JP2024042622A - Zoom lens, image capturing device having the same, and image capturing system - Google Patents

Abstract

To provide an ultra wide-angle zoom lens which is compact and offers high optical performance over an entire object distance range.SOLUTION: A zoom lens B0 comprises, in order from the object side to the image side, a first lens group B1 having negative refractive power, and a rear group BR comprising multiple lens groups and having positive refractive power as a whole, and is configured such that distances between adjacent lens groups change while zooming from the wide-angle end to the telephoto end. The rear group comprises a lens group Fp having positive refractive power, at least two lens groups having positive refractive power, and a lens group Fn having negative refractive power arranged in order from the object side to the image side, where the lens group Fp and the lens group Fn move while shifting focus from infinity to a close distance. An input pupil position ENPw of the zoom lens at the wide-angle end and a focal length fw of the zoom lens at the wide-angle end satisfy a given conditional expression.SELECTED DRAWING: Figure 1

Description

The present invention relates to a zoom lens, and is suitable for digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, surveillance cameras, and the like.

As an imaging optical system, an imaging lens with a half angle of view of more than 50 degrees at the wide-angle end is called an ultra-wide-angle lens, and among these, a fast lens with an F value of 2.8 or less has a wide angle of view and short shutter speed. Suitable for taking pictures of starry skies and dark places. Such an ultra-wide-angle lens is required to have high resolution performance that suppresses spherical aberration and sagittal flare over a short distance from an infinite subject. Particularly in zoom lenses, there has been a problem in that it is difficult to reduce the size of the lens while suppressing variations in aberrations from the wide-angle end to the telephoto end.

As an ultra-wide-angle zoom lens, Patent Document 1 discloses a first lens group with negative refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power, which are arranged in order from the object side to the image side. A zoom lens is disclosed that includes a lens group and a fourth lens group with positive refractive power. In the zoom lens disclosed in Patent Document 1, the second lens group and the third lens group move toward the image side during focusing in order to improve resolution performance from an infinite object to a short distance.

Further, Patent Document 2 discloses a zoom lens having a larger diameter than the zoom lens of Patent Document 1. The zoom lens of Patent Document 2 includes a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, a fourth lens group with positive refractive power, and a negative refractive power. It consists of a fifth lens group with refractive power. In the zoom lens disclosed in Patent Document 2, a portion of the second lens group and a portion of the fifth lens group move during focusing in order to improve resolution performance from an infinite object to a short distance.

JP2016-75741A International Publication 2021/039695

However, the zoom lens disclosed in Patent Document 1 has a large F value and cannot sufficiently reduce aberration fluctuations during zooming due to an increase in aperture. The zoom lens of Patent Document 2 reduces aberration fluctuations during zooming by having multiple groups compared to the zoom lens of Patent Document 1, but there is a need for a wider angle and a smaller size.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ultra-wide-angle zoom lens that is compact and provides high optical performance over the entire object distance range.

A zoom lens according to one aspect of the present invention includes a first lens group with negative refractive power and a plurality of lens groups arranged in order from the object side to the image side, and has a rear group with positive refractive power as a whole. The zoom lens is a zoom lens in which the distance between adjacent lens groups changes during zooming from a wide-angle end to a telephoto end, and the rear group includes a lens group Fp with positive refractive power arranged in order from the object side to the image side. and at least two lens groups having a positive refractive power and a lens group Fn having a negative refractive power, the lens group Fp and the lens group Fn move during focusing from infinity to a close distance, and the lens group Fn moves at the wide-angle end. When the entrance pupil position of the zoom lens is ENPw, and the focal length of the zoom lens at the wide-angle end is fw,
1.0<ENPw/fw<3.0
It is characterized by satisfying the following conditional expression.

Other objects and features of the present invention are described in the following embodiments.

According to the present invention, it is possible to obtain an ultra-wide-angle zoom lens that is compact and provides high optical performance over the entire object distance range.

1 is a cross-sectional view of the zoom lens of Example 1. FIG. FIG. 3 is an aberration diagram of the zoom lens of Example 1 at the wide-angle end (A) and the telephoto end (B) when focusing at infinity. FIG. 2 is an aberration diagram of the zoom lens of Example 1 at the wide-angle end (A) and at the telephoto end (B) when focusing on a close range. 3 is a cross-sectional view of a zoom lens according to Example 2. FIG. FIG. 4 is an aberration diagram of the zoom lens of Example 2 at the wide-angle end (A) and the telephoto end (B) when focusing at infinity. FIGS. 3A and 3B are aberration diagrams of the zoom lens of Example 2 at the wide-angle end (A) and the telephoto end (B) when focusing on a close range. FIG. 11 is a cross-sectional view of a zoom lens according to a third embodiment. FIG. 7 is an aberration diagram of the zoom lens of Example 3 at (A) the wide-angle end and (B) the telephoto end when focusing at infinity. FIG. 7 is an aberration diagram of the zoom lens of Example 3 at the wide-angle end (A) and at the telephoto end (B) when focusing on a close range. FIG. 1 is a schematic diagram of an imaging device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a zoom lens of the present invention, an imaging device having the same, and an imaging system will be described based on the accompanying drawings.

1, 4, and 7 are cross-sectional views of the zoom lenses B0 of Examples 1 to 3, respectively, in a state where the lens is focused at infinity at the wide-angle end (infinity focus state). The zoom lens B0 of each embodiment is used in optical equipment including imaging devices and interchangeable lenses, such as digital video cameras, digital still cameras, broadcast cameras, silver halide film cameras, and surveillance cameras.

In each cross-sectional view, the left side is the object side, and the right side is the image side. The zoom lens B0 of each example includes a plurality of lens groups. The lens group in this specification is a component of the zoom lens B0 that is composed of one or more lenses. In the zoom lens B0 of each embodiment, the distance between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. Furthermore, the lens group may include an aperture stop.

In each cross-sectional view, Bi represents the i-th lens group (i is a natural number) counted from the object side among the lens groups included in the zoom lens B0. BR is a rear group that includes all lens groups arranged closer to the image side than the first lens group B1.

SP is an aperture stop. FP is a flare cut stop. IP is an image plane, and when the zoom lens B0 of each embodiment is used as the photographing optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is disposed thereon. When the zoom lens B0 of each embodiment is used as the photographing optical system of a silver halide film camera, a photosensitive surface equivalent to the film surface is placed on the image plane IP. Fi (i = n, p) indicates the lens group that moves when focusing.

The solid arrows shown in the cross-sectional views of each lens are simplified representations of the loci of movement of each lens group during zooming from the wide-angle end to the telephoto end. Note that in this specification, the wide-angle end and the telephoto end refer to zoom positions when each lens group is mechanically positioned at both ends of a movable range on the optical axis. Further, the arrows related to focus shown in each lens cross-sectional view are simplified representations of movement trajectories of the lens group during focusing from infinity to close range.

FIG. 2, FIG. 5, and FIG. 8 are aberration diagrams of the zoom lenses B0 of Examples 1 to 3 when focusing on infinity, respectively. 3, FIG. 6, and FIG. 9 are aberration diagrams of the zoom lenses B0 of Examples 1 to 3 when focusing on a close distance, respectively. In each aberration diagram, (A) is an aberration diagram at the wide-angle end, and (B) is an aberration diagram at the telephoto end.

In the spherical aberration diagram, Fno is the F number, which indicates the amount of spherical aberration for the d-line (wavelength 587.56 nm), f-line (wavelength 486.13 nm), C-line (wavelength 656.27 nm), and g-line (wavelength 435.83 nm). It shows. The scale on the horizontal axis is the defocus amount, which is −0.4 to +0.4 [mm]. In the astigmatism diagram, S indicates the amount of astigmatism on the sagittal image plane, and M indicates the amount of astigmatism on the meridional image surface. The horizontal axis is the same as spherical aberration. The distortion aberration diagram shows the amount of distortion for the d-line. For distortion aberration, the scale on the horizontal axis is -15 to +15 [%]. The chromatic aberration diagram shows the amount of chromatic aberration at the f-line, C-line, and g-line. ω is the imaging half angle of view (°), which is the angle of view based on paraxial calculation.

Next, the characteristic configuration of the zoom lens B0 of each example will be described.

The zoom lens B0 of each example includes a first lens group B1 with negative refractive power and a plurality of lens groups arranged in order from the object side to the image side, and has a rear group BR with positive refractive power as a whole. . In the zoom lens B0 of each embodiment, the distance between adjacent lens groups changes during zooming from the wide-angle end to the telephoto end. The rear group BR includes a positive refractive power lens group Fp, at least two positive refractive power lens groups, and a negative refractive power lens group Fn, which are arranged in order from the object side to the image side. Lens group Fp and lens group Fn move in the optical axis direction during focusing from infinity to close range.

By arranging multiple lens groups with positive refractive power in the rear group BR, it is possible to suppress the overall lens length even when increasing the aperture, and by dividing the lens into multiple parts and moving them, it is possible to eliminate spherical aberration over the entire zoom range. Fluctuations in field curvature can be suppressed.

In addition to the lens group Fp, which is the main focus group, by moving the lens group Fn, which has a high off-axis ray height, fluctuations in field curvature during zooming and at close distances are suppressed, and it is good even at bright F-numbers. It is possible to obtain excellent imaging performance.

Furthermore, the zoom lens B0 of each example satisfies the following conditional expression (1).

1.0<ENPw/fw<3.0...(1)
Here, ENPw is the entrance pupil position of the zoom lens B0 at the wide-angle end. fw is the focal length of the zoom lens B0 at the wide-angle end.

Conditional expression (1) defines an appropriate range of the entrance pupil position ENPw with respect to the focal length fw at the wide-angle end, and indicates an appropriate range of the exit pupil position ENPw of the zoom lens B0. If the upper limit of conditional expression (1) is exceeded, an excessive number of lenses are placed on the object side of the entrance pupil, and the lens diameter becomes too large and the total lens length becomes too long. If the lower limit of conditional expression (1) is not reached, the number of lenses on the object side of the entrance pupil will decrease, distortion will become too large, and it will be difficult to correct field curvature and coma flare.

Moreover, it is more preferable that the numerical range of conditional formula (1) is within the range of the following conditional formula (1a).

1.2<ENPw/fw<2.5...(1a)
Further, it is more preferable that the numerical range of conditional expression (1) is the range of conditional expression (1b) below.

1.5<ENPw/fw<2.0...(1b)
Next, a configuration that is preferably satisfied in the zoom lens B0 of each example will be described.

The zoom lens B0 includes a first lens group B1 with negative refractive power, a second lens group B2 with positive refractive power, a third lens group B3 with positive refractive power, and a positive refractive power, which are arranged in order from the object side to the image side. It consists of a fourth lens group B4 having a refractive power of , a fifth lens group B5 having a negative refractive power, and a sixth lens group B6 having a positive refractive power. The second lens group B2 to the sixth lens group B6 correspond to the rear group BR, and the rear group BR as a whole has positive refractive power.

During zooming from the wide-angle end to the telephoto end, the first lens group B1 moves, and the second lens group B2, the third lens group B3, the fourth lens group B4, the fifth lens group B, and the sixth lens group B6 move. moves toward the object.

During zooming from the wide-angle end to the telephoto end, the first lens group B1 moves toward the image side at the intermediate position and toward the object side at the telephoto position, in a so-called convex trajectory toward the image side. This shortens the overall lens length at the wide-angle end. Here, the convex locus of lens group A toward the image side refers to the amount of movement of lens group A from the wide-angle end when focusing on infinity, with the case where it moves toward the image side as a positive value, and the amount of movement during zooming. This means that the amount of movement takes the maximum value in the intermediate region. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group B1 and the second lens group B2 narrows, and the distance between the second lens group B2 and third lens group B3 narrows. Furthermore, when zooming from the wide-angle end to the telephoto end, the distance between the third lens group B3 and the fourth lens group B4 narrows, the distance between the fourth lens group B4 and the fifth lens group B5B5 widens, and the distance between the third lens group B3 and the fourth lens group B5 widens. The interval between the sixth lens group B6 increases.

In each example, the lens group Fp corresponds to the second lens group B2, and the lens group Fn corresponds to the fifth lens group B5. During focusing from infinity to close range, the lens group Fp, which is the main focus group, moves toward the image side, and the lens group Fn moves toward the object side so as to cancel out the spherical aberration and field curvature generated in the lens group Fp.

By moving the lens group Fp and the lens group Fn not only during focusing but also during zooming, it reduces fluctuations in various aberrations such as curvature of field due to zooming, and contributes to downsizing of the zoom lens B0. ing.

Since the lens group Fp and the lens group Fn are required to move quickly during zooming, it is preferable that the lens group Fp and the lens group Fn be light in weight. In each embodiment, the weight of the moving lens group is reduced by making the lens group Fp a cemented lens of a negative lens and a positive lens, and making the lens group Fn a negative lens.

Zooming is mainly performed by the first lens group B1 having negative refractive power and the second to fourth lens groups B2 to B4 having positive refractive power. By making the second to fourth lens groups B2 to B4 each have a positive refractive power, the refractive power of each of these lens groups can be weakened, and even if the apertures of these lens groups are increased, the occurrence of various aberrations can be suppressed. .

When zooming from the wide-angle end to the telephoto end, the fifth lens group B5 with negative refractive power moves to widen the distance between it and the fourth lens group B4, thereby improving the image quality during zooming from the wide-angle end to the telephoto end. This assists in point changes and reduces zoom fluctuations in field curvature.

By using the sixth lens group B6 as a lens group with positive refractive power, it is possible to suppress the angle of incidence of light rays on the image plane IP, and it is possible to reduce uneven brightness and color unevenness that occur over the entire screen. Furthermore, by moving the sixth lens group B6 toward the object side during zooming from the wide-angle end to the telephoto end, changes in the image plane incidence angle are suppressed and the lens diameter is prevented from becoming unnecessarily large.

With a large-diameter wide-angle zoom lens, it is difficult to properly perform vignetting of peripheral light, and a variable auxiliary diaphragm is often provided in addition to the aperture diaphragm SP. In each embodiment, the aperture diaphragm SP is arranged between the third lens group B3 and the fourth lens group B4, and the distance between the second lens group B2 and the aperture diaphragm SP is changed with zooming, thereby creating a variable auxiliary diaphragm. You can set vignetting appropriately even without it.

The first lens group B1 includes three or four negative lenses and one positive lens. Preferably, the first lens group B1 includes three negative lenses and a cemented lens of a negative lens and a positive lens, arranged in order from the object side to the image side. Further, the first lens group B1 includes a negative meniscus lens L11 which is disposed closest to the object side and has a convex shape on the object side, and a negative meniscus lens L11 which has a convex shape on the object side and which is disposed adjacent to the image side of the negative meniscus lens L11. It includes a meniscus lens L12.

In a wide-angle lens whose half angle of view exceeds 50 degrees, the angle of incidence of light from the object side is extremely large. For this reason, coma flare, field curvature, and distortion occurring on each lens surface tend to increase, and it is necessary to refract light rays smoothly with respect to the lens surface, so it is preferable to adopt the above configuration.

Next, preferred conditions that the zoom lens B0 of each example satisfies will be described. It is preferable that the zoom lens B0 of each example satisfies one or more of the following conditional expressions (2) to (9).

0.05<DP/Lw<0.40...(2)
2.0<POw/BFw<7.0...(3)
3.0<fFp/fw<8.0...(4)
-10<fFn/fw<-1...(5)
4.0<fBa/fw<100.0...(6)
1.0<D1/fw<5.0 (7)
0.86<N11/N12<1.00 (8)
0.2<BFw/fw<3.0...(9)
Here, Dp is the thickness on the optical axis of the lens group Bp (fourth lens group B4) having a positive refractive power and arranged adjacent to the object side of the lens group Fn. Lw is the distance on the optical axis from the lens surface closest to the object side of the zoom lens B0 to the image plane IP at the wide-angle end. POw is the distance on the optical axis from the exit pupil position of the zoom lens B0 to the image plane IP at the wide-angle end. BFw is the back focus of the zoom lens B0 at the wide-angle end. fFp is the focal length of the lens group Fp. fFn is the focal length of lens group Fn. fBa is the focal length of a lens group Ba (third lens group B3) having a positive refractive power and arranged adjacent to the image side of the lens group Fp. D1 is the thickness of the first lens group B1 on the optical axis. N11 is the refractive index of the negative meniscus lens L11. N12 is the refractive index of the negative meniscus lens L12.

Conditional expression (2) defines the ratio between the thickness Dp of the lens group Bp arranged adjacent to the object side of the lens group Fn and the total lens length Lw, and determines an appropriate value for the thickness Dp of the lens group Bp. It shows the range. The refractive power of the lens group Bp tends to increase as the aperture increases. Further, in order to satisfactorily correct spherical aberration and axial chromatic aberration, it is preferable that the lens group Bp has a sufficient thickness and that two or more positive lenses and two or more negative lenses are arranged. If the upper limit of conditional expression (2) is exceeded, the lens group Bp becomes too thick, making it impossible to provide a sufficient air gap necessary for zooming, which is not preferable. If the lower limit of conditional expression (2) is not reached, the lens group Bp becomes too thin, the refractive power of the lens elements included in the lens group Bp decreases too much, and aberration correction due to an increase in the aperture becomes insufficient, which is preferable. do not have.

Conditional expression (3) defines the relationship between the exit pupil position POw and the back focus BFw, and indicates an appropriate range of the image plane incidence angle. Exceeding the upper limit of conditional expression (3) is not preferable because the exit pupil at the wide-angle end becomes too long and the overall length of the lens becomes long. If the lower limit of conditional expression (3) is not reached, the exit pupil will become too short and the incident angle of the image plane IP will become too strong, resulting in excessive brightness unevenness and color unevenness, which is not preferable.

Conditional expression (4) defines the ratio of the focal length fFp of the lens group Fp to the focal length fw of the zoom lens B0 at the wide-angle end, and indicates the appropriate range of the refractive power of the lens group Fp. . If the upper limit of conditional expression (4) is exceeded, the amount of lens movement during focusing becomes too large and the total length of the lens becomes long, which is not preferable. If the lower limit of conditional expression (4) is not reached, the refractive power of the lens group Fp becomes too strong, making it impossible to satisfactorily correct fluctuations in spherical aberration during zooming or focusing, which is not preferable.

Conditional expression (5) defines the ratio of the focal length fFn of the lens group Fn to the focal length fw of the zoom lens B0 at the wide-angle end, and indicates the appropriate range of the refractive power of the lens group Fn. . Exceeding the upper limit of conditional expression (5) is not preferable because the refractive power of the lens group Fn becomes too strong and changes in spherical aberration and field curvature when the lens group Fn moves in the optical axis direction become large. If the lower limit of conditional expression (5) is not reached, the amount of movement of the lens group Fn during zooming and focusing becomes too large, which is not preferable because the overall length of the lens becomes long.

Conditional expression (6) defines the ratio of the focal length fBa of the lens group Ba to the focal length fw of the zoom lens at the wide-angle end, and indicates an appropriate range of the refractive power of the lens group Ba. If the upper limit of conditional expression (6) is exceeded, the refractive power of the lens group Ba becomes too weak, it is necessary to strengthen the refractive power of the lens group Fp, and comatic aberration and spherical aberration worsen, which is not preferable. If the lower limit of conditional expression (6) is not reached, the refractive power of the lens group Ba becomes too strong, it is necessary to weaken the refractive power of the lens group Fp, and the amount of movement of the lens group Fp during focusing becomes large, which is preferable. do not have.

Conditional expression (7) defines the ratio between the thickness D1 of the first lens group B1 and the focal length fw of the zoom lens at the wide-angle end, and determines the appropriate range of the thickness D1 of the first lens group B1. It shows. If the upper limit of conditional expression (7) is exceeded, the performance at the wide-angle end will improve, but the overall lens length and lens diameter will increase, which is not preferable. If the lower limit of conditional expression (7) is not reached, sufficient lenses cannot be arranged for the angle of view, and field curvature and distortion cannot be corrected satisfactorily, which is not preferable.

Conditional expression (8) defines the ratio of the refractive index N11 of the negative meniscus lens L11 of the first lens group B0 to the refractive index N12 of the negative meniscus lens L12, and the ratio of the refractive index of the lens of the first lens group B1. Preferred ranges are shown. When the upper limit of conditional expression (8) is exceeded, the refractive index N11 of the negative meniscus lens L11 becomes higher than the refractive index N12 of the negative meniscus lens L12, and chromatic aberration occurs in the negative meniscus lens L11, which has a relatively high ray height. is undesirable because it increases If the lower limit of conditional expression (8) is exceeded, the refractive index N11 of the negative meniscus lens L11 becomes too low than the refractive index N12 of the negative meniscus lens L12, and the uneven thickness ratio of the negative meniscus lens L11 becomes large in a region where the angle of view is large. This is not preferable because it increases the lens diameter and requires increasing the lens diameter.

Conditional expression (9) defines the ratio of the back focus BFw to the focal length fw of the zoom lens at the wide-angle end, and indicates a preferable range of the back focus BFw with respect to the focal length fw. If the upper limit of conditional expression (9) is exceeded, the back focus BFw will be too long relative to the focal length fw, making it difficult to shorten the overall lens length, which is not preferable. If the lower limit of conditional expression (9) is not reached, the back focus BFw is too short and the lens and barrel are likely to interfere with the sensor, which is not preferable.

Note that the numerical ranges of conditional expressions (2) to (9) are more preferably within the ranges of conditional expressions (2a) to (9a) below.

0.10<DP/Lw<0.30...(2a)
3.0<POw/BFw<6.0...(3a)
3.5<fFp/fw<7.0...(4a)
-8.0<fFn/fw<-1.5...(5a)
5.0<fBa/fw<50.0...(6a)
1.5<D1/fw<4.5...(7a)
0.90<N11/N12<1.00...(8a)
0.5<BFw/fw<2.0...(9a)
Furthermore, it is more preferable that the numerical ranges of conditional expressions (2) to (9) be within the range of conditional expressions (2b) to (9b) below.

0.15<DP/Lw<0.25...(2b)
3.6<POw/BFw<5.0...(3b)
4.0<fFp/fw<6.0...(4b)
-6.0<fFn/fw<-1.8...(5b)
7.0<fBa/fw<30.0...(6b)
2.0<D1/fw<4.0...(7b)
0.92<N11/N12<1.00...(8b)
0.8<BFw/fw<1.5...(9b)
Next, the zoom lens B0 of each example will be described in detail.

The zoom lens B0 of Example 1 has a wide angle of view with a half angle of view of 60.4 degrees at the wide-angle end, and achieves brightness with an F value of about 2.8. As shown in FIG. 2, fluctuations in spherical aberration and field curvature are suppressed from the wide-angle end to the telephoto end, ensuring imaging performance that can support a bright F-number. By leaving the amount of distortion that can be corrected through image processing and reducing the correction burden on the first lens group B1, the lens diameter and overall length of the first lens group B1 have been reduced. . As shown in FIG. 3, good imaging performance with suppressed fluctuations in spherical aberration and field curvature is ensured from infinity to close range.

The zoom lens B0 of Example 2 has a half angle of view of 62.4 degrees at the wide-angle end, making it even wider than Example 1, while achieving brightness with an F value of about 2.8 to 4.0. ing. Although the lens diameter of the first lens group B1 increases by further widening the angle of view compared to Example 1, the overall length of the lens can be shortened by suppressing the F value at the telephoto end. As shown in FIGS. 5 and 6, the zoom lens B0 of Example 2 ensures good imaging performance with suppressed fluctuations in spherical aberration and field curvature from infinity to close range.

In the zoom lens B0 of Example 3, the half angle of view at the wide-angle end is 56.5 degrees, and the F value is brightened to about 2.0. By increasing the F value, the lens diameter of the rear group BR increases, but by suppressing the variable power ratio, the increase in the total lens length can be suppressed. Furthermore, even when the rear group BR has a large aperture, the floating lens group Fn can be placed on the image side where off-axis rays are easily separated, so that aberration fluctuations during focusing can be favorably corrected. As shown in FIGS. 8 and 9, the zoom lens B0 of Example 3 ensures good imaging performance with suppressed fluctuations in spherical aberration and field curvature from infinity to close range.

Numerical Examples 1 to 3 corresponding to Examples 1 to 3, respectively, are shown below.

In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the axial distance (distance on the optical axis) between the m-th surface and the (m+1)-th surface. . However, m is the number of the surface counted from the light incident side. Further, nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. The Abbe number νd of a certain material is νd when the refractive index at the Fraunhofer line d line (587.6 nm), F line (486.1 nm), and C line (656.3 nm) is Nd, NF, and NC. It is expressed as =(Nd-1)/(NF-NC). The effective diameter means the maximum diameter of a region (effective region) through which an effective light beam contributing to image formation passes through the lens surface.

In each numerical example, d, focal length (mm), F number, and half angle of view (°) are all values when the zoom lens B0 of each example focuses on an object at infinity. The image height represents a paraxial image height, and it is assumed that image distortion due to distortion aberration is corrected by processing the photographed image. "Back focus BF" is the distance on the optical axis from the final lens surface (the lens surface closest to the image side) to the paraxial image surface expressed in air equivalent length. The "total lens length" is the distance on the optical axis from the frontmost surface (lens surface closest to the object side) to the final surface of the zoom lens plus the back focus. A "lens group" is not limited to a case where it is composed of a plurality of lenses, but also includes a case where it is composed of a single lens.

Furthermore, if the optical surface is an aspherical surface, an * symbol is attached to the right side of the surface number. The aspherical shape is expressed as follows: When A8, A10, and A12 are the aspherical coefficients of each order,
x=(h ² /R)/[1+{1-(1+k)(h/R) ² } ^1/2 ]+A4×h ⁴ +A6×h ⁶
+A8×h ⁸ +A10×h ¹⁰ +A12×h ¹²
It is expressed as Note that "e±XX" in each aspheric coefficient means "×10± ^XX ".

In the interval data, OBJ indicates object distance, which is the distance from the object position to the image plane IP.

(Numerical Example 1)
Unit: mm
Surface data Surface number rd nd νd Effective diameter
1* 36.479 3.20 1.76450 49.1 60.00
2* 13.916 12.50 41.93
3* 89.903 2.20 1.85400 40.4 40.45
4* 38.368 6.65 32.36
5 -288.607 1.40 1.43875 94.7 32.06
6 64.991 3.40 30.67
7 -107.543 1.40 1.49700 81.5 30.51
8 28.486 5.50 1.85478 24.8 29.70
9 160.242 (variable) 29.06
10 ∞ 0.50 21.23
11 37.933 0.90 2.00069 25.5 20.36
12 17.522 5.00 1.85025 30.1 19.93
13 308.918 (variable) 20.05
14 26.920 1.00 2.00069 25.5 21.16
15 16.869 5.40 1.51633 64.1 20.42
16 525.314 1.60 20.50
17 (Aperture) ∞ (Variable) 14.00
18* 40.200 4.75 1.49700 81.5 20.81
19 -39.643 5.30 20.51
20 -22.867 0.90 1.85478 24.8 18.00
21 31.429 5.60 1.92286 20.9 18.63
22 -24.532 0.30 19.00
23 -75.737 4.85 1.49700 81.5 19.29
24 -15.814 0.90 1.77047 29.7 19.72
25 72.597 0.30 21.86
26 32.068 6.85 1.59522 67.7 23.88
27 -34.523 (variable) 24.49
28* -36.337 1.20 1.88202 37.2 24.42
29* -163.280 (variable) 25.48
30 205.193 4.30 1.85478 24.8 37.42
31 -122.444 (variable) 38.00
Image plane ∞

Aspheric data 1st surface
K = 0.00000e+000 A4 =-9.81021e-006 A6=-5.15449e-010 A8= 1.45629e-011
A10=-1.68208e-014 A12= 6.83429e-018
2nd side
K =-6.76330e-001 A4 =-8.71079e-006 A6=-4.53718e-008 A8=-8.35053e-011
A10= 1.16441e-013
3rd page
K = 0.00000e+000 A4 =-9.67785e-006 A6= 4.16533e-008 A8=-7.09715e-011
A10=5.02745e-014 A12=-4.24754e-018
Side 4
K = 1.71066e+000 A4 =-1.68380e-006 A6= 8.29296e-008 A8= 8.97570e-012
A10= 2.71284e-013
Side 18
K = 0.00000e+000 A4 = 5.15619e-006 A6= 1.92497e-008 A8= 3.30914e-011
A10=3.74306e-013 A12=-1.31534e-015
Page 28
K = 0.00000e+000 A4 = 1.46758e-006 A6= 2.52186e-008 A8= 3.15661e-011
A10=-7.76255e-013
Page 29
K = 0.00000e+000 A4 = 2.32242e-005 A6= 4.28486e-008 A8= 5.23957e-011
A10=-5.71571e-013

Various data Zoom ratio 1.94
Wide Angle Intermediate Telephoto Focal Length 12.29 18.00 23.80
F number 2.93 2.93 2.93
Half angle of view (°) 60.39 50.25 42.27
Image height 21.64 21.64 21.64
Lens total length 138.05 132.29 134.83
BF 13.86 17.55 19.48
Entrance pupil position 21.05 20.14 19.65
Exit pupil position -52.94 -62.81 -82.15
Front principal point position 31.08 34.11 37.88
Back principal point position 1.57 -0.44 -4.32

interval data
Wide-angle Intermediate Telephoto Wide-angle Intermediate Telephoto
OBJ Mugen Mugen Mugen 280mm 280mm 280mm
d 9 21.16 7.44 1.00 22.97 9.83 3.70
d13 4.81 3.89 4.19 3.00 1.50 1.49
d17 6.73 3.87 1.00 6.73 3.87 1.00
d27 2.61 4.50 5.89 2.55 3.97 5.15
d29 2.98 9.14 17.36 3.04 9.66 18.11
d31 13.86 17.55 19.48 13.86 17.55 19.48

Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 -16.84 36.25 7.89 -20.10
2 10 65.32 6.40 -0.32 -3.93
3 14 124.06 8.00 -2.28 -7.88
4 18 37.78 29.75 13.69 -11.14
5 28 -53.23 1.20 -0.18 -0.82
6 30 90.26 4.30 1.46 -0.87

Single lens data lens Starting surface Focal length
1 1 -31.35
2 3 -79.95
3 5 -120.76
4 7 -45.16
5 8 39.77
6 11 -33.27
7 12 21.68
8 14 -47.52
9 15 33.63
10 18 40.97
11 20 -15.37
12 21 15.68
13 23 39.16
14 24 -16.78
15 26 29.05
16 28 -53.23
17 30 90.26

(Numerical Example 2)
Unit: mm
Surface data Surface number rd nd νd Effective diameter
1* 41.595 3.20 1.76450 49.1 66.00
2* 14.582 14.40 45.21
3* 75.791 2.20 1.85400 40.4 43.58
4* 38.270 6.60 34.73
5 -1287.449 1.40 1.43875 94.7 34.35
6 43.598 4.00 32.06
7 -283.917 1.40 1.49700 81.5 31.87
8 29.039 5.50 1.85478 24.8 30.61
9 125.684 (variable) 29.82
10 ∞ 0.50 19.19
11 35.240 0.90 2.00069 25.5 17.92
12 15.326 4.30 1.85025 30.1 16.90
13 591.666 (variable) 16.26
14 22.913 1.00 2.00069 25.5 15.23
15 14.799 3.20 1.51823 58.9 14.62
16 64.989 1.95 14.53
17 (aperture) ∞ (variable) 14.64
18* 34.986 5.00 1.49700 81.5 15.03
19 -34.275 4.57 15.19
20 -20.081 0.90 1.85478 24.8 15.28
21 25.189 5.60 1.92286 20.9 17.12
22 -20.719 0.30 18.03
23 -49.623 4.85 1.49700 81.5 18.02
24 -13.283 0.80 1.77047 29.7 18.31
25 94.209 0.30 20.44
26 33.166 6.65 1.59522 67.7 22.32
27 -28.703 (variable) 23.02
28* -26.977 1.20 1.95150 29.8 22.97
29* -106.927 (variable) 24.48
30 155.839 5.00 1.80518 25.4 37.37
31 -95.700 (variable) 38.00
Image plane ∞

Aspheric data 1st surface
K = 0.00000e+000 A4 =-3.71522e-006 A6=-8.33123e-009 A8= 1.87934e-011
A10=-1.53912e-014 A12= 5.11160e-018
2nd side
K =-6.67750e-001 A4 =-5.39613e-006 A6=-2.82370e-008 A8=-8.66836e-011
A10=8.55987e-014
3rd page
K = 0.00000e+000 A4 =-1.96419e-005 A6= 6.00839e-008 A8=-8.77427e-011
A10=7.00538e-014 A12=-2.17642e-017
Side 4
K = 2.41969e+000 A4 =-1.41786e-005 A6= 6.80301e-008 A8= 2.54708e-011
A10=3.78623e-014
Side 18
K = 0.00000e+000 A4 = 1.01004e-005 A6=-3.16875e-008 A8= 1.95288e-009
A10=-2.50933e-011 A12= 1.22740e-013
Page 28
K = 0.00000e+000 A4 =-5.04728e-006 A6= 2.33745e-008 A8= 4.23117e-010
A10=-1.98750e-012
Page 29
K = 0.00000e+000 A4 = 1.66938e-005 A6= 5.24775e-008 A8= 1.42848e-010
A10=-9.03803e-013

Various data Zoom ratio 2.11
Wide Angle Intermediate Telephoto Focal Length 11.30 18.00 23.80
F number 2.93 3.49 4.09
Half angle of view (°) 62.42 50.24 42.27
Image height 21.64 21.64 21.64
Lens total length 138.04 131.89 136.22
BF 13.87 19.38 22.14
Entrance pupil position 21.34 20.27 19.86
Exit pupil position -45.34 -59.80 -84.48
Front principal point position 30.49 34.18 38.35
Back principal point position 2.57 1.38 -1.66

interval data
Wide-angle Intermediate Telephoto Wide-angle Intermediate Telephoto
OBJ Mugen Mugen Mugen 280mm 280mm 280mm
d 9 24.50 7.48 1.00 26.46 9.52 3.43
d13 4.50 3.61 4.57 2.54 1.57 2.14
d17 4.85 3.13 1.00 4.85 3.13 1.00
d27 2.05 3.82 5.17 1.93 3.57 4.66
d29 2.56 8.76 16.62 2.68 9.01 17.13
d31 13.87 19.38 22.14 13.87 19.38 22.14


Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 -16.63 38.70 8.22 -21.42
2 10 57.64 5.70 0.01 -3.24
3 14 239.11 6.15 -8.93 -13.11
4 18 33.05 28.97 13.86 -10.53
5 28 -38.20 1.20 -0.21 -0.83
6 30 74.29 5.00 1.73 -1.06

Single lens data lens Starting surface Focal length
1 1 -30.96
2 3 -93.03
3 5 -96.08
4 7 -52.93
5 8 43.05
6 11 -27.73
7 12 18.44
8 14 -44.51
9 15 36.19
10 18 35.69
11 20 -12.95
12 21 13.08
13 23 34.95
14 24 -15.06
15 26 26.93
16 28 -38.20
17 30 74.29

(Numerical Example 3)
Unit: mm
Surface data Surface number rd nd νd Effective diameter
1* 48.910 3.20 1.76450 49.1 59.81
2* 16.800 9.72 44.21
3* 50.911 2.40 1.85135 40.1 42.97
4* 31.703 6.25 35.22
5 164.177 1.60 1.43875 94.7 34.97
6 59.636 7.10 33.66
7 -67.597 1.40 1.49700 81.5 32.70
8 32.748 5.00 1.85478 24.8 32.21
9 143.304 (variable) 31.78
10 ∞ 0.50 27.73
11 65.439 0.90 2.00069 25.5 26.88
12 25.045 6.20 1.85025 30.1 26.08
13 -258.882 (variable) 25.99
14 48.697 2.70 1.77250 49.6 27.16
15 72.406 0.30 26.96
16 35.241 1.20 2.00069 25.5 27.18
17 21.000 5.82 1.51823 58.9 26.11
18 81.369 7.30 26.15
19 (aperture) ∞ (variable) 27.38
20* 34.641 8.50 1.49700 81.5 28.19
21 -36.153 2.72 27.70
22 -31.063 1.00 1.85478 24.8 25.52
23 32.955 6.50 1.92286 20.9 25.88
24 -47.640 0.30 26.09
25 94.207 4.40 1.49700 81.5 25.35
26 -38.129 0.80 1.77047 29.7 25.22
27 72.205 0.30 25.57
28 25.407 7.05 1.59522 67.7 27.30
29 -110.853 (variable) 26.94
30* -596.105 1.20 1.88202 37.2 25.51
31* 37.639 (variable) 25.36
32 118.188 3.30 1.96300 24.1 32.28
33 -1000.000 (variable) 32.80
Image plane ∞

Aspheric data 1st surface
K = 0.00000e+000 A4 =-4.08812e-006 A6=-3.84183e-009 A8= 1.44799e-011
A10=-1.36535e-014 A12= 4.76412e-018
2nd side
K =-6.95711e-001 A4 =-2.38693e-006 A6=-2.68831e-008 A8=-5.85358e-011
A10=8.31504e-014
3rd page
K = 0.00000e+000 A4 =-1.76742e-005 A6= 4.47027e-008 A8=-6.04816e-011
A10= 2.59679e-014 A12= 1.00276e-017
Side 4
K =-8.92251e-001 A4 =-8.91359e-006 A6= 8.42729e-008 A8=-4.38131e-011
A10= 1.82471e-013
Page 20
K = 0.00000e+000 A4 = 1.91378e-006 A6= 1.53503e-009 A8= 1.46978e-011
A10=-6.42805e-014 A12= 8.13491e-017
Page 30
K = 0.00000e+000 A4 =-1.60809e-005 A6=-3.25453e-009 A8=-3.85420e-011
A10=-3.37311e-014
Page 31
K = 0.00000e+000 A4 = 1.19619e-005 A6= 1.64220e-008 A8= 8.08864e-011
A10=-5.75092e-013

Various data Zoom ratio 1.50
Wide Angle Intermediate Telephoto Focal Length 14.30 18.00 21.50
F number 2.06 2.06 2.06
Half angle of view (°) 56.54 50.24 45.18
Image height 21.64 21.64 21.64
Lens total length 148.04 141.94 139.46
BF 13.87 16.78 20.30
Entrance pupil position 22.85 22.32 22.05
Exit pupil position -44.62 -45.23 -43.55
Front principal point position 33.66 35.10 36.31
Back principal point position -0.43 -1.22 -1.20

interval data
Wide-angle Intermediate Telephoto Wide-angle Intermediate Telephoto
OBJ Mugen Mugen Mugen 280mm 280mm 280mm
d 9 14.55 6.09 0.95 17.16 9.08 4.17
d13 5.76 4.49 4.72 3.15 1.50 1.50
d19 7.30 4.36 1.00 7.30 4.36 1.00
d29 3.18 3.89 4.43 3.09 3.65 4.12
d31 5.71 8.66 10.41 5.80 8.90 10.72
d33 13.87 16.78 20.30 13.87 16.78 20.30

Zoom lens group data group Starting surface Focal length Lens length Front principal point position Rear principal point position
1 1 -18.56 36.67 8.09 -20.02
2 10 80.09 7.60 1.29 -3.05
3 14 185.69 17.32 -11.11 -23.74
4 20 30.39 31.57 11.70 -12.21
5 30 -40.10 1.20 0.60 -0.04
6 32 109.92 3.30 0.18 -1.51

Single lens data lens Starting surface Focal length
1 1 -34.98
2 3 -104.72
3 5 -214.46
4 7 -44.18
5 8 48.65
6 11 -41.00
7 12 27.13
8 14 183.41
9 16 -54.22
10 17 52.88
11 20 37.07
12 22 -18.57
13 23 21.96
14 25 55.22
15 26 -32.28
16 28 35.41
17 30 -40.10
18 32 109.92

Various values in each numerical example are summarized in Table 1 below.

[Imaging device]
Next, an example of a digital camera (imaging device) using the zoom lens B0 of the present invention as an imaging optical system will be described with reference to FIG. FIG. 10 is a schematic diagram of the imaging device (digital still camera) 10 of this embodiment. The imaging device 10 includes a camera body 13, a zoom lens 11 similar to any of the first to third embodiments described above, and a light receiving element (imaging element) 12 that photoelectrically converts an optical image formed by the zoom lens 11. .

The imaging device 10 of this embodiment has an ultra-wide-angle zoom lens 11 that is small and provides high optical performance over the entire range of object distances, making it possible to obtain high-quality images.

Note that as the light receiving element 12, an imaging element such as a CCD or a CMOS sensor can be used. At this time, by electrically correcting various aberrations such as distortion aberration and chromatic aberration of the image acquired by the light receiving element 12, it is also possible to improve the quality of the output image. The camera body 13 may be a so-called single-lens reflex camera with a quick turn mirror, or a so-called mirrorless camera without a quick turn mirror.

The zoom lens B0 of each embodiment described above is not limited to the digital still camera shown in FIG. 10, but can be applied to various optical devices such as a silver halide film camera, a video camera, and a telescope.
[Imaging system]
Note that an imaging system (surveillance camera system) including the zoom lens B0 of each embodiment and a control unit that controls the zoom lens B0 may be configured. In this case, the control unit can control the zoom lens B0 so that each lens group moves as described above during zooming, focusing, and image blur correction. At this time, the control section does not need to be configured integrally with the zoom lens B0, and the control section may be configured separately from the zoom lens B0. For example, a configuration may be adopted in which a control unit (control device) located far from a drive unit that drives each lens of the zoom lens B0 includes a transmitting unit that sends a control signal (command) for controlling the zoom lens B0. May be adopted. According to such a control unit, the zoom lens B0 can be remotely controlled.

Furthermore, a configuration may be adopted in which the control section is provided with an operation section such as a controller or a button for remotely controlling the zoom lens B0, so that the zoom lens B0 is controlled in accordance with user's input to the operation section. For example, an enlargement button and a reduction button are provided as the operation section. Then, a signal is sent from the control unit to the drive unit of zoom lens B0 so that when the user presses the enlarge button, the magnification of zoom lens B0 increases, and when the user presses the reduce button, the magnification of zoom lens B0 decreases. You can configure it like this.

Further, the imaging system may include a display unit such as a liquid crystal panel that displays information regarding zooming (movement state) of the zoom lens B0. The information regarding the zoom of the zoom lens B0 is, for example, the zoom magnification (zoom state) and the amount of movement (movement state) of each lens group. In this case, the user can remotely operate the zoom lens B0 via the operation unit while viewing information regarding the zoom of the zoom lens B0 shown on the display unit. At this time, the display section and the operation section may be integrated, for example, by employing a touch panel or the like.

The disclosure of each of the above embodiments includes the following configurations.

(Configuration 1)
It includes a first lens group with negative refractive power and a plurality of lens groups arranged in order from the object side to the image side, and has a rear group with positive refractive power as a whole, and when zooming from the wide-angle end to the telephoto end. A zoom lens in which the distance between adjacent lens groups changes,
The rear group includes a positive refractive power lens group Fp, at least two positive refractive power lens groups, and a negative refractive power lens group Fn arranged in order from the object side to the image side,
The lens group Fp and the lens group Fn move during focusing from infinity to a close distance,
When the entrance pupil position of the zoom lens at the wide-angle end is ENPw, and the focal length of the zoom lens at the wide-angle end is fw,
1.0<ENPw/fw<3.0
A zoom lens characterized by satisfying the following conditional expression.
(Configuration 2)
When focusing from infinity to close range, the lens group Fp moves toward the image side,
The zoom lens according to configuration 1, wherein during zooming from a wide-angle end to a telephoto end, an interval between the lens group Fp and a lens group disposed adjacent to the image side of the lens group Fp narrows.
(Configuration 3)
When focusing from infinity to close range, the lens group Fn moves toward the object side,
The zoom lens according to configuration 1 or 2, wherein during zooming from the wide-angle end to the telephoto end, the distance between the lens group Fn and a lens group arranged adjacent to the image side of the lens group Fn increases. .
(Configuration 4)
The thickness on the optical axis of the lens group with positive refractive power arranged adjacent to the object side of the lens group Fn is Dp, and the light from the lens surface closest to the object side of the zoom lens at the wide-angle end to the image plane When the distance on the axis is Lw,
0.05<Dp/Lw<0.40
4. The zoom lens according to any one of configurations 1 to 3, which satisfies the following conditional expression.
(Configuration 5)
When the distance on the optical axis from the exit pupil position of the zoom lens to the image plane at the wide-angle end is POw, and the air-equivalent length of the back focus of the zoom lens at the wide-angle end is BFw,
2.0<Pow/BFw<6.0
5. The zoom lens according to any one of configurations 1 to 4, which satisfies the following conditional expression.
(Configuration 6)
When the focal length of the lens group Fp is fFp,
3.0<fFp/fw<8.0
6. The zoom lens according to any one of configurations 1 to 5, which satisfies the following conditional expression.
(Configuration 7)
When the focal length of the lens group Fn is fFn,
-10<fFn/fw<-1
7. The zoom lens according to any one of configurations 1 to 6, which satisfies the following conditional expression.
(Configuration 8)
When the focal length of a lens group with positive refractive power arranged adjacent to the image side of the lens group Fp is fBa,
4.0<fBa/fw<100.0
8. The zoom lens according to any one of configurations 1 to 7, which satisfies the following conditional expression.
(Configuration 9)
When the thickness of the first lens group on the optical axis is D1,
1.0<D1/fw<5.0
9. The zoom lens according to any one of configurations 1 to 8, which satisfies the following conditional expression.
(Configuration 10)
10. The zoom lens according to any one of configurations 1 to 9, wherein the first lens group includes three or four negative lenses and one positive lens.
(Configuration 11)
The first lens group includes a negative meniscus lens L11 disposed closest to the object side of the first lens group and having a convex shape on the object side, and a negative meniscus lens L11 disposed adjacent to the image side of the negative meniscus lens L11 on the object side. 11. The zoom lens according to any one of configurations 1 to 10, including a convex negative meniscus lens L12.
(Configuration 12)
When the refractive index of the negative meniscus lens L11 is N11, and the refractive index of the negative meniscus lens L12 is N12,
0.86<N11/N12<1.00
The zoom lens according to configuration 11, wherein the zoom lens satisfies the following conditional expression.
(Configuration 13)
The rear group includes a lens group with a positive refractive power disposed closest to the image side,
When the back focus of the zoom lens at the wide-angle end is BFw,
0.2<BFw/fw<3.0
13. The zoom lens according to any one of configurations 1 to 12, which satisfies the following conditional expression.
(Configuration 14)
The rear group includes a second lens group with positive refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a negative refractive power, which are arranged in order from the object side to the image side. 14. The zoom lens according to any one of structures 1 to 13, characterized in that the zoom lens comprises a fifth lens group having a positive refractive power and a sixth lens group having a positive refractive power.
(Configuration 15)
During zooming from the wide-angle end to the telephoto end, the first lens group moves, the second lens group moves toward the object, the third lens group moves toward the object, and the fourth lens group moves toward the object. 15. The zoom lens according to configuration 14, wherein the fifth lens group moves toward the object side, and the sixth lens group moves toward the object side.
(Configuration 16)
16. The zoom lens according to any one of configurations 1 to 15, wherein the first lens group moves along a convex trajectory toward the image side during zooming from the wide-angle end to the telephoto end.
(Configuration 17)
The zoom lens according to any one of configurations 1 to 16 (configuration 18), wherein the lens group Fp is composed of a cemented lens of a negative lens and a positive lens.
18. The zoom lens according to any one of configurations 1 to 17, wherein the lens group Fn includes a negative lens.
(Configuration 19)
16. The zoom lens according to configuration 14 or 15, wherein an aperture stop is disposed between the third lens group and the fourth lens group.
(Configuration 20)
An imaging device comprising the zoom lens according to any one of Structures 1 to 19 and an image sensor that receives an image formed by the zoom lens.
(Configuration 21)
20. An imaging system comprising the zoom lens according to any one of Structures 1 to 19, and a control section that controls the zoom lens during zooming.
(Configuration 22)
22. The imaging system according to configuration 21, wherein the control section is configured as a separate body from the zoom lens, and includes a transmission section that transmits a control signal for controlling the zoom lens.
(Configuration 23)
23. The imaging system according to configuration 21 or 22, wherein the control unit is configured as a separate body from the zoom lens, and includes an operation unit for operating the zoom lens.
(Configuration 24)
24. The imaging system according to any one of configurations 21 to 23, further comprising a display unit that displays information regarding zooming of the zoom lens.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the invention.

For example, an element having no refractive power, such as a lens group with weak refractive power or a flat plate, may be arranged on the object side or image side of the zoom lens B0.

Bi ith lens group BR Rear group FP Flare cut diaphragm SP Aperture diaphragm IP Image plane

Claims (24)

It includes a first lens group with negative refractive power and a plurality of lens groups arranged in order from the object side to the image side, and has a rear group with positive refractive power as a whole, and when zooming from the wide-angle end to the telephoto end. A zoom lens in which the distance between adjacent lens groups changes,
The rear group includes a positive refractive power lens group Fp, at least two positive refractive power lens groups, and a negative refractive power lens group Fn arranged in order from the object side to the image side,
The lens group Fp and the lens group Fn move during focusing from infinity to a close distance,
When the entrance pupil position of the zoom lens at the wide-angle end is ENPw, and the focal length of the zoom lens at the wide-angle end is fw,
1.0<ENPw/fw<3.0
A zoom lens characterized by satisfying the following conditional expression. When focusing from infinity to close range, the lens group Fp moves toward the image side,
2. The zoom lens according to claim 1, wherein during zooming from a wide-angle end to a telephoto end, an interval between the lens group Fp and a lens group disposed adjacent to the image side of the lens group Fp narrows. When focusing from infinity to close range, the lens group Fn moves toward the object side,
2. The zoom lens according to claim 1, wherein during zooming from a wide-angle end to a telephoto end, a distance between the lens group Fn and a lens group disposed adjacent to the image side of the lens group Fn increases. The thickness on the optical axis of the lens group with positive refractive power arranged adjacent to the object side of the lens group Fn is Dp, and the light from the lens surface closest to the object side of the zoom lens at the wide-angle end to the image plane When the distance on the axis is Lw,
0.05<Dp/Lw<0.40
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. When the distance on the optical axis from the exit pupil position of the zoom lens to the image plane at the wide-angle end is POw, and the air equivalent length of the back focus of the zoom lens at the wide-angle end is BFw,
2.0<Pow/BFw<6.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. When the focal length of the lens group Fp is fFp,
3.0<fFp/fw<8.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. When the focal length of the lens group Fn is fFn,
-10<fFn/fw<-1
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. When the focal length of a lens group with positive refractive power arranged adjacent to the image side of the lens group Fp is fBa,
4.0<fBa/fw<100.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. When the thickness of the first lens group on the optical axis is D1,
1.0<D1/fw<5.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. The zoom lens according to claim 1, wherein the first lens group includes three or four negative lenses and one positive lens. The first lens group includes a negative meniscus lens L11 disposed closest to the object side of the first lens group and having a convex shape on the object side, and a negative meniscus lens L11 disposed adjacent to the image side of the negative meniscus lens L11 on the object side. The zoom lens according to claim 1, further comprising a convex negative meniscus lens L12. When the refractive index of the negative meniscus lens L11 is N11, and the refractive index of the negative meniscus lens L12 is N12,
0.86<N11/N12<1.00
The zoom lens according to claim 11, wherein the zoom lens satisfies the following conditional expression. The rear group includes a lens group with positive refractive power disposed closest to the image side,
When the back focus of the zoom lens at the wide-angle end is BFw,
0.2<BFw/fw<3.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression. The rear group includes a second lens group with positive refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a negative refractive power, which are arranged in order from the object side to the image side. 2. The zoom lens according to claim 1, comprising a fifth lens group having a positive refractive power and a sixth lens group having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the first lens group moves, the second lens group moves toward the object, the third lens group moves toward the object, and the fourth lens group moves toward the object. 15. The zoom lens according to claim 14, wherein the fifth lens group moves toward the object side, and the sixth lens group moves toward the object side. 2. The zoom lens according to claim 1, wherein during zooming from a wide-angle end to a telephoto end, the first lens group moves along a convex trajectory toward the image side. The zoom lens according to claim 1, wherein the lens group Fp is composed of a cemented lens of a negative lens and a positive lens. The zoom lens according to claim 1, wherein the lens group Fn comprises a negative lens. 15. The zoom lens according to claim 14, wherein an aperture stop is disposed between the third lens group and the fourth lens group. An imaging device comprising: the zoom lens according to any one of claims 1 to 19; and an image sensor that receives an image formed by the zoom lens. An imaging system comprising: the zoom lens according to any one of claims 1 to 19; and a control section that controls the zoom lens during zooming. 22. The imaging system according to claim 21, wherein the control section is configured as a separate body from the zoom lens, and includes a transmission section that transmits a control signal for controlling the zoom lens. 22. The imaging system according to claim 21, wherein the control section is configured as a separate body from the zoom lens, and includes an operation section for operating the zoom lens. The imaging system according to claim 21, further comprising a display unit that displays information regarding zooming of the zoom lens.