Classifications

• • 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
  • G02B15/146—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 having more than five groups
  • G02B15/1461—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 having more than five groups the first group being positive
• • 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
  • 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 technology disclosed herein relates to a variable magnification optical system and an imaging device.
• the zoom lens described in International Publication No. 2014/155463 is known as a variable magnification optical system that can be used in imaging devices such as digital cameras.
• variable magnification optical systems that are compact, have a small F-number over the entire range of magnification, and maintain good optical performance over the entire range of magnification.
• the present disclosure has been made in consideration of the above circumstances, and aims to provide a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and maintains good optical performance over the entire range of magnification, and an imaging device equipped with this variable magnification optical system.
• a variable magnification optical system includes, in order from the object side to the image side, a front group, an intermediate group, and a rear group, the front group being composed of two or less lens groups having positive refractive power, the intermediate group being composed of two or less lens groups having negative refractive power, and the rear group being composed of a plurality of lens groups, and when the magnification is changed, all intervals between adjacent lens groups change, and TL is defined as the sum of the distance on the optical axis from the lens surface of the front group closest to the object side to the lens surface of the rear group closest to the image side when focused on an object at infinity at the wide-angle end, and the back focus in the air equivalent distance of the entire system.
• ft is the focal length of the entire system when focused on an object at infinity at the telephoto end
• Fnot is the maximum F-number when focused on an object at infinity at the telephoto end
• TLt is the sum of the distance on the optical axis from the lens surface of the front group closest to the object to the lens surface of the rear group closest to the image when focused on an object at infinity at the telephoto end and the back focus in air equivalent distance of the entire system when focused on an object at infinity at the telephoto end
• fw is the focal length of the entire system when focused on an object at infinity at the wide-angle end
• ⁇ t is the maximum half angle of view when focused on an object at infinity at the telephoto end
• variable magnification optical system is 5 ⁇ TLt/(ft ⁇ tan ⁇ t) ⁇ 10.5 (4) It is preferable to satisfy conditional expression (4) expressed as follows:
• variable magnification optical system of the above aspect has the following: 7 ⁇ ft/(fw ⁇ tan ⁇ w) ⁇ 12 (5) It is preferable to satisfy conditional expression (5) expressed as follows:
• variable magnification optical system is 0.43 ⁇ TLw/ft ⁇ 0.83 (1-1) 2.2 ⁇ Fnot ⁇ (TLt/ft) ⁇ 3.9 (2-1) It is preferable that conditional expressions (1-1) and (2-1) expressed by the following formulae be satisfied:
• variable magnification optical system is 3.8 ⁇ TLw/(ft ⁇ tan ⁇ t) ⁇ 8 (6) It is preferable to satisfy conditional expression (6) expressed as follows:
• variable magnification optical system of the above aspect is as follows: -2.5 ⁇ fw/Dexw ⁇ -0.91 (7) It is preferable to satisfy conditional expression (7) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.1 ⁇ DDL1STw/TLw ⁇ 0.6 (8) It is preferable to satisfy conditional expression (8) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.09 ⁇ DDL1STw/f1 ⁇ 0.6 (9) It is preferable to satisfy conditional expression (9) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 1 ⁇ DDL1STw/ ⁇ (fw ⁇ tan ⁇ w) ⁇ log(ft/fw) ⁇ 10 (10) It is preferable to satisfy conditional expression (10) expressed as follows:
• variable magnification optical system of the above aspect In a configuration in which at least one focusing group that moves along the optical axis during focusing is arranged in the variable magnification optical system of the above aspect, the focusing group having the largest absolute value of lateral magnification when focused on an object at infinity at the telephoto end is defined as the maximum focusing group, the lateral magnification of the maximum focusing group when focused on an object at infinity at the telephoto end is ⁇ foc, and the composite lateral magnification of all lenses on the image side of the maximum focusing group when focused on an object at infinity at the telephoto end is ⁇ focR, then the variable magnification optical system of the above aspect can be described as follows: 1.5 ⁇
• variable magnification optical system of the above aspect if the lateral magnification of the object-side focusing group of the two focusing groups when focused on an object at infinity at the telephoto end is ⁇ focA, the composite lateral magnification of all lenses on the image side of the object-side focusing group when focused on an object at infinity at the telephoto end is ⁇ focAR, the lateral magnification of the image-side focusing group of the two focusing groups when focused on an object at infinity at the telephoto end is ⁇ focB, and the composite lateral magnification of all lenses on the image side of the image-side focusing group when focused on an object at infinity at the telephoto end is ⁇ focBR, then the variable magnification optical system of the above aspect will be 0.1 ⁇
• variable magnification optical system of the above aspect is as follows: 1 ⁇
• variable magnification optical system has at least one focusing group that moves along the optical axis during focusing, and that the vibration isolation group is disposed closer to the object than the at least one focusing group.
• the vibration isolation group may be disposed in the middle group. Alternatively, the vibration isolation group may be disposed in the rear group.
• variable magnification optical system of the above aspect is as follows: 0.2 ⁇ DDL1STt/TLt ⁇ 0.8 (14) It is preferable to satisfy conditional expression (14) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.015 ⁇ DDL1STt/f1 ⁇ 0.3 (15) It is preferable to satisfy conditional expression (15) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 1.5 ⁇ Denw/ ⁇ (fw ⁇ tan ⁇ w) ⁇ log(ft/fw) ⁇ 8 (16) It is preferable to satisfy conditional expression (16) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 0.1 ⁇ Denw/(fw ⁇ ft) 1/2 ⁇ 0.65 (17) It is preferable to satisfy conditional expression (17) expressed as follows:
• variable magnification optical system is 0.8 ⁇ Fnot/(ft/fw) ⁇ 2 (18) It is preferable to satisfy conditional expression (18) expressed as follows:
• variable magnification optical system according to the above aspect is 0.45 ⁇ TLt/ft ⁇ 1.3 (19) It is preferable to satisfy conditional expression (19) expressed as follows:
• variable magnification optical system of the above embodiment has the following characteristics: 0.25 ⁇ Bfw/(ft ⁇ tan ⁇ t) ⁇ 1.8 (20) It is preferable to satisfy conditional expression (20) expressed as follows:
• variable magnification optical system of the above aspect can be expressed as follows: -1.6 ⁇ f1/fLn1 ⁇ -0.1 (21) It is preferable to satisfy conditional expression (21) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 1 ⁇ f1/(ft/Fnot) ⁇ 5.5 (22) It is preferable to satisfy conditional expression (22) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.5 ⁇ f1/(fw ⁇ ft) 1/2 ⁇ 3.5 (23) It is preferable to satisfy conditional expression (23) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.8 ⁇ f1/fw ⁇ 5 (24) It is preferable to satisfy conditional expression (24) expressed as follows:
• variable magnification optical system of the above aspect satisfies the following conditions: 58 ⁇ 1pave ⁇ 96 (25) It is preferable to satisfy conditional expression (25) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 0.1 ⁇ dF1/(ft/Fnot) ⁇ 0.45 (26) It is preferable to satisfy conditional expression (26) expressed as follows:
• variable magnification optical system of the above aspect has the following: 0 ⁇ EDf/TLt ⁇ 0.5 (27) It is preferable to satisfy conditional expression (27) expressed as follows:
• variable magnification optical system of the above aspect is as follows: 1 ⁇ EDf/EDr ⁇ 2.5 (28) It is preferable to satisfy conditional expression (28) expressed as follows:
• variable magnification optical system of the above aspect has the following characteristics: 0.6 ⁇ fFw/(-fMw) ⁇ 5 (29) It is preferable to satisfy conditional expression (29) expressed as follows:
• variable magnification optical system of the above aspect can be expressed as follows: 0.15 ⁇
• variable magnification optical system of the above aspect has the following characteristics: 0.7 ⁇ fw/fRw ⁇ 4 (31) It is preferable to satisfy conditional expression (31) expressed as follows:
• variable magnification optical system of the above embodiment has the following characteristics: 0.5 ⁇ ft/fRt ⁇ 6.5 (32) It is preferable to satisfy conditional expression (32) expressed as follows:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having negative refractive power, a third rear lens group having positive refractive power, a fourth rear lens group having negative refractive power, and a fifth rear lens group having negative refractive power.
• variable magnification optical system of the above aspect is as follows: 0.5 ⁇ fRA1/fRA3 ⁇ 4 (33) 0.5 ⁇ fRA2/fRA4 ⁇ 8 (34) 0.05 ⁇ fRA4/fRA5 ⁇ 3 (35) It is preferable to satisfy at least one of the conditions (33), (34), and (35) represented by the following:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having positive refractive power, a third rear lens group having negative refractive power, a fourth rear lens group having positive refractive power, and a fifth rear lens group having negative refractive power.
• the variable magnification optical system of the above aspect is: 0.1 ⁇ fRB1/fRB2 ⁇ 9 (36) 0.2 ⁇ fRB1/fRB4 ⁇ 9 (37) 0.1 ⁇ fRB3/fRB5 ⁇ 3 (38) It is preferable to satisfy at least one of the conditions (36), (37) and (38) represented by the following formula:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having a positive refractive power, a second rear lens group having a positive refractive power, and a third rear lens group having a negative refractive power.
• the variable magnification optical system of the above aspect has the following: 0.1 ⁇ fRC1/fRC2 ⁇ 2 (39) It is preferable to satisfy conditional expression (39) expressed as follows:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having positive refractive power, a third rear lens group having negative refractive power, and a fourth rear lens group having negative refractive power.
• variable magnification optical system of the above aspect is as follows: 0.2 ⁇ fRD1/fRD2 ⁇ 3.5 (40) 0.05 ⁇ fRD3/fRD4 ⁇ 2 (41) It is preferable to satisfy at least one of the conditions (40) and (41) represented by the following formula:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having negative refractive power, a third rear lens group having positive refractive power, a fourth rear lens group having negative refractive power, a fifth rear lens group having positive refractive power, and a sixth rear lens group having negative refractive power.
• the variable magnification optical system of the above aspect is as follows: 0.1 ⁇ fRE1/fRE3 ⁇ 3.5 (42) 0.1 ⁇ fRE3/fRE5 ⁇ 3.5 (43) 0.2 ⁇ fRE2/fRE4 ⁇ 15 (44) 0.05 ⁇ fRE4/fRE6 ⁇ 3 (45) It is preferable that at least one of the conditional expressions (42), (43), (44), and (45) expressed by the following formulae be satisfied:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having negative refractive power, a third rear lens group having positive refractive power, and a fourth rear lens group having negative refractive power.
• variable magnification optical system of the above aspect is as follows: 0.1 ⁇ fRF1/fRF3 ⁇ 2 (46) 0.1 ⁇ fRF2/fRF4 ⁇ 2.5 (47) It is preferable to satisfy at least one of the conditions (46) and (47) represented by the following formula:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having positive refractive power, a third rear lens group having positive refractive power, a fourth rear lens group having negative refractive power, and a fifth rear lens group having negative refractive power.
• variable magnification optical system of the above aspect is: 0.01 ⁇ fRG1/fRG2 ⁇ 1 (48) 0.01 ⁇ fRG3/fRG2 ⁇ 1 (49) 0.5 ⁇ fRG4/fRG5 ⁇ 5 (50) It is preferable to satisfy at least one of the conditions (48), (49), and (50) represented by the following formula:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having positive refractive power, a third rear lens group having negative refractive power, and a fourth rear lens group having positive refractive power.
• variable magnification optical system of the above aspect is as follows: 0.1 ⁇ fRH1/fRH2 ⁇ 2.5 (51) 0.1 ⁇ fRH2/fRH4 ⁇ 2 (52) It is preferable to satisfy at least one of the conditions (51) and (52) represented by the following formula:
• the rear group may be configured to include, in order from the object side to the image side, a first rear lens group having a positive refractive power, a second rear lens group having a negative refractive power, and a third rear lens group having a positive refractive power.
• the variable magnification optical system of the above aspect has the following: 0.1 ⁇ fRI1/fRI3 ⁇ 2 (53) It is preferable to satisfy conditional expression (53) expressed as follows:
• An imaging device includes a variable magnification optical system according to the above aspect of the present disclosure.
• the invention may also include lenses that have substantially no refractive power, optical elements other than lenses such as apertures, filters, and cover glasses, as well as mechanical parts such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.
• a group having positive refractive power means that the group as a whole has positive refractive power.
• a group having negative refractive power means that the group as a whole has negative refractive power.
• the “group” is not limited to a configuration consisting of multiple lenses, but may be a configuration consisting of only one lens.
• Composite aspherical lenses (lenses in which a lens (e.g. a spherical lens) and an aspherical film formed on the lens are integrated together to function as a single aspherical lens as a whole) are not considered cemented lenses, but are treated as a single lens.
• the radius of curvature, sign of refractive power, and surface shape of lenses including aspheric surfaces are those in the paraxial region.
• total system refers to a variable magnification optical system.
• Back focus in air-equivalent distance is the air-equivalent distance on the optical axis from the lens surface closest to the image side of the total system to the image plane.
• the "focal length” used in the conditional formula is the paraxial focal length.
• the “distance on the optical axis” used in the conditional formula is a geometric distance unless otherwise specified.
• the values used in the conditional formula are values based on the d-line when focused on an object at infinity, unless otherwise specified.
• the "d-line,” “C-line,” and “F-line” mentioned in this specification are emission lines.
• the wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line as 656.27 nm (nanometers), and the wavelength of the F-line as 486.13 nm (nanometers).
• the present disclosure makes it possible to provide a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and maintains good optical performance over the entire range of magnification, and an imaging device equipped with this variable magnification optical system.
• 1A and 1B correspond to the variable magnification optical system of Example 1, and are diagrams showing a cross-sectional view of the configuration of a variable magnification optical system according to one embodiment and a movement locus.
• FIG. 13 is a diagram for explaining symbols in a conditional expression.
• FIG. 1 is a diagram for explaining an effective diameter.
• 4A to 4C are diagrams showing various aberrations of the variable magnification optical system of Example 1.
• 11A and 11B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a second embodiment.
• 11A to 11C are diagrams showing various aberrations in the variable magnification optical system of Example 2.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a third embodiment.
• 11A to 11C are diagrams showing various aberrations in the variable magnification optical system according to Example 3.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fourth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 4.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fifth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to the fifth embodiment.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a sixth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 6.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a seventh embodiment.
• 13A to 13C are diagrams showing various aberrations of the variable magnification optical system of Example 7.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to an eighth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 8.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a ninth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system according to Example 9.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a tenth embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 10.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to an eleventh embodiment.
• 13A to 13C are diagrams showing various aberrations in the variable magnification optical system of Example 11.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twelfth embodiment of the present invention.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 12.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a thirteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 13.
• 13A and 13B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fourteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 14.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a fifteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 15.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a sixteenth embodiment of the present invention.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 16.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a seventeenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 17.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of the variable magnification optical system according to the eighteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 18.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a nineteenth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 19.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twentieth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system according to Example 20.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twenty-first embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 21.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twenty-second embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 22.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twenty-third embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 23.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of the variable magnification optical system according to the twenty-fourth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 24.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twenty-fifth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 25.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of the variable magnification optical system of Example 26.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 26.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of a variable magnification optical system according to a twenty-seventh embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 27.
• 23A and 23B are diagrams showing a cross-sectional view and a movement locus of the variable magnification optical system according to the twenty-eighth embodiment.
• 23A to 23C are diagrams showing various aberrations in the variable magnification optical system of Example 28.
• 1 is a perspective view of the front side of an imaging device according to an embodiment.
• FIG. 2 is a perspective view of the rear side of the imaging device according to the embodiment.
• FIG. 1 shows a cross-sectional view and a movement trajectory of the configuration of a variable magnification optical system according to one embodiment of the present disclosure.
• the upper row labeled "Wide” shows the wide-angle end state
• the lower row labeled “Tele” shows the telephoto end state.
• the example shown in FIG. 1 corresponds to the variable magnification optical system of Example 1 described below.
• FIG. 1 shows a state in which the lens is focused on an object at infinity, with the left side being the object side and the right side being the image side.
• FIG. 1 also shows the axial light beam and the light beam with the maximum half angle of view ⁇ w at the wide-angle end, as well as the axial light beam and the light beam with the maximum half angle of view ⁇ t at the telephoto end.
• variable magnification optical system disclosed herein comprises, in order from the object side to the image side along the optical axis Z, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF comprises two or less lens groups having positive refractive power.
• the intermediate group GM comprises two or less lens groups having negative refractive power.
• the rear group GR comprises multiple lens groups.
• the front group GF By making the front group GF a group with positive refractive power, it is possible to shorten the overall length, which is advantageous for achieving both compactness and a high zoom ratio. Also, by making the front group GF a group with positive refractive power, the height from the optical axis Z of the light rays incident on the intermediate group GM can be reduced, which is advantageous for suppressing aberration fluctuations during zooming.
• configuring the front group GF to consist of one or two lens groups with positive refractive power and configuring the intermediate group GM to consist of one or two lens groups with negative refractive power, it is advantageous for changing magnification while suppressing various aberrations. By changing the spacing between multiple groups during zooming, it is advantageous for suppressing various aberrations throughout the entire range of zooming.
• a lens group is defined as a group whose spacing in the optical axis direction between adjacent groups changes when the magnification is changed. When the magnification is changed, the spacing between adjacent lenses within a lens group does not change.
• a "lens group” is a component of a variable magnification optical system, and is a portion that includes at least one lens separated by an air gap that changes when the magnification is changed. When the magnification is changed, each lens group is moved or fixed in units.
• a “lens group” may also include components other than lenses that do not have refractive power, such as an aperture diaphragm St.
• each group of the variable magnification optical system shown in FIG. 1 is configured as follows.
• the front group GF is made up of one lens group consisting of three lenses.
• the middle group GM is made up of one lens group consisting of three lenses.
• the rear group GR is made up of five lens groups, in order from the object side to the image side: the first subsequent lens group GR1 consisting of an aperture stop St and one lens, the second subsequent lens group GR2 consisting of two lenses, the third subsequent lens group GR3 consisting of five lenses, the fourth subsequent lens group GR4 consisting of one lens, and the fifth subsequent lens group GR5 consisting of two lenses.
• the aperture stop St shown in FIG. 1 does not indicate the size or shape, but indicates the position on the optical axis. If the front group GF is configured to be made up of one lens group, as in the example of FIG. 1, it is advantageous for miniaturization. If the middle group GM is configured to be made up of one lens group, it is advantageous for miniaturization.
• the front group GF, the middle group GM, the second subsequent lens group GR2, the fourth subsequent lens group GR4, and the fifth subsequent lens group GR5 move along the optical axis Z while changing the spacing between adjacent lens groups, while the first subsequent lens group GR1 and the third subsequent lens group GR3 are fixed relative to the image plane Sim.
• solid arrows indicate the general movement trajectory of each group that moves when changing magnification from the wide-angle end to the telephoto end
• dotted lines in the vertical direction indicate each group that is fixed relative to the image plane Sim when changing magnification.
• FIG. 1 shows an example in which the variable magnification optical system is a zoom lens, but the variable magnification optical system of the present disclosure may be a zoom lens or a varifocal lens.
• the variable magnification optical system of the present disclosure preferably includes at least one focusing group that moves during focusing. Focusing is performed by moving the focusing group.
• the variable magnification optical system of the example in FIG. 1 includes two focusing groups. In the example in FIG. 1, of the two focusing groups, the focusing group on the object side is made up of the second subsequent lens group GR2, and the focusing group on the image side is made up of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side.
• the horizontal arrows attached to the second subsequent lens group GR2 and the fourth subsequent lens group GR4 in FIG. 1 indicate that these are focusing groups, and indicate the directions in which they move when focusing from an object at infinity to the nearest object.
• the variable magnification optical system of the present disclosure preferably includes an anti-vibration group that moves in a direction intersecting the optical axis Z during image blur correction.
• Image blur correction is performed by the movement of the anti-vibration group.
• the anti-vibration group is made up of the middle group GM. Both the upward arrow above the middle group GM in the Wide view of FIG. 1 and the downward arrow below the middle group GM in the Tele view of FIG. 1 indicate that the middle group GM is the anti-vibration group.
• vibration-reduction group it is preferable to place the vibration-reduction group closer to the image side than the front group GF. This is advantageous for making the vibration-reduction group more compact.
• variable magnification optical system includes an anti-vibration group and at least one focusing group
• the anti-vibration group is arranged closer to the object than at least one focusing group.
• the amount of aberration fluctuation during image blur correction varies depending on the position of the object to be focused, but by arranging the anti-vibration group closer to the object than the focusing group, it is possible to suppress the difference in the amount of aberration fluctuation during image blur correction for each position of the object to be focused.
• a variable magnification optical system includes an anti-vibration group and multiple focusing groups, it is preferable that the anti-vibration group is arranged closer to the object than all of the focusing groups in order to obtain the above effect more significantly.
• the vibration-reduction group may be arranged in the middle group GM. In this case, the amount of movement of the vibration-reduction group during image blur correction can be reduced.
• the vibration-reduction group may be arranged in the rear group GR. In this case, the diameter of the movement mechanism for the vibration-reduction group can be reduced, which is advantageous for miniaturization.
• variable magnification optical system of the present disclosure will also be simply referred to as the "variable magnification optical system.”
• variable magnification optical system satisfies the following conditional expression (1).
• TLw is the sum of the distance on the optical axis from the lens surface of the front group GF closest to the object to the lens surface of the rear group GR closest to the image when focused on an object at infinity at the wide-angle end, and the back focus in the air equivalent distance of the entire system.
• ft is the focal length of the entire system when focused on an object at infinity at the telephoto end.
• TLw is the total length when focused on an object at infinity at the wide-angle end.
• variable magnification optical system satisfies the following condition (1-1). 0.43 ⁇ TLw/ft ⁇ 0.83 (1-1)
• Figure 2 shows a cross-sectional view of the variable magnification optical system of Figure 1, and shows the total length TLw of this variable magnification optical system as an example.
• the upper row labeled “Wide” shows the wide-angle end state
• the lower row labeled “Tele” shows the telephoto end state.
• variable magnification optical system satisfies the following conditional expression (2).
• the maximum F-number when focused on an object at infinity at the telephoto end is Fnot.
• the sum of the distance on the optical axis from the lens surface closest to the object of the front group GF to the lens surface closest to the image of the rear group GR when focused on an object at infinity at the telephoto end and the back focus in air equivalent distance of the entire system is TLt.
• TLt is the total length when focused on an object at infinity at the telephoto end. As an example, the above total length TLt is shown in FIG. 2.
• conditional expression (2) By making sure that the corresponding value of conditional expression (2) is not equal to or less than the lower limit, it is easy to suppress various aberrations in the entire range of variable magnification. By making sure that the corresponding value of conditional expression (2) is not equal to or more than the upper limit, it is advantageous to reduce the total length while reducing the F-number at the telephoto end. 2.2 ⁇ Fnot ⁇ (TLt/ft) ⁇ 4.5 (2)
• variable magnification optical system satisfies the following condition (2-1). 2.2 ⁇ Fnot ⁇ (TLt/ft) ⁇ 3.9 (2-1)
• variable magnification optical system satisfies the following conditional expression (3).
• fw is the focal length of the entire system when focused on an object at infinity at the wide-angle end.
• ⁇ t is the maximum half angle of view when focused on an object at infinity at the telephoto end.
• tan in conditional expression (3) is a tangent, and this notation is similar for the other conditional expressions.
• conditional expression (3) it is preferable to replace the lower limit of 2 in conditional expression (3) with any of 2.3, 2.6, 2.9, and 3.2. It is also preferable to replace the upper limit of 4.5 in conditional expression (3) with any of 4.3, 4.1, 3.9, and 3.7.
• variable magnification optical system satisfies the following conditional expression (4).
• conditional expression (4) By making the corresponding value of conditional expression (4) not equal to or less than the lower limit, the axial light beam can be gradually converged toward the image surface Sim at the telephoto end, making it easy to suppress the axial chromatic aberration that occurs when the light beam is converged.
• conditional expression (4) By making the corresponding value of conditional expression (4) not equal to or more than the upper limit, it becomes easy to shorten the overall length at the telephoto end. 5 ⁇ TLt/(ft ⁇ tan ⁇ t) ⁇ 10.5 (4)
• variable magnification optical system satisfies the following conditional expression (5).
• conditional expression (5) By making sure that the corresponding value of conditional expression (5) is not below the lower limit, the focal length at the telephoto end does not become too short, so that the value of the variable magnification optical system can be fully demonstrated, and in particular, added value as a telephoto type variable magnification optical system can be ensured.
• the variable magnification ratio does not become too high, so that the amount of movement of the lens group can be prevented from becoming excessive, which is advantageous for miniaturization of the entire optical system. 7 ⁇ ft/(fw ⁇ tan ⁇ w) ⁇ 12 (5)
• variable magnification optical system satisfies the following conditional expression (6).
• conditional expression (6) By making sure that the corresponding value of conditional expression (6) is not below the lower limit, it becomes easy to suppress various aberrations over the entire range of variable magnification.
• conditional expression (6) By making sure that the corresponding value of conditional expression (6) is not above the upper limit, it is advantageous for making the entire optical system compact.
• conditional expression (6) In order to obtain better characteristics, it is preferable to change the lower limit of conditional expression (6) from 3.8 to any of 4, 4.2, and 4.4. It is also preferable to change the upper limit of conditional expression (6) from 8 to any of 7.8, 7.6, 7.4, and 7.2.
• variable magnification optical system satisfies the following conditional expression (7).
• the distance on the optical axis from the image surface Sim to the paraxial exit pupil position Pexw in a state where an object at infinity is focused at the wide-angle end is Dexw.
• FIG. 2 shows the above-mentioned distance Dexw and the paraxial exit pupil position Pexw.
• the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image surface Sim.
• Dexw is calculated using the air conversion distance for the optical element.
• conditional expression (7) By making the corresponding value of conditional expression (7) not equal to or less than the lower limit, it is easy to shorten the total length of the optical system, which is advantageous for miniaturization. By making the corresponding value of conditional expression (7) not equal to or more than the upper limit, it is easy to reduce the angle of incidence of the off-axis chief ray to the image surface Sim, which is advantageous for ensuring the amount of peripheral light. -2.5 ⁇ fw/Dexw ⁇ -0.91 (7)
• variable magnification optical system satisfies the following conditional expression (8).
• DDL1STw the distance on the optical axis from the lens surface closest to the object side of the front group GF to the aperture stop St in a state in which the lens surface is focused on an object at infinity at the wide-angle end.
• DDL1STw the above distance DDL1STw is shown in FIG. 2.
• the distance between the aperture stop St and the lens group closest to the object side of the front group GF does not become too short, and therefore the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position does not become too short, which makes it easier to suppress aberration fluctuations during variable magnification.
• the distance between the aperture stop St and the lens group closest to the object side of the front group GF does not become too long, and therefore the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position does not become too long. This makes it possible to prevent the lens group closest to the object side in the front group GF from becoming large in diameter, which is advantageous for size reduction.
• variable magnification optical system satisfies the following conditional expression (9).
• the focal length of the lens group closest to the object side of the front group GF is f1.
• the refractive power of the lens group closest to the object side of the front group GF is not too weak, making it easy to achieve both compactness and a high variable magnification ratio.
• the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position on the wide-angle side is not too long, making it possible to suppress an increase in the diameter of the lens group closest to the object side of the front group GF, making it easy to achieve compactness.
• the refractive power of the lens group closest to the object side of the front group GF is not too strong, making it easy to achieve high performance. 0.09 ⁇ DDL1STw/f1 ⁇ 0.6 (9)
• conditional expression (9) In order to obtain better characteristics, it is preferable to change the lower limit of conditional expression (9) from 0.09 to one of 0.11 and 0.13. It is also preferable to change the upper limit of conditional expression (9) from 0.6 to one of 0.57, 0.54, and 0.51.
• variable magnification optical system satisfies the following conditional expression (10).
• conditional expression (10) By making sure that the corresponding value of conditional expression (10) is not equal to or less than the lower limit, the distance from the lens surface of the front group GF closest to the object side to the entrance pupil position on the wide-angle side does not become too short, making it easy to suppress aberration fluctuations during variable magnification.
• conditional expression (10) By making sure that the corresponding value of conditional expression (10) is not equal to or greater than the upper limit, the distance from the lens surface of the front group GF closest to the object side to the entrance pupil position on the wide-angle side does not become too long, making it possible to suppress an increase in the diameter of the lens group closest to the object side of the front group GF, making it easy to achieve a compact size.
• conditional expression (10) In order to obtain better characteristics, it is preferable to replace the lower limit of 1 in conditional expression (10) with any of 1.3, 1.6, 1.9, and 2.2. It is also preferable to replace the upper limit of 10 in conditional expression (10) with any of 9.5, 9, 8.5, and 8.
• variable magnification optical system In a configuration in which at least one focusing group that moves along the optical axis Z during focusing is disposed in the variable magnification optical system, it is preferable that the variable magnification optical system satisfies the following conditional expression (11).
• the focusing group that has the maximum absolute value of the lateral magnification when focused on an object at infinity at the telephoto end is defined as the maximum focusing group.
• the lateral magnification of the maximum focusing group when focused on an object at infinity at the telephoto end is defined as ⁇ foc.
• the combined lateral magnification of all lenses on the image side of the maximum focusing group when focused on an object at infinity at the telephoto end is defined as ⁇ focR.
• ⁇ focR The combined lateral magnification of all lenses on the image side of the maximum focusing group when focused on an object at infinity at the telephoto end.
• conditional expression (11) is not greater than the upper limit, the ratio of the movement amount of the image plane position to the unit movement amount of the focusing group does not become too large, which is advantageous for achieving both manufacturability and compactness.
• variable magnification optical system In a configuration in which only two focusing groups that move along the optical axis Z during focusing are arranged in a variable magnification optical system, it is preferable that the variable magnification optical system satisfies the following conditional expression (12).
• the lateral magnification of the object-side focusing group of the two focusing groups when it is focused on an object at infinity at the telephoto end is ⁇ focA.
• the composite lateral magnification of all lenses on the image side of the object-side focusing group when it is focused on an object at infinity at the telephoto end is ⁇ focAR.
• the lateral magnification of the image-side focusing group of the two focusing groups when it is focused on an object at infinity at the telephoto end is ⁇ focB.
• the composite lateral magnification of all lenses on the image side of the image-side focusing group when it is focused on an object at infinity at the telephoto end is ⁇ focBR.
• conditional expression (12) By ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit, the ratio of the amount of movement of the image plane position to the unit amount of movement of the image-side focusing group does not become too large, which is advantageous for achieving both manufacturability and compactness.
• variable magnification optical system satisfies the following conditional expression (13).
• the lateral magnification of the vibration-reduction group when focused on an object at infinity at the telephoto end is ⁇ OIS.
• the combined lateral magnification of all lenses on the image side of the vibration-reduction group when focused on an object at infinity at the telephoto end is ⁇ OISR.
• conditional expression (13) By making the corresponding value of conditional expression (13) not equal to or less than the lower limit, the ratio of the movement amount of the image plane position to the unit movement amount of the vibration-reduction group does not become too small, so that the movement amount of the vibration-reduction group during image blur correction does not become too large, which is advantageous for achieving both high performance and compactness.
• conditional expression (13) By making the corresponding value of conditional expression (13) not equal to or more than the upper limit, the ratio of the movement amount of the image plane position to the unit movement amount of the vibration-reduction group does not become too large, which is advantageous for achieving both manufacturability and compactness.
• variable magnification optical system preferably satisfies the following conditional expression (14).
• DDL1STt the distance on the optical axis from the lens surface closest to the object side of the front group GF to the aperture stop St in a state in which the lens surface is focused on an object at infinity at the telephoto end.
• DDL1STt the above distance DDL1STt is shown in FIG. 2.
• the distance between the aperture stop St and the lens group closest to the object side of the front group GF does not become too short, and therefore the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position does not become too short, which makes it easier to suppress aberration fluctuations during variable magnification.
• the distance between the aperture stop St and the lens group closest to the object side of the front group GF does not become too long, and therefore the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position does not become too long. This makes it easier to shorten the overall length, which is advantageous for miniaturization.
• variable magnification optical system satisfies the following conditional expression (15).
• conditional expression (15) By making the corresponding value of conditional expression (15) not equal to or less than the lower limit, the movable range during magnification change is not too short, so that a high variable magnification ratio can be easily achieved.
• the refractive power of the lens group closest to the object side of the front group GF is not too weak, so that both compactness and a high variable magnification ratio can be easily achieved.
• conditional expression (15) By making the corresponding value of conditional expression (15) not equal to or more than the upper limit, the distance between the aperture stop St and the lens group closest to the object side of the front group GF is not too long, so that the distance from the lens surface closest to the object side of the front group GF to the entrance pupil position is not too long. This makes it easy to shorten the overall length, which is advantageous for compactness.
• conditional expression (15) In order to obtain better characteristics, it is preferable to change the lower limit of conditional expression (15) from 0.015 to either 0.03 or 0.045. It is also preferable to change the upper limit of conditional expression (15) from 0.3 to either 0.25 or 0.2.
• variable magnification optical system satisfies the following conditional expression (16).
• Denw is the distance on the optical axis from the lens surface closest to the object of the front group GF to the paraxial entrance pupil position Penw in a state where an object at infinity is focused at the wide-angle end.
• FIG. 2 shows the above-mentioned distance Denw and the paraxial entrance pupil position Penw.
• conditional expression (16) By making the corresponding value of conditional expression (16) not equal to or more than the upper limit, the distance from the lens surface closest to the object of the front group GF to the entrance pupil position at the wide-angle side does not become too long, so that it is possible to suppress an increase in the diameter of the lens group closest to the object of the front group GF, and therefore it is easy to achieve a compact size.
• variable magnification optical system satisfies the following conditional expression (17).
• conditional expression (17) By ensuring that the corresponding value of conditional expression (17) is not below the lower limit, the distance from the lens surface closest to the object in the front group GF on the wide-angle side to the entrance pupil position does not become too short, making it easy to suppress aberration fluctuations during magnification.
• the corresponding value of conditional expression (17) is not above the upper limit, the distance from the lens surface closest to the object in the front group GF on the wide-angle side to the entrance pupil position does not become too long, making it possible to suppress an increase in the diameter of the lens group closest to the object in the front group GF, making it easy to achieve a compact size.
• variable magnification optical system satisfies the following conditional expression (18).
• conditional expression (18) By making sure that the corresponding value of conditional expression (18) is not equal to or less than the lower limit, it is advantageous for the size of the entire optical system to be reduced. Also, it is advantageous for suppressing various aberrations, particularly at the telephoto end. By making sure that the corresponding value of conditional expression (18) is not equal to or greater than the upper limit, it becomes easy to maintain a small F-number at the telephoto end, which is advantageous for obtaining sufficient brightness at the telephoto end. 0.8 ⁇ Fnot/(ft/fw) ⁇ 2 (18)
• variable magnification optical system satisfies the following conditional expression (19).
• conditional expression (19) By making sure that the corresponding value of conditional expression (19) is not equal to or less than the lower limit, it becomes easy to suppress various aberrations at the telephoto end.
• conditional expression (19) By making sure that the corresponding value of conditional expression (19) is not equal to or greater than the upper limit, it becomes easy to shorten the overall length at the telephoto end. 0.45 ⁇ TLt/ft ⁇ 1.3 (19)
• variable magnification optical system satisfies the following conditional expression (20).
• the back focus in the air equivalent distance of the entire system when focused on an object at infinity at the wide-angle end is designated as Bfw.
• the above-mentioned back focus Bfw is shown in FIG. 2.
• the lens group closest to the object side of the front group GF may be configured to include at least one negative lens.
• the variable magnification optical system satisfies the following conditional expression (21).
• the focal length of the negative lens closest to the object side among the negative lenses included in the lens group closest to the object side of the front group GF is fLn1.
• the refractive power of the lens group closest to the object side of the front group GF does not become too weak, making it easy to miniaturize the lens group closest to the object side of the front group GF.
• the refractive power of the lens group closest to the object side of the front group GF does not become too strong, making it easy to suppress aberration fluctuations during variable magnification.
• the refractive power of the negative lens closest to the object side is not too weak, it is easy to suppress axial chromatic aberration at the telephoto end.
• "high order" in relation to aberration means fifth order or higher. -1.6 ⁇ f1/fLn1 ⁇ -0.1 (21)
• variable magnification optical system satisfies the following conditional expression (22).
• conditional expression (22) By making sure that the corresponding value of conditional expression (22) is not below the lower limit, it is advantageous for improving performance.
• the refractive power of the lens unit closest to the object in the front group GF does not become too weak, making it easy to make the lens unit closest to the object in the front group GF compact. 1 ⁇ f1/(ft/Fnot) ⁇ 5.5 (22)
• variable magnification optical system satisfies the following conditional expression (23).
• conditional expression (23) By making sure that the corresponding value of conditional expression (23) is not below the lower limit, the refractive power of the lens group closest to the object in the front group GF does not become too strong, making it easy to suppress aberration fluctuations during magnification.
• conditional expression (23) By making sure that the corresponding value of conditional expression (23) is not above the upper limit, the refractive power of the lens group closest to the object in the front group GF does not become too weak, which is advantageous for size reduction.
• variable magnification optical system satisfies the following conditional expression (24).
• conditional expression (24) By making sure that the corresponding value of conditional expression (24) is not below the lower limit, the refractive power of the lens group closest to the object in the front group GF does not become too strong, making it easy to suppress aberration fluctuations during magnification.
• conditional expression (24) By making sure that the corresponding value of conditional expression (24) is not above the upper limit, the refractive power of the lens group closest to the object in the front group GF does not become too weak, making it easy to make the lens group closest to the object in the front group GF compact.
• the lower limit of condition (24) In order to obtain better characteristics, it is preferable to change the lower limit of condition (24) from 0.8 to either 1 or 1.2. It is also preferable to change the upper limit of condition (24) from 5 to either 4.6, 4.2, or 3.8.
• the variable magnification optical system satisfies the following conditional expression (25).
• the average value of the Abbe numbers of all the positive lenses in the lens group closest to the object side of the front group GF based on the d-line is set to ⁇ 1pave.
• the refractive power of each lens constituting the lens group closest to the object side of the front group GF is not too strong.
• the corresponding value of the conditional expression (25) it is possible to suppress the axial chromatic aberration at the telephoto end from being overcorrected.
• the variable magnification optical system satisfies the following conditional expression (26).
• the above thickness dF1 is shown in FIG. 2.
• the corresponding value of conditional expression (26) is not equal to or less than the lower limit, it is advantageous for ensuring the mechanical strength of the front group GF.
• the corresponding value of conditional expression (26) is not equal to or more than the upper limit, it is advantageous for reducing the weight of the front group GF.
• variable magnification optical system satisfies the following conditional expression (27).
• conditional expression (27) By ensuring that the corresponding value of conditional expression (27) is not below the lower limit, it is advantageous for shortening the overall length of the optical system.
• the corresponding value of conditional expression (27) is not above the upper limit, it is easy to reduce the diameter of the lens closest to the object in the front group GF. 0 ⁇ EDf/TLt ⁇ 0.5 (27)
• the "effective diameter" of a lens surface is defined as twice the distance from the intersection of the outermost ray and the lens surface to the optical axis Z, among the rays that enter the lens surface from the object side and emerge to the image side.
• “Outside” here refers to the radially outward direction centered on the optical axis Z, in other words, the side away from the optical axis Z.
• the “outermost ray” is determined taking into account the entire range of magnification.
• FIG. 3 shows an example of the effective diameter ED.
• the left side is the object side
• the right side is the image side.
• FIG. 3 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx.
• the upper ray of the off-axis light beam Xb which is the light beam Xb1
• the position of the intersection of the outermost ray and the lens surface is the position Px of the maximum effective diameter.
• FIG. 3 shows an example of the effective diameter ED.
• the left side is the object side
• the right side is the image side.
• FIG. 3 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx.
• the upper ray of the off-axis light beam Xb which is the light beam Xb1
• the position of the intersection of the outermost ray and the lens surface is the position Px of the maximum effective diameter.
• the effective diameter ED of the object-side surface of the lens Lx is twice the distance from the intersection of the object-side surface of the lens Lx and the light beam Xb1 to the optical axis Z.
• the upper ray of the off-axis light beam Xb is the light beam that passes through the outermost part, but which light beam passes through the outermost part varies depending on the optical system.
• variable magnification optical system satisfies the following conditional expression (28).
• conditional expression (28) By making the corresponding value of conditional expression (28) not smaller than the lower limit, the diameter of the lens closest to the object side of the front group GF does not become too small, making it easy to ensure the peripheral illumination ratio at the maximum image height.
• the refractive power of the lens group closest to the object side of the front group GF does not become too strong in order to reduce the diameter of the lens closest to the object side of the front group GF, making it easy to suppress aberration fluctuations during variable magnification.
• the corresponding value of conditional expression (28) By making the corresponding value of conditional expression (28) not larger than the upper limit, the diameter of the lens closest to the object side of the front group GF does not become too large, making it easy to achieve a compact system. 1 ⁇ EDf/EDr ⁇ 2.5 (28)
• variable magnification optical system satisfies the following conditional expression (29).
• the focal length of the front group GF when focused on an object at infinity at the wide-angle end is fFw.
• the focal length of the middle group GM when focused on an object at infinity at the wide-angle end is fMw.
• variable magnification optical system satisfies the following conditional expression (30).
• the distance on the optical axis between the lens group closest to the object in the front group GF and the lens group closest to the image in the middle group GM when focused on an object at infinity at the wide-angle end is dFMw.
• the distance on the optical axis between the lens group closest to the object in the front group GF and the lens group closest to the image in the middle group GM when focused on an object at infinity at the telephoto end is dFMt.
• the above-mentioned distances dFMw and dFMt are shown in FIG. 2.
• the corresponding value of the conditional expression (30) By making the corresponding value of the conditional expression (30) not equal to or less than the lower limit, the movement amount of the lens groups of the front group GF and the middle group GM during the magnification change is not too small, so that it is easy to suppress the aberration fluctuation during the magnification change.
• the corresponding value of the conditional expression (30) By making the corresponding value of the conditional expression (30) not equal to or more than the upper limit, the movement amount of the lens groups of the front group GF and the middle group GM during the magnification change is not too large, so that it is easy to make the lens compact. 0.15 ⁇
• variable magnification optical system satisfies the following conditional expression (31).
• conditional expression (31) By ensuring that the corresponding value of conditional expression (31) is not below the lower limit, it is easy to shorten the overall length of the optical system at the wide-angle end, which is advantageous for size reduction.
• conditional expression (31) By ensuring that the corresponding value of conditional expression (31) is not above the upper limit, it is advantageous for correction of spherical aberration at the wide-angle end. 0.7 ⁇ fw/fRw ⁇ 4 (31)
• variable magnification optical system satisfies the following conditional expression (32).
• conditional expression (32) By ensuring that the corresponding value of conditional expression (32) is not below the lower limit, it is easy to shorten the overall length of the optical system at the telephoto end, which is advantageous for size reduction.
• conditional expression (32) By ensuring that the corresponding value of conditional expression (32) is not above the upper limit, it is advantageous for correction of spherical aberration at the telephoto end. 0.5 ⁇ ft/fRt ⁇ 6.5 (32)
• the example shown in FIG. 1 is just one example, and various modifications are possible without departing from the spirit of the technology of this disclosure.
• the number of lens groups included in each of the front group GF, middle group GM, and rear group GR, the number of lenses included in each lens group, the number of lenses included in the focusing group, and the number of lenses included in the vibration isolation group may be different from those in the example of FIG. 1.
• the number of focusing groups included in the variable magnification optical system may be different from those in the example of FIG. 1.
• the front group GF may be configured to consist of two lens groups. This is advantageous in suppressing aberration fluctuations when changing magnification.
• the intermediate group GM may be configured to consist of two lens groups. This is advantageous in suppressing aberration fluctuations when changing magnification.
• the rear group GR may be configured to include, in order from the object side to the image side, a first subsequent lens group GR1 having positive refractive power, a second subsequent lens group GR2 having negative refractive power, a third subsequent lens group GR3 having positive refractive power, a fourth subsequent lens group GR4 having negative refractive power, and a fifth subsequent lens group GR5 having negative refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (33), (34), and (35).
• conditional expressions (33), (34), and (35) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRA1.
• the focal length of the second subsequent lens group GR2 is fRA2.
• the focal length of the third subsequent lens group GR3 is fRA3.
• the focal length of the fourth subsequent lens group GR4 is fRA4.
• the focal length of the fifth rear lens group GR5 is designated as fRA5. 0.5 ⁇ fRA1/fRA3 ⁇ 4 (33) 0.5 ⁇ fRA2/fRA4 ⁇ 8 (34) 0.05 ⁇ fRA4/fRA5 ⁇ 3 (35)
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for suppressing aberrations during zooming.
• the refractive power of the third subsequent lens group GR3 does not become too strong, which can suppress over-correction of spherical aberration at the wide-angle end.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous in preventing under-correction of aberrations during zooming.
• the refractive power of the fourth subsequent lens group GR4 does not become too strong, which can prevent over-correction of aberrations during zooming.
• the refractive power of the fifth subsequent lens group GR5 does not become too weak, which is advantageous for correcting distortion aberration.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first subsequent lens group GR1 having positive refractive power, a second subsequent lens group GR2 having positive refractive power, a third subsequent lens group GR3 having negative refractive power, a fourth subsequent lens group GR4 having positive refractive power, and a fifth subsequent lens group GR5 having negative refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (36), (37), and (38).
• conditional expressions (36), (37), and (38) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRB1.
• the focal length of the second subsequent lens group GR2 is fRB2.
• the focal length of the third subsequent lens group GR3 is fRB3.
• the focal length of the fourth subsequent lens group GR4 is fRB4.
• the focal length of the fifth rear lens group GR5 is designated as fRB5. 0.1 ⁇ fRB1/fRB2 ⁇ 9 (36) 0.2 ⁇ fRB1/fRB4 ⁇ 9 (37) 0.1 ⁇ fRB3/fRB5 ⁇ 3 (38)
• the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for correcting aberrations during zooming.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting distortion aberration.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for correcting aberration during zooming.
• conditional formula (38) By ensuring that the corresponding value of conditional formula (38) is not below the lower limit, the refractive power of the fifth subsequent lens group GR5 does not become too weak, which is advantageous for correcting distortion aberration. By ensuring that the corresponding value of conditional formula (38) is not above the upper limit, the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, and a third rear lens group GR3 having negative refractive power.
• the variable magnification optical system satisfies the following conditional expression (39).
• conditional expression (39) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRC1.
• the focal length of the second subsequent lens group GR2 is fRC2. 0.1 ⁇ fRC1/fRC2 ⁇ 2 (39)
• the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for correcting aberrations during zooming.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for suppressing spherical aberrations at the wide-angle end.
• the rear group GR may be configured to include, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, and a fourth rear lens group GR4 having negative refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (40) and (41).
• the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRD1.
• the focal length of the second subsequent lens group GR2 is fRD2.
• the focal length of the third subsequent lens group GR3 is fRD3.
• the focal length of the fourth subsequent lens group GR4 is fRD4. 0.2 ⁇ fRD1/fRD2 ⁇ 3.5 (40) 0.05 ⁇ fRD3/fRD4 ⁇ 2 (41)
• conditional expression (40) By ensuring that the corresponding value of conditional expression (40) is not below the lower limit, the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for correcting aberrations during zooming. By ensuring that the corresponding value of conditional expression (40) is not above the upper limit, the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for suppressing spherical aberrations at the wide-angle end.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting distortion aberration.
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first subsequent lens group GR1 having positive refractive power, a second subsequent lens group GR2 having negative refractive power, a third subsequent lens group GR3 having positive refractive power, a fourth subsequent lens group GR4 having negative refractive power, a fifth subsequent lens group GR5 having positive refractive power, and a sixth subsequent lens group GR6 having negative refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (42), (43), (44), and (45).
• the focal length of the first rear lens group GR1 is fRE1.
• the focal length of the second rear lens group GR2 is fRE2.
• the focal length of the third rear lens group GR3 is fRE3.
• the focal length of the fourth subsequent lens group GR4 is fRE4, the focal length of the fifth subsequent lens group GR5 is fRE5, and the focal length of the sixth subsequent lens group GR6 is fRE6.
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for correcting aberrations during zooming.
• the refractive power of the fifth subsequent lens group GR5 does not become too weak, which is advantageous for correcting distortion.
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous in preventing under-correction of aberrations during zooming.
• the refractive power of the fourth subsequent lens group GR4 does not become too strong, which can prevent over-correction of aberrations during zooming.
• conditional expression (45) By ensuring that the corresponding value of conditional expression (45) is not below the lower limit, the refractive power of the sixth subsequent lens group GR6 does not become too weak, which is advantageous for correcting distortion aberration. By ensuring that the corresponding value of conditional expression (45) is not above the upper limit, the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, and a fourth rear lens group GR4 having negative refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (46) and (47).
• the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRF1.
• the focal length of the second subsequent lens group GR2 is fRF2.
• the focal length of the third subsequent lens group GR3 is fRF3.
• the focal length of the fourth subsequent lens group GR4 is fRF4. 0.1 ⁇ fRF1/fRF3 ⁇ 2 (46) 0.1 ⁇ fRF2/fRF4 ⁇ 2.5 (47)
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for correcting aberrations during zooming.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for suppressing spherical aberrations at the wide-angle end.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting distortion aberration.
• the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first subsequent lens group GR1 having positive refractive power, a second subsequent lens group GR2 having positive refractive power, a third subsequent lens group GR3 having positive refractive power, a fourth subsequent lens group GR4 having negative refractive power, and a fifth subsequent lens group GR5 having negative refractive power.
• variable magnification optical system satisfies at least one of the following conditional expressions (48), (49), and (50).
• conditional expressions (48), (49), and (50) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRG1.
• the focal length of the second subsequent lens group GR2 is fRG2.
• the focal length of the third subsequent lens group GR3 is fRG3.
• the focal length of the fourth subsequent lens group GR4 is fRG4.
• the focal length of the fifth rear lens group GR5 is designated as fRG5. 0.01 ⁇ fRG1/fRG2 ⁇ 1 (48) 0.01 ⁇ fRG3/fRG2 ⁇ 1 (49) 0.5 ⁇ fRG4/fRG5 ⁇ 5 (50)
• conditional formula (48) By ensuring that the corresponding value of conditional formula (48) is not below the lower limit, the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end. By ensuring that the corresponding value of conditional formula (48) is not above the upper limit, the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for correcting aberrations during zooming.
• the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end.
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for correcting aberrations during zooming.
• conditional expression (49) In order to obtain better characteristics, it is preferable to change the lower limit of conditional expression (49) from 0.01 to any of 0.02 and 0.03. It is also preferable to change the upper limit of conditional expression (49) from 1 to any of 0.9, 0.8, 0.7, and 0.6.
• conditional formula (50) By ensuring that the corresponding value of conditional formula (50) is not below the lower limit, the refractive power of the fifth subsequent lens group GR5 does not become too weak, which is advantageous for correcting distortion aberration. By ensuring that the corresponding value of conditional formula (50) is not above the upper limit, the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first subsequent lens group GR1 having positive refractive power, a second subsequent lens group GR2 having positive refractive power, a third subsequent lens group GR3 having negative refractive power, and a fourth subsequent lens group GR4 having positive refractive power.
• the variable magnification optical system satisfies at least one of the following conditional expressions (51) and (52).
• conditional expressions (51) and (52) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRH1.
• the focal length of the second subsequent lens group GR2 is fRH2.
• the focal length of the fourth subsequent lens group GR4 is fRH4. 0.1 ⁇ fRH1/fRH2 ⁇ 2.5 (51) 0.1 ⁇ fRH2/fRH4 ⁇ 2 (52)
• conditional expression (51) By ensuring that the corresponding value of conditional expression (51) is not below the lower limit, the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for correcting aberrations during zooming. By ensuring that the corresponding value of conditional expression (51) is not above the upper limit, the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for suppressing spherical aberrations at the wide-angle end.
• the refractive power of the fourth subsequent lens group GR4 does not become too weak, which is advantageous for correcting distortion aberration.
• the refractive power of the second subsequent lens group GR2 does not become too weak, which is advantageous for correcting aberration during zooming.
• the rear group GR may be configured to include, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, and a third rear lens group GR3 having positive refractive power.
• the variable magnification optical system satisfies the following conditional expression (53).
• conditional expression (53) the symbols are defined as follows.
• the focal length of the first subsequent lens group GR1 is fRI1.
• the focal length of the third subsequent lens group GR3 is fRI3. 0.1 ⁇ fRI1/fRI3 ⁇ 2 (53)
• the refractive power of the third subsequent lens group GR3 does not become too weak, which is advantageous for correcting distortion.
• the refractive power of the first subsequent lens group GR1 does not become too weak, which is advantageous for suppressing spherical aberration at the wide-angle end.
• variable magnification optical system of the present disclosure comprises, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR, where the front group GF comprises two or less lens groups having positive refractive power, the intermediate group GM comprises two or less lens groups having negative refractive power, and the rear group GR comprises multiple lens groups, and when the magnification is changed, all the intervals between adjacent lens groups change, and the above conditional expressions (1), (2), and (3) are satisfied.
• variable magnification optical system of the present disclosure will be described with reference to the drawings.
• the reference symbols given to each group in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanations and drawings that would otherwise be accompanied by an increase in the number of digits in the reference symbols. Therefore, even if common reference symbols are used in drawings of different examples, this does not necessarily mean that the configuration is the same.
• Example 1 The configuration and movement locus of the variable magnification optical system of Example 1 are shown in Figure 1, and the method of illustration and the configuration are as described above, so some overlapping explanations will be omitted here.
• the variable magnification optical system of Example 1 is composed of a front group GF, an intermediate group GM, and a rear group GR, in order from the object side to the image side.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power, in order from the object side to the image side.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 1 the basic lens data is shown in Table 1, the specifications and variable surface spacing in Table 2, and the aspheric coefficients in Table 3.
• the basic lens data table is written as follows.
• the Sn column shows the surface numbers, with the surface closest to the object being surface 1 and the numbers increasing by one as they move towards the image side.
• the R column shows the radius of curvature of each surface.
• the D column shows the surface spacing on the optical axis between each surface and its adjacent surface on the image side.
• the Nd column shows the refractive index for the d line of each component.
• the ⁇ d column shows the Abbe number of each component based on the d line.
• the ED column shows the effective diameter of each lens surface.
• the sign of the radius of curvature of a surface with a convex shape facing the object side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image side is negative.
• the surface number and the word (St) are entered in the column for the surface number corresponding to the aperture stop St.
• the value in the bottom row of the D column in the table is the distance between the surface closest to the image side in the table and the image plane Sim.
• the symbol DD[ ] is used for the variable surface distance when changing magnification, and the surface number of this distance on the object side is entered in the [ ] in the surface distance column.
• Table 2 shows the zoom ratio Zr, focal length f, maximum open F-number FNo., maximum full angle of view 2 ⁇ , and variable surface spacing based on the d-line.
• the zoom ratio is synonymous with the zoom magnification.
• [°] indicates that the unit is degrees.
• the columns labeled "Wide,” “Middle,” and “Tele” show the values for the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.
• the surface numbers of the aspheric surfaces are marked with *, and the value of the paraxial radius of curvature is written in the column of the radius of curvature of the aspheric surface.
• Table 3 the row Sn shows the surface numbers of the aspheric surfaces, and the rows KA and Am show the numerical values of the aspheric coefficients for each aspheric surface.
• KA and Am are aspheric coefficients in the aspheric formula expressed by the following formula.
• Zd C ⁇ h2 / ⁇ 1+(1-KA ⁇ C2 ⁇ h2 ) 1/2 ⁇ + ⁇ Am ⁇ h m however,
• h Height (distance from optical axis Z to lens surface)
• C reciprocal of paraxial radius of curvature KA
• Am aspheric coefficients, and ⁇ in the aspheric formula represents the summation with respect to m.
• the angle unit is degrees and the length unit is millimeters, but since the optical system can be used with proportional enlargement or reduction, other appropriate units can also be used. Also, in each table below, values are listed rounded to a predetermined number of decimal places.
• Figure 4 shows each aberration diagram of the variable magnification optical system of Example 1 when focused on an object at infinity. From the left, Figure 4 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration.
• the upper row labeled “Wide” shows aberrations at the wide-angle end state
• the middle row labeled “Middle” shows aberrations at the intermediate focal length state
• the lower row labeled “Tele” shows aberrations at the telephoto end state.
• the aberrations at the d-line, C-line, and F-line are shown by solid lines, long dashed lines, and short dashed lines, respectively.
• the aberrations at the d-line in the sagittal direction are shown by solid lines, and the aberrations at the d-line in the tangential direction are shown by short dashed lines.
• the aberrations at the d-line are shown by solid lines.
• the aberrations at the C-line and F-line are shown by long dashed lines and short dashed lines, respectively.
• Example 2 The configuration and movement locus of the variable magnification optical system of Example 2 are shown in FIG. 5.
• the variable magnification optical system of Example 2 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, a fourth rear lens group GR4 having positive refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the third subsequent lens group GR3 moves toward the image side, and the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 2 the basic lens data is shown in Table 4, the specifications and variable surface spacing in Table 5, the aspheric coefficients in Table 6, and the various aberration diagrams in Figure 6.
• Example 3 The configuration and movement locus of the variable magnification optical system of Example 3 are shown in FIG. 7.
• the variable magnification optical system of Example 3 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, a fourth rear lens group GR4 having positive refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third rear lens group GR3.
• the third rear lens group GR3 moves toward the image side, and the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of the middle group GM.
• variable magnification optical system of Example 3 the basic lens data is shown in Table 7, the specifications and variable surface spacing in Table 8, the aspheric coefficients in Table 9, and the various aberration diagrams in Figure 8.
• Example 4 The configuration and movement locus of the variable magnification optical system of Example 4 are shown in FIG. 9.
• the variable magnification optical system of Example 4 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, a fourth rear lens group GR4 having positive refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the third subsequent lens group GR3 moves toward the image side, and the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 4 the basic lens data is shown in Table 10, the specifications and variable surface spacing in Table 11, the aspheric coefficients in Table 12, and the various aberration diagrams in Figure 10.
• Example 5 The configuration and movement locus of the variable magnification optical system of Example 5 are shown in FIG. 11.
• the variable magnification optical system of Example 5 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, a fourth rear lens group GR4 having positive refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the third subsequent lens group GR3 moves toward the image side, and the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 5 the basic lens data is shown in Table 13, the specifications and variable surface spacing in Table 14, the aspheric coefficients in Table 15, and the various aberration diagrams in Figure 12.
• Example 6 The configuration and movement locus of the variable magnification optical system of Example 6 are shown in FIG. 13.
• the variable magnification optical system of Example 6 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, and a third rear lens group GR3 having negative refractive power.
• variable magnification optical system When changing magnification from the wide-angle end to the telephoto end, all lens groups move while changing the distance between adjacent lens groups.
• the variable magnification optical system includes one focusing group, which is made up of the second front lens group GF2. When focusing from an object at infinity to the closest object, the second front lens group GF2 moves toward the object, and the other lens groups are fixed with respect to the image plane Sim.
• the vibration reduction group is made up of the middle group GM.
• variable magnification optical system of Example 6 the basic lens data is shown in Table 16, the specifications and variable surface spacing in Table 17, the aspheric coefficients in Table 18, and the various aberration diagrams in Figure 14.
• Example 7 The configuration and movement locus of the variable magnification optical system of Example 7 are shown in FIG. 15.
• the variable magnification optical system of Example 7 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, and a fourth rear lens group GR4 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the second front lens group GF2.
• the vibration reduction group is made up of the middle group GM.
• variable magnification optical system of Example 7 the basic lens data is shown in Table 19, the specifications and variable surface spacing in Table 20, the aspheric coefficients in Table 21, and the various aberration diagrams in Figure 16.
• Example 8 The configuration and movement locus of the variable magnification optical system of Example 8 are shown in FIG. 17.
• the variable magnification optical system of Example 8 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, a fifth rear lens group GR5 having positive refractive power, and a sixth rear lens group GR6 having negative refractive power.
• variable magnification optical system includes one focusing group, which is made up of the fourth subsequent lens group GR4.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 8 the basic lens data is shown in Table 22, the specifications and variable surface spacing in Table 23, the aspheric coefficients in Table 24, and the various aberration diagrams in Figure 18.
• Example 9 The configuration and movement locus of the variable magnification optical system of Example 9 are shown in FIG. 19.
• the variable magnification optical system of Example 9 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, a fifth rear lens group GR5 having positive refractive power, and a sixth rear lens group GR6 having negative refractive power.
• variable magnification optical system includes one focusing group, which is made up of the fourth subsequent lens group GR4.
• the vibration reduction group is made up of the middle group GM.
• variable magnification optical system of Example 9 the basic lens data is shown in Table 25, the specifications and variable surface spacing in Table 26, the aspheric coefficients in Table 27, and the various aberration diagrams in Figure 20.
• Example 10 The configuration and movement locus of the variable magnification optical system of Example 10 are shown in FIG. 21.
• the variable magnification optical system of Example 10 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, and a fourth rear lens group GR4 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the third subsequent lens group GR3 moves toward the image side, and the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 10 the basic lens data is shown in Table 28, the specifications and variable surface spacing in Table 29, the aspheric coefficients in Table 30, and the various aberration diagrams in Figure 22.
• Example 11 The configuration and movement locus of the variable magnification optical system of Example 11 are shown in FIG. 23.
• the variable magnification optical system of Example 11 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 11 the basic lens data is shown in Table 31, the specifications and variable surface spacing in Table 32, the aspheric coefficients in Table 33, and the various aberration diagrams in Figure 24.
• Example 12 The configuration and movement locus of the variable magnification optical system of Example 12 are shown in FIG. 25.
• the variable magnification optical system of Example 12 is composed of a front group GF, an intermediate group GM, and a rear group GR, in order from the object side to the image side.
• the front group GF is composed of a first front lens group GF1 having positive refractive power and a second front lens group GF2 having positive refractive power, in order from the object side to the image side.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power, in order from the object side to the image side.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the middle group GM.
• variable magnification optical system of Example 12 the basic lens data is shown in Table 34, the specifications and variable surface spacing in Table 35, the aspheric coefficients in Tables 36A and 36B, and the aberration diagrams in Figure 26.
• Example 13 The configuration and movement locus of the variable magnification optical system of Example 13 are shown in FIG. 27.
• the variable magnification optical system of Example 13 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, a fifth rear lens group GR5 having positive refractive power, and a sixth rear lens group GR6 having negative refractive power.
• variable magnification optical system includes one focusing group, which is made up of the fourth subsequent lens group GR4.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 13 the basic lens data is shown in Table 37, the specifications and variable surface spacing in Table 38, the aspheric coefficients in Table 39, and each aberration diagram in Figure 28.
• Example 14 The configuration and movement locus of the variable magnification optical system of Example 14 are shown in FIG. 29.
• the variable magnification optical system of Example 14 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of, in order from the object side to the image side, a first front lens group GF1 having positive refractive power, and a second front lens group GF2 having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• variable magnification optical system includes one focusing group, which is made up of the fourth subsequent lens group GR4.
• the vibration reduction group is made up of the middle group GM.
• variable magnification optical system of Example 14 the basic lens data is shown in Table 40, the specifications and variable surface spacing in Table 41, the aspheric coefficients in Table 42, and each aberration diagram in Figure 30.
• Example 15 The configuration and movement locus of the variable magnification optical system of Example 15 are shown in FIG. 31.
• the variable magnification optical system of Example 15 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of, in order from the object side to the image side, a first intermediate lens group GM1 having negative refractive power, and a second intermediate lens group GM2 having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, and a fourth rear lens group GR4 having negative refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the second subsequent lens group GR2.
• the vibration reduction group is made up of three lenses: the first lens, the second lens, and the third lens from the image side of the first subsequent lens group GR1.
• variable magnification optical system of Example 15 the basic lens data is shown in Table 43, the specifications and variable surface spacing in Table 44, the aspheric coefficients in Tables 45A and 45B, and the respective aberration diagrams in Figure 32.
• Example 16 The configuration and movement locus of the variable magnification optical system of Example 16 are shown in FIG. 33.
• the variable magnification optical system of Example 16 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 16 the basic lens data is shown in Table 46, the specifications and variable surface spacing in Table 47, the aspheric coefficients in Table 48, and the various aberration diagrams in Figure 34.
• Example 17 The configuration and movement locus of the variable magnification optical system of Example 17 are shown in FIG. 35.
• the variable magnification optical system of Example 17 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 17 the basic lens data is shown in Table 49, the specifications and variable surface spacing in Table 50, the aspheric coefficients in Table 51, and each aberration diagram in Figure 36.
• Example 18 The configuration and movement locus of the variable magnification optical system of Example 18 are shown in FIG. 37.
• the variable magnification optical system of Example 18 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 18 the basic lens data is shown in Table 52, the specifications and variable surface spacing in Table 53, the aspheric coefficients in Table 54, and each aberration diagram in Figure 38.
• Example 19 The configuration and movement locus of the variable magnification optical system of Example 19 are shown in FIG. 39.
• the variable magnification optical system of Example 19 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 19 the basic lens data is shown in Table 55, the specifications and variable surface spacing in Table 56, the aspheric coefficients in Table 57, and the various aberration diagrams in Figure 40.
• Example 20 The configuration and movement locus of the variable magnification optical system of Example 20 are shown in FIG. 41.
• the variable magnification optical system of Example 20 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, a fifth rear lens group GR5 having positive refractive power, and a sixth rear lens group GR6 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side is made up of the third subsequent lens group GR3, and the focusing group on the image side is made up of the fourth subsequent lens group GR4.
• the vibration reduction group is made up of three lenses: the first lens, the second lens, and the third lens from the image side of the second subsequent lens group GR2.
• variable magnification optical system of Example 20 the basic lens data is shown in Table 58, the specifications and variable surface spacing are shown in Table 59, and each aberration diagram is shown in Figure 42.
• Example 21 The configuration and movement locus of the variable magnification optical system of Example 21 are shown in FIG. 43.
• the variable magnification optical system of Example 21 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, a fourth rear lens group GR4 having positive refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the object-side focusing group is made up of the lens closest to the image in the second subsequent lens group GR2, and the image-side focusing group is made up of the third subsequent lens group GR3.
• the object-side focusing group and the image-side focusing group move toward the image side while changing the spacing between them, and the other lenses are fixed with respect to the image surface Sim.
• the vibration reduction group is made up of three lenses: the second lens, the third lens, and the fourth lens from the object side in the second subsequent lens group GR2.
• variable magnification optical system of Example 21 the basic lens data is shown in Table 60, the specifications and variable surface spacing in Table 61, the aspheric coefficients in Table 62, and each aberration diagram in Figure 44.
• Example 22 The configuration and movement locus of the variable magnification optical system of Example 22 are shown in FIG. 45.
• the variable magnification optical system of Example 22 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the object-side focusing group is made up of the third subsequent lens group GR3, and the image-side focusing group is made up of two lenses, the first lens from the object side of the fourth subsequent lens group GR4 and the second lens.
• the object-side focusing group and the image-side focusing group move toward the image side while changing the distance between them, and the other lenses are fixed with respect to the image surface Sim.
• the vibration reduction group consists of three lenses: the first lens, the second lens, and the third lens from the image side of the second subsequent lens group GR2.
• variable magnification optical system of Example 22 the basic lens data is shown in Table 63, the specifications and variable surface spacing in Table 64, the aspheric coefficients in Table 65, and each aberration diagram in Figure 46.
• Example 23 The configuration and movement locus of the variable magnification optical system of Example 23 are shown in Figure 47.
• the variable magnification optical system of Example 23 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, and a fourth rear lens group GR4 having positive refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the vibration reduction group is made up of three lenses: the first lens, the second lens, and the third lens from the object side of the first subsequent lens group GR1.
• variable magnification optical system of Example 23 the basic lens data is shown in Table 66, the specifications and variable surface spacing in Table 67, the aspheric coefficients in Table 68, and each aberration diagram in Figure 48.
• Example 24 The configuration and movement locus of the variable magnification optical system of Example 24 are shown in Figure 49.
• the variable magnification optical system of Example 24 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, and a third rear lens group GR3 having positive refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the second subsequent lens group GR2.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 24 the basic lens data is shown in Table 69, the specifications and variable surface spacing in Table 70, the aspheric coefficients in Table 71, and each aberration diagram in Figure 50.
• Example 25 The configuration and movement locus of the variable magnification optical system of Example 25 are shown in FIG. 51.
• the variable magnification optical system of Example 25 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the focusing group on the object side consists of the second subsequent lens group GR2, and the focusing group on the image side consists of the fourth subsequent lens group GR4.
• the second subsequent lens group GR2 moves toward the object side
• the fourth subsequent lens group GR4 moves toward the image side
• the other lens groups are fixed with respect to the image surface Sim.
• the vibration reduction group consists of the intermediate group GM.
• variable magnification optical system of Example 25 the basic lens data is shown in Table 72, the specifications and variable surface spacing in Table 73, the aspheric coefficients in Table 74, and each aberration diagram in Figure 52.
• Example 26 The configuration and movement locus of the variable magnification optical system of Example 26 are shown in FIG. 53.
• the variable magnification optical system of Example 26 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having positive refractive power, a fourth rear lens group GR4 having negative refractive power, and a fifth rear lens group GR5 having negative refractive power.
• the variable magnification optical system includes two focusing groups.
• the object-side focusing group is made up of the third subsequent lens group GR3, and the image-side focusing group is made up of two lenses, the first lens from the object side of the fourth subsequent lens group GR4 and the second lens.
• the object-side focusing group and the image-side focusing group move toward the image side while changing the distance between them, and the other lenses are fixed with respect to the image surface Sim.
• the vibration reduction group consists of three lenses: the first lens, the second lens, and the third lens from the image side of the second subsequent lens group GR2.
• variable magnification optical system of Example 26 the basic lens data is shown in Table 75, the specifications and variable surface spacing in Table 76, the aspheric coefficients in Table 77, and the various aberration diagrams in Figure 54.
• Example 27 The configuration and movement locus of the variable magnification optical system of Example 27 are shown in Figure 55.
• the variable magnification optical system of Example 27 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having positive refractive power, a third rear lens group GR3 having negative refractive power, and a fourth rear lens group GR4 having positive refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the third subsequent lens group GR3.
• the vibration reduction group is made up of three lenses: the first lens, the second lens, and the third lens from the object side of the first subsequent lens group GR1.
• variable magnification optical system of Example 27 the basic lens data is shown in Table 78, the specifications and variable surface spacing in Table 79, the aspheric coefficients in Table 80, and the various aberration diagrams in Figure 56.
• Example 28 The configuration and movement locus of the variable magnification optical system of Example 28 are shown in Figure 57.
• the variable magnification optical system of Example 28 is composed of, in order from the object side to the image side, a front group GF, an intermediate group GM, and a rear group GR.
• the front group GF is composed of one lens group having positive refractive power.
• the intermediate group GM is composed of one lens group having negative refractive power.
• the rear group GR is composed of, in order from the object side to the image side, a first rear lens group GR1 having positive refractive power, a second rear lens group GR2 having negative refractive power, and a third rear lens group GR3 having positive refractive power.
• the variable magnification optical system includes one focusing group, which is made up of the second subsequent lens group GR2.
• the vibration reduction group is made up of the intermediate group GM.
• variable magnification optical system of Example 28 the basic lens data is shown in Table 81, the specifications and variable surface spacing in Table 82, the aspheric coefficients in Table 83, and each aberration diagram in Figure 58.
• Tables 84 to 95 show the corresponding values of conditional expressions (1) to (53) for the variable magnification optical systems of Examples 1 to 28.
• the corresponding values of the Examples shown in Tables 84 to 95 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.
• variable magnification optical systems of Examples 1 to 28 are constructed to be compact, yet have an F-number of 4.2 or less over the entire range of magnification, realizing a small F-number. In particular, some examples have an F-number of 3 or less over the entire range of magnification. Furthermore, the variable magnification optical systems of Examples 1 to 28 maintain high optical performance with various aberrations well corrected over the entire range of magnification.
• Figs. 59 and 60 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure.
• Fig. 59 shows a perspective view of the camera 30 seen from the front side
• Fig. 60 shows a perspective view of the camera 30 seen from the rear side.
• the camera 30 is a so-called mirrorless type digital camera, to which an interchangeable lens 20 can be removably attached.
• the interchangeable lens 20 is configured to include a variable magnification optical system 1 according to an embodiment of the present disclosure housed within a lens barrel.
• Camera 30 has a camera body 31, and a shutter button 32 and a power button 33 are provided on the top surface of camera body 31.
• operation units 34, 35, and a display unit 36 are provided on the back surface of camera body 31.
• Display unit 36 is capable of displaying a captured image and an image within the angle of view before capture.
• a shooting aperture through which light from the subject is incident is provided in the center of the front of the camera body 31, and a mount 37 is provided at a position corresponding to the shooting aperture, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.
• the camera body 31 contains an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image.
• an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image.
• CMOS Complementary Metal Oxide Semiconductor
• the technology of the present disclosure has been described above using embodiments and examples, but the technology of the present disclosure is not limited to the above embodiments and examples, and various modifications are possible.
• the radius of curvature, surface spacing, refractive index, Abbe number, aspheric coefficient, etc. of each lens are not limited to the values shown in the above examples, and may take other values.
• the imaging device is not limited to the above example, and can take various forms, such as cameras other than mirrorless type, film cameras, video cameras, and security cameras.
• the lens consists of, in order from the object side to the image side, a front group, an intermediate group, and a rear group.
• the front group is composed of two or less lens groups each having a positive refractive power
• the intermediate group is composed of two or less lens groups each having a negative refractive power
• the rear group is made up of a plurality of lens groups
• the maximum F-number when the lens is focused on an object at infinity at the telephoto end is Fnot.
• TLt is the sum of the distance on the optical axis from the lens surface of the front group closest to the object side to the lens surface of the rear group closest to the image side when focused on an object at infinity at the telephoto end, and the back focus in terms of the air equivalent distance of the entire system;
• the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw.
• a variable magnification optical system which satisfies conditional expression (4) expressed by: [Additional Note 3] If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ⁇ w, 7 ⁇ ft/(fw ⁇ tan ⁇ w) ⁇ 12 (5) 3.
• variable magnification optical system which satisfies conditional expression (5) represented by: [Additional Note 4] 0.43 ⁇ TLw/ft ⁇ 0.83 (1-1) 2.2 ⁇ Fnot ⁇ (TLt/ft) ⁇ 3.9 (2-1)
• the variable magnification optical system according to any one of supplementary items 1 to 3 which satisfies the conditional expressions (1-1) and (2-1) represented by the following formula: [Additional Note 5] 3.8 ⁇ TLw/(ft ⁇ tan ⁇ t) ⁇ 8 (6)
• the distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end is Dexw.
• the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side based on the image surface.
• an optical element having no refractive power is disposed between the image surface and the paraxial exit pupil position
• when calculating Dexw for the optical element using an air-equivalent distance -2.5 ⁇ fw/Dexw ⁇ -0.91 (7)
• DDL1STw the distance on the optical axis from the lens surface of the front group closest to the object side to the aperture stop in a state in which the lens is focused on an object at infinity at the wide-angle end is denoted as DDL1STw, 0.1 ⁇ DDL1STw/TLw ⁇ 0.6
• variable magnification optical system wherein the vibration reduction group is disposed on the object side of at least one of the focusing groups.
• the vibration reduction group is disposed in the intermediate group.
• an aperture stop is disposed between the lens surface of the intermediate group closest to the image side and the lens surface of the rear group closest to the image side;
• the variable magnification optical system according to any one of supplementary items 1 to 15, which satisfies conditional expression (14) represented by: [Additional Item 17] an aperture stop is disposed between the lens surface of the intermediate group closest to the image side and the lens surface of the rear group closest to the image side; The distance on the optical axis from the lens surface of the front group closest to the object side to the aperture stop when focused on an object at infinity at the telephoto end is DDL1STt, If the focal length of the lens unit closest to the object side in the front group is f1, 0.015 ⁇ DDL1STt
• variable magnification optical system according to any one of supplementary items 1 to 19, which satisfies conditional expression (18) represented by: [Additional Item 21] 0.45 ⁇ TLt/ft ⁇ 1.3 (19)
• the lens unit closest to the object side of the front group includes at least one negative lens
• the focal length of the lens unit closest to the object side in the front group is f1
• the focal length of the negative lens closest to the object among the negative lenses included in the lens group closest to the object in the front group is f
• variable magnification optical system which satisfies conditional expression (28) represented by: [Additional Item 31]
• the focal length of the front lens group when focused on an object at infinity at the wide-angle end is fFw
• fMw is: 0.6 ⁇ fFw/(-fMw) ⁇ 5
• the distance on the optical axis between the lens group closest to the object side in the front group and the lens group closest to the image side in the intermediate group is dFMw;
• the focal length of the first subsequent lens group is fRA1, If the focal length of the third subsequent lens group is fRA3, 0.5 ⁇ fRA1/fRA3 ⁇ 4 (33)
• the variable magnification optical system according to claim 35 which satisfies conditional expression (33) represented by: [Additional Item 37]
• the focal length of the second subsequent lens group is fRA2, If the focal length of the fourth subsequent lens group is fRA4, 0.5 ⁇ fRA2/fRA4 ⁇ 8 (34)
• the focal length of the fourth subsequent lens group is fRA4, If the focal length of the fifth subsequent lens group is fRA5, 0.05 ⁇ fRA4/fRA5 ⁇ 3 (35) 38.
• variable magnification optical system according to any one of supplementary items 35 to 37, which satisfies conditional expression (35) represented by: [Additional Item 39]
• the focal length of the first subsequent lens group is fRB1, If the focal length of the second subsequent lens group is fRB2, 0.1 ⁇ fRB1/fRB2 ⁇ 9 (36) 40.
• the focal length of the first subsequent lens group is fRB1, If the focal length of the fourth subsequent lens group is fRB4, 0.2 ⁇ fRB1/fRB4 ⁇ 9 (37)
• the variable magnification optical system according to claim 39 or 40 which satisfies conditional expression (37) represented by: [Additional Item 42]
• the focal length of the third subsequent lens group is fRB3, If the focal length of the fifth subsequent lens group is fRB5, 0.1 ⁇ fRB3/fRB5 ⁇ 3 (38)
• the focal length of the first subsequent lens group is fRC1, If the focal length of the second subsequent lens group is fRC2, 0.1 ⁇ fRC1/fRC2 ⁇ 2 (39) 44.
• the variable magnification optical system according to claim 43 which satisfies conditional expression (39) represented by: [Additional Item 45]
• the focal length of the first subsequent lens group is fRD1, If the focal length of the second subsequent lens group is fRD2, 0.2 ⁇ fRD1/fRD2 ⁇ 3.5 (40) 46.
• a variable magnification optical system according to claim 45 which satisfies conditional expression (40) represented by: [Additional Item 47]
• the focal length of the third subsequent lens group is fRD3, If the focal length of the fourth subsequent lens group is fRD4, 0.05 ⁇ fRD3/fRD4 ⁇ 2 (41) 47.
• variable magnification optical system which satisfies conditional expression (41) represented by: [Additional Item 48]
• the focal length of the first subsequent lens group is fRE1, If the focal length of the third subsequent lens group is fRE3, 0.1 ⁇ fRE1/fRE3 ⁇ 3.5 (42) 49.
• the variable magnification optical system according to claim 48 which satisfies conditional expression (42) represented by: [Additional Item 50]
• the focal length of the third subsequent lens group is fRE3, If the focal length of the fifth subsequent lens group is fRE5, 0.1 ⁇ fRE3/fRE5 ⁇ 3.5 (43) 50.
• the focal length of the second subsequent lens group is fRE2.
• variable magnification optical system according to any one of supplementary items 48 to 50, which satisfies conditional expression (44) represented by: [Additional Item 52]
• the focal length of the fourth subsequent lens group is fRE4.
• variable magnification optical system according to any one of supplementary items 48 to 51, which satisfies conditional expression (45) represented by: [Additional Item 53]
• the focal length of the first subsequent lens group is fRF1
• the focal length of the third subsequent lens group is fRF3, 0.1 ⁇ fRF1/fRF3 ⁇ 2 (46) 54.
• the variable magnification optical system according to claim 53 which satisfies conditional expression (46) represented by: [Additional Item 55]
• the focal length of the second subsequent lens group is fRF2.
• the focal length of the fourth subsequent lens group is fRF4, 0.1 ⁇ fRF2/fRF4 ⁇ 2.5 (47) 55.
• variable magnification optical system according to claim 53 or 54, which satisfies conditional expression (47) represented by: [Additional Item 56]
• conditional expression (47) represented by: [Additional Item 56]
• the focal length of the first subsequent lens group is fRG1, If the focal length of the second subsequent lens group is fRG2, 0.01 ⁇ fRG1/fRG2 ⁇ 1 (48) 57.
• the variable magnification optical system according to claim 56 which satisfies conditional expression (48) represented by: [Additional Item 58]
• the focal length of the third subsequent lens group is fRG3, If the focal length of the second subsequent lens group is fRG2, 0.01 ⁇ fRG3/fRG2 ⁇ 1 (49) 58.
• the focal length of the fourth subsequent lens group is fRG4.
• a variable magnification optical system according to any one of supplementary items 56 to 58, which satisfies conditional expression (50) represented by: [Additional Item 60]
• the focal length of the first subsequent lens group is fRH1
• If the focal length of the second subsequent lens group is fRH2, 0.1 ⁇ fRH1/fRH2 ⁇ 2.5
• the variable magnification optical system according to claim 60 which satisfies conditional expression (51) represented by: [Additional Item 62]
• the focal length of the second subsequent lens group is fRH2, When the focal length of the fourth subsequent lens group is fRH4, 0.1 ⁇ fRH2/fRH4 ⁇ 2 (52) 62.
• variable magnification optical system which satisfies conditional expression (52) represented by: [Additional Item 63]
• the variable magnification optical system according to any one of Supplementary Items 1 to 34, wherein the rear group is composed of, in order from the object side to the image side, a first rear lens group having positive refractive power, a second rear lens group having negative refractive power, and a third rear lens group having positive refractive power.
• the focal length of the first subsequent lens group is fRI1
• If the focal length of the third subsequent lens group is fRI3, 0.1 ⁇ fRI1/fRI3 ⁇ 2
• the variable magnification optical system according to claim 63 which satisfies conditional expression (53) represented by: [Additional Item 65] 65.
• An imaging apparatus comprising the variable magnification optical system according to any one of claims 1 to 64.

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• 2024
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