Zoom lens and camera device

Abstract

The problem is to provide a zoom lens and imaging device that have high magnification, can shorten the minimum shooting distance, and exhibit high optical performance. The solution is to provide a zoom lens that consists, from the object side, of a first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, and a rear lens group having positive refractive power overall. This zoom lens exhibits specific optical characteristics expressed by two equations.

Description

Technical Field

[0001] The present invention relates to a zoom lens and an imaging device. Background Art

[0002] Among conventional zoom lenses (zoom lenses), those used in mirrorless single-lens cameras, digital cameras, security cameras, and the like are known as high-magnification zoom lenses.

[0003] As for this zoom lens, for example, a zoom lens system is known in which the signs of the refractive powers of the lens groups in order from the object side are positive, negative, positive, positive, and positive (for example, see Patent Document 1).

[0004] Furthermore, imaging lenses (imaging lenses) are known in which the signs of the refractive powers of the lens groups in order from the object side are positive-negative-positive-positive or positive-negative-positive-negative (see, for example, Patent Document 2).

[0005] Furthermore, a zoom lens is known in which the signs of the refractive powers of the lens units in order from the object side are positive-negative-positive and negative-positive (for example, see Patent Document 3).

[0006] Prior art literature

[0007] Patent Literature

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-176229

[0009] [Patent Document 2] International Publication No. 2013-151153

[0010] [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-195749 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] As the number of pixels in solid-state imaging devices used in cameras has continued to increase in recent years, zoom lenses are required to achieve even higher performance than before. In particular, high-magnification zoom lenses are required to offer high performance for multi-purpose use.

[0013] The zoom lens system described in Patent Document 1 has a low zoom ratio, and as the zoom ratio increases, it becomes difficult to maintain clearance between the lens groups. This makes it difficult to shoot at the shortest shooting distance and to achieve high optical performance at this time.

[0014] In the imaging lens described in Patent Document 2, the movement amount of the second lens group increases due to the small zoom ratio of the second lens group. Accordingly, the movement range of the focus group decreases, making it difficult to shoot at the shortest shooting distance and maintain the performance at that time.

[0015] The zoom lens described in Patent Document 3 has a small zoom ratio based on the second lens group, so in order to achieve a high magnification of the zoom lens, the third lens group is also moved, but the moving area of ​​the focusing group becomes smaller accordingly, making it difficult to shoot at the shortest shooting distance and maintain the performance at this time.

[0016] As described above, as zoom lenses have higher magnifications, it has become difficult to shorten the shortest photographic distance and perform aberration correction to maintain performance.

[0017] One embodiment of the present invention has been made in view of the above-mentioned problems, and provides a zoom lens and an imaging device that have a high magnification, can shorten the shortest photographing distance, and have high optical performance.

[0018] Means for solving problems

[0019] In order to solve the above-mentioned problems, a zoom lens (zoom lens) involved in one embodiment of the present invention is composed of, from the object side, a first lens group with positive optical power, a second lens group with negative optical power, and a rear group with positive optical power as a whole. The zoom action is performed by changing the interval between adjacent lens groups. The rear group includes, from the object side, at least a third lens group, a fourth lens group, and a fifth lens group. One of the lens groups among the third lens group, the fourth lens group, and the fifth lens group is a focusing group that is moved on the optical axis to perform focusing. The zoom lens satisfies the following formula:

[0020] 0.3≤|f f | / M<0.8·····(1)

[0021] 1.5≤β FW / β FT <7.0·····(2)

[0022] in,

[0023] M:f w With f t The square root of the product

[0024] f f : Focal length of the focusing group

[0025] f w : The focal length of the zoom lens at the wide-angle end when focusing at infinity

[0026] f t : The focal length of the zoom lens at the telephoto end when focusing at infinity

[0027] β FW : The horizontal magnification of the focusing group at the wide-angle end

[0028] β FT: The horizontal magnification of the focusing group at the telephoto end.

[0029] Furthermore, to solve the above-mentioned problems, an imaging device according to one embodiment of the present invention includes the zoom lens and an imaging element provided on the image side of the zoom lens and converting an optical image formed by the zoom lens into an electrical signal.

[0030] Effects of the Invention

[0031] According to one embodiment of the present invention, it is possible to provide a zoom lens and an imaging device that have a high magnification, can shorten the shortest photographing distance, and have high optical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 These are diagrams schematically showing the optical structure of the zoom lens of Example 1 when focusing at infinity at the wide-angle limit and the telephoto limit.

[0033] Figure 2 These are diagrams showing longitudinal aberrations of the zoom lens of Example 1 when focusing at infinity at the wide-angle limit.

[0034] Figure 3 Graphs showing longitudinal aberrations of the zoom lens of Example 1 when focusing at infinity at an intermediate focal length.

[0035] Figure 4 These are diagrams showing longitudinal aberrations of the zoom lens of Example 1 when focusing at infinity at the telephoto limit.

[0036] Figure 5 These are diagrams schematically showing the optical structure of the zoom lens of Example 2 when focusing at infinity at the wide-angle limit and the telephoto limit.

[0037] Figure 6 These are diagrams showing longitudinal aberrations of the zoom lens of Example 2 when focusing at infinity at the wide-angle limit.

[0038] Figure 7 Graphs showing longitudinal aberrations of the zoom lens of Example 2 when focusing at infinity at an intermediate focal length.

[0039] Figure 8 These are diagrams showing longitudinal aberrations of the zoom lens of Example 2 when focusing at infinity at the telephoto limit.

[0040] Figure 9 These are diagrams schematically showing the optical structure of the zoom lens of Example 3 when focusing at infinity at the wide-angle limit and the telephoto limit.

[0041] Figure 10 These are diagrams showing longitudinal aberrations of the zoom lens of Example 3 when focusing at infinity at the wide-angle limit.

[0042] Figure 11 Graphs showing longitudinal aberrations of the zoom lens of Example 3 when focusing at infinity at an intermediate focal length.

[0043] Figure 12 These are diagrams showing longitudinal aberrations of the zoom lens of Example 3 when focusing at infinity at the telephoto limit.

[0044] Figure 13 These are diagrams schematically showing the optical structure of the zoom lens of Example 4 when focusing at infinity at the wide-angle limit and the telephoto limit.

[0045] Figure 14 These are diagrams showing longitudinal aberrations of the zoom lens of Example 4 when focusing at infinity at the wide-angle limit.

[0046] Figure 15 Graphs showing longitudinal aberrations of the zoom lens of Example 4 when focusing at infinity at an intermediate focal length.

[0047] Figure 16 These are diagrams showing longitudinal aberrations of the zoom lens of Example 4 when focusing at infinity at the telephoto limit.

[0048] Figure 17 These are diagrams schematically showing the optical structure of the zoom lens of Example 5 when focusing at infinity at the wide-angle limit and the telephoto limit.

[0049] Figure 18 These are diagrams showing longitudinal aberrations of the zoom lens of Example 5 when focusing at infinity at the wide-angle limit.

[0050] Figure 19 Graphs showing longitudinal aberrations of the zoom lens of Example 5 when focusing at infinity at an intermediate focal length.

[0051] Figure 20 These are diagrams showing longitudinal aberrations of the zoom lens of Example 5 when focusing at infinity at the telephoto limit.

[0052] Figure 21 This is a diagram schematically showing an example of the configuration of an imaging device according to an embodiment of the present invention.

[0053] Description of reference numerals:

[0054] 1 Mirrorless single-lens camera

[0055] 2 Main body

[0056] 3 Lens barrel

[0057] 21 CCD sensor

[0058] 22. CG protective glass

[0059] 30 zoom lens

[0060] 31. G1 Lens Group 1

[0061] 32, G2 Second lens group

[0062] 33. G3: The third lens group

[0063] 34, G4: The 4th lens group

[0064] 35, G5 5th lens group

[0065] 36. S-stop

[0066] G6 6th lens group

[0067] G7 7th lens group

[0068] OA optical axis. DETAILED DESCRIPTION

[0069] The following describes an embodiment of a zoom lens and an imaging device according to one embodiment of the present invention. More specifically, this embodiment relates to a zoom lens (zoom lens) suitable for use in photographic optical systems of digital input / output devices such as mirrorless single-lens cameras, security cameras, digital cameras, and medical cameras that utilize solid-state imaging elements. The zoom lens and imaging device described below represent one embodiment 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 embodiment.

[0070] 1. Zoom lens

[0071] 1-1. Optical structure

[0072] The zoom lens according to one embodiment of the present invention is composed of, in order from the object side, a first lens group having positive optical focal length, a second lens group having negative optical focal length, and a rear lens group having positive optical focal length. The rear lens group includes, in order from the object side, at least a third lens group, a fourth lens group, and a fifth lens group. One of the third lens group, the fourth lens group, and the fifth lens group is a focusing group. The zoom lens performs a zooming operation by changing the intervals between adjacent lens groups. The zoom lens achieves a high magnification by appropriately configuring the lens configuration and optical focal length of the optical system, can shorten the minimum photographic distance, and has high optical performance.

[0073] In this specification, "shortening the shortest photographic distance" means shortening the distance that can be photographed from the lens surface of the lens disposed closest to the object to the object in close-range photography. The "shortest photographic distance" can also be referred to as the shortest focusing distance.

[0074] In addition, in this specification, "lens group" means a collection of more than one lenses that are linked together in a zooming action. A lens group can be composed of one lens or a plurality of lenses. For example, a lens group can include a cemented lens in which a plurality of single lenses are integrated without an air gap, or a composite lens in which a single lens and a resin are integrated without an air gap. The lenses in the lens group move while maintaining a relative positional relationship during the zooming action. The zooming action is performed by changing the intervals between the lens groups, and the intervals between lenses belonging to the same lens group do not change during the zooming action.

[0075] In this specification, a "lens" refers not only to a single lens but also to a cemented lens or a compound lens. For example, a cemented lens formed by cementing two single lenses together is described as a single lens. Furthermore, a compound lens formed by combining a single lens with a resin is described as a single lens.

[0076] (1) Lens Group 1

[0077] The first lens group is the lens group positioned closest to the object side of the zoom lens and has positive refractive power. The first lens group only needs to have positive refractive power as a whole, and it only needs to include at least one lens with positive refractive power. The lens structure of the first lens group can be appropriately determined within a range that allows for positive refractive power as a whole.

[0078] (2) Second lens group

[0079] The second lens group is positioned on the image side of the first lens group and has negative refractive power. The second lens group need only have negative refractive power as a whole, and it only needs to include at least one lens with negative refractive power. The lens structure of the second lens group can be appropriately determined within a range where the entire lens group has negative refractive power.

[0080] (3) Rear group

[0081] The rear group is a collection of lens groups arranged on the image side of the second lens group, and the rear group as a whole has positive optical power. The rear group includes, in order from the object side, at least the third lens group, the fourth lens group, and the fifth lens group. The third lens group is arranged adjacent to the fourth lens group, and the fourth lens group is arranged adjacent to the fifth lens group. The rear group may also include one or more lens groups on the image side of the fifth lens group. For example, the rear group may include the sixth lens group on the image side of the fifth lens group, or the sixth and seventh lens groups may be arranged in order from the object side on the image side of the fifth lens group.

[0082] The rear group only needs to have positive optical power as a whole and only needs to include at least one lens group with positive optical power. The rear group can also be composed of only one or more lens groups with positive optical power. Furthermore, the rear group only needs to have positive optical power as a whole and may also include lens groups with negative optical power. Preferably, it includes at least one lens group with positive optical power and at least one lens group with negative optical power.

[0083] The zoom lens with high magnification is preferably changed by mainly moving the second lens group with strong optical focal length. Therefore, from the perspective of properly correcting the aberration changes, especially the spherical aberration changes, caused by the zooming of the second lens group, it is preferred to arrange the third lens group with positive optical focal length on the image side of the second lens group. In the case where the third lens group with negative optical focal length is arranged on the image side of the second lens group, it is sometimes impossible to properly correct the aberration correction caused by the zooming of the second lens group. For this reason, it is preferred to arrange a lens group with positive optical focal length further to the image side than the third lens group with negative optical focal length, so it is sometimes difficult to shorten the total length of the zoom lens. Therefore, from the perspective of realizing a zoom lens with high magnification, it is preferred that the third lens group has positive optical focal length.

[0084] From the perspective of being able to offset aberrations occurring in each lens group, it is preferable to alternately arrange lens groups with positive and negative power in the rear lens group. Therefore, since it is preferable for the third lens group to have positive power as described above, it is preferable for the fourth lens group to have negative power and for the fifth lens group to have positive power.

[0085] (4) Focusing group

[0086] The zoom lens has a focusing group. The focusing group performs focusing by moving on the optical axis of the zoom lens. In this zoom lens, the focusing group can also be used for focusing. In this case, the focusing group can be moved in the direction of the optical axis. The focusing group is one of the third lens group, the fourth lens group, and the fifth lens group. From the perspective of suppressing the aberration variation associated with focusing, it is preferably one of the fourth lens group and the fifth lens group. In addition, from the perspective of reducing the maximum movement of the lens group with positive optical focal length that occupies a large distance on the optical axis and realizing a compact zoom lens with a high magnification, it is preferred that the focusing group has negative optical focal length, and the trajectory of movement from the wide-angle end to the telephoto end is set to a U-shaped turn trajectory convex to the image side.

[0087] The third lens group is generally very effective against spherical aberration, but less so against curvature of field. Therefore, if the third lens group is used as a focusing group, while on-axis focus is easy to achieve, peripheral resolution is likely to be insufficient. On the other hand, the fourth and fifth lens groups are generally equally effective against both spherical aberration and curvature of field. Therefore, to achieve adequate resolution both on-axis and peripherally, it is preferable to use either the fourth or fifth lens group as a focusing group.

[0088] (5) Aperture

[0089] The zoom lens may also have an aperture. Here, the aperture is an aperture that defines the beam diameter of the zoom lens, that is, the aperture that defines the F value of the zoom lens. The arrangement of the aperture in the zoom lens is not limited.

[0090] (6) Lens group structure

[0091] This zoom lens consists, in order from the object side, of a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear lens group having positive refractive power. The rear lens group includes, in order from the object side, at least a third lens group, a fourth lens group, and a fifth lens group. No other lens groups are included between the first and second lens groups, between the second and third lens groups, between the third and fourth lens groups, and between the fourth and fifth lens groups. However, optical elements other than lenses, such as filters and apertures, are not excluded.

[0092] 1-2. Action

[0093] (1) Actions during zooming

[0094] In this zoom lens, when the zoom is changed from the wide-angle end to the telephoto end, at least the air space between the lens groups is changed. In addition, when the zoom is changed from the wide-angle end to the telephoto end, from the viewpoint of reducing the amount of movement of the second lens group during the zoom and reducing the aberration variation caused by the zoom of the second lens group, it is preferred that at least two lens groups in the rear group move on the optical axis when the zoom is changed from the wide-angle end to the telephoto end. This is suitable for achieving a zoom lens that is high in magnification, compact, and has high optical performance. In addition, from the viewpoint of being able to effectively utilize limited space and achieve a high magnification zoom lens, it is preferred that at least one of the at least two lens groups that move in the rear group has a trajectory that makes a U-shaped turn at one point from the wide-angle end to the telephoto end.

[0095] Furthermore, to achieve higher performance, the rear moving lens group preferably includes at least one lens group with positive power and at least one lens group with negative power. By moving the positive and negative lens groups as a pair in the rear lens group, aberrations generated in the two lens groups can be offset, further suppressing spherical aberration and field curvature for the zoom lens as a whole. Therefore, this is preferable from the perspective of achieving higher performance.

[0096] Furthermore, when zooming from the wide-angle end to the telephoto end, it is preferable to have the third lens group fixed in order to achieve a zoom lens with high optical performance while ensuring a stable range of movement for the focus group, shortening the minimum shooting distance. Furthermore, the third lens group is generally very effective in combating spherical aberration. A fixed third lens group is advantageous in terms of facilitating adjustment of the optical characteristics within the third lens group. Therefore, it is preferable from the perspective of achieving high performance, particularly at the wide-angle end with a small F-value. A fixed third lens group means that the third lens group does not substantially move during zooming.

[0097] Furthermore, from the perspective of achieving a higher magnification, when zooming from the wide-angle end to the telephoto end, it is preferable to increase the air gap between the first lens group and the second lens group. Furthermore, from the perspective of achieving a higher magnification, it is preferable to decrease the air gap between the second lens group and the third lens group.

[0098] (2) Focusing action

[0099] In this zoom lens, focusing can be achieved using the aforementioned focusing group. As mentioned above, the focusing group that moves when focusing from infinity to a nearby object is one of the third, fourth, and fifth lens groups. The direction of movement of the focusing group during focusing is not limited.

[0100] 1-3. Formulas expressing zoom lens conditions

[0101] The zoom lens according to the present embodiment preferably has the above-described configuration and satisfies at least one of the following expressions.

[0102] 0.3≤|f f | / M<0.8·····(1)

[0103] in,

[0104] M:f w With f t The square root of the product

[0105] f f : Focal length of the focusing group

[0106] fw : The focal length of a zoom lens at the wide-angle end when focusing at infinity

[0107] f t : The focal length of a zoom lens at the telephoto end when focusing at infinity

[0108] As described above, M is the square root of the product of the focal length of the zoom lens at the wide-angle end when focusing at infinity and the focal length of the zoom lens at the telephoto end when focusing at infinity. Specifically, M is defined by the following formula.

[0109]

[0110] Formula (1) is a formula for specifying the optical focal length of the focus group. From the perspective of achieving a high magnification of the zoom lens and shortening the shooting distance in the entire zoom range, it is preferable to satisfy Formula (1). In contrast, when the formula is lower than the lower limit of Formula (1), the optical focal length of the focus group is sometimes too strong. Therefore, although it is beneficial to achieve a high magnification of the zoom lens, the aberration variation at each focus distance increases, and sometimes it is difficult to maintain optical performance when shooting at the shortest shooting distance. In addition, when the formula is higher than the upper limit of Formula (1), the optical focal length of the focus group is sometimes too weak. Therefore, although it becomes easy to suppress the aberration variation at each focus distance, the movement amount for focusing in the entire zoom range becomes larger, and sometimes it is difficult to achieve a high magnification of the zoom lens at the desired full length.

[0111] From the perspective of maintaining optical performance even when shooting at the shortest shooting distance, f | / M is more preferably 0.35 or more, and even more preferably 0.45 or more. In addition, from the perspective of achieving a higher magnification of the zoom lens, |f f | / M is more preferably 0.7 or less, and further preferably 0.6 or less.

[0112] The zoom lens according to this embodiment preferably satisfies the following formula.

[0113] 1.5≤β FW / β FT <7.0·····(2)

[0114] in,

[0115] β FW : Horizontal magnification of the focusing group at the wide-angle end

[0116] β FT : Horizontal magnification of the focusing group at the telephoto end

[0117] Formula (2) is a formula for specifying the lateral magnification of the focusing group. From the perspective of appropriately correcting the aberrations associated with the high magnification of the zoom lens, it is preferable to satisfy Formula (2). In contrast, when the value is lower than the lower limit of Formula (2), although the aberration correction during focusing in the entire zoom range becomes easy, the ratio of the multiplication based on the focusing group is sometimes too small. Therefore, it is sometimes difficult to achieve a high magnification of the zoom lens. In addition, when the value is higher than the upper limit of Formula (2), although it is beneficial to achieve a high magnification of the zoom lens, it is sometimes difficult to correct the aberrations within the focusing group. Therefore, it is sometimes difficult to appropriately correct the aberrations during focusing in the entire zoom area.

[0118] From the perspective of achieving higher magnification of zoom lenses, β FW / β FT More preferably, it is 1.8 or more, and even more preferably, it is 2.0 or more. In addition, from the perspective of appropriately correcting the aberration during focusing in the entire zoom range, β FW / β FT It is more preferably 6.0 or less, and even more preferably 5.0 or less.

[0119] The zoom lens according to this embodiment preferably satisfies the following formula.

[0120] 5.0≤β 2T / β 2W ≤40.0·····(3)

[0121] in,

[0122] β 2T : Horizontal magnification of the second lens group at the telephoto end

[0123] β 2W : Horizontal magnification of the second lens group at the wide-angle end

[0124] Formula (3) is a formula for specifying the zoom ratio based on the second lens group. From the perspective of being able to achieve a balance between the zoom ratio of the second lens group and other lens groups, achieving a high magnification of the zoom lens, and appropriately correcting aberrations, it is preferable to satisfy Formula (3). In contrast, when the value is lower than the lower limit of Formula (3), the zoom ratio obtained by moving the second lens group is sometimes too small. Therefore, due to the increase in the amount of movement of the second lens group, it is sometimes difficult to achieve a high magnification of the zoom lens at the desired full length. In addition, when the value is higher than the upper limit of Formula (3), the optical power of the second lens group becomes stronger. If the amount of movement of the second lens group is increased, it is easy to achieve a high magnification of the zoom lens, but sometimes the aberration change during magnification is too large. Therefore, it is sometimes difficult to obtain high optical performance throughout the entire zoom range.

[0125] From the perspective of properly correcting aberrations, β 2T / β 2WIt is more preferably 7.0 or more, and even more preferably 9.0 or more. In order to achieve a higher magnification of the zoom lens, β 2T / β 2W It is more preferably 30.0 or less, and even more preferably 20.0 or less.

[0126] In the zoom lens according to the present embodiment, when the third lens unit has positive refractive power, it is preferable that the following formula is satisfied.

[0127] 5.0≤f t / f3≤15.0·····(4)

[0128] in,

[0129] f3: Focal length of the third lens group

[0130] f t : The focal length of a zoom lens at the telephoto end when focusing at infinity

[0131] Formula (4) is a formula for specifying the ratio of the focal length at the telephoto end of the zoom lens when focusing at infinity to the focal length of the third lens group. From the perspective of properly correcting the aberrations at the telephoto end, it is preferable to satisfy Formula (4). In contrast, when the value is lower than the lower limit of Formula (4), although the aberration correction of the third lens group becomes easy, the optical focal length based on the third lens group is sometimes too weak. Therefore, it is sometimes difficult to achieve a high magnification of the zoom lens at the desired full length. In addition, when the value is higher than the upper limit of Formula (4), the optical focal length of the third lens group is sometimes too strong. Therefore, it is sometimes difficult to properly correct the aberrations within the third lens group.

[0132] From the perspective of achieving a higher magnification zoom lens, f t / f3 is more preferably 6.0 or more, and even more preferably 7.0 or more. In order to appropriately correct the aberrations in the third lens group, f t / f3 is more preferably 13.0 or less, and further preferably 11.0 or less.

[0133] The zoom lens according to this embodiment preferably satisfies the following formula.

[0134] 3.0≤|f1 / f2|≤10.0·····(5)

[0135] in,

[0136] f1: Focal length of the first lens group

[0137] f2: Focal length of the second lens group

[0138] Formula (5) is a formula for specifying the ratio of the focal length of the first lens group to the focal length of the second lens group. From the perspective of achieving a high magnification of the zoom lens and appropriately correcting the aberrations at the telephoto end, it is preferable to satisfy Formula (5). In contrast, when the value is lower than the lower limit of Formula (5), although the aberration changes caused by the magnification of the second lens group become smaller, it is sometimes difficult to appropriately correct the aberrations at the telephoto end. In addition, when the value is higher than the upper limit of Formula (5), although the zoom lens is achieved at a high magnification and the aberration correction at the telephoto end becomes easy, the aberration changes caused by the magnification of the second lens group are sometimes too large. Therefore, it is difficult to appropriately correct the aberrations in the entire zoom range.

[0139] To appropriately correct aberrations at the telephoto end, |f1 / f2| is more preferably 4.0 or greater, and even more preferably 5.0 or greater. To appropriately correct aberrations throughout the entire zoom range, |f1 / f2| is more preferably 9.0 or less, and even more preferably 8.0 or less.

[0140] The zoom lens according to this embodiment preferably satisfies the following formula.

[0141] -0.4≤β 2W ≤-0.1·····(6)

[0142] in,

[0143] β 2W : Horizontal magnification of the second lens group at the wide-angle end

[0144] Formula (6) is a formula for specifying the lateral magnification of the second lens group at the wide-angle end. From the perspective of appropriately correcting aberrations at the wide-angle end, it is preferable to satisfy Formula (6). In contrast, when the lower limit of Formula (6) is lower than the lower limit, although aberration correction at the wide-angle end becomes easier, it is sometimes difficult to achieve a wider focal length at the wide-angle end. In addition, when the upper limit of Formula (6) is higher than the upper limit, although it is easier to widen the focal length at the wide-angle end, it is sometimes difficult to appropriately correct aberrations at the wide-angle end.

[0145] From the perspective of achieving a wider focal length at the wide-angle end, β 2W More preferably, it is -0.35 or more, and even more preferably, it is -0.30 or more. In addition, from the perspective of appropriately correcting aberrations at the wide-angle end, β 2W It is more preferably -0.16 or less, and even more preferably -0.18 or less.

[0146] The zoom lens according to this embodiment preferably satisfies the following formula.

[0147] 3.0≤D 2rw / f w ≤9.0·····(7)

[0148] in,

[0149] D 2rw : The distance on the optical axis between the lens surface closest to the image side of the second lens group and the lens surface closest to the object side of the third lens group at the wide-angle end when the zoom lens is focused at infinity.

[0150] f w : The focal length of a zoom lens at the wide-angle end when focusing at infinity

[0151] Formula (7) is a formula for specifying the ratio of the focal length at the wide-angle end when the zoom lens is focused at infinity to the distance on the optical axis between the lens surface closest to the image side of the second lens group and the lens surface closest to the object side of the third lens group at the wide-angle end when the zoom lens is focused at infinity. From the perspective of achieving miniaturization of the zoom lens and making the focal length at the wide-angle end wider, it is preferable to satisfy Formula (7). In contrast, when the value is lower than the lower limit of Formula (7), although miniaturization of the zoom lens becomes easy, widening of the focal length at the wide-angle end is sometimes difficult to achieve. In addition, when the value is higher than the upper limit of Formula (7), although widening of the focal length at the wide-angle end becomes easy, miniaturization of the zoom lens is sometimes difficult to achieve.

[0152] From the perspective of achieving a wider focal length at the wide-angle end, D 2rw / f w It is more preferably 4.0 or more, and even more preferably 5.0 or more. 2rw / f w It is more preferably 8.0 or less, and even more preferably 7.5 or less.

[0153] The zoom lens according to this embodiment preferably satisfies the following formula.

[0154] 2.0≤|m2 / f2|≤6.0·····(8)

[0155] in,

[0156] m2: Movement of the second lens group when zooming from the wide-angle end to the telephoto end

[0157] f2: Focal length of the second lens group

[0158] Formula (8) is a formula for specifying the ratio of the amount of movement of the second lens group when zooming from the wide-angle end to the telephoto end to the focal length of the second lens group. From the perspective of achieving miniaturization of the zoom lens and appropriately correcting aberrations, it is preferable to satisfy Formula (8). In contrast, when the value is lower than the lower limit of Formula (8), although miniaturization of the zoom lens becomes easy, it is sometimes difficult to appropriately correct aberrations. In addition, when the value is higher than the upper limit of Formula (8), although aberration correction in the entire zoom range becomes easy, the amount of movement caused by the zooming of the second lens group is sometimes too large. Therefore, it is sometimes difficult to achieve miniaturization of the zoom lens.

[0159] From the perspective of appropriately correcting aberrations, |m2 / f2| is more preferably 2.5 or greater, and even more preferably 3.0 or greater. Furthermore, from the perspective of miniaturizing the zoom lens, |m2 / f2| is more preferably 5.5 or less, and even more preferably 5.0 or less.

[0160] The zoom lens according to this embodiment preferably satisfies the following formula.

[0161] 0.0<|f p / f n |<1.5·····(9)

[0162] in,

[0163] f p : The focal length of the lens group with the strongest positive refractive power among the rear moving lens groups

[0164] f n : The focal length of the lens group with the strongest negative optical power among the rear moving lens groups

[0165] Formula (9) is a formula for specifying the ratio of the focal length of the lens group with the strongest positive optical focal length among the moving lens groups of the rear group to the focal length of the lens group with the strongest negative optical focal length among the moving lens groups of the rear group. From the perspective of properly correcting the aberration at the wide-angle end, it is preferable to satisfy Formula (9). In contrast, when the value is lower than the lower limit of Formula (9), the range of movement of the lens group with positive optical focal length that is long on the optical axis is reduced, thereby making it easy to miniaturize the zoom lens, but sometimes it is difficult to properly correct the spherical aberration, especially at the wide-angle end. In addition, when the value is higher than the upper limit of Formula (9), it is easy to correct the aberration at the wide-angle end, but sometimes the range of movement of the lens group with positive optical focal length is too large. Therefore, it is sometimes difficult to miniaturize the zoom lens.

[0166] From the perspective of appropriately correcting spherical aberration at the wide-angle end, |f p / f n| is more preferably 0.4 or more, and even more preferably 0.6 or more. In addition, from the perspective of miniaturization of the zoom lens, |f p / f n | It is more preferably 1.4 or less, and further preferably 1.3 or less.

[0167] The zoom lens according to this embodiment preferably satisfies the following formula.

[0168] -2.0<(R b1 -R b2 ) / (R b1 +R b2 )≤2.0·····(10)

[0169] in,

[0170] R b1 : The curvature radius of the object-side surface of the lens closest to the image side

[0171] R b2 : The curvature radius of the image-side surface of the lens positioned closest to the image side

[0172] Formula (10) is a formula for specifying the shape of the lens disposed closest to the image side. From the perspective of reducing ghosting and appropriately correcting aberrations, it is preferable to satisfy Formula (10). In contrast, when the value is below the lower limit of Formula (10), although correction of field curvature aberrations becomes easier, especially at the wide-angle end, it is sometimes difficult to reduce ghosting. Furthermore, when the value is above the upper limit of Formula (10), ghosting can be reduced, but it is sometimes difficult to appropriately correct field curvature aberrations, especially at the wide-angle end.

[0173] In terms of reducing the overlap, (R b1 -R b2 ) / (R b1 +R b2 ) is more preferably -1.8 or more, and further preferably -1.6 or more. In addition, from the perspective of appropriately correcting the field curvature aberration at the wide-angle end, (R b1 -R b2 ) / (R b1 +R b2 ) is more preferably 1.8 or less, and further preferably 1.6 or less.

[0174] 2. Camera

[0175] Next, an imaging device according to one embodiment of the present invention is 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 and configured to convert an optical image formed by the zoom lens into an electrical signal.

[0176] 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 films, etc. can also be used. The imaging device involved in this embodiment is suitable for imaging devices such as digital cameras and video cameras that use the above-mentioned solid-state imaging elements. In addition, the imaging device can be a fixed-lens imaging device in which the lens (lens) is fixed to the housing, or a replaceable-lens imaging device such as a single-lens reflex camera and a mirrorless single-lens camera. In particular, the zoom lens involved in this embodiment can ensure a back focus suitable for replacing the lens system. Therefore, it is suitable for imaging devices such as single-lens reflex cameras that have an optical viewfinder, a phase difference sensor, and a reflector for branching light to these components.

[0177] Figure 21 Schematically shows an example of the structure of the imaging device according to this embodiment. Figure 21 As shown, the mirrorless single-lens camera 1 includes a main body 2 and a lens barrel 3 that is detachably attached to the main body 2. The mirrorless single-lens camera 1 is one form of an imaging device.

[0178] The lens barrel 3 includes a zoom lens 30. The zoom lens 30 includes a first lens group 31, a second lens group 32, a third lens group 33, a fourth lens group 34, and a fifth lens group 35, and is configured to satisfy the above-mentioned equations (1) and (2), for example. Furthermore, an aperture stop 36 is disposed between the second lens group 32 and the third lens group 33.

[0179] The first lens group 31 has positive refractive power, the second lens group 32 has negative refractive power. The third lens group 33 has positive refractive power, the fourth lens group 34 has negative refractive power, and the fifth lens group 35 has positive refractive power. The third lens group 33, the fourth lens group 34, and the fifth lens group 35 correspond to the rear lens group described above.

[0180] The main body 2 includes a CCD sensor 21 as an imaging element and a protective glass 22. The CCD sensor 21 is positioned within the main body 2 so that the optical axis OA of the zoom lens 30 mounted within the lens barrel 3 of the main body 2 is the central axis. The main body 2 may include a parallel flat plate having no substantial optical power instead of the protective glass 22.

[0181] The imaging device according to this embodiment more preferably has an image processing unit that electrically processes the imaging image data obtained by the imaging element to change the shape of the imaging image, and an image correction data holding unit that holds image correction data and an image correction program used to process the imaging image data in the image processing unit.

[0182] When a zoom lens is miniaturized, the shape of the captured image formed on the imaging plane is easily distorted. In this case, it is preferable to correct the distortion of the captured image shape. For example, by having an image correction data storage unit pre-store distortion correction data for correcting the distortion of the captured image shape, the image processing unit can use the distortion correction data stored in the image correction data storage unit to perform this correction. With such an imaging device, the zoom lens can be further miniaturized, beautiful captured images can be obtained, and the overall imaging device can be miniaturized.

[0183] Furthermore, in the imaging device according to this embodiment, the image correction data storage unit preferably stores magnification chromatic aberration correction data in advance. Furthermore, the image processing unit preferably uses the magnification chromatic aberration correction data stored in the image correction data storage unit to perform magnification chromatic aberration correction on the captured image. Correcting magnification chromatic aberration, i.e., color distortion, by the image processing unit can reduce the number of lenses comprising the optical system. Therefore, with such an imaging device, it is possible to further miniaturize the zoom lens, obtain beautiful captured images, and achieve miniaturization of the imaging device as a whole.

[0184] The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0185] [Example]

[0186] The following describes an embodiment of the present invention. In the following tables, the unit of length is "mm" and the unit of field angle is "°". In addition, "E+a" means "×10 a ”.

[0187] [Example 1]

[0188] Figure 1 These diagrams show cross-sections of the zoom lens of Example 1 when focused at infinity at the wide-angle and telephoto positions. The zoom lens of Example 1 is composed, in order from the object side, of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, and a fifth lens group G5 with positive refractive power. A stop S is disposed between lens group G2 and lens group G3. Figure 1 The indicated “IMG” is an image plane (imaging surface), and a cover glass CG is disposed between the fifth lens group G5 and the image plane IMG. Figure 1The "F" in represents a focus group, and in the zoom lens of Example 1, the fourth lens group G4 is the focus group. Furthermore, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 correspond to the aforementioned rear group.

[0189] The zoom lens of Example 1 performs zooming by changing the air space between each lens group. In the figure, the arrows shown below each lens group at the wide-angle end indicate the movement trajectory of each lens group when moving from the wide-angle end to the telephoto end. When zooming from the wide-angle end to the intermediate focal length state, the first lens group G1 and the third lens group G3 do not move, and the second lens group G2, the fourth lens group G4, and the fifth lens group G5 move toward the image side. When zooming from the intermediate focal length state to the telephoto end, the first lens group G1 and the third lens group G3 do not move, and the second lens group G2 and the fifth lens group G5 move toward the image side, and the fourth lens group G4 moves toward the object side. Among the moving lens groups in the rear group, the lens group with the strongest positive optical power is the fifth lens group G5, and among the moving lens groups in the rear group, the lens group with the strongest negative optical power is the fourth lens group G4.

[0190] Next, an example of specific numerical values ​​applied to the zoom lens will be described. Table 1 is a table showing surface data of the zoom lens of Example 1.

[0191] In the table of surface data, "No." represents the serial number of the lens surface counted from the object side, "r" represents the radius of curvature of the lens surface, "d" represents the distance on the optical axis of the lens surface, "Nd" represents the refractive index corresponding to the d-line (wavelength λ = 587.56nm), "vd" represents the Abbe number corresponding to the d-line, and "H" represents the effective radius. In addition, "*" in the surface number indicates that the lens surface is aspherical, and "S" indicates that it is an aperture. Furthermore, the column "d" shows "D(7)", "D(14)", etc., which means that the distance on the optical axis of the lens surface is a variable distance that changes when changing magnification or focusing.

[0192] In addition, "INF" for the radius of curvature indicates a flat surface. In Table 1, Nos. 1 to 7 are the surface numbers of the first lens group G1, Nos. 8 to 14 are the surface numbers of the second lens group G2, and No. 15 represents the aperture. Nos. 16 to 20 are the surface numbers of the third lens group G3, and Nos. 21 to 23 are the surface numbers of the fourth lens group G4. Nos. 24 to 28 are the surface numbers of the fifth lens group G5. No. 26 is the object-side lens surface of the lens positioned closest to the image side, and No. 28 is the image-side lens surface of the lens positioned closest to the image side. Nos. 29 and 30 represent the cover glass CG, and No. 31 represents the image surface.

[0193] [Table 1]

[0194]

[0195]

[0196]

[0197] Table 2 shows the various specifications of the zoom lens of Example 1. This table shows, from the left, the values ​​for the wide-angle position, the intermediate focal length position, and the telephoto position. In this table, "f" represents the focal length of the zoom lens when focused at infinity, "FNO" represents the F-number, and "ω" represents the half-angle of view. Furthermore, "D(n)" (n is an integer) represents the variable distance on the optical axis of the zoom lens during zooming.

[0198] [Table 2]

[0199] f 6.7540 78.3064 155.8625 FNO 1.6473 4.3760 4.9900 ω 32.9390 3.2298 1.6576 D(7) 0.9550 32.2686 37.2483 D(14) 37.5933 6.2797 1.3000 D(20) 1.4290 13.7638 9.6363 D(23) 14.6550 5.7445 13.0704 D(28) 10.2223 6.7981 3.5999

[0200] Table 3 is a table showing the aspheric coefficients of each aspheric surface in the zoom lens of Example 1. The aspheric coefficients in this table are values ​​when the shape of each aspheric surface is defined by the following equations.

[0201] [Formula] z=ch 2 / [1+{1-(1+K)c 2 h 2} 1 / 2 ]+A4h 4 +A6h 6 +A8h 8 +A10h 10 +A12h 12 +A14h 14 +A16h 16 +A18h 18 +A20h 20

[0202] In the above formula, "z" is the displacement of the aspheric surface in the direction of the optical axis relative to a reference plane perpendicular to the optical axis, "c" is the curvature (1 / r), "h" is the height relative to the optical axis, "K" is the conic coefficient, and "An" (n is an integer) is the nth-order aspheric coefficient. The aspheric coefficients of surface numbers not shown are 0.

[0203] [Table 3]

[0204] No. K A4 A6 A8 A10 13 -6.82425E+00 6.71059E-05 -1.28979E-06 -2.21950E-08 3.79256E-10 14 -10.00000E+00 9.90165E-05 -1.85285E-06 1.80642E-10 -2.47129E-11 16 7.23002E-02 -1.00114E-05 -1.73186E-07 2.06559E-09 -2.15916E-12 17 2.86949E+00 4.23935E-05 -1.39545E-07 2.20987E-09 -1.60939E-12 24 -1.53905E+00 -6.74771E-06 2.25878E-07 -2.25906E-09 7.72606E-11 25 -1.45478E+00 9.15364E-05 -2.36607E-07 -1.01907E-08 2.15078E-10 No. A12 A14 A16 A18 A20 13 -1.27271E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 14 1.69396E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 17 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 24 -3.53885E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 25 -4.16134E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

[0205] Table 4 shows the focal lengths of the lens units constituting the zoom lens of Example 1.

[0206] [Table 4]

[0207]

[0208]

[0209] in addition, Figure 2 、 Figure 3 and Figure 4 These graphs show the longitudinal aberrations of the zoom lens of Example 1 at the wide-angle position, at intermediate focal lengths, and at infinity focus at the telephoto position. The graphs showing longitudinal aberrations in each figure are, from the left in the figure, spherical aberration (SA (mm)), astigmatism (AST (mm)), and distortion (DIS (%)). The same applies to the other examples.

[0210] In the graph showing spherical aberration, the vertical axis represents F-number, and the horizontal axis represents defocus. The solid line represents spherical aberration at the d-line (wavelength λ = 587.56 nm), the short-dashed line represents spherical aberration at the F-line (wavelength λ = 486.13 nm), and the long-dashed line represents spherical aberration at the C-line (wavelength λ = 656.28 nm).

[0211] In the graph showing astigmatism, the vertical axis represents the half field angle, and the horizontal axis represents defocus. In the graph showing astigmatism, the solid line represents astigmatism at the sagittal image plane corresponding to the d-line (indicated by S in the graph), and the dotted line represents astigmatism at the meridional plane corresponding to the d-line (indicated by T in the graph).

[0212] In the graph showing distortion, the vertical axis represents the half angle of view, and the horizontal axis represents %.

[0213] [Example 2]

[0214] Figure 5 These are diagrams schematically showing the optical structure of the zoom lens of Example 2 when focusing at infinity at the wide-angle limit and the telephoto limit. Figure 6 、 Figure 7 and Figure 8 These diagrams respectively show the longitudinal aberrations of the zoom lens of Example 2 at the wide-angle end, at the intermediate focal length, and when focused at infinity at the telephoto end. The zoom lens of Example 2 is composed, from the object side, of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, and a sixth lens group G6 with negative refractive power. An aperture stop S is disposed between lens group G2 and lens group G3. In the zoom lens of Example 2, the fourth lens group G4 serves as the focusing group. Furthermore, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the aforementioned rear lens group.

[0215] The zoom lens of Example 2 performs zooming by changing the air space between each lens group. When zooming from the wide-angle end to the intermediate focal length state, the first lens group G1, the third lens group G3, and the sixth lens group G6 do not move, while the second lens group G2, the fourth lens group G4, and the fifth lens group G5 each move toward the image side. When zooming from the intermediate focal length state to the telephoto end, the first lens group G1, the third lens group G3, and the sixth lens group G6 do not move, while the second lens group G2 and the fifth lens group G5 each move toward the image side, and the fourth lens group G4 moves toward the object side. Among the moving lens groups in the rear group, the lens group with the strongest positive optical power is the fifth lens group G5, and among the moving lens groups in the rear group, the lens group with the strongest negative optical power is the fourth lens group G4.

[0216] Table 5 shows surface data for the zoom lens of Example 2. In Table 2, Nos. 1 to 7 are the surface numbers of the first lens group G1, Nos. 8 to 14 are the surface numbers of the second lens group G2, and No. 15 represents the aperture stop. Nos. 16 to 20 are the surface numbers of the third lens group G3, Nos. 21 to 23 are the surface numbers of the fourth lens group G4, and Nos. 24 to 28 are the surface numbers of the fifth lens group G5. Nos. 29 and 30 are the surface numbers of the sixth lens group G6. No. 29 is the object-side lens surface of the lens positioned closest to the image side, and No. 30 is the image-side lens surface of the lens positioned closest to the image side. Nos. 31 and 32 represent the cover glass CG, and No. 33 represents the image surface.

[0217] [Table 5]

[0218]

[0219]

[0220]

[0221] Table 6 shows various specifications of the zoom lens of Example 2. Table 7 shows the aspheric coefficients of the aspheric surfaces of the zoom lens of Example 2. Table 8 shows the focal lengths of the lens units constituting the zoom lens of Example 2.

[0222] [Table 6]

[0223] f 6.7582 78.7812 156.0507 FNO 1.6473 4.3760 4.9900 ω 35.6868 3.2654 1.6611 D(7) 1.1343 32.1670 37.3748 D(14) 37.5405 6.5078 1.3000 D(20) 1.0191 14.4315 10.2661 D(23) 15.3822 5.7863 12.3669 D(28) 7.5316 3.7152 1.3000

[0224] [Table 7]

[0225]

[0226]

[0227] [Table 8]

[0228] lens group Face number focal length G1 1-7 57.9427 G2 8-14 -9.04449 G3 16-20 16.5244 G4 21-23 -18.8028 G5 24-28 18.0092 G6 29-30 -32.1836

[0229] [Example 3]

[0230] Figure 9 These are diagrams schematically showing the optical structure of the zoom lens of Example 3 when focusing at infinity at the wide-angle limit and the telephoto limit. Figure 10 、 Figure 11 and Figure 12 These diagrams respectively show the longitudinal aberrations of the zoom lens of Example 3 at the wide-angle end, at intermediate focal lengths, and when focused at infinity at the telephoto end. The zoom lens of Example 3 is composed, from the object side, of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, and a sixth lens group G6 with negative refractive power. An aperture stop S is disposed between lens group G2 and lens group G3. In the zoom lens of Example 3, the fourth lens group G4 serves as a focusing group. Furthermore, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the aforementioned rear lens group.

[0231] The zoom lens of Example 3 performs zooming by changing the air spaces between the lens groups. When zooming from the wide-angle end to the intermediate focal length, the first lens group G1 and the third lens group G3 do not move, while the second lens group G2, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each move toward the image side. When zooming from the intermediate focal length to the telephoto end, the first lens group G1 and the third lens group G3 do not move, while the second lens group G2, the fifth lens group G5, and the sixth lens group G6 each move toward the image side, and the fourth lens group G4 moves toward the object side. Among the rear moving lens groups, the lens group with the strongest positive optical power is the fifth lens group G5, and among the rear moving lens groups, the lens group with the strongest negative optical power is the fourth lens group G4.

[0232] Table 9 shows surface data for the zoom lens of Example 3. In Table 9, Nos. 1 to 7 are the surface numbers of the first lens group G1, Nos. 8 to 14 are the surface numbers of the second lens group G2, and No. 15 represents the aperture stop. Nos. 16 to 20 are the surface numbers of the third lens group G3, Nos. 21 to 23 are the surface numbers of the fourth lens group G4, and Nos. 24 and 25 are the surface numbers of the fifth lens group G5. Nos. 26 to 28 are the surface numbers of the sixth lens group G6. No. 26 is the object-side lens surface of the lens positioned closest to the image side, and No. 28 is the image-side lens surface of the lens positioned closest to the image side. Nos. 29 and 30 represent the cover glass CG, and No. 31 represents the image surface.

[0233] [Table 9]

[0234]

[0235]

[0236]

[0237] Table 10 shows various specifications of the zoom lens of Example 3. Table 11 shows the aspheric coefficients of the aspheric surfaces of the zoom lens of Example 3. Table 12 shows the focal lengths of the lens units constituting the zoom lens of Example 3.

[0238] [Table 10]

[0239] f 6.7560 78.6762 155.8895 FNO 1.6473 4.3760 4.9900 ω 32.8557 3.2148 1.6566 D(7) 0.9550 32.3100 37.2374 D(14) 37.5827 6.2275 1.3000 D(20) 1.4206 13.7269 9.6969 D(23) 14.6753 5.7776 13.0033 D(25) 0.1219 0.1200 0.1237 D(28) 10.2161 6.8089 3.6095

[0240] [Table 11]

[0241]

[0242]

[0243] [Table 12]

[0244] lens group Face number focal length G1 1-7 58.1668 G2 8-14 -8.6581 G3 16-20 15.8453 G4 21-23 -18.2998 G5 24-25 15.3124 G6 26-28 -124.964

[0245] [Example 4]

[0246] Figure 13 These are diagrams schematically showing the optical structure of the zoom lens of Example 4 when focusing at infinity at the wide-angle limit and the telephoto limit. Figure 14 、 Figure 15 and Figure 16 These diagrams respectively show the longitudinal aberrations of the zoom lens of Example 4 at the wide-angle end, at the intermediate focal length, and when focused at infinity at the telephoto end. The zoom lens of Example 4 is composed, from the object side, of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with negative refractive power, a fifth lens group G5 with positive refractive power, a sixth lens group G6 with positive refractive power, and a seventh lens group G7 with negative refractive power. An aperture stop S is disposed between lens group G2 and lens group G3. In the zoom lens of Example 4, the fourth lens group G4 serves as the focusing group. Furthermore, the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 correspond to the aforementioned rear lens group.

[0247] The zoom lens of Example 4 performs zooming by varying the air spaces between the lens groups. When zooming from the wide-angle end to the intermediate focal length, the first lens group G1, the third lens group G3, and the seventh lens group G7 remain stationary, while the second lens group G2, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 each move toward the image side. When zooming from the intermediate focal length to the telephoto end, the first lens group G1, the third lens group G3, and the seventh lens group G7 remain stationary, while the second lens group G2, the fifth lens group G5, and the sixth lens group G6 each move toward the image side, and the fourth lens group G4 moves toward the object side. Among the rear moving lens groups, the fifth lens group G5 has the strongest positive refractive power, and among the rear moving lens groups, the fourth lens group G4 has the strongest negative refractive power.

[0248] Table 13 shows surface data for the zoom lens of Example 4. In Table 2, Nos. 1 to 7 are the surface numbers of the first lens group G1, Nos. 8 to 14 are the surface numbers of the second lens group G2, and No. 15 represents the aperture stop. Nos. 16 to 20 are the surface numbers of the third lens group G3, Nos. 21 to 23 are the surface numbers of the fourth lens group G4, Nos. 24 and 25 are the surface numbers of the fifth lens group G5, and Nos. 26 to 28 are the surface numbers of the sixth lens group G6. Nos. 29 and 30 are the surface numbers of the seventh lens group G7. No. 29 is the object-side lens surface of the lens positioned closest to the image side, and No. 30 is the image-side lens surface of the lens positioned closest to the image side. Nos. 31 and 32 represent the cover glass CG, and No. 33 represents the image surface.

[0249] [Table 13]

[0250]

[0251]

[0252]

[0253] Table 14 shows various specifications of the zoom lens of Example 4. Table 15 shows the aspheric coefficients of the aspheric surfaces of the zoom lens of Example 4. Table 16 shows the focal lengths of the lens units constituting the zoom lens of Example 4.

[0254] [Table 14]

[0255] f 6.7582 78.8393 156.0496 FNO 1.6473 4.3760 4.9900 ω 35.4566 3.2622 1.6617 D(7) 1.1251 32.1702 37.3585 D(14) 37.5334 6.4883 1.3000 D(20) 0.9935 14.4336 10.3298 D(23) 15.3179 5.7809 12.3186 D(25) 0.2730 0.1151 0.0972 D(28) 7.4612 3.7161 1.3000

[0256] [Table 15]

[0257]

[0258]

[0259] [Table 16]

[0260] lens group Face number focal length G1 1-7 57.9741 G2 8-14 -9.04893 G3 16-20 16.5165 G4 21-23 -18.8153 G5 24-25 19.6069 G6 26-28 85.0052 G7 29-30 -32.2053

[0261] [Example 5]

[0262] Figure 17 These are diagrams schematically showing the optical structure of the zoom lens of Example 5 when focusing at infinity at the wide-angle limit and the telephoto limit. Figure 18 、 Figure 19 and Figure 20 These diagrams respectively show the longitudinal aberrations of the zoom lens of Example 5 at the wide-angle end, at the intermediate focal length, and when focused at infinity at the telephoto end. The zoom lens of Example 5 is composed, from the object side, of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a sixth lens group G6 with positive refractive power. An aperture stop S is disposed between lens group G2 and lens group G3. In the zoom lens of Example 5, the fifth lens group G5 serves as the focusing group. The third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the aforementioned rear lens group.

[0263] The zoom lens of Example 5 performs zooming by varying the air spaces between the lens groups. When zooming from the wide-angle end to the intermediate focal length, the first lens group G1 and the third lens group G3 remain stationary, the second lens group G2, the fifth lens group G5, and the sixth lens group G6 each move toward the image side, and the fourth lens group G4 moves toward the object side. When zooming from the intermediate focal length to the telephoto end, the first lens group G1 and the third lens group G3 remain stationary, the second lens group G2 and the sixth lens group G6 each move toward the image side, and the fourth lens group G4 and the fifth lens group G5 each move toward the object side. Among the rear moving lens groups, the sixth lens group G6 has the strongest positive refractive power, and the fifth lens group G5 has the strongest negative refractive power.

[0264] Table 17 shows surface data for the zoom lens of Example 5. In Table 17, Nos. 1 to 7 are the surface numbers of the first lens group G1, Nos. 8 to 14 are the surface numbers of the second lens group G2, and No. 15 represents the aperture stop. Nos. 16 and 17 are the surface numbers of the third lens group G3, Nos. 18 to 20 are the surface numbers of the fourth lens group G4, and Nos. 21 to 23 are the surface numbers of the fifth lens group G5. Nos. 24 to 28 are the surface numbers of the sixth lens group G6. No. 26 is the object-side lens surface of the lens positioned closest to the image side, and No. 28 is the image-side lens surface of the lens positioned closest to the image side. Nos. 29 and 30 represent the cover glass CG, and No. 31 represents the image surface.

[0265] [Table 17]

[0266]

[0267]

[0268]

[0269] Table 18 shows various specifications of the zoom lens of Example 5. Table 19 shows the aspheric coefficients of the aspheric surfaces of the zoom lens of Example 5. Table 20 shows the focal lengths of the lens units constituting the zoom lens of Example 5.

[0270] [Table 18]

[0271] f 6.7543 78.2486 155.8677 FNO 1.6473 4.3760 4.9900 ω 32.5662 3.2253 1.6534 D(7) 0.9550 32.2390 37.1781 D(14) 37.5228 6.2388 1.3000 D(17) 0.6342 0.1461 0.1000 D(20) 1.3310 13.6460 9.5776 D(23) 14.7191 5.8101 13.1992 D(28) 9.9245 7.0067 3.7325

[0272] [Table 19]

[0273] No. K A4 A6 A8 A10 13 -10.00000E+00 8.24372E-05 -1.57495E-06 -2.57052E-08 3.53377E-10 14 -10.00000E+00 1.29115E-04 -2.26299E-06 -3.45755E-09 -5.40676E-12 16 2.53877E-01 -9.64441E-06 -2.06637E-07 1.69045E-09 -3.20026E-12 17 3.40190E+00 3.83659E-05 -1.34583E-07 1.77975E-09 -9.96365E-13 24 -3.99145E+00 -2.12824E-05 2.41414E-07 -4.00299E-09 1.46678E-10 25 -1.30634E+00 8.47347E-05 -2.27748E-07 -9.68102E-09 2.49400E-10 No. A12 A14 A16 A18 A20 13 -4.12094E-13 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 14 2.05108E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 17 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 24 -3.05431E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 25 -3.45085E-12 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00

[0274] [Table 20]

[0275]

[0276]

[0277] Table 21 shows the calculated values ​​based on the above-mentioned formulas in Examples 1 to 5 and the numerical values ​​used in the formulas.

[0278] [Table 21]

[0279]

[0280]

Claims

1. A zoom lens, comprising, from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear lens group having positive refractive power as a whole, wherein the zoom operation is performed by changing the intervals between adjacent lens groups. The rear lens group includes at least the third lens group, the fourth lens group and the fifth lens group in order from the object side. One of the third lens group, the fourth lens group, and the fifth lens group is a focusing group that performs focusing by moving on the optical axis. The zoom lens satisfies the following equation: 0.3≤|f f | / M<0.8・・・・・(1) 1.5≤β FW / β FT ＜7.0・・・・・（2） in, M:f w With f t The square root of the product f f : Focal length of the focusing group f w : The focal length of the zoom lens at the wide-angle end when focusing at infinity f t : The focal length of the zoom lens at the telephoto end when focusing at infinity β FW : The horizontal magnification of the focusing group at the wide-angle end β FT : The horizontal magnification of the focusing group at the telephoto end.

2. The zoom lens according to claim 1, Satisfy the following formula: 5.0≤β 2T / β 2W ≤40.0・・・・・（3） in, β 2T : The lateral magnification of the second lens group at the telephoto end β 2W : The lateral magnification of the second lens group at the wide-angle end.

3. The zoom lens according to claim 1 or 2, The third lens group has positive optical power. The zoom lens satisfies the following equation: 5.0≤f t / f3≤15.0・・・・・(4) in, f3: focal length of the third lens group.

4. The zoom lens according to claim 1, Satisfy the following formula: 3.0≤|f1 / f2|≤10.0・・・・・(5) in, f1: focal length of the first lens group f2: focal length of the second lens group.

5. The zoom lens according to claim 1, Satisfy the following formula: －0.4≤β 2W ≤－0.1・・・・・（6） in, β 2W : The lateral magnification of the second lens group at the wide-angle end.

6. The zoom lens according to claim 1, Satisfy the following formula: 3.0≤D 2rw / f w ≤9.0・・・・・(7) in, D 2rw : The distance on the optical axis between the lens surface of the second lens group closest to the image side and the lens surface of the third lens group closest to the object side at the wide-angle end when the zoom lens is focused at infinity.

7. The zoom lens according to claim 1, Satisfy the following formula: 2.0≤|m2 / f2|≤6.0・・・・(8) in, m2: The amount of movement of the second lens group when changing magnification from the wide-angle end to the telephoto end f2: focal length of the second lens group.

8. The zoom lens according to claim 1, At least two lens groups in the rear group move on the optical axis when zooming from a wide-angle end to a telephoto end.

9. The zoom lens according to claim 8, The movable lens group of the rear group includes at least one lens group with positive optical power and at least one lens group with negative optical power, The zoom lens satisfies the following equation: 0.0<|f p / f n |<1.5・・・・・(9) in, f p : The focal length of the lens group with the strongest positive optical power among the moving lens groups of the rear group f n : The focal length of the lens group with the strongest negative optical power among the moving lens groups of the rear group.

10. The zoom lens according to claim 1, Satisfy the following formula: -2.0<(R b1 -R b2 ) / (R b1 +R b2 )≤2.0・・・・・(10) in, R b1 : The curvature radius of the object-side surface of the lens closest to the image side of the zoom lens R b2 : The curvature radius of the image-side surface of the lens arranged closest to the image side of the zoom lens.

11. A camera device comprising: A zoom lens according to any one of claims 1 to 10, and an imaging element provided on the image side of the zoom lens and configured to convert an optical image formed by the zoom lens into an electrical signal.

Images