JP2016071282A - Variable magnification optical system, imaging device, and manufacturing method of variable magnification optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable magnification optical system, imaging device, and manufacturing method of the variable magnification optical system that allow even a simple configuration to implement a variable magnification and focusing in either state of a land photography and underwater photography, and have an excellent performance.SOLUTION: An amphibious variable magnification lens device 10 capable of photography under water and on a land has, arranged in order from an object side along an optical axis,: a first lens group G1; and at least three movement lens groups (for example, second lens group G2 to fourth lens group G4), in which the first lens group G1 is made stationary, movement of the movement lens group implements the variable magnification, and in a land photography and underwater photography, mutually different movement lens groups (for example, the second lens group G2 in a state of the underwater photography and the third lens group G3 in a state of the land photography) are caused to move along the optical axis, and thereby, focusing is implemented.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a variable magnification optical system, an imaging apparatus, and a method for manufacturing the variable magnification optical system.

Conventionally, amphibious variable power lens devices have been proposed (see, for example, Patent Documents 1 and 2).

JP-A-7-159687 Japanese Patent Laid-Open No. 7-159589

However, the conventional amphibious variable magnification lens device is not convenient because it cannot be changed in the underwater shooting state or an auxiliary lens system needs to be attached. In both the land shooting state and the underwater shooting state, none has good optical performance over the entire shooting distance from a long distance to a short distance.

In order to solve such problems, the variable magnification optical system according to the present invention is a variable magnification optical system that can be used in water and on land, and is arranged in order from the object side along the optical axis. A lens group and at least three lens groups, the position of the first lens group on the optical axis is fixed, and at least one of the three lens groups is moved along the optical axis. And performing focusing in water by moving at least part of the three lens groups along the optical axis as a first focusing lens group, and at least part of the three lens groups is second Land focusing is performed by moving the focusing lens group along the optical axis, and the first focusing lens group and the second focusing lens group are different in at least one of configuration and movement locus.

  An imaging apparatus according to the present invention includes the above-described variable magnification optical system.

A method of manufacturing a variable magnification optical system according to the present invention is a method of manufacturing a variable magnification optical system that can be used in water and on land, and is arranged in order from the object side along the optical axis; , At least 3
The first lens group is fixed on the optical axis, and at least one of the three lens groups is moved along the optical axis to perform zooming. At least a part of the three lens groups is moved along the optical axis as a first focusing lens group to perform focusing in water, and at least a part of the three lens groups is used as a second focusing lens group. Focusing on land by moving along an axis, the first focusing lens group and the second focusing lens group are arranged in the housing so that at least one of the configuration and the movement locus is different. Place the lens.

It is a section lineblock diagram of the amphibious variable magnification lens device concerning a 1st embodiment. It is a figure which shows the transmission relationship of the information and control of the amphibious variable magnification lens apparatus which concerns on 1st Embodiment. It is sectional drawing which shows the lens structure of the amphibious variable magnification lens apparatus which concerns on 1st Embodiment, and the figure which shows the movement locus | trajectory of each group from a wide-angle end state to a telephoto end state. FIG. 4A is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the first embodiment in an infinite focus state in a land photographing state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c). Indicates the telephoto end state. FIG. 4 is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the first embodiment in an infinite focus state in an underwater shooting state, in which (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c). Indicates the telephoto end state. FIG. 3A is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the first embodiment in a short-distance in-focus state with an object-to-image distance of 300 mm in a land-photographed state, in which FIG. The distance state, (c) shows the telephoto end state. FIG. 3A is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the first embodiment in a short-distance in-focus state with an object-to-image distance of 300 mm in an underwater shooting state, where FIG. The distance state, (c) shows the telephoto end state. It is a section lineblock diagram of the amphibious variable magnification lens device concerning a 2nd embodiment. It is a figure which shows the transmission relationship of the information and control of the amphibious variable magnification lens apparatus which concerns on 2nd Embodiment. It is sectional drawing which shows the lens structure of the amphibious variable magnification lens apparatus which concerns on 2nd Embodiment, and the figure which shows the movement locus | trajectory of each group from a wide-angle end state to a telephoto end state. FIG. 9 is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the second embodiment in an infinite focus state in a land photographing state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c). Indicates the telephoto end state. FIG. 6 is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the second embodiment in an infinite focus state in an underwater shooting state, where (a) is a wide-angle end state, (b) is an intermediate focal length state, and (c). Indicates the telephoto end state. FIG. 9 is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the second embodiment in a short-distance focusing state with an object-to-image distance of 300 mm in a land photographing state. The distance state, (c) shows the telephoto end state. FIG. 9 is a diagram illustrating various aberrations of the amphibious variable magnification lens apparatus according to the second embodiment in a close-up state with an object-to-image distance of 300 mm in an underwater shooting state, in which (a) is a wide-angle end state and (b) is an intermediate focus. The distance state, (c) shows the telephoto end state. It is a figure which shows the structure of the camera provided with the amphibious variable magnification lens apparatus which concerns on this embodiment. It is a flowchart which shows the manufacturing method of the amphibious variable magnification lens apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the characteristic configuration of the optical system common to each embodiment according to the present invention will be described. Next, a first embodiment according to the present invention will be described with reference to FIGS. With reference to FIGS.
A second embodiment according to the present invention will be described. The imaging apparatus according to these embodiments will be described with reference to FIG. The manufacturing method according to these embodiments will be described with reference to FIG.

A characteristic configuration of the optical system ZL common to the amphibious variable magnification lens apparatuses 10 and 100 according to the present embodiment will be described (see FIGS. 3 and 10). 3 and 10, the movement trajectory of the lens group in the land shooting state is indicated by a solid line, and the movement trajectory of the lens group in the underwater shooting state is indicated by a dotted line.

The amphibious zoom lens devices 10 and 100 are capable of photographing underwater and on land, and are arranged in order from the object side along the optical axis, and a first lens group G1 and at least three moving lens groups (
For example, it has a second lens group G2, a third lens group G3, and a fourth lens group G4). The first lens group G1 is fixed, and the moving lens group is moved along the optical axis to change the magnification. And
The moving lens groups that are different in the land photographing state and the underwater photographing state (for example, the third lens group G3 (corresponding to the second focusing lens group in the claims) in the land photographing state, and the second lens group in the underwater photographing state) An optical system ZL configured to perform focusing by moving G2 (corresponding to the first focusing lens group in claims) along the optical axis is mounted.

In the optical system ZL, the first lens group G1 is fixed to ensure airtightness in the underwater shooting state. By carrying at least three moving lens groups that move the zooming action,
Scaling can be done efficiently. This configuration is advantageous for downsizing the optical system. For focusing, by moving the moving lens groups that are different in the land shooting state and underwater shooting state along the optical axis, it is possible to select the optimum focusing group according to the shooting state, In both the land photographing state and the underwater photographing state, it is possible to suppress the change in the imaging position while correcting particularly the field curvature and astigmatism.

The optical system ZL according to the present embodiment performs focusing by moving the moving lens group (for example, the second lens group G2) having the negative refractive power located closest to the object side in the underwater shooting state, In the land photographing state, it is preferable to perform focusing by moving the moving lens group (for example, the third lens group G3) located second from the object side.

Thus, by adopting different focusing methods for the land photographing state and the underwater photographing state, it is possible to satisfactorily correct the fluctuation of the field curvature at the time of focusing in both the land photographing state and the underwater photographing state. In particular, in the present embodiment, when switching from the land photographing state to the underwater photographing state, the second lens group G2 and the third lens group G3 are moved in the image plane direction to switch the underwater photographing state as in the examples described later. Since the second lens group G2 and the third lens group G3 are moved in the object direction at the time of switching from the land photography state to the land photography state, the third lens group G3 and the fourth lens group G4 are constructed in the land photography state. And the first lens group G1 in the underwater shooting state.
And the second lens group G2 are relatively wide. In other words, since focusing is performed using a gap that is relatively wide according to the shooting state, it is possible to sufficiently achieve focusing to a close object while keeping the entire length of the optical system ZL small. it can.

The optical system ZL according to the present embodiment has at least two lens groups (for example, the second lens group G2) among the moving lens groups when the shooting state changes between the land shooting state and the underwater shooting state. And the third lens group G3) are preferably moved in a predetermined direction along the optical axis. It should be noted that it is more preferable to move the second lens group G2 and the third lens group G3 along the optical axis in the image plane direction when the land shooting state is changed to the underwater shooting state. In addition, when the underwater shooting state changes to the land shooting state, it is more preferable to move the second lens group G2 and the third lens group G3 along the optical axis in the object direction.

With this configuration, it is possible to simultaneously perform correction of the focal position and correction of various aberrations including field curvature and distortion in both the land photographing state and the underwater photographing state.

The optical system ZL according to this embodiment includes a first lens group G1 having a positive or negative refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power, which are arranged in order from the object side. A third lens group G3, and a fourth lens group G4 having a positive refractive power.
It is preferable to perform zooming by changing the air gap between the lens group G2 and the air gap between the second lens group G2 and the third lens group G3. The air gap between the third lens group G3 and the fourth lens group G4 may be constant or may be changed.

With this configuration, zooming can be performed efficiently, and it is advantageous for downsizing and widening the optical system ZL.

In the optical system ZL according to the present embodiment, the first lens group G1 is preferably formed of a meniscus lens having a convex surface facing the object side. With this configuration, it is possible to suppress changes in the angle of view when placed in water and to suppress the occurrence of distortion, lateral chromatic aberration, curvature of field, and the like.

In the optical system ZL according to the present embodiment, the lens located closest to the object side of the second lens group G2 is
A negative meniscus lens having a concave surface facing the image surface side is preferable. With this configuration, various aberrations such as spherical aberration and distortion can be corrected satisfactorily.

In the optical system ZL according to the present embodiment, it is preferable that the third lens group G3 is composed of a biconvex positive lens. With this configuration, the lens configuration can be simplified, downsized, and reduced in cost.

In the optical system ZL according to the present embodiment, the first focusing lens group or the second focusing lens group may be configured by one lens group, or may be configured by a plurality of lens groups. Further, it may be a part of the lens group and may be composed of one or more lenses.

In the optical system ZL according to the present embodiment, the first focusing lens group and the second focusing lens group may have completely different configurations, or may have a partially different configuration (for example, the first focusing lens group). A part of the focusing lens group may be the second focusing lens group, or a part of the second focusing lens group may be the first focusing lens group). Just be fine.

The optical system ZL according to the present embodiment has a configuration in which the first focusing lens group and the second focusing lens group may have different movement trajectories, may have different movement directions, and have the same movement trajectory. Just different.

In the optical system ZL according to the present embodiment, the first lens group G1 may be a protective glass having no refractive power or a protective glass having a low refractive power.

An amphibious variable power lens apparatus 10 according to this embodiment, which is equipped with the optical system ZL having the above-described configuration,
According to No. 100, although it is a simple configuration, zooming and focusing can be performed in both the land photographing state and the underwater photographing state, and excellent optical performance can be achieved.

(First embodiment)
The amphibious variable power lens apparatus 10 according to the first embodiment will be described. As shown in FIG. 1, the amphibious variable magnification lens apparatus 10 of the first embodiment is arranged in order from the object side in the housing 1.
An optical system ZL (ZL1) including a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. ).

The first lens group G1 is fixed on the optical axis via the first lens group fixing portion 1a to the housing 1, and the second lens group G2, the third lens group G3, and the fourth lens group G4 are optical It is hold | maintained by the member mentioned later in the housing | casing 1 so that each movement along an axis | shaft is possible.

A mount member 11 is fixed to the image side end 1b of the housing 1, and the amphibious variable power lens device 10 is fixed to an imaging device described later by the mount member 11.

2nd lens group G2 is hold | maintained at the 2nd lens group lens frame 2, and this lens frame 2 is supported by the 1st support member 21 arrange | positioned in the housing | casing 1 so that sliding is possible, and the control shown in FIG. Based on a control signal from the unit 71, the first drive mechanism 22 is configured to move along the optical axis.

The fourth lens group G4 is held by the fourth lens group lens frame 4, and the pins 4a extending in the radial direction from the lens frame 4 change the focal length through the long hole 5 opened in the housing 1. Is engaged with a cam groove 6a formed in the operation member 6. When the operating member 6 is rotated, the pin 4a moves along the cam groove 6a formed on the inner wall of the operating member 6, whereby the fourth lens group G4 moves along the optical axis.

The operation member 6 is connected to a focal length detection unit 51 disposed in the housing 1 via an interlocking member 51a. When the operation member 6 is operated, the focal length detection unit 51 detects a focal length change request via the interlocking member 51 a and outputs a focal length value corresponding to the rotation amount of the operation member 6.

A rubber ring (not shown) is sandwiched between the sliding portion between the operation member 6 and the housing 1 to prevent water from entering during underwater photography.

A switch member 42 for switching between a land shooting state and an underwater shooting state is provided outside the housing 1. A shooting state identification unit 41 that identifies the shooting state changed by the switch member 42 is disposed in the housing 1. In the present embodiment, the switch member 42 switches between the land shooting state and the underwater shooting state, and the shooting state identifying unit 41 identifies the shooting state. However, the switch member 42 is not provided, and the land shooting state is detected by a sensor or the like. Or the underwater shooting state may be automatically identified.

The third lens group G3 is held by the third lens group lens frame 3, and this lens frame 3 is slidably supported by a second support member 31 arranged fixed to the fourth lens group frame 4, The second lens group G4 is moved in accordance with the movement of the fourth lens group G4, and is further moved along the optical axis by the second drive mechanism 32 based on a control signal from the control unit 71 shown in FIG. .

The amphibious variable magnification lens apparatus 10 according to the first embodiment is on the optical axis of the second lens group G2 and the third lens group G3 set for each focal length in each of the land photographing state and the underwater photographing state. The position information is stored in the storage unit 61 shown in FIG. Second of focal length not memorized
The position information of the lens group G2 and the third lens group G3 can be set by the control unit 71 performing an interpolation process or the like based on the stored position information.

  Thus, the amphibious variable power lens apparatus 10 according to the first embodiment is configured.

In the amphibious variable magnification lens apparatus 10 according to the first embodiment, as shown in FIG. 2, the shooting state identified by the shooting state identification unit 41 by operating the switch member 42 is transmitted to the control unit 71. The Further, the focal length detected by the focal length detection unit 51 by operating the operation member 6 is transmitted to the control unit 71.

The control unit 71 reads position information on the optical axis of the second lens group G2 and the third lens group G3 corresponding to the transmitted shooting state and focal length from the storage unit 61, and via the first drive mechanism 22. Then, the second lens group G2 and the third lens group G3 are independently moved to a predetermined optical axis position via the second drive mechanism 32.

At the time of focusing, the control unit 71 moves the second lens group G2 via the first drive mechanism 22 according to the shooting state identified by the shooting state identification unit 41 and in the underwater shooting state. In the land shooting state, the control unit 71 moves the third lens group G3 via the second drive mechanism 32 to perform focusing.

Further, when the switch member 42 is operated and the shooting state identified by the shooting state identification unit 41 is changed, the control unit 71 refers to the storage unit 61 and performs the second operation via the first drive mechanism 22. The lens group G2 is moved, and the third lens group G3 is moved via the second drive mechanism 32 to correct the change in the field curvature and the change in the imaging position due to the change in the photographing state. More specifically, when the land shooting state is changed to the underwater shooting state, the second lens group G2 and the third lens group G3 are driven in the image plane direction, and the underwater shooting state is changed to the land shooting state. In case, second
The lens group G2 and the third lens group G3 are driven in the object direction to correct a change in field curvature and a change in image formation position due to a change in photographing state. When the shooting state is automatically switched using a sensor without providing the switch member 42, the land shooting state may be switched to the underwater shooting state after detecting that the optical system ZL is completely underwater. The land shooting state may be switched to the underwater shooting state after detecting that at least a part of the optical system ZL is underwater, and the underwater shooting state is detected after detecting that at least a part of the optical system ZL is on land. It is good also as switching to a land photography state from, and it can change suitably.

Next, the optical system ZL1 provided in the amphibious variable magnification lens apparatus 10 according to the first embodiment will be described with reference to FIGS. The characteristic configuration of the optical system ZL1 that is common to the second embodiment described later is as described above.

In order to avoid complication of explanation due to an increase in the number of digits of the reference code, each reference code in FIG.
Each embodiment is used independently. Therefore, even if the reference numerals common to the drawings according to the other embodiments are attached, they are not necessarily the same configuration as the other embodiments.

In each embodiment, the d-line (wavelength: 587.5620 nm) and g-line (wavelength: 435.83) are calculated as aberration characteristics.
50nm) is selected.

The optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment includes a first lens group G1 having a positive refractive power and a negative refractive power, which are arranged in order from the object side, as shown in FIG. A second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, and a fourth lens having a positive refractive power.
It consists of a lens group G4.

  The first lens group G1 includes a positive meniscus lens L11 having a convex surface directed toward the object side.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface facing the image surface side, a negative lens L22 having a biconcave shape, and a negative meniscus lens L having a concave surface facing the image surface side.
23 and a cemented positive lens with a positive meniscus lens L24 having a convex surface facing the object side. The image side surface of the negative meniscus lens L21 is aspheric. The image side surface of the biconcave negative lens L22 is aspheric.

  The third lens group G3 is composed of a biconvex positive lens L31.

The fourth lens group G4 includes, in order from the object side, a cemented negative lens of a biconvex positive lens L41 and a biconcave negative lens L42, a negative meniscus lens L43 having a concave surface facing the image plane, and both It consists of a cemented positive lens with a convex positive lens L44, and a cemented negative lens with a biconvex positive lens L45 and a negative meniscus lens L46 with a concave surface facing the object side. The image side surface of the negative meniscus lens L46 is aspheric.

  An iris diaphragm S is disposed adjacent to the object side of the fourth lens group G4.

A filter group F is disposed on the image side of the fourth lens group G4. The filter group F includes a low-pass filter for cutting a spatial frequency equal to or higher than the limit resolution of an image sensor such as a CCD or CMOS disposed on the image plane I, a cover glass of the image sensor, and the like.

The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The first lens group G1 is always fixed with respect to the image plane I in the optical axis direction.

The second lens group G2 is moved by the first drive mechanism 22. When zooming from the wide-angle end state to the telephoto end state, the second lens group G2 moves in the image plane direction in both the land photographing state and the underwater photographing state. When focusing from an object at infinity to an object at a short distance, the object does not move in the land photographing state but moves in the object direction in the underwater photographing state. Further, when changing from the on-land shooting state to the underwater shooting state, the camera moves in the image plane direction. When changing from the underwater shooting state to the land shooting state, the camera moves toward the object.

The third lens group G3 is moved by the second drive mechanism 32. When changing the magnification from the wide-angle end state to the telephoto end state, the fourth lens group G3 is used in both the land photographing state and the underwater photographing state.
4 moves in accordance with the movement in the optical axis direction. When focusing from an object at infinity to an object at a short distance, the object moves in the image plane direction in the land photographing state and does not move in the underwater photographing state. Further, when changing from the on-land shooting state to the underwater shooting state, the camera moves in the image plane direction. When changing from the underwater shooting state to the land shooting state, the camera moves toward the object.

The fourth lens group G4 moves in accordance with the rotation operation of the operation member 6. When zooming from the wide-angle end state to the telephoto end state, the fourth lens group G4 moves in the object direction in both the land photographing state and the underwater photographing state.

As described above, in the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment, by changing the lens group that moves at the time of focusing between the land photographing state and the underwater photographing state, the land photographing state and the underwater photographing state. In both states, it is possible to suppress the focusing variation of the curvature of field, and to achieve good imaging performance over the entire photographing distance from infinity to short distance over the entire zoom range.

Further, in the optical system ZL1, when the land photographing state and the underwater photographing state are changed, the positions of the second lens group G2 and the third lens group G3 are changed, so that the imaging position is constant in the land photographing state and the underwater photographing state. It is possible to satisfactorily correct various aberrations including field curvature in both the land photographing state and the underwater photographing state while keeping the same.

Table 1 below lists specifications of the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment. Surface numbers 1 to 23 in Table 1 correspond to the optical surfaces m1 to m23 shown in FIG.

In [Lens data] in the table, the surface number is the order of the optical surfaces from the object side along the direction in which the light beam travels, R is the radius of curvature of each optical surface, and D is the next optical surface from each optical surface (or The distance between surfaces on the optical axis to the image plane), nd is the refractive index of the material of the optical member with respect to the d-line, and νd is the Abbe number with respect to the d-line of the material of the optical member. The object plane is the object plane, (variable) is the variable plane spacing, the curvature radius “∞” is the plane or aperture, (aperture S) is the iris diaphragm S, and the image plane is the image plane I. The refractive index of air “1.000000” is omitted. If the optical surface is aspheric,
The surface number is marked with an asterisk (*), and the paraxial radius of curvature column shows the paraxial radius of curvature.

In [Aspherical data] in the table, the shape of the aspherical surface shown in [Lens data] is shown by the following equation (a). X (y) is the distance along the optical axis direction from the tangential plane at the apex of the aspheric surface to the position on the aspheric surface at height y, R is the radius of curvature of the reference sphere (paraxial radius of curvature), and κ
Denotes a conic constant, and Ai denotes an i-th aspherical coefficient. “E-n” indicates “× 10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 × 10 ⁻⁵ .

X (y) = (y ² / R) / {1+ (1−κ × y ² / R ² ) ^1/2 } + A4 × y ⁴ + A6 × y ⁶ + A
8 × y ⁸ + A10 × y ¹⁰ (a)

In [Various data] in the table, f is the focal length of the entire lens system, FNO is the F number, 2
ω is the angle of view (unit: °), Y is the image height, TL is the total lens length (distance from the lens surface closest to the object side on the optical axis to the paraxial image plane), and Bf is the back focus (on the optical axis). The distance from the lens surface closest to the image plane to the paraxial image plane). Di is a variable interval, and the i-th surface and (i + 1) -th surface
Indicates the variable spacing of the surface.

[Focusing movement amount] in the table indicates the movement amount of each lens group when focusing from an object distance of infinity to an object distance of 300 mm (where the positive sign indicates the movement amount in the image plane direction and the negative sign) Represents the amount of movement in the object direction).

In [Lens Group Data] in the table, the start surface number (the most object-side lens surface number), the end surface number (the most image-side lens surface number), and the focal length in the air are shown.

The [Position data of each lens group] in the table is infinite at each focal length in the land shooting state and the underwater shooting state with reference to the position of each lens group in the infinity shooting state in the wide-angle end state in the land shooting state. The position of each lens group in the far shooting state is shown. The sign is positive in the image plane direction.

Hereinafter, in all the specification values, “mm” is generally used for the focal length f, curvature radius R, surface interval D, and other lengths, etc. unless otherwise specified. Since the same optical performance can be obtained even if proportional expansion or proportional reduction is performed, the present invention is not limited to this.
Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The description of the above table is the same in other embodiments.

(Table 1)
[Lens data]
Surface number R D nd νd
Object ∞
1 44.7198 7.4084 1.516800 63.88
2 85.2163 D2 (variable)
3 40.9646 1.6000 1.694120 53.35
* 4 9.2893 8.5100
5 -185.3860 1.0000 1.773870 47.25
* 6 13.9269 4.1000
7 59.8385 1.0000 1.497820 82.57
8 14.0189 3.5500 1.834000 37.18
9 123.5879 D9 (variable)
10 79.9753 1.3500 1.581440 40.98
11 -39.3744 D11 (variable)
12 ∞ 0.8000 (Aperture S)
13 13.2562 2.0000 1.497820 82.57
14 -15.0400 0.8000 1.744000 44.80
15 26.7221 1.3300
16 13.3337 0.8000 1.850 260 32.35
17 10.0972 3.1500 1.516800 63.88
18 -24.7694 4.4400
19 53.6117 4.0000 1.497820 82.57
20 -10.0893 1.0000 1.773870 47.25
* 21 -46.0788 D21 (variable)
22 ∞ 2.7900 1.516800 64.11
23 ∞ Bf
Image plane ∞

[Aspherical data]
4th surface κ = -1.1413
A4 = + 2.64855E-04
A6 = -1.38810E-06
A8 = + 1.32889E-08
A10 = -6.76083E-11

6th surface κ = -4.2267
A4 = + 2.73709E-04
A6 = -1.40274E-06
A8 = + 1.65481E-08
A10 = -4.59585E-11

21st surface κ = +0.7548
A4 = + 1.41639E-04
A6 = + 1.03122E-06
A8 = -6.77508E-09
A10 = + 2.70786E-10

[Various data]
(Land shooting state)
f 7.20 9.20 13.60
FNO 3.55 3.85 4.55
2ω 96.87 81.79 60.29
Y 8.00 8.00 8.00
TL 83.05 83.05 83.05
D2 2.002 6.557 9.751
D9 14.725 8.893 1.600
D11 5.585 4.566 3.468
D21 8.950 11.247 16.443
Bf 2.162 2.162 2.162

(Underwater shooting)
f 6.10 7.56 10.93
FNO 3.54 3.85 4.54
2ω 90.47 77.30 57.21
Y 8.00 8.00 8.00
TL 83.05 83.05 83.05
D2 5.528 8.768 10.717
D9 15.785 10.099 2.995
D11 1.000 1.149 1.108
D21 8.950 11.247 16.443
Bf 2.162 2.162 2.162

[Focusing distance]
(Land shooting state)
f 7.20 9.20 13.60
First lens group 0.000 0.000 0.000
Second lens group 0.000 0.000 0.000
Third lens group 0.679 0.733 0.836
Fourth lens group 0.000 0.000 0.000

(Underwater shooting)
f 6.10 7.56 10.93
First lens group 0.000 0.000 0.000
Second lens group -0.618 -0.600 -0.590
Third lens group 0.000 0.000 0.000
Fourth lens group 0.000 0.000 0.000

[Lens group data]
Group Start surface End surface Group focal length First lens group 1 2 171.404
Second lens group 3 9 -10.875
Third lens group 10 11 45.567
Fourth lens group 13 21 22.715

[Position data for each lens group]
(Land shooting state)
f 7.20 9.20 13.60
First lens group 0.000 0.000 0.000
Second lens group 0.000 4.555 7.749
Third lens group 0.000 -1.278 -5.376
Fourth lens group 0.000 -2.297 -7.493

(Underwater shooting)
f 6.10 7.56 10.93
First lens group 0.000 0.000 0.000
Second lens group 3.526 6.766 8.715
Third lens group 4.585 2.139 -3.016
Fourth lens group 0.000 -2.297 -7.493

FIG. 4 is a diagram showing various aberrations with respect to the d-line and the g-line in the infinitely focused state in the land photographing state based on the design value of the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment. (
a) shows the wide-angle end state, (b) shows the intermediate focal length state, and (c) shows the telephoto end state. FIG. 5 is a diagram showing various aberrations with respect to the d-line and the g-line in the infinite focus state in the underwater photographing state based on the design value of the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment. (A)
Is the wide-angle end state, (b) is the intermediate focal length state, and (c) is the telephoto end state. FIG. 6 shows the d-line and g-line in the short-distance in-focus state with an object image distance of 300 mm in the land-based photographing state based on the design value of the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment. FIG. 4A is a diagram illustrating various aberrations, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 7 shows the d-line and g in a short-distance focusing state with an object-to-image distance of 300 mm in an underwater shooting state based on the design value of the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment.
FIG. 4A is a diagram illustrating various aberrations with respect to a line, where FIG. 5A illustrates a wide-angle end state, FIG. 5B illustrates an intermediate focal length state, and FIG.

In each aberration diagram, FNO represents an F number, and Y represents an image height. Further, d represents the aberration at the d line, and g represents the aberration at the g line. Those without d and g indicate aberration at the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane.

  The explanation of the above aberration diagrams is the same in the other examples described later.

From each aberration diagram, the optical system ZL1 of the amphibious variable magnification lens apparatus 10 according to the first embodiment extends from the infinite focus state to the short distance focus state in the entire zoom range in both the land photographing state and the underwater photographing state. It can be seen that various aberrations such as distortion and curvature of field are well corrected and have high imaging performance.

In the present embodiment, as a method for discriminating between the land shooting state and the underwater shooting state, as described above, a method is adopted in which the switch member 42 is provided in the housing 1 and is identified according to the switching operation of the photographer. However, it is not limited to this. For example, it is also possible to employ a method of automatically identifying two terminals by exposing them to the outside of the housing 1 and measuring the electrical resistance between the terminals. With this configuration, convenience can be further enhanced.

(Second Embodiment)
An amphibious variable power lens apparatus according to the second embodiment will be described. As shown in FIG. 8, the amphibious variable magnification lens apparatus 100 according to the second embodiment includes a first lens group G1 having negative refractive power arranged in order from the object side in a housing 101, and first negative refractive power. An optical system ZL (ZL2) including a two-lens group G2, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power is provided.

The first lens group G1 is fixed on the optical axis via the first lens group fixing portion 101a to the housing 101, and the second lens group G2, the third lens group G3, and the fourth lens group G4 are provided. It is hold | maintained by the member mentioned later in the housing | casing 101 so that each can move independently along an optical axis.

A focal length change switch member 152 for changing the focal length is provided on the outside of the housing 101. A focal length detection unit 151 that detects a focal length change request by an operation of the focal length change switch member 152 is disposed in the housing 101.

A shooting state changeover switch member 142 for switching between an underwater shooting state and a land shooting state is provided on the outside of the housing 101. In the housing 101, the photographing state changeover switch member 142 is provided.
A shooting state identification unit 141 for identifying the shooting state changed in step S1 is arranged.

A mount member 111 is fixed to the image-side end portion 101 b of the housing 101, and the amphibious variable power lens device 100 is fixed to an imaging device described later by the mount member 111.

The second lens group G2 is held by the second lens group lens frame 102, and this lens frame 102 is slidably supported by a first support member 121 disposed in the housing 101, and the control shown in FIG. The first drive mechanism 122 is configured to move along the optical axis based on a control signal from the unit 171.

The third lens group G3 is held by the third lens group lens frame 103, and the lens frame 103 is slidably supported by a second support member 131 disposed in the housing 101, and is controlled by a control unit 171.
The second drive mechanism 132 is configured to move along the optical axis based on the control signal from.

The fourth lens group G4 is held by the fourth lens group lens frame 104, and this lens frame 104 is slidably supported by a second support member 131 disposed in the housing 101, and is controlled by a controller 171.
The third drive mechanism 182 is configured to move along the optical axis based on the control signal from.

The amphibious variable magnification lens apparatus 100 according to the second embodiment includes a second lens group G2, a third lens group G3, and a fourth lens group that are set for each focal length in each of the land photographing state and the underwater photographing state. The position information on the optical axis of G4 is stored in the storage unit 161 shown in FIG. The positional information of the second lens group G2, the third lens group G3, and the fourth lens group G4 having the focal lengths not stored is set by the control unit 171 performing interpolation processing or the like based on the stored positional information. can do.

  Thus, the amphibious variable power lens apparatus 100 according to the second embodiment is configured.

And in the amphibious variable power lens apparatus 100 according to the second embodiment, as shown in FIG.
The shooting state identified by the shooting state identification unit 141 by operating the shooting state changeover switch member 142 is transmitted to the control unit 171. The focal length change request detected by the focal length detection unit 151 by operating the focal length change switch member 152 is transmitted to the control unit 171.

The control unit 171 includes a second lens group G2 corresponding to the transmitted shooting state and focal length request,
Position information on the optical axis of the third lens group G3 and the fourth lens group G4 is read from the storage unit 161, and the second lens group G2 is connected via the first drive mechanism 122 to the second lens group G2 via the second drive mechanism 132. The third lens group G3 and the fourth lens group G4 are independently moved to a predetermined optical axis position via the third drive mechanism 182.

At the time of focusing, the control unit 171 moves the second lens group G2 via the first drive mechanism 122 in the underwater shooting state according to the shooting state identified by the shooting state identification unit 141. In the case of land shooting, the control unit 171 moves the third lens group G3 via the second drive mechanism 132 to perform focusing.

Further, when the switch member 142 is operated and the shooting state identified by the shooting state identification unit 141 is changed, the control unit 171 refers to the storage unit 161 and performs the second operation via the first drive mechanism 122. The lens group G2 is moved, and the third lens group G3 is moved via the second drive mechanism 132, so that the change in the field curvature and the change in the imaging position due to the change in the photographing state are corrected. More specifically, when the land photographing state is changed to the underwater photographing state, the second lens group G2 is used.
And the third lens group G3 are driven in the image plane direction, and when the underwater shooting state is changed to the land shooting state, the second lens group G2 and the third lens group G3 are driven in the object direction to change the shooting state. Changes in the curvature of field and changes in the imaging position due to the change in the image.

Next, an optical system ZL2 included in the amphibious variable magnification lens apparatus 100 according to the second embodiment will be described with reference to FIGS. The characteristic configuration of the optical system ZL2 that is common to the first embodiment is as described above.

As shown in FIG. 10, the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment includes a first lens group G1 having negative refractive power, which is arranged in order from the object side, and negative refractive power. A second lens group G2 having a positive refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power.

  The first lens group G1 includes a negative meniscus lens L11 having a convex surface directed toward the object side.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 having a concave surface facing the image surface side, a negative lens L22 having a biconcave shape, and a negative meniscus lens L having a concave surface facing the image surface side.
23 and a cemented positive lens with a positive meniscus lens L24 having a convex surface facing the object side. The image side surface of the negative meniscus lens L21 is aspheric. The image side surface of the biconcave negative lens L22 is aspheric.

  The third lens group G3 is composed of a biconvex positive lens L31.

The fourth lens group G4 includes, in order from the object side, a cemented negative lens of a biconvex positive lens L41 and a biconcave negative lens L42, a negative meniscus lens L43 having a concave surface facing the image plane, and both It consists of a cemented positive lens with a convex positive lens L44, and a cemented negative lens with a biconvex positive lens L45 and a negative meniscus lens L46 with a concave surface facing the object side. The image side surface of the negative meniscus lens L46 is aspheric.

  An iris diaphragm S is disposed adjacent to the object side of the fourth lens group G4.

A filter group F is disposed on the image side of the fourth lens group G4. The filter group F includes a low-pass filter for cutting a spatial frequency equal to or higher than the limit resolution of an image sensor such as a CCD or CMOS disposed on the image plane I, a cover glass of the image sensor, and the like.

The image plane I is formed on an image sensor (not shown), and the image sensor is composed of a CCD, a CMOS, or the like.

  The first lens group G1 is always fixed with respect to the image plane I in the optical axis direction.

The second lens group G2 is moved by the first drive mechanism 122. When zooming from the wide-angle end state to the telephoto end state, the second lens group G2 moves in the image plane direction in both the land photographing state and the underwater photographing state. When focusing from an object at infinity to an object at a short distance, the object does not move in the land photographing state but moves in the object direction in the underwater photographing state. Further, when changing from the on-land shooting state to the underwater shooting state, the camera moves in the image plane direction. When changing from the underwater shooting state to the land shooting state, the camera moves toward the object.

The third lens group G3 is moved by the second drive mechanism 132, and moves to the object side in both the land photographing state and the underwater photographing state when zooming from the wide-angle end state to the telephoto end state. When focusing from an object at infinity to an object at a short distance, the object moves in the image plane direction in the land photographing state and does not move in the underwater photographing state. Further, when changing from the on-land shooting state to the underwater shooting state, the camera moves in the image plane direction. When changing from the underwater shooting state to the land shooting state, the camera moves toward the object.

The fourth lens group G4 is moved by the third drive mechanism 182. When zooming from the wide-angle end state to the telephoto end state, the fourth lens group G4 moves in the object direction in both the land photographing state and the underwater photographing state.

As described above, in the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment, by changing the lens group that moves at the time of focusing between the land photographing state and the underwater photographing state, the land photographing state and the underwater photographing state are obtained. In both cases, it is possible to suppress the focusing variation of the curvature of field and achieve good imaging performance over the entire photographing distance from infinity to short distance over the entire zoom range.

Further, in the optical system ZL2, when the land photographing state and the underwater photographing state are changed, the positions of the second lens group G2 and the third lens group G3 are changed, so that the imaging position is constant in the land photographing state and the underwater photographing state. It is possible to satisfactorily correct various aberrations including field curvature in both the land photographing state and the underwater photographing state while keeping the same.

Table 2 below lists specifications of the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment. Surface numbers 1 to 23 in Table 2 correspond to the optical surfaces m1 to m23 shown in FIG.

(Table 2)
[Lens data]
Surface number R D nd νd
Object ∞
1 39.4129 6.5983 1.516800 63.88
2 32.2463 D2 (variable)
3 21.3416 1.6000 1.694120 53.35
* 4 9.1366 8.5100
5 -101.6596 1.0000 1.773870 47.25
* 6 13.7116 4.1000
7 42.4699 1.0000 1.497820 82.57
8 14.6837 3.5500 1.834000 37.18
9 108.9141 D9 (variable)
10 72.2919 1.3500 1.581440 40.98
11 -43.0390 D11 (variable)
12 ∞ 0.8000 (Aperture S)
13 14.4857 2.0000 1.497820 82.57
14 -14.0908 0.8000 1.744000 44.80
15 33.6293 1.3300
16 12.9152 0.8000 1.850260 32.35
17 10.0596 3.1500 1.516800 63.88
18 -23.5021 4.4400
19 78.9820 4.0000 1.497820 82.57
20 -8.9039 1.0000 1.773870 47.25
* 21 -50.0522 D21 (variable)
22 ∞ 2.7900 1.516800 64.11
23 ∞ Bf
Image plane ∞

[Aspherical data]
4th surface κ = -1.1413
A4 = + 2.71136E-04
A6 = -1.43827E-06
A8 = + 1.29997E-08
A10 = -7.11747E-11

6th surface κ = -4.2267
A4 = + 2.90451E-04
A6 = -1.49834E-06
A8 = + 1.79993E-08
A10 = -6.44088E-11

21st surface κ = +0.7548
A4 = + 1.63105E-04
A6 = + 9.56800E-07
A8 = + 5.91250E-09
A10 = + 3.58088E-11

[Various data]
(Land shooting state)
f 7.20 9.20 13.60
FNO 3.55 3.93 4.76
2ω 96.99 81.30 60.09
Y 8.00 8.00 8.00
TL 83.07 83.07 83.07
D2 2.003 6.774 9.923
D9 16.478 9.353 1.600
D11 5.416 5.079 4.001
D21 8.177 10.868 16.551
Bf 2.178 2.178 2.178

(Underwater shooting)
f 5.82 7.33 10.77
FNO 3.55 3.93 4.75
2ω 92.95 78.21 57.48
Y 8.00 8.00 8.00
TL 83.07 83.07 83.07
D2 5.205 9.229 11.137
D9 17.690 10.673 3.116
D11 1.003 1.305 1.271
D21 8.177 10.868 16.551
Bf 2.178 2.178 2.178

[Focusing distance]
(Land shooting state)
f 7.20 9.20 13.60
First lens group 0.000 0.000 0.000
Second lens group 0.000 0.000 0.000
Third lens group 0.736 0.740 0.806
Fourth lens group 0.000 0.000 0.000

(Underwater shooting)
f 5.82 7.33 10.77
First lens group 0.000 0.000 0.000
Second lens group -0.634 -0.580 -0.557
Third lens group 0.000 0.000 0.000
Fourth lens group 0.000 0.000 0.000

[Lens group data]
Group Start surface End surface Group focal length First lens group 1 2 -499.997
Second lens group 3 9 -13.044
Third lens group 10 11 46.599
Fourth lens group 13 21 22.986

[Position data for each lens group]
(Land shooting state)
f 7.20 9.20 13.60
First lens group 0.000 0.000 0.000
Second lens group 0.000 4.771 7.920
Third lens group 0.000 -2.354 -6.959
Fourth lens group 0.000 -2.691 -8.374

(Underwater shooting)
f 5.82 7.33 10.77
First lens group 0.000 0.000 0.000
Second lens group 3.202 7.226 9.134
Third lens group 4.414 1.421 -4.228
Fourth lens group 0.000 -2.691 -8.374

FIG. 11 is a diagram showing various aberrations with respect to the d-line and the g-line in the infinitely focused state in the land photographing state, based on the design value of the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment. (A) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 12 is a diagram of various aberrations for the d-line and g-line in the infinite focus state in the underwater shooting state, based on the design value of the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment. (A) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 13 is a graph for d-line and g-line in a short-distance in-focus state with an object-image distance of 300 mm in a land-based photographing state based on the design value of the optical system ZL2 of the amphibious variable magnification lens device 100 according to the second embodiment. FIG. 4A is a diagram illustrating various aberrations, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state. FIG. 14 shows the d-line and g-line in the short-distance focusing state with an object-image distance of 300 mm in the underwater shooting state based on the design value of the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment. FIG. 4A is a diagram illustrating various aberrations, in which (a) shows a wide-angle end state, (b) shows an intermediate focal length state, and (c) shows a telephoto end state.

From each aberration diagram, the optical system ZL2 of the amphibious variable magnification lens apparatus 100 according to the second embodiment is:
Various aberrations such as distortion and curvature of field are well corrected and have high imaging performance over the entire zoom range from infinite focus to close focus in both the land and underwater shooting conditions. I understand.

In the present embodiment, as a method for identifying the land photographing state and the underwater photographing state, as described above, the photographing state changeover switch member 142 is provided in the housing 101, and the method is identified according to the photographer's switching operation. However, it is not limited to this. For example, housing 1
It is also possible to employ a method of automatically identifying by providing two terminals so as to be exposed outside of 01 and measuring the electrical resistance between the terminals. With this configuration, convenience can be further enhanced.

Next, a camera (imaging device) 90 equipped with the amphibious variable magnification lens device according to the present embodiment will be described with reference to FIG. Here, the case where the amphibious variable power lens apparatus 10 according to the first embodiment is mounted will be described, but the same applies to the amphibious variable power lens apparatus 100 according to the second embodiment.

As shown in FIG. 15, the camera 90 includes an amphibious variable power lens device 10 according to the first embodiment.
Is an amphibious camera with interchangeable lenses. In this camera 90,
Light from a subject (not shown) is collected by the optical system ZL1 of the amphibious variable magnification lens apparatus 10 and imaged on the image sensor 91. The subject image formed on the image sensor 91 is converted into a video signal by an electric circuit (not shown) and displayed on the monitor screen 92 so that the photographer can observe it. The photographer operates the switch member 42 (see FIG. 1) to set the photographing state, and the operation member 6 (FIG. 1).
(Refer to FIG. 6), the focal length is set, and then the subject is observed through the monitor screen 92 while half-pressing a release button (not shown) to determine the photographing composition. Subsequently, when the release button is fully pressed by the photographer, in the camera 90, light from the subject is received by the image sensor 91,
A captured image is acquired and recorded in a memory (not shown).

According to the amphibious camera 90 according to the present embodiment having the above-described configuration, the amphibious zoom lens device 10 according to the first embodiment provides a land shooting state and an underwater shooting state with a simple configuration. In both cases, zooming and focusing are possible, and a camera having excellent optical performance can be realized.

The camera 90 shown in FIG. 15 is not only a type in which the amphibious zoom lens device 10 is detachably mounted, but also a type in which the camera body and the amphibious zoom lens device 10 are integrally formed. It may be a thing. Further, the camera 90 may be a so-called single-lens reflex camera having a quick return mirror or a video camera that mainly performs moving image shooting.

Then, the manufacturing method of the amphibious variable magnification lens apparatus which concerns on this embodiment is demonstrated, referring FIG. Here, the case where the amphibious variable power lens apparatus 10 according to the first embodiment is manufactured will be described, but the same applies to the amphibious variable power lens apparatus 100 according to the second embodiment.

First, it has a first lens group and at least three moving lens groups (for example, a second lens group G2, a third lens group G3, and a fourth lens group G4) arranged in order from the object side along the optical axis. Thus, each lens is arranged in the housing 1 (step ST10). At this time, the first lens group G1 is fixed, and each lens is arranged in the housing 1 so as to perform zooming by moving the moving lens group along the optical axis (step ST20). Further, the moving lens groups (for example, the third lens group G3 in the land photographing state and the second lens group G2 in the underwater photographing state) that are different in the land photographing state and the underwater photographing state are moved along the optical axis. Each lens is arranged in the housing 1 so as to focus on (step ST30).

As an example of the lens arrangement in the present embodiment, in the amphibious variable magnification lens apparatus 10 according to the first embodiment, as described above (see FIG. 3), the first lens group G1 has a convex surface directed toward the object side. The positive meniscus lens L11 is disposed in the housing 1. As the second lens group G2, in order from the object side, a negative meniscus lens L21 having a concave surface facing the image surface side, a biconcave negative lens L22, a negative meniscus lens L23 having a concave surface facing the image surface side, and the object side A positive cemented lens with a positive meniscus lens L24 having a convex surface facing the lens is disposed in the housing 1. Third lens group G
3, a biconvex positive lens L <b> 31 is arranged in the housing 1. As the fourth lens group G4, in order from the object side, a cemented negative lens of a biconvex positive lens L41 and a biconcave negative lens L42, a negative meniscus lens L43 having a concave surface facing the image surface side, and a biconvex shape A cemented positive lens with the positive lens L44, a biconvex positive lens L45, and a cemented negative lens with a negative meniscus lens L46 having a concave surface facing the object side are arranged in the housing 1.

According to such a manufacturing method, the amphibious variable power lens apparatus 10 which has a simple configuration and can perform zooming and focusing in both the land photographing state and the underwater photographing state and has excellent optical performance. Can be manufactured.

In order to make the present invention easy to understand so far, the configuration requirements of the embodiment have been described.
It goes without saying that the present invention is not limited to this.

For example, in each of the above embodiments, an optical system having a four-group configuration has been described. However, the present invention can also be applied to other group configurations such as a configuration having five or more groups. Further, a configuration in which a lens or a lens group is added to the most object side or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group refers to a portion having at least one lens separated by an air interval that changes during focusing or zooming. In the case of the configuration of five groups or more, the number of moving lens groups is not limited to three, and four or more moving lens groups can be applied. When there are four or more moving lens groups, the storage unit 61 is used.
, 161 can store the positional information of two to four or four or more moving lens groups, and thereby achieve the same effect as the above embodiment.

In each embodiment, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to be a focusing lens group that performs focusing from an object at infinity to a near object. This focusing lens group can be applied to autofocus, and is also suitable for driving a motor for autofocus (using an ultrasonic motor or the like). In particular, the second lens group G2 and the third lens group G3 are preferably the focusing lens group.

In each embodiment, the lens surface may be formed of a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and optical performance deterioration due to errors in processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is an aspheric surface, the aspheric surface is an aspheric surface by grinding, a glass mold aspheric surface made of glass with an aspheric shape, or a composite aspheric surface made of resin with an aspheric shape on the glass surface. Any aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In each embodiment, each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength region in order to reduce flare and ghost and achieve high optical performance with high contrast.

The “underwater photographing state” may be a photographing state in a liquid containing impurities as well as a photographing state in pure water.

In addition, the switching between the underwater shooting state and the land shooting state is performed by the imaging device 90 including the optical system ZL.
The shooting mode may be switched by using an operation member or an external device.

DESCRIPTION OF SYMBOLS 10,100 Amphibious variable-power lens apparatus 1,101 Housing | casing 11,111 Mount member 2,102 2nd lens group lens frame 3,103 3rd lens group lens frame 4,104 4th lens group lens frame 5 Long hole 6 Operation member (for changing focal length)
22, 122 First drive mechanism 32, 132 Second drive mechanism 51, 151 Focal length detection unit 41, 141 Shooting state identification unit 61, 161 Storage unit 71, 171 Control unit 42, 142 Switch member (for shooting state switching) )
152 Switch member (for changing focal length)
182 Third drive mechanism 90 Amphibious camera (imaging device)
91 Image sensor 92 Monitor screen ZL (ZL1, ZL2) Optical system G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group S Aperture F Filter group I Image surface

Claims (6)

A variable magnification optical system that can be used underwater and on land,
A first lens group and at least three lens groups arranged in order from the object side along the optical axis;
Fixing the position of the first lens group on the optical axis, and performing zooming by moving at least one of the three lens groups along the optical axis;
Focusing in water by moving at least part of the three lens groups along the optical axis as a first focusing lens group,
Focusing on land by moving at least part of the three lens groups along the optical axis as a second focusing lens group,
A variable power optical system characterized in that the first focusing lens group and the second focusing lens group differ in at least one of configuration and movement locus. The three lens groups have a lens group having negative refractive power,
Among the lens groups having negative refractive power, the lens group located closest to the object side is the first lens group.
A focusing lens group,
2. The variable magnification optical system according to claim 1, wherein a lens group arranged in order along the optical axis on the image side of the first focusing lens group is the second focusing lens group. When the state changes between land use and underwater use,
3. The zoom optical system according to claim 1, wherein at least two of the three lens groups are moved along the optical axis. The three lens groups include, in order from the object side, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power,
The zooming is performed by changing an interval between the first lens group and the second lens group and an interval between the second lens group and the third lens group. The zoom optical system according to any one of the above.   An imaging apparatus comprising the variable magnification optical system according to claim 1. A method of manufacturing a variable magnification optical system that can be used underwater and on land,
A first lens group and at least three lens groups arranged in order from the object side along the optical axis;
Fixing the position of the first lens group on the optical axis, and performing zooming by moving at least one of the three lens groups along the optical axis;
Focusing in water by moving at least part of the three lens groups along the optical axis as a first focusing lens group,
Focusing on land by moving at least part of the three lens groups along the optical axis as a second focusing lens group,
The first focusing lens group and the second focusing lens group are configured so that at least one of the configuration and the movement locus is different.
A method of manufacturing a variable magnification optical system, wherein each lens is arranged in a housing.

Images