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WO2024122650A1 - Système optique à grossissement variable, instrument optique et procédé de fabrication de système optique à grossissement variable - Google Patents

Système optique à grossissement variable, instrument optique et procédé de fabrication de système optique à grossissement variable Download PDF

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Publication number
WO2024122650A1
WO2024122650A1 PCT/JP2023/044218 JP2023044218W WO2024122650A1 WO 2024122650 A1 WO2024122650 A1 WO 2024122650A1 JP 2023044218 W JP2023044218 W JP 2023044218W WO 2024122650 A1 WO2024122650 A1 WO 2024122650A1
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Prior art keywords
lens group
end state
telephoto end
optical system
group
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PCT/JP2023/044218
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English (en)
Japanese (ja)
Inventor
京也 徳永
知之 幸島
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株式会社ニコン
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Publication of WO2024122650A1 publication Critical patent/WO2024122650A1/fr

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
    • G02B15/20—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having an additional movable lens or lens group for varying the objective focal length

Definitions

  • the present invention relates to a variable magnification optical system, an optical device, and a method for manufacturing a variable magnification optical system.
  • Variable magnification optical systems suitable for photo cameras, electronic still cameras, video cameras, etc. have been proposed in the past (see, for example, Patent Document 1). With such variable magnification optical systems, it is difficult to achieve a small size while also achieving bright and good optical performance.
  • a first variable magnification optical system comprises, arranged in order from the object side along the optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, wherein, when varying magnification from the wide-angle end state to a first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and N1 lens groups move along the optical axis, and, when varying magnification from the first telephoto end state to the second telephoto end state, the first lens group is fixed with respect to the image plane, and N2 lens groups move along the optical axis, N1 is an integer equal to or greater than 3, and N2 is a positive integer less than N1, and the following conditional expression is satisfied: 0.10 ⁇ MB/MA ⁇ 2.00 ft1/ft2 ⁇ 0.95 Where, MA: the movement amount of the lens group having the largest movement amount when changing magnification
  • a second variable magnification optical system comprises, arranged in order from the object side along the optical axis, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, wherein, when varying magnification from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and the second lens group moves along the optical axis, and, when varying magnification from the first telephoto end state to the second telephoto end state, the first lens group and the second lens group are fixed with respect to the image plane, and at least a portion of the rear group moves along the optical axis, and the following conditional expression is satisfied: 0.75 ⁇ MG2/(-f2) ⁇ 1.30 ft1/ft2 ⁇ 0.95 where f2 is the focal length of the second lens group, MG2 is the movement amount of the second lens group when changing magnification from
  • the optical device according to the present invention is configured with the variable magnification optical system described above.
  • a first manufacturing method of a variable magnification optical system is a manufacturing method of a variable magnification optical system consisting of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis
  • the manufacturing method includes a step of arranging each lens in a lens barrel so that, when changing magnification from the wide-angle end state to the first telephoto end state, the interval between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and N1 lens groups move along the optical axis, when changing magnification from the first telephoto end state to the second telephoto end state, the first lens group is fixed with respect to the image plane, and N2 lens groups move along the optical axis, N1 is an integer equal to or greater than 3, and N2 is a positive integer smaller than N1, and the manufacturing method of a variable magnification optical system includes a
  • a second manufacturing method of a variable magnification optical system is a manufacturing method of a variable magnification optical system consisting of a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear group, arranged in order from the object side along the optical axis, and includes a step of arranging each lens within the lens barrel so that, when varying magnification from the wide-angle end state to the first telephoto end state, the spacing between adjacent lens groups changes, the first lens group is fixed with respect to the image plane, and the second lens group moves along the optical axis, and, when varying magnification from the first telephoto end state to the second telephoto end state, the first lens group and the second lens group are fixed with respect to the image plane, and at least a portion of the rear group moves along the optical axis, and the following conditional expression is satisfied: 0.75 ⁇ MG2/(-f2) ⁇ 1.30 ft1/ft2 ⁇
  • the optical system according to the third aspect of the present invention includes a lens group for magnification change that is moved in the optical axis direction when the magnification is changed from the wide-angle end state to the first telephoto end state, and a lens group for focusing that is moved in the optical axis direction when the magnification is changed from the wide-angle end state to the first telephoto end state and is also moved in the optical axis direction for focusing, and is configured to switch from the first telephoto state to a second telephoto state with a higher magnification by moving the lens group for focusing along the optical axis while keeping the lens group for magnification fixed along the optical axis.
  • FIG. 2 is a diagram showing a lens configuration of a variable magnification optical system according to a first example.
  • FIG. 2 is a schematic diagram showing a lens position control mechanism according to the first embodiment.
  • 5A to 5C are diagrams illustrating various aberrations of the variable magnification optical system according to Example 1 when focused on an object at infinity in the wide-angle end state.
  • 5A to 5C are diagrams illustrating various aberrations of the variable magnification optical system according to Example 1 when focused on an object at infinity in the first telephoto end state.
  • 5A to 5C are diagrams illustrating various aberrations of the variable magnification optical system according to Example 1 when focused on an object at infinity in the second telephoto end state.
  • FIG. 13 is a diagram showing a lens configuration of a variable magnification optical system according to Example 2.
  • FIG. 11 is a schematic diagram showing a lens position control mechanism according to a second embodiment.
  • 13A to 13C are diagrams illustrating various aberrations when the variable magnification optical system according to Example 2 is in the wide-angle end state and focused on an object at infinity.
  • 13A to 13C are diagrams illustrating various aberrations of the variable magnification optical system according to Example 2 when focused on an object at infinity in the first telephoto end state.
  • 13A to 13C are diagrams illustrating various aberrations occurring when the variable magnification optical system according to Example 2 is in the second telephoto end state and focused on an object at infinity.
  • FIG. 13 is a diagram showing a lens configuration of a variable magnification optical system according to a third example.
  • FIG. 13 is a schematic diagram showing a lens position control mechanism according to a third embodiment.
  • 13A to 13C are diagrams illustrating various aberrations when the variable magnification optical system according to Example 3 is in the wide-angle end state and focused on an object at infinity.
  • 13A to 13C are diagrams illustrating various aberrations occurring when the variable magnification optical system according to Example 3 is in the first telephoto end state and focused on an object at infinity.
  • 13A to 13C are diagrams illustrating various aberrations occurring when the variable magnification optical system according to Example 3 is in the second telephoto end state and focused on an object at infinity.
  • FIG. 1 is a diagram showing the configuration of a camera equipped with a variable magnification optical system according to each embodiment.
  • 4 is a flowchart showing a method for manufacturing the variable magnification optical system according to the first embodiment.
  • 10 is a flowchart showing a method for manufacturing a variable magnification optical system according to a second embodiment.
  • this camera 1 is composed of a body 2 and a photographing lens 3 attached to the body 2.
  • the body 2 comprises an image sensor 4, a body control unit (not shown) that controls the operation of the digital camera, and an LCD screen 5.
  • the photographing lens 3 comprises a variable magnification optical system ZL consisting of multiple lens groups, and a lens position control mechanism (not shown) that controls the position of each lens group.
  • variable magnification optical system ZL of the photographing lens 3 Light from the subject is collected by the variable magnification optical system ZL of the photographing lens 3 and reaches the image plane I of the image sensor 4.
  • the light from the subject that reaches the image plane I is photoelectrically converted by the image sensor 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 LCD screen 5 in response to a user's operation.
  • this camera may be either a mirrorless camera or a single-lens reflex camera with a quick-return mirror.
  • the variable magnification optical system ZL shown in Figure 16 is a schematic representation of the variable magnification optical system provided in the photographing lens 3, and the lens configuration of the variable magnification optical system ZL is not limited to this configuration.
  • variable magnification optical system ZL(1) as an example of the variable magnification optical system (zoom lens) ZL according to the first embodiment is composed of 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 rear group GR having at least five lens groups, which are arranged in order from the object side along the optical axis.
  • N1 is an integer equal to or greater than 3
  • N2 is a positive integer less than N1.
  • variable magnification optical system ZL satisfies the following conditional expressions (1) and (2). 0.10 ⁇ MB/MA ⁇ 2.00 ... (1) ft1/ft2 ⁇ 0.95 ... (2)
  • MA the movement amount of the lens group having the largest movement amount when changing magnification from the wide-angle end state to the first telephoto end state
  • MB the movement amount of the lens group having the largest movement amount when changing magnification from the first telephoto end state to the second telephoto end state
  • ft1 the focal length of the variable magnification optical system ZL in the first telephoto end state
  • ft2 the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • variable power optical system that is small yet bright and has good optical performance
  • an optical device equipped with this variable power optical system The variable power ratio (telephoto magnification) in the second telephoto state is greater than the variable power ratio (telephoto magnification) in the first telephoto state.
  • the telephoto magnification can be increased. This provides the same effect as using a teleconverter in a so-called interchangeable lens camera. The same is true for the second and third embodiments.
  • Magnification change from the wide-angle end state (W) through the intermediate focus state (M) to the first telephoto end state (T1) continuously changes the focal length of the entire optical system while the image is formed on the same plane.
  • the magnification is controlled so that the focal length state is appropriate for any state from the wide-angle end state (W) to the first telephoto end state (T1).
  • magnification change (switching) from the first telephoto end state (T1) to the second telephoto end state (T2) does not require a continuous change in focal length, and it is sufficient to be able to focus and form an image at least in the first telephoto end state (T1) and the second telephoto end state (T2), and no imaging performance is required between them.
  • the change in magnification from the first telephoto end state (T1) to the second telephoto end state (T2) does not need to be controlled continuously like the change in magnification from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (intermittent, discrete).
  • the focal length can be increased from the first telephoto end state (T1) to the second telephoto end state (T2) without the need to attach a teleconverter while keeping the same optical system.
  • T1 first telephoto end state
  • T2 second telephoto end state
  • ZL(1) variable magnification optical system
  • ZL(2) variable magnification optical system
  • ZL(3) variable magnification optical system
  • Conditional formula (1) specifies the appropriate relationship between the amount of movement of the lens group having the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state and the amount of movement of the lens group having the largest amount of movement when changing magnification from the wide-angle end state to the first telephoto end state.
  • the amount of movement of the lens group when changing magnification from the wide-angle end state to the first telephoto end state indicates the difference (absolute value) between the position on the optical axis of the lens group in the first telephoto end state and the position on the optical axis of the lens group in the wide-angle end state.
  • the amount of movement of the lens group when changing magnification from the first telephoto end state to the second telephoto end state indicates the difference (absolute value) between the position on the optical axis of the lens group in the second telephoto end state and the position on the optical axis of the lens group in the first telephoto end state.
  • conditional expression (1) If the corresponding value of conditional expression (1) exceeds the upper limit, the amount of movement of the lens group that moves the largest when changing magnification from the wide-angle end state to the first telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in that lens group.
  • the upper limit of conditional expression (1) By setting the upper limit of conditional expression (1) to 1.75, 1.50, 1.25, 1.00, 0.80, 0.65, or even 0.50, the effect of the first embodiment can be made more certain.
  • conditional expression (1) falls below the lower limit, the amount of movement of the lens group that moves the largest when changing magnification from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in that lens group.
  • the lower limit of conditional expression (1) 0.10, 0.20, 0.30, or even 0.40, the effect of the first embodiment can be made more certain.
  • Conditional formula (2) specifies the appropriate relationship between the focal length of the variable magnification optical system ZL in the first telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • conditional formula (2) it is possible to obtain a variable magnification optical system that is compact yet has a high variable magnification ratio.
  • the upper limit of conditional formula (2) By setting the upper limit of conditional formula (2) to 0.90, 0.85, 0.80, or even 0.75, the effect of the first embodiment can be made more certain.
  • the lower limit of conditional formula (2) to 0.45, 0.50, or even 0.60, the effect of the first embodiment can be made more certain.
  • the rear group GR may include N2 focusing lens groups that move along the optical axis during focusing, and the N2 focusing lens groups may move along the optical axis during magnification change from the first telephoto end state to the second telephoto end state.
  • N2 is an integer equal to or greater than 2 and smaller than N1. This makes it possible to obtain a variable magnification optical system that is compact yet has a high variable magnification ratio.
  • the lens group that moves during focusing in the wide-angle end state may be referred to as the focusing lens group.
  • variable magnification optical system ZL according to the second embodiment has the same configuration as the variable magnification optical system ZL according to the first embodiment, and therefore will be described with the same reference numerals as in the first embodiment.
  • the variable magnification optical system ZL(1) as an example of the variable magnification optical system (zoom lens) ZL according to the second embodiment is composed of 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 rear group GR, arranged in order from the object side along the optical axis, as shown in FIG. 1.
  • the first lens group G1 is fixed with respect to the image surface I, and the second lens group G2 moves along the optical axis.
  • the first lens group G1 and the second lens group G2 are fixed with respect to the image plane I, and at least a portion of the rear group GR moves along the optical axis.
  • variable-magnification optical system ZL satisfies the following conditional expressions (3) and (2). 0.75 ⁇ MG2/( ⁇ f2) ⁇ 1.30 ... (3) ft1/ft2 ⁇ 0.95 ... (2) where f2 is the focal length of the second lens group G2, MG2 is the movement amount of the second lens group G2 when changing the magnification from the wide-angle end state to the first telephoto end state, ft1 is the focal length of the variable magnification optical system ZL in the first telephoto end state, and ft2 is the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • variable magnification optical system that is small yet bright and has good optical performance
  • optical device equipped with this variable magnification optical system it is possible to obtain a variable magnification optical system that is small yet bright and has good optical performance, and an optical device equipped with this variable magnification optical system.
  • the magnification change from the wide-angle end state (W) through the intermediate focus state (M) to the first telephoto end state (T1) is controlled so that the focal length state is appropriate for any state from the wide-angle end state (W) to the first telephoto end state (T1).
  • the magnification change (switching) from the first telephoto end state (T1) to the second telephoto end state (T2) is like attaching and detaching a teleconverter in a so-called interchangeable lens camera, and does not require continuous control like the magnification change from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (intermittent, discrete).
  • the focal length can be increased from the first telephoto end state (T1) to the second telephoto end state (T2) without the need to attach a teleconverter while keeping the same optical system.
  • Conditional formula (3) defines the appropriate relationship between the amount of movement of the second lens group G2 when changing magnification from the wide-angle end state to the first telephoto end state and the focal length of the second lens group G2.
  • conditional expression (3) exceeds the upper limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the second lens group G2.
  • the upper limit of conditional expression (3) is 1.20, or even 1.10, the effect of the second embodiment can be made more certain.
  • conditional expression (3) falls below the lower limit, the amount of movement of the second lens group G2 when changing magnification from the wide-angle end state to the first telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the second lens group G2.
  • the lower limit of conditional expression (3) 0.80, or even 0.85, the effect of the second embodiment can be made more certain.
  • conditional expression (2) specifies the appropriate relationship between the focal length of the variable magnification optical system ZL in the first telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • conditional expression (2) specifies the appropriate relationship between the focal length of the variable magnification optical system ZL in the first telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • the rear group GR may include at least two focusing lens groups that move along the optical axis when focusing, and the at least two focusing lens groups may move along the optical axis when changing magnification from the first telephoto end state to the second telephoto end state.
  • the lens group that moves when focusing in the wide-angle end state may be referred to as the focusing lens group.
  • variable magnification optical system ZL may satisfy the following conditional expression (4). 0.01 ⁇ Bft2/ft2 ⁇ 0.30 ... (4) where Bft2 is the back focus of the variable magnification optical system ZL in the second telephoto end state.
  • Conditional formula (4) specifies the appropriate relationship between the back focus of the variable magnification optical system ZL in the second telephoto end state and the focal length of the variable magnification optical system ZL in the second telephoto end state.
  • the rear group GR includes the final lens group GE arranged closest to the image surface, and the final lens group GE may be fixed with respect to the image surface I when changing magnification from the wide-angle end state to the first telephoto end state, and when changing magnification from the first telephoto end state to the second telephoto end state. This allows the variable magnification optical system to be made compact.
  • the third lens group G3 may be fixed with respect to the image plane I when changing magnification from the first telephoto end state to the second telephoto end state.
  • variable magnification optical system ZL may satisfy the following conditional expression (5). 0.75 ⁇ D23/( ⁇ f2) ⁇ 1.40 ... (5) where f2 is the focal length of the second lens group G2, and D23 is the change in the distance on the optical axis between the second lens group G2 and the third lens group G3 when the magnification is changed from the wide-angle end state to the first telephoto end state.
  • Conditional formula (5) specifies the appropriate relationship between the amount of change in the axial distance between the second lens group G2 and the third lens group G3 when changing magnification from the wide-angle end state to the first telephoto end state, and the focal length of the second lens group G2.
  • the amount of change in the axial distance between the second lens group G2 and the third lens group G3 when changing magnification from the wide-angle end state to the first telephoto end state indicates the difference (absolute value) between the axial distance between the second lens group G2 and the third lens group G3 in the first telephoto end state and the axial distance between the second lens group G2 and the third lens group G3 in the wide-angle end state.
  • conditional expression (5) If the corresponding value of conditional expression (5) exceeds the upper limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct the spherical aberration, coma, and field curvature that occur in the second lens group G2.
  • the upper limit of conditional expression (5) By setting the upper limit of conditional expression (5) to 1.30, or even 1.25, the effects of each embodiment can be made more certain.
  • conditional formula (5) falls below the lower limit, the amount of change in the axial distance between the second lens group G2 and the third lens group G3 when changing magnification from the wide-angle end state to the first telephoto end state becomes small, and the refractive power of the second lens group G2 needs to be increased, making it difficult to correct spherical aberration and coma aberration.
  • the lower limit of conditional formula (5) 0.80, or even 0.85, the effects of each embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (6). 0.45 ⁇ D23/f3 ⁇ 1.00 ... (6) where f3 is the focal length of the third lens group G3, and D23 is the change in the distance on the optical axis between the second lens group G2 and the third lens group G3 when the magnification is changed from the wide-angle end state to the first telephoto end state.
  • Conditional formula (6) specifies the appropriate relationship between the amount of change in the axial distance between the second lens group G2 and the third lens group G3 when changing magnification from the wide-angle end state to the first telephoto end state, and the focal length of the third lens group G3.
  • conditional expression (6) exceeds the upper limit, the refractive power of the third lens group G3 becomes strong, making it difficult to correct the spherical aberration and coma aberration that occur in the third lens group G3.
  • conditional formula (6) falls below the lower limit, the amount of change in the axial distance between the second lens group G2 and the third lens group G3 when changing magnification from the wide-angle end state to the first telephoto end state becomes small, and the refractive power of the second lens group G2 needs to be increased, making it difficult to correct spherical aberration and coma aberration.
  • the lower limit of conditional formula (6) By setting the lower limit of conditional formula (6) to 0.50, or even 0.60, the effects of each embodiment can be made more certain.
  • the rear group GR includes at least two focusing lens groups that move along the optical axis during focusing, and may satisfy the following conditional expression (7): 0 ⁇ MF1w/MF1t ⁇ 1.00 ... (7)
  • MF1w is the amount of movement of the first focusing lens group GF1, which is disposed closest to the object side among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state.
  • MF1t is the amount of movement of the first focusing lens group GF1 when changing magnification from the first telephoto end state to the second telephoto end state.
  • Conditional formula (7) specifies the appropriate relationship between the amount of movement of the first focusing lens group GF1 when changing magnification from the wide-angle end state to the first telephoto end state, and the amount of movement of the first focusing lens group GF1 when changing magnification from the first telephoto end state to the second telephoto end state.
  • conditional expression (7) If the corresponding value of conditional expression (7) exceeds the upper limit, the amount of movement of the first focusing lens group GF1 during zooming from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration and field curvature that occur in the first focusing lens group GF1.
  • the upper limit of conditional expression (7) By setting the upper limit of conditional expression (7) to 0.80, or even 0.60, the effects of each embodiment can be made more certain.
  • conditional formula (7) falls below the lower limit, the amount of movement of the first focusing lens group GF1 when changing magnification from the wide-angle end state to the first telephoto end state becomes small, making it difficult to correct the spherical aberration and field curvature that occur in the first focusing lens group GF1.
  • the lower limit of conditional formula (7) to 0.002, 0.10, or even 0.20, the effects of each embodiment can be made more certain.
  • the rear group GR includes at least two focusing lens groups that move along the optical axis during focusing, and may satisfy the following conditional expression (8): 0.05 ⁇ MF2w/MF2t ⁇ 10.00 ... (8) where MF2w is the amount of movement of the second focusing lens group GF2, which is the second lens group from the object side among the at least two focusing lens groups, when changing magnification from the wide-angle end state to the first telephoto end state. MF2t is the amount of movement of the second focusing lens group GF2 when changing magnification from the first telephoto end state to the second telephoto end state.
  • Conditional formula (8) specifies the appropriate relationship between the amount of movement of the second focusing lens group GF2 when changing magnification from the wide-angle end state to the first telephoto end state, and the amount of movement of the second focusing lens group GF2 when changing magnification from the first telephoto end state to the second telephoto end state.
  • conditional expression (8) exceeds the upper limit, the amount of movement of the second focusing lens group GF2 during zooming from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration and field curvature that occur in the second focusing lens group GF2.
  • the upper limit of conditional expression (8) By setting the upper limit of conditional expression (8) to 8.00, or even 6.00, the effects of each embodiment can be made more certain.
  • conditional expression (8) falls below the lower limit, the amount of movement of the second focusing lens group GF2 when changing magnification from the wide-angle end state to the first telephoto end state becomes small, making it difficult to correct the spherical aberration and field curvature that occur in the second focusing lens group GF2.
  • variable magnification optical system ZL may satisfy the following conditional expression (9). 0.01 ⁇ MC/MB ⁇ 2.00 ... (9) Where MB is the amount of movement of the lens group having the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state, and MC is the amount of movement of the lens group having the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.
  • Conditional formula (9) specifies the appropriate relationship between the amount of movement of the lens group that moves the largest amount when changing magnification from the first telephoto end state to the second telephoto end state, and the amount of movement of the lens group that moves the smallest amount when changing magnification from the first telephoto end state to the second telephoto end state.
  • conditional expression (9) exceeds the upper limit, the movement amount of the lens group that moves the largest when changing magnification from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in that lens group.
  • the upper limit of conditional expression (9) is 1.20, 1.10, 1.00, 0.85, or even 0.75, the effects of each embodiment can be made more certain.
  • conditional expression (9) falls below the lower limit, the movement amount of the lens group that moves the least when changing magnification from the first telephoto end state to the second telephoto end state becomes small, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in that lens group.
  • variable magnification optical system ZL may satisfy the following conditional expression (10). 0.10 ⁇ Bft2/MB ⁇ 5.00 ... (10) where MB is the movement amount of the lens group that moves the largest amount when the magnification is changed from the first telephoto end state to the second telephoto end state, and Bft2 is the back focus of the variable magnification optical system ZL in the second telephoto end state.
  • Conditional formula (10) specifies the appropriate relationship between the back focus of the variable magnification optical system ZL in the second telephoto end state and the amount of movement of the lens group that moves the largest amount when changing magnification from the first telephoto end state to the second telephoto end state.
  • conditional formula (10) it is possible to obtain a variable magnification optical system that is small, yet bright and has good optical performance.
  • the upper limit of conditional formula (10) to 3.00, or even 1.20, the effects of each embodiment can be made more certain.
  • the lower limit of conditional formula (10) to 0.30, or even 0.60, the effects of each embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (11). 0.05 ⁇ ( ⁇ f2)/f1 ⁇ 1.00 (11) where f1 is the focal length of the first lens group G1, and f2 is the focal length of the second lens group G2.
  • Conditional formula (11) defines the appropriate relationship between the focal length of the second lens group G2 and the focal length of the first lens group G1. By satisfying conditional formula (11), spherical aberration, coma, and field curvature can be corrected satisfactorily.
  • conditional expression (11) exceeds the upper limit, the refractive power of the first lens group G1 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the first lens group G1.
  • the upper limit of conditional expression (11) is 0.80, 0.70, 0.50, 0.40, or even 0.37, the effects of each embodiment can be made more certain.
  • conditional expression (11) falls below the lower limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the second lens group G2.
  • the lower limit of conditional expression (11) is 0.10, 0.15, 0.20, 0.25, or even 0.30, the effects of each embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (12). 0.01 ⁇ Bfw/fw ⁇ 0.50 ... (12) where fw is the focal length of the variable magnification optical system ZL in the wide-angle end state, and Bfw is the back focus of the variable magnification optical system ZL in the wide-angle end state.
  • Conditional formula (12) specifies the appropriate relationship between the back focus of the variable magnification optical system ZL in the wide-angle end state and the focal length of the variable magnification optical system ZL in the wide-angle end state. By satisfying conditional formula (12), it is possible to obtain a variable magnification optical system that is small, yet bright and has good optical performance. By setting the upper limit of conditional formula (12) to 0.45, 0.40, 0.35, 0.33, 0.30, or even 0.28, the effects of each embodiment can be made more certain. In addition, by setting the lower limit of conditional formula (12) to 0.05, 0.10, or even 0.13, the effects of each embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (13). 2.00 ⁇ TLw/fw ⁇ 6.00 ... (13) where fw is the focal length of the variable magnification optical system ZL in the wide-angle end state, and TLw is the total length of the variable magnification optical system ZL in the wide-angle end state.
  • Conditional formula (13) specifies the appropriate relationship between the overall length of the variable magnification optical system ZL in the wide-angle end state and the focal length of the variable magnification optical system ZL in the wide-angle end state.
  • conditional formula (13) it is possible to obtain a variable magnification optical system that is small, yet bright and has good optical performance.
  • the upper limit of conditional formula (13) to 5.50, 5.00, 4.50, or even 4.00, the effects of each embodiment can be made more certain.
  • the lower limit of conditional formula (13) to 2.50, 2.80, 3.00, or even 3.10, the effects of each embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (14). 0.01 ⁇ ( ⁇ f2)/f3 ⁇ 2.00 ... (14) where f2 is the focal length of the second lens group G2, and f3 is the focal length of the third lens group G3.
  • Conditional formula (14) defines the appropriate relationship between the focal length of the second lens group G2 and the focal length of the third lens group G3. By satisfying conditional formula (14), spherical aberration, coma, and field curvature can be corrected satisfactorily.
  • conditional expression (14) exceeds the upper limit, the refractive power of the third lens group G3 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the third lens group G3.
  • the upper limit of conditional expression (14) is 1.80, 1.60, 1.50, 1.35, 1.10, or even 1.00, the effect of this embodiment can be made more certain.
  • conditional expression (14) falls below the lower limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the second lens group G2.
  • the lower limit of conditional expression (14) is 0.10, 0.20, 0.30, 0.35, 0.45, 0.50, or even 0.55, the effect of this embodiment can be made more certain.
  • variable magnification optical system ZL may satisfy the following conditional expression (15). 1.80 ⁇ f1/f3 ⁇ 2.50 ... (15) where f1 is the focal length of the first lens group G1, and f3 is the focal length of the third lens group G3.
  • Conditional formula (15) defines the appropriate relationship between the focal length of the first lens group G1 and the focal length of the third lens group G3. By satisfying conditional formula (15), spherical aberration, coma, and field curvature can be corrected satisfactorily.
  • conditional expression (15) exceeds the upper limit, the refractive power of the third lens group G3 becomes strong, making it difficult to correct the spherical aberration, coma, and field curvature that occur in the third lens group G3.
  • the upper limit of conditional expression (15) is 2.45, 2.40, or even 2.35, the effect of this embodiment can be made more certain.
  • conditional expression (15) falls below the lower limit, the refractive power of the first lens group G1 becomes strong, making it difficult to correct the spherical aberration, coma aberration, and field curvature that occur in the first lens group G1.
  • the rear group GR includes the final lens group GE arranged closest to the image plane, and may satisfy the following conditional expression (16). 0.01 ⁇
  • Conditional formula (16) specifies the appropriate relationship between the focal length of the lens group arranged next to the final lens group GE on the object side in the rear group GR, and the focal length of the final lens group GE. By satisfying conditional formula (16), it is possible to satisfactorily correct the curvature of field.
  • conditional expression (16) exceeds the upper limit, the refractive power of the final lens group GE becomes strong, making it difficult to correct the field curvature that occurs in the final lens group GE.
  • the upper limit of conditional expression (16) is 4.80, 4.50, 4.30, 3.50, 3.30, 3.00, 2.80, or even 2.50, the effect of this embodiment can be made more certain.
  • conditional expression (16) falls below the lower limit, the refractive power of the lens group arranged next to the object side of the final lens group GE in the rear group GR becomes strong, making it difficult to correct the coma aberration and field curvature that occur in the lens group arranged next to the object side of the final lens group GE.
  • the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (16) to 0.10, 0.20, 0.25, 0.35, 0.45, or even 0.50.
  • the rear group GR may include a final lens group GE arranged closest to the image plane, and may satisfy the following conditional expression (17). 10 ⁇ f2/fr1 ⁇ 0.75 ... (17) where f2 is the focal length of the second lens group G2, and fr1 is the focal length of the lens group arranged next to the object side of the final lens group GE in the rear group GR.
  • Conditional formula (17) specifies the appropriate relationship between the focal length of the second lens group G2 and the focal length of the lens group arranged next to the object side of the final lens group GE in the rear group GR. By satisfying conditional formula (17), coma aberration and curvature of field can be corrected satisfactorily.
  • conditional expression (17) exceeds the upper limit, the refractive power of the lens group arranged next to the object side of the final lens group GE in the rear group GR becomes strong, making it difficult to correct the coma aberration and field curvature that occur in the lens group arranged next to the object side of the final lens group GE.
  • the upper limit of conditional expression (17) By setting the upper limit of conditional expression (17) to 0.70, or even 0.68, the effect of this embodiment can be made more certain.
  • conditional expression (17) falls below the lower limit, the refractive power of the second lens group G2 becomes strong, making it difficult to correct the spherical aberration, coma, and field curvature that occur in the second lens group G2.
  • a manufacturing method of the variable magnification optical system ZL according to the first embodiment will be outlined.
  • 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 rear group GR are arranged in order from the object side along the optical axis (step ST1).
  • the interval between adjacent lens groups changes, the first lens group G1 is fixed with respect to the image surface I, and N1 lens groups move along the optical axis (step ST2).
  • the first lens group G1 is fixed with respect to the image surface I, and N2 lens groups move along the optical axis (step ST3).
  • N1 is an integer equal to or greater than 3
  • N2 is a positive integer less than N1.
  • the lenses are arranged in the lens barrel so as to satisfy at least the above conditional expressions (1) and (2) (step ST4).
  • the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, the third lens group G3 having a positive refractive power, and the rear group GR are arranged in order from the object side along the optical axis (step ST11).
  • the interval between the adjacent lens groups is changed, the first lens group G1 is fixed with respect to the image surface I, and the second lens group G2 moves along the optical axis (step ST12).
  • the first lens group G1 and the second lens group G2 are fixed with respect to the image surface I, and at least a part of the rear group GR moves along the optical axis (step ST13). Then, each lens is arranged in the lens barrel so as to satisfy at least the above conditional formula (3) and conditional formula (2) (step ST14).
  • This manufacturing method makes it possible to manufacture a variable-magnification optical system that is small, yet bright and has good optical performance.
  • FIGS 1, 6, and 11 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL ⁇ ZL(1) to ZL(3) ⁇ according to the first to third examples.
  • the arrows indicate the movement direction of each lens group when changing magnification from the wide-angle end state (W) via the intermediate focus state (M) to the first telephoto end state (T1), and from the first telephoto end state (T1) to the second telephoto end state (T2).
  • the movement direction of the focusing lens group when focusing from infinity to a close-distance object is indicated by an arrow together with the word "focus.”
  • each lens group is represented by a combination of the symbol G and a number
  • each lens is represented by a combination of the symbol L and a number.
  • the lens groups, etc. are represented using different combinations of symbols and numbers for each embodiment. Therefore, even if the same combinations of symbols and numbers are used between embodiments, this does not mean that they have the same configuration.
  • Tables 1 to 3 are shown below, with Table 1 showing data on the various elements in the first embodiment, Table 2 showing data on the second embodiment, and Table 3 showing data on the third embodiment.
  • f is the focal length of the entire lens system
  • FNO is the F-number
  • ⁇ is the half angle of view (unit: ° (degrees))
  • Y is the image height.
  • TL is the distance on the optical axis from the lens surface closest to the object in the variable magnification optical system to the lens surface closest to the image surface when focused at infinity plus Bf (back focus)
  • Bf is the distance on the optical axis from the lens surface closest to the image surface in the variable magnification optical system to the image surface when focused at infinity.
  • MA indicates the amount of movement of the lens group with the largest amount of movement when changing magnification from the wide-angle end state to the first telephoto end state.
  • MB indicates the amount of movement of the lens group with the largest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.
  • MC indicates the amount of movement of the lens group with the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.
  • MG2 indicates the amount of movement of the second lens group when changing magnification from the wide-angle end state to the first telephoto end state.
  • D23 indicates the amount of change in the distance on the optical axis between the second lens group and the third lens group when changing magnification from the wide-angle end state to the first telephoto end state.
  • MF1w indicates the amount of movement of the first focusing lens group when changing magnification from the wide-angle end state to the first telephoto end state.
  • MF1t indicates the amount of movement of the first focusing lens group when changing magnification from the first telephoto end state to the second telephoto end state.
  • MF2w indicates the amount of movement of the second focusing lens group when changing magnification from the wide-angle end state to the first telephoto end state.
  • MF2t indicates the amount of movement of the second focusing lens group when changing magnification from the first telephoto end state to the second telephoto end state.
  • magnification ratio (telephoto magnification) in the second telephoto state is greater than the magnification ratio (telephoto magnification) in the first telephoto state.
  • the telephoto magnification can be increased by switching from the first telephoto state to the second telephoto state.
  • the surface number indicates the order of the optical surfaces from the object side along the direction of light travel
  • R is the radius of curvature of each optical surface (surfaces whose center of curvature is on the image side are given a positive value)
  • D is the surface spacing which is the distance on the optical axis from each optical surface to the next optical surface (or image surface)
  • nd is the refractive index of the material of the optical component with respect to the d-line
  • ⁇ d is the Abbe number based on the d-line of the material of the optical component.
  • the " ⁇ " in the radius of curvature indicates a plane or an aperture, and (stop S) indicates the aperture stop S.
  • the refractive index of air, nd 1.00000, has been omitted. If the optical surface is aspheric, an * is added to the surface number, and the paraxial radius of curvature is shown in the column for radius of curvature R.
  • X(y) is the distance (sag amount) along the optical axis direction from the tangent plane at the apex of the aspherical surface to the position on the aspherical surface at height y
  • R is the radius of curvature of the reference sphere (paraxial radius of curvature)
  • ⁇ is the conic constant
  • Ai is the ith aspherical coefficient.
  • the second-order aspherical coefficient A2 is 0, and is omitted.
  • the [Variable Distance Data] table shows the surface spacing for surface number i, where the surface spacing in the [Lens Specifications] table is (Di).
  • the [Variable Distance Data] table also shows the surface spacing when focused at infinity and when focused at close range. D0 indicates the distance from the object to the lens surface closest to the object in the variable magnification optical system.
  • the "Lens Group Data” table shows the starting surface (the surface closest to the object) and focal length of each lens group.
  • the focal length f, radius of curvature R, surface spacing D, and other lengths are generally given in "mm" unless otherwise specified, but this is not limited to the optical system, as the same optical performance can be obtained even when proportionally enlarged or reduced.
  • Fig. 1 is a diagram showing the lens configuration of a variable magnification optical system according to the first embodiment.
  • the variable magnification optical system ZL(1) according to the first embodiment is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, an eighth lens group G8 having negative refractive power, and a ninth lens group G9 having positive refractive power.
  • the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 move along the optical axis as shown by the arrows in FIG. 1, and the spacing between adjacent lens groups changes.
  • the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G5, the seventh lens group G7, and the ninth lens group G9 are fixed with respect to the image surface I.
  • an aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S is fixed with respect to the image surface I together with the third lens group G3 during the change of magnification.
  • the sign (+) or (-) next to each lens group symbol indicates the refractive power of that lens group, and this is the same for all of the following examples.
  • the first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side.
  • the second lens group G2 is composed of, arranged in order from the object side along the optical axis, a meniscus negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a meniscus positive lens L23 with its convex surface facing the object side, and a biconcave negative lens L24.
  • the second lens group G2 is the lens group that moves the greatest amount when changing magnification from the wide-angle end state to the first telephoto end state.
  • the third lens group G3 is composed of, arranged in order from the object side along the optical axis, a meniscus-shaped positive lens L31 with its convex surface facing the object side, a meniscus-shaped positive lens L32 with its convex surface facing the object side, and a cemented positive lens formed by cementing together a meniscus-shaped negative lens L33 with its convex surface facing the object side and a meniscus-shaped positive lens L34 with its convex surface facing the object side.
  • the fourth lens group G4 is composed of, arranged in order from the object side along the optical axis, a biconcave negative lens L41, a cemented negative lens formed by cementing a biconcave negative lens L42 and a meniscus positive lens L43 with its convex surface facing the object side.
  • the fourth lens group G4 is the lens group that moves the greatest amount when changing magnification from the first telephoto end state to the second telephoto end state.
  • the fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L51, and a cemented positive lens formed by cementing a biconvex positive lens L52 and a biconcave negative lens L53.
  • the lens surface facing the object side of the positive lens L51 is aspheric.
  • the sixth lens group G6 is composed of a biconvex positive lens L61.
  • the sixth lens group G6 is the lens group that has the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.
  • the seventh lens group G7 is composed of, arranged in order from the object side along the optical axis, a meniscus positive lens L71 with its concave surface facing the object side, a meniscus negative lens L72 with its convex surface facing the object side, a cemented negative lens formed by cementing together a biconvex positive lens L73 and a biconcave negative lens L74, and a biconvex positive lens L75.
  • the lens surface facing the image surface of the meniscus negative lens L72 is aspheric.
  • the eighth lens group G8 is composed of a negative meniscus lens L81 with its concave surface facing the object side.
  • the ninth lens group G9 is composed of a negative meniscus lens L91 with its concave surface facing the object side, and a positive biconvex lens L92, arranged in order from the object side along the optical axis.
  • An image surface I is located on the image side of the ninth lens group G9.
  • the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, the eighth lens group G8, and the ninth lens group G9 constitute the rear group GR.
  • the fourth lens group G4 corresponds to the first focusing lens group GF1
  • the sixth lens group G6 corresponds to the second focusing lens group GF2.
  • the eighth lens group G8 corresponds to the third focusing lens group GF3
  • the ninth lens group G9 corresponds to the final lens group GE.
  • the first focusing lens group GF1 (fourth lens group G4) and the third focusing lens group GF3 (eighth lens group G8) move along the optical axis toward the image surface at different trajectories (movement amounts), and the second focusing lens group GF2 (sixth lens group G6) moves along the optical axis toward the object surface.
  • the first focusing lens group GF1 fourth lens group G4
  • the second focusing lens group GF2 sixth lens group G6
  • the third focusing lens group GF3 fifth lens group G8
  • the second focusing lens group GF2 (sixth lens group G6) moves toward the object side along the optical axis
  • the third focusing lens group GF3 (eighth lens group G8) moves toward the image surface side along the optical axis.
  • the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move toward the image surface side along the optical axis with different trajectories (movement amounts), and the third focusing lens group GF3 (eighth lens group G8) moves toward the object side along the optical axis.
  • the variable magnification optical system ZL(1) of the first embodiment is provided in the photographic lens 3 (see FIG. 16) attached to the body 2 of the camera 1, as described above.
  • the photographic lens 3 is also called a lens barrel.
  • the photographic lens 3 (lens barrel) has built-in first to ninth group frames H1 to H9, a fixed barrel JA, and a cam barrel JC as the lens position control mechanism CH(1) of the first embodiment.
  • the first lens group G1 is held in the first group frame H1.
  • the second lens group G2 is held in the second group frame H2.
  • the third lens group G3 is held in the third group frame H3.
  • the fourth lens group G4 is held in the fourth group frame H4.
  • the fifth lens group G5 is held in the fifth group frame H5.
  • the sixth lens group G6 is held in the sixth group frame H6.
  • the seventh lens group G7 is held in the seventh group frame H7.
  • the eighth lens group G8 is held in the eighth group frame H8.
  • a cam barrel JC is arranged on the outer periphery of the fixed barrel JA so as to be rotatable relative to the fixed barrel JA.
  • a first group frame H1 is fixed to the side of the fixed barrel JA closest to the object.
  • a ninth group frame H9 is fixed to the side of the fixed barrel JA closest to the image plane.
  • On the inside of the fixed barrel JA in order from the object side, are arranged the second group frame H2, the third group frame H3, the fourth group barrel member U4, the fifth group frame H5, the sixth group barrel member U6, the seventh group frame H7, and the eighth group barrel member U8.
  • the third group frame H3 is fixed on the inside of the fixed barrel JA.
  • the fourth group frame H4 is arranged.
  • the sixth group frame H6 is arranged on the inside of the sixth group barrel member U6, the sixth group frame H6 is arranged.
  • the eighth group frame H8 is arranged on the inside of the eighth group barrel member U8, the eighth group frame H8 is arranged. Additionally, multiple guide bars extending along the optical axis direction are provided on the inner circumference of the fixed barrel JA, and engage with the guide grooves of the corresponding lens group frames and barrel members.
  • the cam barrel JC has multiple cam grooves that engage with the cam followers of the corresponding lens group frames and barrel members.
  • a first operating ring K1 and a second operating ring K2 are provided on the outer periphery of the cam barrel JC so as to be rotatable relative to the fixed barrel JA.
  • the first operation ring K1 is a so-called zoom ring, and can be rotated by the user.
  • a first detection unit (not shown) that detects the amount of rotation of the first operation ring K1 is provided inside the first operation ring K1.
  • the first detection unit detects the rotation of the first operation ring K1, it outputs the amount of rotation and the rotation speed to a control unit (not shown) in the photographing lens 3 (lens barrel).
  • An operation switch (not shown) that is operated (e.g., pressed) to expand the rotatable range of the first operation ring K1 is provided on the outer periphery of the first operation ring K1.
  • the user can perform a magnification change operation between the wide-angle end state and the first telephoto end state by rotating the first operation ring K1 without pressing the operation switch.
  • the user can perform a magnification change operation between the wide-angle end state and the second telephoto end state by rotating the first operation ring K1 while pressing the operation switch.
  • the second operation ring K2 can be rotated by the user, and the functions operated by the rotation can be set on the body 2 of the camera 1 or the photographing lens 3.
  • the user can change optical characteristics such as the focus position, focal length, or aperture value by rotating the second operation ring K2.
  • a second detection unit (not shown) that detects the amount of rotation of the second operation ring K2 is provided on the inner diameter side of the second operation ring K2.
  • the second detection unit detects the amount of rotation and rotation speed of the second operation ring K2 and outputs it to a control unit (not shown) in the photographing lens 3 (lens barrel).
  • the control unit drives and controls motors (such as a fourth group drive motor, a sixth group drive motor, and an eighth group drive motor, which will be described later) for changing the optical characteristics according to the amount of rotation of the second operation ring K2.
  • a fourth group driving unit (not shown) is provided on the fourth group cylinder member U4.
  • the fourth group driving unit drives the fourth group frame H4 in the optical axis direction.
  • the fourth group driving unit can drive the fourth lens group G4 (first focusing lens group GF1) held in the fourth group frame H4 in the optical axis direction not only during focusing but also during magnification change from the first telephoto end state to the second telephoto end state.
  • the fourth group driving unit includes a fourth group driving motor (not shown), a fourth group lead screw (not shown), and a fourth group rack (not shown).
  • the fourth group driving motor is, for example, a stepping motor, and is fixed to the fourth group cylinder member U4.
  • the fourth group lead screw has a threaded portion and is formed in an axial shape extending in the optical axis direction, and is connected to the output shaft of the fourth group driving motor to rotate.
  • the fourth group rack is screwed into the threaded portion of the fourth group lead screw and connected to the fourth group frame H4.
  • the driving mechanism that drives the fourth group frame H4 in the optical axis direction can be changed as appropriate.
  • a sixth group drive unit (not shown) is provided on the sixth group barrel member U6.
  • the sixth group drive unit drives the sixth group frame H6 in the optical axis direction.
  • the sixth group drive unit can drive the sixth lens group G6 (second focusing lens group GF2) held in the sixth group frame H6 in the optical axis direction not only during focusing but also during magnification change from the first telephoto end state to the second telephoto end state.
  • the sixth group drive unit includes a sixth group drive motor (not shown), a sixth group lead screw (not shown), and a sixth group rack (not shown).
  • the sixth group drive motor is, for example, a stepping motor, and is fixed to the sixth group barrel member U6.
  • the sixth group lead screw has a threaded portion and is formed in an axial shape extending in the optical axis direction, and is connected to the output shaft of the sixth group drive motor to rotate.
  • the sixth group rack is screwed into the threaded portion of the sixth group lead screw and connected to the sixth group frame H6.
  • the driving mechanism that drives the sixth group frame H6 in the optical axis direction can be changed as appropriate.
  • An eighth group driving unit (not shown) is provided on the eighth group barrel member U8.
  • the eighth group driving unit drives the eighth group frame H8 in the optical axis direction.
  • the eighth group driving unit can drive the eighth lens group G8 (third focusing lens group GF3) held in the eighth group frame H8 in the optical axis direction not only during focusing but also during magnification change from the first telephoto end state to the second telephoto end state.
  • the eighth group driving unit includes an eighth group driving motor (not shown), an eighth group lead screw (not shown), and an eighth group rack (not shown).
  • the eighth group driving motor is, for example, a stepping motor, and is fixed to the eighth group barrel member U8.
  • the eighth group lead screw has a threaded portion and is formed in an axial shape extending in the optical axis direction, and is connected to the output shaft of the eighth group driving motor to rotate.
  • the eighth group rack is screwed into the threaded portion of the eighth group lead screw and connected to the eighth group frame H8.
  • the driving mechanism that drives the eighth group frame H8 in the optical axis direction can be changed as appropriate.
  • the second group frame H2, the fourth group barrel member U4, the fifth group frame H5, the sixth group barrel member U6, the seventh group frame H7, and the eighth group barrel member U8 are driven in the optical axis direction by the rotation of the cam barrel JC, which rotates by the rotation of the first operating ring K1.
  • the fourth group frame H4 is driven in the optical axis direction relative to the fourth group barrel member U4 by a fourth group drive unit (not shown) provided on the fourth group barrel member U4 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the sixth group frame H6 is also driven in the optical axis direction relative to the sixth group barrel member U6 by a sixth group drive unit (not shown) provided on the sixth group barrel member U6 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the eighth group frame H8 is also driven in the optical axis direction relative to the eighth group cylindrical member U8 by an eighth group drive unit (not shown) provided on the eighth group cylindrical member U8 in response to rotation of the first operating ring K1 or the second operating ring K2.
  • the second lens group G2, the fifth lens group G5, and the seventh lens group G7 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated.
  • the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated to instruct a focusing operation.
  • the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 are driven in the optical axis direction when changing magnification from the wide-angle end state to the first telephoto end state.
  • changing magnification from the wide-angle end state (W) through the intermediate focus state (M) to the first telephoto end state (T1) continuously changes the focal length of the entire optical system while keeping the image formed on the same plane, and control is performed to change magnification so that the focal length state is appropriate for any state from the wide-angle end state (W) to the first telephoto end state (T1).
  • the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state.
  • changing (switching) magnification from the first telephoto end state (T1) to the second telephoto end state (T2) does not require a continuous change in focal length, and it is sufficient that the image can be focused and formed at least in the first telephoto end state (T1) and the second telephoto end state (T2), and imaging performance is not required between them.
  • changing magnification from the first telephoto end state (T1) to the second telephoto end state (T2) does not require continuous control like changing magnification from the wide-angle end state (W) to the first telephoto end state (T1), and may be intermittent (intermittent, discrete). This also applies to the second and third embodiments described below.
  • the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 are driven in the optical axis direction during focusing.
  • the fourth lens group G4, the sixth lens group G6, and the eighth lens group G8 may be driven in the optical axis direction electrically, not limited to mechanically and electrically (motor drive control).
  • the second lens group G2, the fifth lens group G5, and the seventh lens group G7 may be driven in the optical axis direction electrically, not limited to mechanically.
  • Table 1 below lists the values of the parameters of the variable magnification optical system in the first embodiment.
  • FIG. 3 shows various aberration diagrams of the variable magnification optical system of the first embodiment when focusing on infinity in the wide-angle end state.
  • FIG. 4 shows various aberration diagrams of the variable magnification optical system of the first embodiment when focusing on infinity in the first telephoto end state.
  • FIG. 5 shows various aberration diagrams of the variable magnification optical system of the first embodiment when focusing on infinity in the second telephoto end state.
  • FNO indicates the F-number
  • Y indicates the image height.
  • the spherical aberration diagram shows the F-number value corresponding to the maximum aperture
  • the astigmatism diagram and the distortion aberration diagram show the maximum value of the image height
  • the coma aberration diagram shows the value of each image height.
  • the solid line indicates the sagittal image surface
  • the dashed line indicates the meridional image surface. Note that the same symbols as in this embodiment are used in the aberration diagrams of each embodiment shown below, and duplicate explanations are omitted.
  • variable magnification optical system of Example 1 has excellent imaging performance, with the various aberrations being well corrected from the wide-angle end state to the first telephoto end state and from the first telephoto end state to the second telephoto end state.
  • Fig. 6 is a diagram showing the lens configuration of the variable magnification optical system according to the second example.
  • the variable magnification optical system ZL(2) according to the second example is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having negative refractive power.
  • the first lens group G1, the second lens group G2, the third lens group G3, the fifth lens group G5, the seventh lens group G7, and the eighth lens group G8 are fixed with respect to the image surface I.
  • an aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S is fixed with respect to the image surface I together with the third lens group G3 during magnification.
  • the first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side.
  • the second lens group G2 is composed of, arranged in order from the object side along the optical axis, a meniscus negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a meniscus positive lens L23 with its convex surface facing the object side, and a biconcave negative lens L24.
  • the second lens group G2 is the lens group that moves the greatest amount when changing magnification from the wide-angle end state to the first telephoto end state.
  • the third lens group G3 is composed of, arranged in order from the object side along the optical axis, a meniscus-shaped positive lens L31 with its convex surface facing the object side, a meniscus-shaped positive lens L32 with its convex surface facing the object side, and a cemented positive lens formed by cementing together a meniscus-shaped negative lens L33 with its convex surface facing the object side and a meniscus-shaped positive lens L34 with its convex surface facing the object side.
  • the fourth lens group G4 is composed of, arranged from the object side along the optical axis, a meniscus negative lens L41 with its convex surface facing the object side, and a cemented negative lens formed by cementing together a biconcave negative lens L42 and a meniscus positive lens L43 with its convex surface facing the object side.
  • the fourth lens group G4 is the lens group that moves the greatest amount when changing magnification from the first telephoto end state to the second telephoto end state.
  • the fifth lens group G5 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L51, and a cemented positive lens formed by cementing a biconvex positive lens L52 and a biconcave negative lens L53.
  • the lens surface facing the object side of the positive lens L51 is aspheric.
  • the sixth lens group G6 is composed of a biconvex positive lens L61.
  • the sixth lens group G6 is the lens group that has the smallest amount of movement when changing magnification from the first telephoto end state to the second telephoto end state.
  • the seventh lens group G7 is composed of, arranged from the object side along the optical axis, a biconvex positive lens L71, a meniscus negative lens L72 with its convex surface facing the object side, a cemented negative lens formed by cementing together a meniscus positive lens L73 with its concave surface facing the object side and a biconcave negative lens L74, and a biconvex positive lens L75.
  • the lens surface facing the image surface of the meniscus negative lens L72 is aspheric.
  • the eighth lens group G8 is composed of a negative meniscus lens L81 with its concave surface facing the object side, and a positive biconvex lens L82, arranged in order from the object side along the optical axis.
  • An image surface I is located on the image side of the eighth lens group G8.
  • the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 constitute the rear group GR.
  • the fourth lens group G4 corresponds to the first focusing lens group GF1
  • the sixth lens group G6 corresponds to the second focusing lens group GF2.
  • the eighth lens group G8 corresponds to the final lens group GE.
  • the first focusing lens group GF1 fourth lens group G4
  • the second focusing lens group GF2 sixth lens group G6
  • the first focusing lens group GF1 fourth lens group G4
  • the second focusing lens group GF2 sixth lens group G6
  • the first telephoto end state when focusing from an object at infinity to an object at close range, only the second focusing lens group GF2 (sixth lens group G6) moves along the optical axis toward the object.
  • the first focusing lens group GF1 (fourth lens group G4) and the second focusing lens group GF2 (sixth lens group G6) move along the optical axis toward the image plane at different trajectories (movement amounts).
  • the variable magnification optical system ZL(2) according to the second embodiment is provided in the photographic lens 3 (see FIG. 16) attached to the body 2 of the camera 1, as described above.
  • the photographic lens 3 (lens barrel) incorporates the first to eighth group frames H1 to H8, a fixed barrel JA, and a cam barrel JC as the lens position control mechanism CH(2) according to the second embodiment, as shown in FIG. 7.
  • the first lens group G1 is held in the first group frame H1.
  • the second lens group G2 is held in the second group frame H2.
  • the third lens group G3 is held in the third group frame H3.
  • the fourth lens group G4 is held in the fourth group frame H4.
  • the fifth lens group G5 is held in the fifth group frame H5.
  • the sixth lens group G6 is held in the sixth group frame H6.
  • the seventh lens group G7 is held in the seventh group frame H7.
  • the eighth lens group G8 is held in the eighth group frame H8.
  • a cam barrel JC is arranged on the outer periphery of the fixed barrel JA so as to be rotatable relative to the fixed barrel JA.
  • a first group frame H1 is fixed to the fixed barrel JA on the side closest to the object.
  • An eighth group frame H8 is fixed to the fixed barrel JA on the side closest to the image plane.
  • On the inner side of the fixed barrel JA in order from the object side, a second group frame H2, a third group frame H3, a fourth group barrel member U4, a fifth group frame H5, a sixth group barrel member U6, and a seventh group frame H7 are arranged.
  • the third group frame H3 is fixed on the inner side of the fixed barrel JA.
  • On the inner side of the fourth group barrel member U4, a fourth group frame H4 is arranged.
  • a sixth group frame H6 is arranged on the inner side of the sixth group barrel member U6, a sixth group frame H6 is arranged.
  • a number of guide bars extending along the optical axis direction are provided on the inner periphery of the fixed barrel JA, and engage with the guide grooves of the corresponding lens group frames and barrel members.
  • the cam barrel JC has multiple cam grooves that engage with the cam followers of the corresponding lens group frames and barrel members. As shown by the two-dot chain lines in FIG. 7, a first operating ring K1 and a second operating ring K2 are provided on the outer periphery of the cam barrel JC so as to be rotatable relative to the fixed barrel JA.
  • the first operating ring K1 and the second operating ring K2 have the same configuration as the first operating ring K1 and the second operating ring K2 in the first embodiment, and detailed description thereof will be omitted.
  • the fourth group cylindrical member U4 is provided with a fourth group drive unit (not shown).
  • the fourth group drive unit drives the fourth group frame H4 in the optical axis direction.
  • the sixth group cylindrical member U6 is provided with a sixth group drive unit (not shown).
  • the sixth group drive unit drives the sixth group frame H6 in the optical axis direction.
  • the fourth group drive unit and the sixth group drive unit have the same configuration as the fourth group drive unit and the sixth group drive unit in the first embodiment, and detailed description will be omitted.
  • the second group frame H2, the fourth group barrel member U4, the fifth group frame H5, the sixth group barrel member U6, and the seventh group frame H7 are driven in the optical axis direction by the rotation of the cam barrel JC, which rotates with the rotation of the first operating ring K1.
  • the fourth group frame H4 is driven in the optical axis direction relative to the fourth group barrel member U4 by a fourth group drive unit (not shown) provided on the fourth group barrel member U4 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the sixth group frame H6 is also driven in the optical axis direction relative to the sixth group barrel member U6 by a sixth group drive unit (not shown) provided on the sixth group barrel member U6 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the second lens group G2, the fifth lens group G5, and the seventh lens group G7 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated.
  • the fourth lens group G4 and the sixth lens group G6 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated to instruct a focusing operation.
  • the second lens group G2, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 are driven in the optical axis direction when changing magnification from the wide-angle end state to the first telephoto end state. Furthermore, the fourth lens group G4 and the sixth lens group G6 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state. Furthermore, the fourth lens group G4 and the sixth lens group G6 are driven in the optical axis direction when focusing. In this embodiment, the fourth lens group G4 and the sixth lens group G6 may be driven in the optical axis direction electrically, not limited to mechanically and electrically (motor drive control). The second lens group G2, the fifth lens group G5, and the seventh lens group G7 may be driven in the optical axis direction electrically, not limited to mechanically.
  • Table 2 below lists the values of the parameters of the variable magnification optical system in the second embodiment.
  • FIG. 8 is a diagram showing various aberrations when the variable magnification optical system of Example 2 is focused on infinity in the wide-angle end state.
  • FIG. 9 is a diagram showing various aberrations when the variable magnification optical system of Example 2 is focused on infinity in the first telephoto end state.
  • FIG. 10 is a diagram showing various aberrations when the variable magnification optical system of Example 2 is focused on infinity in the second telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system of Example 2 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the first telephoto end state and from the first telephoto end state to the second telephoto end state.
  • Fig. 11 is a diagram showing the lens configuration of the variable magnification optical system according to the third embodiment.
  • the variable magnification optical system ZL(3) according to the third embodiment is composed of, arranged in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having positive refractive power, an eighth lens group G8 having negative refractive power, and a ninth lens group G9 having negative refractive power.
  • the second lens group G2, the third lens group G3, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 move along the optical axis as shown by the arrows in FIG. 11, and the spacing between adjacent lens groups changes.
  • the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the sixth lens group G6, the eighth lens group G8, and the ninth lens group G9 are fixed with respect to the image surface I.
  • an aperture diaphragm S is disposed between the third lens group G3 and the fourth lens group G4, and the aperture diaphragm S is fixed with respect to the image surface I together with the fourth lens group G4 during magnification.
  • the first lens group G1 is composed of, arranged in order from the object side along the optical axis, a cemented positive lens formed by cementing together a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side.
  • the second lens group G2 is composed of, arranged in order from the object side along the optical axis, a meniscus negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a meniscus positive lens L23 with its convex surface facing the object side, and a biconcave negative lens L24.
  • the second lens group G2 is the lens group that moves the greatest amount when changing magnification from the wide-angle end state to the first telephoto end state.
  • the third lens group G3 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L31 and a meniscus positive lens L32 with its convex surface facing the object side.
  • the fourth lens group G4 is composed of a cemented negative lens in which, in order from the object side along the optical axis, a meniscus-shaped negative lens L41 with its convex surface facing the object side and a meniscus-shaped positive lens L42 with its convex surface facing the object side are cemented together.
  • the fifth lens group G5 is composed of, arranged from the object side along the optical axis, a biconcave negative lens L51, a meniscus negative lens L52 with its convex surface facing the object side, and a meniscus positive lens L53 with its convex surface facing the object side.
  • the fifth lens group G5 is the lens group that moves the greatest amount when changing magnification from the first telephoto end state to the second telephoto end state.
  • the sixth lens group G6 is composed of, arranged in order from the object side along the optical axis, a biconvex positive lens L61, a cemented positive lens formed by cementing together a meniscus negative lens L62 with its convex surface facing the object side and a biconvex positive lens L63.
  • the seventh lens group G7 is composed of a positive meniscus lens L71 with its convex surface facing the object side.
  • the seventh lens group G7 is the lens group that moves the least when changing magnification from the first telephoto end state to the second telephoto end state.
  • the eighth lens group G8 is composed of a meniscus negative lens L81 with its convex surface facing the object side, and a biconvex positive lens L82, arranged in order from the object side along the optical axis.
  • the lens surface facing the object side of the meniscus negative lens L81 is aspheric.
  • the ninth lens group G9 is composed of a meniscus negative lens L91 with its concave surface facing the object side, and a biconvex positive lens L92, arranged in order from the object side along the optical axis.
  • the lens surface facing the object side of the meniscus negative lens L91 is aspheric.
  • An image surface I is located on the image side of the ninth lens group G9.
  • the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, the eighth lens group G8, and the ninth lens group G9 constitute the rear group GR.
  • the fifth lens group G5 corresponds to the first focusing lens group GF1
  • the seventh lens group G7 corresponds to the second focusing lens group GF2.
  • the ninth lens group G9 corresponds to the final lens group GE.
  • the first focusing lens group GF1 (fifth lens group G5) and the second focusing lens group GF2 (seventh lens group G7) move along the optical axis toward the object at different trajectories (movement amounts).
  • the second telephoto end state when focusing from an object at infinity to an object at close range, only the second focusing lens group GF2 (seventh lens group G7) moves along the optical axis toward the object.
  • the first focusing lens group GF1 (fifth lens group G5) and the second focusing lens group GF2 (seventh lens group G7) move along the optical axis toward the image plane at different trajectories (movement amounts).
  • the variable magnification optical system ZL(3) of the third embodiment is provided in the photographic lens 3 (see FIG. 16) attached to the body 2 of the camera 1, as described above.
  • the photographic lens 3 (lens barrel) incorporates the first to ninth group frames H1 to H9, a fixed barrel JA, and a cam barrel JC as the lens position control mechanism CH(3) of the third embodiment, as shown diagrammatically in FIG. 12.
  • the first lens group G1 is held in the first group frame H1.
  • the second lens group G2 is held in the second group frame H2.
  • the third lens group G3 is held in the third group frame H3.
  • the fourth lens group G4 is held in the fourth group frame H4.
  • the fifth lens group G5 is held in the fifth group frame H5.
  • the sixth lens group G6 is held in the sixth group frame H6.
  • the seventh lens group G7 is held in the seventh group frame H7.
  • the eighth lens group G8 is held in the eighth group frame H8.
  • the ninth lens group G9 is held in the ninth
  • a cam barrel JC is arranged on the outer periphery of the fixed barrel JA so as to be rotatable relative to the fixed barrel JA.
  • a first group frame H1 is fixed to the fixed barrel JA on the side closest to the object.
  • a ninth group frame H9 is fixed to the fixed barrel JA on the side closest to the image plane.
  • On the inner side of the fixed barrel JA in order from the object side, a second group frame H2, a third group frame H3, a fourth group frame H4, a fifth group barrel member U5, a sixth group frame H6, a seventh group barrel member U7, and an eighth group frame H8 are arranged.
  • the fourth group frame H4 is fixed on the inner side of the fixed barrel JA.
  • a fifth group frame H5 is arranged on the inner side of the fifth group barrel member U5.
  • a seventh group frame H7 is arranged on the inner side of the seventh group barrel member U7.
  • a number of guide bars extending along the optical axis direction are provided on the inner periphery of the fixed barrel JA, and engage with the guide grooves of the corresponding lens group frames and barrel members.
  • the cam barrel JC has multiple cam grooves that engage with the cam followers of the corresponding lens group frames and barrel members. As shown by the two-dot chain lines in FIG. 2, a first operating ring K1 and a second operating ring K2 are provided on the outer periphery of the cam barrel JC so as to be rotatable relative to the fixed barrel JA.
  • the first operating ring K1 and the second operating ring K2 have the same configuration as the first operating ring K1 and the second operating ring K2 in the first embodiment, and detailed description thereof will be omitted.
  • a fifth group drive unit (not shown) is provided on the fifth group cylinder member U5.
  • the fifth group drive unit drives the fifth group frame H5 in the optical axis direction.
  • the fifth group drive unit can drive the fifth lens group G5 (first focusing lens group GF1) held in the fifth group frame H5 in the optical axis direction not only during focusing but also during magnification change from the first telephoto end state to the second telephoto end state.
  • the fifth group drive unit includes a fifth group drive motor (not shown), a fifth group lead screw (not shown), and a fifth group rack (not shown).
  • the fifth group drive motor is, for example, a stepping motor, and is fixed to the fifth group cylinder member U5.
  • the fifth group lead screw has a threaded portion and is formed in an axial shape extending in the optical axis direction, and is connected to the output shaft of the fifth group drive motor to rotate.
  • the fifth group rack is screwed into the threaded portion of the fifth group lead screw and connected to the fifth group frame H5.
  • the driving mechanism that drives the fifth group frame H5 in the optical axis direction can be changed as appropriate.
  • a seventh group driving unit (not shown) is provided on the seventh group barrel member U7.
  • the seventh group driving unit drives the seventh group frame H7 in the optical axis direction.
  • the seventh group driving unit can drive the seventh lens group G7 (second focusing lens group GF2) held in the seventh group frame H7 in the optical axis direction not only during focusing but also during magnification change from the first telephoto end state to the second telephoto end state.
  • the seventh group driving unit includes a seventh group driving motor (not shown), a seventh group lead screw (not shown), and a seventh group rack (not shown).
  • the seventh group driving motor is, for example, a stepping motor, and is fixed to the seventh group barrel member U6.
  • the seventh group lead screw has a threaded portion and is formed in an axial shape extending in the optical axis direction, and is connected to the output shaft of the seventh group driving motor to rotate.
  • the seventh group rack is screwed into the threaded portion of the seventh group lead screw and connected to the seventh group frame H7.
  • the driving mechanism that drives the seventh group frame H7 in the optical axis direction can be changed as appropriate.
  • the second group frame H2, the third group frame H3, the fifth group barrel member U5, the sixth group frame H6, the seventh group barrel member U7, and the eighth group frame H8 are driven in the optical axis direction by the rotation of the cam barrel JC, which rotates by the rotation of the first operating ring K1.
  • the fifth group frame H5 is driven in the optical axis direction relative to the fifth group barrel member U5 by a fifth group drive unit (not shown) provided on the fifth group barrel member U5 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the seventh group frame H7 is also driven in the optical axis direction relative to the seventh group barrel member U7 by a seventh group drive unit (not shown) provided on the seventh group barrel member U7 in response to the rotation of the first operating ring K1 or the second operating ring K2.
  • the second lens group G2, the third lens group G3, the sixth lens group G6, and the eighth lens group G8 are mechanically driven in the optical axis direction when the first operating ring K1 is rotated.
  • the fifth lens group G5 and the seventh lens group G7 are mechanically and electrically (motor drive control) driven in the optical axis direction when the first operating ring K1 is rotated, and are electrically driven in the optical axis direction when the second operating ring K2 is rotated to instruct a focusing operation.
  • the second lens group G2, the third lens group G3, the fifth lens group G5, the sixth lens group G6, the seventh lens group G7, and the eighth lens group G8 are driven in the optical axis direction when changing magnification from the wide-angle end state to the first telephoto end state. Furthermore, the fifth lens group G5 and the seventh lens group G7 are driven in the optical axis direction when changing magnification from the first telephoto end state to the second telephoto end state. Furthermore, the fifth lens group G5 and the seventh lens group G7 are driven in the optical axis direction when focusing. In this embodiment, the fifth lens group G5 and the seventh lens group G7 may be driven in the optical axis direction electrically, not limited to mechanically and electrically (motor drive control). The second lens group G2, the third lens group G3, the sixth lens group G6, and the eighth lens group G8 may be driven in the optical axis direction electrically, not limited to mechanically.
  • Table 3 below lists the values of the parameters of the variable magnification optical system in the third embodiment.
  • FIG. 13 is a diagram showing various aberrations when the variable magnification optical system of Example 3 is focused on infinity in the wide-angle end state.
  • FIG. 14 is a diagram showing various aberrations when the variable magnification optical system of Example 3 is focused on infinity in the first telephoto end state.
  • FIG. 15 is a diagram showing various aberrations when the variable magnification optical system of Example 3 is focused on infinity in the second telephoto end state. From each aberration diagram, it can be seen that the variable magnification optical system of Example 3 has excellent imaging performance, with various aberrations being well corrected from the wide-angle end state to the first telephoto end state and from the first telephoto end state to the second telephoto end state.
  • Conditional formula (1) 0.10 ⁇ MB/MA ⁇ 2.00
  • Condition (2) ft1/ft2 ⁇ 0.95
  • Conditional formula (3) 0.75 ⁇ MG2/( ⁇ f2) ⁇ 1.30
  • Conditional formula (4) 0.01 ⁇ Bft2/ft2 ⁇ 0.30
  • Condition (5) 0.75 ⁇ D23/( ⁇ f2) ⁇ 1.40
  • Conditional formula (6) 0.45 ⁇ D23/f3 ⁇ 1.00
  • Conditional formula (7) 0 ⁇ MF1w/MF1t ⁇ 1.00
  • Conditional formula (8) 0.05 ⁇ MF2w/MF2t ⁇ 10.00
  • Conditional formula (12) 0.01 ⁇ Bfw/fw ⁇ 0.50
  • Conditional formula (13) 2.00 ⁇
  • the above embodiments make it possible to realize a variable magnification optical system that is small, yet bright and has good optical performance.
  • variable magnification optical system of each embodiment variable magnification optical systems with other group configurations (for example, 10 groups, 11 groups, 12 groups, etc.) can also be configured.
  • a lens or lens group can be added to the variable magnification optical system of each embodiment closest to the object or closest to the image surface.
  • a lens or lens group can be added to the rear group closest to the object or closest to the image surface in the variable magnification optical system of each embodiment.
  • a lens group refers to a portion having at least one lens separated by an air gap that changes when the magnification is changed.
  • variable power optical system of each embodiment instead of the above-mentioned first to third focusing lens groups, a single lens group or multiple lens groups, or a partial lens group may be moved in the optical axis direction to serve as a focusing lens group that focuses from an object at infinity to an object at a close distance.
  • the focusing lens group can also be applied to autofocus, and is suitable for motor drive (using an ultrasonic motor, etc.) for autofocus.
  • the lens group or partial lens group may be moved so as to have a component in a direction perpendicular to the optical axis, or rotated (rocked) in a plane including the optical axis to serve as an anti-vibration lens group that corrects image blur caused by camera shake.
  • the lens surface may be spherical or flat, or aspherical.
  • a spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment, and prevents degradation of optical performance due to errors in processing and assembly adjustment. It is also preferable because there is little degradation of imaging performance even if the image plane is misaligned.
  • the aspheric surface may be any of the following: an aspheric surface created by grinding, a glass-molded aspheric surface in which glass is formed into an aspheric shape using a mold, or a composite aspheric surface in which resin is formed into an aspheric shape on the surface of glass.
  • the lens surface may also be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.
  • GRIN lens gradient index lens
  • the aperture diaphragm is preferably located between the third and fourth lens groups, but it is also possible to use the lens frame instead of a separate aperture diaphragm component.
  • Each lens surface may be coated with an anti-reflective coating that has high transmittance over a wide wavelength range to reduce flare and ghosting and achieve high-contrast optical performance.

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Abstract

L'invention concerne un système optique à grossissement variable (ZL) comprenant un premier groupe de lentilles (G1) ayant une réfringence positive, un deuxième groupe de lentilles (G2) ayant une réfringence négative, un troisième groupe de lentilles (G3) ayant une réfringence positive, et un groupe arrière (GR) : lorsque le grossissement varie d'un état d'extrémité grand angle (W) à un premier état d'extrémité téléobjectif (T1), des intervalles entre chaque groupe de lentilles adjacent sont modifiés, le premier groupe de lentilles (G1) est fixe par rapport à un plan d'image I, et N1 groupes de lentilles, où N1 est un nombre au moins égal à 3, sont déplacés le long d'un axe optique ; et lorsque le grossissement varie du premier état d'extrémité de téléobjectif (T1) à un second état d'extrémité de téléobjectif (T2), le premier groupe de lentilles G1 est fixe par rapport au plan d'image I et N2 groupes de lentilles, où N2 est un nombre inférieur à N1, sont déplacés le long de l'axe optique.
PCT/JP2023/044218 2022-12-09 2023-12-11 Système optique à grossissement variable, instrument optique et procédé de fabrication de système optique à grossissement variable WO2024122650A1 (fr)

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JP2022197186 2022-12-09
JP2022-197186 2022-12-09

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06148523A (ja) * 1992-11-06 1994-05-27 Canon Inc リヤーフォーカス式のズームレンズ
JP2009251280A (ja) * 2008-04-07 2009-10-29 Canon Inc ズームレンズ及びそれを有する撮像装置
WO2016017726A1 (fr) * 2014-07-30 2016-02-04 株式会社ニコン Système optique à puissance variable, dispositif optique, et procédé de fabrication de système optique à puissance variable

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06148523A (ja) * 1992-11-06 1994-05-27 Canon Inc リヤーフォーカス式のズームレンズ
JP2009251280A (ja) * 2008-04-07 2009-10-29 Canon Inc ズームレンズ及びそれを有する撮像装置
WO2016017726A1 (fr) * 2014-07-30 2016-02-04 株式会社ニコン Système optique à puissance variable, dispositif optique, et procédé de fabrication de système optique à puissance variable

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