JP5516127B2 - Zoom lens, imaging device, and zoom lens manufacturing method - Google Patents

Description

  The present invention relates to a zoom lens, an image pickup apparatus, and a zoom lens manufacturing method suitable for a photographing optical system such as a digital single-lens reflex camera, a film camera, and a video camera.

  Conventionally, zoom lenses having a large angle of view have been proposed (see, for example, Patent Document 1).

JP 2004-21223 A

However, among the conventional zoom lenses as described above, those having a large field angle for a 35 mm camera have a large front lens diameter, and thus deviate from the regular filter size. Further, if it is attempted to further increase the angle of view of the zoom lens using the conventional technology, the zoom lens has serious defects with respect to astigmatism, field curvature, coma aberration, and distortion. Therefore, there is room for further improvement in the conventional zoom lens having a large angle of view.
Accordingly, the present invention has been made in view of the above problems, and provides a zoom lens, an imaging device, and a zoom lens manufacturing method that are small in size, correct various aberrations, and have high imaging performance. The purpose is to do.

In order to solve the above problems, the present invention
In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspheric lens component Gb having a shape that shifts to the refractive power of the lens or a shape that has a negative refractive power and the negative refractive power increases toward the periphery,
Performing zooming by changing the air spacing between the front group and the rear group,
Provided is a zoom lens that satisfies the following conditional expression.
0.0406 ≦ (−Fa) / | Fb | < 0.600
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group
The present invention also provides:
In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a negative refractive power or a shape having a negative refractive power and a negative refractive power increasing toward the periphery, and a cemented negative lens of a negative lens and a positive lens Having at least component Gc,
Performing zooming by changing the air spacing between the front group and the rear group,
Provided is a zoom lens that satisfies the following conditional expression.
0.000 <(− Fa) / | Fb | <0.650
0.50 <(− Fc) /Fw≦1.883
However,
Fa: Focal length of the aspheric lens component Ga in the front group
Fb: focal length of the aspheric lens component Gb in the front group
Fc: focal length of the cemented negative lens component Gc in the front group
Fw: focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state
The present invention also provides:
In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a negative refractive power or a shape having a negative refractive power and a negative refractive power increasing toward the periphery, and a cemented negative lens of a negative lens and a positive lens A component Gc, and a positive lens disposed on the image side of the cemented negative lens component Gc,
Performing zooming by changing the air spacing between the front group and the rear group,
Provided is a zoom lens that satisfies the following conditional expression.
0.000 <(-Fa) / | Fb | <0.600
However,
Fa: Focal length of the aspheric lens component Ga in the front group
Fb: focal length of the aspheric lens component Gb in the front group

The present invention also provides
An imaging apparatus comprising the zoom lens is provided.
The present invention also provides
In order from the object side, a zoom lens having a front group having negative refractive power and a rear group having positive refractive power,
In order from the object side, the front group has an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a shape that shifts to the refractive power of the lens or a shape that has a negative refractive power and the negative refractive power increases toward the periphery,
The aspheric lens component Ga and the aspheric lens component Gb satisfy the following conditional expression:
A zoom lens manufacturing method is provided, wherein zooming is performed by changing an air gap between the front group and the rear group.
0.0406 ≦ (−Fa) / | Fb | < 0.600
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group

  According to the present invention, it is possible to provide a zoom lens, an imaging apparatus, and a manufacturing method of a zoom lens that are small in size, correct various aberrations, and have high imaging performance and a large angle of view.

It is sectional drawing which shows the structure of the zoom lens which concerns on 1st Example of this application. (A), (b), and (c) are various aberrations when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 1 of the present application, and focusing on the object at infinity in an intermediate focal length state. It is a figure which shows the various aberrations at the time of the various aberrations at the time, and the infinity object in a telephoto end state. It is sectional drawing which shows the structure of the zoom lens which concerns on 2nd Example of this application. (A), (b), and (c) are various aberrations when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 2 of the present application, and focusing on the object at infinity in the intermediate focal length state, respectively. It is a figure which shows the various aberrations at the time of the various aberrations at the time, and the infinity object in a telephoto end state. It is sectional drawing which shows the structure of the zoom lens which concerns on 3rd Example of this application. (A), (b), and (c) are various aberrations when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 3 of the present application, and focusing on the object at infinity in the intermediate focal length state, respectively. It is a figure which shows the various aberrations at the time of the various aberrations at the time, and the infinity object in a telephoto end state. It is sectional drawing which shows the structure of the zoom lens which concerns on 4th Example of this application. (A), (b), and (c) are various aberrations when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 4 of the present application, and focusing on the object at infinity in the intermediate focal length state, respectively. It is a figure which shows the various aberrations at the time of the various aberrations at the time, and the infinity object in a telephoto end state. It is sectional drawing which shows the structure of the zoom lens which concerns on 5th Example of this application. (A), (b), and (c) are various aberrations when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 5 of the present application, and focusing on the object at infinity in the intermediate focal length state, respectively. It is a figure which shows the various aberrations at the time of the various aberrations at the time, and the infinity object in a telephoto end state. It is a figure which shows the structure of the camera provided with the zoom lens of this application. It is a figure which shows the manufacturing method of the zoom lens of this application.

Hereinafter, the manufacturing method of the zoom lens, the imaging device, and the zoom lens of the present application will be described.
The zoom lens of the present application has a front group having negative refractive power and a rear group having positive refractive power in order from the object side, and the front group has negative refractive power in order from the object side. Aspherical lens component Ga having a shape in which the negative refractive power decreases toward the periphery, and a shape that has a positive refractive power and changes to a negative refractive power toward the periphery, or has a negative refractive power toward the periphery. And an aspheric lens component Gb having a shape in which the negative refractive power increases as it goes, and zooming is performed by changing the air gap between the front group and the rear group, and the following conditional expression ( 1) is satisfied.
(1) 0.000 ≦ (−Fa) / | Fb | <0.650
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group

In general, in a retrofocus zoom lens having a large angle of view, the front group having negative refractive power tends to be large, and the filter diameter tends to be large. Zoom lenses that cover an image area of 35 mm full size, particularly ultra-wide-angle zoom lenses with an angle of view exceeding 2ω = 106 °, have a tendency that the filter size greatly exceeds the 77 mmφ filter, which is a common regular size.
Therefore, in the zoom lens of the present application, the aspheric lens component Ga and the aspheric lens component Gb having the above-described configuration are arranged in the front group in order to reduce the size, particularly the front lens diameter. First, by arranging the aspheric lens component Ga in the front group, various aberrations such as coma, curvature of field, astigmatism, and distortion can be corrected well. The aspherical lens component Ga has a large negative refractive power at a relatively paraxial axis, and has a small negative refractive power at the periphery. This configuration has a feature that it can satisfactorily control off-axis aberrations such as distortion, field curvature, and astigmatism.

However, when the aspherical shape changes remarkably as in the present application, the correction becomes excessive, so that it is necessary to correct distortion and coma with lenses other than the aspherical lens component Ga. Further, if the negative refractive power becomes extremely small around the aspheric lens component Ga, the incident height of oblique rays increases, so that the front lens diameter increases.
Therefore, the zoom lens of the present application introduces an aspheric lens component Gb into the front group in order to improve these two points. The aspheric lens component Gb is a lens that has an effect like a so-called aspheric correction plate. The paraxial refractive power of the aspheric lens component Gb is relatively small and may be positive or negative. A characteristic of the aspheric lens component Gb is that it has a relatively large negative refractive power in the periphery. By such an aspheric lens component Gb, the incident height of oblique rays can be reduced, and the front lens diameter can be reduced. Further, it is possible to satisfactorily correct distortion, coma, curvature of field, and astigmatism that are excessive in terms of aberration correction.
Therefore, the present application uses the aspheric lens component Ga and the aspheric lens component Gb as described above to achieve a zoom lens with a large angle of view that is small, corrects various aberrations well, and has high imaging performance. be able to.

Next, features of the zoom lens of the present application will be described based on the conditional expressions.
The conditional expression (1) is a conditional expression that defines the ratio of paraxial refractive powers of the aspheric lens component Ga and the aspheric lens component Gb in the front group. Note that the reason why all are described as “lens components” is because a so-called composite aspherical lens is taken into consideration. In the case of a composite aspherical lens made of a resin and a glass material, the resin portion cannot exist independently. Therefore, unlike a general cemented lens, it is appropriate to consider it as a single lens as a whole. Therefore, when calculating the corresponding value of the conditional expression (1) of the present application, when the aspheric lens component Ga or the aspheric lens component Gb is a composite aspheric lens, the resin portion and the glass lens portion are combined. The focal length of the axis shall be used.
The zoom lens of the present application has a relatively small paraxial focal length of the aspheric lens component Ga, that is, a large refractive power, and a relatively large paraxial focal length of the aspheric lens component Gb, that is, a small refractive power. Is a feature. The effect of this feature is that distortion, coma, field curvature, and astigmatism can be corrected well as described above, and the front lens diameter can be reduced.

When the corresponding value of the conditional expression (1) of the zoom lens of the present application exceeds the upper limit value, the absolute value of the paraxial focal length of the aspheric lens component Ga increases, that is, the paraxial negative refractive power decreases. In this case, the incident height of oblique rays increases, leading to an increase in the diameter of the front lens, which is not preferable. On the other hand, the paraxial focal length of the aspheric lens component Gb is small, that is, the paraxial refractive power is large. In this case, coma aberration, field curvature and astigmatism in the wide-angle end state, and coma aberration and spherical aberration in the telephoto end state are deteriorated, which is not preferable.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 0.625 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 0.600 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 0.550 or less, whereby coma aberration and the like can be corrected more favorably. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (1) to 0.300 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 0.200 or less. In order to maximize the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 0.100 or less.

On the other hand, when the corresponding value of the conditional expression (1) of the zoom lens of the present application is lower than the lower limit value, the aspheric lens component Ga has a positive refractive power. In this case, the incident height of oblique rays increases and the entire front group becomes enormous. Further, it is not preferable because coma aberration and field curvature in the wide-angle end state, and coma aberration, field curvature and astigmatism in the telephoto end state are deteriorated.
In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (1) to 0.005 or more, whereby various aberrations can be corrected more favorably. In order to maximize the effects of the present application, it is more preferable to set the lower limit of conditional expression (1) to 0.010 or more.

In addition, it is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 0.50 <(− Fn) / √ (Fw · Ft) <1.30
However,
Fn: Focal length of the front group when focusing on an object at infinity Fw: Focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state Ft: Said focal length when focusing on an object at infinity in the telephoto end state Focal length of the entire zoom lens system

Conditional expression (2) is a conditional expression related to the focal length of the front group. When the corresponding value of conditional expression (2) is 1.00, it means that the entire length of the zoom lens according to the present application matches in the wide-angle end state and the telephoto end state. Further, when the corresponding value of conditional expression (2) is smaller than 1.00, the total length is maximum in the telephoto end state, and when the corresponding value is larger than 1.00, the total length is maximum in the wide-angle end state. .
When the corresponding value of conditional expression (2) of the zoom lens of the present application exceeds the upper limit value, the absolute value of the focal length of the front group increases, that is, the negative refractive power of the front group decreases. As described above, the entire length of the zoom lens of the present application is maximized in the wide-angle end state. In this case, the incident height of oblique rays increases in the wide-angle end state, the front lens diameter and the filter diameter increase, and the peripheral light amount also decreases, which is not preferable. In addition, aberration correction is not preferable because coma variation due to zooming tends to increase.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.20 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.10 or less, whereby various aberrations can be corrected more favorably. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (2) to 1.05 or less. In order to maximize the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 1.02 or less.

On the other hand, when the corresponding value of conditional expression (2) of the zoom lens of the present application is below the lower limit value, the absolute value of the focal length of the front group is small, that is, the negative refractive power is large. Further, as described above, the entire length of the zoom lens of the present application is maximized in the telephoto end state. In this case, it becomes difficult to correct distortion aberration, coma aberration in the wide-angle end state, fluctuation due to zooming of the field curvature, and spherical aberration in the telephoto end state.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.60 or more, which is advantageous for correction of various aberrations such as coma. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (2) to 0.70 or more. In order to maximize the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.80 or more.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 1.50 <Fp / Fw <3.00
However,
Fp: Focal length of the rear group when focusing on an object at infinity Fw: Focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state

Conditional expression (3) is a conditional expression that defines the magnitude of the focal length of the rear group when the zoom lens of the present application is focused on an object at infinity, that is, the refractive power of the rear group.
If the corresponding value of conditional expression (3) of the zoom lens of the present application exceeds the upper limit value, it means that the focal length of the rear group is increased, that is, the refractive power of the rear group is decreased. In this case, the amount of movement of the rear group at the time of zooming increases and the overall length increases. Also, aberration correction is not preferable because the variation in field curvature due to zooming becomes large.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 2.90 or less. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (3) to 2.80 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 2.70 or less. In order to maximize the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 2.45 or less.

On the other hand, if the corresponding value of the conditional expression (3) of the zoom lens of the present application is below the lower limit value, it means that the focal length of the rear group is reduced, that is, the refractive power of the rear group is increased. In this case, the spherical aberration and the coma aberration are deteriorated, and fluctuations of the spherical aberration and the coma aberration due to the magnification change become large.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 1.70 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (3) to 1.80 or more, whereby various aberrations can be corrected more favorably. In order to secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (3) to 1.90 or more. In order to maximize the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 2.00 or more.

  In the zoom lens according to the present application, the front group includes the aspheric lens component Ga and the aspheric lens component Gb, and further includes at least a cemented negative lens component Gc of a negative lens and a positive lens. Is desirable. With this cemented negative lens component Gc, it is possible to perform better aberration correction, particularly correction of coma aberration, lateral chromatic aberration, and field curvature.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (4).
(4) 0.50 <(− Fc) / Fw <5.00
However,
Fc: focal length of the cemented negative lens component Gc in the front group Fw: focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state

Conditional expression (4) is a conditional expression that defines the magnitude of the focal length of the cemented negative lens component Gc in the front group, that is, the refractive power of the cemented negative lens component Gc.
When the corresponding value of conditional expression (4) of the zoom lens of the present application exceeds the upper limit value, the absolute value of the focal length of the cemented negative lens component Gc increases, that is, the negative refractive power of the cemented negative lens component Gc decreases. For this reason, the lateral chromatic aberration and the curvature of field, which have been sufficiently corrected, are deteriorated.
In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (4) to 4.00 or less. In order to further secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (4) to 3.00 or less, which makes it advantageous to correct various aberrations. In order to secure the effect of the present application, it is more preferable to set the upper limit value of conditional expression (4) to 2.80 or less. In order to maximize the effect of the present application, it is more preferable to set the upper limit of conditional expression (4) to 2.50 or less.

On the other hand, when the corresponding value of conditional expression (4) of the zoom lens of the present application is less than the lower limit value, the absolute value of the focal length of the cemented negative lens component Gc decreases, that is, the negative refractive power of the cemented negative lens component Gc increases. Become. For this reason, a change in chromatic aberration of magnification due to a difference in the angle of view and a residual in field curvature for each wavelength occur, which is not preferable.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 0.60 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (4) to 0.80 or more, whereby various aberrations can be corrected more favorably. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 1.00 or more. In order to maximize the effect of the present application, it is more preferable to set the lower limit of conditional expression (4) to 1.30 or more.

  In the zoom lens of the present application, the front group includes the aspheric lens component Ga and the aspheric lens component Gb, and further includes a negative lens component Gc of a negative lens and a positive lens, and the cemented lens. It is desirable to have a positive lens disposed on the image side of the negative lens component Gc. With this configuration, it is possible to satisfactorily correct distortion, field curvature, and coma in the wide-angle end state, and coma and spherical aberration in the telephoto end state.

Moreover, it is desirable that the zoom lens of the present application satisfies the following conditional expression (5).
(5) 0.00 <Ncn-Ncp
However,
Ncn: refractive index with respect to d-line (wavelength λ = 587.6 nm) of the negative lens medium in the cemented negative lens component Gc Ncp: d-line (wavelength λ) of the medium of the positive lens in the cemented negative lens component Gc = 587.6 nm)

Conditional expression (5) is a conditional expression that defines the difference in refractive index between the negative lens and the positive lens in the cemented negative lens component Gc. In the zoom lens of the present application, it is effective for aberration correction that the refractive index of the negative lens in the cemented negative lens component Gc is larger than the refractive index of the positive lens.
Therefore, when the corresponding value of conditional expression (5) of the zoom lens of the present application is below the lower limit value, the refractive index of the negative lens becomes relatively small. For this reason, it becomes difficult to optimally set the Petzval sum, and the field curvature and astigmatism are deteriorated.
In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to 0.05 or more. In order to further secure the effect of the present application, it is more preferable to set the lower limit value of conditional expression (5) to 0.10 or more, whereby various aberrations can be corrected more favorably. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to 0.15 or more. In order to maximize the effect of the present application, it is more preferable to set the lower limit of conditional expression (5) to 0.20 or more.

In the zoom lens of the present application, the aspheric lens component Ga in the front group is an aspheric surface having a radius of curvature that increases as the image-side surface moves toward the periphery, and the object-side surface moves toward the periphery. It is desirable that the aspherical surface has a shape with a radius of curvature that decreases with time. With this configuration, it is possible to satisfactorily correct distortion, field curvature, and coma particularly in the wide-angle end state.
In the zoom lens of the present application, it is desirable that the aspheric lens component Gb in the front group is composed of a compound lens made of glass and resin. With this configuration, the aspheric lens component Gb can be manufactured at low cost, and the glass material can be freely selected. As a result, it is preferable because better optical performance can be achieved.
Further, the imaging apparatus of the present application includes the zoom lens having the above-described configuration. As a result, it is possible to realize an imaging device with a large angle of view that is small, corrects various aberrations, and has high imaging performance.

The zoom lens manufacturing method of the present application is a zoom lens manufacturing method including a front group having a negative refractive power and a rear group having a positive refractive power in order from the object side. In order from the object side, the aspherical lens component Ga has a negative refracting power and a shape in which the negative refracting power decreases as it goes to the periphery, and has a positive refracting power and becomes negative as it goes to the periphery. An aspheric lens component Gb having a shape that turns or has a negative refractive power and a negative refractive power that increases toward the periphery, the aspheric lens component Ga and the aspheric lens component Gb, The following conditional expression (1) is satisfied, and zooming is performed by changing the air gap between the front group and the rear group.
(1) 0.000 ≦ (−Fa) / | Fb | <0.650
However,
Fa: Focal length of the aspheric lens component Ga in the front group Fb: Focal length of the aspheric lens component Gb in the front group By the method for manufacturing a zoom lens of the present application, the zoom lens is small and has various aberrations. A zoom lens having a large angle of view and high imaging performance can be manufactured.

Hereinafter, zoom lenses according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a configuration of a zoom lens according to Example 1 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a front group Gn having negative refractive power and a rear group Gp having positive refractive power.
The front group Gn includes, in order from the object side, an aspheric lens component Ga, an aspheric lens component Gb, a cemented negative lens component Gc, and a biconvex positive lens L15.
The aspheric lens component Ga has a negative refractive power and a shape in which the negative refractive power decreases as it goes toward the periphery, and includes a double-sided aspheric meniscus lens L11 with a concave surface facing the image side.
The aspherical lens component Gb has a composite positive aspherical power and a shape that changes to a negative refractive power toward the periphery, and is a composite aspherical positive lens formed by combining a resin portion and a glass lens. L12.
The cemented negative lens component Gc is composed of, in order from the object side, a cemented negative lens of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

The rear group Gp includes, in order from the object side, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, an aperture stop S, and a biconvex positive lens L23. A negative meniscus lens L24 having a concave surface facing the object side, a cemented positive lens of a biconcave negative lens L25 and a biconvex positive lens L26, a positive meniscus lens L27 having a convex surface facing the image side, and the image side It consists of a cemented positive lens with a negative meniscus lens L28 having a convex surface.
In the zoom lens according to the present embodiment, zooming from the wide-angle end state to the telephoto end state is performed by changing the air gap between the front group Gn and the rear group Gp. The arrows in FIG. 1 indicate the movement trajectories of the front group Gn and the rear group Gp during zooming from the wide-angle end state to the telephoto end state.

Table 1 below lists specifications of the zoom lens according to the present example.
In Table 1, F indicates the focal length and BF indicates the back focus.
In [Surface data], the surface number is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, nd is the refractive index with respect to the d-line (wavelength λ = 587.6 nm), νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm). Further, the object plane indicates the object plane, the variable indicates the variable plane spacing, the (aperture S) indicates the aperture stop S, and the image plane indicates the image plane I. The radius of curvature r = ∞ indicates a plane. Further, an asterisk “*” attached to the left side of the surface number indicates an aspherical surface.
[Aspherical data] shows the conical coefficient and aspherical coefficient when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
X (y) = (y ² / r) / [1+ {1-κ (y ² / r ² )} ^1/2 ]
+ A4 × y ⁴ + A6 × y ⁶ + A8 × y ⁸ + A10 × y ¹⁰ + A12 × y ¹²
Here, the height in the direction perpendicular to the optical axis is y, the amount of displacement in the optical axis direction at height y is X (y), the radius of curvature of the reference sphere (paraxial radius of curvature) is r, the cone coefficient is κ, Let the n-th order aspheric coefficient be An. “En” represents “× 10 ⁻ⁿ ”, for example “1.234E-05” represents “1.234 × 10 ⁻⁵ ”.

In [Various data], FNO is the F number, ω is the half angle of view (unit: degree), Y is the image height, TL is the total length of the optical system, and Σd is the most object side lens surface (first surface). , D0 is a distance from the object surface to the first surface, and di (i: integer) is a variable surface interval of the i-th surface. 1-POS indicates when an object at infinity is in focus at the wide-angle end state, 2-POS indicates when the object at infinity is in focus at the intermediate focal length state, and 3-POS indicates when the object at infinity is in focus at the telephoto end state. .
Here, the focal length F, the radius of curvature r, and other length units listed in Table 1 are generally “mm”. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1) 120.0323 3.0000 1.744430 49.53
* 2) 14.8111 11.0000 1.000000
3) 320.0965 3.0000 1.516800 64.12
4) 70.0000 1.0000 1.553890 38.09
* 5) -993.8663 4.5000 1.000000
6) -56.5907 2.0000 1.816000 46.63
7) 17.0196 7.0000 1.603420 38.02
8) 73.8459 0.1000 1.000000
9) 32.4760 5.0000 1.717360 29.52
10) -157.9244 Variable 1.000000
11) 23.8096 1.0000 1.795000 45.30
12) 15.6593 3.0000 1.497820 82.56
13) -1090.6220 6.0000 1.000000
14) (Aperture S) ∞ 0.7000 1.000000
15) 26.3980 2.5000 1.497820 82.56
16) -79.3224 4.6000 1.000000
17) -39.5467 8.0000 1.744000 44.79
18) -162.0229 2.0000 1.000000
19) -92.3426 1.0000 1.755000 52.29
20) 20.8016 5.0000 1.518230 58.89
21) -21.0542 0.1000 1.000000
22) -344.4872 5.5000 1.497820 82.56
23) -13.5094 1.0000 1.834810 42.72
24) -31.7192 BF 1.000000
Image plane ∞

[Aspherical data]
First side κ = 12.7063
A4 = 2.52869E-07
A6 = 5.51300E-10
A8 = 4.77913E-13
A10 = -3.07832E-16
A12 = -0.49549E-19
Second surface κ = -0.0947
A4 = -6.70196E-06
A6 = -1.78783E-08
A8 = -5.15142E-12
A10 = -4.83366E-14
A12 = 0.21367E-15
Fifth surface κ = 0.000
A4 = 2.50710E-05
A6 = 2.09871E-08
A8 = 1.63612E-10
A10 = -1.20936E-13
A12 = -0.17594E-14

[Various data]
Zoom ratio 1.77

1-POS 2-POS 3-POS
F 16.48-24.00-29.10
FNO 4.41-5.29-5.88
ω 53.27 to 41.72 to 36.32 °
Y 21.60-21.60-21.60
TL 138.15-135.51-138.24
Σd 99.84 to 84.47 to 78.57
BF 38.31 to 51.04 to 59.67

1-POS 2-POS 3-POS
F 16.48000 24.00000 29.10000
d0 ∞ ∞ ∞
d10 22.83854 7.47382 1.57260
BF 38.31325 51.03766 59.66724

[Lens group data]
Group start surface F
Gn 1 -21.85385
Gp 11 36.97834

[Conditional expression values]
(1) (−Fa) /|Fb|=0.0620
(2) (−Fn) / √ (Fw · Ft) = 0.998
(3) Fp / Fw = 2.243
(4) (−Fc) /Fw=1.636
(5) Ncn-Ncp = 0.2126

2 (a), 2 (b), and 2 (c) respectively show various aberrations and intermediate focal length states at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 1 of the present application. It is a figure which shows the various aberrations at the time of focusing on an object at infinity and various aberrations at the time of focusing on an object at infinity in the telephoto end state.
In each aberration diagram, FNO is an F number, Y is an image height, d is a d-line (λ = 587.6 nm), and g is a g-line (λ = 435.8 nm). The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, and the astigmatism diagram and the distortion diagram show the maximum image height. In the astigmatism diagram, the solid line indicates the sagittal image plane, the dotted line indicates the meridional image plane, and the solid line in the coma aberration diagram indicates the meridional coma aberration. Note that the same reference numerals as in this example are also used in the aberration diagrams of the examples shown below.
From the various aberration diagrams, it can be seen that the zoom lens according to the present example is well corrected for various aberrations including spherical aberration, field curvature, astigmatism, and coma.

(Second embodiment)
FIG. 3 is a cross-sectional view showing a configuration of a zoom lens according to Example 2 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a front group Gn having negative refractive power and a rear group Gp having positive refractive power.
The front group Gn includes, in order from the object side, an aspheric lens component Ga, an aspheric lens component Gb, a cemented negative lens component Gc, and a biconvex positive lens L15.
The aspheric lens component Ga has a negative refractive power and a shape in which the negative refractive power decreases as it goes toward the periphery, and includes a double-sided aspheric meniscus lens L11 with a concave surface facing the image side.
The aspherical lens component Gb has a composite positive aspherical power and a shape that changes to a negative refractive power toward the periphery, and is a composite aspherical positive lens formed by combining a resin portion and a glass lens. L12.
The cemented negative lens component Gc is composed of, in order from the object side, a cemented negative lens of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

The rear group Gp includes, in order from the object side, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, an aperture stop S, and a biconvex positive lens L23. A biconcave negative lens L24, a cemented positive lens formed by cementing a biconcave negative lens L25 and a biconvex positive lens L26, and a biconcave positive lens L27 and a convex surface facing the image side. It consists of a cemented negative lens with a negative meniscus lens L28.
In the zoom lens according to the present embodiment, zooming from the wide-angle end state to the telephoto end state is performed by changing the air gap between the front group Gn and the rear group Gp. Note that the arrows in FIG. 3 indicate the movement trajectories of the front group Gn and the rear group Gp during zooming from the wide-angle end state to the telephoto end state.
Table 2 below shows specification values of the zoom lens according to the present example.

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1) 82.7358 3.0000 1.744429 49.52
* 2) 14.1379 9.0000 1.000000
3) 75.5790 3.0000 1.516800 64.12
4) 40.0000 0.5000 1.553890 38.09
* 5) 83.8029 6.0000 1.000000
6) -77.5324 2.0000 1.816000 46.63
7) 17.4612 6.5000 1.603420 38.02
8) 70.9358 1.0500 1.000000
9) 34.6649 5.0000 1.717360 29.52
10) -214.0325 Variable 1.000000
11) 27.4177 1.0000 1.788000 47.38
12) 15.1887 3.0000 1.497820 82.56
13) -218.1559 6.0000 1.000000
14) (Aperture S) ∞ 0.7000 1.000000
15) 23.2434 2.8000 1.487490 70.45
16) -45.2239 4.6270 1.000000
17) -39.0084 8.0000 1.755000 52.29
18) 114.1192 2.0000 1.000000
19) -94.3568 1.0000 1.755000 52.29
20) 26.8051 5.0000 1.518230 58.89
21) -18.1493 0.1000 1.000000
22) 471.7364 5.5000 1.497820 82.56
23) -12.7396 1.0000 1.834810 42.72
24) -33.4851 BF 1.000000
Image plane ∞

[Aspherical data]
First side κ = 4.0103
A4 = 1.16908E-06
A6 = 4.58987E-10
A8 = 4.52741E-14
A10 = -7.38248E-16
A12 = 0.0000

Second surface κ = -0.0638
A4 = -7.94597E-07
A6 = -5.98169E-09
A8 = 2.11786E-11
A10 = -5.51429E-14
A12 = 0.81892E-16
Fifth surface κ = -5.6064
A4 = 2.51241E-05
A6 = 2.20702E-08
A8 = 5.50134E-11
A10 = -1.42359E-13
A12 = -0.72010E-15

[Various data]
Zoom ratio 1.77

1-POS 2-POS 3-POS
F 16.48-24.00-29.10
FNO 4.40-5.27-5.87
ω 53.20 to 41.29 to 35.96 °
Y 21.60-21.60-21.60
TL 137.91-135.13-137.77
Σd 99.61-84.25-78.35
BF 38.29-50.88-59.41

1-POS 2-POS 3-POS
F 16.48028 24.00000 29.10000
d0 ∞ ∞ ∞
d10 22.83788 7.47624 1.57589
BF 38.29222 50.87810 59.41406

[Lens group data]
Group start surface F
Gn 1 -21.97176
Gp 11 36.77451

[Conditional expression values]
(1) (−Fa) /|Fb|=0.0292
(2) (−Fn) / √ (Fw · Ft) = 1.003
(3) Fp / Fw = 2.232
(4) (−Fc) /Fw=1.883
(5) Ncn-Ncp = 0.2126

4 (a), 4 (b), and 4 (c) respectively show various aberrations and intermediate focal length states at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 2 of the present application. It is a figure which shows the various aberrations at the time of focusing on an object at infinity and various aberrations at the time of focusing on an object at infinity in the telephoto end state.
From the various aberration diagrams, it can be seen that the zoom lens according to the present example is well corrected for various aberrations including spherical aberration, field curvature, astigmatism, and coma.

(Third embodiment)
FIG. 5 is a cross-sectional view showing a configuration of a zoom lens according to Example 3 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a front group Gn having negative refractive power and a rear group Gp having positive refractive power.
The front group Gn includes, in order from the object side, an aspheric lens component Ga, an aspheric lens component Gb, a cemented negative lens component Gc, and a biconvex positive lens L15.
The aspheric lens component Ga has a negative refractive power and a shape in which the negative refractive power decreases as it goes toward the periphery, and includes a double-sided aspheric meniscus lens L11 with a concave surface facing the image side.
The aspherical lens component Gb has a composite positive aspherical power and a shape that changes to a negative refractive power toward the periphery, and is a composite aspherical positive lens formed by combining a resin portion and a glass lens. L12.
The cemented negative lens component Gc is composed of, in order from the object side, a cemented negative lens of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

The rear group Gp includes, in order from the object side, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, an aperture stop S, and a biconvex positive lens L23. A negative meniscus lens L24 having a concave surface facing the object side, a cemented positive lens of a biconcave negative lens L25 and a biconvex positive lens L26, a positive meniscus lens L27 having a convex surface facing the image side, and the image side It consists of a cemented positive lens with a negative meniscus lens L28 having a convex surface.
In the zoom lens according to the present embodiment, zooming from the wide-angle end state to the telephoto end state is performed by changing the air gap between the front group Gn and the rear group Gp. Note that the arrows in FIG. 5 indicate the movement trajectories of the front group Gn and the rear group Gp during zooming from the wide-angle end state to the telephoto end state.
Table 3 below shows specification values of the zoom lens according to the present example.

(Table 3) Third Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1) 118.9748 3.0000 1.744429 49.52
* 2) 14.7456 11.0000 1.000000
3) 284.3220 3.0000 1.516800 64.12
4) 70.0000 1.0000 1.553890 38.09
* 5) -763.4452 4.5000 1.000000
6) -55.5066 2.0000 1.816000 46.63
7) 17.0766 7.0000 1.603420 38.02
8) 75.0652 0.1000 1.000000
9) 32.6574 5.0000 1.717360 29.52
10) -157.9244 Variable 1.000000
11) 23.8427 1.0000 1.795000 45.30
12) 15.6582 3.0000 1.497820 82.56
13) -1090.6220 6.0000 1.000000
14) (Aperture S) ∞ 0.7000 1.000000
15) 26.3772 2.5000 1.497820 82.56
16) -77.6232 4.6000 1.000000
17) -39.5697 8.0000 1.744000 44.79
18) -168.4305 2.0000 1.000000
19) -92.1532 1.0000 1.755000 52.29
20) 20.6673 5.0000 1.518230 58.89
21) -21.0064 0.1000 1.000000
22) -353.1908 5.5000 1.497820 82.56
23) -13.5255 1.0000 1.834810 42.72
24) -31.7192 BF 1.000000
Image plane ∞

[Aspherical data]
First surface κ = 12.7326
A4 = 2.83606E-07
A6 = 4.94742E-10
A8 = 4.56144E-13
A10 = -3.11089E-16
A12 = 0.14795E-19
Second surface κ = -0.0904
A4 = -6.75619E-06
A6 = -1.80695E-08
A8 = -4.67950E-12
A10 = -4.79969E-14
A12 = 0.21420E-15
Fifth surface κ = 0.000
A4 = 2.50236E-05
A6 = 2.14959E-08
A8 = 1.65356E-10
A10 = -1.19372E-13
A12 = -0.17563E-14

[Various data]
Zoom ratio 1.77

1-POS 2-POS 3-POS
F 16.48-24.00-29.10
FNO 4.41-5.29-5.88
ω 53.17 to 41.64 to 36.27 °
Y 21.60-21.60-21.60
TL 138.13-135.48-138.21
Σd 99.84 to 84.47 to 78.57
BF 38.29-51.01-59.64

1-POS 2-POS 3-POS
F 16.48000 24.00000 29.10000
d0 ∞ ∞ ∞
d10 22.83880 7.47127 1.56898
BF 38.29336 51.01228 59.63815

[Lens group data]
Group start surface F
Gn 1 -21.86055
Gp 11 36.97375

[Conditional expression values]
(1) (−Fa) /|Fb|=0.0702
(2) (−Fn) / √ (Fw · Ft) = 0.998
(3) Fp / Fw = 2.244
(4) (−Fc) /Fw=1.663
(5) Ncn-Ncp = 0.2126

6 (a), 6 (b), and 6 (c) respectively show various aberrations and intermediate focal length states at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 3 of the present application. It is a figure which shows the various aberrations at the time of focusing on an object at infinity and various aberrations at the time of focusing on an object at infinity in the telephoto end state.
From the various aberration diagrams, it can be seen that the zoom lens according to the present example is well corrected for various aberrations including spherical aberration, field curvature, astigmatism, and coma.

(Fourth embodiment)
FIG. 7 is a sectional view showing the structure of a zoom lens according to Example 4 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a front group Gn having negative refractive power and a rear group Gp having positive refractive power.
The front group Gn includes, in order from the object side, an aspheric lens component Ga, an aspheric lens component Gb, a cemented negative lens component Gc, and a biconvex positive lens L15.
The aspheric lens component Ga has a negative refractive power and a shape in which the negative refractive power decreases as it goes toward the periphery, and includes a double-sided aspheric meniscus lens L11 with a concave surface facing the image side.
The aspheric lens component Gb includes an aspheric negative meniscus lens L12 having a negative refractive power and a shape in which the negative refractive power increases toward the periphery.
The cemented negative lens component Gc is composed of, in order from the object side, a cemented negative lens of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.

The rear group Gp includes a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. L23, aperture stop S, biconvex positive lens L24, negative meniscus lens L25 having a concave surface facing the object side, biconcave negative lens L26, and biconvex positive lens L27 are cemented together. And a cemented negative lens of a positive meniscus lens L28 having a convex surface facing the image side and a negative meniscus lens L29 having a convex surface facing the image side.
In the zoom lens according to the present embodiment, zooming from the wide-angle end state to the telephoto end state is performed by changing the air gap between the front group Gn and the rear group Gp. 7 indicate the movement trajectories of the front group Gn and the rear group Gp during zooming from the wide-angle end state to the telephoto end state.
Table 4 below shows specification values of the zoom lens according to the present example.

(Table 4) Fourth Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1) 143.1913 3.0000 1.744430 49.53
* 2) 15.6782 11.0000 1.000000
3) 410.4013 3.0000 1.713000 53.89
* 4) 206.9456 4.5000 1.000000
5) -89.1834 2.0000 1.816000 46.63
6) 15.1616 7.5000 1.603420 38.02
7) 40.8243 0.1000 1.000000
8) 26.8914 5.5000 1.717360 29.52
9) -157.9244 Variable 1.000000
10) 46.8881 1.0000 1.804000 46.58
11) 16.8336 2.5000 1.516800 64.12
12) 141.4373 0.1000 1.000000
13) 25.7582 2.5000 1.497820 82.56
14) 353.5585 6.0000 1.000000
15) (Aperture S) ∞ 0.7000 1.000000
16) 29.4255 2.5000 1.497820 82.56
17) -63.3534 4.6000 1.000000
18) -51.5779 8.0000 1.744000 44.79
19) -65.0596 2.0000 1.000000
20) -78.0641 1.0000 1.755000 52.29
21) 17.7780 5.0000 1.518230 58.89
22) -21.4040 0.1000 1.000000
23) -67.9060 5.5000 1.497820 82.56
24) -12.6974 1.0000 1.834810 42.72
25) -31.7192 BF 1.000000
Image plane ∞

[Aspherical data]
First side κ = 17.6085
A4 = 1.79431E-06
A6 = 6.80079E-10
A8 = -1.86415E-13
A10 = -8.67549E-16
A12 = 0.16129E-17

Second surface κ = -0.2161
A4 = -7.04903E-06
A6 = -1.23127E-08
A8 = -1.85973E-11
A10 = -5.29912E-14
A12 = 0.27950E-15
4th surface κ = 0.000
A4 = 2.47716E-05
A6 = 2.95962E-08
A8 = 1.29703E-10
A10 = -1.58560E-13
A12 = -0.20420E-14

[Various data]
Zoom ratio 1.88

1-POS 2-POS 3-POS
F 16.48 to 24.92 to 31.01
FNO 4.32 to 5.19 to 5.86
ω 52.87 to 40.72 to 34.68 °
Y 21.60-21.60-21.60
TL 140.236-139.54-144.237
Σd 101.939 to 86.57 to 80.673
BF 38.297-52.964-63.565

1-POS 2-POS 3-POS
F 16.48254 24.91831 31.01490
d0 ∞ ∞ ∞
d9 22.83854 7.47382 1.57260
BF 38.29718 52.96439 63.56450

[Lens group data]
Group start surface F
Gn 1 -20.74244
Gp 10 36.06477

[Conditional expression values]
(1) (−Fa) /|Fb|=0.0406
(2) (-Fn) / √ (Fw · Ft) = 0.884
(3) Fp / Fw = 2.188
(4) (−Fc) /Fw=1.5222
(5) Ncn-Ncp = 0.2126

FIGS. 8A, 8B, and 8C are graphs showing various aberrations and intermediate focal length states at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 4 of the present application, respectively. It is a figure which shows the various aberrations at the time of focusing on an object at infinity and various aberrations at the time of focusing on an object at infinity in the telephoto end state.
From the various aberration diagrams, it can be seen that the zoom lens according to the present example is well corrected for various aberrations including spherical aberration, field curvature, astigmatism, and coma.

(5th Example)
FIG. 9 is a sectional view showing the structure of a zoom lens according to Example 5 of the present application.
The zoom lens according to the present embodiment includes, in order from the object side, a front group Gn having a negative refractive power, a rear group Gp having a positive refractive power, and a fixed group Gs.
The front group Gn includes, in order from the object side, an aspheric lens component Ga, an aspheric lens component Gb, a cemented negative lens component Gc, and a biconvex positive lens L15.
The aspheric lens component Ga has a negative refracting power and a shape in which the negative refracting power decreases as it goes to the periphery, and is composed of a double-sided aspheric meniscus lens L11 having a concave surface facing the image side.
The aspherical lens component Gb has a shape that has a positive refracting power and turns to a negative refracting power toward the periphery, and is a composite aspherical positive lens L12 formed by combining a resin portion and a glass lens. Consists of.
The cemented negative lens component Gc is composed of, in order from the object side, a cemented negative lens of a biconcave negative lens L13 and a positive meniscus lens L14 having a convex surface facing the object side.
The rear group Gp includes, in order from the object side, a cemented positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, an aperture stop S, and a biconvex positive lens L23. A negative meniscus lens L24 having a concave surface facing the object side, a cemented positive lens of a biconcave negative lens L25 and a biconvex positive lens L26, a positive meniscus lens L27 having a convex surface facing the image side, and the image side It consists of a cemented positive lens with a negative meniscus lens L28 having a convex surface.
The fixed group Gs includes only a negative meniscus lens L31 having a convex surface facing the image side.
In the zoom lens according to the present embodiment, zooming from the wide-angle end state to the telephoto end state is performed by changing the air gap between the front group Gn and the rear group Gp. Note that the position of the fixed group Gs is fixed during zooming. Further, the arrows in FIG. 9 indicate the movement trajectories of the front group Gn and the rear group Gp during zooming from the wide-angle end state to the telephoto end state.
Table 5 below shows specification values of the zoom lens according to the present example.

(Table 5) Fifth Example
[Surface data]
Surface number r d nd νd
Object ∞
* 1) 120.0323 3.0000 1.744430 49.53
* 2) 14.8111 11.0000 1.000000
3) 320.0965 3.0000 1.516800 64.12
4) 70.0000 1.0000 1.553890 38.09
* 5) -993.8663 4.5000 1.000000
6) -56.5907 2.0000 1.816000 46.63
7) 17.0196 7.0000 1.603420 38.02
8) 73.8459 0.1000 1.000000
9) 32.4760 5.0000 1.717360 29.52
10) -157.9244 Variable 1.000000
11) 23.8096 1.0000 1.795000 45.30
12) 15.6593 3.0000 1.497820 82.56
13) -1090.6220 5.9435 1.000000
14) (Aperture S) ∞ 0.7000 1.000000
15) 26.3980 2.5000 1.497820 82.56
16) -79.3224 4.6000 1.000000
17) -39.5467 8.0000 1.744000 44.79
18) -162.0229 2.0000 1.000000
19) -92.3426 1.0000 1.755000 52.29
20) 20.8016 5.0000 1.518230 58.89
21) -21.0542 0.1000 1.000000
22) -344.4872 5.5000 1.497820 82.56
23) -13.5094 1.0000 1.834810 42.72
24) -31.7192 Variable 1.000000
25) -100.0000 2.0000 1.516800 64.12
26) -107.0000 BF 1.000000
Image plane ∞

[Aspherical data]
First side κ = 12.7063
A4 = 2.52869E-07
A6 = 5.51300E-10
A8 = 4.77913E-13
A10 = -3.07832E-16
A12 = -0.49549E-19
Second surface κ = -0.0947
A4 = -6.70196E-06
A6 = -1.78783E-08
A8 = -5.15142E-12
A10 = -4.83366E-14
A12 = 0.21367E-15
Fifth surface κ = 0.000
A4 = 2.50710E-05
A6 = 2.09871E-08
A8 = 1.63612E-10
A10 = -1.20936E-13
A12 = -0.17594E-14

[Various data]
Zoom ratio 1.77

1-POS 2-POS 3-POS
F 16.48-24.00-29.10
FNO 4.49-5.33-5.93
ω 52.73 to 41.73 to 36.33 °
Y 21.60-21.60-21.60
TL 139.69-136.93-139.40
Σd 102.78 to 100.03 to 102.50
BF 36.90-36.90-36.90

1-POS 2-POS 3-POS
F 16.48000 24.00000 29.10000
d0 ∞ ∞ ∞
d10 22.83854 8.08582 2.08111
d24 1.00000 12.99953 21.47140
BF 36.90477 36.90477 36.90477

[Lens group data]
Group start surface F
Gn 1 -21.85385
Gp 11 36.95878
Gs 25 -3276.74607

[Conditional expression values]
(1) (−Fa) /|Fb|=0.0620
(2) (−Fn) / √ (Fw · Ft) = 0.998
(3) Fp / Fw = 2.243
(4) (−Fc) /Fw=1.636
(5) Ncn-Ncp = 0.2126

10 (a), 10 (b), and 10 (c) respectively show various aberrations and intermediate focal length states at the time of focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 5 of the present application. It is a figure which shows the various aberrations at the time of focusing on an object at infinity and various aberrations at the time of focusing on an object at infinity in the telephoto end state.
From the various aberration diagrams, it can be seen that the zoom lens according to the present example is well corrected for various aberrations including spherical aberration, field curvature, astigmatism, and coma.

According to each of the above embodiments, the wide angle end state is suitable for an imaging device such as a single-lens reflex camera, and the inclusive angle exceeds 2ω = 106.3 °, and the aperture number is about F-number = 4 to 5.6. A retrofocus zoom lens having a small number of lenses, a small front lens diameter, that is, a small filter diameter, a small size, excellent correction of various aberrations, and high imaging performance can be realized.
Here, each said Example has shown one specific example of this invention, and this invention is not limited to these. The following contents can be appropriately adopted within a range that does not impair the optical performance of the zoom lens of the present application.
As a numerical example of the zoom lens of the present application, a two-group and three-group configuration is shown, but the present application is not limited to this, and a zoom lens having other group configurations (for example, four groups, five groups, etc.) should be configured. You can also. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image side of the zoom lens of the present application may be used. The lens group means a portion having at least one lens separated by an air space.

In addition, the zoom lens of the present application is used in order to focus from an object at infinity to an object at a short distance in the direction of the optical axis using a part of the lens group, the entire lens group, or a plurality of lens groups as the focusing lens group. It is good also as a structure moved to. The focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor. In particular, in the zoom lens of the present application, it is preferable that at least a part of the front group or the rear group is a focusing lens group.
Also, in the zoom lens of the present application, either all or a part of any lens group is moved so as to include a component in a direction orthogonal to the optical axis as an anti-vibration lens group, or rotated in an in-plane direction including the optical axis. It can also be configured to correct image blur caused by camera shake by moving (swinging). In particular, in the zoom lens of the present application, it is preferable that at least a part of the rear group is an anti-vibration lens group.

The lens surface of the lens constituting the zoom lens of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.
In the zoom lens of the present application, it is preferable that the aperture stop is disposed in or near the rear group, and the role may be substituted by a lens frame without providing a member as the aperture stop.

Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom lens of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.
The zoom lens of the present application has a zoom ratio of about 2 to 7.
In the zoom lens of the present application, it is preferable that the front group has two positive lens components and two negative lens components. In particular, these lens components are in order of negative, positive, negative, and positive in order from the object side. It is preferable to arrange them at intervals. Alternatively, the front group preferably has one positive lens component and three negative lens components, and in particular, these lens components are arranged in order of negative, negative, negative, and positive in this order from the object side. It is preferable to do. The rear group preferably has three positive lens components and one negative lens component. In particular, these lens components are arranged in order of positive, positive, negative, and positive in order from the object side. It is preferable to arrange.

Next, a camera equipped with the zoom lens of the present application will be described with reference to FIG.
FIG. 11 is a diagram illustrating a configuration of a camera including the zoom lens of the present application.
The camera 1 is a digital single-lens reflex camera provided with the zoom lens according to the first embodiment as a photographing lens 2.
In the camera 1, light from an object (subject) (not shown) is collected by the taking lens 2 and imaged on the focusing screen 4 through the quick return mirror 3. The light imaged on the focusing screen 4 is reflected in the pentaprism 5 a plurality of times and guided to the eyepiece lens 6. Thus, the photographer can observe the subject image as an erect image through the eyepiece 6.

When the release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and light from the subject (not shown) reaches the image sensor 7. Thereby, the light from the subject is picked up by the image pickup device 7 and recorded as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.
Here, the zoom lens according to the first embodiment mounted on the camera 1 as the photographing lens 2 is small in size, has a small number of lenses, corrects various aberrations, and has high results due to its characteristic lens configuration. Has image performance and large angle of view. As a result, the camera 1 is small, corrects various aberrations well, has high imaging performance, and can perform wide-angle imaging including a large angle of view. Even if the camera having the zoom lens according to the second to fifth embodiments mounted as the taking lens 2 is configured, the same effect as the camera 1 can be obtained.

Finally, the outline of the manufacturing method of the zoom lens of this application is demonstrated based on FIG.
The zoom lens manufacturing method of the present application is a zoom lens manufacturing method including a front group having negative refractive power and a rear group having positive refractive power in order from the object side, and includes the following steps S1 to S3. Is included.
Step S1: In order from the object side, the front group has an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power becomes smaller toward the periphery, and has a positive refracting power toward the periphery. The aspherical lens component Gb has a shape that changes to negative refractive power as it goes or a shape that has negative refractive power and increases toward the periphery.

Step S2: Arrange the front group and the rear group in order from the object side in the lens barrel so that the aspheric lens component Ga and the aspheric lens component Gb satisfy the following conditional expression (1).
(1) 0.000 ≦ (−Fa) / | Fb | <0.650
However,
Fa: Focal length of the aspheric lens component Ga in the front group Fb: Focal length of the aspheric lens component Gb in the front group Step S3: Changing an air interval between the front group and the rear group. To change the magnification.
According to the zoom lens manufacturing method of the present application, it is possible to manufacture a zoom lens having a large angle of view that is small in size, corrects various aberrations favorably, and has high imaging performance.

Gn Front group Gp Rear group Ga Aspheric lens component Gb Aspheric lens component Gc Joint negative lens component S Aperture stop I Image surface

Claims (12)

In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspheric lens component Gb having a shape that shifts to the refractive power of the lens or a shape that has a negative refractive power and the negative refractive power increases toward the periphery,
Performing zooming by changing the air spacing between the front group and the rear group,
A zoom lens satisfying the following conditional expression:
0.0406 ≦ (−Fa) / | Fb | < 0.600
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a negative refractive power or a shape having a negative refractive power and a negative refractive power increasing toward the periphery, and a cemented negative lens of a negative lens and a positive lens Having at least component Gc,
Performing zooming by changing the air spacing between the front group and the rear group,
A zoom lens satisfying the following conditional expression:
0.000 < (-Fa) / | Fb | <0.650
0.50 <(− Fc) /Fw≦1.883
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group
Fc: focal length of the cemented negative lens component Gc in the front group
Fw: focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state In order from the object side, it has a front group having negative refractive power and a rear group having positive refractive power,
The front group includes, in order from the object side, an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a negative refractive power or a shape having a negative refractive power and a negative refractive power increasing toward the periphery, and a cemented negative lens of a negative lens and a positive lens A component Gc, and a positive lens disposed on the image side of the cemented negative lens component Gc,
Performing zooming by changing the air spacing between the front group and the rear group,
A zoom lens satisfying the following conditional expression:
0.000 < (-Fa) / | Fb | < 0.600
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group The front group includes the aspheric lens component Ga and the aspheric lens component Gb, and further includes at least a cemented negative lens component Gc of a negative lens and a positive lens.
The zoom lens according to claim 1 or 3, characterized by satisfying the following conditional expression.
0.50 <(− Fc) / Fw <5.00
However,
Fc: focal length of the cemented negative lens component Gc in the front group Fw: focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state The front group includes the aspheric lens component Ga and the aspheric lens component Gb, and further includes a cemented negative lens component Gc of a negative lens and a positive lens, and an image side of the cemented negative lens component Gc. the zoom lens according to claim 1 or 2, characterized in that it has a deployed positive lens. The zoom lens according to any one of claims 2 to 5, wherein the following conditional expression is satisfied.
0.00 <Ncn-Ncp
However,
Ncn: refractive index with respect to d-line (wavelength λ = 587.6 nm) of the negative lens medium in the cemented negative lens component Gc Ncp: d-line (wavelength λ) of the medium of the positive lens in the cemented negative lens component Gc = 587.6 nm) The zoom lens according to any one of claims 1 to 6 , wherein the following conditional expression is satisfied.
0.50 <(− Fn) / √ (Fw · Ft) <1.30
However,
Fn: Focal length of the front group when focusing on an object at infinity Fw: Focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state Ft: Said focal length when focusing on an object at infinity in the telephoto end state Focal length of the entire zoom lens system The zoom lens according to any one of claims 1 7, characterized by satisfying the following conditional expression.
1.50 <Fp / Fw <3.00
However,
Fp: Focal length of the rear group when focusing on an object at infinity Fw: Focal length of the entire zoom lens system when focusing on an object at infinity in the wide-angle end state The aspheric lens component Ga in the front group is an aspheric surface having a curvature that increases as the object-side surface moves toward the periphery, and an aspheric surface that decreases in curvature as the image-side surface moves toward the periphery. the zoom lens according to any one of claims 1 to 8, characterized in that. Wherein the aspherical lens component Gb in the previous group, the zoom lens according to any one of claims 1 to 9, characterized in that it is a composite lens of glass and resin. Imaging apparatus characterized by comprising a zoom lens according to any one of claims 1 to 10. In order from the object side, a zoom lens having a front group having negative refractive power and a rear group having positive refractive power,
In order from the object side, the front group has an aspheric lens component Ga having a negative refracting power and a shape in which the negative refracting power decreases as it goes toward the periphery, and has a positive refracting power and becomes negative as it goes toward the periphery. An aspherical lens component Gb having a shape that shifts to the refractive power of the lens or a shape that has a negative refractive power and the negative refractive power increases toward the periphery,
The aspheric lens component Ga and the aspheric lens component Gb satisfy the following conditional expression:
A zoom lens manufacturing method, wherein zooming is performed by changing an air gap between the front group and the rear group.
0.0406 ≦ (−Fa) / | Fb | < 0.600
However,
Fa: focal length of the aspheric lens component Ga in the front group Fb: focal length of the aspheric lens component Gb in the front group

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