WO2013125603A1

WO2013125603A1 - Zoom lens, imaging device, and portable terminal

Info

Publication number: WO2013125603A1
Application number: PCT/JP2013/054236
Authority: WO
Inventors: 尾崎雄一
Original assignee: コニカミノルタ株式会社
Priority date: 2012-02-20
Filing date: 2013-02-20
Publication date: 2013-08-29
Also published as: JPWO2013125603A1

Abstract

The objective is to provide a zoom lens that achieves compactness in the thickness direction and satisfactorily corrects various aberrations, an imaging device using the lens, and a portable terminal. A zoom lens (10) forms an image of the subject on the imaging plane (I) of an imaging element (51), and is composed of a positive first lens group (Gr1), a negative second lens group (Gr2), a positive third lens group (Gr3), a negative fourth lens group (Gr4), and a positive fifth lens group (Gr5) in order from the object side. When there is variable magnification from the wide-angle end to the telephoto end, the first and fifth lens groups (Gr1, Gr5) are fixed, and the second lens group (Gr2) moves to the image side. This zoom lens (10) satisfies the condition equation 0.8 < f3/fW < 1.4 (1) where f3 is the focal length of the third lens group (Gr3), and fW is the focal length of the entire zoom lens (10) system at the wide-angle end.

Description

Zoom lens, imaging device, and portable terminal

The present invention relates to a zoom lens that includes a plurality of lens groups and performs zooming by changing an interval between the lens groups in the optical axis direction, an imaging device including the zoom lens, and a portable terminal including the imaging device.

In recent years, with the improvement in performance and size of solid-state imaging devices such as CCD (Charge-Coupled Device) -type image sensors or CMOS (Complementary-Metal-Oxide-Semiconductor) -type image sensors, mobile phones equipped with imaging devices, etc. Mobile terminals are popular. Since these devices are extremely limited in size and cost, they have a small solid-state image sensor with a small number of pixels compared to ordinary digital still cameras, etc., and single-focus optics consisting of about 1 to 4 plastic lenses. An imaging apparatus including a system is generally used. However, imaging devices mounted on mobile terminals are also rapidly increasing in pixel count and functionality, can handle high pixel imaging devices, and can shoot subjects far away from the photographer with a long focal length. A small zoom lens that can be mounted on a mobile terminal such as a mobile phone to enable shooting over a wide range with a short focal length when the distance from the subject cannot be separated as in indoor shooting. Is required.

In order to mount a zoom lens on a mobile terminal such as a mobile phone, it is required to reduce the thickness especially in the thickness direction among the miniaturization.

In such a thin zoom lens, a bending optical system that bends the optical axis by 90 degrees using a reflecting optical element such as a prism is often used, and the reflecting optical element is used for the first lens group. A variable power optical system that is downsized in the thickness direction is known (see Patent Documents 1 to 3).

In general, the imaging surface (effective pixel area) of a solid-state imaging device used in an imaging apparatus is often a rectangular shape of 4: 3 or 16: 9, and in a lens relatively close to the solid-state imaging device. The range through which the imaging light bundle passes (optical use range) is often a shape close to a rectangle like the imaging surface of the solid-state imaging device. Therefore, thinning the lens by making the shape of the lens not a circle symmetric with respect to the optical axis but a so-called oval shape by cutting an unused area is a means often used in bending optical systems. It is. On the other hand, the optical range of use of the lens near the aperture stop has a shape close to a circle, so that it cannot be cut. Also, if the aperture stop diameter is simply reduced to reduce the thickness, the F number Becomes darker. Therefore, in order to reduce the thickness of the zoom lens, an optical system that reduces the aperture stop diameter without darkening the F number is required.

On the other hand, in the variable magnification optical system having a negative, positive, negative, positive four-group configuration as in Patent Document 1, the first lens group has a negative refractive power, so the diameter of the aperture stop present in the second lens group becomes large. In addition, since the F number changes greatly between the wide-angle end and the telephoto end, the aperture stop cannot be made small, which is not suitable for downsizing.

Further, in the variable magnification optical system having a positive / negative / positive / negative five-group configuration as in Patent Document 2, the optical usage area of the fourth lens group is relatively large and has a shape close to a circle, so that it can be cut. The area is also limited and is not suitable for thinning.

In the variable magnification optical system using the reflective optical element as described in

Patent Documents

1 and 2, a lens having a negative refractive power on the object side of the reflective optical element in order to reduce the effective diameter of the first lens group. However, this lens is a factor that hinders the thinning of the zoom lens. Therefore, in the variable power optical systems shown in Patent Documents 3 and 4, instead of providing a negative lens, the reflective optical element has a negative refractive power so as to be thinned.

In a variable magnification optical system having a negative-positive-positive three-group configuration or a negative-positive-positive-positive four-group configuration as in Patent Document 3, the first lens group has a negative refractive power as in the technique of Patent Document 1. In addition, since the diameter of the aperture stop existing in the second lens group becomes large and the F number changes greatly between the wide-angle end and the telephoto end, the aperture stop cannot be made small. The effect of having a negative refractive power is limited.

In a variable power optical system having a positive / negative / positive / positive five-group configuration as in Patent Document 4, as in the technique of Patent Document 2, the optical use area of the fourth lens group becomes large and the first lens group is effective. Since the diameter also increases, the effect that the reflective optical element has a negative refractive power is limited, and is not suitable for thinning.

As another example, the variable magnification optical system of Patent Document 5 has a positive, negative, positive and negative five-group configuration and achieves a certain degree of thinning. However, since the entire length of the entire optical system is long, the unit Miniaturization is insufficient from the viewpoint of volume. Further, in Example 3, in addition to the second lens and the fourth lens, the fifth lens group moves during zooming, so that the distance between the fifth lens group and the solid-state imaging device is reduced, and the final lens is free of dust and scratches. May be susceptible. In particular, in a miniaturized zoom lens, since the final lens and the solid-state image sensor are closer to each other, the tendency is prominent. Further, since the fifth lens group moves in addition to the second lens and the fourth lens, subtle optical characteristics can be corrected during zooming. However, since three actuators are required, the entire apparatus becomes large. Furthermore, since it is necessary to provide an inter-lens width for moving the three lens groups, the overall length of the entire optical system becomes long.

JP 2007-93955 A JP 2008-65347 A Japanese Patent No. 2003-107356 JP 2011-107188 A JP 2005-215165 A

The present invention has been made in view of the above-described background art, and is a zoom lens in which various aberrations are favorably corrected while achieving compactness mainly in the thickness direction, an imaging apparatus using the same, and a portable terminal Is intended to provide.

In order to achieve the above object, a zoom lens according to the present invention has, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. The zoom lens includes a third lens group, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and performs zooming. The first lens group is a reflective lens. The first and fifth lens units are fixed and the second lens unit is moved to the image side at the time of zooming from the wide-angle end to the telephoto end, and the following conditional expression is satisfied. .
0.8 <f3 / fW <1.4 (1)
However,
f3: focal length of the third lens unit fW: focal length of the entire system at the wide-angle end

The zoom lens includes, in order from the object side, a first lens group including a reflective optical element having a positive refractive power and a function of bending a light path by reflecting a light beam, and a second lens having a negative refractive power. And a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. With such a basic configuration, it is possible to provide a zoom lens that is small and has good aberration correction.

Specifically, by providing a reflective optical element in the first lens group, the heat or size in the depth direction of the imaging device can be reduced, and the first lens group has a positive refractive power. Thus, the entrance pupil diameter can be made larger than when the first lens group has negative refractive power. Thereby, the diameter of the actual aperture stop can be reduced while maintaining the F number, which is advantageous for thinning. Further, since the change in the F number between the wide-angle end and the telephoto end can be suppressed as compared with the case where the first lens group has a negative refractive power, the F-number at the wide-angle end is made relatively dark for thinning. However, an increase in the F number at the telephoto end can be suppressed. In addition, since the third lens group has a positive refractive power and the fourth lens group has a negative refractive power, the light beam converged by the third lens group is bounced up by the fourth lens group. Since the effective diameter of the fourth lens group can be reduced compared to the positive / negative / positive / positive / positive type and the positive / negative / positive / positive / negative type, it is advantageous for thinning. In addition, the fifth lens group has a relatively large effective diameter, but its optical effective range is close to a rectangle that is the shape of the solid-state imaging device, and therefore, cutting outside the effective range of the fifth lens group is performed. Thus, it is possible to reduce the thickness. In addition, since the fifth lens group does not move at the time of zooming, a sufficient distance between the fifth lens group and the image pickup device is ensured, and it is easy to suppress the entry of dust and scratches.

In the zoom lens, the conditional expression (1) defines a suitable ratio between the focal length of the third lens group and the focal length at the wide angle end. When the value of conditional expression (1) is less than the upper limit, the third lens group has an appropriate positive refractive power, so that the light beam can be more converged, and thereby the effective diameter of the fourth lens group is reduced. It is small and is advantageous for thinning. Furthermore, the overall length of the entire optical system can be shortened, which is advantageous for downsizing. On the other hand, when the value of conditional expression (1) exceeds the lower limit, the excessive refractive power of the third lens group can be suppressed, so that the occurrence of spherical aberration and coma due to the excessive refractive power is suppressed. Is possible.
Regarding the focal length of the third lens group, it is more desirable to satisfy the following conditional expression (1) ′.
0.9 <f3 / fW <1.3 (1) ′

In a specific aspect of the present invention, the zoom lens satisfies the following conditional expression.
0.2 <f1 / fT <1.0 (2)
However,
f1: focal length of the first lens unit fT: focal length of the entire system at the telephoto end

Conditional expression (2) defines the ratio between the focal length of the first lens group and the focal length of the entire system at the telephoto end. The first lens group is a lens group in which the thickest light beam is incident at the telephoto end. When the first lens group falls below the upper limit value of the conditional expression (2), the first lens group has an appropriate refractive power. It is possible to efficiently correct aberrations such as spherical aberration and coma. On the other hand, by exceeding the lower limit value of conditional expression (2), it is possible to suppress the occurrence of aberration due to an increase in the refractive power of the first lens group.

In another aspect of the present invention, the reflective optical element reflects a light beam on the inner surface and satisfies the following conditional expression.
1.80 <nprm <2.20 (3)
However,
nprm: refractive index of the reflective optical element

Conditional expression (3) defines the refractive index of the reflective optical element. By exceeding the lower limit of the conditional expression (3), the refraction angle of the light beam incident on the reflecting optical element becomes smaller and passes closer to the optical axis, so the effective diameter of the first lens group becomes smaller. This is advantageous for downsizing. On the other hand, it can comprise with the easily available glass material by being less than the upper limit of conditional expression (3).

In still another aspect of the present invention, the reflective optical element reflects a light beam on the inner surface and satisfies the following conditional expression.
1.0 ≦ d1aPRM / dPRM <1.6 (4)
However,
d1aPRM: distance on the optical axis from the most object side surface of the first lens group to the image side surface of the reflective optical element dPRM: distance on the optical axis from the object side surface of the reflective optical element to the image side surface

Conditional expression (4) indicates that the distance on the optical axis from the most object side surface of the first lens group to the image side surface of the reflective optical element and the light from the object side surface of the reflective optical element to the image side surface. The ratio to the distance on the axis is specified. In the case of a zoom lens having a reflective optical element as in the present invention, if there is a lens on the object side of the reflective optical element, only that part becomes thicker than the others. Therefore, it is preferable not to provide a lens on the object side of the reflective optical element, or to make it thin even if a lens is provided. When the lens is provided on the object side of the reflective optical element, it is possible to suppress an increase in the thickness of the lens portion by falling below the upper limit value of conditional expression (4).

In still another aspect of the present invention, the following conditional expression is satisfied.
−1.5 <f4 / (fW × fT) ^1/2 <−0.5 (5)
However,
f4: focal length of the fourth lens unit fW: focal length of the entire system at the wide angle end fT: focal length of the entire system at the telephoto end

Conditional expression (5) defines the ratio between the focal length of the fourth lens group and the focal length intermediate between the wide-angle end and the telephoto end. By falling below the upper limit of conditional expression (5), the effect of negative jumping by the fourth lens group is added, so that off-axis rays that pass through the first to third lens groups on the object side are closer to the optical axis. It is possible to reduce the size. On the other hand, the occurrence of off-axis aberration due to excessive refractive power of the fourth lens group can be suppressed by exceeding the lower limit value of conditional expression (5).

In still another aspect of the present invention, the first lens group includes an optical element having a negative refractive power closest to the object side, and satisfies the following conditional expression.
1.0 <| f1a / fW | <6.0 (6)
However,
f1a: focal length of the optical element closest to the object side in the first lens group fW: focal length of the entire system at the wide angle end

Conditional expression (6) defines the ratio between the focal length of the optical element closest to the object side in the first lens group and the focal length of the entire system at the wide angle end. By falling below the upper limit value of conditional expression (6), the lens or the reflective optical element has an appropriate negative refractive power, and a wide angle of view can be secured at the wide angle end. On the other hand, by exceeding the lower limit value of the conditional expression (6), it is possible to suppress the occurrence of aberration due to an increase in the refractive power of the lens.
When the most object side optical element of the first lens group is a lens, it is desirable to satisfy the following conditional expression (6) ′.
1.0 <| f1a / fW | <3.0 (6) ′
When the most object side optical element of the first lens group is a lens, it is more desirable to satisfy the following conditional expression (6) ′.
1.0 <| f1a / fW | <2.6 (6) "

In yet another aspect of the present invention, the fourth lens group moves to the image side upon zooming from the wide-angle end to the telephoto end. In this case, since the movement of the fourth lens group during zooming is natural and less restrictive than the fourth lens group, the change of the image becomes relatively smooth, and the movement of the actuator that moves the lens group Can be controlled in one direction. In addition, increase and fluctuation of the F number can be suppressed relatively easily.

In yet another aspect of the present invention, the reflecting optical element is a prism and has substantially no refractive power, and the reflecting surface is substantially flat. In this case, the structure and processing of the reflective optical element can be simplified.

In still another aspect of the present invention, upon zooming from the wide-angle end to the telephoto end, the fourth lens group moves to the object side after moving to the image side, and the following conditional expression is satisfied.
−0.8 <β2W <−0.4 (7)
-3.0 <β2T <-1.0 (8)
However,
β2W: Lateral magnification at the wide-angle end of the second lens group β2T: Lateral magnification at the telephoto end of the second lens group “Movement to the object side after moving to the image side” means “wide-angle in optical design At the time of zooming from the end to the telephoto end, it moves to the object side after moving to the image side. In the embodiment, it moves to the object side after moving to the image side. This includes not only the case where the image is moved, but also the case where the image is moved to the object side and then moved to the object side, so that the amount of movement is very small.

In the zoom lens, conditional expressions (7) and (8) relate to appropriate ranges of the lateral magnifications β2W and β2T of the second lens group at the wide-angle end and the telephoto end, respectively. In general, when the amount of movement of the lens group is large, a larger actuator is required, which causes a problem that prevents the zoom lens from being thinned. On the other hand, exceeding the lower limit value of conditional expression (7) and falling below the upper limit value of (8) results in the lateral magnification of the second lens group straddling -1 when zooming from the wide-angle end to the telephoto end. Therefore, if the third lens unit is fixed at the time of zooming, the locus of zooming of the fourth lens unit has a point of inflection (a point where the positive / negative of the moving direction is reversed) instead of monotonous fluctuation, and from the wide angle end to the telephoto end. At the time of zooming, the lens moves to the object side after moving to the image side (hereinafter referred to as a movement by drawing a convex locus on the image side). Therefore, since the moving range of the fourth lens group is narrowed, it is possible to select and use a smaller actuator, and thus it is possible to further reduce the thickness. On the other hand, by moving below the upper limit of conditional expression (7), it is possible to suppress the amount of movement of the fourth lens group from the wide-angle end to the inflection point. Further, exceeding the lower limit value of conditional expression (8) makes it possible to suppress the amount of movement of the fourth lens group from the inflection point to the telephoto end.

In still another aspect of the present invention, in the zoom lens in which the fourth lens group moves to the object side after moving to the image side, the reflective optical element has substantially no refractive power.

In yet another aspect of the present invention, the reflective optical element having substantially no refractive power is a prism, and the most object side surface and the reflective surface of the prism are substantially flat.

In still another aspect of the invention, the zoom lens that moves to the object side after the fourth lens group moves to the image side satisfies the following conditional expression.
1.5 <m2 / m4 <12.0 (9)
However,
m2: Maximum moving amount of the second lens unit at zooming from the wide angle end to the telephoto end m4: Maximum moving amount of the fourth lens unit at zooming from the wide angle end to the telephoto end

Conditional expression (9) defines a ratio between the maximum movement amount of the second lens group and the maximum movement amount of the fourth lens group at the zooming from the wide-angle end to the telephoto end. The maximum amount of movement here is the distance from the wide-angle end to the inflection point when the lens group draws a trajectory with the inflection point when zooming from the wide-angle end to the telephoto end when the object distance is infinity. The larger of the travel distance from the inflection point to the telephoto end. By exceeding the lower limit value of conditional expression (9), the amount of movement of the fourth lens group becomes small, and it becomes possible to select and use various smaller actuators, thereby enabling further reduction in thickness. . On the other hand, by falling below the upper limit value of conditional expression (9), it is possible to suppress an increase in the total length due to an increase in the amount of movement of the second lens group.

In yet another aspect of the present invention, the reflective optical element is disposed closest to the object side and has negative refractive power. As described above, when the negative lens is arranged on the object side of the reflective optical element while suppressing an increase in the effective diameter of the first lens group by arranging the reflective optical element having the negative refractive power on the most object side. In comparison, the size of the imaging device in the thickness direction can be further reduced.

In yet another aspect of the present invention, the most object side surface of the reflective optical element is a concave surface. In this case, the portion having the negative refractive power of the reflective optical element is disposed on the object side, and the effect of reducing the effective diameter of the first lens group can be enhanced.

In yet another aspect of the present invention, in the zoom lens in which the reflecting optical element has negative refractive power, the fourth lens group moves to the image side upon zooming from the wide angle end to the telephoto end.

In still another aspect of the present invention, a zoom lens in which the reflective optical element has negative refractive power satisfies the following conditions.
0.4 <d11 / fW <0.9 (10)
However,
d11: Distance from the vertex of the most object-side surface of the first lens group to the intersection of the reflecting surface of the reflecting optical element and the optical axis fW: Focal length of the entire zoom lens system at the wide angle end

Conditional expression (10) defines the distance from the vertex of the most object-side surface of the first lens unit to the intersection of the reflecting surface of the reflecting optical element and the optical axis, and the ratio of the focal length of the entire system at the wide-angle end. is doing. When the value of conditional expression (10) is less than the upper limit, it is possible to reduce the thickness in the vicinity of the reflective optical element that often determines the thickness of the imaging device, thereby reducing the thickness of the imaging device. It becomes possible. On the other hand, when the value of conditional expression (10) exceeds the lower limit, excessively thinning of the reflective optical element can be avoided. If the angle of the reflecting surface with respect to the optical axis cannot be maintained at 45 degrees due to the promotion of excessive thinning, the cutting range of the object side surface of the reflecting optical element is expanded, resulting in a significant decrease in the amount of peripheral light. Equation (10) is effective.
Regarding the distance from the object side surface of the reflecting optical element to the intersection of the reflecting surface and the optical axis, it is desirable to satisfy the following conditional expression (10) ′.
0.5 <d11 / fW <0.8 (10) ′

In still another aspect of the present invention, a zoom lens in which the reflective optical element has negative refractive power satisfies the following conditions.
−3.0 <r1 / d1 <−1.5 (11)
However,
r1: Paraxial radius of curvature of the object-side optical surface of the reflective optical element d1: Distance on the optical axis from the object-side optical surface to the image-side optical surface of the reflective optical element

Conditional expression (11) is a preferred ratio between the paraxial radius of curvature of the object-side optical surface of the reflective optical element and the distance on the optical axis from the object-side optical surface to the image-side optical surface of the reflective optical element. Is stipulated. When the value of conditional expression (11) exceeds the lower limit, the object-side optical surface has an appropriate negative refractive power, and the effective diameter of the first lens group can be suppressed. Become. On the other hand, when the value of conditional expression (11) is less than the upper limit, the curvature of the object-side optical surface can be prevented from becoming excessively large with respect to the thickness of the reflective optical element, and after the light beam is reflected by the reflective surface. It is possible to effectively suppress the generation of unnecessary ghosts and the like that are generated by entering the object surface again.

In still another aspect of the present invention, a zoom lens in which the reflective optical element has negative refractive power satisfies the following conditions.
−3.0 <(r1 + r2) / (r1−r2) <− 0.5 (12)
However,
r1: Paraxial radius of curvature of the optical surface on the object side of the reflecting optical element r2: Paraxial radius of curvature of the optical surface on the image side of the reflecting optical element

Conditional expression (12) defines the shaping factor of the reflective optical element. In the basic configuration of the present invention, the first lens group as a whole has a positive refractive power, while the reflective optical element therein has a negative refractive power. This means that the first lens group has a rear group having positive refractive power on the image side of the reflective optical element. Therefore, it can be said that the first lens group has a retrofocus configuration of two negative positive groups. In this case, since the principal point of the reflective optical element moves to the object side when the value of the conditional expression (12) is below the upper limit, the effect of retrofocus is further increased and the refractive power of each group is not increased so much. In addition, since it is possible to increase the refractive power of the first lens group, it is possible to suppress the occurrence of aberrations. On the other hand, when the value of conditional expression (12) exceeds the lower limit, the curvature of the object-side optical surface can be prevented from becoming excessively large, and after the light beam is reflected by the reflecting surface, it enters the object surface again. It is possible to suppress the occurrence of unnecessary ghosts and the like.

In yet another aspect of the present invention, the zoom lens performs focusing by moving the fourth lens group. As described above, by focusing with the fourth lens group, it is possible to obtain a clear image up to a short distance object without causing an increase in the total optical length or an increase in the front lens diameter due to the extension.

In still another aspect of the present invention, the third lens group does not move in the optical axis direction during zooming or focusing.
In the positive / negative / positive / negative / positive five-group configuration as in the present invention, since the third lens group tends to require a large refractive power, it is desirable to use a plurality of lenses in order to suppress the occurrence of aberrations. In such a case, when the third lens group is moved, a larger actuator is required, which hinders the reduction in the thickness of the zoom lens. Therefore, fixing the third lens group is advantageous for downsizing.

In yet another aspect of the present invention, the fifth lens group does not move in the optical axis direction during focusing. In this case, since the fifth lens group does not move, the distance between the final lens and the solid-state image sensor is fixed. Therefore, the solid-state image sensor can be sealed by the fifth lens group and its lens frame, and dust can be removed. The occurrence of contamination and scratches can be suppressed, and the influence of dust and scratches can be suppressed.

In still another aspect of the invention, the third lens group includes at least two lenses having positive refractive power.
In a variable power optical system having a conventional positive / negative / positive / positive / positive 5 group configuration or positive / negative / positive / positive / negative 5 group configuration, both the third and fourth lens groups distribute positive refractive power. The force is not so large, and a large aberration often does not occur even with a single lens. On the other hand, in the positive / negative / positive / negative / positive five-group configuration as in the present invention, since the fourth lens group has a negative refractive power, it is necessary that only the third lens group has a positive refractive power. Is required. Therefore, by providing at least two lenses having positive refractive power in the third lens group, it becomes possible to distribute the refractive power by a plurality of lenses even when it is intended to ensure a large refractive power of the third lens group. Thus, it becomes possible to suppress the occurrence of aberrations. It is more desirable that the third lens group has at least three lenses having positive refractive power.

In yet another aspect of the present invention, an aperture stop is disposed in the third lens group. Thereby, the configuration of the refractive power in the entire lens system becomes a symmetric system, and various aberrations that can be corrected by symmetrical shapes such as distortion, coma, and lateral chromatic aberration can be effectively corrected. Further, since the aperture stop is fixed at the time of zooming or focusing, even when a mechanical shutter, an ND filter or the like is mounted on the aperture stop, an excessive load is not applied to the actuator. The aperture stop may be disposed anywhere on the most object side, inside the lens group, and on the most image side of the third lens group.

In still another aspect of the present invention, the fifth lens group is a single lens made of plastic, and at least one surface of the fifth lens group is aspheric. The fifth lens group is a lens group arranged closest to the image side, and the light beam passing through the lens is thinner than the other lens groups. Therefore, the influence of the change in refractive power on the whole is small compared to other lens groups, and even if a single lens made of plastic is used, the influence on the optical performance due to the temperature change can be suppressed. Moreover, since the plastic lens by injection molding can easily manufacture an aspherical lens, each aspherical lens can effectively correct each aberration such as field curvature and distortion.

In still another aspect of the present invention, a lens having substantially no power is further included.

An image pickup apparatus according to the present invention includes the zoom lens described above and an image pickup element that photoelectrically converts an image formed on the image pickup surface by the zoom lens. By using the zoom lens of the present invention, it is possible to obtain an image pickup apparatus that achieves compactness mainly in the thickness direction and further suppresses various aberrations.

A mobile terminal according to the present invention includes the above-described imaging device and a display unit that displays an image. By using the imaging device of the present invention, it is possible to obtain a mobile terminal that is mainly compact in the thickness direction.

As used herein, “mobile terminal” is a generic term for communication devices (mobile communication devices / terminals) and information devices (portable information devices / terminals) that can be carried and used, including mobile phones, PDAs, smartphones, and the like. It is.

It is a figure explaining an imaging device or a module provided with the zoom lens of a 1st embodiment concerning the present invention. It is a figure explaining an imaging device provided with the zoom lens of a modification. It is a block diagram explaining a portable communication terminal provided with the imaging device of FIG. 1 or FIG. 4A and 4B are perspective views of the front side and the back side of the mobile communication terminal. It is a perspective view which shows the zoom lens etc. of 2nd Embodiment. It is a block diagram of the imaging device which has the zoom lens of 2nd Embodiment. 7A is a cross-sectional view at the wide-angle end of Example 1, FIG. 7B is a cross-sectional view at the middle, and FIG. 7C is a cross-sectional view at the telephoto end. FIG. 8A is an aberration diagram at the wide-angle end in Example 1, FIG. 8B is an aberration diagram at the middle, and FIG. 8C is an aberration diagram at the telephoto end. 9A is a cross-sectional view at the wide-angle end of Example 2, FIG. 9B is a cross-sectional view in the middle, and FIG. 9C shows that the lateral magnification of the second lens group is −1 and the fourth lens group has an inflection point. FIG. 9D is a cross-sectional view at the telephoto end. FIG. 10A is an aberration diagram at the wide-angle end of Example 2, and FIG. 10B is an aberration diagram at the middle. FIG. 11A is an aberration diagram when the fourth lens group is located at the inflection point, and FIG. 11B is an aberration diagram at the telephoto end. 12A is a cross-sectional view at the wide-angle end of Example 3, FIG. 12B is a cross-sectional view in the middle, and FIG. 12C shows that the lateral magnification of the second lens group is −1 and the fourth lens group has an inflection point. FIG. 12D is a cross-sectional view at the telephoto end. FIG. 13A is an aberration diagram at the wide-angle end of Example 3, and FIG. 13B is an aberration diagram at the middle. FIG. 14A is an aberration diagram when the fourth lens group is located at the inflection point, and FIG. 14B is an aberration diagram at the telephoto end. 15A is a cross-sectional view at the wide-angle end of Example 4, and FIG. 15B is a cross-sectional view when the lateral magnification of the second lens group is −1 and the fourth lens group is at the position of the inflection point. 15C is a cross-sectional view in the middle, and FIG. 15D is a cross-sectional view at the telephoto end. FIG. 16A is an aberration diagram at the wide-angle end of Example 4, and FIG. 16B is an aberration diagram when the fourth lens group is located at an inflection point. FIG. 17A is an aberration diagram in the middle, and FIG. 17B is an aberration diagram at the telephoto end. 18A is a cross-sectional view at the wide-angle end of Example 5, FIG. 18B is a cross-sectional view in the middle, and FIG. 18C shows that the lateral magnification of the second lens group is −1 and the fourth lens group has an inflection point. FIG. 18D is a cross-sectional view at the telephoto end. FIG. 19A is an aberration diagram at the wide-angle end of Example 5, and FIG. 19B is an aberration diagram at the middle. FIG. 20A is an aberration diagram when the fourth lens group is located at the inflection point, and FIG. 20B is an aberration diagram at the telephoto end. FIG. 21A is a cross-sectional view at the wide-angle end of Example 6, FIG. 21B is a cross-sectional view in the middle, and FIG. 21C shows that the lateral magnification of the second lens group is −1 and the fourth lens group has an inflection point. FIG. 21D is a cross-sectional view at the telephoto end. FIG. 22A is an aberration diagram at the wide-angle end of Example 6, and FIG. 22B is an aberration diagram at the middle. FIG. 23A is an aberration diagram when the fourth lens group is located at the inflection point, and FIG. 23B is an aberration diagram at the telephoto end. FIG. 24A is a cross-sectional view at the wide-angle end of Example 7, and FIG. 24B is a cross-sectional view when the lateral magnification of the second lens group is −1 and the fourth lens group is at the position of the inflection point. 24C is a cross-sectional view in the middle, and FIG. 24D is a cross-sectional view at the telephoto end. FIG. 25A is an aberration diagram at the wide-angle end of Example 7, and FIG. 25B is an aberration diagram when the fourth lens group is located at a position of the inflection point. FIG. 26A is an aberration diagram in the middle, and FIG. 26B is an aberration diagram at the telephoto end. 27A is a cross-sectional view at the wide-angle end of Example 8, FIG. 27B is a cross-sectional view in the middle, and FIG. 27C shows that the lateral magnification of the second lens group is −1 and the fourth lens group has an inflection point. FIG. 27D is a cross-sectional view at the telephoto end. FIG. 28A is an aberration diagram at the wide-angle end in Example 8, and FIG. 28B is an aberration diagram at the middle. FIG. 29 is an aberration diagram when the fourth lens group is located at the inflection point, and FIG. 29B is an aberration diagram at the telephoto end. 10 is a cross-sectional view of a zoom lens according to Example 9. FIG. 31A to 31C are cross-sectional views of the zoom lens of Example 9. FIGS. 32A to 32C are aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens of Example 9. FIGS. 33A to 33C are cross-sectional views of the zoom lens of Example 10. FIG. 34A to 34C are aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens of Example 10. FIGS. FIGS. 35A to 35C are cross-sectional views of the zoom lens of Example 11. FIGS. 36A to 36C are aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens of Example 11. FIGS. 37A to 37C are cross-sectional views of the zoom lens of Example 12. FIGS. 38A to 38C are aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens according to the twelfth embodiment. 39A to 39C are cross-sectional views of the zoom lens according to the thirteenth embodiment. 40A to 40C are aberration diagrams (spherical aberration, astigmatism, distortion) of the zoom lens of Example 13. FIGS.

[First Embodiment]
FIG. 1 is a cross-sectional view illustrating a camera module as an imaging apparatus including the zoom lens according to the first embodiment of the present invention.

The camera module (imaging device) 50 includes a zoom lens 10 that forms a subject image, an image sensor 51 that photoelectrically converts the subject image formed by the zoom lens 10, and holds the image sensor 51 from behind and wiring and the like. A wiring board 52 having a zoom lens 10 and the like, and a lens barrel portion 54 having an opening OP for allowing light rays from the object side to enter the zoom lens 10 are provided. The zoom lens 10 has a function of forming a subject image on the imaging surface (or projection surface) I of the image sensor 51. This camera module 50 is used by being incorporated in a portable terminal described later.

The zoom lens 10 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3 (including an aperture stop S), a fourth lens group Gr4, and a fifth lens group Gr5. With. Each of the lens groups Gr1 to Gr5 can be composed of a single lens or a plurality of lenses. The first lens group Gr1 incorporates a triangular prismatic reflective optical element PRM that bends the optical path by reflection, and reflects light toward the −Z direction by an inclined inner surface (or reflecting surface) 12a, thereby 90 °. Bend it in the + Y direction. That is, the optical axis AX extends orthogonally across the inner surface 12a, and has an axis AX1 parallel to the Y axis and an axis AX2 parallel to the Z axis. In the first lens group Gr1, on the object side of the reflective optical element PRM, a first lens L11 having a negative refractive power is disposed so as to cover the reflective optical element PRM. The zoom lens 10 illustrated in FIG. 1 has the same configuration as the zoom lens 11 of Example 1 described later.

The image sensor 51 is a sensor chip made of a solid-state image sensor. The photoelectric conversion unit 51a of the image sensor 51 is composed of a CCD (charge coupled device) or a CMOS (complementary metal oxide semiconductor), photoelectrically converts incident light for each pixel of RGB, and outputs an analog signal thereof. The surface of the photoelectric conversion unit 51a as the light receiving unit is an imaging surface (projected surface) I.

The wiring substrate 52 has a role of aligning and fixing the image pickup device 51 to other members (for example, the lens barrel portion 54) via a support. The wiring board 52 receives supply of voltages and signals for driving the image sensor 51 and the first and

second drive mechanisms

55a and 55b from an external circuit, and outputs a detection signal to the external circuit. Is possible.

On the zoom lens 10 side of the image pickup device 51, a parallel plate F made of, for example, an IR cut filter, an optical low-pass filter, or the like is disposed and fixed by a holder member (not shown) so as to cover the image pickup device 51 and the like. .

The lens barrel portion 54 houses and holds the zoom lens 10. The lens barrel portion 54 moves the second and fourth lens groups Gr2 and Gr4 among the lens groups Gr1 to Gr5 constituting the zoom lens 10 along the optical axis AX, thereby changing the magnification and focusing of the zoom lens 10. In order to enable this operation, the first and

second drive mechanisms

55a and 55b are provided. Both drive

mechanisms

55a and 55b can operate independently. One first drive mechanism 55a reciprocates the second lens group Gr2 along the optical axis AX, and the other second drive mechanism 55b The four lens group Gr4 is reciprocated along the optical axis AX. The first drive mechanism 55a includes, for example, a stepping motor, a tangent screw type power transmission member, and a slide guide. The second drive mechanism 55b includes a voice coil motor and a guide, for example. The drive mechanism is not limited to the above, and the first drive mechanism 55a may be configured by an actuator using a piezoelectric element instead of a stepping motor (see, for example, US 5,589,723), a voice coil motor, or the like. Alternatively, the second drive mechanism 55b may be composed of an actuator using a piezoelectric element, a stepping motor, or the like instead of the voice coil motor.

Hereinafter, the zoom lens 10 will be described in detail. The zoom lens 10 in FIG. 1 forms a subject image on the imaging surface I of the image sensor 51, and in order from the object side, the first lens group Gr1 having a positive refractive power and a negative refractive power. The second lens group Gr2 includes a third lens group Gr3 having a positive refractive power, a fourth lens group Gr4 having a negative refractive power, and a fifth lens group Gr5 having a positive refractive power. Here, the first lens group Gr1 includes, for example, a substantially flat and negative first lens L11, a reflective optical element PRM that is a prism mirror, and a biconvex and positive second lens L12. The second lens group Gr2 includes, for example, a biconcave negative third lens L21, a biconcave negative fourth lens L22, and a biconvex fifth lens L23 which is cemented to the lens L22. The third lens group Gr3 includes, for example, an aperture stop S, a biconvex positive sixth lens L31, a negative seventh lens L32 convex to the object side, and a biconvex positive eighth lens that is cemented to the lens L32. L33. The fourth lens group Gr4 includes, for example, a negative meniscus ninth lens L41 that is convex on the object side. The fifth lens group Gr5 includes, for example, a positive meniscus tenth lens L51 that is convex on the object side. The aperture stop S is not limited to the most object side of the third lens group Gr3, but can be disposed inside the lens group (between the lenses L31 to L33) or the most image side (the image side of the lens L33). The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

The zoom lens 10 in FIG. 1 changes the positions of the second lens group Gr2 and the fourth lens group Gr4 among the first to fifth lens groups Gr1 to Gr5 when zooming from the wide-angle end to the telephoto end. Specifically, during zooming from the wide-angle end to the telephoto end, the first, third, and fifth lens groups Gr1, Gr3, and Gr5 are fixed with respect to the imaging surface I and the like and do not move, and the second lens The group Gr2 moves to the image side, and the fourth lens group Gr4 also moves to the image side.

The camera module 50 shown in FIG. 2 is a modified example of the camera module 50 of FIG. 1 and has the same structure. Therefore, the same parts as those of the camera module 50 of FIG. Description is omitted. The zoom lens 10 illustrated in FIG. 2 has the same configuration as the zoom lens 12 of Example 2 described later.

The zoom lens 10 shown in FIG. 2 forms a subject image on the imaging surface I of the image sensor 51, and in order from the object side, the first lens group Gr1 having a positive refractive power and a negative refractive power. A second lens group Gr2 having positive refractive power, a third lens group Gr3 having positive refractive power, a fourth lens group Gr4 having negative refractive power, and a fifth lens group Gr5 having positive refractive power. Here, the first lens group Gr1 includes, for example, a plano-concave negative first lens L11, a reflective optical element PRM that is a prism mirror, and a biconvex positive second lens L12. The second lens group Gr2 includes, for example, a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes, for example, an aperture stop S, a biconvex positive fifth lens L31, a negative sixth lens L32 convex to the object side, and a biconvex positive seventh lens which is cemented to the lens L32. L33. The fourth lens group Gr4 includes, for example, a biconcave negative eighth lens L41. The fifth lens group Gr5 includes, for example, a positive meniscus ninth lens L51 that is convex on the object side. The aperture stop S is not limited to the most object side of the third lens group Gr3, but can be disposed inside the lens group (between the lenses L31 to L33) or the most image side (image side of the lens L33). The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

The zoom lens 10 in FIG. 2 has a positive, negative, positive, and positive five-group configuration, and the first lens L11 having negative refractive power in the first lens group Gr1 is disposed on the object side of the reflective optical element PRM. Although similar to the zoom lens 10 of FIG. 1, the movement of the lens during zooming is different from that of the zoom lens 10 of FIG.

The zoom lens 10 in FIG. 2 changes the positions of the second lens group Gr2 and the fourth lens group Gr4 among the first to fifth lens groups Gr1 to Gr5 when zooming from the wide-angle end to the telephoto end. More specifically, in the case of the zoom lens 10 shown in FIG. 2, the first, third, and fifth lens groups Gr1, Gr3, and Gr5 are fixed with the imaging surface I as a reference when zooming from the wide-angle end to the telephoto end. Thus, the second lens group Gr2 moves to the image side and the fourth lens group Gr4 once moves to the image side, and then moves to the object side in the middle or becomes substantially stationary.

Next, an example of a mobile communication terminal 300 that is a mobile terminal equipped with the camera module 50 illustrated in FIGS. 1 and 2 will be described with reference to FIGS. 3, 4A, and 4B.

The mobile communication terminal 300 is a smartphone-type mobile communication terminal, and includes an imaging function unit 200 having a camera module 50 that is an imaging device, and a control unit that comprehensively controls each unit and executes a program corresponding to each process ( CPU) 310, display operation unit 320 that is a touch panel that displays data related to communication, captured images and videos, and receives user operations, an operation unit 330 including a power switch, and the like, via antenna 341 A wireless communication unit 340 for realizing various types of information communication with an external server and the like, and a storage unit (ROM that stores necessary data such as a system program, various processing programs, and a terminal ID of the mobile communication terminal 300 360, various processing programs and data executed by the control unit 310, processing data, Includes a temporary storage unit (RAM) 370 or the like used as a work area for temporarily storing the imaging data and the like by the imaging function unit 200.

The imaging function unit 200 includes a control device 74, an optical system driving circuit unit 105a, an imaging element driving device 77, an image storage device 78, and the like in addition to the camera module 50 described above.

The control device 74 controls each unit of the imaging function unit 200. The control device 74 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like, and various types of programs are read out from the ROM and expanded in the RAM in cooperation with the CPU. Execute the process. The control unit 310 is communicably connected to the control device 74 of the imaging function unit 200, and can exchange control signals and image data.

The optical system drive circuit unit 105a operates the first and

second drive mechanisms

55a and 55b of the zoom lens 10 to change the state of the zoom lens 10 when performing zooming, focusing, exposure, and the like under the control of the control device 74. To control. The optical system drive circuit unit 105a operates the first drive mechanism 55a to appropriately move the second lens group Gr2 along the optical axis AX, and operates the second drive mechanism 55b to light the fourth lens group Gr4. By appropriately moving along the axis AX, the zoom lens 10 is caused to perform a zoom operation. That is, during the zoom operation, the first, third, and fifth lens groups Gr1, Gr3, and Gr5 are fixed. During zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves to the image side (+ Y side in FIG. 1). The fourth lens group Gr4 moves to the image side (+ Y side in FIG. 1) in the case of the zoom lens 10 corresponding to FIG. 1, and the image side (in FIG. 1) in the case of the zoom lens 10 corresponding to FIG. After moving to the + Y side), it moves to the object side (-Y side in FIG. 1). As a result, in the zoom lens 10 corresponding to FIG. 2, the fourth lens group Gr4 moves along a locus convex toward the image side. In the zoom lens 10 corresponding to FIG. 2, the movement of the fourth lens group Gr4 at the time of zooming from the wide-angle end to the telephoto end is not limited to the case where the fourth lens group Gr4 moves relatively backward after moving to the image side. In some cases, the image becomes substantially stationary at the position closest to the image side (+ Y side in FIG. 1) after moving to. On the other hand, the zoom lens 10 can be focused. In other words, the optical system drive circuit unit 105a of the zoom lens 10 shown in FIGS. 1 and 2 operates the second drive mechanism 55b to appropriately move the fourth lens group Gr4 along the optical axis AX, whereby the zoom lens 10 To perform the focusing operation. During the focusing operation, the first to third and fifth lens groups Gr1 to Gr3 and Gr5 are fixed. It is also possible to move only the second lens group Gr2 during zooming operation and move only the fourth lens group Gr4 during focusing operation.

The image sensor driving device 77 controls the operation of the image sensor 51 when performing exposure or the like under the control of the control device 74. Specifically, the image sensor driving device 77 scans and controls the image sensor 51 based on the timing signal. Further, the image sensor driving device 77 converts the detection signal output from the image sensor 51 or an analog signal as a photoelectric conversion signal into digital image data. Further, the image sensor driving device 77 can perform various image processing such as distortion correction, color correction, and compression on the image signal sent from the image sensor 51.

The image storage device 78 receives the digitized image signal from the image sensor driving device 77 and stores it as readable and writable image data.

Here, the photographing operation of the mobile communication terminal 300 including the imaging function unit 200 will be described. When the camera mode in which the mobile communication terminal 300 is operated as a camera is set, subject monitoring (through image display) and image shooting execution are performed. In monitoring, an image of the subject obtained through the zoom lens 10 is formed on the imaging surface I (see FIG. 1 and the like) of the imaging element 51. The image sensor 51 is scanned and driven by the image sensor driving device 77, and outputs an analog signal for one screen as a photoelectric conversion output corresponding to a light image formed at regular intervals.

This analog signal is converted into digital data after gain adjustment is appropriately performed for each primary color component of RGB in a circuit attached to the image sensor 51. The digital data is subjected to color process processing including pixel interpolation processing and Y correction processing to generate digital luminance signals Y and color difference signals Cb, Cr (image data) and store them in the image storage device 78. . The stored digital data is periodically read out from the image storage device 78 to generate a video signal thereof, and is output to the display operation unit 320 via the control device 74 and the control unit 310.

This display operation unit 320 functions as an electronic viewfinder in monitoring, and displays captured images in real time. In this state, zooming, focusing, exposure, and the like of the zoom lens 10 are set by driving the optical system driving circuit unit 105a based on an operation input performed by the user via the display operation unit 320 as needed.

In such a monitoring state, when the user appropriately operates the display operation unit 320, still image data is captured. One frame of image data stored in the image storage device 78 is read in accordance with the operation content of the display operation unit 320 and compressed by the image sensor driving device 77. The compressed image data is recorded in the RAM 370, for example, via the control device 74 and the control unit 310.

Note that the above-described imaging function unit 200 is an example of a configuration suitable for the present invention, and the present invention is not limited to this.

In other words, the camera module 50 that is an imaging device equipped with the zoom lens 10 is not limited to the one built in the smartphone type mobile communication terminal 300, but is built into a mobile phone, a PHS (Personal Handyphone System), or the like. Alternatively, it may be incorporated in a PDA (Personal Digital Assistant), tablet personal computer, mobile personal computer, digital still camera, video camera, or the like.

Hereinafter, numerical conditions satisfied by the zoom lens 10 according to the first embodiment shown in FIGS. 1 and 2 will be described. The zoom lens 10 of FIGS. 1 and 2 has the conditional expression (1) already described.
0.8 <f3 / fW <1.4 (1)
Satisfied. Here, f3 is the focal length of the third lens group Gr3, and fW is the focal length of the entire zoom lens 10 system at the wide angle end.
The value f3 / fW is more preferably in the range of the following equation.
0.9 <f3 / fW <1.3 (1) ′

In the zoom lens 10 of the first embodiment, in addition to the conditional expression (1), the conditional expression (2) already described.
0.2 <f1 / fT <1.0 (2)
Satisfied. Here, f1 is the focal length of the first lens group Gr1, and fT is the focal length of the entire zoom lens 10 system at the telephoto end.

In the zoom lens 10 of the first embodiment, in addition to the conditional expression (1) and the like, the conditional expression (3) already described.
1.80 <nprm <2.20 (3)
Satisfied. Here, f1 is the focal length of the first lens group Gr1, and fT is the focal length of the entire zoom lens 10 system at the telephoto end.

In the zoom lens 10 according to the first embodiment, in addition to the conditional expression (1), the conditional expression (4) already described.
1.0 ≦ d1aPRM / dPRM <1.6 (4)
Satisfied. Here, d1aPRM is a distance on the optical axis from the object-side surface of the lens L11 closest to the object side of the first lens group Gr1 to the image-side surface 11a of the reflective optical element PRM.

In the zoom lens 10 according to the first embodiment, in addition to the conditional expression (1), the conditional expression (5) already described.
−1.5 <f4 / (fW × fT) ^1/2 <−0.5 (5)
Satisfied. Here, f4 is the focal length of the fourth lens group Gr4, and fT is the focal length of the entire zoom lens 10 system at the telephoto end.

In the zoom lens 10 of the first embodiment, in addition to the conditional expression (1) and the like, the conditional expression (6) already described.
1.0 <| f1a / fW | <6.0 (6)
Satisfied. Here, f1a is the focal length of the lens L11 that is the optical element closest to the object side of the first lens group Gr1.
The value f3 / fW is more preferably in the range of the following equation.
1.0 <| f1a / fW | <3.0 (6) ′
1.0 <| f1a / fW | <2.6 (6) "

In particular, in the zoom lens 10 of the type shown in FIG. 1, in addition to the conditional expression (1), the conditional expressions (7) and (8) already described.
−0.8 <β2W <−0.4 (7)
-3.0 <β2T <-1.0 (8)
Satisfied. However, β2W is the lateral magnification at the wide-angle end of the second lens group Gr2, and β2T is the lateral magnification at the telephoto end of the second lens group Gr2.

In particular, in the zoom lens 10 of the type shown in FIG. 1, in addition to the conditional expression (1), the conditional expression (9) already described.
1.5 <m2 / m4 <12.0 (9)
Satisfied. Here, m2 is the maximum movement amount of the second lens group Gr2 at zooming from the wide-angle end to the telephoto end, and m4 is the maximum movement of the fourth lens group Gr4 at zooming from the wide-angle end to the telephoto end. Amount.

[Second Embodiment]
Hereinafter, a zoom lens according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a perspective view showing only the main part of the image pickup apparatus including the zoom lens according to the present embodiment, but is schematically drawn unlike an actual zoom lens. FIG. 6 is a block diagram of an imaging apparatus incorporating the zoom lens according to the present embodiment. The imaging device shown in FIGS. 5 and 6 can be built in a portable terminal or other devices, as in the case of the first embodiment shown in FIG.

In FIG. 6, the zoom lens ZL of the second embodiment has, in order from the object side, a first lens group Gr1 having a positive refractive power, a second lens group Gr2 having a negative refractive power, and a positive refractive power. The third lens group Gr3 includes a fourth lens group Gr4 having negative refractive power, and a fifth lens group Gr5 having positive refractive power, and zooming is performed by changing the interval between the lens groups. It has become. Specifically, the first lens group Gr1 is fixed and the second lens group Gr2 and the fourth lens group Gr4 move to the image side by zooming from the wide-angle end to the telephoto end. Further, the first lens group Gr1 includes a reflective optical element (prism) PRM having a negative refractive power having an action of bending a light path by reflecting a light beam to the most object side. The zoom lens ZL illustrated in FIG. 6 has the same configuration as the zoom lens of Example 9 described later.

In FIG. 5, the imaging surface I of the rectangular solid-state imaging device has a long side in the vertical direction and a short side in the horizontal direction. The optical axis passing through the center of the imaging surface I is OX, and the optical axis bent to the object side by the prism PRM is OY (parallel to the short side of the imaging surface I). The prism PRM has an object side optical surface PRM1, an image side optical surface PRM2, and a reflection surface PRM3, and the optical axes OX and OY are orthogonal to each other on the reflection surface PRM3. The object-side optical surface PRM1 has a substantially circular concave surface CP centered on the optical axis OY and a surrounding plane FP. The light beam that has passed through the concave surface CP is received by the rectangular imaging surface I of the solid-state imaging device. Therefore, the contour of the concave surface CP protrudes on the long side of the object side optical surface PRM1, and light rays unnecessary for imaging are not incident. The image side optical surface PRM2 may be a flat surface, or a convex surface or a concave surface.

In the zoom lens ZL, at least the most image side lens FLS has an oval shape or an oval shape, and corresponding to the imaging surface I of the solid-state imaging device, both sides on the long side are cut to provide a linear portion (cutting portion) C. It has been. Thereby, the thickness of the zoom lens ZL in the optical axis OY direction can be reduced as much as possible.

6, a solid-state image sensor 102 is an image sensor such as a CCD or a CMOS, and includes an RGB color filter. The solid-state image sensor 102 photoelectrically converts incident light for each of R, G, and B, and outputs an analog signal thereof. The A / D conversion unit 103 converts an analog signal into digital image data.

The control unit 104 controls each unit of the imaging apparatus 100. The control unit 104 includes a CPU, a RAM, and a ROM, and executes various processes in cooperation with various programs read from the ROM and expanded in the RAM.

The optical system driving unit 105 drives and controls the zoom lens ZL during zooming, focusing, exposure, and the like under the control of the control unit 104. The timing generator 106 outputs a timing signal for analog signal output. The image sensor drive unit 107 performs scanning drive control of the solid-state image sensor 102.

The image memory 108 stores image data so as to be readable and writable. The image processing unit 109 performs various image processes on the image data. The image compression unit 110 compresses captured image data by a compression method such as JPEG (Joint Photographic Experts Group). The image recording unit 111 records image data on a recording medium such as a memory card set in a slot (not shown).

The monitor LCD 112 is a color liquid crystal panel or the like, and displays image data after shooting, a through image before shooting, various operation screens, and the like. The operation unit 113 outputs information input by the user to the control unit 104 via a button group (not shown).

Here, the operation of the imaging apparatus 100 will be described. In subject photographing, subject monitoring (through image display) and image photographing execution are performed. In monitoring, an image of the subject obtained through the zoom lens ZL is formed on the light receiving surface (imaging surface I) of the solid-state image sensor 102. Further, the solid-state imaging device 102 is scanned and driven by the timing generation unit 106 and the imaging device driving unit 107, and outputs an analog signal for one screen as a photoelectric conversion output corresponding to an optical image formed at regular intervals.

The analog signal is appropriately gain-adjusted for each primary color component of RGB, and then converted into digital data by the A / D conversion unit 103. The digital data is subjected to color process processing including pixel interpolation processing and γ correction processing by the image processing unit 109 to generate a digital luminance signal Y and color difference signals Cb, Cr (image data). And stored in the image memory 108. Also, the image data stored in the image memory 108 is periodically read out, and the video signal is generated and output to the monitor LCD 112. Note that the control unit 104 as white balance adjustment means adjusts the white balance so that the signal intensity of the blue wavelength component in the image signal is smaller than the signal intensity of other colors.

The monitor LCD 112 functions as an electronic viewfinder in monitoring and displays captured images in real time. In this state, zooming / focusing, focusing, exposure, etc. of the zoom lens ZL are set by driving the optical system driving unit 105 based on an input through the operation unit 113 made in response to the photographer's release button operation. Is done.

In such a monitoring state, still image data is photographed when the user operates a release button (not shown) at a timing when it is desired to shoot a still image. In response to the operation of the release button, one frame of image data stored in the image memory 108 is read out and compressed by the image compression unit 110. The compressed image data is recorded in the removable memory by the image recording unit 111.

Hereinafter, numerical conditions satisfied by the zoom lens ZL of the second embodiment shown in FIG. 5 or 6 will be described. In the zoom lens ZL of the second embodiment, the conditional expressions (1) to (6) already described are the same as in the case of the first embodiment.
0.8 <f3 / fW <1.4 (1)
0.2 <f1 / fT <1.0 (2)
1.80 <nprm <2.20 (3)
1.0 ≦ d1aPRM / dPRM <1.6 (4)
−1.5 <f4 / (fW × fT) ^1/2 <−0.5 (5)
1.0 <| f1a / fW | <6.0 (6)
Meet. In conditional expression (6), f1a is the focal length of the reflective optical element (prism) PRM, which is the optical element closest to the object side of the first lens group Gr1.

In the zoom lens ZL of the second embodiment, in addition to the conditional expression (1), the conditional expression (10) already described.
0.4 <d11 / fW <0.9 (10)
Meet. Here, d11 is the distance from the vertex of the most object-side surface of the first lens group Gr1 to the intersection P2 of the reflecting surface S2 of the reflecting optical element (prism) PRM and the optical axis OX.

In the zoom lens ZL of the second embodiment, in addition to the conditional expression (1), the conditional expression (11) already described.
−3.0 <r1 / d1 <−1.5 (11)
Meet. Here, r1 is the paraxial radius of curvature of the object-side optical surface S1 of the reflective optical element (prism) PRM, and d1 is from the object-side optical surface S1 to the image-side optical surface S3 of the reflective optical element PRM. The distance on the optical axis.

In the zoom lens ZL of the second embodiment, in addition to the conditional expression (1), the conditional expression (12) already described.
−3.0 <(r1 + r2) / (r1−r2) <− 0.5 (12)
Meet. Here, r1 is a paraxial curvature radius of the object-side optical surface S1 of the reflective optical element (prism) PRM, and r2 is a paraxial curvature radius of the image-side optical surface S3 of the reflective optical element PRM.

The imaging device 100 according to the first or second embodiment described above is an example of a configuration suitable for the present invention, and the present invention is not limited to this.

〔Example〕
Examples of the zoom lens of the present invention will be described below. Symbols used in each example are as follows.
f: Focal length of the entire zoom lens system Fno: F number 2Y: Diagonal length of the imaging surface of the solid-state imaging device R: Paraxial radius of curvature D: Spacing on the axial surface Nd: Refractive index νd of lens material with respect to d-line: Abbe of lens material Number β2: lateral magnification of the second lens group

In each embodiment, the surface described with “*” after each surface number (Surf.N) is a surface having an aspherical shape, and the aspherical shape has the apex of the surface as the origin and the optical axis direction. Is expressed by the following “Equation 1” where the height in the direction perpendicular to the optical axis is h. In addition, the symbol inf. Means infinity or ∞, and the symbol stop means aperture.
[Equation 1]

However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant

Specific examples of the zoom lens according to the present invention will be described below.
[Example 1]
The basic features of the zoom lens of Example 1 are as follows.
Zoom ratio = 2.85
Total lens length = 27.206

Table 1 shows lens data of Example 1. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using E (for example, 2.5E-02).
[Table 1]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 1615.221 0.500 1.92290 20.9 2.66
2 8.613 0.533 2.51
3 inf. 4.635 2.00070 25.5 2.49
4 inf.0.100 2.32
5 * 6.049 1.403 1.62260 58.2 2.28
6 * -7.670 d1 2.24
7 * -4.251 0.300 1.85130 40.1 1.24
8 * 4.134 0.532 1.20
9 -11.546 0.300 1.80420 46.5 1.26
10 6.679 0.010 1.51400 42.8 1.34
11 6.679 0.801 2.00270 19.3 1.34
12 -18.273 d2 1.44
13 (stop) inf. 0.000 1.53
14 * 4.365 1.049 1.68890 31.2 1.67
15 * -7.536 0.878 1.72
16 12.673 0.300 2.00270 19.3 1.73
17 3.363 0.010 1.51400 42.8 1.69
18 3.363 1.644 1.49700 81.6 1.69
19 -5.721 d3 1.79
20 * -46.018 0.350 1.90200 25.1 1.82
21 * 7.186 d4 1.81
22 * 4.549 2.000 1.54470 56.2 2.49
23 * 26.693 1.455 2.45
24 inf. 0.210 1.51680 64.2 2.32
25 inf. 0.500 2.32

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.41108E-03, A6 = -0.38586E-04,
A8 = 0.41053E-05, A10 = -0.84725E-06
6th page
K = 0.00000E + 00, A4 = 0.13828E-02, A6 = -0.58340E-04,
A8 = 0.34628E-05, A10 = -0.62759E-06
7th page
K = 0.00000E + 00, A4 = -0.79153E-03, A6 = 0.39983E-02,
A8 = -0.12259E-02, A10 = 0.14661E-03
8th page
K = 0.00000E + 00, A4 = -0.10227E-01, A6 = 0.44440E-02,
A8 = -0.12729E-02, A10 = 0.15039E-03
14th page
K = 0.00000E + 00, A4 = -0.26205E-02, A6 = -0.95860E-04,
A8 = -0.25407E-04, A10 = 0.13247E-04, A12 = -0.50479E-05
15th page
K = 0.00000E + 00, A4 = 0.25955E-02, A6 = -0.17352E-03,
A8 = -0.52299E-04, A10 = 0.23593E-04, A12 = -0.64025E-05
20th page
K = 0.00000E + 00, A4 = 0.16234E-01, A6 = -0.45553E-02,
A8 = 0.53692E-03, A10 = -0.12006E-04, A12 = -0.31404E-05
21st page
K = 0.00000E + 00, A4 = 0.17103E-01, A6 = -0.43207E-02,
A8 = 0.39979E-03, A10 = 0.26346E-04, A12 = -0.69795E-05
22nd page
K = 0.00000E + 00, A4 = 0.26716E-03, A6 = -0.32086E-03,
A8 = 0.20525E-04, A10 = 0.55244E-06, A12 = -0.42377E-06
23rd page
K = 0.00000E + 00, A4 = 0.24238E-02, A6 = -0.10550E-02,
A8 = 0.14196E-03, A10 = -0.17636E-04, A12 = 0.69310E-06

The focal length (f) of the entire system at each position (Po) 1 to 3 of the zoom lens of Embodiment 1 (F), F number (Fno), angle of view, diagonal length of imaging surface (2Y), group interval (d1 to d4) The lateral magnification (β2) of the second lens group is shown in Table 2 below. Note that Po = 1 is the wide-angle end, Po = 2 is the wide-angle end, Po = 2 is the middle, and Po = 3 is the telephoto end.
[Table 2]
Po f Fno angle of view 2Y
1 3.72 3.69 63.4 3.910
2 6.26 3.86 40.4 4.439
3 10.61 3.90 24.5 4.640

Po d1 d2 d3 d4
1 0.200 3.677 1.010 4.808
2 1.974 1.903 2.560 3.258
3 3.577 0.300 4.631 1.188

Data of each lens group of the zoom lens of Example 1 is shown in Table 3 below.
[Table 3]
Lens group Start surface Focal length (mm)
1 1 7.50
2 7 -2.66
3 13 4.26
4 20 -6.87
5 22 9.76

7A to 7C are sectional views of the zoom lens 11 according to the first embodiment. In Example 1 and the following examples, the reflective optical element PRM is represented as a parallel plate equivalent to the optical path length.
The zoom lens 11 of Example 1 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. . Here, the first lens group Gr1 includes a first lens L11 having a negative meniscus that is convex on the object side close to a plano-concave, a reflective optical element PRM that is a right-angle prism, and a positive second lens L12 that is biconvex. . The second lens group Gr2 includes a biconcave negative third lens L21, a biconcave negative fourth lens L22, and a biconvex positive fifth lens L23 which is cemented to the fourth lens L22. The third lens group Gr3 includes an aperture stop S, a biconvex positive sixth lens L31, a negative meniscus seventh lens L32 convex toward the object side, and a biconvex positive positive second lens. 8 lenses L33. The fourth lens group Gr4 includes a negative ninth lens L41 that is biconcave. The fifth lens group Gr5 includes a tenth lens L51 that is convex on the object side and has a positive meniscus. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric. In addition, the code | symbol F shows the parallel plate which assumed the optical low-pass filter, IR cut filter, the sealing glass of a solid-state image sensor, etc. Reference numeral I denotes an imaging surface that is a projection surface of the imaging device 51. The parallel plate F and the imaging surface I are the same in the second to thirteenth embodiments described below, and will not be described in the future. In the sectional view of the embodiment, the reflective optical element PRM is represented as a parallel plate equivalent to the optical path length. The display in which the reflective optical element PRM is expanded along the optical axis is the same in the following Examples 2 to 13, and will not be described in the future.

7A to 7C respectively show the positions of the zoom lens 11 of the first embodiment during the zoom operation. 7A is a cross-sectional view at the wide-angle end of the zoom lens 11, FIG. 7B is a cross-sectional view at the middle, and FIG. 7C is a cross-sectional view at the telephoto end.

8A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 11, and FIG. 8B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). FIG. 8C is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the telephoto end. In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

In the zoom lens 11 of Example 1, the second lens group Gr2 moves to the object side along the optical axis AX direction and the fourth lens group Gr4 moves to the optical axis AX during zooming from the wide-angle end to the telephoto end. Move to the object side along the direction. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the second lens L12, the third lens L21, and the ninth lens L41 are glass mold lenses, the tenth lens L51 is a plastic lens, and the other lenses are polished lenses made of a glass material.

[Example 2]
The basic features of the zoom lens of Example 2 are as follows.
Zoom ratio = 2.75
Total lens length = 17.00

Table 4 shows lens data of Example 2.
[Table 4]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 inf. 0.400 1.92290 20.9 1.84
2 4.550 0.824 1.64
3 inf. 2.553 2.00070 25.5 1.58
4 inf.0.198 1.55
5 * 4.288 1.074 1.69680 55.5 1.54
6 * -5.694 d1 1.45
7 -4.610 0.300 1.77250 49.6 0.91
8 1.790 0.114 0.80
9 1.764 0.794 1.92290 20.9 0.80
10 2.469 d2 0.65
11 (stop) inf. 0.100 0.57
12 * 3.055 0.837 1.59200 67.0 0.63
13 * -4.594 0.200 0.73
14 13.139 0.560 1.92290 20.9 0.76
15 6.650 0.961 1.49700 81.6 0.78
16 -4.633 d3 0.85
17 -4.539 0.350 1.92290 20.9 0.89
18 8.347 d4 0.95
19 * 3.977 0.776 1.54470 56.2 1.37
20 * 13.508 0.721 1.51
21 inf.0.145 1.51680 64.2 1.61
22 inf. 0.500 1.62

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.48281E-02, A6 = 0.53031E-03,
A8 = -0.18666E-03, A10 = -0.24116E-04
6th page
K = 0.00000E + 00, A4 = -0.15148E-02, A6 = 0.13168E-02,
A8 = -0.51716E-03, A10 = 0.32715E-04
12th page
K = 0.00000E + 00, A4 = -0.78007E-02, A6 = 0.17572E-01,
A8 = -0.55829E-01, A10 = 0.55601E-01
Side 13
K = 0.00000E + 00, A4 = 0.59768E-02, A6 = 0.18877E-01,
A8 = -0.44309E-01, A10 = 0.35932E-01
19th page
K = 0.00000E + 00, A4 = 0.36221E-03, A6 = -0.60671E-03,
A8 = -0.27850E-02, A10 = -0.11319E-02
20th page
K = 0.00000E + 00, A4 = 0.66471E-02, A6 = 0.93571E-02,
A8 = -0.11461E-01, A10 = 0.14583E-02

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group interval (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens of Example 2 The lateral magnification (β2) of the second lens group is shown in Table 5 below. In Example 2 and Examples 3 to 8 below, Po = 1 is the wide-angle end, Po = 2 is the wide-angle end, Po = 2 is intermediate, and Po = 3 is The fourth lens group Gr4 is at the inflection point, and Po = 4 is the telephoto end.
[Table 5]
Po f Fno angle of view 2Y
1 2.65 5.89 63.5 2.788
2 4.30 5.91 41.7 3.172
3 5.53 5.90 33.0 3.284
4 7.29 5.91 25.4 3.377

Po d1 d2 d3 d4 β2
1 0.200 2.863 1.133 1.399 -0.548
2 1.441 1.622 1.481 1.051 -0.793
3 2.017 1.046 1.555 0.976 -1.000
4 2.605 0.458 1.424 1.107 -1.363
Data for each lens group of the zoom lens of Example 2 is shown in Table 6 below.

[Table 6]
Lens group Start surface Focal length (mm)
1 1 4.72
2 7 -2.21
3 11 2.65
4 17 -3.15
5 19 10.06

9A to 9D are cross-sectional views of the zoom lens 12 according to the second embodiment. The zoom lens 12 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a plano-concave negative first lens L11, a reflective optical element PRM that is a right-angle prism, and a biconvex positive second lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes an aperture stop S, a biconvex positive fifth lens L31, a negative meniscus sixth lens L32 convex toward the object side, and a biconvex positive positive first lens. 7 lens L33. The fourth lens group Gr4 includes a biconcave negative eighth lens L41. The fifth lens group Gr5 includes a ninth lens L51 that is convex on the object side and has a positive meniscus. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 9A to 9D respectively show the positions of the zoom lens 12 of the second embodiment during the zoom operation. 9A is a cross-sectional view at the wide-angle end of the zoom lens 12, FIG. 9B is a cross-sectional view at the middle, and FIG. 9C shows that the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is the inflection point. FIG. 9D is a cross-sectional view at the telephoto end.

FIG. 10A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 12, and FIG. 10B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). . FIG. 11A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 12 when the fourth lens group Gr4 is located at the inflection point, and FIG. 11B is an aberration diagram at the telephoto end. (Spherical aberration, astigmatism, and distortion). In the aberration diagrams and the subsequent aberration diagrams, in the spherical aberration diagram, the solid line represents the d line and the dotted line represents the g line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional. It shall represent the image plane.

In zoom lens 12 of Example 2, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves to the object side along the optical axis AX direction, and the fourth lens group Gr4 moves in the optical axis AX direction. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. The second lens L12 and the fifth lens L31 are assumed to be glass mold lenses, the ninth lens L51 is assumed to be a plastic lens as described above, and the other lenses are assumed to be polished lenses made of a glass material.

Example 3
The basic features of the zoom lens of Example 3 are as follows.
Zoom ratio = 2.75
Total lens length = 18.00

Table 7 shows lens data of Example 3.
[Table 7]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 inf. 0.400 1.92290 20.9 1.96
2 4.967 0.797 1.75
3 inf. 2.907 2.00070 25.5 1.71
4 inf.0.178 1.67
5 * 4.506 1.082 1.69680 55.5 1.66
6 * -6.378 d1 1.58
7 -5.279 0.300 1.77250 49.6 0.98
8 1.881 0.133 0.86
9 1.882 0.791 1.92290 20.9 0.86
10 2.661 d2 0.71
11 (stop) inf. 0.100 0.61
12 * 3.372 0.831 1.59200 67.0 0.67
13 * -4.993 0.200 0.77
14 17.683 0.570 1.92290 20.9 0.80
15 9.302 0.988 1.49700 81.6 0.83
16 -4.051 d3 0.91
17 -5.676 0.350 1.92290 20.9 0.93
18 6.240 d4 0.97
19 * 3.858 0.802 1.54470 56.2 1.48
20 * 9.702 0.954 1.63
21 inf.0.145 1.51680 64.2 1.76
22 inf. 0.500 1.77

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.37157E-02, A6 = 0.25659E-03,
A8 = -0.24870E-04, A10 = -0.19994E-04,
6th page
K = 0.00000E + 00, A4 = -0.11513E-02, A6 = 0.88880E-03,
A8 = -0.24112E-03, A10 = 0.91950E-05,
12th page
K = 0.00000E + 00, A4 = -0.40904E-02, A6 = -0.27954E-02,
A8 = 0.32816E-02, A10 = 0.60791E-03
Side 13
K = 0.00000E + 00, A4 = 0.74030E-02, A6 = 0.40973E-02,
A8 = -0.76203E-02, A10 = 0.65724E-02
19th page
K = 0.00000E + 00, A4 = -0.27897E-02, A6 = -0.24593E-02,
A8 = -0.39032E-04, A10 = -0.94875E-03
20th page
K = 0.00000E + 00, A4 = -0.25151E-02, A6 = 0.71849E-02,
A8 = -0.64530E-02, A10 = 0.64658E-03

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group interval (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens of Embodiment 3 The lateral magnification (β2) of the second lens group is shown in Table 8 below.
[Table 8]
Po f Fno angle of view 2Y
1 2.88 5.88 63.5 3.03
2 4.68 5.91 41.7 3.451
3 5.91 5.91 33.6 3.565
4 7.92 5.91 25.4 3.671

Po d1 d2 d3 d4 β2
1 0.200 3.071 1.115 1.586 -0.557
2 1.544 1.727 1.417 1.285 -0.807
3 2.121 1.150 1.473 1.229 -1.000
4 2.813 0.458 1.338 1.364 -1.401

Data for each lens group of the zoom lens of Example 3 is shown in Table 9 below.
[Table 9]
Lens group Start surface Focal length (mm)
1 1 5.14
2 7 -2.42
3 11 2.76
4 17 -3.18
5 19 11.22

12A to 12D are sectional views of the zoom lens 13 according to the third embodiment. The zoom lens 13 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a plano-concave negative first lens L11, a reflective optical element PRM that is a right-angle prism, and a biconvex positive second lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes an aperture stop S, a biconvex positive fifth lens L31, a negative meniscus sixth lens L32 convex toward the object side, and a biconvex positive positive first lens. 7 lens L33. The fourth lens group Gr4 includes a biconcave negative eighth lens L41. The fifth lens group Gr5 includes a ninth lens L51 that is convex on the object side and has a positive meniscus. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

12A to 12D respectively show the positions during the zoom operation of the zoom lens 13 of the third embodiment. 12A is a cross-sectional view of the zoom lens 13 at the wide-angle end, FIG. 12B is a cross-sectional view in the middle, and FIG. 12C shows that the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is the inflection point. FIG. 12D is a cross-sectional view at the telephoto end.

FIG. 13A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 13, and FIG. 13B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). . 14A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 13 when the fourth lens group Gr4 is located at the inflection point, and FIG. 14B is an aberration diagram at the telephoto end. (Spherical aberration, astigmatism, and distortion). In the spherical aberration diagram, the solid line represents the d-line and the dotted line represents the g-line, and in the astigmatism diagram, the solid line represents the sagittal image plane and the dotted line represents the meridional image plane.

In zoom lens 13 of Example 3, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis AX direction, and the fourth lens group Gr4 moves in the optical axis AX direction. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. The second lens L12 and the fifth lens L31 are assumed to be glass mold lenses, the ninth lens L51 is assumed to be a plastic lens as described above, and the other lenses are assumed to be polished lenses made of a glass material.

Example 4
The basic features of the zoom lens of Example 4 are as follows.
Zoom ratio = 2.75
Total lens length = 17.86

Table 10 shows lens data of Example 4.
[Table 10]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -19.602 0.400 1.92290 20.9 1.85
2 5.389 0.706 1.72
3 inf. 3.005 2.00070 25.5 1.71
4 inf. 0.280 1.68
5 * 4.305 1.140 1.69680 55.5 1.67
6 * -5.267 d1 1.58
7 -5.967 0.300 1.74330 49.2 1.00
8 1.831 0.105 0.87
9 1.833 0.794 1.92290 20.9 0.87
10 2.494 d2 0.71
11 (stop) inf. 0.100 0.72
12 * 2.986 0.956 1.62260 58.2 0.80
13 * -3.626 0.200 0.87
14 -10.163 0.383 1.91080 35.3 0.88
15 4.785 1.000 1.49710 81.6 0.91
16 * -3.130 d3 1.00
17 13.020 0.350 1.92290 20.9 1.09
18 2.813 d4 1.08
19 * 5.123 1.041 1.54470 56.2 1.71
20 * 18.909 0.500 1.80
21 inf.0.145 1.51680 64.2 1.81
22 inf. 0.500 1.81

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.28526E-02, A6 = 0.93367E-04,
A8 = 0.19768E-04, A10 = -0.78856E-05
6th page
K = 0.00000E + 00, A4 = 0.18130E-02, A6 = 0.48779E-03,
A8 = -0.10381E-03, A10 = 0.61860E-05
12th page
K = 0.00000E + 00, A4 = -0.40130E-02, A6 = -0.31911E-02,
A8 = 0.19773E-02, A10 = -0.52894E-02
Side 13
K = 0.00000E + 00, A4 = 0.15525E-01, A6 = -0.81300E-02,
A8 = 0.58816E-02, A10 = -0.65406E-02
16th page
K = 0.00000E + 00, A4 = 0.26182E-0, A6 = 0.78142E-02,
A8 = -0.54881E-02, A10 = 0.31592E-02
19th page
K = 0.00000E + 00, A4 = 0.14293E-01, A6 = -0.13939E-02,
A8 = -0.13408E-02, A10 = 0.16611E-03
20th page
K = 0.00000E + 00, A4 = 0.14190E-01, A6 = 0.37589E-02,
A8 = -0.47443E-02, A10 = 0.58791E-03

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens of Example 4 Table 11 below shows the lateral magnification (β2) of the second lens group.
[Table 11]
Po f Fno angle of view 2Y
1 2.88 4.77 63.4 3.022
2 3.91 4.74 49.1 3.351
3 4.67 4.74 41.8 3.481
4 7.92 4.80 25.4 3.635

Po d1 d2 d3 d4 β2
1 0.200 2.958 1.832 0.960 -0.754
2 1.027 2.131 1.956 0.836 -1.000
3 1.469 1.689 1.908 0.884 -1.211
4 2.651 0.507 0.935 1.857 -2.788

Data for each lens group of the zoom lens of Example 4 is shown in Table 12 below.
[Table 12]
Lens group Start surface Focal length (mm)
1 1 4.25
2 7 -2.53
3 11 3.15
4 17 -3.95
5 19 12.57

15A to 15D are cross-sectional views of the zoom lens 14 according to the fourth embodiment. The zoom lens 14 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a biconcave negative first lens L11, a reflective optical element PRM that is a right angle prism, and a biconvex positive lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes an aperture stop S, a biconvex positive fifth lens L31, a biconcave negative sixth lens L32, and a biconvex positive seventh lens L33 which is cemented to the sixth lens L32. Including. The fourth lens group Gr4 includes an eighth lens L41 that is convex on the object side and has a negative meniscus. The fifth lens group Gr5 includes a ninth lens L51 that is convex on the object side and has a positive meniscus. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 15A to 15D respectively show the positions of the zoom lens 14 of the fourth embodiment during the zoom operation. 15A is a cross-sectional view of the zoom lens 14 at the wide-angle end, and FIG. 15B is a cross-sectional view when the lateral magnification of the second lens group Gr is −1 and the fourth lens group Gr4 is at the position of the inflection point. FIG. 15C is a cross-sectional view in the middle, and FIG. 15D is a cross-sectional view at the telephoto end.

FIG. 16A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 14, and FIG. 16B is an aberration diagram when the fourth lens group Gr4 is at the position of the inflection point (spherical surface). Aberration, astigmatism, and distortion). FIG. 17A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 14 in the middle, and FIG. 17B is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the telephoto end. It is.

In the zoom lens 14 of Example 4, the second lens group Gr2 moves toward the object side along the optical axis AX direction and the fourth lens group Gr4 moves in the optical axis AX direction during zooming from the wide-angle end to the telephoto end. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the second lens L12, the fifth lens L31, and the seventh lens L33 are glass mold lenses, the ninth lens L51 is a plastic lens as described above, and the other lenses are polished lenses made of a glass material.

Example 5
The basic features of the zoom lens of Example 5 are as follows.
Zoom ratio = 2.75
Total lens length = 18.46

Table 13 shows lens data of Example 5.
[Table 13]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -72.480 0.400 1.92290 20.9 1.85
2 3.394 0.597 1.59
3 inf. 3.532 1.84670 23.8 1.56
4 inf. 0.215 1.61
5 * 4.759 1.101 1.69680 55.5 1.63
6 * -4.759 d1 1.58
7 -5.312 0.300 1.77250 49.6 0.96
8 1.855 0.105 0.85
9 1.884 0.830 1.92290 20.9 0.86
10 2.888 d2 0.71
11 (stop) inf. 0.100 0.61
12 * 2.853 0.907 1.59200 67.0 0.67
13 * -3.634 0.200 0.76
14 2613.514 0.519 1.90370 31.3 0.78
15 6.586 1.000 1.49700 81.6 0.80
16 -4.413 d3 0.87
17 -4.312 0.350 1.92290 20.9 0.90
18 4.801 d4 0.96
19 * 3.518 1.163 1.54470 56.2 1.62
20 * -26.618 0.777 1.71
21 inf.0.145 1.51680 64.2 1.78
22 inf. 0.500 1.79

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.41298E-02, A6 = 0.21093E-03,
A8 = 0.28408E-05, A10 = -0.15437E-04
6th page
K = 0.00000E + 00, A4 = -0.24169E-03, A6 = 0.65122E-03,
A8 = -0.13066E-03, A10 = 0.19137E-05
12th page
K = 0.00000E + 00, A4 = -0.85593E-02, A6 = -0.86054E-02,
A8 = 0.21907E-01, A10 = -0.19551E-01
Side 13
K = 0.00000E + 00, A4 = 0.98757E-02, A6 = 0.60379E-04,
A8 = 0.64594E-03, A10 = -0.68783E-03
19th page
K = 0.00000E + 00, A4 = 0.16187E-02, A6 = 0.67840E-02,
A8 = -0.40896E-02, A10 = 0.42660E-03
20th page
K = 0.00000E + 00, A4 = -0.26767E-02, A6 = 0.19645E-01,
A8 = -0.84720E-02, A10 = 0.88423E-03

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group spacing (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens of Example 5 The lateral magnification (β2) of the second lens group is shown in Table 14 below.
[Table 14]
Po f Fno angle of view 2Y
1 2.30 5.87 75.5 2.854
2 3.81 5.91 50.1 3.393
3 4.51 5.91 43.1 3.502
4 6.34 5.91 31.4 3.664

Po d1 d2 d3 d4 β2
1 0.200 3.154 1.138 1.228 -0.577
2 1.632 1.722 1.384 0.983 -0.854
3 2.068 1.287 1.409 0.958 -1.000
4 2.910 0.444 1.246 1.120 -1.495

Data for each lens group of the zoom lens of Example 5 is shown in Table 15 below.
[Table 15]
Lens group Start surface Focal length (mm)
1 1 4.20
2 7 -2.54
3 11 2.74
4 17 -2.42
5 19 5.78

18A to 18D are cross-sectional views of the zoom lens 15 according to the fifth embodiment. The zoom lens 15 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a biconcave negative first lens L11, a reflective optical element PRM that is a right angle prism, and a biconvex positive lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes an aperture stop S, a biconvex positive fifth lens L31, a negative meniscus sixth lens L32 convex toward the object side, and a biconvex positive positive first lens. 7 lens L33. The fourth lens group Gr4 includes a biconcave negative eighth lens L41. The fifth lens group Gr5 includes a biconvex positive ninth lens L51. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 18A to 18D show the positions of the zoom lens 15 of Example 5 during the zoom operation. 18A is a cross-sectional view at the wide-angle end of the zoom lens 15, FIG. 18B is a cross-sectional view at the middle, and FIG. 18C shows that the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is at the inflection point. FIG. 18D is a cross-sectional view at the telephoto end.

19A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 15, and FIG. 19B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). . 20A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 15 when the fourth lens group Gr4 is located at the inflection point, and FIG. 20B is an aberration diagram at the telephoto end. (Spherical aberration, astigmatism, and distortion).

In zoom lens 15 of Example 5, when zooming from the wide angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis AX direction, and the fourth lens group Gr4 moves in the optical axis AX direction. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. The second lens L12 and the fifth lens L31 are assumed to be glass mold lenses, the ninth lens L51 is assumed to be a plastic lens as described above, and the other lenses are assumed to be polished lenses made of a glass material.

Example 6
The basic features of the zoom lens of Example 6 are as follows.
Zoom ratio = 2.75
Lens total length = 17.40

Table 16 shows lens data of Example 6.
[Table 16]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -27.291 0.400 1.92290 20.9 1.77
2 3.660 0.512 1.54
3 inf. 3.241 2.00070 25.5 1.51
4 inf. 0.206 1.51
5 * 4.538 1.106 1.72920 54.7 1.52
6 * -4.487 d1 1.45
7 -4.928 0.300 1.80420 46.5 0.91
8 1.611 0.166 0.79
9 1.679 0.850 1.92290 20.9 0.81
10 2.388 d2 0.65
11 (stop) inf. 0.100 0.57
12 * 2.750 0.733 1.59200 67.0 0.63
13 * 27.209 0.200 0.72
14 4.209 0.565 1.92290 20.9 0.78
15 3.336 0.600 1.49710 81.6 0.79
16 * -2.206 d3 0.83
17 -3.070 0.350 1.92290 20.9 0.82
18 5.704 d4 0.88
19 * 5.342 1.200 1.54470 56.2 1.55
20 * -5.908 0.500 1.61
21 inf.0.145 1.51680 64.2 1.65
22 inf. 0.500 1.66

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.40754E-02, A6 = 0.67267E-03,
A8 = -0.21081E-03, A10 = 0.59078E-05
6th page
K = 0.00000E + 00, A4 = 0.10818E-02, A6 = 0.11510E-02,
A8 = -0.40970E-03, A10 = 0.38374E-04
12th page
K = 0.00000E + 00, A4 = -0.11250E-02, A6 = -0.44687E-01,
A8 = 0.84551E-01, A10 = -0.10073E + 00
Side 13
K = 0.00000E + 00, A4 = 0.16776E-01, A6 = -0.45450E-01,
A8 = 0.73218E-01, A10 = -0.84438E-01
16th page
K = 0.00000E + 00, A4 = 0.18660E-01, A6 = 0.27293E-01,
A8 = -0.38968E-01, A10 = 0.34324E-01
19th page
K = 0.00000E + 00, A4 = 0.23972E-01, A6 = 0.50889E-04,
A8 = -0.17046E-02, A10 = 0.13415E-03
20th page
K = 0.00000E + 00, A4 = 0.23192E-01, A6 = 0.15762E-01,
A8 = -0.81507E-02, A10 = 0.82781E-03

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group interval (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens according to the sixth exemplary embodiment. The lateral magnification (β2) of the second lens group is shown in Table 17 below.
[Table 17]
Po f Fno angle of view 2Y
1 2.12 5.88 75.4 2.623
2 3.42 5.92 51.2 3.13
3 5.12 5.92 35.5 3.342
4 5.83 5.91 31.4 3.383

Po d1 d2 d3 d4 β2
1 0.200 2.727 1.165 1.635 -0.499
2 1.354 1.572 1.422 1.378 -0.701
3 2.210 0.717 1.541 1.259 -1.000
4 2.467 0.460 1.525 1.276 -1.147

Data for each lens group of the zoom lens of Example 6 is shown in Table 18 below.
[Table 18]
Lens group Start surface Focal length (mm)
1 1 3.89
2 7 -2.01
3 11 2.32
4 17 -2.12
5 19 5.35

21A to 21D are cross-sectional views of the zoom lens 16 according to the sixth embodiment. The zoom lens 16 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a biconcave negative first lens L11, a reflective optical element PRM that is a right angle prism, and a biconvex positive lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 is cemented to the aperture stop S, the fifth lens L31 that is convex toward the object side and has a positive meniscus, the sixth lens L32 that is convex toward the object side and is a negative meniscus, and is biconvex. And a positive seventh lens L33. The fourth lens group Gr4 includes a biconcave negative eighth lens L41. The fifth lens group Gr5 includes a biconvex positive ninth lens L51. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 21A to 21D respectively show the positions of the zoom lens 16 of the sixth embodiment during the zoom operation. 21A is a cross-sectional view at the wide-angle end, FIG. 21B is a cross-sectional view in the middle, and FIG. 21C is when the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is at the position of the inflection point. FIG. 21D is a cross-sectional view at the telephoto end.

FIG. 22A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 16, and FIG. 22B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). . FIG. 23A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 16 when the fourth lens group Gr4 is located at the inflection point, and FIG. 23B is an aberration diagram at the telephoto end. (Spherical aberration, astigmatism, and distortion).

In zoom lens 16 of Embodiment 6, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis AX direction, and the fourth lens group Gr4 moves in the optical axis AX direction. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the second lens L12, the fifth lens L31, and the seventh lens L33 are glass mold lenses, the ninth lens L51 is a plastic lens as described above, and the other lenses are polished lenses made of a glass material.

Example 7
The basic features of the zoom lens of Example 7 are as follows.
Zoom ratio = 3.79
Total lens length = 20.77

Table 19 shows lens data of Example 7.
[Table 19]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -9.982 0.400 1.92290 20.9 1.60
2 5.629 0.347 1.46
3 inf. 4.000 2.00070 25.5 1.45
4 inf.0.193 1.53
5 * 3.854 1.193 1.69680 55.5 1.56
6 * -5.037 d1 1.45
7 -4.721 0.300 1.77250 49.6 0.88
8 1.785 0.100 0.78
9 1.688 0.752 1.92290 20.9 0.79
10 2.135 d2 0.65
11 (stop) inf. 0.388 0.68
12 * 4.505 1.500 1.58310 59.5 0.83
13 * -2.988 0.701 0.99
14 -84.279 0.436 1.90370 31.3 1.01
15 5.068 1.000 1.49710 81.6 1.02
16 * -4.308 d3 1.08
17 7.306 0.350 1.92290 20.9 1.04
18 2.188 d4 1.00
19 * 7.672 1.024 1.82080 42.7 1.72
20 * -176.084 0.500 1.70
21 inf.0.145 1.51680 64.2 1.65
22 inf. 0.500 1.64

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.31725E-02, A6 = 0.16967E-02,
A8 = -0.59429E-03, A10 = 0.17835E-03
6th page
K = 0.00000E + 00, A4 = 0.33225E-02, A6 = 0.23920E-02,
A8 = -0.93272E-03, A10 = 0.26782E-03
12th page
K = 0.00000E + 00, A4 = 0.18965E-02, A6 = -0.16867E-01,
A8 = 0.23323E-01, A10 = -0.17636E-01
Side 13
K = 0.00000E + 00, A4 = 0.19015E-01, A6 = -0.11705E-01,
A8 = 0.93750E-02, A10 = -0.47765E-02
16th page
K = 0.00000E + 00, A4 = -0.13219E-01, A6 = 0.12882E-01,
A8 = -0.84575E-02, A10 = 0.27360E-02
19th page
K = 0.00000E + 00, A4 = -0.14364E-01, A6 = 0.17931E-01,
A8 = -0.49196E-02, A10 = 0.44608E-03
20th page
K = 0.00000E + 00, A4 = -0.43247E-01, A6 = 0.35363E-01,
A8 = -0.10091E-01, A10 = 0.93992E-03

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens of Example 7 The lateral magnification (β2) of the second lens group is shown in Table 20 below.
[Table 20]
Po f Fno angle of view 2Y
1 2.66 5.93 63.4 2.612
2 4.61 5.74 39.1 3.115
3 5.07 5.75 35.8 3.162
4 10.06 6.07 18.5 3.196

Po d1 d2 d3 d4 β2
1 0.200 3.223 1.812 1.704 -0.605
2 1.541 1.882 2.247 1.269 -1.000
3 1.731 1.693 2.229 1.286 -1.102
4 2.901 0.523 0.890 2.626 -2.950

Data for each lens group of the zoom lens of Example 7 is shown in Table 21 below.
[Table 21]
Lens group Start surface Focal length (mm)
1 1 3.68
2 7 -2.06
3 11 3.38
4 17 -3.50
5 19 8.98

24A to 24D are cross-sectional views of the zoom lens 17 according to the seventh embodiment. The zoom lens 17 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a biconcave negative first lens L11, a reflective optical element PRM that is a right angle prism, and a biconvex positive lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 includes an aperture stop S, a biconvex positive fifth lens L31, a biconcave negative sixth lens L32, and a biconvex positive seventh lens L33 which is cemented to the sixth lens L32. Including. The fourth lens group Gr4 includes an eighth lens L41 that is convex on the object side and has a negative meniscus. The fifth lens group Gr5 includes a biconvex positive ninth lens L51. Both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 24A to 24D respectively show the positions of the zoom lens 17 of the seventh embodiment during the zoom operation. 24A is a cross-sectional view at the wide-angle end of the zoom lens 17, and FIG. 24B is a cross-sectional view when the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is at the position of the inflection point. FIG. 24C is a cross-sectional view in the middle, and FIG. 24D is a cross-sectional view at the telephoto end.

FIG. 25A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 17, and FIG. 25B shows the zoom lens 17 when the fourth lens group Gr4 is at the position of the inflection point. It is an aberration diagram (spherical aberration, astigmatism, and distortion). FIG. 26A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 17 in the middle, and FIG. 26B is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the telephoto end. It is.

In zoom lens 17 of Example 7, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis AX direction, and the fourth lens group Gr4 moves in the optical axis AX direction. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the second lens L12, the fifth lens L31, the seventh lens L33, and the ninth lens L51 are glass mold lenses, and the other lenses are polished lenses made of a glass material.

Example 8
The basic features of the zoom lens of Example 8 are as follows.
Zoom ratio = 2.75
Total lens length = 18.00

Table 22 shows lens data of Example 8.
[Table 22]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 inf. 0.400 1.92290 20.9 1.97
2 5.088 0.783 1.82
3 inf. 2.934 2.00070 25.5 1.81
4 inf. 0.235 1.78
5 * 5.284 1.045 1.69680 55.5 1.78
6 * -6.146 d1 1.72
7 -5.061 0.300 1.77250 49.6 1.00
8 2.073 0.100 0.89
9 2.011 0.761 1.92290 20.9 0.89
10 2.831 d2 0.75
11 * 2.920 0.803 1.59200 67.0 0.72
12 * -9.474 0.100 0.65
13 (stop) inf. 0.100 0.63
14 7.668 0.579 1.92290 20.9 0.65
15 5.610 0.999 1.49700 81.6 0.68
16 -4.135 d3 0.77
17 -2.732 0.350 1.92290 20.9 0.88
18 22.089 d4 0.98
19 * 3.089 1.012 1.54470 56.2 1.49
20 * 13.430 0.838 1.61
21 inf.0.145 1.51680 64.2 1.73
22 inf. 0.500 1.74

[Aspheric coefficient]
5th page
K = 0.00000E + 00, A4 = -0.23275E-02, A6 = -0.68227E-03,
A8 = 0.30376E-03, A10 = -0.72796E-04
6th page
K = 0.00000E + 00, A4 = -0.40166E-03, A6 = -0.12179E-03,
A8 = 0.10224E-03, A10 = -0.44363E-04
11th page
K = 0.00000E + 00, A4 = 0.26378E-02, A6 = -0.16616E-01,
A8 = 0.28238E-01, A10 = -0.15720E-01
12th page
K = 0.00000E + 00. A4 = 0.11633E-01, A6 = 0.25915E-02,
A8 = -0.21637E-01, A10 = 0.33638E-01
19th page
K = 0.00000E + 00, A4 = -0.75651E-02, A6 = -0.30701E-02,
A8 = 0.10501E-02, A10 = -0.52350E-03
20th page
K = 0.00000E + 00, A4 = -0.18528E-02, A6 = -0.69966E-03,
A8 = -0.77555E-03, A10 = -0.86546E-04

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), group interval (d1 to d4) of the entire system at each position (Po) 1 to 4 of the zoom lens of Example 8 The horizontal magnification (β2) of the second lens group is shown in Table 23 below.
[Table 23]
Po f Fno angle of view 2Y
1 2.88 5.71 63.5 3.034
2 4.68 5.88 41.7 3.440
3 7.55 5.92 26.6 3.612
4 7.92 5.92 25.4 3.626

Po d1 d2 d3 d4 β2
1 0.200 3.127 1.204 1.485 -0.483
2 1.638 1.689 1.597 1.092 -0.666
3 2.900 0.427 1.846 0.843 -1.000
4 3.020 0.307 1.844 0.845 -1.050

Data for each lens group of the zoom lens of Example 8 is shown in Table 24 below.
[Table 24]
Lens group Start surface Focal length (mm)
1 1 5.76
2 7 -2.52
3 11 2.71
4 17 -2.62
5 19 7.12

27A to 27D are cross-sectional views of the zoom lens 18 according to the eighth embodiment. The zoom lens 18 includes, in order from the object side, a first lens group Gr1, a second lens group Gr2, a third lens group Gr3, a fourth lens group Gr4, and a fifth lens group Gr5. Here, the first lens group Gr1 includes a biconcave negative first lens L11, a reflective optical element PRM that is a right angle prism, and a biconvex positive lens L12. The second lens group Gr2 includes a biconcave negative third lens L21 and a positive meniscus fourth lens L22 convex toward the object side. The third lens group Gr3 is cemented to the aperture stop S, the fifth lens L31 that is convex toward the object side and has a positive meniscus, the sixth lens L32 that is convex toward the object side and is a negative meniscus, and is biconvex. And a positive seventh lens L33. The fourth lens group Gr4 includes a biconcave negative eighth lens L41. The fifth lens group Gr5 includes a biconvex positive ninth lens L51. The fifth lens group Gr5 is a single lens made of plastic, and both surfaces of the fifth lens group Gr5 are aspheric.

FIGS. 27A to 27D respectively show positions at the time of zoom operation of the zoom lens 18 of the eighth embodiment. 27A is a cross-sectional view at the wide-angle end of the zoom lens 18, FIG. 27B is a cross-sectional view at the middle, and FIG. 27C shows that the lateral magnification of the second lens group Gr2 is −1 and the fourth lens group Gr4 is the inflection point. FIG. 27D is a cross-sectional view at the telephoto end.

28A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) at the wide-angle end of the zoom lens 18, and FIG. 28B is an intermediate aberration diagram (spherical aberration, astigmatism, and distortion aberration). . FIG. 29A is an aberration diagram (spherical aberration, astigmatism, and distortion aberration) of the zoom lens 18 when the fourth lens group Gr4 is located at the inflection point, and FIG. 29B is an aberration diagram at the telephoto end. (Spherical aberration, astigmatism, and distortion).

In the zoom lens 18 of Example 8, the second lens group Gr2 moves toward the object side along the optical axis AX direction and the fourth lens group Gr4 moves in the optical axis AX direction during zooming from the wide-angle end to the telephoto end. It is possible to perform zooming by changing the position or interval of each lens unit by moving along a convex locus that moves to the object side after moving to the image side. The other lens groups Gr1, Gr3, Gr5 are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. The second lens L12 and the fifth lens L31 are assumed to be glass mold lenses, the ninth lens L51 is assumed to be a plastic lens as described above, and the other lenses are assumed to be polished lenses made of a glass material.

Example 9
The basic features of the zoom lens of Example 9 are as follows.
Zoom ratio = 2.82
Total lens length = 25.100
d11 = 2.100

Table 25 shows lens data and the like of Example 9.
[Table 25]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -10.111 4.600 2.00070 25.5 2.53
2 inf.0.100 2.40
3 * 10.441 1.147 1.88200 37.2 2.38
4 * -10.253 d1 2.35
5 -6.656 0.300 2.00070 25.5 1.34
6 3.699 0.400 1.24
7 * 7.467 0.668 1.68890 31.2 1.31
8 * 10.721 d2 1.38
9 8.131 1.024 1.84670 23.8 1.56
10 -8.446 0.100 1.53
11 (stop) inf. 0.000 1.47
12 7.383 1.305 1.49700 81.6 1.49
13 -3.437 0.010 1.51400 42.8 1.51
14 -3.437 0.300 2.00070 25.5 1.52
15 -65.303 0.400 1.61
16 * 14.370 1.131 1.73080 40.5 1.75
17 * -5.142 d3 1.81
18 * -20.187 0.350 2.00180 19.3 1.55
19 * 6.450 d4 1.55
20 * 5.532 1.600 1.54470 56.2 2.11
21 * 37.637 0.729 2.32
22 inf.0.145 1.51680 64.2 2.30
23 inf. 0.500 2.30

[Aspheric coefficient]
Third side
K = 0.00000E + 00, A4 = -0.10960E-03, A6 = -0.38020E-04,
A8 = 0.35369E-05, A10 = -0.45724E-06
4th page
K = 0.00000E + 00, A4 = 0.63937E-03, A6 = -0.46204E-04,
A8 = 0.33466E-05, A10 = -0.39700E-06
7th page
K = 0.00000E + 00, A4 = -0.83277E-03, A6 = 0.58392E-06,
A8 = 0.63622E-03, A10 = -0.13337E-03
8th page
K = 0.00000E + 00, A4 = -0.73516E-02, A6 = 0.25395E-03,
A8 = 0.24029E-03, A10 = -0.45712E-04
16th page
K = 0.00000E + 00, A4 = -0.23031E-02, A6 = 0.24298E-03,
A8 = 0.49785E-04, A10 = 0.10095E-04
17th page
K = 0.00000E + 00, A4 = 0.72386E-03, A6 = 0.23746E-03,
A8 = -0.13042E-04, A10 = 0.19488E-04
18th page
K = 0.00000E + 00, A4 = 0.48545E-02, A6 = -0.86515E-03,
A8 = 0.29946E-05, A10 = 0.12751E-04
19th page
K = 0.00000E + 00, A4 = 0.35400E-02, A6 = -0.66012E-03,
A8 = -0.10272E-03, A10 = 0.29294E-04
20th page
K = 0.00000E + 00, A4 = -0.56514E-02, A6 = -0.92814E-03,
A8 = -0.22747E-04, A10 = -0.11583E-04
21st page
K = 0.00000E + 00, A4 = -0.18743E-02, A6 = -0.17367E-02,
A8 = 0.31721E-04, A10 = 0.51719E-05

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens of Example 9. ) Is shown in Table 26 below. In Example 9 and Examples 10 to 13 below, Po = 1 is the wide-angle end, Po = 2 is the wide-angle end, Po = 2 is intermediate, and Po = 3 is The telephoto end.
[Table 26]
Po f Fno angle of view 2Y
1 3.73 3.77 63.3 3.915
2 6.33 3.92 39.9 4.593
3 10.50 3.86 23.9 4.600

Po d1 d2 d3 d4
1 0.254 3.951 1.048 5.039
2 2.208 1.997 2.287 3.800
3 3.905 0.300 4.483 1.604

Data for each lens group of the zoom lens of Example 9 is shown in Table 27 below.
[Table 27]
Lens group Start surface Focal length (mm)
1 1 8.95
2 5 -2.49
3 9 3.75
4 18 -4.85
5 20 11.70

30 and 31A to 31C are sectional views of the lens of Example 9. FIG. In the figure, symbol GR1 is a first lens group having positive refractive power, symbol GR2 is a second lens group having negative refractive power, symbol GR3 is a third lens group having positive refractive power, and symbol GR4 is negative. A fourth lens group having refractive power, symbol GR5, indicates a fifth lens group having positive refractive power. The first lens group Gr1 includes, in order from the object side, a reflective optical element (for example, a right angle prism) PRM that can bend a light beam from the object side at a right angle, and a biconvex positive lens L1. Has positive refractive power. The second lens group Gr2 includes, in order from the object side, a biconcave negative lens L3, and a positive lens L3 that is convex on the object side and concave on the image side, and has a negative refractive power as a whole. ing. The third lens group Gr3 includes a biconvex positive lens L4, an aperture stop S, a cemented lens in which the positive lens L5 and the negative lens L6 are combined, and a biconvex positive lens L7, and has a positive refractive power as a whole. Have. The fourth lens group Gr4 includes only a biconcave negative lens L8, and has a negative refracting power as a whole. The fifth lens group Gr5 is composed of only a positive lens L9 that is convex near the optical axis and concave on the peripheral side, and has a positive refracting power as a whole. In the ninth embodiment, the reflective optical element PRM has a curvature on the object side surface, the image side surface is a flat surface, and the entire reflective optical element has a negative refractive power.

Here, FIG. 30 is a cross-sectional view at the wide-angle end. 31A to 31C and the subsequent cross-sectional views, the reflective optical element PRM is represented as a rotationally symmetric single lens having an equivalent optical path length. In FIG. 30, the distance from the vertex P1 of the surface S1 closest to the object side of the first lens group to the intersection P2 of the reflecting surface S2 of the reflecting optical element PRM and the optical axis OX is defined as d11.

FIG. 31A is a cross-sectional view at the wide-angle end. FIG. 31B is a cross-sectional view in the middle. FIG. 31C is a cross-sectional view at the telephoto end. FIGS. 32A to 32C are aberration diagrams of Example 9 (spherical aberration, astigmatism, distortion aberration). FIG. 32A is an aberration diagram at the wide-angle end, FIG. 32B is an aberration diagram at the middle, and FIG. It is an aberration diagram at the telephoto end.

In the zoom lens of Example 9, the second lens group Gr2 moves toward the object side along the optical axis direction and the fourth lens group Gr4 moves along the optical axis direction during zooming from the wide-angle end to the telephoto end. The zooming can be performed by moving to the image side and changing the interval between the lens groups. The remaining lens groups are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the first lens L1, the third lens L3, the seventh lens L7, and the eighth lens L8 are glass mold lenses, the ninth lens L9 is a plastic lens, and the other lenses are polished lenses made of a glass material. .

Example 10
The basic features of the zoom lens of Example 10 are as follows.
Zoom ratio = 2.82
Total lens length = 26.568
d11 = 2.164

Table 28 shows lens data of Example 10.
[Table 28]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -10.494 4.568 2.00070 25.5 2.53
2 inf. 0.100 2.33
3 * 8.893 1.223 1.89140 37.5 2.30
4 * -10.795 d1 2.26
5 -7.204 0.300 2.00270 19.3 1.28
6 4.050 0.400 1.19
7 13.645 0.300 1.69470 56.7 1.20
8 5.694 0.331 1.23
9 * 19.634 0.614 1.91180 23.8 1.31
10 * 49.792 d2 1.38
11 (stop) inf. 0.000 1.45
12 * 9.457 1.040 1.64280 31.8 1.50
13 * -5.510 0.300 1.66
14 18.277 0.600 1.93600 26.7 1.80
15 7.353 0.010 1.51400 42.8 1.84
16 7.353 1.919 1.51080 66.9 1.84
17 -4.147 d3 2.02
18 * -14.050 0.388 1.99710 19.8 1.71
19 * 9.386 d4 1.72
20 * 6.982 1.600 1.54470 56.2 2.27
21 * -10.268 1.088 2.45
22 inf.0.145 1.51680 64.2 2.33
23 inf. 0.500 2.32

[Aspheric coefficient]
Third side
K = 0.00000E + 00, A4 = -0.43577E-03, A6 = -0.30162E-04,
A8 = 0.33086E-05, A10 = -0.11091E-05
4th page
K = 0.00000E + 00, A4 = 0.39604E-03, A6 = -0.16685E-04,
A8 = -0.23403E-05, A10 = -0.59115E-06
9th page
K = 0.00000E + 00, A4 = -0.95226E-03, A6 = 0.86306E-03,
A8 = 0.68317E-04, A10 = -0.24042E-04
10th page
K = 0.00000E + 00, A4 = -0.52177E-02, A6 = 0.77604E-03,
A8 = -0.12347E-03, A10 = 0.19858E-04
12th page
K = 0.00000E + 00, A4 = -0.28717E-02, A6 = 0.19360E-03,
A8 = -0.77449E-04, A10 = 0.72804E-05
Side 13
K = 0.00000E + 00, A4 = 0.24747E-02, A6 = 0.61242E-04,
A8 = -0.91543E-05, A10 = -0.13467E-05
18th page
K = 0.00000E + 00, A4 = 0.10902E-01, A6 = -0.44332E-02,
A8 = 0.97140E-03, A10 = -0.10456E-03
19th page
K = 0.00000E + 00, A4 = 0.10164E-01, A6 = -0.44281E-02,
A8 = 0.92159E-03, A10 = -0.93717E-04
20th page
K = 0.00000E + 00, A4 = -0.19191E-02, A6 = -0.11818E-02,
A8 = 0.84505E-04, A10 = -0.15870E-04
21st page
K = 0.00000E + 00, A4 = 0.18688E-02, A6 = -0.14733E-02,
A8 = 0.84655E-04, A10 = -0.45999E-05

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens of Example 10. ) Is shown in Table 29 below.
[Table 29]
Po f Fno angle of view 2Y
1 3.75 3.91 63.1 3.918
2 6.26 4.01 40.4 4.571
3 10.57 3.90 23.9 4.600

Po d1 d2 d3 d4
1 0.239 3.533 1.862 5.509
2 1.919 1.852 3.299 4.072
3 3.471 0.300 5.762 1.609

Data for each lens group of the zoom lens of Example 10 is shown in Table 30 below.
[Table 30]
Lens group Start surface Focal length (mm)
1 1 7.84
2 5 -2.24
3 11 3.96
4 18 -5.60
5 20 7.89

33A to 33C are sectional views of the lens of Example 10. FIG. In the figure, symbol GR1 is a first lens group having positive refractive power, symbol GR2 is a second lens group having negative refractive power, symbol GR3 is a third lens group having positive refractive power, and symbol GR4 is negative. A fourth lens group having refractive power, symbol GR5, indicates a fifth lens group having positive refractive power. The first lens group Gr1 includes, in order from the object side, a reflective optical element (for example, a right angle prism) PRM that can bend a light beam from the object side at a right angle, and a biconvex positive lens L1. Has positive refractive power. The second lens group Gr2 includes, in order from the object side, a biconcave negative lens L3, a positive lens L3 that is convex on the object side, a concave lens on the image side, and a positive lens L4 that is convex on the object side. It has a negative refractive power as a whole. The third lens group Gr3 includes an aperture stop S, a biconvex positive lens L5, and a cemented lens obtained by combining a negative lens L6 and a positive lens L7, and has a positive refractive power as a whole. The fourth lens group Gr4 includes only a biconcave negative lens L8, and has a negative refracting power as a whole. The fifth lens group Gr5 is composed of only a positive lens L9 that is convex near the optical axis and concave on the peripheral side, and has a positive refracting power as a whole. In the tenth embodiment, the reflective optical element PRM has a curvature on the object side surface, the image side surface is a flat surface, and the reflective optical element as a whole has a negative refractive power.

Here, FIG. 33A is a cross-sectional view at the wide-angle end. FIG. 33B is a cross-sectional view in the middle. FIG. 33C is a cross-sectional view at the telephoto end. 34A to 34C are aberration diagrams of Example 10 (spherical aberration, astigmatism, distortion), FIG. 34A is an aberration diagram at the wide-angle end, FIG. 34B is an aberration diagram at the middle, and FIG. It is an aberration diagram at the telephoto end.

In the zoom lens of Example 10, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis direction, and the fourth lens group Gr4 moves along the optical axis direction. The zooming can be performed by moving to the side and changing the interval between the lens groups. The remaining lens groups are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the first lens L1, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are glass mold lenses, the ninth lens L9 is a plastic lens, and the other lenses are polished lenses made of a glass material. .

Example 11
The basic features of the zoom lens of Example 11 are as follows.
Zoom ratio = 2.82
Total lens length = 25.050
d11 = 2.148

Table 31 shows lens data of Example 11.
[Table 31]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -9.961 4.550 2.00070 25.5 2.53
2 inf.0.100 2.37
3 * 10.323 1.228 1.88200 37.2 2.35
4 * -9.397 d1 2.33
5 -6.406 0.300 2.00070 25.5 1.31
6 3.667 0.400 1.21
7 * 9.867 0.635 1.68890 31.2 1.29
8 * 11.746 d2 1.37
9 8.571 0.991 1.84670 23.8 1.56
10 -9.243 0.100 1.53
11 (stop) inf .0.000 1.48
12 6.369 1.437 1.49700 81.6 1.51
13 -3.697 0.010 1.51400 42.8 1.55
14 -3.697 0.375 2.00070 25.5 1.55
15 -34.142 0.400 1.65
16 * 10.195 1.163 1.73080 40.5 1.79
17 * -5.738 d3 1.83
18 * 14.303 0.383 2.00180 19.3 1.49
19 * 3.003 0.506 1.43
20 * 7.607 0.750 1.63470 23.9 1.63
21 * 6.956 d4 1.74
22 * 5.375 1.467 1.54470 56.2 2.18
23 * -18.889 1.000 2.37
24 inf.0.145 1.51680 64.2 2.32
25 inf. 0.500 2.32

[Aspheric coefficient]
Third side
K = 0.00000E + 00, A4 = -0.27028E-03, A6 = -0.76400E-04,
A8 = 0.83622E-05, A10 = -0.17252E-05
4th page
K = 0.00000E + 00, A4 = 0.59880E-03, A6 = -0.68370E-04,
A8 = 0.29705E-05, A10 = -0.11278E-05
7th page
K = 0.00000E + 00, A4 = -0.11419E-02, A6 = -0.19745E-03,
A8 = 0.82802E-03, A10 = -0.17741E-03
8th page
K = 0.00000E + 00, A4 = -0.83739E-02, A6 = -0.22834E-03,
A8 = 0.49311E-03, A10 = -0.10217E-03
16th page
K = 0.00000E + 00, A4 = -0.19071E-02, A6 = 0.15789E-03,
A8 = 0.64990E-04, A10 = 0.69421E-05
17th page
K = 0.00000E + 00, A4 = 0.17301E-02, A6 = 0.11160E-03,
A8 = 0.26892E-04, A10 = 0.14370E-04
18th page
K = 0.00000E + 00, A4 = -0.37648E-02, A6 = -0.12153E-03,
A8 = 0.45622E-03, A10 = -0.10454E-03
19th page
K = 0.00000E + 00, A4 = 0.33590E-02, A6 = -0.72571E-03,
A8 = -0.51473E-04, A10 = 0.13698E-04
20th page
K = 0.00000E + 00, A4 = 0.20352E-01, A6 = -0.30235E-02,
A8 = -0.46768E-03, A10 = 0.34028E-04
21st page
K = 0.00000E + 00, A4 = 0.54506E-02, A6 = -0.19600E-02,
A8 = -0.33545E-03, A10 = -0.14945E-05
22nd page
K = 0.00000E + 00, A4 = -0.47779E-02, A6 = -0.67116E-03,
A8 = -0.65050E-04, A10 = -0.12766E-04
23rd page
K = 0.00000E + 00, A4 = -0.24340E-02, A6 = -0.86129E-03,
A8 = -0.78757E-04, A10 = 0.66324E-05

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens according to the eleventh embodiment. ) Is shown in Table 32 below.
[Table 32]
Po f Fno angle of view 2Y
1 3.73 3.77 63.3 3.914
2 6.23 3.89 40.4 4.600
3 10.51 3.86 23.9 4.600

Po d1 d2 d3 d4
1 0.243 3.686 0.925 3.756
2 2.028 1.902 1.950 2.731
3 3.630 0.300 3.665 1.017

Data for each lens group of the zoom lens of Example 11 is shown in Table 33 below.
[Table 33]
Lens group Start surface Focal length (mm)
1 1 8.25
2 5 -2.33
3 9 3.58
4 18 -3.64
5 22 7.85

35A to 35C are sectional views of the lens of Example 11. FIG. In the figure, symbol GR1 is a first lens group having positive refractive power, symbol GR2 is a second lens group having negative refractive power, symbol GR3 is a third lens group having positive refractive power, and symbol GR4 is negative. A fourth lens group having refractive power, symbol GR5, indicates a fifth lens group having positive refractive power. The first lens group Gr1 includes, in order from the object side, a reflective optical element (for example, a right angle prism) PRM that can bend a light beam from the object side at a right angle, and a biconvex positive lens L1. Has positive refractive power. The second lens group Gr2 includes, in order from the object side, a biconcave negative lens L3, and a positive lens L3 that is convex on the object side and concave on the image side, and has a negative refractive power as a whole. ing. The third lens group Gr3 includes a biconvex positive lens L4, an aperture stop S, a cemented lens in which the positive lens L5 and the negative lens L6 are combined, and a biconvex positive lens L7, and has a positive refractive power as a whole. Have. The fourth lens group Gr4 includes a negative meniscus lens L8 and a positive meniscus lens L9 that are convex on the object side, and has a negative refracting power as a whole. The fifth lens group Gr5 is composed only of a positive lens L10 that is convex on the object side near the optical axis and concave on the peripheral side, and has a positive refracting power as a whole. In the eleventh embodiment, the reflecting optical element PRM has a curvature on the object side surface, the image side surface is a flat surface, and the entire reflecting optical element has a negative refractive power.

Here, FIG. 35A is a cross-sectional view at the wide-angle end. FIG. 35B is a cross-sectional view in the middle. FIG. 35C is a cross-sectional view at the telephoto end. 36A to 36C are aberration diagrams of Example 11 (spherical aberration, astigmatism, distortion), FIG. 36A is an aberration diagram at the wide-angle end, FIG. 36B is an aberration diagram at the middle, and FIG. It is an aberration diagram at the telephoto end.

In the zoom lens of Example 11, when zooming from the wide-angle end to the telephoto end, the second lens group Gr2 moves toward the object side along the optical axis direction, and the fourth lens group Gr4 moves along the optical axis direction. The zooming can be performed by moving to the side and changing the interval between the lens groups. The remaining lens groups are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. The first lens L1, the third lens L3, the seventh lens L7, and the eighth lens L8 are glass molded lenses, the ninth lens L9 and the tenth lens L10 are plastic lenses, and the other lenses are polished lenses made of a glass material. Is assumed.

Example 12
The basic features of the zoom lens of Example 12 are as follows.
Zoom ratio = 2.81
Total lens length = 26.027
d11 = 2.013

Table 34 shows lens data of Example 12.
[Table 34]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -7.949 4.449 2.00060 25.5 2.43
2 -17.005 0.100 2.42
3 * 14.001 1.117 1.88300 40.8 2.35
4 * -11.304 d1 2.32
5 -6.923 0.300 1.91150 24.1 1.46
6 2.815 0.400 1.33
7 * 5.780 0.868 1.61680 32.8 1.37
8 * 10.834 d2 1.35
9 7.848 1.090 1.72740 26.0 1.59
10 -6.753 0.100 1.55
11 (stop) inf. 0.000 1.47
12 7.048 1.475 1.49700 81.6 1.50
13 -2.953 0.010 1.51400 42.8 1.51
14 -2.953 0.400 1.88010 33.0 1.51
15 24.028 0.317 1.63
16 * 15.055 1.288 1.59940 64.6 1.73
17 * -3.909 d3 1.88
18 * -13.737 0.350 1.89150 33.7 1.69
19 * 10.390 d4 1.70
20 * 5.409 1.200 1.54470 56.2 2.18
21 * 42.951 1.308 2.33
22 inf.0.145 1.51680 64.2 2.29
23 inf. 0.500 2.29

[Aspheric coefficient]
Third side
K = 0.00000E + 00, A4 = -0.24490E-03, A6 = -0.62198E-04,
A8 = 0.11569E-05, A10 = -0.96599E-06
4th page
K = 0.00000E + 00, A4 = 0.30753E-03, A6 = -0.70682E-04,
A8 = -0.53219E-06, A10 = -0.62392E-06
7th page
K = 0.00000E + 00, A4 = 0.31181E-02, A6 = 0.12635E-02,
A8 = 0.29864E-03, A10 = 0.75260E-05
8th page
K = 0.00000E + 00, A4 = -0.72844E-02, A6 = 0.10195E-02,
A8 = -0.12965E-03, A10 = 0.86898E-04
16th page
K = 0.00000E + 00, A4 = -0.53889E-02, A6 = 0.86730E-04,
A8 = -0.51410E-04, A10 = 0.73181E-05
17th page
K = 0.00000E + 00, A4 = -0.13856E-02, A6 = 0.27003E-04,
A8 = -0.48975E-04, A10 = 0.46212E-05
18th page
K = 0.00000E + 00, A4 = 0.77865E-02, A6 = -0.18266E-02,
A8 = 0.21790E-03, A10 = -0.14081E-04
19th page
K = 0.00000E + 00, A4 = 0.69664E-02, A6 = -0.17211E-02,
A8 = 0.16360E-03, A10 = -0.87225E-05
20th page
K = 0.00000E + 00, A4 = -0.45755E-02, A6 = -0.14050E-02,
A8 = 0.84100E-04, A10 = -0.22026E-04
21st page
K = 0.00000E + 00, A4 = -0.11739E-02, A6 = -0.18800E-02,
A8 = 0.98179E-04, A10 = -0.55378E-05

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens of Example 12. ) Is shown in Table 35 below.
[Table 35]
Po f Fno angle of view 2Y
1 3.74 3.77 63.1 3.916
2 6.24 3.92 40.4 4.559
3 10.52 3.87 23.9 4.600

Po d1 d2 d3 d4
1 0.262 3.682 1.080 5.586
2 2.023 1.921 2.580 4.086
3 3.644 0.300 4.967 1.700

Data for each lens group of the zoom lens of Example 12 is shown in Table 36 below.
[Table 36]
Lens group Start surface Focal length (mm)
1 1 7.73
2 5 -2.43
3 9 4.16
4 18 -6.59
5 20 11.23

37A to 37C are sectional views of the lens of Example 12. FIG. In the figure, symbol GR1 is a first lens group having positive refractive power, symbol GR2 is a second lens group having negative refractive power, symbol GR3 is a third lens group having positive refractive power, and symbol GR4 is negative. A fourth lens group having refractive power, symbol GR5, indicates a fifth lens group having positive refractive power. The first lens group Gr1 includes, in order from the object side, a reflective optical element (for example, a right angle prism) PRM that can bend a light beam from the object side at a right angle, and a biconvex positive lens L1. Has positive refractive power. The second lens group Gr2 includes, in order from the object side, a biconcave negative lens L3, and a positive lens L3 that is convex on the object side and concave on the image side, and has a negative refractive power as a whole. ing. The third lens group Gr3 includes a biconvex positive lens L4, an aperture stop S, a cemented lens in which the positive lens L5 and the negative lens L6 are combined, and a biconvex positive lens L7, and has a positive refractive power as a whole. Have. The fourth lens group Gr4 includes only a biconcave negative lens L8, and has a negative refracting power as a whole. The fifth lens group Gr5 is composed of only a positive lens L9 that is convex near the optical axis and concave on the peripheral side, and has a positive refracting power as a whole. In the twelfth embodiment, the reflective optical element PRM has an object side surface and a curvature on the object side surface, and the entire reflective optical element has a negative refractive power.

Here, FIG. 37A is a cross-sectional view at the wide-angle end. FIG. 36B is a cross-sectional view in the middle. FIG. 36C is a cross-sectional view at the telephoto end. 38A to 38C are aberration diagrams of Example 12 (spherical aberration, astigmatism, distortion aberration), FIG. 38A is an aberration diagram at the wide-angle end, FIG. 38B is an aberration diagram at the middle, and FIG. It is an aberration diagram at the telephoto end.

In the zoom lens of Example 12, the second lens group Gr2 moves toward the object side along the optical axis direction and the fourth lens group Gr4 moves along the optical axis direction during zooming from the wide-angle end to the telephoto end. The zooming can be performed by moving to the side and changing the interval between the lens groups. The remaining lens groups are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the first lens L1, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are glass mold lenses, the ninth lens L9 is a plastic lens, and the other lenses are polished lenses made of a glass material. .

Example 13
The basic features of the zoom lens of Example 13 are as follows.
Zoom ratio = 2.82
Total lens length = 27.938
d11 = 2.462

Table 37 shows lens data of Example 13.
[Table 37]
[Curvature radius, surface spacing, etc.]
Surf.N R (mm) D (mm) Nd νd Effective radius (mm)
1 -14.559 5.102 1.97920 25.2 2.90
2 44.854 0.264 2.54
3 * 9.145 1.302 1.88050 40.9 2.50
4 * -10.790 d1 2.46
5 -5.961 0.300 1.90820 25.3 1.20
6 2.922 0.400 1.16
7 * 5.970 0.969 1.63290 31.4 1.27
8 * 7.748 d2 1.37
9 10.959 1.144 1.82370 23.7 1.56
10 -6.576 0.100 1.55
11 (stop) inf. 0.000 1.49
12 9.086 1.461 1.49700 81.6 1.51
13 -2.884 0.010 1.51400 42.8 1.56
14 -2.884 0.400 1.90700 25.8 1.57
15 793.304 0.324 1.72
16 * 13.064 1.425 1.59740 34.8 1.86
17 * -3.709 d3 2.02
18 * -14.435 0.350 1.91730 22.4 1.70
19 * 8.925 d4 1.70
20 * 7.212 1.600 1.54470 56.2 2.22
21 * -24.062 1.289 2.41
22 inf.0.145 1.51680 64.2 2.33
23 inf. 0.500 2.32

[Aspheric coefficient]
Third side
K = 0.00000E + 00, A4 = -0.11713E-03, A6 = -0.41006E-04,
A8 = 0.50921E-05, A10 = -0.55248E-06
4th page
K = 0.00000E + 00, A4 = 0.71117E-03, A6 = -0.48604E-04,
A8 = 0.45164E-05, A10 = -0.48376E-06
7th page
K = 0.00000E + 00, A4 = -0.11579E-02, A6 = 0.18412E-02,
A8 = 0.49967E-04, A10 = 0.23581E-04
8th page
K = 0.00000E + 00, A4 = -0.11057E-01, A6 = 0.14590E-02,
A8 = -0.21963E-03, A10 = 0.52616E-04
16th page
K = 0.00000E + 00, A4 = -0.41863E-02, A6 = 0.62874E-04,
A8 = -0.47591E-04, A10 = 0.23398E-05
17th page
K = 0.00000E + 00, A4 = 0.29941E-03, A6 = -0.26626E-04,
A8 = -0.17350E-04, A10 = -0.11563E-05
18th page
K = 0.00000E + 00, A4 = 0.72938E-02, A6 = -0.21388E-02,
A8 = 0.34117E-03, A10 = -0.22061E-04
19th page
K = 0.00000E + 00, A4 = 0.64788E-02, A6 = -0.21802E-02,
A8 = 0.34068E-03, A10 = -0.23607E-04
20th page
K = 0.00000E + 00, A4 = -0.39661E-02, A6 = -0.98144E-03,
A8 = 0.51138E-04, A10 = -0.10790E-04
21st page
K = 0.00000E + 00, A4 = -0.17003E-02, A6 = -0.12746E-02,
A8 = 0.91386E-04, A10 = -0.40861E-05

The focal length (f), F number (Fno), field angle, imaging surface diagonal length (2Y), and group interval (d1 to d4) of the entire system at each position (Po) 1 to 3 of the zoom lens of Example 13. ) Is shown in Table 38 below.
[Table 38]
Po f Fno angle of view 2Y
1 3.74 3.77 63.1 3.917
2 6.35 3.93 39.8 4.600
3 10.55 3.87 23.9 4.600

Po d1 d2 d3 d4
1 0.284 3.630 1.080 5.860
2 2.064 1.849 2.610 4.330
3 3.608 0.306 5.290 1.650

Data for each lens group of the zoom lens of Example 13 is shown in Table 39 below.
[Table 39]
Lens group Start surface Focal length (mm)
1 1 8.41
2 5 -2.19
3 9 4.03
4 18 -5.97
5 20 10.37

39A to 39C are sectional views of the lens of Example 13. FIG. In the figure, symbol GR1 is a first lens group having positive refractive power, symbol GR2 is a second lens group having negative refractive power, symbol GR3 is a third lens group having positive refractive power, and symbol GR4 is negative. A fourth lens group having refractive power, symbol GR5, indicates a fifth lens group having positive refractive power. The first lens group Gr1 includes, in order from the object side, a reflective optical element (for example, a right angle prism) PRM that can bend a light beam from the object side at a right angle, and a biconvex positive lens L1. Has positive refractive power. The second lens group Gr2 includes, in order from the object side, a biconcave negative lens L3, and a positive lens L3 that is convex on the object side and concave on the image side, and has a negative refractive power as a whole. ing. The third lens group Gr3 includes a biconvex positive lens L4, an aperture stop S, a cemented lens in which the positive lens L5 and the negative lens L6 are combined, and a biconvex positive lens L7, and has a positive refractive power as a whole. Have. The fourth lens group Gr4 includes only a biconcave negative lens L8, and has a negative refracting power as a whole. The fifth lens group Gr5 is composed of only a positive lens L9 that is convex near the optical axis and concave on the peripheral side, and has a positive refracting power as a whole. The reflective optical element PRM has a curvature on the object side surface and the object side surface in the thirteenth embodiment, and has a negative refractive power in the entire reflective optical element.

Here, FIG. 39A is a cross-sectional view at the wide-angle end. FIG. 39B is a cross-sectional view in the middle. FIG. 39C is a cross-sectional view at the telephoto end. 40A to 40C are aberration diagrams of Example 13 (spherical aberration, astigmatism, distortion), FIG. 40A is an aberration diagram at the wide-angle end, FIG. 40B is an aberration diagram at the middle, and FIG. It is an aberration diagram at the telephoto end.

In the zoom lens of Example 13, the second lens group Gr2 moves toward the object side along the optical axis direction and the fourth lens group Gr4 moves along the optical axis direction during zooming from the wide-angle end to the telephoto end. The zooming can be performed by moving to the side and changing the interval between the lens groups. The remaining lens groups are fixed during zooming. Further, focusing from infinity to a finite distance can be performed by moving the fourth lens group Gr4. It is assumed that the first lens L1, the fourth lens L4, the fifth lens L5, and the eighth lens L8 are glass mold lenses, the ninth lens L9 is a plastic lens, and the other lenses are polished lenses made of a glass material. .

Table 40 below summarizes the values of Examples 1 to 15 corresponding to the conditional expressions (1) to (12) for reference.
[Table 40]

In the above, the present invention has been described based on the embodiments and examples, but the present invention is not limited to the above-described embodiments and the like.

For example, by using a plastic material in which inorganic particles are dispersed in the production of a plastic lens such as the lenses L51 and L9 (or L10) of the fifth lens group of Examples 1 to 13, the zoom lens 10 and the entire ZL system It is possible to further suppress the image point position fluctuation at the time of temperature change.

Recently, it has been found that by mixing inorganic fine particles in a plastic material, the temperature change of the plastic material can be reduced. In detail, when fine particles are mixed with a transparent plastic material in general, light scattering occurs and the transmittance decreases, so that it was difficult to use as an optical material. By making it smaller than the wavelength, it is possible to substantially prevent scattering. The refractive index of the plastic material decreases with increasing temperature, but the refractive index of inorganic particles increases with increasing temperature. Therefore, it is possible to make almost no change in the refractive index by using these temperature dependencies so as to cancel each other. Specifically, by dispersing inorganic particles having a maximum length of 20 nanometers or less in a plastic material as a base material, a plastic material with extremely low temperature dependency of the refractive index is obtained. For example, by dispersing fine particles of niobium oxide (Nb ₂ O ₅ ) in acrylic, the refractive index change due to temperature change can be reduced. In the present invention, the entire zoom lens system is obtained by using a plastic material in which such inorganic particles are dispersed in a plastic lens such as the lenses L51 and L9 (or L10) of the fifth lens group in Examples 1 to 13. It is possible to further suppress the image point position fluctuation at the time of temperature change.

For the production of plastic lenses such as the lenses L51 and L9 (or L10) of the fifth lens group in Examples 1 to 13, an energy curable resin may be used.

In recent years, as a method for mounting an image pickup apparatus at a low cost and in large quantities, a reflow process (heating process) is performed on a substrate on which solder is previously potted while an IC chip or other electronic component and an optical element are placed on the substrate. A technique has been proposed in which an electronic component and an optical element are simultaneously mounted on a substrate by melting the substrate. In order to perform mounting using such a reflow process, it is necessary to heat the optical element together with the electronic components to about 200 to 260 ° C. Under such a high temperature, a lens using a thermoplastic resin is not suitable. There is a problem that the optical performance deteriorates due to thermal deformation or discoloration. As one of the methods for solving such a problem, a technology has been proposed that uses a glass mold lens having excellent heat resistance and achieves both miniaturization and optical performance in a high temperature environment. The cost is generally higher than the lens used. Therefore, by using an energy curable resin as the material of the zoom lens (specifically, for example, the ninth lens L51), it is exposed to a higher temperature than a lens using a thermoplastic resin such as polycarbonate or polyolefin. Therefore, it is effective for the reflow process, is easier to manufacture than a glass mold lens, and is inexpensive, and it is possible to achieve both low cost and mass productivity of an imaging apparatus incorporating a zoom lens. The energy curable resin refers to both a thermosetting resin and an ultraviolet curable resin.

It should be noted that the present invention is not limited to the examples described in the specification, and that other examples and modifications are included in the art based on the examples and ideas described in the present specification. It is obvious to For example, even when a dummy lens having substantially no power is further provided, it is within the scope of the present invention.

Claims

From the object side,
A first lens group having a positive refractive power;
A second lens group having negative refractive power;
A third lens group having positive refractive power;
A fourth lens group having negative refractive power;
A zoom lens that includes a fifth lens group having positive refractive power and performs zooming,
The first lens group includes a reflective optical element that bends the optical path by reflection;
During zooming from the wide-angle end to the telephoto end, the first and fifth lens groups are fixed,
The second lens group moves to the image side;
A zoom lens that satisfies the following conditional expression.
0.8 <f3 / fW <1.4 (1)
However,
f3: focal length of the third lens group fW: focal length of the entire system at the wide-angle end
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.2 <f1 / fT <1.0 (2)
However,
f1: focal length of the first lens unit fT: focal length of the entire system at the telephoto end
The zoom lens according to claim 1, wherein the reflective optical element reflects a light beam on an inner surface and satisfies the following conditional expression.
1.80 <nprm <2.20 (3)
However,
nprm: refractive index of the reflective optical element
The zoom lens according to claim 1, wherein the reflective optical element reflects a light beam on an inner surface and satisfies the following conditional expression.
1.0 ≦ d1aPRM / dPRM <1.6 (4)
However,
d1aPRM: distance on the optical axis from the most object side surface of the first lens group to the image side surface of the reflective optical element dPRM: on the optical axis from the object side surface of the reflective optical element to the image side surface distance
The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
−1.5 <f4 / (fW × fT) 1/2 <−0.5 (5)
However,
f4: focal length of the fourth lens group fW: focal length of the entire system at the wide angle end fT: focal length of the entire system at the telephoto end
2. The zoom lens according to claim 1, wherein the first lens group includes an optical element having a negative refractive power closest to the object side, and satisfies the following conditional expression.
1.0 <| f1a / fW | <6.0 (6)
However,
f1a: focal length of the optical element closest to the object side in the first lens group fW: focal length of the entire system at the wide-angle end
The zoom lens according to claim 1, wherein the fourth lens group moves to the image side upon zooming from the wide-angle end to the telephoto end.
The zoom lens according to claim 7, wherein the reflective optical element is a prism, has substantially no refractive power, and the reflective surface is substantially flat.
2. The zoom lens according to claim 1, wherein upon zooming from the wide-angle end to the telephoto end, the fourth lens group moves toward the object side after moving toward the image side, and satisfies the following conditional expression.
−0.8 <β2W <−0.4 (7)
-3.0 <β2T <-1.0 (8)
However,
β2W: Lateral magnification at the wide-angle end of the second lens group β2T: Lateral magnification at the telephoto end of the second lens group
The zoom lens according to claim 9, wherein the reflective optical element has substantially no refractive power.
The zoom lens according to claim 10, wherein the reflective optical element is a prism, and the most object side surface and the reflective surface of the prism are substantially flat.
The zoom lens according to claim 9, wherein the following conditional expression is satisfied.
1.5 <m2 / m4 <12.0 (9)
However,
m2: Maximum moving amount of the second lens group at zooming from the wide-angle end to the telephoto end m4: Maximum moving amount of the fourth lens group at zooming from the wide-angle end to the telephoto end
The zoom lens according to claim 1, wherein the reflective optical element is disposed closest to the object side and has negative refractive power.
The zoom lens according to claim 13, wherein the most object side surface of the reflective optical element is a concave surface.
The zoom lens according to claim 13, wherein the fourth lens group moves toward the image side upon zooming from the wide-angle end to the telephoto end.
The zoom lens according to claim 13, wherein the following condition is satisfied.
0.4 <d11 / fW <0.9 (10)
However,
d11: Distance from the vertex of the most object-side surface of the first lens group to the intersection of the reflecting surface of the reflecting optical element and the optical axis fW: Focal length of the entire zoom lens system at the wide angle end
The zoom lens according to claim 13, wherein the following condition is satisfied.
−3.0 <r1 / d1 <−1.5 (11)
However,
r1: Paraxial radius of curvature of the object-side optical surface of the reflective optical element d1: Distance on the optical axis from the object-side optical surface to the image-side optical surface of the reflective optical element
The zoom lens according to claim 13, wherein the following conditional expression is satisfied.
−3.0 <(r1 + r2) / (r1−r2) <− 0.5 (12)
However,
r1: Paraxial radius of curvature of the optical surface on the object side of the reflective optical element r2: Paraxial radius of curvature of the optical surface on the image side of the reflective optical element
The zoom lens according to claim 1, wherein the zoom lens performs focusing by moving the fourth lens group.
2. The zoom lens according to claim 1, wherein the third lens group does not move in the optical axis direction at the time of zooming and focusing.
The zoom lens according to claim 1, wherein the fifth lens group does not move in the optical axis direction when focused.
The zoom lens according to claim 1, wherein the third lens group includes at least two lenses having positive refractive power.
The zoom lens according to claim 1, wherein an aperture stop is disposed in the third lens group.
The zoom lens according to claim 1, wherein the fifth lens group is a single lens made of plastic, and at least one surface of the fifth lens group is an aspherical surface.
The zoom lens according to claim 1, further comprising a lens having substantially no power.
An image pickup apparatus comprising: the zoom lens according to any one of claims 1 to 25; and an image pickup device that photoelectrically converts an image formed on an image pickup surface by the zoom lens.
A portable terminal comprising the imaging device according to claim 26 and a display unit for displaying an image.