and a positive Consists of a fifth lens group G5.

  The positive first lens group G1 has one lens component or two lens components. When there is 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 positive lens and the negative lens are arranged in this order from the object side.

  When there are two lens components, one of the two lens components 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.

  When there are two lens components, 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 or two lens components. When the prism is arranged in the positive first lens group G1, 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.

  When no prism is arranged in the positive first lens group G1, 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.

  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 order of the negative lens and the positive lens from the object side.

  In addition, when no prism is disposed in the positive first lens group G1, the negative second lens group G2 may have a prism. The prism is preferably arranged between two negative lens components. This prism is used to bend the optical path. The negative lens component may be bonded to the prism or integrated with the prism (so that one surface of the prism is a negative lens).

  Further, a lens LA that satisfies the conditions (1) and (2) is used as the positive lens of the cemented lens. The lens LA may be a lens that satisfies (1 ') or (1 ") instead of (1) and (2') or (2") instead of (2).

  The positive third lens group G3 has one lens component or two lens components. When a prism is arranged in the positive first lens group G1, 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. The cemented lens is preferably configured so that the positive lens and the negative lens are arranged in this order from the object side.

  When no prism is disposed in the positive first lens group G1, 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.

  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.

  Further, in any one lens component and two lens components, it is preferable that one lens component has a biconvex shape. 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.

  When the positive third lens group G3 has two lens components, the positive third lens group G3 has a positive lens component (one lens component) and a lens component having a cemented lens (the other lens component). It is preferable that a negative lens is provided on the most image side of the cemented 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 or negative fourth lens group G4 has one lens component. This lens component is composed of one positive lens or one negative lens. This lens component may be a positive single lens or a negative single lens.

  Here, the positive or negative fourth lens group G4 has a negative refracting power, so that the optical system can be easily downsized. However, the positive or negative fourth lens group G4 is more easily corrected for aberrations with a positive refractive power.

  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.

  In the above description, an optical system having a four-group configuration in which the refractive power arrangement is negative, positive, negative, and positive 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.

  In each imaging optical system described so far, it is preferable that the lens satisfying conditional expressions (1) and (2) is a positive lens. The positive lens is preferably a lens that satisfies (1 ') or (1 ") instead of (1) and (2') or (2") instead of (2).

  In particular, if the difference is larger by 0.08 or more than the θgF value of the lens to be joined, the correction effect on the secondary spectrum is great. It is even better if it is 0.10 or higher. It is best if it is 0.12 or more.

  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. Further, when there is no lens group including a prism, the lens group closest to the object draws a convex locus on the image side along the optical axis at the time of zooming from the wide-angle end to the telephoto end. When there is a lens group on the object side of the prism, the lens group draws a locus that monotonously moves toward the object side.

  In addition, with the zooming from the wide-angle end to the telephoto end, the third lens group G3 is in the object side when the first lens group G1 is positive, and the second lens group G2 is in the object side when the first lens group G1 is negative. Move monotonously.

  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).
0.1 <t1 <1.4 (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 (5 ′) is satisfied instead of conditional expression (17).
0.1 <t1 <1.0 (17 ′)
Furthermore, it is even better if the following conditional expression (5 ″) is satisfied instead of conditional expression (17).
0.1 <t1 <0.7 (17 ")

  The lens LA is preferably at least one aspherical surface.

Incidentally, the chromatic aberration due to the secondary spectrum includes axial chromatic aberration (chromatic aberration at the focal position) and lateral chromatic aberration. Of these, the above conditions and configuration are very effective for correcting axial chromatic aberration. On the other hand, with respect to lateral chromatic aberration due to the secondary spectrum, aberrations are likely to occur. However, high-order component aberrations related to image height, such as lateral chromatic aberration, can be improved by other means. As an example, there is a means for improving aberration by image processing. Here, it is assumed that the above-described imaging optical system, electronic imaging element, and image processing unit are mounted on the electronic imaging apparatus. The image processing unit can process the image data and output it as image data having a changed shape. An image of a subject is captured using such an electronic imaging device. Image data obtained by imaging is color-separated by an image processing unit, and becomes image data for each color. Subsequently, after changing the shape (the size of the image of the subject) for each image data, these image data are synthesized. As a result, it is possible to prevent deterioration of sharpness in the peripheral portion of the image due to lateral chromatic aberration and occurrence of color blur. This method is particularly effective for an electronic imaging apparatus having an electronic imaging element provided with a color separation mosaic filter. In the case where the electronic imaging apparatus has a plurality of (for each color) electronic imaging elements, it is not necessary to perform color separation on the obtained image data.

  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 provided with (satisfied with) the above conditional expressions and structural features in combination. In this case, the imaging optical system can be further reduced in size and thickness, or better aberration correction and a wider angle 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.

  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 embodiment includes, in order from the object side, a first lens group G1, a second lens group G2, an aperture stop S, 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 positive biconvex lens L1 and a negative meniscus lens L2 having a convex surface directed toward the image side, and has a positive refractive power as a whole.

  The second lens group G2 includes a cemented lens of a negative biconcave lens L3 and a positive meniscus lens L4 having a convex surface directed toward the object side, and a positive meniscus lens L5 having a convex surface directed toward the object side. Have power. The negative biconcave lens L3 corresponds to the lens LB, and the positive meniscus lens L4 with the convex surface facing the object side corresponds to the lens LA.

  The third lens group G3 includes a cemented lens which includes a positive biconvex lens L6, a positive biconvex lens L7, a negative biconcave lens L8, and a negative meniscus lens L9 having a convex surface directed toward the object side, and has a positive refracting power as a whole. have.

  The fourth lens group G4 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 moves to the image side. The third lens group G3 moves to the object side integrally with the aperture stop S, and the fourth lens group G4 once moves to the object side and then reverses the moving direction to move to the image side.

  The aspherical surface is an image side surface of a negative meniscus lens L2 having a convex surface facing the image side in the first lens group G1, and an image side surface of the positive meniscus lens L4 having a convex surface facing the object side in the second lens group G2. A positive meniscus lens L5 having a convex surface facing the object side, an object side surface of the positive biconvex lens L6 in the third lens group G3, an image side surface of the negative meniscus lens L9 having a convex surface facing the object side, It is provided on the surface of the positive meniscus lens L10 having a convex surface facing the object side in the fourth lens group G4. The 18th and 19th surfaces are virtual surfaces.

  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. 3B is an intermediate focal length state. (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 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 biconcave lens L4 and a positive meniscus lens L5 having a convex surface directed toward the object side, and has a negative refracting power as a whole. The biconcave lens L4 corresponds to the lens LB, and the positive meniscus lens L5 corresponds to the lens LA.

  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 negative meniscus lens L8 having a convex surface directed toward the object side, and has a negative refracting power as a whole.

  The fifth lens group G5 includes a positive meniscus lens L9 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. Then, the fourth lens group G4 moves to the object side, and the fifth lens group G5 once moves to the object side, then the moving direction is reversed and 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 negative biconcave lens L4 in the second lens group G2. Object-side surface, image-side surface of positive meniscus lens L5 having a convex surface facing the object side, object-side surface of positive biconvex lens L6 in third lens group G3, and convex surface on the object side in fifth lens group G5 Is provided on the object side surface of the positive meniscus lens L9.

  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. (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.

  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 facing the object side, a prism L3, and a cemented lens of a positive biconvex lens L4 and a negative biconcave lens L5. It has a negative refractive power as a whole. The negative biconcave lens L1 in the first lens group G1 corresponds to the lens LB, and the positive meniscus lens L2 having a convex surface facing the object side corresponds to the lens LA.

  The second lens group G2 includes a biconvex lens L6 and a negative meniscus lens L7 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 L8 and a positive meniscus lens L9 having a convex surface directed toward the object side, and has a negative refracting power as a whole.

  The fourth lens group G4 includes a positive biconvex lens L10 and a negative meniscus lens L11 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. Then, the fourth lens group G4 moves to the image side.

  The aspherical surface is an image side surface of a positive meniscus lens L2 having a convex surface facing the object side in the first lens group G1, an object side surface of the positive biconvex lens L6 in the second lens group G2, and a fourth lens group G4. It is provided on the object side surface of the middle positive biconvex lens L10.

  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. (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, where FIG. 8A is a wide angle end, and FIG. 8B is an intermediate focus. 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 aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. G4.

  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 negative biconcave lens L1 corresponds to the lens LB, and the positive meniscus lens L2 corresponds to the lens LA.

  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 negative biconcave lens L6, and has a negative refracting power as a whole.

  The fourth lens group G4 includes a positive biconvex lens L7, 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 is integrated with the aperture stop S. The third lens group G3 temporarily moves to the image side, and then the moving direction reverses and 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. Both surfaces are provided on the object side surface of the positive biconvex lens L4, the object side surface of the negative biconcave lens L6 in the third lens group G3, and the object side surface of the positive biconvex lens L7 in the fourth lens group G4. .

  Next, a zoom lens according to embodiment 5 of the present invention will be described. 9A and 9B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 5 of the present invention when focusing on an object point at infinity, where FIG. 9A is a wide-angle end, and FIG. 9B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  10A and 10B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 5 is focused on an object point at infinity, where FIG. 10A is a wide-angle end, and FIG. 10B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 9, the zoom lens of Example 5 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.

  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 negative biconcave lens L1 corresponds to the lens LB, and the positive meniscus lens L2 corresponds to the lens LA.

  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 negative biconcave lens L6, and has a negative refracting power as a whole.

  The fourth lens group G4 includes a positive biconvex lens L7, 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 is integrated with the aperture stop S. The third lens group G3 moves to the object side, the fourth lens group G4 once moves to the object side, and then the moving direction is reversed and 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. Both surfaces are provided on the object side surface of the positive biconvex lens L4, the object side surface of the negative biconcave lens L6 in the third lens group G3, and the object side surface of the positive biconvex lens L7 in the fourth lens group G4. .

  Next, a zoom lens according to embodiment 6 of the present invention will be described. 11A and 11B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 5 of the present invention when focusing on an object point at infinity. FIG. 11A is a wide angle end, and FIG. 11B is an intermediate focal length state. (C) is a sectional view at the telephoto end.

  12A and 12B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 6 is focused on an object point at infinity, where FIG. 12A is a wide angle end, and FIG. 12B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 11, the zoom lens of Embodiment 6 includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. G4.

  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 negative biconcave lens L1 corresponds to the lens LB, and the positive meniscus lens L2 corresponds to the lens LA.

  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 negative biconcave lens L6, and has a negative refracting power as a whole.

  The fourth lens group G4 includes a positive biconvex lens L7, 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 is integrated with the aperture stop S. The third lens group G3 moves to the object side, the fourth lens group G4 once moves to the object side, and then the moving direction is reversed and 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. Both surfaces are provided on the object side surface of the positive biconvex lens L4, the object side surface of the negative biconcave lens L6 in the third lens group G3, and the object side surface of the positive biconvex lens L7 in the fourth lens group G4. .

  Next, a zoom lens according to embodiment 7 of the present invention will be described. FIGS. 13A and 13B 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 7 of the present invention. FIG. 13A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  14A and 14B are diagrams showing spherical aberration, astigmatism, distortion aberration, and chromatic aberration of magnification when the zoom lens according to Example 7 is focused on an object point at infinity, where FIG. 14A is a wide angle end, and FIG. 14B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 13, the zoom lens according to the seventh exemplary embodiment 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 cemented lens of a biconvex lens L1 and a negative meniscus lens L2 having a convex surface directed toward the image side, and has a positive refractive power as a whole.

The second lens group G2 includes a negative meniscus lens L3 having a convex surface facing the object side, a prism L4,
It is composed of a cemented lens of a negative meniscus lens L5 having a convex surface facing the object side and a positive meniscus lens L6 having a convex surface facing the object side, and has a negative refractive power as a whole. The negative meniscus lens L5 corresponds to the lens LB, and the positive meniscus lens L6 corresponds to the lens LA.

  The third lens group G3 includes a positive biconvex lens L7, a cemented lens including a positive meniscus lens L8 having a convex surface directed toward the object side and a negative meniscus lens L9 having a convex surface directed toward the object side, and is positively refracted as a whole. Have power.

  The fourth lens group G4 includes a positive meniscus lens L10 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 positive meniscus lens L11 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 moves to the object side, the second lens group G2 is fixed, and the third lens group G3 is integrated with the aperture stop S toward the object side. The fourth lens group G4 moves to the object side, and the fifth lens group G5 is fixed.

  The aspherical surface is an image side surface of the negative meniscus lens L2 having a convex surface facing the image side in the first lens group G1, and an image side surface of the negative meniscus lens L3 having a convex surface facing the object side in the second lens group G2. Surface, the image side surface of the positive meniscus lens L6 with the convex surface facing the object side, the object side surface of the positive biconvex lens L7 in the third lens group G3, and the positive surface with the convex surface facing the object side of the fifth lens group G5 It is provided on the image side surface of the meniscus lens L11.

  Next, a zoom lens according to embodiment 8 of the present invention will be described. 15A and 15B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 8 of the present invention when focusing on an object point at infinity, where FIG. 15A is a wide angle end, and FIG. 15B is an intermediate focal length state. (C) is a cross-sectional view at the telephoto end.

  FIG. 16 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 8 is focused on an object point at infinity, where (a) is a wide angle end and (b) is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 15, the zoom lens of Example 8 includes, in order from the object side, the first lens group G1, the aperture stop S, the second lens group G2, the third lens group G3, and the fourth lens group. G4.

  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 negative biconcave lens L1 corresponds to the lens LB, and the positive meniscus lens L2 corresponds to the lens LA.

  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 negative biconcave lens L6, and has a negative refracting power as a whole.

  The fourth lens group G4 includes a positive biconvex lens L7, 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 is integrated with the aperture stop S. The third lens group G3 temporarily moves to the image side, then the moving direction reverses and 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. Both surfaces are provided on the object side surface of the positive biconvex lens L4, the object side surface of the negative biconcave lens L6 in the third lens group G3, and the object side surface of the positive biconvex lens L7 in the fourth lens group G4. .

  Next, a zoom lens according to embodiment 9 of the present invention will be described. FIGS. 17A and 17B are cross-sectional views along the optical axis showing the optical configuration of the zoom lens according to Example 9 of the present invention when focusing on an object point at infinity, where FIG. 17A is a wide-angle end, and FIG. (C) is a sectional view at the telephoto end.

  18A and 18B are diagrams illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 9 is focused on an object point at infinity, in which FIG. 18A is a wide angle end, and FIG. 18B is an intermediate focus. The distance state, (c) shows the state at the telephoto end.

  As shown in FIG. 17, the zoom lens according to the ninth embodiment includes, in order from the object side, the first lens group G1, the second lens group G2 including the aperture stop S, the third lens group G3, and the fourth lens group. G4.

  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 negative biconcave lens L1 corresponds to the lens LB, and the positive meniscus lens L2 corresponds to the lens LA.

  The second lens group G2 includes a positive biconvex lens L3, an aperture stop S, 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 positive meniscus lens L6 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 positive meniscus lens L7 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 once moves to the image side, then the moving direction reverses and moves to the object side, and the second lens group G2 is integrated with the aperture stop S. The third lens group G3 is moved to the object side, the first lens group G3 is once moved to the image side, the direction of movement is reversed and moved to the object side, and the fourth lens group G4 is fixed.

  The aspherical surface includes both surfaces 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, both surfaces of the positive biconvex lens L3 in the second lens group G2, Provided on the image side surface of the positive meniscus lens L6 with the convex surface facing the image side in the third lens group G3, and on the object side surface of the positive meniscus lens L7 with the convex surface facing the image side in the fourth lens group G4. Yes.

  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.

(Example 1)

r1 = 44.9230 d1 = 2.5268 Nd1 = 1.61800 νd1 = 63.33
r2 = -24.9780 d2 = 0.2000 Nd2 = 1.63547 νd2 = 22.84
r3 = -33.1768 (asp) d3 = D3
r4 = -20.6980 d4 = 0.7000 Nd4 = 1.77250 νd4 = 49.60
r5 = 6.0184 d5 = 0.4000 Nd5 = 1.63547 νd5 = 22.84
r6 = 6.7518 (asp) d6 = 0.8668
r7 = 8.8578 (asp) d7 = 1.2431 Nd7 = 1.83917 νd7 = 23.86
r8 = 15.7785 (asp) d8 = D8
r9 = STO d9 = -0.1000
r10 = 9.6964 (asp) d10 = 1.7977 Nd10 = 1.58313 νd10 = 59.38
r11 = -28.5878 d11 = 0.2000
r12 = 6.8925 d12 = 2.5377 Nd12 = 1.81600 νd12 = 46.62
r13 = -14.2946 d13 = 0.5000 Nd13 = 1.71736 νd13 = 29.52
r14 = 7.5759 d14 = 0.1000 Nd14 = 1.63547 νd14 = 22.84
r15 = 4.5641 (asp) d15 = D15
r16 = 6.6139 (asp) d16 = 1.1456 Nd16 = 1.80610 νd16 = 40.88
r17 = 12.2191 d17 = D17
r18 = ∞ d18 = 0.7600
r19 = ∞ d19 = 0.5000
r20 = ∞ d20 = 0.5556 Nd20 = 1.51633 νd20 = 64.14
r21 = ∞ d21 = D21

Aspheric coefficient third surface
K = 0
A4 = 1.2005E-05
A6 = 5.6733E-08
A8 = 0.0000E + 00

6th page
K = 0.6620
A4 = -8.8163E-04
A6 = 3.9172E-05
A8 = -1.4544E-06

7th page
K = 2.1382
A4 = -1.4025E-03
A6 = 3.1989E-05
A8 = -8.1605E-07

8th page
K = 0
A4 = -9.3781E-04
A6 = 2.6875E-05
A8 = -1.0659E-06
A10 = 4.4761E-08

10th page
K = -0.0945
A4 = -2.3134E-04
A6 = 5.7077E-06
A8 = -6.3431E-07
A10 = 1.8309E-08

15th page
K = 0.5302
A4 = -2.7850E-04
A6 = -3.3081E-07
A8 = -5.0369E-06
A10 = 6.3354E-08

16th page
K = 0.2816
A4 = -4.2228E-04
A6 = 4.4507E-06
A8 = -4.0099E-07

Zoom data
WE ST TE
FL 6.97653 12.06518 20.55387
FNO 1.9533 2.2563 2.5600
D3 0.66325 2.89546 8.24321
D8 10.48492 3.60285 0.66195
D15 6.51982 7.31479 10.26326
D17 1.34169 3.55484 3.39825
D21 0.50685 0.50685 0.50685

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
L2, L4, L9 1.635473 1.627801 1.655618 1.673790 1.690480
L5 1.839170 1.829150 1.864320 1.886193 1.906160
L10 1.806098 1.800238 1.819956 1.831172 1.840747
L6 1.583126 1.580139 1.589960 1.595297 1.599721
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L7 1.816000 1.810749 1.828252 1.837997 1.846185
L3 1.772499 1.767798 1.783374 1.791972 1.799174
L1 1.618000 1.615036 1.624794 1.630103 1.634506
L8 1.717362 1.710332 1.734635 1.749332 1.762468

(Example 2)

r1 = 28.6603 d1 = 0.9000 Nd1 = 1.84666 νd1 = 23.78
r2 = 10.5002 (asp) d2 = 3.0000
r3 = ∞ d3 = 12.0000 Nd3 = 1.80610 νd3 = 40.92
r4 = ∞ d4 = 0.2000
r5 = 32.1236 (asp) d5 = 2.4000 Nd5 = 1.80610 νd5 = 40.92
r6 = -27.2234 d6 = D6
r7 = -17.5310 (asp) d7 = 0.6000 Nd7 = 1.69350 νd7 = 53.18
r8 = 16.1122 d8 = 0.6000 Nd8 = 1.80000 νd8 = 17.30
r9 = 34.3995 (asp) d9 = D9
r10 = STO d10 = D10
r11 = 10.9350 (asp) d11 = 4.0000 Nd11 = 1.83481 νd11 = 42.71
r12 = -7.4017 d12 = 0.6000 Nd12 = 1.80810 νd12 = 22.76
r13 = -26.5473 d13 = D13
r14 = 10.9560 d14 = 1.0000 Nd14 = 1.84666 νd14 = 23.78
r15 = 5.8771 d15 = D15
r16 = 12.5362 (asp) d16 = 2.0000 Nd16 = 1.49700 νd16 = 81.54
r17 = 31.9270 d17 = D17
r18 = ∞ d18 = 1.5000 Nd18 = 1.54771 νd18 = 62.84
r19 = ∞ d19 = 0.8000
r20 = ∞ d20 = 0.7500 Nd20 = 1.51633 νd20 = 64.14
r21 = ∞ d21 = D21

Aspheric coefficient second surface
K = -0.3499
A4 = 1.2776E-05
A6 = 2.8239E-07
A8 = 0.0000E + 00

5th page
K = -0.3428
A4 = 2.8408E-06
A6 = 1.1795E-07
A8 = 0.0000E + 00

7th page
K = -0.2794
A4 = -1.2407E-04
A6 = 3.0845E-06
A8 = 0.0000E + 00

9th page
K = -0.1625
A4 = -1.6863E-04
A6 = 4.4868E-06
A8 = 0.0000E + 00

11th page
K = 0.0563
A4 = -2.3176E-04
A6 = -1.8609E-09
A8 = 0.0000E + 00

16th page
K = -1.5326
A4 = 1.3085E-04
A6 = 3.1037E-06
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.00668 10.39857 17.99302
FNO 2.8002 3.3565 4.7748
D6 0.99746 8.01926 11.55591
D9 11.94945 4.92767 1.39096
D10 8.72015 6.22992 1.19364
D13 2.29144 1.63036 0.80191
D15 1.49943 4.57525 11.18987
D17 2.67739 2.75193 2.00294
D21 1.36041 1.36041 1.36041

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L5 1.800000 1.787370 1.833600 1.866890 1.899621
L4 1.693500 1.689551 1.702591 1.709739 1.715701
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L9 1.496999 1.495136 1.501231 1.504507 1.507205
L2, L3 1.806098 1.800248 1.819945 1.831174 1.840781
L6 1.834807 1.828975 1.848520 1.859548 1.868911
L7 1.808095 1.798009 1.833513 1.855904 1.876580
L1, L8 1.846660 1.836488 1.872096 1.894189 1.914294

(Example 3)

r1 = -148.2378 d1 = 0.8000 Nd1 = 1.61800 νd1 = 63.33
r2 = 10.5000 d2 = 0.9000 Nd2 = 1.70000 νd2 = 20.01
r3 = 12.5375 (asp) d3 = 2.7000
r4 = ∞ d4 = 12.5000 Nd4 = 1.80610 νd4 = 40.92
r5 = ∞ d5 = 0.2000
r6 = 86.3959 d6 = 2.8000 Nd6 = 1.81600 νd6 = 46.62
r7 = -15.5225 d7 = 0.7000 Nd7 = 1.51742 νd7 = 52.43
r8 = 20.9252 d8 = D8
r9 = 16.7269 (asp) d9 = 3.5000 Nd9 = 1.74320 νd9 = 49.34
r10 = -13.1850 d10 = 0.7000 Nd10 = 1.84666 νd10 = 23.78
r11 = -43.9733 d11 = D11
r12 = STO d12 = D12
r13 = -14.1403 d13 = 0.7000 Nd13 = 1.51823 νd13 = 58.90
r14 = 9.5058 d14 = 1.2000 Nd14 = 1.80610 νd14 = 40.92
r15 = 24.0964 d15 = D15
r16 = 12.9283 (asp) d16 = 4.0000 Nd16 = 1.74320 νd16 = 49.34
r17 = -7.9831 d17 = 0.7000 Nd17 = 1.84666 νd17 = 23.78
r18 = -16.7658 d18 = D18
r19 = ∞ d19 = 1.4400 Nd19 = 1.54771 νd19 = 62.84
r20 = ∞ d20 = 0.8000
r21 = ∞ d21 = 0.6000 Nd21 = 1.51633 νd21 = 64.14
r22 = ∞ d22 = D22

Aspheric coefficient third surface
K = -0.1161
A4 = -1.4293E-06
A6 = -1.4339E-07
A8 = 0.0000E + 00

9th page
K = 0.5819
A4 = -2.6544E-05
A6 = -7.4893E-08
A8 = 0.0000E + 00

16th page
K = 0.1991
A4 = -2.1271E-04
A6 = -2.7865E-07
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.00533 10.39582 17.99611
FNO 2.8644 3.2972 3.8315
D8 14.63665 7.78825 0.79919
D11 1.59938 8.44544 15.43690
D12 1.39901 5.38884 9.49803
D15 6.49016 4.75048 3.00021
D18 5.80409 3.55313 1.19508
D22 1.35981 1.35981 1.35981

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L2 1.700000 1.690360 1.725350 1.751590 1.778305
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L3, L9 1.806098 1.800248 1.819945 1.831174 1.840781
L4 1.816000 1.810749 1.828252 1.837997 1.846185
L6, L10 1.743198 1.738653 1.753716 1.762047 1.769040
L5 1.517417 1.514444 1.524313 1.529804 1.534439
L8 1.518229 1.515556 1.524354 1.529155 1.533151
L1 1.618000 1.615036 1.624794 1.630103 1.634506
L7, L11 1.846660 1.836491 1.872096 1.894187 1.914278

Example 4

r1 = -13.2566 (asp) d1 = 0.8000 Nd1 = 1.49700 νd1 = 81.54
r2 = 13.1877 d2 = 0.4237 Nd2 = 1.63494 νd2 = 23.22
r3 = 20.8972 (asp) d3 = D3
r4 = STO d4 = 0.3000
r5 = 8.6234 (asp) d5 = 1.8201 Nd5 = 1.83481 νd5 = 42.71
r6 = -28.1231 (asp) d6 = 0.0791
r7 = 7.0624 (asp) d7 = 1.7619 Nd7 = 1.83481 νd7 = 42.71
r8 = -462.1726 d8 = 0.4000 Nd8 = 1.80810 νd8 = 24.00
r9 = 3.9333 d9 = D9
r10 = -34.2928 (asp) d10 = 0.5000 Nd10 = 1.52542 νd10 = 55.78
r11 = 22.6658 d11 = D11
r12 = 63.7715 (asp) d12 = 1.3800 Nd12 = 1.83481 νd12 = 42.71
r13 = -9.6000 d13 = D13
r14 = ∞ d14 = 0.5000 Nd14 = 1.54771 νd14 = 62.84
r15 = ∞ d15 = 0.5000
r16 = ∞ d16 = 0.5000 Nd16 = 1.51633 νd16 = 64.14
r17 = ∞ d17 = D17

Aspheric coefficient first surface
K = -2.8817
A4 = 0.0000E + 00
A6 = 3.6881E-06
A8 = -5.5124E-08

Third side
K = -2.9323
A4 = 3.6856E-05
A6 = 5.0066E-06
A8 = -5.9251E-08

5th page
K = -1.8270
A4 = -3.4535E-04
A6 = -2.1823E-05
A8 = -7.8527E-08

6th page
K = -5.3587
A4 = -3.7600E-04
A6 = -4.8554E-06
A8 = -2.1415E-07

7th page
K = 0.1274
A4 = 8.3040E-05
A6 = 1.9928E-05
A8 = 5.0707E-07
A10 = 8.1677E-09

10th page
K = 57.7596
A4 = -1.7412E-04
A6 = -4.6146E-06
A8 = 1.1872E-06

12th page
K = 0
A4 = -4.1049E-04
A6 = 3.1634E-06
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.42002 11.01031 18.48954
FNO 1.8604 2.4534 3.4040
D3 14.77955 7.26463 2.92947
D9 2.20000 6.46215 10.54460
D11 2.38783 2.27230 3.76136
D13 3.16783 2.30230 1.60000
D17 0.50018 0.50018 0.50018

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
L5 1.808097 1.798524 1.832190 1.853078 1.871855
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L2 1.634937 1.627308 1.654649 1.673790 1.692286
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L1 1.496999 1.495136 1.501231 1.504507 1.507205
L3, L4, L7 1.834807 1.828975 1.848520 1.859548 1.868911
L6 1.525420 1.522680 1.532100 1.537051 1.540699

(Example 5)

r1 = -14.6626 (asp) d1 = 0.8000 Nd1 = 1.58313 νd1 = 59.38
r2 = 13.6376 d2 = 0.3515 Nd2 = 1.70999 νd2 = 15.00
r3 = 23.8797 (asp) d3 = D3
r4 = STO d4 = 0.3000
r5 = 8.4853 (asp) d5 = 1.7330 Nd5 = 1.83481 νd5 = 42.71
r6 = -18.3330 (asp) d6 = 0.0791
r7 = 8.2088 (asp) d7 = 1.5797 Nd7 = 1.83481 νd7 = 42.71
r8 = -63.5592 d8 = 0.4000 Nd8 = 1.80810 νd8 = 23.00
r9 = 4.3771 d9 = D9
r10 = -53.5288 (asp) d10 = 0.5000 Nd10 = 1.85628 νd10 = 20.67
r11 = 15.5000 d11 = D11
r12 = 108.2217 (asp) d12 = 1.3800 Nd12 = 1.90000 νd12 = 27.00
r13 = -9.6000 d13 = D13
r14 = ∞ d14 = 0.5000 Nd14 = 1.54771 νd14 = 62.84
r15 = ∞ d15 = 0.5000
r16 = ∞ d16 = 0.5000 Nd16 = 1.51633 νd16 = 64.14
r17 = ∞ d17 = D17

Aspheric coefficient first surface
K = -10.2252
A4 = 0.0000E + 00
A6 = 3.2236E-06
A8 = -5.3588E-08

Third side
K = 3.8529
A4 = 1.8071E-04
A6 = 3.8543E-06
A8 = -6.1982E-08

5th page
K = -2.4081
A4 = -4.2584E-04
A6 = -2.8865E-05
A8 = -1.0370E-06

6th page
K = -5.4692
A4 = -4.0486E-04
A6 = -1.6488E-05
A8 = -6.8729E-07

7th page
K = 0.3254
A4 = 1.8098E-04
A6 = 1.9304E-05
A8 = 5.1165E-07
A10 = 4.3288E-08

10th page
K = 0
A4 = -3.6619E-04
A6 = -1.7580E-05
A8 = -1.2817E-07

12th page
K = 0
A4 = -2.5932E-04
A6 = 4.3267E-06
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.41984 11.01046 18.48745
FNO 2.1308 2.6883 3.5779
D3 14.77590 6.40215 1.62729
D9 1.77131 3.83488 7.44342
D11 2.34515 3.70635 5.10940
D13 3.98433 4.12060 4.02033
D17 0.49902 0.49902 0.49902

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
L5 1.808097 1.798151 1.833281 1.855282 1.875184
L6 1.856279 1.844644 1.886065 1.912421 1.936505
L7 1.899997 1.890382 1.923711 1.943729 1.961322
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
L2 1.709995 1.697485 1.744813 1.781729 1.820349
L1 1.583126 1.580139 1.589960 1.595297 1.599721
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L3, L4 1.834807 1.828975 1.848520 1.859548 1.868911

(Example 6)

r1 = -25.4905 (asp) d1 = 0.8000 Nd1 = 1.74320 νd1 = 49.34
r2 = 8.2460 d2 = 0.6848 Nd2 = 1.75000 νd2 = 15.00
r3 = 15.7873 (asp) d3 = D3
r4 = STO d4 = 0.3000
r5 = 7.8777 (asp) d5 = 1.8441 Nd5 = 1.83481 νd5 = 42.71
r6 = -15.9558 (asp) d6 = 0.0791
r7 = 9.3650 (asp) d7 = 1.7013 Nd7 = 1.83481 νd7 = 42.71
r8 = -14.1273 d8 = 0.4000 Nd8 = 1.80810 νd8 = 22.76
r9 = 4.5576 d9 = D9
r10 = -37.4717 (asp) d10 = 0.5000 Nd10 = 2.00000 νd10 = 25.00
r11 = 15.5000 d11 = D11
r12 = 103.2252 (asp) d12 = 1.3800 Nd12 = 1.92000 νd12 = 22.00
r13 = -9.6000 d13 = D13
r14 = ∞ d14 = 0.5000 Nd14 = 1.54771 νd14 = 62.84
r15 = ∞ d15 = 0.5000
r16 = ∞ d16 = 0.5000 Nd16 = 1.51633 νd16 = 64.14
r17 = ∞ d17 = D17

Aspheric coefficient first surface
K = 0.6227
A4 = 0.0000E + 00
A6 = 3.3561E-06
A8 = -1.5540E-09

Third side
K = -0.5547
A4 = -9.9336E-06
A6 = 6.6953E-06
A8 = 9.6741E-08

5th page
K = -1.8589
A4 = -3.2115E-04
A6 = -2.1569E-05
A8 = -9.0860E-07

6th page
K = -8.6329
A4 = -3.5000E-04
A6 = -9.1033E-06
A8 = -7.6128E-07

7th page
K = 0.1074
A4 = 1.4490E-04
A6 = 1.5895E-05
A8 = 7.9815E-07
A10 = 4.1284E-09

10th page
K = 0
A4 = -4.3432E-04
A6 = -3.9156E-05
A8 = 1.3010E-06

12th page
K = 0
A4 = -2.1377E-04
A6 = 2.2393E-06
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.41996 11.01015 18.48954
FNO 2.3074 2.9164 3.9965
D3 13.62838 6.55176 2.97274
D9 1.84065 4.01071 7.85352
D11 2.85247 3.85195 5.22392
D13 3.98922 4.31057 3.46097
D17 0.50005 0.50005 0.50005

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
L2 1.749995 1.736707 1.786700 1.822303 1.857180
L7 1.919996 1.908121 1.949934 1.975893 1.999217
L6 1.999996 1.988484 2.028479 2.052579 2.073790
LPF 1.547710 1.545046 1.553762 1.558428 1.562261
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L3, L4 1.834807 1.828975 1.848520 1.859548 1.868911
L1 1.743198 1.738653 1.753716 1.762047 1.769040
L5 1.808095 1.798009 1.833513 1.855904 1.876580

(Example 7)

r1 = 63.9642 d1 = 4.5000 Nd1 = 1.61800 νd1 = 63.33
r2 = -103.3405 d2 = 0.7000 Nd2 = 1.80810 νd2 = 22.76
r3 = -146.8153 (asp) d3 = D3
r4 = 3889.7579 d4 = 0.8000 Nd4 = 1.69350 νd4 = 53.21
r5 = 11.1476 (asp) d5 = 3.1000
r6 = ∞ d6 = 13.6000 Nd6 = 1.77250 νd6 = 49.60
r7 = ∞ d7 = 0.3000
r8 = 74.8228 d8 = 0.8000 Nd8 = 1.69350 νd8 = 53.21
r9 = 16.0154 d9 = 0.9000 Nd9 = 1.74910 νd9 = 18.01
r10 = 27.3276 (asp) d10 = D10
r11 = STO d11 = 0.5000
r12 = 14.5777 (asp) d12 = 2.7000 Nd12 = 1.83481 νd12 = 42.71
r13 = -1161.5723 d13 = 0.1500
r14 = 8.1745 d14 = 2.7000 Nd14 = 1.75500 νd14 = 52.32
r15 = 21.8470 d15 = 0.5000 Nd15 = 1.80810 νd15 = 22.76
r16 = 5.8267 d16 = D16
r17 = 15.3851 d17 = 2.0000 Nd17 = 1.69680 νd17 = 55.53
r18 = 40.6267 d18 = D18
r19 = 15.4108 d19 = 2.0000 Nd19 = 1.69350 νd19 = 53.21
r20 = 30.8600 (asp) d20 = 1.4000
r21 = ∞ d21 = 1.2000 Nd21 = 1.51633 νd21 = 64.14
r22 = ∞ d22 = D22

Aspheric coefficient third surface
K = 2.5561
A4 = 3.3405E-06
A6 = -1.2865E-08
A8 = 0.0000E + 00

5th page
K = -0.0549
A4 = -1.4371E-05
A6 = 9.7626E-07
A8 = 0.0000E + 00

10th page
K = 0.1065
A4 = -4.5003E-05 *
A6 = -1.3982E-07 *
A8 = 0.0000E + 00

12th page
K = 0
A4 = -3.7488E-05
A6 = 3.1079E-07
A8 = -1.0257E-08

20th page
K = -0.1897
A4 = 1.8595E-05
A6 = 7.5436E-06
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.20005 13.86469 31.00004
FNO 2.8000 3.8202 5.0466
D3 0.80006 13.60944 21.10856
D10 23.87217 12.91536 1.80041
D16 4.05398 13.70232 10.01906
D18 6.73851 8.05119 22.84509
D22 1.50032 1.50032 1.50032

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example lens 587.56 656.27 486.13 435.83 404.66
L6 1.749104 1.737750 1.779338 1.809864 1.840389
CG 1.516330 1.513855 1.521905 1.526214 1.529768
L7 1.834807 1.828975 1.848520 1.859548 1.868911
L4 1.772499 1.767798 1.783374 1.791972 1.799174
L3, L5, L11 1.693501 1.689548 1.702582 1.709715 1.715662
L10 1.696797 1.692974 1.705522 1.712340 1.718005
L2, L9 1.808095 1.798009 1.833513 1.855904 1.876580
L1 1.618000 1.615036 1.624794 1.630103 1.634506
L8 1.754999 1.750624 1.765055 1.772956 1.779544

(Example 8)

r1 = -14.0769 (asp) d1 = 0.8000 Nd1 = 1.49700 νd1 = 81.54
r2 = 13.0399 d2 = 0.4353 Nd2 = 1.63494 νd2 = 23.22
r3 = 20.2304 (asp) d3 = D3
r4 = STO d4 = 0.3000
r5 = 8.3137 (asp) d5 = 1.8433 Nd5 = 1.83481 νd5 = 42.71
r6 = -28.3034 (asp) d6 = 0.0791
r7 = 7.2890 (asp) d7 = 1.7325 Nd7 = 1.83481 νd7 = 42.71
r8 = -234.9510 d8 = 0.4000 Nd8 = 1.80810 νd8 = 22.76
r9 = 3.9450 d9 = D9
r10 = -66.2077 (asp) d10 = 0.5000 Nd10 = 1.52542 νd10 = 55.78
r11 = 15.5000 d11 = D11
r12 = 48.9767 (asp) d12 = 1.3800 Nd12 = 1.83481 νd12 = 42.71
r13 = -9.8000 d13 = D13
r14 = ∞ d14 = 0.5000 Nd14 = 1.54771 νd14 = 62.84
r15 = ∞ d15 = 0.5000
r16 = ∞ d16 = 0.5000 Nd16 = 1.51633 νd16 = 64.14
r17 = ∞ d17 = D17

Aspheric coefficient first surface
K = -1.7279
A4 = 0.0000E + 00
A6 = 5.2480E-06
A8 = -6.5711E-08

Third side
K = -3.2269
A4 = -1.3187E-05
A6 = 6.6781E-06
A8 = -5.4466E-08

5th page
K = -1.8346
A4 = -3.1046E-04
A6 = -2.2024E-05
A8 = -1.4954E-07

6th page
K = -5.2682
A4 = -3.7806E-04
A6 = -3.7399E-06
A8 = -2.7381E-07

7th page
K = 0.1385
A4 = 6.1956E-05
A6 = 1.9211E-05
A8 = 7.5338E-07

10th page
K = 0
A4 = -5.4575E-04
A6 = 1.3347E-05
A8 = 0.0000E + 00

12th page
K = 0
A4 = -2.7359E-04
A6 = 0.0000E + 00
A8 = 0.0000E + 00

Zoom data
WE ST TE
FL 6.42001 11.01031 18.48963
FNO 1.8421 2.4257 3.3791
D3 14.83968 7.18523 2.75812
D9 1.89368 6.35451 10.50890
D11 2.48563 2.12545 3.45724
D13 3.31078 2.34496 1.59995
D17 0.50015 0.50015 0.50015

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
LPF 1.547710 1.545046 1.553762 1.558427 1.562261
L2 1.634940 1.627290 1.654640 1.672908 1.689873
CG 1.516330 1.513855 1.521905 1.526213 1.529768
L1 1.496999 1.495136 1.501231 1.504506 1.507205
L3, L4, L7 1.834807 1.828975 1.848520 1.859547 1.868911
L5 1.808095 1.798009 1.833513 1.855902 1.876580
L6 1.525420 1.522680 1.532100 1.537050 1.540699

Example 9

r1 = -13.7627 (asp) d1 = 0.9000 Nd1 = 1.58313 νd1 = 59.38
r2 = 12.8989 (asp) d2 = 0.4111 Nd2 = 1.63494 νd2 = 23.22
r3 = 26.2119 (asp) d3 = D3
r4 = 4.8424 (asp) d4 = 1.7688 Nd4 = 1.80139 νd4 = 45.46
r5 = -17.6216 (asp) d5 = 0.1000
r6 = STO d6 = 0.2000
r7 = 13.7904 d7 = 1.1300 Nd7 = 1.80100 νd7 = 34.97
r8 = -11.6211 d8 = 0.5000 Nd8 = 1.80518 νd8 = 25.42
r9 = 3.1378 d9 = D9
r10 = -37.4512 d10 = 2.3900 Nd10 = 1.52542 νd10 = 55.78
r11 = -5.6706 (asp) d11 = D11
r12 = -11.6112 (asp) d12 = 1.0000 Nd12 = 1.52542 νd12 = 55.78
r13 = -10.0000 d13 = D13
r14 = ∞ d14 = 0.4000 Nd14 = 1.54771 νd14 = 62.84
r15 = ∞ d15 = 0.2000
r16 = ∞ d16 = 0.5000 Nd16 = 1.51633 νd16 = 64.14
r17 = ∞ d17 = D17

Aspheric coefficient first surface
K = -11.8073
A4 = -4.3618E-04
A6 = 3.8856E-05
A8 = -1.3045E-06
A10 = 1.5738E-08

Second side
K = -68.5453
A4 = 1.2061E-03
A6 = -2.3931E-05
A8 = 2.6541E-07

Third side
K = -77.8212
A4 = 2.0577E-04
A6 = 3.6533E-05
A8 = -1.6516E-06
A10 = 2.1313E-08

4th page
K = -2.5494
A4 = 1.8620E-03
A6 = -9.3264E-05
A8 = -3.0629E-06

5th page
K = -4.6926
A4 = 8.2896E-04
A6 = -1.6537E-04
A8 = 5.9244E-06

11th page
K = -1.6436
A4 = -4.5607E-04
A6 = 1.3950E-06
A8 = 2.7378E-07
A10 = -5.7200E-09

12th page
K = -0.9892
A4 = -2.1476E-03
A6 = 6.9184E-05
A8 = -1.2423E-07

Zoom data
WE ST TE
FL 6.32550 10.48847 18.13667
FNO 2.6010 3.4400 4.9442
D3 12.66696 6.49321 2.33000
D9 2.62413 6.36566 12.95307
D11 2.54197 2.43708 2.55000
D13 0.13000 0.13000 0.13000
D17 0.40276 0.40276 0.40276

[Glass Material Refractive Index Table] ... Refractive index list by wavelength of medium used in this example
GLA 587.56 656.27 486.13 435.84 404.66
LPF 1.547710 1.545046 1.553762 1.558427 1.562262
L2 1.634940 1.627290 1.654640 1.672908 1.689873
L3 1.801390 1.796100 1.813730 1.823569 1.831860
L1 1.583126 1.580139 1.589960 1.595296 1.599721
CG 1.516330 1.513855 1.521905 1.526213 1.529768
L4 1.800999 1.794275 1.817182 1.830612 1.842361
L5 1.805181 1.796106 1.827775 1.847283 1.864939
L6, L7 1.525420 1.522680 1.532100 1.537050 1.540699

Next, the values of parameters in each example are listed.
Example 1 Example 2 Example 3 Example 4 Example 5
fw 6.97653 6.00668 6.00533 6.42002 6.41984
y10 3.8 3.32 3.32 3.6 3.6
nd (LA) 1.63547 1.80000 1.70000 1.63494 1.70999
νd (LA) 22.84 17.30 20.01 23.22 15.00
θgF (LA) 0.6533 0.7201 0.7499 0.7001 0.7800
β (LA) 0.6905 0.7483 0.7825 0.7379 0.8045
θhg (LA) 0.6000 0.7080 0.7635 0.6765 0.8160
βhg (LA) 0.6514 0.7469 0.8085 0.7287 0.8498
nd (LB) 1.77250 1.69350 1.61800 1.49700 1.58913
νd (LB) 49.60 53.18 63.33 81.54 59.38
θgF (LB) 0.5467 0.5480 0.5446 0.5386 0.5438
β (LB) 0.6275 0.6347 0.6478 0.6715 0.6406
θhg (LB) 0.4624 0.4559 0.4523 0.4417 0.4501
y07 2.66 2.324 2.324 2.52 2.52
tanω07 0.40500 0.40543 0.40620 0.41890 0.41843
t1 0.4 0.6 0.9 0.4237 0.3515

Example 6 Example 7 Example 8 Example 9
fw 6.41996 6.20005 6.42001 6.32550
y10 3.6 3.6 3.6 3. 3.84
nd (LA) 1.75000 1.74910 1.63494 1.63494
νd (LA) 15.00 18.01 23.22 23.22
θgF (LA) 0.7122 0.734 0.6679 0.6679
β (LA) 0.7367 0.7634 0.7057 0.7057
θhg (LA) 0.6976 0.734 0.6203 0.6203
βhg (LA) 0.7314 0.7745 0.6725 0.6725
nd (LB) 1.74320 1.69350 1.49700 1.58313
νd (LB) 49.34 53.21 81.54 59.38
θgF (LB) 0.5528 0.5471 0.5373 0.5433
β (LB) 0.6332 0.6338 0.6702 0.6406
θhg (LB) 0.4638 0.4555 0.4428 0.4506
y07 2.52 2.52 2.52 2.688
tanω07 0.41853 0.42749 0.41986 0.43296
t1 0.6848 0.9 0.4353 0.4111

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 Example 5
(1) β (LA) 0.6905 0.7483 0.7825 0.7379 0.8045
(2) νd (LA) 22.84 17.30 20.01 23.22 15.00
(3) βhg (LA) 0.6514 0.7469 0.8085 0.7287 0.8498
(4) θgF (LA) -θgF (LB) 0.1066 0.1721 0.2053 0.1615 0.2362
(5) θhg (LA) -θhg (LB) 0.1376 0.2521 0.3112 0.2348 0.3659
(6) νd (LA) -νd (LB) -26.76 -35.88 -43.32 -58.32 -44.38
(9) y07 / (fw ・ tanω07) 0.9414 0.9543 0.9527 0.9370 0.9381
(10) β (LB) (0.6275) (0.6347) 0.6478 0.6715 (0.6406)
(11) νd (LB) (49.60) 53.18 63.33 81.54 59.38
(12) β (LB) 0.6275 0.6347 (0.6478) (0.6715) 0.6406
(13) νd (LB) (49.60) 53.18 63.33 81.54 59.38
(14) β (LB) 0.6275 0.6347 (0.6478) (0.6715) 0.6406
(15) νd (LB) 49.60 (53.18) (63.33) (81.54) (59.38)
(16) nd (LA) 1.63547 1.80000 1.70000 1.63494 1.70999
(17) t1 0.4 0.6 0.9 0.4237 0.3515

Example 6 Example 7 Example 8 Example 9
(1) β (LA) 0.7367 0.7634 0.7057 0.7057
(2) νd (LA) 15.00 18.01 23.22 23.22
(3) βhg (LA) 0.7314 0.7745 0.6725 0.6725
(4) θgF (LA) -θgF (LB) 0.1594 0.1869 0.1306 0.1246
(5) θhg (LA) -θhg (LB) 0.2338 0.2785 0.1775 0.1697
(6) νd (LA) -νd (LB) -34.34 -35.2 -58.32 -36.16
(9) y07 / (fw tan ω07) 0.9379 0.9508 0.9349 0.9815
(10) β (LB) (0.6332) (0.6338) 0.6702 (0.6406)
(11) νd (LB) (49.34) 53.21 81.54 59.38
(12) β (LB) 0.6332 0.6338 (0.6702) 0.6406
(13) νd (LB) (49.34) 53.21 81.54 59.38
(14) β (LB) 0.6332 0.6338 (0.6702) 0.6406
(15) νd (LB) 49.34 (53.21) (81.54) (59.38)
(16) nd (LA) 1.75000 1.74910 1.63494 1.63494
(17) t1 0.6848 0.9 0.4353 0.4111

(Example 10)
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. 19 to 21 are conceptual diagrams of structures in which the imaging optical system according to the present invention is incorporated in the photographing optical system 41 of a digital camera. 19 is a front perspective view showing the appearance of the digital camera 40, FIG. 20 is a rear perspective view thereof, and FIG. 21 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 part 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 built as an objective optical system is shown in FIGS. 22 is a front perspective view of the personal computer 300 with the cover open, FIG. 23 is a sectional view of the photographing optical system 303 of the personal computer 300, and FIG. 24 is a side view of FIG. 22 to 24, 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. Examples of the liquid crystal display element include a transmissive liquid crystal display element that illuminates from the back with a backlight (not shown), and a reflective liquid crystal display element that reflects and displays light from the front. Further, in the drawing, the photographing optical system 303 is built in the upper right of the monitor 302. However, the imaging optical system 303 is not limited to the place, 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. 22 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. 25 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 which is convenient to carry. 25A is a front view of the mobile phone 400, FIG. 25B is a side view, and FIG. 25C is a cross-sectional view of the photographing optical system 405. As shown in FIGS. 25A to 25C, 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. 6 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, (a) is a wide-angle end, (b) is an intermediate, (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. (A) of the zoom lens according to Example 5 of the present invention is a cross-sectional view along the optical axis showing the 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 lateral chromatic aberration when the zoom lens according to Example 5 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 6 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. 8 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 6 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 7 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. 9 is a diagram illustrating spherical aberration, astigmatism, distortion, and chromatic aberration of magnification when the zoom lens according to Example 7 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 8 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 8 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 9 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 9 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. 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. FIG. 2 is a cross-sectional view of a photographing optical system 303 of a personal computer 300. FIG. 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. 4 is a 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 L11 Each lens LPF Low pass filter CG Cover glass I Imaging surface E Observer's 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 (8)

In an imaging optical system having a positive lens group, a negative lens group, and a diaphragm,
The negative lens group is disposed closer to the object side than the diaphragm,
The negative lens group has a cemented lens formed by cementing a plurality of lenses,
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 cemented lens are included in both the fixed region and the region.
0.6400 <β <0.9000 (1)
3 <νd <50 (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 cemented lens are included in both the fixed region and the region.
0.5700 <βhg <0.9000 (3)
3 <νd <50 (2)
Here, .theta.hg is the partial dispersion ratio (nh-ng) / (nF-nC), and nh is the refractive index of the h-line.   3. The imaging optical system according to claim 1, wherein when a lens having a positive paraxial focal length is a positive lens, the lens LA is a positive lens. 4. When a lens having a negative paraxial focal length is used as a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: The imaging optical system according to any one of the above.
0.08 ≦ θgF (LA) −θgF (LB) ≦ 0.40 (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). 5. When a lens having a negative paraxial focal length is used as a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: The imaging optical system according to any one of the above.
0.10 ≦ θhg (LA) −θhg (LB) ≦ 0.60 (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). 6. When a lens having a negative paraxial focal length is used as a negative lens, the counterpart lens LB to which the lens LA is joined is a negative lens, and satisfies the following conditions: The imaging optical system described in 1.
νd (LA) −νd (LB) ≦ −15 (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 on the optical axis between the lens groups changes during zooming. Optical system. The imaging optical system according to any one of claims 1 to 7, 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.

Images