Variable magnification optical system, optical apparatus, and method for manufacturing variable magnification optical system

Abstract

The variable magnification optical system (ZL) has 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 positive refractive power arranged in order from the object side along the optical axis, the first lens group (G1) being fixed with respect to the image plane during magnification change, the second lens group (G2) being fixed with respect to the image plane, and the third lens group (G3) being fixed with respect to the image plane during magnification change. The variable magnification optical system (ZL) satisfies the following conditional expression: 0.70 < (-f1) / f2 < 1.30, 0.55 < f2 / (-f3) < 1.20, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and f3 is the focal length of the third lens group.

Description

Technical Field

[0001] The invention relates to a variable-magnification optical system, an optical device and a method for manufacturing the variable-magnification optical system. Background Art

[0002] Conventionally, there have been proposed variable-power optical systems suitable for still cameras, electronic still cameras, video cameras, etc. (see, for example, Patent Document 1). However, in such variable-power optical systems, it is difficult to achieve good optical performance while achieving miniaturization.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-040029 Summary of the invention

[0006] The variable power optical system of the present invention comprises a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group having positive optical power, which are arranged in sequence from the object side along the optical axis, wherein when variable power is performed, the first lens group is fixed relative to the image plane, and the intervals between adjacent lens groups are changed, and the variable power optical system satisfies the following conditional expression: 0.70<(-f1) / f2<1.30 0.55<f2 / (-f3)<1.20 Wherein, f1: the focal length of the first lens group, f2: focal length of the second lens group, f3: focal length of the third lens group.

[0007] The optical device according to the present invention is configured to include the above-mentioned variable magnification optical system.

[0008] The present invention relates to a method for manufacturing a variable power optical system, the variable power optical system comprising a first lens group with negative optical power, a second lens group with positive optical power, a third lens group with negative optical power, and a fourth lens group with positive optical power arranged in sequence from the object side along the optical axis, wherein when the zoom is performed, the first lens group is fixed relative to the image plane, and the intervals between adjacent lens groups are changed, and the method for manufacturing the variable power optical system comprises the steps of arranging the lenses in the lens barrel in a manner that satisfies the following conditional expression: 0.70<(-f1) / f2<1.30 0.55<f2 / (-f3)<1.20 Wherein, f1: focal length of the first lens group f2: focal length of the second lens group f3: focal length of the third lens group BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 1 is a diagram showing the lens structure of the variable power optical system according to the first embodiment in the wide-angle end state.

[0010] Figure 2 These are diagrams showing various aberrations when the variable power optical system according to the first embodiment is in focus at infinity at the wide angle end.

[0011] Figure 3 These are diagrams showing various aberrations when the variable power optical system according to the first embodiment is in the telephoto end state and is in focus at infinity.

[0012] Figure 4 It is a lens structure diagram of the variable power optical system involved in the second embodiment in the wide-angle end state.

[0013] Figure 5 1 and 10 are diagrams showing various aberrations of the variable power optical system according to the second embodiment when the system is in focus at infinity at the wide angle end.

[0014] Figure 6 1 and 10 are diagrams showing various aberrations when the variable power optical system according to the second embodiment is in the telephoto end state and is in focus at infinity.

[0015] Figure 7 It is a lens structure diagram of the variable power optical system involved in the third embodiment in the wide-angle end state.

[0016] Figure 8 1 and 10 are diagrams showing various aberrations of the variable power optical system according to the third embodiment when the system is in focus at infinity at the wide angle end.

[0017] Fig. 9 1 and 10 are diagrams showing various aberrations when the zoom optical system according to the third embodiment is in the telephoto end state and is in focus at infinity.

[0018] Fig.10 It is a lens structure diagram of the variable power optical system involved in the fourth embodiment in the wide-angle end state.

[0019] Fig.11 1 and 10 are diagrams showing various aberrations of the variable power optical system according to the fourth embodiment when the zoom lens is in the wide-angle end state and in focus at infinity.

[0020] Fig.12 1 and 10 are diagrams showing various aberrations when the zoom optical system according to the fourth embodiment is in the telephoto end state and is in focus at infinity.

[0021] Fig.13 It is a lens structure diagram of the variable power optical system involved in the fifth embodiment in the wide-angle end state.

[0022] Fig.14 1 and 10 are diagrams showing various aberrations of the variable power optical system according to the fifth embodiment when focusing at infinity at the wide angle end.

[0023] Fig.15 These are diagrams of various aberrations when focusing at infinity at the telephoto end state of the variable power optical system involved in the fifth embodiment.

[0024] Fig.16 This is a lens structure diagram of the variable power optical system involved in the sixth embodiment in the wide-angle end state.

[0025] Fig.17 1 and 10 are diagrams showing various aberrations of the variable power optical system according to the sixth embodiment when focusing at infinity at the wide angle end.

[0026] Fig.18 These are diagrams of various aberrations when focusing at infinity at the telephoto end state of the variable power optical system involved in the sixth embodiment.

[0027] Fig.19 It is a diagram showing the structure of a camera including a variable power optical system according to each embodiment.

[0028] Fig. 20 This is a flowchart showing a method for manufacturing a variable power optical system according to the present invention. DETAILED DESCRIPTION

[0029] Hereinafter, preferred embodiments of the present invention will be described. Fig.19 A camera (optical device) having a variable magnification optical system according to each embodiment will be described. Fig.19 As shown in FIG. 1 , the digital camera body 2 is composed of a main body 2 and a photographic lens 3 mounted on the main body 2. The main body 2 includes an imaging element 4, a main body control unit (not shown) for controlling the operation of the digital camera, and a liquid crystal screen 5. The photographic lens 3 includes a variable magnification optical system ZL composed of a plurality of lens groups and a lens position control mechanism (not shown) for controlling the position of each lens group. The lens position control mechanism is composed of a sensor for detecting the position of the lens group, a motor for moving the lens group forward and backward along the optical axis, and a control circuit for driving the motor.

[0030] The light from the subject is focused by the variable magnification optical system ZL of the photographic lens 3 and reaches the image plane I of the imaging element 4. The light from the subject reaching the image plane I is photoelectrically converted by the imaging element 4 and recorded as digital image data in a memory (not shown). The digital image data recorded in the memory can be displayed on the liquid crystal screen 5 according to the user's operation. In addition, the camera can be a mirrorless camera or a single-lens reflex camera with a quick return mirror. In addition, Fig.19The variable power optical system ZL shown schematically shows the variable power optical system included in the photographic lens 3 , and the lens structure of the variable power optical system ZL is not limited to this structure.

[0031] Next, the variable magnification optical system according to the present embodiment will be described. As an example of the variable magnification optical system (zoom lens) ZL according to the present embodiment, a variable magnification optical system ZL (1) is shown as follows: Figure 1 As shown, the lens comprises a first lens group with negative optical focal power, a second lens group with positive optical focal power, a third lens group with negative optical focal power and a fourth lens group with positive optical focal power arranged from the object side along the optical axis. When changing the magnification, the first lens group is fixed relative to the image plane and the intervals between adjacent lens groups change.

[0032] The variable power optical system ZL according to the present embodiment satisfies the following conditional expressions (1) and (2) under the above-mentioned configuration.

[0033] 0.70<(-f1) / f2<1.30 …(1) 0.55<f2 / (-f3)<1.20 …(2) Where, f1: focal length of the first lens group f2: Focal length of the second lens group f3: Focal length of the third lens group

[0034] According to this embodiment, a small-sized variable-power optical system with good optical performance and an optical device having the variable-power optical system can be obtained. For example, an optical device having a dynamic image shooting function can be equipped with the variable-power optical system of this embodiment, thereby achieving a small-sized variable-power optical system with good optical performance. The variable-power optical system ZL of this embodiment can be Figure 4 The variable magnification optical system ZL(2) shown can also be Figure 7 The variable magnification optical system ZL(3) shown can also be Fig.10 The variable magnification optical system ZL(4) shown can also be Fig.13 The variable magnification optical system ZL(5) shown in FIG. Fig.16 The variable magnification optical system ZL (6) shown.

[0035] Conditional expression (1) is a conditional expression for defining the ratio of the focal length f1 of the first lens group to the focal length f2 of the second lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (1), spherical aberration, coma, and field curvature can be corrected well.

[0036] When the corresponding value of conditional expression (1) is lower than the lower limit, the optical power of the first lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the lower limit of conditional expression (1) to 0.75 or 0.80, the effect of this embodiment can be made more reliable.

[0037] On the other hand, when the corresponding value of conditional expression (1) exceeds the upper limit, the optical power of the second lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (1) to 1.25 or 1.20, the effect of this embodiment can be made more reliable.

[0038] Conditional expression (2) is a conditional expression for defining the ratio of the focal length f2 of the second lens group to the focal length f3 of the third lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (2), spherical aberration, coma and field curvature can be corrected well.

[0039] In a zoom optical system, when the corresponding value of conditional expression (2) is lower than the lower limit value, the optical power of the second lens group becomes larger, and correction of spherical aberration, coma and image curvature becomes difficult, which is not preferred. By setting the lower limit value of conditional expression (2) to 0.60 or 0.65, the effect of this embodiment can be made more reliable.

[0040] On the other hand, when the corresponding value of conditional expression (2) exceeds the upper limit, the power of the third lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (2) to 1.10 or 1.00, the effect of this embodiment can be made more reliable.

[0041] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (3) is satisfied.

[0042] 0.20<(-f1) / f4<0.50 …(3) Where, f4: focal length of the 4th lens group

[0043] Conditional expression (3) is a conditional expression for defining the ratio of the focal length f1 of the first lens group to the focal length f4 of the fourth lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (3), spherical aberration, coma, and field curvature can be corrected well.

[0044] When the corresponding value of conditional expression (3) is lower than the lower limit, the optical power of the first lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the lower limit of conditional expression (3) to 0.25 or 0.30, the effect of this embodiment can be made more reliable.

[0045] On the other hand, when the corresponding value of conditional expression (3) exceeds the upper limit, the optical power of the fourth lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (3) to 0.45 or 0.42, the effect of this embodiment can be made more reliable.

[0046] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (4) is satisfied.

[0047] 0.20<(-f3) / f4<0.90 …(4) Where, f4: focal length of the 4th lens group

[0048] Conditional expression (4) is a conditional expression for defining the ratio of the focal length f3 of the third lens group to the focal length f4 of the fourth lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (4), spherical aberration, coma and field curvature can be corrected well.

[0049] When the corresponding value of conditional expression (4) is lower than the lower limit, the optical power of the third lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the lower limit of conditional expression (4) to 0.25 or 0.30, the effect of this embodiment can be made more reliable.

[0050] On the other hand, when the corresponding value of conditional expression (4) exceeds the upper limit, the optical power of the fourth lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (4) to 0.80 or 0.70, the effect of this embodiment can be made more reliable.

[0051] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (5) is satisfied.

[0052] 0.50<f1 / f3<1.10 …(5)

[0053] Conditional expression (5) is a conditional expression for defining the ratio of the focal length f1 of the first lens group to the focal length f3 of the third lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (5), spherical aberration, coma, and field curvature can be corrected well.

[0054] When the corresponding value of conditional expression (5) is lower than the lower limit, the optical power of the first lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the lower limit of conditional expression (5) to 0.55 or 0.60, the effect of this embodiment can be made more reliable.

[0055] On the other hand, when the corresponding value of conditional expression (5) exceeds the upper limit, the power of the third lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (5) to 1.00 or 0.90, the effect of this embodiment can be made more reliable.

[0056] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (6) is satisfied.

[0057] 0.20<f2 / f4<0.70 …(6) Where, f4: focal length of the 4th lens group

[0058] Conditional expression (6) is a conditional expression for defining the ratio of the focal length f2 of the second lens group to the focal length f4 of the fourth lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (6), spherical aberration, coma and field curvature can be corrected well.

[0059] When the corresponding value of conditional expression (6) is lower than the lower limit, the optical power of the second lens group becomes larger, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the lower limit of conditional expression (6) to 0.25 or 0.30, the effect of this embodiment can be made more reliable.

[0060] On the other hand, when the corresponding value of conditional expression (6) exceeds the upper limit, the power of the fourth lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (6) to 0.60 or 0.50, the effect of this embodiment can be made more reliable.

[0061] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (7) is satisfied.

[0062] 0.120<fw / TLw<0.190 …(7) Where, fw: focal length of the zoom optical system at the wide-angle end TLw: The total length of the zoom optical system at the wide-angle end

[0063] Conditional expression (7) is a conditional expression for defining a ratio of the focal length fw of the variable power optical system in the wide-angle end state in the variable power optical system ZL to the total length TLw of the variable power optical system ZL in the wide-angle end state and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (7), a variable power optical system with high optical performance can be realized while achieving miniaturization.

[0064] When the corresponding value of conditional expression (7) is lower than the lower limit, it becomes difficult to realize a variable magnification optical system with good optical performance while achieving miniaturization. By setting the lower limit of conditional expression (7) to 0.125 or 0.130, the effect of this embodiment can be made more reliable.

[0065] When the corresponding value of conditional expression (7) exceeds the upper limit, it becomes difficult to realize a variable power optical system with good optical performance while achieving miniaturization. By setting the upper limit of conditional expression (7) to 0.185 or 0.180, the effect of this embodiment can be made more reliable.

[0066] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (8) is satisfied.

[0067] 0.20<ft / TLt<0.50 …(8) Where, ft: focal length of the zoom optical system at the telephoto end TLt: The total length of the zoom optical system at the telephoto end

[0068] Conditional expression (8) is a conditional expression for specifying the ratio of the focal length ft of the variable power optical system in the telephoto end state in the variable power optical system ZL to the total length TLt of the variable power optical system ZL in the telephoto end state and for specifying an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (8), a variable power optical system with high optical performance can be realized while achieving miniaturization.

[0069] When the corresponding value of conditional expression (8) is lower than the lower limit, it becomes difficult to realize a variable magnification optical system with good optical performance while achieving miniaturization. By setting the lower limit of conditional expression (8) to 0.25 or 0.30, the effect of this embodiment can be made more reliable.

[0070] When the corresponding value of conditional expression (8) exceeds the upper limit, it becomes difficult to realize a variable power optical system with good optical performance while achieving miniaturization. By setting the upper limit of conditional expression (8) to 0.45 or 0.40, the effect of this embodiment can be made more reliable.

[0071] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (9) is satisfied.

[0072] 0.70<Mv2 / f2<1.30 …(9) Wherein, Mv2: the movement amount of the second lens group when zooming from the wide-angle end state to the telephoto end state

[0073] Conditional expression (9) is a conditional expression for defining a ratio between the movement amount Mv2 of the second lens group and the focal length f2 of the second lens group when zooming from the wide-angle end state to the telephoto end state, and for defining an appropriate range. In the zoom optical system ZL, by satisfying conditional expression (9), a zoom optical system with good optical performance can be realized while achieving miniaturization.

[0074] When the corresponding value of conditional expression (9) is lower than the lower limit, it becomes difficult to realize a variable magnification optical system with good optical performance while achieving miniaturization. By setting the lower limit of conditional expression (9) to 0.75 or 0.80, the effect of this embodiment can be made more reliable.

[0075] On the other hand, when the corresponding value of conditional expression (9) exceeds the upper limit, correction of spherical aberration, coma and field curvature becomes difficult, which is not preferable. By setting the upper limit of conditional expression (9) to 1.25 or 1.20, the effect of this embodiment can be made more reliable.

[0076] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (10) is satisfied.

[0077] 0.36<Mv3 / (-f3)<0.80…(10) Mv3: The movement amount of the third lens group when zooming from the wide-angle end state to the telephoto end state

[0078] Conditional expression (10) is a conditional expression for defining a ratio between the movement amount Mv3 of the third lens group and the focal length f3 of the third lens group when zooming from the wide-angle end state to the telephoto end state, and defining an appropriate range. When zooming from the wide-angle end state to the telephoto end state, the third lens group moves toward the object side. At this time, in the zoom optical system ZL, by satisfying conditional expression (10), a zoom optical system with good optical performance can be realized while achieving miniaturization.

[0079] When the corresponding value of conditional expression (10) is lower than the lower limit, it becomes difficult to achieve good optical performance while achieving miniaturization. In order to make the effect of conditional expression (10) more reliable, it is preferable to set the lower limit to 0.37 or 0.38.

[0080] On the other hand, when the corresponding value of conditional expression (10) exceeds the upper limit, the power of the third lens group becomes larger, and correction of spherical aberration, coma and image curvature becomes difficult, so it is not preferred. On the other hand, the movement amount Mv3 of the third lens group when zooming becomes larger, and miniaturization of the optical system becomes difficult. In order to make the effect of conditional expression (10) more reliable, it is more preferable to set the upper limit value to 0.70 or 0.60.

[0081] Preferably, the variable magnification optical system has an aperture arranged in the second lens group, and the second lens group has an anti-shake lens group arranged on the image side relative to the aperture. The anti-shake lens group is arranged at a position behind the aperture in the optical system, so that light incident at a strong angle can be cut off, thereby obtaining good anti-shake performance.

[0082] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (11) is satisfied.

[0083] 1.20<fvr / f2<2.20 …(11) Where, fvr: focal length of the anti-shake lens group

[0084] Conditional expression (11) is a conditional expression for defining the ratio of the focal length fvr of the anti-shake lens group to the focal length f2 of the second lens group and defining an appropriate range. In the variable power optical system ZL, by satisfying conditional expression (11), spherical aberration, coma and field curvature can be corrected well.

[0085] When the corresponding value of conditional expression (11) is lower than the lower limit, the optical power of the anti-shake lens group becomes larger, and the correction of spherical aberration, coma and image curvature becomes difficult, so it is not preferred. By setting the lower limit of conditional expression (11) to 1.30 or 1.40, the effect of this embodiment can be made more reliable.

[0086] On the other hand, when the corresponding value of conditional expression (11) exceeds the upper limit, the optical power of the second lens group becomes large, and correction of spherical aberration, coma and field curvature becomes difficult, which is not preferred. By setting the upper limit of conditional expression (11) to 2.10 or 2.00, the effect of this embodiment can be made more reliable.

[0087] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (12) is satisfied.

[0088] 1.00<Mv2 / Mv3<1.80 …(12) Wherein, Mv2: the movement amount of the second lens group when zooming from the wide-angle end state to the telephoto end state Mv3: Movement amount of the third lens group when zooming from the wide-angle end state to the telephoto end state

[0089] Conditional expression (12) is a conditional expression for specifying the ratio of the movement amount Mv2 of the second lens group to the movement amount Mv3 of the third lens group when zooming and for specifying an appropriate range. In the zoom optical system ZL, by satisfying conditional expression (12), a zoom optical system with good optical performance can be realized while achieving miniaturization.

[0090] When the corresponding value of conditional expression (12) is lower than the lower limit, the movement amount Mv2 of the second lens group during zooming becomes smaller, and correction of spherical aberration, coma and image curvature becomes difficult, so it is not preferred. On the other hand, the movement amount Mv3 of the third lens group becomes larger, and miniaturization becomes difficult. In order to make the effect of conditional expression (12) more reliable, it is preferred to set the lower limit value to 1.10 or 1.20.

[0091] On the other hand, when the corresponding value of conditional expression (12) exceeds the upper limit, the movement amount Mv3 of the third lens group during zooming becomes smaller, and correction of spherical aberration, coma and field curvature becomes difficult, so it is not preferred. On the other hand, the movement amount Mv2 of the second lens group becomes larger, and miniaturization becomes difficult. In order to make the effect of conditional expression (12) more reliable, it is preferred to set the upper limit value to 1.75 or 1.70.

[0092] In the above variable power optical system, it is preferred that the third lens group moves on the optical axis to perform focusing from an infinitely distant object to a close object. By performing focusing using the third lens group, it is possible to reduce the change in the angle of view during focusing.

[0093] The above-mentioned zoom optical system preferably moves the second lens group and the third lens group toward the object side when zooming from the wide-angle end state to the telephoto end state, the interval between the first lens group and the second lens group decreases, and the interval between the third lens group and the fourth lens group increases. Thus, a zoom optical system with less center of gravity movement and good optical performance can be realized when zooming from the wide-angle end state to the telephoto end state.

[0094] In the above-mentioned zoom optical system, when zooming, the fourth lens group is preferably fixed relative to the image plane. By fixing the fourth lens group relative to the image plane in addition to fixing the first lens group relative to the image plane when zooming, zooming can be performed while the total length of the zoom optical system remains unchanged, and a zoom optical system with less center of gravity movement and good optical performance can be realized.

[0095] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (13) is satisfied.

[0096] 0.15<Mv2 / TL<0.25 …(13) Wherein, Mv2: the movement amount of the second lens group when zooming from the wide-angle end state to the telephoto end state TL: Total length of the zoom optical system

[0097] Conditional expression (13) is a conditional expression for specifying the ratio of the movement amount Mv2 of the second lens group when zooming and the total length TL of the zoom optical system, and for specifying an appropriate range. The total length TL of the zoom optical system can be the total length of the zoom optical system in the wide-angle end state (TLw) or the total length of the zoom optical system in the telephoto end state (TLt). In the zoom optical system ZL, by satisfying conditional expression (13), a zoom optical system with good optical performance can be realized while achieving miniaturization. In order to make the effect of the embodiment reliable, it is preferable to set the lower limit value of conditional expression (13) to 0.16 or 0.17. In addition, it is preferable to set the upper limit value of conditional expression (13) to, for example, 0.20 or 0.19.

[0098] In the variable power optical system ZL according to the present embodiment, it is preferable that the following conditional expression (14) is satisfied.

[0099] 0.08<Mv3 / TL<0.20 …(14) Mv3: The movement amount of the third lens group when zooming from the wide-angle end state to the telephoto end state TL: Total length of the zoom optical system

[0100] Conditional expression (14) is a conditional expression for specifying the ratio of the movement amount Mv3 of the third lens group when zooming and the total length TL of the zoom optical system, and for specifying an appropriate range. The total length TL of the zoom optical system can be the total length of the zoom optical system in the wide-angle end state (TLw) or the total length of the zoom optical system in the telephoto end state (TLt). In the zoom optical system ZL, by satisfying conditional expression (14), a zoom optical system with high optical performance can be realized while achieving miniaturization. In order to make the effect of this embodiment reliable, it is preferable to set the lower limit value of conditional expression (14) to 0.09 or 0.10. In addition, it is preferable to set the upper limit value of conditional expression (14) to, for example, 0.17 or 0.13.

[0101] Here, refer to Fig. 20 The manufacturing method of the variable power optical system ZL constructed as described above is described. First, a first lens group with negative optical focal length, a second lens group with positive optical focal length, a third lens group with negative optical focal length, and a fourth lens group with positive optical focal length are sequentially arranged along the optical axis from the object side (step ST10), so that when the magnification is changed, the first lens group is fixed relative to the image plane, and the intervals between adjacent lens groups change (step ST20). Then, each lens is arranged in the lens barrel in a manner that at least satisfies conditional expressions (1) and (2) (step ST30). According to such a manufacturing method, a small variable power optical system ZL with good optical performance can be obtained.

[0102] Example

[0103] Hereinafter, a variable power optical system ZL according to an example of the present embodiment will be described with reference to the drawings. Figure 1 , Figure 4 , Figure 7 , Fig.10 , Fig.13 , Fig.16 It is a cross-sectional view showing the structure and optical power distribution of the variable magnification optical system ZL {ZL(1)~ZL(6)} involved in the first to sixth embodiments. In addition, the first to sixth embodiments are embodiments corresponding to the present embodiment, and in each figure, the movement direction of the lens group that moves when the magnification is changed from the wide-angle end state (W) to the telephoto end state (T) along the optical axis is indicated by an arrow. In addition, the lens group that moves when focusing from infinity to a close object is set as the focus lens group GF, and the movement direction is indicated by an arrow together with the word "focus". In addition, at least a part of the second lens group constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image shake on the image plane I) caused by hand shake, etc. As an anti-shake lens group, the movement direction when correcting image shake is indicated by an arrow together with the word "anti-shake".

[0104] In these figures ( Figure 1 , Figure 4 , Figure 7 , Fig.10 , Fig.13 , Fig.16 ), each lens group is represented by a combination of a symbol G and a number, and each lens is represented by a combination of a symbol L and a number. In this case, in order to prevent the types and numbers of symbols and numbers from becoming large and complicated, a combination of symbols and numbers is used independently in each embodiment to represent the lens group, etc. Therefore, even if the same combination of symbols and numbers is used between embodiments, it does not mean that the same structure is used. In addition, the symbol (+) or (-) attached to each lens group number represents the optical power of each lens group, which is the same in all the following embodiments.

[0105] Tables 1 to 6 are shown below, wherein Table 1 is a table showing various parameter data in the first embodiment, Table 2 is a table showing various parameter data in the second embodiment, Table 3 is a table showing various parameter data in the third embodiment, Table 4 is a table showing various parameter data in the fourth embodiment, Table 5 is a table showing various parameter data in the fifth embodiment, and Table 6 is a table showing various parameter data in the sixth embodiment. In each embodiment, the d line (wavelength λ=587.6nm) and the g line (wavelength λ=435.8nm) are selected as the calculation objects of the aberration characteristics.

[0106] In the table of [Overall Parameters], f represents the focal length of the entire optical system, FNO represents the F value, ω represents the half field of view angle (unit: ° (degrees), and Y represents the image height. TL represents the total length of the optical system. Specifically, it represents the distance obtained by adding BF to the distance from the front face of the lens to the rear face of the lens on the optical axis when focusing at infinity. BF represents the air-converted distance from the rear face of the lens to the image plane I on the optical axis when focusing at infinity (back focus). In addition, these values ​​respectively show the values ​​in each zoom state of the wide-angle end (wide), middle focal length (middle), and telephoto end (tele). In addition, in the table of [Overall Parameters], fvr represents the focal length of the anti-shake lens group GVR.

[0107] In the table of [lens parameters], the surface number indicates the order of the optical surfaces from the object side along the direction of light travel, R indicates the radius of curvature of each optical surface (the surface with the center of curvature on the image side is a positive value), D indicates the distance on the optical axis from each optical surface to the next optical surface (or image surface), i.e., the surface interval, and nd indicates the refractive index of the material of the optical component with respect to the d-line. The "∞" of the radius of curvature indicates a plane or an opening, and (aperture S) indicates an aperture stop. The record of the refractive index of air nd=1.00000 is omitted. In the case where the lens surface is an aspherical surface, the surface number is marked with an *, and the paraxial curvature radius is shown in the column of the radius of curvature R.

[0108] In the table of [Aspheric surface data], for the aspheric surface shown in [Lens parameters], its shape is expressed by the following formula (A). X(y) represents the distance along the optical axis from the tangent plane at the vertex of the aspheric surface to the position on the aspheric surface at height y (the amount of concavity), R represents the curvature radius of the reference spherical surface (paraxial curvature radius), κ represents the cone constant, and Ai represents the i-th order aspheric coefficient. "En" represents "×10 -n For example, 1.234E-05=1.234×10 -5 In addition, the second-order aspheric coefficient A2 is 0, and its description is omitted.

[0109] X(y)=(y 2 / R) / {1+(1-κ×y 2 / R 2 ) 1 / 2}+A4×y 4 +A6×y 6 +A8×y 8 +A10×y 10 +A12×y 12 …(A)

[0110] In the table of [Lens Group Data], the focal length of each lens group is shown.

[0111] The table of [Variable Interval Data] shows the surface intervals at the surface numbers where the surface intervals in the table of [Lens Parameters] become "variable". Here, the surface intervals at the wide-angle end (wide), the middle focal length (middle), and the telephoto end (tele) are shown for focusing at infinity and close distance. In [Variable Interval Data], f represents the focal length of the entire optical system.

[0112] The table of [Conditional Expression Corresponding Values] shows the values ​​corresponding to each conditional expression.

[0113] In the following, all parameter values, such as focal length f, radius of curvature R, surface spacing D, and other lengths, are generally expressed in "mm" unless otherwise specified. However, the optical system is not limited to this because the same optical performance can be achieved even if it is scaled up or down.

[0114] The description of the table so far is common to all the embodiments, and repeated description will be omitted below.

[0115] (First embodiment)

[0116] For the first embodiment, use Figure 1 to Figure 3 And Table 1 for explanation. Figure 1 The lens structure diagram of the variable power optical system ZL (ZL(1)) involved in the first embodiment in the wide-angle end state. The variable power optical system ZL(1) involved in the first embodiment is composed of a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, a third lens group G3 with negative optical power, and a fourth lens group G4 with positive optical power, which are arranged in order from the object side along the optical axis.

[0117] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0118] The first lens group G1 includes a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, a biconcave negative lens L13, and a positive meniscus lens L14 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis.

[0119] The second lens group G2 is composed of a biconvex positive lens L21, a meniscus positive lens L22 with a convex surface facing the object side, a biconcave negative lens L23, an aperture stop S, a biconvex positive lens L24, a meniscus negative lens L25 with a convex surface facing the image side, and a meniscus positive lens L26 with a concave surface facing the object side, which are arranged in order from the object side along the optical axis. In addition, the positive lens L24 and the negative lens L25 form a cemented lens in which they are cemented to each other.

[0120] The third lens group G3 is composed of a negative lens L31 having a biconcave shape. The fourth lens group G4 is composed of a positive lens L41 having a convex surface facing the image side. An image surface I is arranged on the image side of the fourth lens group.

[0121] The aperture stop S for the purpose of adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the cemented lens of the positive lens L24 and the negative lens L25 in the second lens group G2 constitutes the anti-shake lens group GVR. In addition, in this embodiment, the third lens group G3 conforms to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0122] Table 1 below shows various parameters in Example 1. In Example 1, the 19th lens surface is formed in an aspherical shape.

[0123] (Table 1)

[0124] [Overall parameters]

[0125] [Lens parameters]

[0126] [Aspherical surface data]

[0127] Page 19 κ=0.0000, A4=-1.66060E-04, A6=2.26257E-06, A8=-2.73958E-07, A10=1.18829E-08 A12=-2.09340E-10

[0128] [Variable interval data]

[0129] [Lens group data] f1 = -15.547 f2 = 16.888 f3 = -19.772 f4 = 44.065

[0130] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0131] Figure 2 , Figure 3 Various aberration diagrams of the variable magnification optical system ZL(1) according to the first embodiment of the present invention. Figure 2 This is a diagram of various aberrations when focusing at infinity at the wide-angle end (f=12.36mm). Figure 3 These are various aberration diagrams when focusing at infinity in the telephoto end state (f=27.16mm). In each aberration diagram, FNO represents the F value, and Y represents the image height. In addition, in each aberration diagram, d represents the aberration under the d-line (λ=587.6nm), and g represents the aberration under the g-line (λ=435.8nm). In addition, in the aberration diagram representing astigmatism, the solid line represents the sagittal image plane, and the dotted line represents the meridional image plane. In addition, in the aberration diagram representing coma, the meridional coma is represented. The above description of the aberration diagram is the same in other embodiments.

[0132] As can be seen from the aberration diagrams, in the first embodiment, each aberration is well corrected in each focal length state from the wide-angle end state to the telephoto end state, and excellent optical performance is achieved. As a result, by installing the variable magnification optical system ZL(1) of the first embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0133] (Second embodiment)

[0134] For the second embodiment, use Figures 4 to 6 And Table 2 for explanation. Figure 4 The lens structure diagram of the variable power optical system ZL (ZL(2)) involved in the second embodiment in the wide-angle end state. The variable power optical system ZL(2) involved in the second embodiment is composed of a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, a third lens group G3 with negative optical power, and a fourth lens group G4 with positive optical power, which are arranged in order from the object side along the optical axis.

[0135] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0136] The first lens group G1 includes a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, a biconcave negative lens L13, and a positive meniscus lens L14 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis.

[0137] The second lens group G2 is composed of a positive lens L21 with a biconvex surface, a positive lens L22 with a meniscus shape whose convex surface faces the object side, an aperture stop S, a negative lens L23 with a meniscus shape whose convex surface faces the object side, a positive lens L24 with a biconvex surface, a positive lens L25 with a biconvex surface, a negative lens L26 with a biconcave surface, and a positive lens L27 with a biconvex surface. The negative lens L23 and the positive lens L24 form a cemented lens bonded to each other. In addition, the positive lens L25 and the negative lens L26 form a cemented lens bonded to each other.

[0138] The third lens group G3 is composed of a negative lens L31 having a biconcave shape. The fourth lens group G4 is composed of a positive lens L41 having a convex surface facing the image side. An image surface I is arranged on the image side of the fourth lens group.

[0139] The aperture stop S for adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the positive lens L25 and the negative lens L26 are joined together, and the positive lens L27 constitute the anti-shake lens group GVR. The lens group G3 corresponds to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0140] The following Table 2 shows various parameters in Example 2. In Example 2, the lens surface of the 23rd surface is formed into an aspherical shape.

[0141] (Table 2)

[0142] [Overall parameters]

[0143] [Lens parameters]

[0144] [Aspherical surface data]

[0145] Page 23 κ=0.0000、A4=7.43737E-05、A6=-3.42988E-07、A8=3.02187E-09、A10=-6.08064E-12、 A12=0.00000E+00

[0146] [Variable interval data]

[0147] [Lens group data] f1 = -13.807 f2 = 15.155 f3 = -15.643 f4 = 43.340

[0148] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0149] Figure 5 , Figure 6 These are the aberration diagrams when the zoom optical system involved in the second embodiment is in the wide-angle end state (f=12.36mm) and the telephoto end state (f=27.16mm) and when focusing at infinity. It can be seen from the aberration diagrams that in the second embodiment, the aberrations are well corrected at each focal length from the wide-angle end state to the telephoto end state, and excellent optical performance is achieved. As a result, by installing the zoom optical system ZL(2) of the second embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0150] (Third embodiment)

[0151] For the third embodiment, use Figure 7 to Figure 9 And Table 3 for explanation. Figure 7This is a lens structure diagram of the variable power optical system ZL (ZL(3)) involved in the third embodiment in the wide-angle end state. The variable power optical system ZL(3) involved in the third embodiment is composed of a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, a third lens group G3 with negative optical power, and a fourth lens group G4 with positive optical power, which are arranged in order from the object side along the optical axis.

[0152] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0153] The first lens group G1 comprises a first positive lens L11 of a meniscus shape with its convex surface facing the object side, a second negative lens L12 of a meniscus shape with its convex surface facing the object side, a third negative lens L13 of a biconcave shape, and a fourth positive lens L14 of a meniscus shape with its convex surface facing the object side, which are arranged in sequence along the optical axis from the object side.

[0154] The second lens group G2 is composed of a positive lens L21 with a meniscus shape with a convex surface facing the object side, a negative lens L22 with a biconcave surface, a positive lens L23 with a biconvex surface, an aperture stop S, a negative lens L24 with a meniscus shape with a convex surface facing the object side, a positive lens L25 with a meniscus shape with a convex surface facing the object side, and a positive lens L26 with a biconvex surface, which are arranged in order from the object side along the optical axis. The negative lens L22 and the positive lens L23 form a cemented lens formed by being cemented to each other. In addition, the negative lens L24 and the positive lens L25 form a cemented lens formed by being cemented to each other.

[0155] The third lens group G3 is composed of a negative lens L31 having a biconcave shape. The fourth lens group G4 is composed of a positive lens L41 having a convex surface facing the image side. An image surface I is arranged on the image side of the fourth lens group.

[0156] The aperture stop S for adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the negative lens L24 and the positive lens L25 in the second lens group G2 are joined to form a cemented lens and a positive lens L26 with a biconvex shape to form an anti-shake lens group GVR. In addition, in this embodiment, the third lens group G3 conforms to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0157] Table 3 below shows various parameters in Example 3. In Example 3, the lens surface of the 21st surface is formed into an aspherical shape.

[0158] (Table 3)

[0159] [Overall parameters]

[0160] [Lens parameters]

[0161] [Aspherical surface data]

[0162] Page 21 κ=0.0000, A4=8.52592E-05, A6=-5.00692E-07, A8=2.15230E-08, A10=-6.18925E-10, A12=6.81140E-12

[0163] [Variable interval data]

[0164] [Lens group data] f1 = -16.310 f2 = 16.086 f3 = -23.133 f4 = 41.888

[0165] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0166] Figure 8 , Fig. 9These are the aberration diagrams when the zoom optical system according to the third embodiment is in the wide-angle end state (f=12.36mm) and the telephoto end state (f=27.16mm) and when focusing at infinity. It can be seen from the aberration diagrams that in the third embodiment, the aberrations are well corrected at each focal length from the wide-angle end state to the telephoto end state, and the lens has excellent optical performance. As a result, by installing the zoom optical system ZL(3) according to the third embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0167] (Fourth embodiment)

[0168] For the fourth embodiment, use Figure 10 to Figure 12 And Table 4 for explanation. Fig.10 This is a lens structure diagram of the variable power optical system ZL (ZL(4)) involved in the fourth embodiment in the wide-angle end state. The variable power optical system ZL(4) involved in the fourth embodiment is composed of a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, a third lens group G3 with negative optical power, and a fourth lens group G4 with positive optical power, which are arranged in order from the object side along the optical axis.

[0169] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0170] The first lens group G1 includes a positive meniscus lens L11 with a convex surface facing the object side, a negative meniscus lens L12 with a convex surface facing the object side, a biconcave negative lens L13, and a positive meniscus lens L14 with a convex surface facing the object side, which are arranged in order from the object side along the optical axis.

[0171] The second lens group G2 is composed of a biconvex positive lens L21, a meniscus positive lens L22 with a convex surface facing the object side, a meniscus negative lens L23 with a convex surface facing the image side, an aperture stop S, a biconvex positive lens L24, a meniscus negative lens L25 with a convex surface facing the image side, and a meniscus positive lens L26 with a convex surface facing the image side, which are arranged in order from the object side along the optical axis. The positive lens L24 and the negative lens L25 form a cemented lens cemented to each other.

[0172] The third lens group G3 is composed of a negative lens L31 having a biconcave shape. The fourth lens group G4 is composed of a positive lens L41 having a convex surface facing the image side. An image surface I is arranged on the image side of the fourth lens group.

[0173] The aperture stop S for adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the positive lens L24 and the negative lens L25 in the second lens group G2 are bonded to form a cemented lens to form an anti-shake lens group GVR. In addition, in this embodiment, the third lens group G3 conforms to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0174] Table 4 below shows various parameters in Example 4. In Example 4, the 19th lens surface is formed in an aspherical shape.

[0175] (Table 4)

[0176] [Overall parameters]

[0177] [Lens parameters]

[0178] [Aspherical surface data]

[0179] Page 19 κ=0.0000, A4=-1.16050E-04, A6=1.68584E-06, A8=-1.57438E-07, A10=5.49231E-09, A12=-7.64340E-11

[0180] [Variable interval data]

[0181] [Lens group data] f1 = -16.135 f2 = 16.958 f3 = -20.165 f4= 39.149

[0182] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0183] Fig.11 , Fig.12 These are the aberration diagrams when the zoom optical system according to the fourth embodiment is in the wide-angle end state (f=12.36mm) and the telephoto end state (f=27.16mm) and when focusing at infinity. It can be seen from the aberration diagrams that in the fourth embodiment, the aberrations are well corrected at each focal length from the wide-angle end state to the telephoto end state, and the lens has excellent optical performance. As a result, by installing the zoom optical system ZL(4) according to the fourth embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0184] (Fifth embodiment)

[0185] For the fifth embodiment, use Figure 13 to Figure 15 And Table 5 for explanation. Fig.13 This is a lens structure diagram of the variable power optical system ZL (ZL(5)) involved in the fifth embodiment in the wide-angle end state. The variable power optical system ZL(5) involved in the fifth embodiment is composed of a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, a third lens group G3 with negative optical power, and a fourth lens group G4 with positive optical power, which are arranged in order from the object side along the optical axis.

[0186] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0187] The first lens group G1 is composed of a negative lens L11 with a convex surface facing the object side, a negative lens L12 with a convex surface facing the object side, and a positive lens L13 with a convex surface facing the object side, which are arranged in sequence from the object side along the optical axis. The negative lens L11 is a hybrid lens in which a resin layer is provided on the image side of a glass lens body. The surface on the image side of the resin layer is an aspherical surface, and the negative lens L11 is a composite aspherical lens. In the [lens parameters] described later, surface number 1 represents the surface on the object side of the lens body, surface number 2 represents the surface on the image side of the lens body and the surface on the object side of the resin layer (the surface where the two are joined), and surface number 3 represents the surface on the image side of the resin layer.

[0188] The second lens group G2 is composed of a positive lens L21 with a biconvex surface, a negative lens L22 with a meniscus shape whose convex surface faces the object side, a positive lens L23 with a biconvex surface, an aperture stop S, a negative lens L24 with a meniscus shape whose convex surface faces the object side, a positive lens L25 with a biconvex surface, and a positive lens L26 with a biconvex surface, which are arranged in order from the object side along the optical axis. The negative lens L22 and the positive lens L23 form a cemented lens formed by being cemented together. In addition, the negative lens L24 and the positive lens L25 form a cemented lens formed by being cemented together.

[0189] The third lens group G3 is composed of a negative meniscus lens L31 with a convex surface facing the object side. The fourth lens group G4 is composed of a positive lens L41 with a convex surface facing the image side. An image surface I is arranged on the image side of the fourth lens group.

[0190] The aperture stop S for adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the negative lens L24 and the positive lens L25 in the second lens group G2 are joined to form a cemented lens and the positive lens L26 to form an anti-shake lens group GVR. In addition, in this embodiment, the third lens group G3 conforms to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0191] Table 5 below shows various parameters in Example 5. In Example 5, each of the lens surfaces, namely the third surface, the eighth surface, and the nineteenth surface, is formed into an aspherical shape.

[0192] (Table 5)

[0193] [Overall parameters]

[0194] [Lens parameters]

[0195] [Aspherical surface data]

[0196] Page 3 κ=-1.0000, A4=4.57524E-05, A6=5.67822E-08, A8=-2.71480E-10, A10=6.14646E-12, A12=-2.71780E-14

[0197] Page 8 κ=0.0000、A4=-3.57723E-05、A6=-1.06964E-07、A8=8.50140E-11、A10=-3.35939E-11、 A12=0.00000E+00

[0198] Page 19 κ=0.0000, A4=-6.87936E-05, A6=6.63289E-07, A8=-1.73689E-08, A10=2.31023E-10, A12=0.00000E+00

[0199] [Variable interval data]

[0200] [Lens group data] f1 = -15.485 f2 = 17.203 f3 = -25.560 f4 = 55.265

[0201] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0202] Fig.14 , 15 These are the aberration diagrams of the zoom optical system according to the fifth embodiment when focusing at infinity in the wide-angle end state (f=10.31mm) and the telephoto end state (f=27.16mm). It can be seen from the aberration diagrams that in the fifth embodiment, the aberrations are well corrected at each focal length from the wide-angle end state to the telephoto end state, and the lens has excellent optical performance. As a result, by installing the zoom optical system ZL(5) according to the fifth embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0203] (Sixth embodiment)

[0204] For the sixth embodiment, use Figure 16 to Figure 18 and Table 6 for illustration. Fig.18The figure is a lens structure diagram of the variable power optical system ZL (ZL(6)) according to the sixth embodiment in the wide-angle end state. The variable power optical system ZL(6) according to the sixth embodiment comprises a first lens group G1 having a negative optical focal length, a second lens group G2 having a positive optical focal length, a third lens group G3 having a negative optical focal length, and a fourth lens group G4 having a positive optical focal length, which are arranged in order from the object side along the optical axis.

[0205] When changing the magnification (zooming) from the wide-angle end state to the telephoto end state, the second lens group G2 and the third lens group G3 move on the optical axis in different orbits in a manner such that the interval between the first lens group G1 and the second lens group G2 is reduced, and the interval between the third lens group G3 and the fourth lens group G4 is increased. In more detail, when changing the magnification, the second lens group G2 moves monotonically along the optical axis toward the object side, the third lens group G3 moves monotonically along the optical axis toward the object side, and the first lens group G1 and the fourth lens group G4 are fixed.

[0206] The first lens group G1 is composed of a negative lens L11 with a meniscus shape whose convex surface faces the object side, a negative lens L12 with a biconcave surface, and a positive lens L13 with a meniscus shape whose convex surface faces the object side, which are arranged in sequence from the object side along the optical axis. The negative lens L11 is a hybrid lens in which a resin layer is provided on the image side of a lens body made of glass. The surface on the image side of the resin layer is an aspherical surface, and the negative lens L11 is a composite aspherical lens. In the [lens parameters] described later, surface number 1 represents the surface on the object side of the lens body, surface number 2 represents the surface on the image side of the lens body and the surface on the object side of the resin layer (the surface where the two are bonded), and surface number 3 represents the surface on the image side of the resin layer.

[0207] The second lens group G2 is composed of a positive lens L21 with a convex surface facing the object side, a negative lens L22 with a convex surface facing the object side, a positive lens L23 with a convex surface facing the object side, an aperture stop S, a negative lens L24 with a convex surface facing the object side, a positive lens L25 with a biconvex surface, and a negative lens L26 with a convex surface facing the object side. The negative lens L22 and the positive lens L23 form a cemented lens bonded to each other. In addition, the negative lens L24 and the positive lens L25 form a cemented lens bonded to each other.

[0208] The third lens group G3 is composed of a negative lens L31 with a biconcave shape. The fourth lens group G4 is composed of a positive lens L41 with a convex surface facing the image side. An image plane I is arranged on the image side of the fourth lens group. The negative lens L31 is a hybrid lens formed by providing a resin layer on the image side of a glass lens body. The surface on the image side of the resin layer is an aspherical surface, and the negative lens L31 is a composite aspherical lens. In the [lens parameters] described later, surface number 19 represents the surface on the object side of the lens body, surface number 20 represents the surface on the image side of the lens body and the surface on the object side of the resin layer (the surface where the two are joined), and surface number 21 represents the surface on the image side of the resin layer.

[0209] The aperture stop S for adjusting the amount of light is arranged in the second lens group, and moves in the same orbit as the second lens group G2 when changing the magnification (zooming) from the wide-angle end state to the telephoto end state. In addition, the lens arranged on the image plane side compared to the aperture stop S in the second lens group G2 constitutes an anti-shake lens group GVR that can move in a direction perpendicular to the optical axis to correct the displacement of the imaging position (image jitter on the image plane I) caused by hand shaking, etc. In this embodiment, the negative lens L24 and the positive lens L25 in the second lens group G2 are joined to form a cemented lens and a negative lens L26 to form an anti-shake lens group GVR. In addition, in this embodiment, the third lens group G3 conforms to the focus lens group GF that moves along the optical axis. When focusing from an object at infinity to an object at a close distance, the focus lens group GF moves along the optical axis toward the image plane side.

[0210] Table 6 below shows various parameters in Example 6. In Example 6, each lens surface, namely, the third surface, the seventeenth surface, the eighteenth surface, and the twenty-first surface, is formed into an aspherical shape.

[0211] (Table 6)

[0212] [Overall parameters]

[0213] [Lens parameters]

[0214] [Aspherical surface data]

[0215] Page 3 κ=-1.0000、A4=7.27375E-05、A6=2.49679E-07、A8=-7.82392E-10、A10=1.38206E-11、 A12=0.00000E+00

[0216] Page 17 κ=0.0000、A4=7.95506E-04、A6=1.55427E-05、A8=-1.72626E-07、A10=1.40171E-09、 A12=0.00000E+00

[0217] Page 18 κ=0.0000, A4=8.39877E-04, A6=1.62508E-05, A8=2.44509E-08, A10=1.12099E-09, A12=0.00000E+00

[0218] Page 21 κ=0.00000、A4=1.79600E-04、A6=-9.82060E-07、A8=1.72937E-09、A10=-2.07534E-10、 A12=0.00000E+00

[0219] [Variable interval data]

[0220] [Lens group data] f1=-17.835 f2=14.885 f3=-18.997 f4=39.529

[0221] It can be seen from this that in this embodiment, all of the above conditional expressions (1) to (14) are satisfied.

[0222] Fig.17 , 18 These are the aberration diagrams of the variable power optical system according to the sixth embodiment when focusing at infinity in the wide-angle end state (f=12.36mm) and the telephoto end state (f=27.16mm). It can be seen from the aberration diagrams that in the sixth embodiment, the aberrations are well corrected at each focal length from the wide-angle end state to the telephoto end state, and the lens has excellent optical performance. As a result, by installing the variable power optical system ZL(6) according to the sixth embodiment, excellent optical performance can be ensured in optical equipment such as cameras.

[0223] Next, a table of [conditional expression corresponding values] is shown below. In this table, values ​​corresponding to the conditional expressions (1) to (14) are collectively shown for all the examples (first to sixth examples).

[0224] Conditional formula (1) 0.70<(-f1) / f2<1.30

[0225] Conditional formula (2) 0.55<f2 / (-f3)<1.20

[0226] Conditional formula (3) 0.20<(-f1) / f4<0.50

[0227] Conditional formula (4) 0.20<(-f3) / f4<0.90

[0228] Conditional formula (5) 0.50<f1 / f3<1.10

[0229] Conditional formula (6) 0.20<f2 / f4<0.70

[0230] Conditional formula (7) 0.120<fw / TLw<0.190

[0231] Conditional formula (8) 0.20<ft / TLt<0.50

[0232] Conditional formula (9) 0.70<Mv2 / f2<1.30

[0233] Conditional formula (10) 0.36<Mv3 / (-f3)<0.80

[0234] Conditional formula (11) 1.20<fvr / f2<2.20

[0235] Conditional formula (12) 1.00<Mv2 / Mv3<1.80

[0236] Conditional formula (13) 0.15<Mv2 / TL<0.25

[0237] Conditional formula (14) 0.08<Mv3 / TL<0.20

[0238] [Conditional Expression Corresponding Value] (1st to 6th Embodiments)

[0239] As described above, according to each embodiment, a variable magnification optical system and an optical device having good optical performance can be realized while achieving miniaturization.

[0240] In addition, in the above-mentioned embodiment, the contents described below can be appropriately adopted within a range that does not impair the optical performance.

[0241] In the above-mentioned embodiments, a 4-group structure is shown as a variable-power optical system, but it can also be applied to other group structures such as 5 groups. In addition, it can also be a structure in which a lens or a lens group is added to the side closest to the object, or a structure in which a lens or a lens group is added to the side closest to the image. In addition, a lens group means a part having at least one lens separated by an air space that changes when the power is changed.

[0242] In addition, a single lens group or a plurality of lens groups, or a part of the lens group, can be used as a focus lens group that moves along the optical axis to focus from an infinitely distant object to a close-up object. The focus lens group can also be applied to autofocus and is also suitable for motor drive (using an ultrasonic motor, etc.) for autofocus.

[0243] In the variable power optical system of each embodiment, the lens is not limited to being a part of the second lens group, but may also be an anti-shake lens group that corrects image shake caused by hand shake by moving the lens group or part of the lens group in a manner having a component in a direction perpendicular to the optical axis, or by rotationally moving (swinging) in a plane direction including the optical axis.

[0244] The lens surface may be formed by a spherical surface or a flat surface, or may be formed by an aspherical surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment become easy, and degradation of optical performance caused by errors in processing and assembly adjustment can be prevented, so it is preferred. In addition, even in the case of deviation of the image plane, degradation of the image rendering performance is small, so it is preferred.

[0245] When the lens surface is an aspheric surface, the aspheric surface may be any of an aspheric surface based on grinding, a glass molded aspheric surface formed by a mold into an aspheric shape of glass, and a composite aspheric surface formed by a resin on the surface of glass into an aspheric shape. In addition, the lens surface may be a diffraction surface, or the lens may be a distributed refractive index lens (GRIN lens) or a plastic lens.

[0246] In addition, the aperture stop is preferably arranged in the second lens group, but a member serving as the aperture stop may not be provided and the lens frame may be used instead to perform its function.

[0247] In order to reduce glare and ghosting and achieve high optical performance with high contrast, an anti-reflection film with high transmittance in a wide wavelength range may be applied to each lens surface.

[0248] Furthermore, although the variable power optical system of this embodiment is used in a camera, the system is not limited thereto and may be used in optical equipment such as a camera having a moving image shooting function, for example.

[0249] Description of symbols ZL zoom optical system G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group S Aperture stop I Image plane

Claims

1. A variable power optical system comprising a first lens group having negative optical power, a second lens group having positive optical power, a third lens group having negative optical power, and a fourth lens group having positive optical power, which are arranged in order from the object side along the optical axis, wherein: When zooming, the first lens group is fixed relative to the image plane, and the intervals between adjacent lens groups change. The variable magnification optical system satisfies the following conditional formula: 0.70<(-f1) / f2<1.30 0.55<f2 / (-f3)<1.20 Wherein, f1: the focal length of the first lens group, f2: focal length of the second lens group, f3: focal length of the third lens group.

2. The variable magnification optical system according to claim 1, wherein: The variable magnification optical system satisfies the following conditional formula: 0.20<(-f1) / f4<0.50 Wherein, f4: the focal length of the fourth lens group.

3. The variable magnification optical system according to claim 1 or 2, wherein: The variable magnification optical system satisfies the following conditional formula: 0.20<(-f3) / f4<0.90 Wherein, f4: the focal length of the fourth lens group.

4. The variable power optical system according to any one of claims 1 to 3, wherein: The variable magnification optical system satisfies the following conditional formula: 0.50<f1 / f3<1.

10.

5. The variable power optical system according to any one of claims 1 to 4, wherein: The variable magnification optical system satisfies the following conditional formula: 0.20<f2 / f4<0.70 Wherein, f4: the focal length of the fourth lens group.

6. The variable power optical system according to any one of claims 1 to 5, wherein: The variable magnification optical system satisfies the following conditional formula: 0.120<fw / TLw<0.190 Wherein, fw: focal length of the variable magnification optical system in the wide-angle end state, TLw: The total length of the variable power optical system in the wide-angle end state.

7. The variable power optical system according to any one of claims 1 to 6, wherein: The variable magnification optical system satisfies the following conditional formula: 0.20<ft / TLt<0.50 Wherein, ft is the focal length of the variable magnification optical system in the telephoto end state, TLt: The total length of the variable magnification optical system in the telephoto end state.

8. The variable power optical system according to any one of claims 1 to 7, wherein: The variable magnification optical system satisfies the following conditional formula: 0.70<Mv2 / f2<1.30 Here, Mv2 is the amount of movement of the second lens group when zooming from the wide-angle end state to the telephoto end state.

9. The variable power optical system according to any one of claims 1 to 8, wherein: The variable magnification optical system satisfies the following conditional formula: 0.36<Mv3 / (-f3)<0.80 Here, Mv3 is the movement amount of the third lens group when zooming from the wide-angle end state to the telephoto end state.

10. The variable power optical system according to any one of claims 1 to 9, wherein: The variable power optical system has an aperture arranged in the second lens group. The second lens group includes an anti-shake lens group disposed on the image plane side relative to the aperture.

11. The variable power optical system according to claim 10, wherein: The variable magnification optical system satisfies the following conditional formula: 1.20<fvr / f2<2.20 Wherein, fvr: the focal length of the anti-shake lens group.

12. The variable power optical system according to any one of claims 1 to 11, wherein: The variable magnification optical system satisfies the following conditional formula: 1.00<Mv2 / Mv3<1.80 Wherein, Mv2: the movement amount of the second lens group when changing the magnification from the wide-angle end state to the telephoto end state, Mv3: The amount of movement of the third lens group when zooming from the wide-angle end state to the telephoto end state.

13. The variable power optical system according to any one of claims 1 to 12, wherein: The third lens group moves on the optical axis to achieve focusing from an object at infinity to an object at a short distance.

14. The variable power optical system according to any one of claims 1 to 13, wherein: When changing the magnification from the wide-angle end state to the telephoto end state, the second lens group and the third lens group move toward the object side, the distance between the first lens group and the second lens group decreases, and the distance between the third lens group and the fourth lens group increases.

15. The variable power optical system according to any one of claims 1 to 14, wherein: When changing magnification, the fourth lens group is fixed relative to the image plane.

16. The variable power optical system according to any one of claims 1 to 15, wherein: The variable magnification optical system satisfies the following conditional formula: 0.15<Mv2 / TL<0.25 Wherein, Mv2: the movement amount of the second lens group when changing the magnification from the wide-angle end state to the telephoto end state, TL: The total length of the variable magnification optical system.

17. The variable power optical system according to any one of claims 1 to 16, wherein: The variable magnification optical system satisfies the following conditional formula: 0.08<Mv3 / TL<0.20 Wherein, Mv3: the movement amount of the third lens group when changing the magnification from the wide-angle end state to the telephoto end state, TL: The total length of the variable magnification optical system.

18. An optical device comprising the variable power optical system according to any one of claims 1 to 17.

19. A method for manufacturing a variable power optical system, the variable power optical system comprising a first lens group with negative optical power, a second lens group with positive optical power, a third lens group with negative optical power, and a fourth lens group with positive optical power arranged in sequence from the object side along an optical axis, wherein: When zooming, the first lens group is fixed relative to the image plane, and the intervals between adjacent lens groups change. The method for manufacturing the variable magnification optical system comprises the steps of arranging each lens in the lens barrel in a manner satisfying the following conditional expression: 0.70<(-f1) / f2<1.30 0.55<f2 / (-f3)<1.20 Wherein, f1: the focal length of the first lens group, f2: focal length of the second lens group, f3: focal length of the third lens group.

Images