JP7542965B2 - Zoom lens and imaging device - Google Patents

Description

The present invention relates to a zoom lens and an imaging device.

In recent years, imaging devices using solid-state imaging elements such as digital still cameras have become widespread. As this popularity spreads, optical systems have become more compact and more powerful, and small imaging device systems are becoming increasingly popular. Such imaging devices are usually equipped with a zoom lens.

For example, as a zoom lens with a focal length wider than 24 mm in 35 mm equivalent (a so-called wide-angle zoom lens), there is known a zoom lens having a first lens group with negative refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and a lens group with negative refractive power on the image side of the third lens group (see, for example, Patent Documents 1 to 3).

JP 2016-133764 A JP 2019-66654 A Japanese Unexamined Patent Publication No. 63-32513

Wide-angle zoom lenses usually tend to have a long overall length. For example, the maximum overall length over the entire zoom range may be 106.5 mm for the zoom lens described in Patent Document 1, 125.4 mm for the zoom lens described in Patent Document 2, and 215.1 mm for the zoom lens described in Patent Document 3.

One aspect of the present invention aims to realize a small, high-performance zoom lens and imaging device.

In order to solve the above problems, a zoom lens according to one aspect of the present invention is composed of L lens groups, where L is an integer greater than or equal to 4, and comprises, in order from the object side, a first lens group having negative refractive power, an intermediate group having one or more lens groups and having a positive composite refractive power, an L-1 lens group having negative refractive power, and an L lens group having negative refractive power, and performs a magnification change operation by changing the spacing between adjacent lens groups, and satisfies the following formula:
-1.200<f ₁ /f _t <-0.804 (1)
1.10<β _L-1w <2.00 (2)
however,
f ₁ : focal length of the first lens group f _t : focal length of the zoom lens at the telephoto end when focused on infinity β _L-1w : lateral magnification of the L-1 lens group at the wide-angle end

In order to solve the above problem, an imaging device according to one aspect of the present invention includes the above zoom lens and an imaging element provided on the image side of the zoom lens, which converts an optical image formed by the zoom lens into an electrical signal.

According to one aspect of the present invention, it is possible to realize a small, high-performance zoom lens and imaging device.

1A and 1B are diagrams illustrating optical configurations of a zoom lens according to a first embodiment when focused on infinity at a wide-angle end and a telephoto end. 4 is a diagram showing longitudinal aberration of the zoom lens of Example 1 when focused on infinity at the wide-angle end. FIG. 4 is a diagram showing longitudinal aberration of the zoom lens of Example 1 when focused on infinity in an intermediate focal length state. FIG. 4 is a diagram showing longitudinal aberration of the zoom lens of Example 1 when focused on an object at infinity at the telephoto end. FIG. 11A and 11B are diagrams illustrating the optical configuration of a zoom lens according to a second embodiment when focused on infinity at a wide-angle end and a telephoto end. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 2 when focused on an object at infinity at the wide-angle end. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 2 when focused on infinity in an intermediate focal length state. FIG. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 2 when focused on an object at infinity at the telephoto end. 11A and 11B are diagrams illustrating optical configurations of a zoom lens according to a third embodiment when focused on infinity at a wide-angle end and a telephoto end. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 3 when focused on an object at infinity at the wide-angle end. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 3 when focused on infinity in an intermediate focal length state. FIG. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 3 when focused on an object at infinity at the telephoto end. 13A and 13B are diagrams illustrating optical configurations of a zoom lens according to a fourth embodiment when focused on infinity at a wide-angle end and a telephoto end. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 4 when focused on an object at infinity at the wide-angle end. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 4 when focused on infinity in an intermediate focal length state. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 4 when focused on an object at infinity at the telephoto end. 13A and 13B are diagrams illustrating optical configurations of a zoom lens according to a fifth embodiment when focused on infinity at a wide-angle end and a telephoto end. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 5 when focused on an object at infinity at the wide-angle end. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 5 when focused on infinity in an intermediate focal length state. FIG. 13A and 13B are diagrams illustrating longitudinal aberration of the zoom lens of Example 5 when focused on an object at infinity at the telephoto end. 13A and 13B are diagrams illustrating optical configurations of a zoom lens according to a sixth embodiment when focused on infinity at a wide-angle end and a telephoto end. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 6 when focused on an object at infinity at the wide-angle end. FIG. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 6 when focused on infinity in an intermediate focal length state. FIG. 13 is a diagram showing longitudinal aberration of the zoom lens of Example 6 when focused on an object at infinity at the telephoto end. FIG. 1 is a diagram illustrating an example of a configuration of an imaging device according to an embodiment of the present invention.

Below, an embodiment of a zoom lens and an imaging device according to the present invention will be described. More specifically, this embodiment relates to an inexpensive zoom lens suitable for the imaging optical system of digital input/output devices such as digital still cameras, digital video cameras, and single-lens reflex cameras that use solid-state imaging elements. It also relates to an interchangeable lens device and an imaging device that have the zoom lens. However, the zoom lens and imaging device described below are one aspect of the zoom lens and imaging device according to the present invention, and the zoom lens and imaging device according to the present invention are not limited to the following aspects.

1. Zoom Lens 1.1 Optical Configuration A zoom lens according to an embodiment of the present invention is composed of, in order from the object side, a first lens group having negative refractive power, an intermediate group having one or more lens groups and having a positive composite refractive power, an L-1th lens group having negative refractive power, and an Lth lens group having negative refractive power. The zoom lens performs a magnification change operation by changing the interval between adjacent lens groups. The zoom lens is composed of L lens groups including at least the lens groups described above. Here, L is an integer equal to or greater than 4. The zoom lens is small and has high performance by appropriately configuring the lens arrangement and power arrangement of the optical system.

In this specification, the term "lens group" refers to a collection of one or more lenses that work together during a magnification change operation. A lens group may be composed of one single lens, or may be composed of multiple single lenses. For example, a lens group may include a cemented lens in which multiple single lenses are integrated without an air gap, or a compound lens in which a single lens and resin are integrated without an air gap. The lenses in a lens group move while maintaining their relative positional relationship during a magnification change operation. A magnification change operation is performed by changing the distance between the lens groups, and the distance between lenses belonging to the same lens group does not change during a magnification change operation.

In this specification, a "lens" refers to a single lens. For example, a cemented lens consisting of two single lenses will be described as two lenses. In this specification, a single lens may be either a spherical lens or an aspherical lens. In addition, an aspherical lens also includes a so-called composite aspherical lens, which has an aspherical film attached to its surface.

(1) First Lens Group The first lens group is the lens group arranged closest to the object in the zoom lens, and has a negative refractive power. The negative refractive power of the first lens group is advantageous for increasing the angle of view and reducing the front lens diameter (the diameter of the lens arranged closest to the object). It is preferable that the first lens group has at least one lens with positive refractive power from the viewpoint of appropriately correcting chromatic aberration or image surface characteristics. In addition, since the first lens group has negative refractive power as a whole, it is sufficient that the first lens group has at least one lens with negative refractive power. It is preferable that the first lens group has two or more lenses with negative refractive power from the viewpoint of appropriately correcting chromatic aberration or spherical aberration at the telephoto end.

Furthermore, it is preferable for the first lens group to be composed of a total of four lenses, three lenses with negative refractive power and one lens with positive refractive power, from the viewpoint of achieving an appropriate balance between high performance and a short overall length.

From the viewpoint of appropriately correcting chromatic aberration, the Abbe number at the d-line of at least one lens having negative refractive power included in the first lens group is preferably greater than 45, more preferably greater than 48, and even more preferably greater than 50. From the viewpoint of appropriately correcting chromatic aberration, the Abbe number at the d-line of at least one lens having negative refractive power included in the first lens group is preferably smaller than 90. From the viewpoint of appropriately correcting chromatic aberration, it is more preferable that the Abbe numbers at the d-line of all lenses having negative refractive power included in the first lens group satisfy the above-mentioned range.

The Abbe number at the d-line of at least one lens having positive refractive power included in the first lens group is not limited, but is preferably smaller than 45 from the viewpoint of appropriately correcting chromatic aberration. Furthermore, the Abbe number at the d-line of at least one lens having positive refractive power included in the first lens group is preferably larger than 35 from the viewpoint of appropriately correcting chromatic aberration. It is more preferable that the Abbe numbers at the d-line of all lenses having positive refractive power included in the first lens group satisfy the above-mentioned range from the viewpoint of appropriately correcting chromatic aberration.

(2) Intermediate group The intermediate group is disposed on the image side of the first lens group and has positive refractive power. The intermediate group has one or more lens groups. The intermediate group has the second lens group closest to the object side. In this embodiment, the optical characteristics of the entire plurality of lens groups are indicated with the word "composite". The intermediate group is disposed adjacent to the first lens group. It is preferable that the composite refractive power of the intermediate group has a positive refractive power, from the viewpoint of appropriately correcting distortion or astigmatism occurring in the first lens group and working favorably for wide-angle. Since the intermediate group has a positive refractive power as a whole, it is sufficient that the intermediate group has at least one lens having a positive refractive power. It is preferable that the intermediate group has two or more lenses having a positive refractive power, from the viewpoint of appropriately correcting chromatic aberration. It is also preferable that the intermediate group has three or more lenses having a positive refractive power, from the viewpoint of appropriately correcting field curvature at the wide-angle end.

In terms of achieving compactness of the zoom lens, it is preferable that in the intermediate group, at least one lens with negative refractive power is arranged on the object side of the lens with positive refractive power. In terms of achieving compactness of the zoom lens, it is more preferable that in the intermediate group, a lens with positive refractive power is arranged on the object side of the lens with negative refractive power closest to the image. Arranging the entrance pupil position as close to the object side as possible at the wide-angle end is effective for achieving compactness in the radial direction. For this reason, it is more preferable that in terms of achieving compactness of the zoom lens, all lenses with negative refractive power are arranged on the object side of the lenses with positive refractive power in the intermediate group.

In addition, when an aspherical lens is used in the intermediate group, which is a lens group with a relatively large diameter, it is preferable to place the aspherical lens closest to the object in the intermediate group, from the viewpoints of appropriately correcting the field curvature, which tends to be insufficient, and shortening the overall length of the zoom lens.

In addition, from the viewpoint of realizing a compact zoom lens, the refractive index at the d-line of the lens having negative refractive power in the intermediate group closest to the image is preferably greater than 1.65, and more preferably greater than 1.70.

In addition, in the intermediate group, it is preferable to place a lens with negative refractive power on the image side of the lens with positive refractive power from the viewpoint of appropriately correcting chromatic aberration at the telephoto end.

Furthermore, a configuration in which the lens with negative refractive power included in the intermediate group and located closest to the object side is cemented to a lens adjacent to said lens and having positive refractive power is preferable from the viewpoint of shortening the overall length by shortening the distance between the lenses. Normally, when the overall length of a zoom lens is shortened, various manufacturing errors such as decentering errors or errors in the air space between single lenses are more likely to occur. The above configuration can reduce the above manufacturing errors compared to a configuration in which a lens with negative refractive power and a lens with positive refractive power are arranged with an air space between them. Therefore, zoom lenses with high optical performance can be manufactured with a good yield.

In the intermediate group, the lens located closest to the image has a small difference in the incidence angle characteristics between off-axis rays and on-axis rays. For this reason, in this embodiment, a higher correction effect for on-axis chromatic aberration can be obtained compared to the correction effect for chromatic aberration for off-axis rays. Therefore, it is preferable that the lens with positive refractive power included in the intermediate group is low-dispersion glass. Also, from the viewpoint of appropriately correcting chromatic aberration, it is preferable that the Abbe number at the d-line is greater than 40.

Placing the aperture inside the intermediate group is preferable in that it reduces the air gap between the lens groups compared to placing the aperture closer to the object or image than the intermediate group, making it possible to advantageously ensure the zoom ratio and focus movement amount.

In addition, placing lenses with positive refractive power on either side of the aperture makes it possible to make the effective diameters of both the object-side and image-side surfaces of the intermediate group smaller relative to the aperture surface, which is preferable from the standpoint of appropriately correcting aberrations with adjacent lens groups.

(3) L-1th Lens Group The inclusion of the L-1th lens group having negative refractive power on the image side of the entire zoom lens is advantageous in shortening the overall length of the zoom lens.

The L-1 lens group is disposed on the image side of the intermediate group and has negative refractive power. It is preferable from the viewpoint of radial compactness that the lens surface closest to the object side of the L-1 lens group has a convex shape toward the object side. The lens surface closest to the object side of the L-1 lens group having a convex shape toward the object side means that the lens surface closest to the object side of the L-1 lens group has positive refractive power. Therefore, the lens surface closest to the object side of the L-1 lens group has a converging effect, thereby achieving radial compactness after that lens surface. In addition, when radial compactness is achieved, the height of the light ray passing through the lens surface becomes lower (the distance from the optical axis of the light ray becomes shorter). Therefore, the amount of aberration caused by component errors and assembly errors of each lens becomes smaller. Therefore, it is preferable from the viewpoint of reducing errors in sensitivity that are likely to occur when the overall length of the zoom lens is shortened that the lens surface closest to the object side of the L-1 lens group has a convex shape toward the object side.

In order to reduce the size of the zoom lens, it is preferable to place a lens group having positive refractive power adjacent to the L-1 lens group on the object side from the viewpoint of reducing the size in the radial direction and increasing the aperture.

(4) Lth Lens Group The Lth lens group is disposed closest to the image side and has negative refractive power. The Lth lens group is disposed adjacent to the L-1th lens group. Having the Lth lens group, which has negative refractive power, closest to the image side in the zoom lens is advantageous for shortening the overall length of the zoom lens. In addition, having the Lth lens group have negative refractive power allows the diameter of the Lth lens group to be small, which is advantageous for the arrangement of mechanical components.

It is preferable that the Lth lens group has at least one lens having negative refractive power. Having a lens having negative refractive power is preferable from the viewpoint of achieving improved image surface quality or reduced chromatic aberration. It is preferable that the Lth lens group has negative refractive power from the viewpoint of being able to cancel out the curvature of field or distortion occurring in the intermediate group.

(5) Focus Group The zoom lens may have a focus group. In the zoom lens, focusing may be performed using the focus group. In this case, at least one lens in the zoom lens may be moved in the optical axis direction. The focus group is preferably the whole or a part of the L-1th lens group or the Lth lens group.

The focus group is preferably composed of one single lens, one cemented lens, or one compound lens. In such a configuration, the focus group does not include an air gap. Therefore, a zoom lens with this configuration can reduce the size and weight of the focus group compared to a zoom lens with a focus group composed of multiple single lenses arranged with air gaps between them. As a result, the mechanical member (hereinafter referred to as the "focus drive mechanism") for moving the focus group in the optical axis direction when focusing can be reduced in size and weight, and the entire imaging device equipped with the zoom lens can be reduced in size and weight. Note that the imaging device includes, in addition to the zoom lens, a drive mechanism for relatively moving each lens group when changing magnification or the focus drive mechanism, as well as a lens barrel that houses these.

Furthermore, if the L-1th lens group or the Lth lens group, or the whole or part of it, includes a focus group, it is preferable that the focus group has negative refractive power. By having the focus group have negative refractive power, the field curvature or distortion aberration that occurs in the intermediate group having positive refractive power can be offset by the focus group. This makes it possible to obtain a zoom lens with high optical performance.

Note that multiple lens groups or a part of multiple lens groups may be used as the focus group. In other words, focusing may be achieved using a floating method. Using a floating method is preferable from the perspective of improving performance, since it allows for appropriate correction of spherical aberration or image surface quality during close focusing.

(6) Aperture The arrangement of the aperture is not limited in the zoom lens. However, the aperture here refers to the aperture that determines the diameter of the light beam of the zoom lens, that is, the aperture that determines the F-number of the zoom lens.

For example, the aperture may be located within the intermediate group, or on the image side of the intermediate group. Placing an aperture inside the intermediate group is preferable from the viewpoint of reducing the air gap between the lens groups and advantageously ensuring the zoom ratio and focus movement amount. Placing an aperture on the image side of the intermediate group is preferable from the viewpoint of reducing the size of the aperture. Because the magnification change effect of the intermediate group is relatively large, the variation in the diameter of the light beam incident on the intermediate group is small. Therefore, placing an aperture on the image side of the intermediate group is advantageous for reducing the size of the aperture diameter and can suppress the variation in the aperture diameter.

(7) Lens Group Configuration The zoom lens comprises, in order from the object side, a first lens group having negative refractive power, an intermediate group having positive refractive power, an L-1 lens group having negative refractive power, and an L lens group having negative refractive power. Specifically, no other lens groups are included between the first lens group and the intermediate group, between the intermediate group and the L-1 lens group, and between the L-1 lens group and the L lens group, but this does not exclude optical elements such as filters or diaphragms.

1-2. Operation (1) Operation during magnification change In this zoom lens, at least the air space between the lens groups is changed when changing magnification from the wide-angle end to the telephoto end. Also, when changing magnification from the wide-angle end to the telephoto end, the air space between the first lens group and the intermediate group may be changed so as to decrease. Changing in this manner is preferable from the viewpoint of ensuring a desired magnification ratio. Also, the air space between the intermediate group and the L-1th lens group may be changed so as to decrease. Changing in this manner is preferable from the viewpoint of appropriately correcting the curvature of field during zoom fluctuation.

In addition, when changing magnification from the wide-angle end to the telephoto end, it is preferable that the first lens group moves toward the image side. It is also preferable that the first lens group is positioned so that the total length at the wide-angle end is longer than the total length at the telephoto end.

In addition, when changing magnification from the wide-angle end to the telephoto end, at least one of the other lens groups, the L-1 lens group, and the L lens group arranged between the intermediate group and the L-1 lens group may be moved toward the object side. By moving in this manner, the magnification change action of at least one of the other lens groups, the L-1 lens group, and the L lens group can be increased. This leads to dispersing the magnification change action of the intermediate group to the magnification change action of at least one of the other lens groups, the L-1 lens group, and the L lens group, and the magnification change burden of the intermediate group can be further reduced. Therefore, even if the intermediate group does not have a strong refractive power or a large amount of movement, it is possible to achieve a compact zoom lens. Here, the L-1 lens group only needs to be located on the object side at the telephoto end compared to the wide-angle end. Furthermore, if the L-1 lens group is moved toward the object side from the wide-angle end to the telephoto end, the effect of increasing the magnification change action of the L lens group is generated throughout the entire zoom range, which is preferable from the viewpoint of compact zoom lens.

When changing magnification from the wide-angle end to the telephoto end, it is preferable to move all lens groups from the middle group onwards towards the object side. By moving them in this way, it is possible to increase the magnification changing effect of all lens groups from the middle group onwards.

When changing magnification from the wide-angle end to the telephoto end, the air gap between the L-1th lens group and the Lth lens group may be changed so as to decrease.

By doing the above, high performance is achieved for the zoom lens, but the operation of the zoom lens when changing magnification is not limited to the above-mentioned operation.

(2) Operation during focusing In this zoom lens, focusing can be performed by the focus group described above. The focus group that moves when focusing from infinity to a close object can be any lens or lens group as described above. In addition, the direction of movement of the focus group during focusing is not limited.

1-3. Equations Expressing the Conditions of the Zoom Lens It is preferable that the zoom lens according to this embodiment employs the above-mentioned configuration and satisfies at least one of the following equations.

-1.200<f ₁ /f _t <-0.804 (1)
however,
f ₁ : focal length of the first lens group f _t : focal length of the zoom lens at the telephoto end when focused at infinity

Formula (1) is a formula for specifying the ratio between the focal length of the first lens group and the focal length at the telephoto end of the zoom lens when focusing at infinity. Satisfying formula (1) allows the refractive power of the first lens group to be within an appropriate range, which is preferable from the viewpoint of realizing high performance and compactness of the zoom lens. On the other hand, if the lower limit of formula (1) is exceeded, the refractive power of the first lens group may become too small. As a result, the total optical length at the telephoto end becomes long, which may make it difficult to achieve compactness. Also, if the upper limit of formula (1) is exceeded, the refractive power of the first lens group may become too large. As a result, spherical aberration or curvature of field occurs at the telephoto end, which may make it difficult to achieve high performance.

From the viewpoint of realizing a compact zoom lens, f ₁ /f _t is more preferably greater than -1.17, even more preferably greater than -1.14, even more preferably greater than -1.10, even more preferably greater than -1.05, and even more preferably greater than -1.00. Also, from the viewpoint of realizing high performance, f ₁ /f _t is more preferably less than -0.81, even more preferably less than -0.82, even more preferably less than -0.85, and even more preferably less than -0.90.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
1.10<β _L-1w <2.00 (2)
however,
β _L-1w : lateral magnification of the L-1 lens group at the wide-angle end

Formula (2) is a formula for defining the lateral magnification of the L-1th lens group at the wide-angle end. Satisfying formula (2) is preferable from the viewpoint of achieving a wider angle and a shorter overall length. On the other hand, if the lower limit of formula (2) is exceeded, the effect of widening the angle of view of the light rays is weak, and it may be difficult to achieve a wider angle. If the upper limit of formula (2) is exceeded, the lens will have a strong refractive power, making it difficult to correct aberrations with a small number of lenses, and it may be difficult to achieve a shorter overall length of the zoom lens.

From the viewpoint of realizing a wider angle, β _L-1w is more preferably greater than 1.20, even more preferably greater than 1.25, even more preferably greater than 1.30, even more preferably greater than 1.35, and even more preferably greater than 1.41. Also, from the viewpoint of realizing a shorter overall length of the zoom lens, β _L-1w is more preferably less than 1.80, even more preferably less than 1.75, even more preferably less than 1.67, and even more preferably less than 1.60.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
-8.4<f _L-1 /f _t <-0.7 (3)
however,
f _L-1 : focal length of the L-1 lens group f _t : focal length of the zoom lens at the telephoto end when focusing on infinity

Formula (3) is a formula for specifying the ratio between the focal length of the L-1 lens group and the focal length at the telephoto end when the zoom lens is focused at infinity. Satisfying formula (3) is preferable from the viewpoint of realizing a wider angle and a shorter overall length of the zoom lens. In contrast, if the lower limit of formula (3) is exceeded, the effect of widening the angle of view of the light rays is weak, and it may be difficult to realize a wider angle. In addition, it may have a strong refractive power, and it may be difficult to correct aberrations with a small number of lenses. For this reason, it may be difficult to realize a shorter overall length of the zoom lens. If the upper limit of formula (3) is exceeded, it may have a strong refractive power, and it may be difficult to correct aberrations with a small number of lenses. For this reason, it may be difficult to realize a shorter overall length of the zoom lens.

From the viewpoint of realizing a reduction in the overall length of the zoom lens, f _L-1 /f _t is more preferably greater than -2.50, even more preferably greater than -2.30, even more preferably greater than -2.20, even more preferably greater than -2.05, and even more preferably greater than -2.00. Also, from the viewpoint of realizing a wider angle, f _L-1 /f _t is more preferably less than -1.20, even more preferably less than -1.40, even more preferably less than -1.60, and even more preferably less than -1.65.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.5<f _w /Y _imw <5.0 (4)
however,
Y _imw : Maximum image height at the wide-angle end of the zoom lens when focused at infinity f _w : Focal length at the wide-angle end of the zoom lens when focused at infinity

Equation (4) is an equation for specifying the focal length at the wide-angle end of a zoom lens when focused at infinity, relative to the image height at the wide-angle end of the zoom lens when focused at infinity. Satisfying equation (4) is preferable from the perspective of achieving a wider angle and shortening the overall length of the zoom lens. On the other hand, if the lower limit of equation (4) is exceeded, the lens will have a strong refractive power, and it may be difficult to correct aberrations with a small number of lenses. This may make it difficult to shorten the overall length of the zoom lens. If the upper limit of equation (4) is exceeded, the focal length will not have a strong effect of widening the angle of view, and it may be difficult to achieve a wider angle.

From the viewpoint of realizing a reduction in the overall length of the zoom lens, _fw / _Yimw is more preferably greater than 0.6, even more preferably greater than 0.7, even more preferably greater than 0.8, even more preferably greater than 0.9, and even more preferably greater than 1.0. Also, from the viewpoint of realizing a wider angle, _fw / _Yimw is more preferably less than 4.8, even more preferably less than 4.6, even more preferably less than 4.4, and even more preferably less than 4.2.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.6<D _g1pw /f _w <1.3 (5)
however,
D _g1pw : The distance on the optical axis between the lens surface in the first lens group closest to the image side and the lens surface in the intermediate group closest to the object side at the wide-angle end when the zoom lens is focused at infinity. f _w : The focal length of the zoom lens at the wide-angle end when the zoom lens is focused at infinity.

Equation (5) is an equation for specifying the distance on the optical axis between the lens surface of the first lens group closest to the image and the lens surface of the intermediate group closest to the object at the wide-angle end of the zoom lens when focused at infinity, relative to the focal length at the wide-angle end of the zoom lens when focused at infinity. Satisfying equation (5) is preferable from the viewpoint of achieving a wider angle and a shorter overall length. On the other hand, if the lower limit of equation (5) is exceeded, the effect of astigmatism becomes weaker, making it difficult to achieve a wider angle. If the upper limit of equation (5) is exceeded, the effective diameter of the first lens group may become too large. This may make it difficult to achieve a compact zoom lens.

From the viewpoint of realizing a wider angle, D _g1pw /f _w is more preferably greater than 0.65, even more preferably greater than 0.70, even more preferably greater than 0.80, even more preferably greater than 0.90, and even more preferably greater than 1.00. From the viewpoint of realizing a compact zoom lens, D _g1pw /f _w is more preferably less than 1.20, even more preferably less than 1.10, even more preferably less than 1.05, and even more preferably less than 1.00.

In the zoom lens according to this embodiment, it is preferable that the first lens group has at least one lens having positive refractive power and satisfies the following formula:
1.58<N _dLP1 <2.20 (6)
however,
N _dLP1 : Refractive index at the d line of a lens having a positive refractive power

Equation (6) is an equation for defining the refractive index at the d-line of the lens having positive refractive power included in the first lens group. In the first lens group having negative refractive power, it is common to use a relatively high refractive index glass as the lens having negative refractive power and a low refractive index glass as the lens having positive refractive power to correct the Petzval sum. Satisfying equation (6) is preferable from the viewpoint of achieving low costs while ensuring good image surface quality. On the other hand, if the lower limit of equation (6) is not met, it may be difficult to properly correct the Petzval sum. If the upper limit of equation (6) is exceeded, it may be difficult to properly correct the field curvature because a material with a higher refractive index cannot be applied to the lens having negative refractive power.

From the viewpoint of appropriately correcting the Petzval sum, _NdLP1 is more preferably greater than 1.60, even more preferably greater than 1.61, and even more preferably greater than 1.62. From the viewpoint of appropriately correcting the field curvature, _NdLP1 is more preferably less than 2.00, even more preferably less than 1.90, even more preferably less than 1.85, and even more preferably less than 1.80.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.10<f _12w /f _w <0.80 (7)
however,
_f12w : composite focal length of the first lens group and the second lens group at the wide-angle end when the zoom lens is focused at infinity _fw : focal length of the zoom lens at the wide-angle end when the zoom lens is focused at infinity

Equation (7) is an equation for specifying the composite focal length of the first lens group and the second lens group at the wide-angle end when the zoom lens is focused at infinity, relative to the focal length at the wide-angle end when the zoom lens is focused at infinity. In order to reduce the overall length, it is preferable that the lens group located on the object side has a large power. Also, in order to maintain high resolution, it may not be desirable for the power to be too large. Satisfying equation (7) is preferable from the viewpoint of achieving high resolution while ensuring a short overall length. On the other hand, if the lower limit of equation (7) is exceeded, it may be difficult to achieve high resolution. If the upper limit of equation (7) is exceeded, it may be difficult to reduce the overall length of the zoom lens.

From the viewpoint of realizing high resolution, _f12w / _fw is more preferably greater than 0.15, even more preferably greater than 0.20, even more preferably greater than 0.25, even more preferably greater than 0.30, and even more preferably greater than 0.35. Also, from the viewpoint of realizing a reduction in the overall length of the zoom lens, _f12w / _fw is more preferably less than 0.67, even more preferably less than 0.64, even more preferably less than 0.60, and even more preferably less than 0.55.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.001<D _Lt /f _t <0.770 (8)
however,
D _Lt : The distance on the optical axis between the lens surface closest to the object in the Lth lens group and the lens surface closest to the image in the L-1th lens group at the telephoto end when the zoom lens is focused at infinity. f _t : The focal length of the zoom lens at the telephoto end when the zoom lens is focused at infinity.

Equation (8) is an equation for specifying the distance on the optical axis between the lens surface of the Lth lens group closest to the object and the lens surface of the L-1th lens group closest to the image at the telephoto end of the zoom lens when focusing at infinity, relative to the focal length at the telephoto end of the zoom lens when focusing at infinity. Placing the Lth lens group having negative refractive power closest to the image side is advantageous for shortening the overall length of the zoom lens at the telephoto end, and also allows for appropriate correction of spherical aberration and curvature of field at the telephoto end. Satisfying equation (8) is preferable from the viewpoint of achieving an appropriate zoom magnification while ensuring a short overall length. On the other hand, if the lower limit of equation (8) is exceeded, it may be difficult to appropriately correct spherical aberration and curvature of field at the telephoto end while maintaining an appropriate back focus (BF). If the upper limit of equation (8) is exceeded, it may be difficult to achieve a shortened overall length of the zoom lens.

From the viewpoint of appropriately correcting spherical aberration and curvature of field at the telephoto end while maintaining an appropriate back focus, D _Lt /f _t is more preferably greater than 0.020, even more preferably greater than 0.030, even more preferably greater than 0.050, and even more preferably greater than 0.070. Also, from the viewpoint of realizing a reduction in the overall length of the zoom lens, D _Lt /f _t is more preferably less than 0.750, even more preferably less than 0.700, even more preferably less than 0.600, and even more preferably less than 0.550.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.001< _DLw / _fw <0.900...(9)
however,
D _Lw : The distance on the optical axis between the lens surface closest to the object in the Lth lens group and the lens surface closest to the image in the L-1th lens group at the wide-angle end when the zoom lens is focused at infinity. f _w : The focal length of the zoom lens at the wide-angle end when the zoom lens is focused at infinity.

Equation (9) is an equation for specifying the distance on the optical axis between the lens surface of the Lth lens group closest to the object and the lens surface of the L-1th lens group closest to the image at the wide-angle end of the zoom lens when focusing at infinity, relative to the focal length at the wide-angle end of the zoom lens when focusing at infinity. Arranging the Lth lens group having negative refractive power further back is advantageous for shortening the overall length of the zoom lens at the wide-angle end. Satisfying equation (9) is preferable from the viewpoint of ensuring a short overall length while maintaining an appropriate back focus. On the other hand, if the lower limit of equation (9) is exceeded, it may be difficult to achieve a shortened overall length of the zoom lens at the wide-angle end. If the upper limit of equation (9) is exceeded, it may be difficult to maintain an appropriate back focus.

From the viewpoint of realizing a reduction in the overall length of the zoom lens at the wide-angle end, D _Lw /f _w is more preferably greater than 0.020, even more preferably greater than 0.030, even more preferably greater than 0.050, and even more preferably greater than 0.070. Also, from the viewpoint of maintaining an appropriate back focus, D _Lw /f _w is more preferably less than 0.850, even more preferably less than 0.800, even more preferably less than 0.750, and even more preferably less than 0.700.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.03<D _g1pt / _ft <0.20 (10)
however,
D _g1pt : The distance on the optical axis between the lens surface in the first lens group closest to the image side and the lens surface in the intermediate group closest to the object side at the telephoto end when the zoom lens is focused at infinity. f _t : The focal length of the zoom lens at the telephoto end when the zoom lens is focused at infinity.

Equation (10) is an equation for specifying the distance on the optical axis between the lens surface of the first lens group closest to the image and the lens surface of the intermediate group closest to the object at the telephoto end of the zoom lens when focused at infinity, relative to the focal length at the telephoto end of the zoom lens when focused at infinity. Satisfying the upper limit of equation (10) is preferable from the viewpoint of shortening the overall length of the zoom lens. Satisfying equation (10) is preferable from the viewpoint of realizing a shortened overall length of the zoom lens while maintaining an appropriate zoom magnification. On the other hand, if the lower limit of equation (10) is exceeded, it may be difficult to maintain an appropriate zoom magnification. If the upper limit of equation (10) is exceeded, it may be difficult to realize a shortened overall length of the zoom lens.

From the viewpoint of maintaining an appropriate zoom magnification, D _g1pt /f _t is more preferably greater than 0.033, even more preferably greater than 0.038, even more preferably greater than 0.040, and even more preferably greater than 0.043. Also, from the viewpoint of realizing a reduction in the overall length of the zoom lens, D _g1pt /f _t is more preferably less than 0.170, even more preferably less than 0.140, and even more preferably less than 0.130.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
L _max / Y _imw <5...(11)
however,
L _max : Maximum overall length over the entire zoom range (the distance from the lens surface closest to the object to the image plane)
Y _imw : Maximum image height at the wide-angle end of the zoom lens when focused at infinity

Equation (11) is an equation for specifying the maximum overall length of the zoom lens over the entire zoom range for the image height at the wide-angle end when the zoom lens is focused at infinity. Satisfying equation (11) is preferable from the perspective of realizing a reduction in the overall length of the zoom lens for the image height. If the upper limit of equation (11) is exceeded, it may become difficult to reduce the overall length of the zoom lens.

From the viewpoint of realizing a reduction in the overall length of the zoom lens, _Lmax / _Yimw is more preferably less than 4.6, even more preferably less than 4.5, and even more preferably less than 4.4. From the viewpoint of realizing high performance, _Lmax / _Yimw is preferably more than 3.0.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
f _t /f _w >1.3 (12)
however,
f _t : focal length at the telephoto end of the zoom lens when focused at infinity f _w : focal length at the wide-angle end of the zoom lens when focused at infinity

Equation (12) is an equation for specifying the ratio (zoom ratio) between the focal length of a zoom lens at the wide-angle end when focused on infinity and the focal length of a zoom lens at the telephoto end when focused on infinity. Satisfying equation (12) is preferable from the viewpoint of achieving a zoom ratio equal to or greater than the specified value. If the lower limit of equation (12) is not satisfied, it may be difficult to ensure a zoom ratio equal to or greater than the specified value.

From the viewpoint of ensuring a zoom ratio equal to or greater than the specified level, f _t /f _w is preferably greater than 1.4, more preferably greater than 1.5, and even more preferably greater than 1.55. From the viewpoint of realizing a compact zoom lens, f _t /f _w is preferably less than 6.0, more preferably less than 4.0, and even more preferably less than 3.0.

It is preferable that the zoom lens according to this embodiment satisfies the following formula:
0.01<f _L-1 /f _L <1.0 (13)
however,
f _L-1 : focal length of the L-1th lens group f _L : focal length of the Lth lens group

Equation (13) is an equation for defining the ratio between the focal length of the Lth lens group and the focal length of the L-1th lens group. Satisfying equation (13) is preferable from the viewpoint of realizing a reduction in the overall length of the zoom lens. If the lower limit of equation (13) is not satisfied, it may become difficult to maintain an appropriate back focus. If the upper limit of equation (13) is exceeded, it may become difficult to reduce the overall length of the zoom lens.

From the viewpoint of realizing a reduction in the overall length of the zoom lens, f _L-1 /f _L is more preferably greater than 0.02, even more preferably greater than 0.03, and even more preferably greater than 0.04. Also, f _L-1 /f _L is more preferably less than 0.90, even more preferably less than 0.80, and even more preferably less than 0.75.

2. Imaging Device Next, an imaging device according to an embodiment of the present invention will be described. The imaging device includes the zoom lens according to the above embodiment and an imaging element provided on the image plane side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

Here, the imaging element is not limited, and solid-state imaging elements such as CCD (Charge Coupled Device) sensors and CMOS (Complementary Metal Oxide Semiconductor) sensors, silver halide film, etc. can also be used. The imaging device according to this embodiment is suitable for imaging devices using the above-mentioned solid-state imaging elements, such as digital cameras and video cameras. The imaging device may be a fixed-lens imaging device in which the lens is fixed to the housing, or a lens-interchangeable imaging device such as a single-lens reflex camera or a mirrorless single-lens camera. In particular, the zoom lens according to this embodiment can ensure a back focus suitable for an interchangeable lens system. Therefore, it is suitable for imaging devices such as single-lens reflex cameras equipped with an optical finder, a phase difference sensor, and a reflex mirror for branching light to these.

Fig. 25 is a diagram showing a schematic example of the configuration of an imaging device according to this embodiment. As shown in Fig. 25, a mirrorless single-lens camera 1 has a body 2 and a lens barrel 3 that is detachable from the body 2. The mirrorless single-lens camera 1 is one form of an imaging device.

The lens barrel 3 has a zoom lens 30. The zoom lens 30 includes a first lens group 31, a second lens group 32, a third lens group 33, and a fourth lens group 34, and is configured to satisfy, for example, the above-mentioned expressions (1) and (2). An aperture 35 is disposed within the second lens group.

The first lens group 31 has negative refractive power, and the second lens group 32 has positive refractive power. The third lens group 33 has negative refractive power, and the fourth lens group 34 has negative refractive power. The third lens group 33 corresponds to the aforementioned L-1 lens group, and the fourth lens group 34 corresponds to the aforementioned L lens group.

The main body 2 has a CCD sensor 21 as an image sensor and a cover glass 22. The CCD sensor 21 is disposed in the main body 2 at a position where the optical axis OA of the zoom lens 30 in the lens barrel 3 attached to the main body 2 is the central axis. The main body 2 may have a parallel plate that has no substantial refractive power instead of the cover glass 22.

It is more preferable that the imaging device according to this embodiment has an image processing section that electrically processes the captured image data acquired by the imaging element to change the shape of the captured image, and an image correction data storage section that stores image correction data and an image correction program used to process the captured image data in the image processing section.

When a zoom lens is made smaller, distortion (curvature) of the captured image shape formed on the imaging plane is more likely to occur. In such cases, it is preferable to correct the distortion of the captured image shape. This correction can be performed, for example, by storing distortion correction data for correcting the distortion of the captured image shape in advance in an image correction data storage unit, and using the distortion correction data stored in the image correction data storage unit in the image processing unit. With such an imaging device, it is possible to further miniaturize the zoom lens, obtain a beautiful captured image, and miniaturize the entire imaging device.

Furthermore, in the imaging device according to this embodiment, it is preferable to have the image correction data storage unit store magnification chromatic aberration correction data in advance. It is also preferable that the image processing unit performs magnification chromatic aberration correction of the captured image using the magnification chromatic aberration correction data stored in the image correction data storage unit. By correcting the magnification chromatic aberration, i.e., color distortion aberration, with the image processing unit, it is possible to reduce the number of lenses that make up the optical system. Therefore, with such an imaging device, it is possible to further miniaturize the zoom lens, obtain a beautiful captured image, and miniaturize the entire imaging device.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention.

An embodiment of the present invention will be described below. In the following tables, all lengths are in mm, all angles of view are in degrees, and "E+a" indicates "×10 ^a ."

[Example 1]
FIG. 1 is a diagram showing the optical configuration of the zoom lens of Example 1 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 1 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed in the second lens group G2. "IMG" shown in FIG. 1 is an image plane (image forming plane), and a cover glass CG is disposed between the fourth lens group G4 and the image plane IMG. "F" in FIG. 1 indicates a focus group, and in the zoom lens of Example 1, the third lens group G3 is the focus group.

The zoom lens of Example 1 performs a magnification change operation by changing the air gap between each lens group. When focusing from an object at infinity to a close object, the third lens group G3 moves toward the image side along the optical axis. The air gap between the first lens group G1 and the second lens group G2 is the largest among the air gaps at the wide-angle end when the zoom lens is focused on an object at infinity.

The configuration of each lens group will be described below. The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex shape toward the object side, a negative meniscus lens L2 with a convex shape toward the object side, a biconcave lens L3, and a positive meniscus lens L4 with a convex shape toward the object side.

The second lens group G2 is composed of, in order from the object side, a cemented lens in which a negative meniscus lens L5 with a convex shape toward the object side and a biconvex lens L6 are cemented together, a stop S, a biconvex lens L7, and a cemented lens in which a negative meniscus lens L8 with a convex shape toward the object side and a positive meniscus lens L9 with a convex shape toward the object side are cemented together. The second lens group G2 corresponds to the intermediate group described above.

The third lens group G3 is composed of a positive meniscus lens L10 that is convex toward the object side. The third lens group G3 corresponds to the aforementioned L-1 lens group.

The fourth lens group G4 is composed of, in order from the object side, a positive meniscus lens L11 with a convex shape toward the image side and a negative meniscus lens L12 with a convex shape toward the image side. The fourth lens group G4 corresponds to the Lth lens group described above.

The zoom lens of Example 1 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 1, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, and the fourth lens group G4 gradually moves toward the object side relative to the image surface.

Next, we will explain an example in which specific numerical values of a zoom lens are applied. Table 1 is a table of surface data for the zoom lens in Example 1.

In the surface data table, "Surface No." indicates the order of the lens surface counted from the object side, "r" indicates the radius of curvature of the lens surface, "d" indicates the distance on the optical axis of the lens surfaces, "Nd" indicates the refractive index for the d-line (wavelength λ=587.56 nm), and "vd" indicates the Abbe number for the d-line. In addition, the "*" mark in the surface number indicates that the lens surface is aspheric, and the "S" mark indicates that it is an aperture. Furthermore, marks such as "d8" and "d17" in the "d" column indicate that the distance on the optical axis of the lens surfaces is a variable distance that changes when changing magnification or focusing.

Note that "INF" in the radius of curvature means a flat surface. In Table 1, Nos. 1 to 8 are surface numbers of the first lens group G1. Nos. 9 to 17 are surface numbers of the second lens group G2, and No. 12 represents the aperture. Nos. 18 and 19 are surface numbers of the third lens group G3, and Nos. 20 to 23 are surface numbers of the fourth lens group G4. Nos. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

[Table 1]
Surface No. rd Nd vd
1 40.135 1.800 1.7292 54.67
2 15.385 3.420
3＊ 173.754 1.700 1.6935 53.19
4* 42.505 8.046
5 -58.952 1.000 1.4970 81.61
6 39.912 0.100
7 25.897 5.410 1.6200 36.26
8 3524.603 d8
9＊ 44.534 0.800 1.6730 38.15
10 12.983 6.215 1.6177 49.82
11 -198.81 2.730
12S INF 1.868
13 47.675 6.042 1.5378 74.70
14 -21.388 0.150
15 19.859 0.800 1.8830 40.81
16 11.092 5.484 1.4970 81.61
17 209.717 d17
18 48.092 0.700 1.4875 70.24
19 15.996 d19
20 -1.83003E+16 3.710 1.6239 35.96
21 -26.646 0.388
22＊ -19.179 0.700 1.6889 31.16
23* -95.557 d23
24 INF 2.500 1.5168 64.20
25 INF 1.000
26 INF

Table 2 shows the specifications of the zoom lens of Example 1. In the specifications, "f" represents the focal length of the zoom lens, "Fno." represents the F-number, "ω" represents the half angle of view, and "Y" represents the image height. In addition, in the specifications, "dn" (n is an integer) represents the variable distance on the optical axis of the zoom lens when changing the magnification. The three columns on the left side of the specifications show, from left to right, the values at the wide-angle end, the intermediate focal length state, and the telephoto end when focusing on infinity. In addition, the three columns on the right side of the specifications show, from left to right, the values at the wide-angle end when the object distance is 170.00 mm, the values at the intermediate focal length state when the object distance is 180.00 mm, and the values at the telephoto end when the object distance is 184.34 mm. These object distances are the shortest imaging distances at each focal length.

[Table 2]
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.0027 21.4889 26.9171 16.3832 19.0116 25.2095
Fno 2.8177 2.8327 2.8386 1.8123 2.1395 2.9048
ω 52.0600 44.6390 37.7657 51.5366 44.0063 37.1304
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 15.9586 8.4765 2.5776 15.9586 8.4765 2.5776
d17 0.9825 0.6343 0.4585 1.9943 1.9271 2.0901
d19 11.2972 12.5114 13.6067 10.2660 25.1122 11.2078
d23 10.1989 13.5549 17.6673 10.1989 13.5549 17.6673

Table 3 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 1. The aspheric coefficients in this table are values when each aspheric surface shape is defined by the following formula.
^{[ Formula ] ​ ​ ​ ​ ​ ​}

In the above formula, "X" is the amount of displacement from the reference surface in the optical axis direction, "C" is the curvature at the vertex of the surface, "Y" is the height from the optical axis in a direction perpendicular to the optical axis, "K" is the Conic coefficient, and "An" is the n-th order aspheric coefficient.

[Table 3]
Surface No. k A4 A6
3 2.000000E+00 2.347730E-04 -1.286710E-06
4 2.300000E+00 2.470640E-04 -1.060730E-06
9 0.000000E+00 -3.186230E-05 -9.036370E-08
22 0.000000E+00 8.644780E-05 -5.450870E-07
23 0.000000E+00 9.090640E-05 -7.088930E-07
Face No. A8 A10 A12
3 6.768780E-09 -1.781330E-11 2.286940E-14
4 3.538520E-09 1.144950E-11 -6.916670E-14
9 -1.406260E-10 -1.607200E-12 0.000000E+00
22 2.516750E-09 1.687900E-12 0.000000E+00
23 3.979070E-09 -8.440930E-12 0.000000E+00

Table 4 shows the focal length of each lens group that constitutes the zoom lens of Example 1.

[Table 4]
Lens Group No. Focal length of lens group
1 -26.813
2 19.514
3 -49.519
4 -200.013

Table 5 shows the overall length of the zoom lens of Example 1 at the wide-angle end and telephoto end when focused on infinity.

[Table 5]
Overall length Wide-angle end 92.998
Telephoto end 88.871

Figures 2, 3, and 4 are diagrams showing longitudinal aberrations of the zoom lens of Example 1 at the wide-angle end, in the intermediate focal length state, and when focusing on infinity at the telephoto end, respectively. The longitudinal aberration diagrams shown in each figure are, from the left as you face the drawing, spherical aberration (mm), astigmatism (mm), and distortion aberration (%), respectively. The same applies to the other examples.

In the graph showing spherical aberration, the vertical axis represents the ratio to the maximum aperture F-number, and the horizontal axis represents defocus. In the graph showing spherical aberration, the solid line represents spherical aberration at the d-line (wavelength λ=587.56 nm), the dashed line represents spherical aberration at the F-line (wavelength λ=486.13 nm), and the dotted line represents spherical aberration at the C-line (wavelength λ=656.28 nm).

In the diagram showing astigmatism, the vertical axis represents image height (mm) and the horizontal axis represents defocus. In the diagram showing astigmatism, the solid line represents the sagittal image plane (S) for the d-line, and the four-dot chain line represents the meridional image plane (T) for the d-line.

In the diagram showing distortion aberration, the vertical axis is image height (mm) and the horizontal axis is %. Note that "IMG HT" in the aberration diagram represents image height.

[Example 2]
5 is a diagram showing a schematic optical configuration of the zoom lens of Example 2 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 2 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed in the second lens group G2. A cover glass CG is disposed between the fourth lens group G4 and the image surface IMG. The second lens group G2 corresponds to the intermediate group described above. The third lens group G3 corresponds to the L-1th lens group described above. The fourth lens group G4 corresponds to the Lth lens group described above.

The zoom lens of Example 2 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 2, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, and the fourth lens group G4 gradually moves toward the object side relative to the image surface.

Table 6 is a table of surface data for the zoom lens of Example 2. In Table 6, No. 1 to 8 are surface numbers of the first lens group G1. No. 9 to 17 are surface numbers of the second lens group G2, and No. 12 represents the aperture. No. 18 and 19 are surface numbers of the third lens group G3, and No. 20 to 23 are surface numbers of the fourth lens group G4. No. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

[Table 6]
Surface No. rd Nd vd
1 40.135 1.800 1.7292 54.67
2 15.385 3.420
3＊ 116.465 1.700 1.6935 53.19
4* 40.366 8.400
5 -54.705 1.000 1.4970 81.61
6 42.439 0.276
7 27.351 5.410 1.6200 36.26
8 -360165.589 d8
9＊ 37.191 0.800 1.6730 38.15
10 12.614 6.354 1.6278 58.89
11 -172.301 1.456
12S INF 3.363
13 41.310 5.498 1.5915 54.30
14 -24.112 0.150
15 18.238 0.800 1.8830 40.81
16 9.764 4.702 1.4970 81.61
17 34.677 d17
18 49.918 0.700 1.4875 70.41
19 17.858 d19
20 -78.475 3.839 1.4875 70.41
21 -21.495 0.630
22＊ -14.381 0.700 1.6889 31.16
23* -23.276 d23
24 INF 2.500 1.5168 64.20
25 INF 1.000
26 INF

Table 7 shows the specifications of the zoom lens of Example 2. Table 8 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 2. Table 9 shows the focal length of each lens group constituting the zoom lens of Example 2. Table 10 shows the overall length of the zoom lens of Example 2 at the wide-angle end and the telephoto end when focused on infinity.

[Table 7]
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.4441 21.9143 27.3643 16.8654 20.9210 25.6826
Fno 2.8908 2.8888 2.8858 1.8615 2.3489 2.9481
ω 52.2541 44.7592 37.8636 51.6208 43.9945 37.0291
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 17.4696 9.6896 3.4996 17.4696 9.6896 3.4996
d17 0.7432 0.6245 0.7308 2.0263 2.3065 2.9234
d19 6.1461 7.7219 8.4074 4.8629 6.0399 6.2148
d23 15.1422 17.8762 22.0973 15.1422 17.8762 22.0973

[Table 8]
Surface No. k A4 A6
3 -1.559950E-12 2.244770E-04 -1.227370E-06
4 -9.565640E-13 2.372070E-04 -1.042790E-06
9 0.000000E+00 -2.911790E-05 -9.172420E-08
22 0.000000E+00 1.114210E-04 -3.472600E-07
23 0.000000E+00 1.064380E-04 -6.081970E-07
Face No. A8 A10 A12
3 6.523040E-09 -1.710120E-11 0.000000E+00
4 3.705270E-09 8.116840E-12 0.000000E+00
9 6.386030E-11 -1.687680E-12 0.000000E+00
22 1.605330E-09 1.759010E-11 0.000000E+00
23 3.508400E-09 -4.150720E-12 0.000000E+00

[Table 9]
Lens Group No. Focal length of lens group
1 -26.837
2 20.499
3 -57.450
4 -839.867

[Table 10]
Overall length Wide-angle end 92.998
Telephoto end 88.871

[Example 3]
9 is a diagram showing a schematic optical configuration of the zoom lens of Example 3 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 3 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed in the second lens group G2. A cover glass CG is disposed between the fourth lens group G4 and the image surface IMG. The second lens group G2 corresponds to the intermediate group described above. The third lens group G3 corresponds to the L-1th lens group described above. The fourth lens group G4 corresponds to the Lth lens group described above.

The zoom lens of Example 3 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 3, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, and the fourth lens group G4 gradually moves toward the object side relative to the image surface.

Table 11 is a table of surface data for the zoom lens of Example 3. In Table 11, No. 1 to 8 are surface numbers of the first lens group G1. No. 9 to 17 are surface numbers of the second lens group G2, and No. 12 represents the aperture. No. 18 and 19 are surface numbers of the third lens group G3, and No. 20 to 23 are surface numbers of the fourth lens group G4. No. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

[Table 11]
Surface No. rd Nd vd
1 40.135 1.800 1.6859 50.34
2 15.385 3.420
3＊ 135.467 1.700 1.7041 48.38
4* 41.176 8.377
5 -65.436 1.000 1.4970 81.61
6 37.79 0.100
7 25.42 5.410 1.6360 34.81
8 227.684 d8
9＊ 45.145 0.800 1.6730 38.15
10 12.841 6.039 1.6177 49.82
11 -150.093 2.729
12S INF 2.139
13 52.871 6.176 1.5307 60.75
14 -20.775 0.150
15 20.516 0.800 1.7475 37.36
16 10.576 5.211 1.4970 81.61
17 94.307 d17
18 35.614 0.700 1.5082 68.23
19 15.467 d19
20 -484.514 3.339 1.5939 39.45
21 -24.163 0.304
22＊ -18.605 0.848 1.6889 31.16
23* -77.805 d23
24 INF 2.500 1.5168 64.20
25 INF 1.000
26 INF

Table 12 shows the specifications of the zoom lens of Example 3. Table 13 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 3. Table 14 shows the focal length of each lens group constituting the zoom lens of Example 3. Table 15 shows the overall length of the zoom lens of Example 3 at the wide-angle end and the telephoto end when focused on infinity.

[Table 12]
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.4430 21.9163 27.3686 16.8202 20.8403 25.5551
Fno 2.8907 2.8890 2.8862 1.8590 2.3454 2.9427
ω 52.1817 44.6904 37.7382 51.5900 43.9703 36.9687
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 15.0789 7.5064 1.6452 15.0789 7.5064 1.6452
d17 0.6112 0.3747 0.3019 1.7450 1.8468 2.1801
d19 5.6869 8.2370 9.5524 4.5531 6.7649 7.6741
d23 16.2467 17.9173 21.6085 16.2467 17.9173 21.6085

[Table 13]
Surface No. k A4 A6
3 2.000000E+00 2.346800E-04 -1.283280E-06
4 2.299290E+00 2.480280E-04 -1.062380E-06
9 0.000000E+00 -3.109300E-05 -9.536710E-08
22 0.000000E+00 8.522510E-05 -5.489420E-07
23 0.000000E+00 9.110860E-05 -7.083750E-07
Face No. A8 A10 A12
3 6.772940E-09 -1.783840E-11 2.283770E-14
4 3.536510E-09 1.150540E-11 -6.926320E-14
9 -1.544700E-10 -1.649420E-12 0.000000E+00
22 2.578730E-09 2.971930E-12 0.000000E+00
23 3.960510E-09 -8.641560E-12 0.000000E+00

[Table 14]
Lens Group No. Focal length of lens group
1 -26.637
2 19.481
3 -54.435
4 -218.763

[Table 15]
Overall length Wide-angle end 92.165
Telephoto end 87.649

[Example 4]
13 is a diagram showing a schematic optical configuration of the zoom lens of Example 4 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 4 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed in the second lens group G2. A cover glass CG is disposed between the fourth lens group G4 and the image surface IMG. The second lens group G2 corresponds to the intermediate group described above. The third lens group G3 corresponds to the L-1th lens group described above. The fourth lens group G4 corresponds to the Lth lens group described above.

The zoom lens of Example 4 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 4, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, and the fourth lens group G4 gradually moves toward the object side relative to the image surface.

Table 16 is a table of surface data for the zoom lens of Example 4. In Table 16, No. 1 to 8 are surface numbers of the first lens group G1. No. 9 to 17 are surface numbers of the second lens group G2, and No. 12 represents the aperture. No. 18 and 19 are surface numbers of the third lens group G3, and No. 20 to 23 are surface numbers of the fourth lens group G4. No. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

[Table 16]
Surface No. rd Nd vd
1 40.135 1.800 1.7292 54.67
2 15.385 3.420
3＊ 133.835 1.700 1.6935 53.19
4* 43.727 7.736
5 -71.205 1.000 1.4970 81.61
6 49.654 0.100
7 26.796 5.410 1.6200 36.26
8 94.21 d8
9＊ 38.499 0.800 1.6730 38.15
10 12.284 5.128 1.6177 49.82
11 -1824.113 1.010
12S INF 5.807
13 45.734 5.888 1.5378 74.70
14 -21.495 0.150
15 21.536 0.800 1.8830 40.81
16 11.929 5.609 1.4970 81.61
17 -417.619 d17
18 2334.779 0.700 1.4875 70.24
19 22.666 d19
20 390.373 3.373 1.5337 51.03
21 -28.874 5.209
22＊ -15.663 0.700 1.6889 31.16
23* -38.528 d23
24 INF 2.500 1.5168 64.20
25 INF 1.000
26 INF

Table 17 shows the specifications of the zoom lens of Example 4. Table 18 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 4. Table 19 shows the focal length of each lens group constituting the zoom lens of Example 4. Table 20 shows the overall length of the zoom lens of Example 4 at the wide-angle end and the telephoto end when focused on infinity.

[Table 17]
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.4475 21.7901 27.3762 16.8382 20.8080 25.4483
Fno 2.8914 2.8724 2.8870 1.8585 2.3401 2.9317
ω 52.4766 44.9376 37.9610 52.2882 44.6970 37.6171
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 15.5255 7.4826 1.4155 15.5255 7.4826 1.4155
d17 0.4292 1.0755 1.3366 1.3409 2.2128 3.0392
d19 4.2615 6.0518 7.7997 3.3499 4.9145 6.0972
d23 13.9450 15.3578 18.0461 13.9450 15.3578 18.0461

[Table 18]
Surface No. k A4 A6
3 5.604820E-01 2.290800E-04 -1.298570E-06
4 5.944550E-01 2.341960E-04 -1.093910E-06
9 0.000000E+00 -3.121020E-05 -6.469510E-08
22 0.000000E+00 9.369350E-05 -5.397950E-07
23 0.000000E+00 9.041790E-05 -6.703890E-07
Face No. A8 A10 A12
3 6.818720E-09 -1.741560E-11 2.327870E-14
4 3.397020E-09 1.118960E-11 -6.283920E-14
9 -2.732030E-10 -1.273970E-13 0.000000E+00
22 3.243850E-09 -3.929790E-13 0.000000E+00
23 3.677590E-09 -7.160300E-12 0.000000E+00

[Table 19]
Lens Group No. Focal length of lens group
1 -26.527
2 20.141
3 -46.957
4 -499.998

[Table 20]
Overall length Wide-angle end 94.000
Telephoto end: 88.4368

[Example 5]
17 is a diagram showing the optical configuration of the zoom lens of Example 5 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 5 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a fourth lens group G4 having a negative refractive power. The aperture stop S is disposed in the second lens group G2. A cover glass CG is disposed between the fourth lens group G4 and the image surface IMG. The second lens group G2 corresponds to the intermediate group described above. The third lens group G3 corresponds to the L-1th lens group described above. The fourth lens group G4 corresponds to the Lth lens group described above.

The zoom lens of Example 5 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 5, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, and the fourth lens group G4 gradually moves toward the object side relative to the image surface.

Table 21 is a table of surface data for the zoom lens of Example 5. In Table 21, No. 1 to 8 are surface numbers of the first lens group G1. No. 9 to 17 are surface numbers of the second lens group G2, and No. 12 represents the aperture. No. 18 and 19 are surface numbers of the third lens group G3, and No. 20 to 23 are surface numbers of the fourth lens group G4. No. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

Table 21.
Surface No. rd Nd vd
1 40.135 1.800 1.6273 58.97
2 15.385 3.420
3＊ 114.227 1.700 1.7492 34.61
4* 29.429 8.116
5 -60.713 1.000 1.6204 60.32
6 56.034 0.100
7 28.535 5.410 1.7552 27.58
8 140.587 d8
9＊ 68.077 0.800 1.7468 38.71
10 13.232 6.257 1.6690 52.41
11 -67.649 0.850
12S INF 4.043
13 28.052 6.249 1.5136 67.72
14 -29.573 0.150
15 26.516 0.800 1.7443 44.05
16 10.836 7.381 1.4875 70.41
17 -41.455 d17
18 25.822 0.700 1.4939 66.64
19 12.510 d19
20 -293.329 5.016 1.4875 70.41
21 -11.983 0.053
22＊ -10.719 0.700 1.7440 44.85
23* -49.061 d23
24 INF 2.500 1.5168 64.20
25 INF 1.032
26 INF

Table 22 shows the specifications of the zoom lens of Example 5. Table 23 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 5. Table 24 shows the focal length of each lens group constituting the zoom lens of Example 5. Table 25 shows the overall length of the zoom lens of Example 5 at the wide-angle end and the telephoto end when focused on infinity.

Table 22.
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.4509 21.9158 27.3621 16.7484 20.6664 25.1244
Fno 2.8920 2.8890 2.8855 1.8504 2.3272 2.9101
ω 52.5956 44.9344 37.5309 52.3085 44.6090 37.1522
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 14.6670 7.5836 1.2000 14.6670 7.5836 1.2000
d17 0.2794 0.8994 2.1965 1.1171 2.0320 3.7958
d19 4.8927 5.5413 6.5344 4.0550 4.4087 4.9352
d23 16.1164 18.3060 19.1642 16.1164 18.3060 19.1642

[Table 23]
Surface No. k A4 A6
3 5.939060E-01 2.223960E-04 -1.273780E-06
4 6.058330E-01 2.527260E-04 -9.944040E-07
9 0.000000E+00 -2.161960E-05 -6.077540E-08
22 0.000000E+00 1.211380E-04 1.043970E-07
23 0.000000E+00 8.991450E-05 -6.454230E-07
Face No. A8 A10 A12
3 6.624810E-09 -1.773010E-11 2.225730E-14
4 3.117650E-09 1.881210E-11 -8.538410E-14
9 1.545970E-10 9.688290E-14 0.000000E+00
22 -4.769900E-09 8.266010E-11 0.000000E+00
23 3.710020E-09 -1.209950E-11 0.000000E+00

Table 24.
Lens Group No. Focal length of lens group
1 -22.033
2 18.296
3 -50.000
4 -66.667

Table 25.
Overall length Wide-angle end 94.032
Telephoto end: 87.1718

[Example 6]
21 is a diagram showing a schematic optical configuration of the zoom lens of Example 6 at the wide-angle end and the telephoto end when focusing on infinity. The zoom lens of Example 6 is composed of, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a negative refractive power. A diaphragm S is disposed between the second lens group G2 and the third lens group G3. A cover glass CG is disposed between the fifth lens group G5 and the image surface IMG. The second lens group G2 and the third lens group G3 correspond to the intermediate group described above. The fourth lens group G4 corresponds to the L-1th lens group described above. The fifth lens group G5 corresponds to the Lth lens group described above.

The zoom lens of Example 6 performs a magnification change operation by changing the air gap between each lens group. In the zoom lens of Example 6, when changing magnification from the wide-angle end to the telephoto end, the first lens group G1 gradually moves toward the image side, the second lens group G2 gradually moves toward the object side, the third lens group G3 gradually moves toward the object side, the fourth lens group G4 gradually moves toward the object side, and the fifth lens group G5 gradually moves toward the object side relative to the image surface.

Table 26 is a table of surface data for the zoom lens of Example 6. In Table 26, No. 1 to 8 are surface numbers of the first lens group G1, and No. 9 to 11 are surface numbers of the second lens group G2. No. 12 represents the aperture. No. 13 to 17 are surface numbers of the third lens group G3, and No. 18 and 19 are surface numbers of the fourth lens group G4. No. 20 to 23 are surface numbers of the fifth lens group G5. No. 24 and 25 represent the cover glass CG, and No. 26 represents the image surface.

[Table 26]
Surface No. rd Nd vd
1 40.740 1.800 1.7216 46.72
2 15.529 3.422
3＊ 98.061 1.700 1.6713 51.58
4* 31.031 8.354
5 -40.249 1.000 1.5065 68.40
6 45.549 0.239
7 29.224 5.410 1.7463 28.57
8 430.227 d8
9＊ 28.875 0.800 1.6978 34.77
10 13.397 7.359 1.5729 60.67
11 -133.187 d11
12S INF 3.059
13 23.792 5.307 1.5394 65.49
14 -50.964 0.150
15 19.141 0.800 1.7443 43.93
16 9.357 6.228 1.4875 70.41
17 301.579 d17
18 31.959 0.700 1.5275 56.27
19 14.341 d19
20 -50.893 4.221 1.4875 70.41
21 -17.520 0.273
22＊ -13.327 0.700 1.7470 38.25
23* -24.770 d23
24 INF 2.500 1.5168 64.20
25 INF 1.000
26 INF

Table 27 shows the specifications of the zoom lens of Example 6. Table 28 shows the aspheric coefficients of each aspheric surface in the zoom lens of Example 6. Table 29 shows the focal length of each lens group constituting the zoom lens of Example 6. Table 30 shows the overall length of the zoom lens of Example 6 at the wide-angle end and the telephoto end when focused on infinity.

[Table 27]
Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end
f 17.4333 21.9074 27.4511 16.7687 20.7817 25.5325
Fno 2.8891 2.8879 2.8949 1.8555 2.3399 2.9433
ω 52.4960 44.6800 37.4573 51.9607 44.0975 36.8605
Y 21.6330 21.6330 21.6330 21.6330 21.6330 21.6330
Object distance INF INF INF 177.00 180.00 184.34
d8 13.2879 6.7037 1.2442 13.2879 6.7037 1.2442
d11 5.6172 4.9717 4.1574 5.6172 4.9717 4.1574
d17 0.2995 0.3028 0.8219 1.3537 1.6324 2.5416
d19 4.2651 5.1908 5.4359 3.2109 3.8613 3.7163
d23 15.5093 18.9493 23.0015 15.5093 18.9493 23.0015

Table 28:
Surface No. k A4 A6
3 2.000000E+00 2.120480E-04 -1.230530E-06
4 4.680980E-01 2.311150E-04 -1.005800E-06
9 0.000000E+00 -8.334680E-06 -8.627420E-09
22 0.000000E+00 1.224220E-04 -1.301110E-07
23 0.000000E+00 1.179730E-04 -4.255520E-07
Face No. A8 A10 A12
3 6.585590E-09 -1.824180E-11 2.464170E-14
4 3.594070E-09 9.753850E-12 -5.229250E-14
9 6.604890E-11 2.740320E-13 0.000000E+00
22 3.759400E-09 2.002540E-11 0.000000E+00
23 4.464380E-09 -1.287380E-11 0.000000E+00

Table 29.
Lens Group No. Focal length of lens group
1 -23.060
2 52.915
3 23.453
4 -50.000
5 -142.857

[Table 30]
Overall length Wide-angle end 94.000
Telephoto end 89.682

The values calculated using the above formulas in Examples 1 to 6 and the numerical values used in the formulas are shown in Table 31.

Table 31.
Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Formula (1) -0.996 -0.981 -0.973 -0.969 -0.805 -0.840
Formula (2) 1.521 1.458 1.471 1.701 1.451 1.447
Equation (3) -1.840 -2.099 -1.989 -1.715 -1.827 -1.821
Formula (4) 0.786 0.806 0.806 0.807 0.807 0.806
Equation (5) 0.939 1.001 0.864 0.890 0.840 0.762
Formula (6) 1.620 1.620 1.636 1.620 1.755 1.746
Equation (7) 0.622 0.606 0.624 0.633 0.531 -129.999
Formula (8) 0.506 0.307 0.349 0.285 0.239 0.198
Equation (9) 0.664 0.352 0.326 0.244 0.280 0.245
Formula (10) 0.096 0.128 0.060 0.052 0.044 0.045
Formula (11) 4.30 4.30 4.26 4.35 4.35 4.35
Formula (12) 1.5831 1.5687 1.5690 1.5691 1.5679 1.5746
Formula (13) 0.248 0.068 0.249 0.094 0.750 0.350
fw 17.003 17.444 17.443 17.448 17.451 17.433
ft 26.917 27.364 27.369 27.376 27.362 27.451
f1 -26.813 -26.837 -26.637 -26.527 -22.033 -23.060
βL-1w 1.521 1.458 1.471 1.701 1.451 1.447
fL-1 -49.519 -57.450 -54.435 -46.957 -50.000 -50.000
Yimw 21.633 21.633 21.633 21.633 21.633 21.633
NdLP1 1.620 1.620 1.636 1.620 1.755 1.746
f12w 10.578 10.578 10.891 11.049 9.262 -2266.317
DLt 13.607 8.407 9.552 7.800 6.534 5.436
DLw 11.297 6.146 5.687 4.262 4.893 4.265
Dg1pw 15.959 17.470 15.079 15.526 14.667 13.288
Dg1pt 2.578 3.500 1.645 1.416 1.200 1.244

1. Mirrorless single-lens camera (imaging device)
2 Main body 3 Lens barrel 21 CCD sensor (imaging element)
22 cover glass 30 zoom lens 31 first lens group 32 second lens group (middle group)
33 third lens group (L-1 lens group)
34 4th lens group (Lth lens group)
G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group 35 Aperture CG Cover glass OA Optical axis S Aperture

Claims (14)

The optical system is composed of L lens groups, where L is an integer equal to or greater than 4,
The zoom lens includes, in order from the object side, a first lens group having negative refractive power, an intermediate group having one or more lens groups and having a composite positive refractive power, an L-1 lens group having negative refractive power, and an L lens group having negative refractive power, and performs a magnification change operation by changing the interval between adjacent lens groups.
the first lens group moves toward the image side when changing magnification from a wide-angle end to a telephoto end,
A zoom lens that satisfies the following formula:
-1.200<f ₁ /f _t <-0.804 (1)
1.10<β _L-1w <2.00 (2)
L _max /Y _imw <4.6...(11')
however,
f ₁ : focal length of the first lens group f _t : focal length of the zoom lens at the telephoto end when focusing on infinity β _L-1w : lateral magnification of the L-1 lens group at the wide-angle end L _max : maximum overall length in the entire zoom range (distance from the object-side lens surface of the lens closest to the object to the image plane)
Y _imw : Maximum image height at the wide-angle end of the zoom lens when focused at infinity The optical system is composed of L lens groups, where L is an integer equal to or greater than 4,
The zoom lens includes, in order from the object side, a first lens group having negative refractive power, an intermediate group having one or more lens groups and having a composite positive refractive power, an L-1 lens group having negative refractive power, and an L lens group having negative refractive power, and performs a magnification change operation by changing the interval between adjacent lens groups.
the first lens group includes at least one lens having a positive refractive power;
A zoom lens that satisfies the following formula:
-1.200<f ₁ /f _t <-0.804 (1)
1.41<β _L-1w ≦1.701...(2')
1.58<N _dLP1 <1.90...(6')
however,
f ₁ : focal length of the first lens group f _t : focal length of the zoom lens at the telephoto end when focused on infinity β _L-1w : lateral magnification of the L-1 lens group at the wide-angle end
N _dLP1 : the refractive index at the d line of the lens having the positive refractive power The optical system is composed of L lens groups, where L is an integer equal to or greater than 4,
The zoom lens includes, in order from the object side, a first lens group having negative refractive power, an intermediate group having one or more lens groups and having a composite positive refractive power, an L-1 lens group having negative refractive power, and an L lens group having negative refractive power, and performs a magnification change operation by changing the interval between adjacent lens groups.
the first lens group is composed of a total of four lenses including three lenses having negative refractive power and one lens having positive refractive power,
A zoom lens that satisfies the following formula:
-1.200<f ₁ /f _t <-0.804 (1)
1.10<β _L-1w <2.00 (2)
L _max / Y _imw <5...(11)
however,
f ₁ : focal length of the first lens group f _t : focal length of the zoom lens at the telephoto end when focusing on infinity β _L-1w : lateral magnification of the L-1 lens group at the wide-angle end L _max : maximum overall length in the entire zoom range (distance from the object-side lens surface of the lens closest to the object to the image plane)
Y _imw : Maximum image height at the wide-angle end of the zoom lens when focused at infinity The zoom lens according to claim 2 or 3, wherein the first lens group moves toward the image side when changing magnification from the wide-angle end to the telephoto end. the first lens group includes at least one lens having a positive refractive power,
4. The zoom lens according to claim 1 , which satisfies the following formula:
1.58<N _dLP1 <2.20 (6)
however,
N _dLP1 : the refractive index at the d line of the lens having the positive refractive power 6. The zoom lens according to claim 1 , which satisfies the following formula:
-8.4<f _L-1 /f _t <-0.7 (3)
however,
f _L-1 : focal length of the L-1 lens group 7. The zoom lens according to claim 1 , which satisfies the following formula:
0.5<f _w /Y _imw <5.0 (4)
however,
_Yimw : maximum image height at the wide-angle end of the zoom lens when focused on infinity _fw : focal length at the wide-angle end of the zoom lens when focused on infinity 8. The zoom lens according to claim 1 , which satisfies the following formula:
0.6<D _g1pw /f _w <1.3 (5)
however,
D _g1pw : The distance on the optical axis between the lens surface in the first lens group closest to the image side and the lens surface in the intermediate group closest to the object side at the wide-angle end when the zoom lens is focused on infinity. f _w : The focal length of the zoom lens at the wide-angle end when the zoom lens is focused on infinity. The zoom lens according to any one of claims 1 to 8, in which all of the groups from the intermediate group to the L lens group move toward the object side when changing magnification from the wide-angle end to the telephoto end. the intermediate group has a second lens group closest to the object side,
10. The zoom lens according to claim 1, which satisfies the following formula:
0.10<f _12w /f _w <0.80 (7)
however,
_f12w : a composite focal length of the first lens group and the second lens group at the wide-angle end when the zoom lens is focused on infinity; _fw : a focal length of the zoom lens at the wide-angle end when the zoom lens is focused on infinity; 11. The zoom lens according to claim 1, which satisfies the following formula:
0.001<D _Lt /f _t <0.770 (8)
however,
D _Lt : the distance on the optical axis between the lens surface closest to the object in the L lens group and the lens surface closest to the image in the L-1 lens group at the telephoto end when the zoom lens is focused on infinity 12. The zoom lens according to claim 1, which satisfies the following formula:
0.001< _DLw / _fw <0.900...(9)
however,
D _Lw : The distance on the optical axis between the lens surface closest to the object in the L lens group and the lens surface closest to the image in the L-1 lens group at the wide-angle end when the zoom lens is focused on infinity. f _w : The focal length of the zoom lens at the wide-angle end when the zoom lens is focused on infinity. 13. The zoom lens according to claim 1, which satisfies the following formula:
0.03<D _g1pt / _ft <0.20 (10)
however,
D _g1pt : the distance on the optical axis between the lens surface in the first lens group closest to the image side and the lens surface in the intermediate lens group closest to the object side at the telephoto end when the zoom lens is focused at infinity An imaging device comprising the zoom lens according to any one of claims 1 to 13, and an image sensor provided on the image side of the zoom lens for converting an optical image formed by the zoom lens into an electrical signal.

Images