Optical system and imaging device having the same

Abstract

To provide an optical system which is compact as a whole and yet allows an in-focus object surface to be significantly tilted while reducing composition shift.SOLUTION: A tilt-shooting compatible optical system is provided, comprising an object-side lens group, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, arranged in order from an object side. The first and third lens groups move in a direction having a component perpendicular to an optical axis for tilt shooting, and the object-side and second lens groups are stationary in the direction having the component perpendicular to the optical axis for tilt shooting.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical system and an imaging device having the same, and is particularly suitable for imaging devices using an image sensor, such as video cameras, electronic still cameras, broadcast cameras, and surveillance cameras. [Background technology]

[0002] Tilt photography is a technique that focuses on an object surface tilted relative to the optical axis. In tilt photography, it is necessary to tilt the object surface to a greater degree to broaden the range of visual expression.

[0003] An imaging optical system equipped with a tilt mechanism (or directional tilt mechanism) is known as an optical system that can achieve this type of imaging.

[0004] On the other hand, imaging optical systems with a tilt mechanism sometimes suffer from a shift in composition (hereinafter also referred to as "composition shift") when tilted, which can impair usability.

[0005] In contrast, an imaging optical system is known that has multiple lens units that move perpendicular to the optical axis (Patent Document 1). In Patent Document 1, during tilt photography, lens unit A moves perpendicular to the optical axis, and lens unit B moves perpendicular to the optical axis to correct the shift effect generated by lens unit A, thereby enabling tilt photography with small composition shift. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2019-090952 [Overview of the project] [Problems that the invention aims to solve]

[0007] In an imaging optical system equipped with multiple lens units that move perpendicular to the optical axis, such as in Patent Document 1, aberrations due to optical eccentricity occur during tilt imaging because the lens units move perpendicular to the optical axis. The amount of this eccentric aberration increases as the tilt of the object surface being tilted increases. In Patent Document 1, since the lens group A that moves perpendicular to the optical axis has a negative refractive power, the height of the off-axis light incident on lens unit B from the optical axis increases, and the amount of eccentric aberration that occurs when lens unit B is eccentric increases. In addition, the diameter of lens unit B increases because the height of the off-axis light from the optical axis increases. Therefore, it becomes difficult to increase the amount of eccentricity of lens unit B, and as a result, it is difficult to tilt the object surface that is in focus significantly.

[0008] Therefore, the present invention aims to provide an optical system and an imaging device having the same, which are compact as a whole system, and which can significantly tilt the plane of the object in focus while reducing composition shift. [Means for solving the problem]

[0009] The optical system of the present invention is an optical system capable of tilt imaging, and the optical system comprises, arranged in order from the object side, an object-side lens group, a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power. It consists of an image-side lens group. , the first lens group and the third lens group and For tilt photography, the lens group on the object side and the second lens group move in a direction that includes a component perpendicular to the optical axis, and the object-side lens group and the second lens group move in a direction that includes a component perpendicular to the optical axis. and the aforementioned image-side lens group and It is characterized by being immobile in a direction that includes a component perpendicular to the optical axis, which is necessary for tilt imaging. [Effects of the Invention]

[0010] According to the present invention, an optical system can be obtained that is compact as a whole, while reducing composition shift and significantly tilting the plane of the object in focus. [Brief explanation of the drawing]

[0011] [Figure 1]Cross-sectional views of the optical system of Example 1 (A) during normal shooting and at infinity focus, and (B) during tilt shooting and at finite distance focus [Figure 2] Longitudinal aberration diagrams of the optical system of Example 1 (A) during normal shooting and at infinity focus, and (B) during normal shooting and at finite distance focus [Figure 3] Lateral aberration diagram of the optical system of Example 1 during tilt shooting and at finite distance focus [Figure 4] Cross-sectional views of the optical system of Example 2 (A) during normal shooting and at infinity focus, and (B) during tilt shooting and at finite distance focus [Figure 5] Longitudinal aberration diagrams of the optical system of Example 2 (A) during normal shooting and at infinity focus, and (B) during normal shooting and at finite distance focus [Figure 6] Lateral aberration diagram of the optical system of Example 2 during tilt shooting and at finite distance focus [Figure 7] Cross-sectional views of the optical system of Example 3 (A) during normal shooting and at infinity focus, and (B) during tilt shooting and at finite distance focus [Figure 8] Longitudinal aberration diagrams of the optical system of Example 3 (A) during normal shooting and at infinity focus, and (B) during normal shooting and at finite distance focus [Figure 9] Lateral aberration diagram of the optical system of Example 3 during tilt shooting and at finite distance focus [Figure 10] Cross-sectional views of the optical system of Example 4 (A) during normal shooting and at infinity focus, and (B) during tilt shooting and at finite distance focus [Figure 11] Longitudinal aberration diagrams of the optical system of Example 4 (A) during normal shooting and at infinity focus, and (B) during normal shooting and at finite distance focus [Figure 12] Lateral aberration diagram of the optical system of Example 4 during tilt shooting and at finite distance focus [[ID=Z34]] [Figure 13] Cross-sectional views of the optical system of Example 5 (A) during normal shooting and at infinity focus, and (B) during tilt shooting and at finite distance focus [Figure 14](A) Longitudinal aberration diagram of the optical system in Example 5 during normal shooting and at infinity focus, (B) Longitudinal aberration diagram of the optical system during normal shooting and at finite distance focus. [Figure 15] Transverse aberration diagram of the optical system in Example 5 during tilt imaging and finite-distance focusing. [Figure 16] Cross-sectional view of the optical system of Example 6 during (A) normal shooting and infinity focus, and (B) tilt shooting and finite distance focus. [Figure 17] (A) Longitudinal aberration diagram of the optical system of Example 6 during normal shooting and at infinity focus, (B) Longitudinal aberration diagram of the optical system during normal shooting and at finite distance focus. [Figure 18] Transverse aberration diagram of the optical system of Example 6 during tilt imaging and finite-distance focusing. [Figure 19] Cross-sectional view of the optical system of Example 7 during (A) normal shooting and infinity focus, and (B) tilt shooting and finite distance focus. [Figure 20] (A) Longitudinal aberration diagram of the optical system of Example 7 during normal shooting and at infinity focus, (B) Longitudinal aberration diagram during normal shooting and at finite distance focus. [Figure 21] Transverse aberration diagram of the optical system in Example 7 during tilt imaging and finite-distance focusing. [Figure 22] Cross-sectional view of the optical system of Example 8 during (A) normal shooting and infinity focus, and (B) tilt shooting and finite distance focus. [Figure 23] (A) Longitudinal aberration diagram of the optical system of Example 8 during normal shooting and at infinity focus, (B) Longitudinal aberration diagram during normal shooting and at finite distance focus. [Figure 24] Transverse aberration diagram of the optical system in Example 8 during tilt imaging and finite-distance focusing. [Figure 25] Schematic diagram of the main components of the imaging device of the present invention. [Figure 26] Diagram illustrating the principle of Scheinproof [Figure 27] A diagram illustrating how image distortion is corrected by the parallel eccentricity of the lens group. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0013] In each lens cross-sectional view, the left side is the object side (front), and the right side is the image side (rear). The optical system of each embodiment is composed of multiple lens groups.

[0014] In this specification, a lens group refers to a collection of lenses that are eccentric with respect to the optical axis during tilt photography, or a collection of fixed lenses. A lens group may consist of one lens or multiple lenses. A lens group may also include an aperture diaphragm.

[0015] Figures 1, 4, 7, 10, 13, 16, 19, and 22 (A) are cross-sectional views of the optical systems of Examples 1 to 8 during normal shooting and at infinite focus, respectively, and (B) are cross-sectional views of the optical systems of Examples 1 to 8 during tilt shooting when focused at a finite distance.

[0016] The IP is the image plane, and when the optical system of each embodiment is used as the shooting optical system of a digital still camera or digital video camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed on it. When the optical system of each embodiment is used as the shooting optical system of a silver halide film camera, a photosensitive surface corresponding to the film surface is placed on the image plane IP.

[0017] Figures 2, 5, 8, 11, 14, 17, 20, and 23 (A) are longitudinal aberration diagrams of the optical systems of Examples 1 to 8 during normal shooting and at infinity focus, respectively. Figures (B) are longitudinal aberration diagrams of the optical systems of Examples 1 to 8 during tilt shooting focused at a finite distance, respectively. Here, "normal shooting" refers to the state in which the lens group is not eccentric.

[0018] In the spherical aberration diagram, the solid line represents the d line (wavelength 587.6 nm), and the dashed line represents the g line (wavelength 435.8 nm). In the astigmatism diagram, the dashed line M represents the meridional image plane, and the solid line S represents the sagittal image plane. The distortion diagram shows the amount of distortion relative to the d line. Lateral chromatic aberration is represented by the g line. ω is the half-angle of view (degrees), and Fno is the F number.

[0019] Figure 3(A) is a lateral aberration diagram of tilt imaging in Example 1, where the object surface located approximately 9000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 3(B) is a lateral aberration diagram of tilt imaging in Example 1, where the object surface located approximately 212 mm away from the first surface along the optical axis is tilted at approximately 25 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 6(A) is a lateral aberration diagram of tilt imaging in Example 2, where the object surface located approximately 9000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 6(B) is a lateral aberration diagram of tilt imaging in Example 2, where the object surface located approximately 212 mm away from the first surface along the optical axis is tilted at approximately 25 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system.

[0020] Figure 9(A) is a lateral aberration diagram of tilt imaging in Example 3, where the object surface located approximately 9000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 9(B) is a lateral aberration diagram of tilt imaging in Example 3, where the object surface located approximately 595 mm away from the first surface along the optical axis is tilted at approximately 25 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 12(A) is a lateral aberration diagram of tilt imaging in Example 4, where the object surface located approximately 5000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 12(B) is a lateral aberration diagram of tilt imaging in Example 4, where the object surface located approximately 109 mm away from the first surface along the optical axis is tilted at approximately 12 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system.

[0021] Figure 15(A) is a lateral aberration diagram of tilt imaging in Example 5, where the object surface located approximately 5000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 15(B) is a lateral aberration diagram of tilt imaging in Example 5, where the object surface located approximately 75 mm away from the first surface along the optical axis is tilted at approximately 12 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 18(A) is a lateral aberration diagram of tilt imaging in Example 6, where the object surface located approximately 9000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 18(B) is a lateral aberration diagram of tilt imaging in Example 6, where the object surface located approximately 185 mm away from the first surface along the optical axis is tilted at approximately 20 degrees in the direction of the optical axis of the imaging optical system.

[0022] Figure 21(A) is a lateral aberration diagram of tilt imaging in Example 7, where the object plane located approximately 7500 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 21(B) is a lateral aberration diagram of tilt imaging in Example 7, where the object plane located approximately 432 mm away from the first surface along the optical axis is tilted at approximately 15 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 24(A) is a lateral aberration diagram of tilt imaging in Example 8, where the object plane located approximately 9000 mm away from the first surface along the optical axis is tilted at approximately 82 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system. Figure 24(B) is a lateral aberration diagram of tilt imaging in Example 8, where the object plane located approximately 212 mm away from the first surface along the optical axis is tilted at approximately 25 degrees with respect to the direction perpendicular to the optical axis of the imaging optical system.

[0023] In the lateral aberration diagram, the dashed line M represents the meridional image plane, and the solid line S represents the sagittal image plane.

[0024] Furthermore, focusing on an object surface that is tilted relative to the direction perpendicular to the optical axis is called tilt photography.

[0025] Next, the principle of tilt imaging in the optical system of this embodiment will be explained.

[0026] Figure 26 illustrates the principle of Scheinproof. A lens with a principal plane perpendicular to the optical axis causes an object plane tilted at an angle θobj in the direction of the optical axis of the imaging optical system to have a conjugate relationship with the image plane tilted at an angle θimg from the vertical plane. Since the image plane of a typical imaging device is perpendicular to the optical axis, an object plane tilted beyond the depth of field cannot be brought into good focus.

[0027] As a method for correcting the image plane tilt (hereinafter referred to as image distortion) θimg caused by the tilt θobj of the object plane, lens eccentricity is used. By eccentricating the lens, the image plane tilts in the direction of the optical axis, and good focus can be obtained for the tilted object plane by the Scheinproof principle (Figure 27). However, as the object plane tilted by angle θobj approaches the principal plane of the lens, that is, as close-up photography occurs, the amount of image distortion due to the tilt of the object plane increases. Therefore, in order to focus on the image plane perpendicular to the optical axis, the amount of lens eccentricity needs to be increased.

[0028] Therefore, in the optical system of this embodiment, in order to make the entire system compact and to tilt the object plane in focus significantly from objects at infinity to objects at close range, a first lens group and a third lens group are arranged that have a component that moves perpendicular to the optical axis. Furthermore, a second lens group is placed between the first and third lens groups, which is stationary in a direction that includes a component perpendicular to the optical axis for tilt photography. By moving a part of the optical system, it becomes easy to tilt the object plane in focus significantly while reducing composition shift, even though the entire system is compact.

[0029] Next, we will describe the characteristic configurations of the optical systems in each embodiment.

[0030] The optical system of each embodiment is capable of tilt imaging and has, arranged in order from the object side, an object-side lens group LF, a first lens group La with positive refractive power, a second lens group Lb with positive refractive power, and a third lens group Lc with negative refractive power. The first lens group La and the third lens group Lc move in a direction that includes a component perpendicular to the optical axis during tilt imaging, while the second lens group Lb remains stationary in a direction that includes a component perpendicular to the optical axis for tilt imaging.

[0031] By moving the first lens group La and the third lens group Lc during tilt photography, the system is more compact than configurations that tilt the entire optical system. Furthermore, compared to configurations using only one lens group for tilt photography, it allows for correction of compositional shift, making tilt photography with minimal compositional changes easier. Additionally, moving two lens groups facilitates correction of various aberrations such as coma and chromatic aberration caused by eccentricity.

[0032] Furthermore, a second lens group Lb is positioned between the first lens group La and the third lens group Lc, and is fixed in a direction that includes a component perpendicular to the optical axis for tilt imaging. This allows the control of the light rays incident on the third lens group Lc to be performed by multiple lens groups, enabling good correction of various aberrations such as coma aberration and chromatic aberration due to eccentricity. In addition, by keeping the second lens group Lb fixed during tilt imaging, the mechanical mechanism during eccentricity is simplified, manufacturing variations are suppressed, and performance can be improved.

[0033] Furthermore, the object-side lens group LF is fixed in a direction that includes a component perpendicular to the optical axis for tilt imaging. Lens groups placed on the object side tend to increase in size in the radial direction, and adding a mechanical mechanism for eccentricity would further increase the size, so fixing them during tilt imaging suppresses the increase in size.

[0034] Furthermore, the first lens group La has positive refractive power, the second lens group Lb has positive refractive power, and the third lens group Lc has negative refractive power. The positive refractive power of the first lens group La and the second lens group Lb reduces the height of the off-axis rays incident on the third lens group Lc from the optical axis, thereby miniaturizing the third lens group Lc. In addition, suppressing the height of the off-axis rays incident on the third lens group suppresses various aberrations that occur when the third lens group Lc is eccentric.

[0035] Furthermore, the third lens group Lc has negative refractive power, which shifts the front principal point of the entire L0 system toward the object, thereby miniaturizing the entire L0 system.

[0036] Furthermore, it is preferable that the optical system of each embodiment satisfies one or more of the following conditions. Ma max / Mc max >0···(1) 0.05 <fa / f<2.00···(2) -2.00 <fc / f<-0.05···(3) 0.4 <|Pa|+|Pc|<12.0···(4) 0 <Lbk / f<0.65···(5) 0.5 <f / fb<10.0···(6) β < -0.25 ···(7) 0.01<|Ma max / fa|<0.30···(8) 0.01<|Mc max / fc|<0.30···(9) -0.8<(Rfa+Rra) / (Rra-Rfa)<0.8...(10) -0.8<(Rfc+Rrc) / (Rrc-Rfc)<0.8...(11) -3.00 <mLf2 / mLf1<-0.10···(12)

[0037] The maximum movement of the first lens group La in the direction perpendicular to the optical axis is Ma max Mc maxHere, the maximum displacement is defined as the radial difference between the vertex of the surface and the optical axis when the lens group moves for tilt shooting, compared to the state without tilt shooting. The direction in which the first lens group La moves is considered positive, and the direction opposite to the direction in which the first lens group La moves is considered negative. If the displacement differs for each vertex of the surface, the largest displacement among the comparisons for each vertex of the surface is defined as the maximum displacement.

[0038] Let the focal length of the first lens group La be fa, and the focal length of the third lens group Lc be fc. Let the Petzval sum of the first lens group La be Pa, and the Petzval sum of the third lens group Lc be Pc. Let the focal length of the entire optical system L0 be f, and the back focus of the optical system L0 be Lbk. Let the focal length of the second lens group Lb be fb. Let the lateral magnification of the optical system L0 at its closest focus be β. Let the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object in the first lens group be Rfa, and the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image in the first lens group La be Rra.

[0039] Let Rfc be the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object in the third lens group, and let Rrc be the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image in the third lens group Lc. Let mLf1 be the amount of focusing movement of the first focus group Lf1 in the object-side lens group LF from infinity to the closest distance. Let mLf2 be the amount of focusing movement of the second focus group Lf2, which is positioned closer to the image than the first focus group Lf1, from infinity to the closest distance. Here, the amount of focusing movement is considered positive when moving from the image side to the object side, and negative when moving from the object side to the image side.

[0040] Next, we will explain the technical meaning of each of the aforementioned conditional expressions.

[0041] Condition (1) represents the ratio of the amount of movement of the first lens group La in the direction perpendicular to the optical axis due to eccentricity to the amount of movement of the third lens group Lc in the direction perpendicular to the optical axis due to eccentricity. When condition (1) is satisfied, the directions of composition shift due to each eccentricity are opposite, thus canceling out the composition shift. In other words, the composition shift is suppressed. If the directions of movement are opposite, the composition shift is amplified, which is undesirable.

[0042] Conditional equation (2) specifies the ratio of the focal length of the first lens group La to the total focal length of the optical system L0. If it falls below the lower limit, the amount of eccentricity aberration per unit eccentricity increases, making it difficult to maintain good optical performance during tilt photography. If it exceeds the upper limit, a large amount of eccentricity is required to tilt the object plane in focus significantly, which leads to an increase in the lens diameter of the first lens group, resulting in a larger size.

[0043] Conditional equation (3) specifies the ratio of the focal length of the third lens group Lc to the total focal length of the optical system L0. If it falls below the lower limit, a large amount of eccentricity is required to tilt the object plane in focus significantly, which leads to an increase in the lens diameter of the third lens group Lc, resulting in a larger size. If it exceeds the upper limit, the amount of eccentric aberration per unit eccentricity increases, making it difficult to maintain good optical performance during tilt photography, which is undesirable.

[0044] Conditional equation (4) specifies the sum of the Petzval sum of the first lens group La and the Petzval sum of the third lens group. If it falls below the lower limit, a large amount of eccentricity is required to tilt the object plane in focus significantly during tilt photography, which leads to an increase in the lens diameter of the eccentric lens group, resulting in a larger optical system. If it exceeds the upper limit, the amount of eccentric aberration per unit eccentricity increases, making it difficult to maintain good optical performance during tilt photography.

[0045] The Petzval sum of condition (4) is defined by the following formula.

[0046]

number

[0047] Pν: Petzval sum of the ν-face rν: radius of paraxial curvature of the ν-th surface Nν: Refractive index of the d-line in the incident medium of the ν-plane. N′ν: Refractive index of the d-line in the ejection-side medium of the ν-plane. f: focal length of the entire optical system

[0048] Conditional equation (5) specifies the ratio of the back focus to the focal length of the entire optical system L0. If it exceeds the upper limit, the overall length of the lens becomes long, which is undesirable. If it falls below the lower limit, it comes into contact with the image sensor, which is also undesirable. By positioning the lens at a height from the optical axis of the off-axis rays so as to satisfy conditional equation (5), the correction of field curvature becomes easier, and good optical performance can be achieved.

[0049] Conditional equation (6) specifies the ratio of the focal length of the entire optical system L0 to the focal length of the second lens group Lb. If it falls below the lower limit, the refractive power of the second lens group becomes too weak, making it difficult to suppress the height of off-axis rays incident on the third lens group, and the third lens group becomes larger, which is undesirable. If it exceeds the upper limit, the refractive power of the second lens group Lb becomes too strong, making it difficult to correct the various aberrations that occur in the second lens group.

[0050] Conditional equation (7) is a conditional equation relating to the magnification of the optical system L0. If the upper limit of this conditional equation is exceeded, a sufficient magnification cannot be obtained, making close-up photography difficult, which is undesirable.

[0051] Conditional equation (8) specifies the ratio of the focal length of the first lens group La to the maximum amount of vertical displacement of the first lens group with respect to the optical axis. If it falls below the lower limit, the amount of displacement of the first lens group with respect to the optical axis becomes small, making it difficult to tilt the object plane in focus significantly. If it exceeds the upper limit, the refractive power of the first lens group La becomes strong, increasing the amount of eccentric aberration per unit eccentricity, making it difficult to maintain good optical performance during tilt photography.

[0052] Conditional equation (9) specifies the ratio of the focal length of the third lens group Lc to the maximum vertical displacement of the third lens group Lc with respect to the optical axis. If it falls below the lower limit, the displacement of the third lens group Lc with respect to the optical axis becomes small, making it difficult to obtain sufficient image distortion during tilt photography, and thus difficult to significantly tilt the object plane in focus. If it exceeds the upper limit, the refractive power of the third lens group Lc becomes strong, increasing the amount of eccentric aberration per unit eccentricity, making it difficult to maintain good optical performance during tilt photography.

[0053] Conditional equation (10) defines the shape factors of the object-side lens surface of the lens positioned closest to the object in the first lens group La, and the image-side lens surface of the lens positioned closest to the image in the first lens group La. When the first lens group La approaches a meniscus shape, exceeding the upper limit or falling below the lower limit, the refractive power of the first lens group La decreases, and the amount of image distortion decreases, making it difficult to significantly tilt the object plane at focus.

[0054] Conditional equation (11) defines the shape factors of the object-side lens surface of the lens positioned closest to the object in the third lens group Lc, and the image-side lens surface of the lens positioned closest to the image in the third lens group Lc. When the third lens group Lc approaches a meniscus shape, exceeding the upper limit or falling below the lower limit, the refractive power of the third lens group Lc decreases, and the amount of image distortion decreases, making it difficult to significantly tilt the object plane at focus.

[0055] Conditional equation (12) defines the ratio of the amount of movement of the first focus group Lf1 during focusing to the amount of movement of the second focus group Lf2, which is positioned closer to the image than the first focus group Lf1. By having the first focus group Lf1 and the second focus group Lf2 move in opposite directions from infinity to the closest distance, it is easier to suppress variations in various aberrations associated with changes in object distance. If the value exceeds the upper limit, the amount of movement of the second focus group Lf2 becomes small, making it particularly difficult to correct field curvature aberration. If the value falls below the lower limit, the amount of movement of the first focus group Lf1 becomes small, making it particularly difficult to correct spherical aberration.

[0056] Preferably, in the optical system of each embodiment, the conditional expressions (1) to (12) are preferably set as follows. 0.30 < Ma max / Mc max < 3.00 ··· (1a) 0.10 < fa / f < 1.50 ··· (2a) -1.50 < fc / f < -0.10 ··· (3a) 0.8 < |Pa| + |Pc| < 10.0 ··· (4a) 0.05 < Lbk / f < 0.50 ··· (5a) 1.0 < f / fb < 9.0 ··· (6a) -2.5 < β < -0.3 ····· (7a) 0.02 < |Ma max / fa| < 0.25 ··· (8a) 0.02 < |M c max / fc| < 0.27 ··· (9a) -0.7 < (Rfa + Rra) / (Rra - Rfa) < 0.7 ··· (10a) -0.75 < (Rfb + Rrb) / (Rrb - Rfb) < 0.75 ··· (11a) -2.50 < mLf2 / mLf1 < -0.20 ··· (12a)

[0057] More preferably, in the optical system of each embodiment, the numerical ranges of the conditional expressions (1a) to (12a) are preferably set as follows. 0.60 < Ma max / Mc max < 2.50 ··· (1b) 0.15 < fa / f < 1.20 ··· (2b) -1.20 < fc / f < -0.15 ··· (3b) 1.2 < |Pa| + |Pc| < 8.0 ··· (4b) 0.07 < Lbk / f < 0.40 ··· (5b) 1.5 < f / fb < 8.0 ··· (6b) -1.5 < β < -0.32 ··· (7b) 0.03 < |Ma max / fa|<0.20···(8b) 0.05<|M c max / f c |<0.25···(9b) -0.6<(Rfa+Rra) / (Rra-Rfa)<0.6 (10b) -0.7<(Rfb+Rrb) / (Rrb-Rfb)<0.7 (11b) -2.00 <mLf2 / mLf1<-0.25···(12b)

[0058] Furthermore, it is preferable that the object-side lens group LF has a positive refractive power. Having a positive refractive power in the object-side lens group LF causes the axial light beam to converge, and the diameter of the lens group that moves during eccentricity can be reduced.

[0059] Furthermore, it is preferable that the object-side lens group LF has a focus group Lf1 that moves in the optical axis direction for focusing. By positioning the focus group at a location with a relatively large on-axial light flux, the amount of movement of the image plane in the optical axis direction relative to the amount of movement per unit when the focus group Lf1 moves for focusing can be increased. Therefore, the amount of movement of the focus group Lf1 from infinity to the closest distance can be reduced, eliminating the need for extra space and allowing the entire system to be miniaturized.

[0060] Furthermore, it is preferable to have a focus group Lf2 that moves closer to the image than the focus group Lf1 for focusing. By moving multiple focus groups for focusing, it is possible to more easily correct aberrations caused by changes in object distance and improve close-up performance.

[0061] In each embodiment, by identifying each element as described above, an optical system is obtained that is compact overall while reducing composition shift and significantly tilting the plane of the object in focus.

[0062] Next, the lens configuration of each embodiment will be described in detail.

[0063] The optical system L0 of Example 1 is composed of the following lens groups arranged in order from the object side: object-side lens group LF, focus group Lf1, focus group Lf2, first lens group La, second lens group Lb, third lens group Lc, and image-side lens group LR. The image-side lens group LR is positioned closer to the image than the third lens group Lc. This allows the image-side lens group LR to be positioned at a high position for off-axis rays, effectively correcting field curvature. Furthermore, focus groups Lf1 and Lf2 are positioned close to the aperture. This positions focus groups Lf1 and Lf2 at a low position for off-axis rays, reducing the diameters of focus groups Lf1 and Lf2.

[0064] The optical system L0 of Example 2 has a configuration of two lenses each for the first lens group La and the third lens group Lc, consisting of a positive lens and a negative lens. This makes it possible to further suppress the occurrence of chromatic aberration even when the first lens group La and the third lens group Lc become eccentric during tilt photography.

[0065] In the optical system L0 of Example 3, the only group that moves for focusing is the focus group Lf1. By having only one moving group, variations during manufacturing are suppressed, resulting in improved performance. Furthermore, a negative lens that does not move for focusing and does not move for tilt photography is placed between the focus group Lf1 and the first lens group La. This facilitates the control of light rays incident on the first lens group La from the object side, resulting in improved performance for tilt photography.

[0066] In the optical system L0 of Example 4, the focusing group Lf2 is positioned within the image-side lens group LR. This positions the focusing group Lf2 at a high position for off-axis rays, effectively correcting off-axis aberrations such as field curvature that occur when the object distance changes.

[0067] The optical system L0 of Example 5 has a cemented lens consisting of a positive lens and a negative lens in the focusing group Lf1 and the focusing group Lf2, respectively. This suppresses the variation in chromatic aberration that occurs when focusing from infinity to the closest distance.

[0068] The optical system L0 of Example 6 has a cemented negative lens and a positive lens positioned between the focus group Lf1 and the first lens group La, which do not move for focusing and also do not move for tilt photography. This suppresses chromatic aberration related to the eccentricity that occurs during tilt photography, thereby improving performance for tilt photography.

[0069] In the optical system L0 of Example 7, the only group that moves for focusing is the focusing group Lf1, which is located within the image-side lens group LR. By placing it within the image-side lens group LR, the on-axial light beam is relatively small, which reduces the diameter of the focusing group Lf1.

[0070] The optical system L0 of Example 8 consists of two positive lenses in the second lens group Lb. By sharing the refractive power, off-axis rays are gently bent, suppressing the occurrence of aberrations related to eccentricity and improving performance for tilt imaging.

[0071] Furthermore, in Examples 1 to 8, it is preferable that all the lenses used are spherical lenses in order to suppress the degradation of optical performance due to manufacturing errors.

[0072] Next, an example of a digital still camera (imaging device) using the optical system of this embodiment as the imaging optical system will be described with reference to Figure 25. In Figure 25, 13 is the camera body, and 11 is the imaging optical system composed of any of the optical systems described in Examples 1 to 8. 12 is a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor, which is built into the camera body and receives the optical image formed by the imaging optical system 11 and converts it into photoelectric light. The camera body 13 may be a so-called single-lens reflex camera with a quick-turn mirror, or a so-called mirrorless camera without a quick-turn mirror.

[0073] By applying the optical system of this embodiment to an imaging device such as a digital still camera, it is possible to obtain an imaging device that has a small lens, suppresses composition shift, and can tilt the plane of the object in focus significantly.

[0074] The following shows specific numerical examples corresponding to Examples 1 through 8.

[0075] In the surface data for each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axial spacing (distance along the optical axis) between the m-th surface and the (m+1)-th surface. Here, m is the surface number counted from the light incidence side. Furthermore, nd represents the refractive index of each optical element with respect to the d-line, and νd represents the Abbe number of the optical element. Note that the Abbe number νd of a certain material is given by Nd, NF, and NC, respectively, when the refractive indices at the Fraunhofer lines d-line (587.6 nm), F-line (486.1 nm), and C-line (656.3 nm) are Nd, NF, and NC, respectively. It is expressed as νd = (Nd-1) / (NF-NC).

[0076] Furthermore, in each numerical example, d, focal length (mm), F-number, and half-angle of view (°) are all values ​​when the optical system of each example is focused at infinity. "Back focus BF" is the distance along the optical axis from the final lens surface (the lens surface closest to the image) to the paraxial image plane, expressed in terms of air equivalent length. "Total lens length" is the length obtained by adding the back focus to the distance along the optical axis from the frontmost lens surface (the lens surface closest to the object) to the final surface of the zoom lens. "Lens group" includes not only cases where it is composed of multiple lenses, but also cases where it is composed of a single lens.

[0077] [Numerical Example 1] Unit: mm Surface data Face number rd nd νd 1 174.719 4.93 1.48749 70.2 2 -267.020 2.00 3 80.513 4.62 1.49684 81.7 4 285.557 5.29 5 50.471 7.23 1.49629 82.0 6 -511.388 1.93 1.70967 56.3 7 41.048 (variable) 8 41.700 4.87 1.49619 82.0 9 -6326.860 0.20 10 68.544 1.42 1.77124 50.5 11 27.709 5.20 1.49599 82.1 12 -888.343 (variable) 13 (aperture) ∞ (variable) 14 -119.115 1.72 1.81505 46.8 15 44.102 2.36 16 -85.452 1.75 1.81509 46.8 17 54.420 3.23 1.90264 19.5 18 -416.345 (variable) 19 112.731 1.87 1.92330 18.9 20 54.385 1.96 21* 61.745 6.27 1.58313 59.4 22* -38.905 1.91 23* 47.660 8.20 1.49700 81.5 24* -37.336 1.72 25* -139.574 1.88 1.58313 59.4 26* 29.777 6.85 27 -88.136 4.55 1.72165 44.2 28 -28.483 1.98 1.49652 82.0 29 81.833 16.86 30 -67.083 1.99 1.59885 67.4 31 271.152 0.18 32 37.993 5.43 1.49939 76.3 33 112.075 (variable) Image plane ∞ Aspherical data Page 21 K = 0.00000e+00 A 4=-3.48002e-06 A 6=-6.56240e-09 A 8= 4.08341e-11 A10=-5.55830e-14 Page 22 K = 0.00000e+00 A 4= 6.17521e-06 A 6=-4.89932e-09 A 8= 1.54432e-11 A10=-9.57953e-15 Page 23 K = 0.00000e+00 A 4= 2.09252e-06 A 6=-6.35516e-10 A 8= 1.32715e-12 A10= 2.01394e-15 Page 24 K = 0.00000e+00 A 4= 5.96878e-06 A 6=-2.65107e-09 A 8= 7.36761e-12 A10=-3.82552e-15 Page 25 K = 0.00000e+00 A 4= 1.96060e-05 A 6=-7.08573e-08 A 8= 1.51309e-10 A10=-1.46756e-13 Page 26 K = 0.00000e+00 A 4= 1.78945e-05 A 6=-5.37049e-08 A 8= 7.12464e-11 A10= 7.47341e-15 Various data Focal length 179.88 F-number 3.60 Field of view 6.86 Image height 21.64 Lens length: 198.10 BF 27.03

[0078] Figure 3(A) shows the aberration diagram for tilt imaging 1 in numerical example 1, and Figure 3(B) shows the aberration diagram for tilt imaging 2.

[0079] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d 7 45.15 21.15 44.65 21.63 d12 2.82 26.82 3.31 26.33 d13 3.31 12.80 3.60 12.80 d18 11.40 1.91 11.10 1.90 d20 1.96 1.96 1.96 1.96 d22 1.91 1.91 1.91 1.91 d24 1.72 1.72 1.72 1.72 d26 6.85 6.85 6.85 6.85 d33 27.03 27.03 26.90 26.90 Tilt shooting 1 Tilt shooting 2 Ma 1.82 5.55 Mb 2.46 7.52 Lens group data Group starting plane focal length 1 1 264.44 2 8 71.84 3 14 -31.91 4 19 -115.58 5 21 41.89 6 23 43.52 7 25 -41.91 8 27 -111.44

[0080] [Numerical Example 2] Unit: mm Surface data Face number rd nd νd 1 136.089 5.05 1.48749 70.2 2 -389.025 2.02 3 72.988 5.29 1.49700 81.5 4 389.581 2.03 5 47.577 7.39 1.49700 81.5 6 -1571.141 1.96 1.73623 54.0 7 37.966 (variable) 8 38.764 4.87 1.49700 81.5 9 -1245.436 0.20 10 73.334 1.32 1.74071 53.5 11 25.419 4.98 1.49700 81.5 12 2315.989 (variable) 13 (aperture) ∞ (variable) 14 -156.211 1.73 1.81530 46.8 15 38.210 2.46 16 -73.964 1.86 1.72885 54.8 17 54.561 3.14 1.89883 19.6 18 -443.151 (variable) 19 140.170 1.88 1.92318 18.9 20 70.989 1.93 21 78.105 1.85 1.84670 23.8 22 62.149 6.67 1.58313 59.4 23* -34.338 1.83 24* 38.026 8.60 1.49700 81.5 25* -36.702 1.74 26 -68.602 2.94 1.61671 37.3 27 -39.262 1.73 1.58313 59.4 28* 22.820 7.29 29 -54.316 4.56 1.49681 81.8 30 66.821 2.72 31 41.836 9.40 1.65966 33.2 32 -31.910 6.30 1.91663 31.6 33 71.441 0.06 34 41.525 11.99 1.52629 50.6 35 813.184 (variable) Image plane ∞ Aspherical data Page 23 K = 0.00000e+00 A 4= 1.08438e-05 A 6=-1.38407e-08 A 8= 2.21357e-11 A10=-1.13390e-14 Page 24 K = 0.00000e+00 A 4= 3.50524e-06 A 6= 7.05381e-09 A 8=-3.59642e-11 A10= 7.00151e-14 Page 25 K = 0.00000e+00 A 4= 8.66648e-06 A 6= 1.16632e-09 A 8=-2.32100e-11 A10= 5.45548e-14 Page 28 K = 0.00000e+00 A 4=-1.60218e-05 A 6= 4.08680e-08 A 8=-1.19153e-10 A10= 1.38194e-13 Various data Focal length 179.86 F-number 3.60 Field of view 6.86 Image height 21.64 Lens length: 195.15 BF 17.69

[0081] Figure 6(A) shows the aberration diagram for tilt imaging 1 in numerical example 2, and Figure 6(B) shows the aberration diagram for tilt imaging 2.

[0082] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d 7 44.46 20.46 44.10 20.70 d12 2.88 26.88 3.24 26.64 d13 3.07 12.49 3.48 12.22 d18 11.26 1.84 10.84 2.11 d20 1.93 1.93 1.93 1.93 d23 1.83 1.83 1.83 1.83 d25 1.74 1.74 1.74 1.74 d28 7.29 7.29 7.29 7.29 d35 17.69 17.69 17.54 17.54 Tilt shooting 1 Tilt shooting 2 Ma 1.92 5.90 Mb 2.02 6.23 Lens group data Group starting plane focal length 1 1 232.95 2 8 73.16 3 14 -31.86 4 19 -157.86 5 21 43.54 6 24 39.07 7 26 -29.14 8 29 -106.26

[0083] [Numerical Example 3] Unit: mm Surface data Face number rd nd νd 1 248.262 3.70 1.48749 70.2 2 1040.268 0.16 3 89.135 9.61 1.49700 81.5 4 -466.470 0.16 5 76.591 10.21 1.49700 81.5 6 -256.118 5.43 1.77633 50.0 7 161.387 23.04 8 46.441 1.97 1.87912 39.4 9 29.971 7.12 1.49626 82.2 10 256.375 2.53 11 (aperture) ∞ (variable) 12 5386.597 1.77 1.84051 31.4 13 40.149 3.39 14 -179.195 1.77 1.85486 41.9 15 43.546 4.34 1.91994 19.0 16 3763.832 (variable) 17 169.526 7.19 1.92302 18.9 18 68.493 1.91 19 62.961 6.27 1.58313 59.4 20* -57.081 1.87 21* 40.089 5.73 1.49700 81.5 22* -65.762 1.72 23 -96.550 1.81 1.58313 59.4 24* 32.706 6.19 25 -53.257 1.99 1.49691 81.7 26 80.104 2.95 27 273.792 10.01 1.56045 44.6 28 -33.197 6.36 29 -31.476 2.00 1.49670 81.9 30 103.437 0.13 31 45.287 6.83 1.51332 56.3 32 -275.551 26.48 Image plane ∞ Aspherical data Page 20 K = 0.00000e+00 A 4= 3.65690e-06 A 6=-4.01390e-09 A 8= 3.99705e-12 A10=-3.36245e-16 Page 21 K = 0.00000e+00 A 4= 1.23010e-06 A 6= 1.30868e-08 A 8=-8.01089e-11 A10= 2.13661e-13 Page 22 K = 0.00000e+00 A 4= 6.54254e-07 A 6= 1.19822e-08 A 8=-6.86727e-11 A10= 1.78656e-13 Page 24 K = 0.00000e+00 A 4=-1.78967e-06 A 6= 1.24701e-08 A 8=-4.27471e-11 A10= 9.31861e-14 Various data Focal length 193.86 F-number 2.88 Field of view 6.37 Image height 21.64 Lens length: 182.73 BF 26.48

[0084] Figure 9(A) shows the aberration diagram for tilt imaging 1 in numerical example 3, and Figure 9(B) shows the aberration diagram for tilt imaging 2.

[0085] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d11 2.88 15.44 3.63 15.66 d16 15.23 2.66 14.47 2.44 d18 1.91 1.91 1.91 1.91 d20 1.87 1.87 1.87 1.87 d22 1.72 1.72 1.72 1.72 d24 6.19 6.19 6.19 6.19 d32 26.48 26.48 26.48 26.48 Tilt shooting 1 Tilt shooting 2 Ma 3.40 3.62 Mb 3.65 3.88 Zoom lens group data Group starting plane focal length 1 1 81.09 2 12 -40.77 3 17 -128.92 4 19 52.35 5 21 51.03 6 23 -41.68 7 25 -476.12

[0086] [Numerical Example 4] Unit: mm Surface data Face number rd nd νd 1 -87.304 1.89 1.90018 37.5 2 31.676 14.23 1.65589 33.4 3 -88.869 0.10 4 200.218 4.12 1.84891 24.0 5 -176.528 6.83 6 60.718 9.67 1.49674 81.7 7 -52.644 -0.03 8 -119.201 1.81 1.65882 33.2 9 37.467 3.04 10 102.722 1.78 1.84676 23.8 11 49.442 5.65 1.62499 64.4 12 -314.146 0.20 13 40.889 6.40 1.73134 54.5 14 -247.204 2.82 15 (aperture) ∞ (variable) 16 -108.719 0.79 1.90060 37.4 17 39.919 3.05 18 -533.007 1.22 1.91521 32.1 19 36.279 5.43 1.92286 18.9 20 -171.574 (variable) 21 89.651 1.69 1.92292 19.3 22 44.378 2.87 23* 103.849 4.96 1.58313 59.4 24* -65.886 1.49 25 124.749 5.76 1.73746 53.9 26 -51.253 9.98 27 -377.683 4.47 1.90053 37.4 28 51.355 7.26 1.60145 39.0 29 -33.786 1.61 30* -40.284 1.19 1.58313 59.4 31 * 33.956 (variable) 32 -26.018 7.46 1.81625 46.6 33 -53.874 -0.06 34 62.385 5.92 1.49670 81.9 35 -118.740 (variable) 36 735.319 1.83 1.70004 30.1 37 112.303 14.71 Image plane ∞ Aspherical data Page 23 K = 0.00000e+00 A 4= 1.42671e-06 A 6= 4.18018e-09 A 8= 1.15895e-12 A10= 5.19331e-15 Page 24 K = 0.00000e+00 A 4= 1.75596e-06 A 6= 4.29665e-09 A 8=-3.88295e-12 A10= 1.80763e-14 Page 30 K = 0.00000e+00 A 4=-8.56454e-06 A 6= 7.60633e-08 A 8=-3.68738e-10 A10= 5.42586e-13 Page 31 K = 0.00000e+00 A 4=-6.48869e-06 A 6= 7.22512e-08 A 8=-3.07607e-10 A10= 4.08475e-13 Various data Focal length 97.23 F-number 2.88 Field of view 12.54 Image height 21.64 Lens length: 176.52 BF 14.71

[0087] Figure 12(A) shows the aberration diagram for tilt imaging 1 of numerical example 4, and Figure 12(B) shows the aberration diagram for tilt imaging 2.

[0088] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d15 3.63 20.17 3.91 19.94 d20 18.25 1.70 17.97 1.94 d22 2.87 2.87 2.87 2.87 d24 1.49 1.49 1.49 1.49 d29 1.61 1.61 1.61 1.61 d31 7.79 12.78 8.47 10.78 d35 6.71 1.72 6.03 3.72 d37 14.71 14.71 14.71 14.71 Zoom lens group data Group starting plane focal length 1 1 40.42 2 16 -38.37 3 21 -96.96 4 23 69.88 5 25 38.64 6 30 -31.41 7 32 -2080.36 8 36 -189.57 Tilt shooting 1 Tilt shooting 2 Ma 2.22 3.37 Mb 2.12 3.18

[0089] [Numerical Example 5] Unit: mm Surface data Face number rd nd νd 1 -45.764 4.45 1.90061 37.4 2 48.352 7.05 1.84667 23.8 3 95.755 1.29 4 93.722 5.94 1.75815 51.7 5 -96.642 0.11 6 2265.562 4.85 1.49689 81.6 7 -49.411 0.08 8 119.258 1.90 1.56124 46.7 9 40.472 2.17 10 100.441 1.92 1.87539 26.5 11 43.591 5.96 1.62831 64.0 12 -140.854 0.20 13 44.123 4.85 1.81643 46.6 14 -5194.885 2.93 15 (aperture) ∞ (variable) 16 565.913 1.85 1.66816 59.8 17 32.802 4.08 18 -93.004 1.96 1.69895 30.1 19 42.701 7.00 1.92322 18.9 20 -128.791 (variable) 21 -81.578 4.45 1.85264 23.4 22 73.624 1.93 23* 75.367 5.31 1.58313 59.4 24* -65.208 5.31 25* 70.409 8.58 1.58313 59.4 26* -45.942 1.97 27* -43.449 1.91 1.58313 59.4 28 * 234.483 (variable) 29 126.223 4.06 1.58682 40.8 30 -133.290 0.12 31 67.398 6.53 1.49674 81.6 32 -59.104 1.62 1.77332 26.5 33 -297.679 (variable) 34 -93.896 3.89 1.84664 23.8 35 -42.064 1.95 1.79584 48.3 36 69.704 28.19 Image plane ∞ Aspherical data Page 23 K = 0.00000e+00 A 4= 1.11099e-06 A 6=-7.29024e-09 A 8= 4.55355e-11 A10=-4.80346e-14 Page 24 K = 0.00000e+00 A 4=-4.92123e-06 A 6=-3.26667e-09 A 8= 4.29777e-11 A10=-4.54461e-14 Page 25 K = 0.00000e+00 A 4= 9.62743e-07 A 6= 2.46457e-09 A 8=-1.40208e-11 A10= 3.68058e-14 Page 26 K = 0.00000e+00 A 4= 8.94948e-07 A 6= 2.56214e-09 A 8=-1.02963e-11 A10= 2.94297e-14 Page 27 K = 0.00000e+00 A 4=-1.09391e-07 A 6= 1.89244e-08 A 8=-2.42908e-11 A10=-3.62793e-14 Page 28 K = 0.00000e+00 A 4= 5.11595e-06 A 6= 1.68284e-08 A 8=-3.73237e-11 A10= 1.67514e-15 Various data Focal length 89.85 F-number 3.50 Field of view 13.54 Image height 21.64 Lens length: 184.06 BF 28.19

[0090] Figure 15(A) shows the aberration diagram for tilt imaging 1 in numerical example 5, and Figure 15(B) shows the aberration diagram for tilt imaging 2.

[0091] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d15 2.87 15.87 3.05 14.76 d20 16.88 3.88 16.69 4.98 d22 1.93 1.93 1.93 1.93 d24 5.31 5.31 5.31 5.31 d26 1.97 1.97 1.97 1.97 d28 26.95 1.95 26.44 3.67 d33 2.95 27.95 3.46 26.23 d36 28.19 28.19 28.19 28.19 Tilt shooting 1 Tilt shooting 2 Ma 2.43 4.02 Mb 2.94 4.40 Zoom lens group data Group starting plane focal length 1 1 41.51 2 16 -77.33 3 21 -44.80 4 23 60.80 5 25 49.01 6 27 -62.70 7 29 69.74 8 34 -51.24

[0092] [Numerical Example 6] Unit: mm Surface data Face number rd nd νd 1 137.765 5.14 1.48749 70.2 2 -281.582 0.13 3 91.383 4.03 1.85045 24.1 4 265.043 0.13 5 55.834 6.98 1.49590 82.3 6 -803.214 1.87 1.90057 37.4 7 45.295 (variable) 8 61.343 5.09 1.49626 81.9 9 -191.306 0.20 10 63.177 1.38 1.65679 33.4 11 35.567 4.89 1.49594 82.2 12 1015.441 (Variable) 13 (Aperture) ∞ 2.97 14 -441.273 1.82 1.87270 40.0 15 45.301 2.93 16 -86.856 1.92 1.55060 73.5 17 59.078 2.34 1.92307 18.9 18 91.530 2.76 19* 132.865 5.52 1.58313 59.4 20* -45.861 5.21 [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​K = 0.00000e+00 A 4=-5.27117e-08 A 6=-6.27583e-09 A 8= 5.90998e-11 A10=-2.85565e-13 Page 21 K = 0.00000e+00 A 4=-1.00210e-06 A 6= 5.17853e-09 A 8=-2.89728e-11 A10= 6.91598e-14 Page 22 K = 0.00000e+00 A 4= 4.38864e-06 A 6= 3.76368e-09 A 8=-2.97459e-11 A10= 7.92153e-14 Page 23 K = 0.00000e+00 A 4=-4.34639e-06 A 6= 6.23992e-08 A 8=-2.59621e-10 A10= 4.42919e-13 Page 24 K = 0.00000e+00 A 4=-4.37763e-06 A 6= 6.28060e-08 A 8=-2.73663e-10 A10= 5.05780e-13 Various data Focal length 179.74 F-number 3.61 Field of view 6.86 Image height 21.64 Lens length: 203.43 BF 39.06

[0093] Figure 18(A) shows the aberration diagram for tilt imaging 1 in numerical example 6, and Figure 18(B) shows the aberration diagram for tilt imaging 2.

[0094] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d 7 60.69 36.68 60.11 38.82 d12 2.91 26.92 3.49 24.78 d18 2.76 2.76 2.76 2.76 d20 5.21 5.21 5.21 5.21 d22 1.73 1.73 1.73 1.73 d24 2.08 17.66 2.18 15.84 d29 18.07 2.48 17.96 4.30 d31 39.06 39.06 39.06 39.06 Tilt shooting 1 Tilt shooting 2 Ma 2.40 5.34 Mb 3.64 7.63 Zoom lens group data Group Starting surface Focal length 1 1 376.27 2 8 62.69 3 13 -30.83 4 19 59.14 5 21 46.68 6 23 -69.71 7 25 -41.52 8 30 97.76

[0095] [Numerical Example 7] Unit: mm Surface data Surface number r d nd νd 1 54.285 4.47 1.49700 81.5 2 175.488 0.10 3 62.007 6.53 1.49700 81.5 4 -102.174 1.89 1.52918 50.0 5 721.220 0.20 6 1038.719 1.87 1.59134 40.1 7 33.196 6.67 1.49643 82.3 8 219.015 2.56 9 (Aperture) ∞ 5.01 10 -60.570 1.91 1.51735 52.4 11 -83.862 1.93 12 210.422 2.69 1.85843 39.7 13 -352.528 4.20 14 56.588 3.79 1.85935 41.5 15 -197.056 0.99 16* -50.290 1.54 1.49700 81.5 17* -75.257 2.24 18 -93.444 2.00 1.60675 38.4 19 45.839 (Variable) 20 -561.937 1.49 1.73030 54.6 21 22.413 3.85 1.77873 26.3 22 -58.245 1.33 23 -60.248 1.56 1.88984 28.0 24 32.866 (Variable) 25 56.197 1.68 1.84676 23.8 26 41.985 9.51 1.51290 79.2 27 -60.618 37.11 Image plane ∞ Aspherical data Page 16 K = 0.00000e+00 A 4= 5.80635e-05 A 6=-1.95819e-07 A 8= 6.45765e-10 A10=-1.20488e-12 Page 17 K = 0.00000e+00 A 4= 6.03692e-05 A 6=-1.96058e-07 A 8= 7.21946e-10 A10=-1.50213e-12 Various data Focal length 134.80 F-number 3.50 Field of view 9.12 Image height 21.64 Lens length: 135.33 BF 37.11

[0096] Figure 21(A) shows the aberration diagram for tilt imaging 1 of numerical example 7, and Figure 21(B) shows the aberration diagram for tilt imaging 2.

[0097] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d11 1.93 1.93 1.93 1.93 d13 4.20 4.20 4.20 4.20 d17 2.24 2.24 2.24 2.24 d19 3.08 20.98 3.91 20.78 d24 25.14 7.24 24.31 7.44 d27 37.11 37.11 37.11 37.11 Tilt shooting 1 Tilt shooting 2 Ma 9.98 7.28 Mb 4.70 3.22 Zoom lens group data Group starting plane focal length 1 1 131.91 2 12 153.84 3 14 61.61 4 18 -50.41 5 20 -37.31 6 25 65.85

[0098] [Numerical Example 8] Unit: mm Surface data Face number rd nd νd 1 390.101 7.01 1.48749 70.2 2 -109.067 0.18 3 116.523 7.52 1.49652 81.8 4 -96.991 1.97 1.90063 37.4 5 831.126 0.19 6 106.176 6.64 1.74772 27.7 7 -124.914 1.97 1.90065 37.3 8 284.827 6.57 9 56.798 1.94 1.82269 41.3 10 43.696 8.12 11 (aperture) ∞ (variable) 12 53.280 5.18 1.49657 81.8 13 573.096 0.20 14 83.347 1.66 1.72867 31.6 15 41.846 4.81 1.49646 82.0 16 -192.971 (variable) 17 -114.979 1.79 1.83247 44.5 18 50.915 2.15 19 -223.379 3.31 1.92295 18.9 20 -44.681 1.83 1.81604 46.6 21 127.282 (variable) 22 77.085 1.94 1.92304 18.9 23 44.719 3.40 24 103.431 5.56 1.58313 59.4 25* -48.136 1.90 26 54.356 7.37 1.51182 79.1 27 -52.471 6.13 28 96.467 4.64 1.67561 37.6 29 -81.492 1.83 30 -452.895 1.96 1.75157 52.4 31 34.783 3.03 32 -129.503 1.90 1.58313 59.4 33* 1706.616 2.00 34 399.529 1.97 1.92299 18.9 35 45.522 5.72 36 -53.165 5.21 1.88389 20.4 37 -25.000 3.72 1.72881 54.7 38 -859.778 2.84 39 41.728 5.97 1.50919 61.2 40 491.906 (variable) Image plane ∞ Aspherical data Page 25 K = 0.00000e+00 A 4= 2.25167e-06 A 6=-7.24813e-10 Page 33 K = 0.00000e+00 A 4= 6.25777e-06 A 6= 8.45846e-09 A 8= 1.75823e-11 A10=-8.69122e-16 Various data Focal length 179.93 F-number 3.60 Field of view 6.86 Image height 21.64 Lens length: 202.90 BF 31.10

[0099] Figure 24(A) shows the aberration diagram for tilt imaging 1 in numerical example 8, and Figure 24(B) shows the aberration diagram for tilt imaging 2.

[0100] Infinity Maximum magnification Tilt shooting 1 Tilt shooting 2 d11 29.94 5.94 29.44 8.07 d16 3.22 32.99 3.92 31.71 d21 8.49 2.72 8.28 1.86 d23 3.40 3.40 3.40 3.40 d25 1.90 1.90 1.90 1.90 d29 1.83 1.83 1.83 1.83 d33 2.00 2.00 2.00 2.00 d40 31.10 31.10 31.00 31.00 Tilt shooting 1 Tilt shooting 2 Ma 1.55 4.79 Mb 1.65 5.35 Zoom lens group data Group starting plane focal length 1 1 223.22 2 12 71.41 3 17 -30.59 4 22 -118.81 5 24 57.10 6 26 32.26 7 30 -35.07 8 34 -78.35

[0101] [Table 1]

[0102] Each embodiment disclosed includes the following configuration:

[0103] (Composition 1) An optical system capable of tilt imaging, wherein the optical system comprises, arranged in order from the object side, an object-side lens group, a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power. The first lens group and the third lens group move in a direction that includes a component perpendicular to the optical axis for tilt photography. The optical system is characterized in that the object-side lens group and the second lens group are immovable in a direction that includes a component perpendicular to the optical axis for tilt photography.

[0104] (Configuration 2) The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma max Mc max In that case, Ma max / Mc max >0 The optical system according to configuration 1, characterized by satisfying the following conditional equation.

[0105] (Composition 3) When the focal length of the entire optical system is f and the focal length of the first lens group is fa, 0.05 <fa / f<2.00 The optical system according to configuration 1 or 2, characterized by satisfying the following conditional expression.

[0106] (Composition 4) When the focal length of the entire optical system is f and the focal length of the third lens group is fc, -2.00 <fc / f<-0.05 An optical system according to any one of configurations 1 to 3, characterized by satisfying the following conditional expression.

[0107] (Composition 5) The optical system according to any one of configurations 1 to 4, characterized in that the object-side lens group has a positive refractive power.

[0108] (Composition 6) When the Petzval sum of the first lens group is Pa and the Petzval sum of the third lens group is Pc, 0.4 < |Pa| + |Pc| < 12.0 An optical system according to any one of configurations 1 to 5, characterized in that it satisfies the following conditional expression.

[0109] (Composition 7) When the focal length of the entire optical system is f and the back focus of the optical system is Lbk, 0 <Lbk / f<0.65 An optical system according to any one of configurations 1 to 6, characterized in that it satisfies the following conditional expression.

[0110] (Composition 8) When the focal length of the entire optical system is f and the focal length of the second lens group is fb, 0.5 <f / fb<10.0 An optical system according to any one of configurations 1 to 7, characterized by satisfying the following conditional expression.

[0111] (Composition 9) When the lateral magnification of the optical system at its closest focusing point is β, β < -0.25 An optical system according to any one of configurations 1 to 8, characterized by satisfying the following conditional expression.

[0112] (Composition 10) The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma max When the focal length of the first lens group is denoted as fa, 0.01<|Ma max / fa|<0.30 An optical system according to any one of configurations 1 to 9, characterized by satisfying the following conditional expression.

[0113] (Composition 11) The maximum movement of the third lens group in the direction perpendicular to the optical axis is Mc max When the focal length of the third lens group is denoted as fc, 0.01<|Mc max / fc|<0.30 An optical system according to any one of configurations 1 to 10, characterized by satisfying the following conditional expression.

[0114] (Composition 12) When Rfa is the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object within the first lens group, and Rra is the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image within the first lens group, -0.8 < (Rfa + Rra) / (Rra - Rfa) < 0.8 An optical system according to any one of configurations 1 to 11, characterized by satisfying the following conditional expression.

[0115] (Composition 13) When Rfc is the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object within the third lens group, and Rrc is the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image within the third lens group, -0.8 < (Rfc + Rrc) / (Rrc - Rfc) < 0.8 An optical system according to any one of configurations 1 to 12, characterized by satisfying the following conditional expression.

[0116] (Composition 14) The object-side lens group has a first focus group, The optical system according to any one of configurations 1 to 13, characterized in that the first focus group moves in the direction of the optical axis for focusing.

[0117] (Composition 15) It further has a second focus group that moves in the optical axis direction for focusing and is positioned closer to the image than the first focus group, The optical system according to configuration 14, characterized in that the direction of movement of the first focus group during focusing from infinity to the closest distance and the direction of movement of the second focus group during focusing from infinity to the closest distance are in opposite directions.

[0118] (Composition 16) When the amount of movement of the first focus group during focusing from infinity to the closest distance is mLf1, and the amount of movement of the second focus group during focusing from infinity to the closest distance is mLf2, -3.00 <mLf2 / mLf1<-0.10 The optical system according to configuration 15, characterized by satisfying the following conditional equation.

[0119] (Composition 17) An imaging device characterized by having an optical system according to any one of configurations 1 to 16, and an image sensor that receives an image formed by the optical system.

[0120] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence. [Explanation of symbols]

[0121] L0 optical system LF object-side lens group La First Lens Group Lb Second Lens Group Lc third lens group

Claims

1. An optical system capable of tilt imaging, The optical system consists of, arranged in order from the object side, an object-side lens group, a first lens group with positive refractive power, a second lens group with positive refractive power, a third lens group with negative refractive power, and an image-side lens group. The first lens group and the third lens group move in a direction that includes a component perpendicular to the optical axis for tilt photography. The optical system is characterized in that the object-side lens group, the second lens group, and the image-side lens group are immovable in a direction that includes a component perpendicular to the optical axis for tilt imaging.

2. The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma ｍａｘ Mc ｍａｘ In that case, Ma ｍａｘ / ｧc ｍａｘ >0 The optical system according to claim 1, characterized in that it satisfies the following condition.

3. When the focal length of the entire optical system is f and the focal length of the first lens group is fa, 0.05<fa / f<2.00 The optical system according to claim 1, characterized in that it satisfies the following condition.

4. When the focal length of the entire optical system is f and the focal length of the third lens group is fc, -2.00<fc / f<-0.05 The optical system according to claim 1, characterized in that it satisfies the following condition.

5. The optical system according to claim 1, characterized in that the object-side lens group has a positive refractive power.

6. When the Petzval sum of the first lens group is Pa and the Petzval sum of the third lens group is Pc, 0.4<|Pa|+|Pc|<12.0 The optical system according to claim 1, characterized in that it satisfies the following condition.

7. When the focal length of the entire optical system is f and the back focus of the optical system is Lbk, 0<Lbk / f<0.65 The optical system according to claim 1, characterized in that it satisfies the following condition.

8. When the focal length of the entire optical system is f and the focal length of the second lens group is fb, 0.5<f / fb<10.0 The optical system according to claim 1, characterized in that it satisfies the following condition.

9. When the lateral magnification of the optical system at its closest focusing point is β, β＜－０．２５ The optical system according to claim 1, characterized in that it satisfies the following condition.

10. The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma ｍａｘ When the focal length of the first lens group is fa, 0.01<|a ｍａｘ / aa|<030 The optical system according to claim 1, characterized in that it satisfies the following condition.

11. The maximum movement of the third lens group in the direction perpendicular to the optical axis is Mc ｍａｘ When the focal length of the third lens group is denoted as fc, 0.01<|Mc ｍａｘ / fc|<0.30 The optical system according to claim 1, characterized in that it satisfies the following condition.

12. When Rfa is the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object within the first lens group, and Rra is the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image within the first lens group, -0.8<(Rfa+Rra) / (Rra-Rfa)<0.8 The optical system according to claim 1, characterized in that it satisfies the following condition.

13. When Rfc is the paraxial radius of curvature of the object-side lens surface of the lens positioned closest to the object within the third lens group, and Rrc is the paraxial radius of curvature of the image-side lens surface of the lens positioned closest to the image within the third lens group, -0.8<(Rfc+Rrc) / (Rrc-Rfc)<0.8 The optical system according to claim 1, characterized in that it satisfies the following condition.

14. The object-side lens group has a first focus group, The optical system according to claim 1, characterized in that the first focus group moves in the direction of the optical axis for focusing.

15. The optical system according to claim 14, further comprising a second focus group that moves in the optical axis direction for focusing and is positioned closer to the image than the first focus group, characterized in that the direction of movement of the first focus group in focusing from infinity to the closest distance and the direction of movement of the second focus group in focusing from infinity to the closest distance are opposite.

16. When the amount of movement of the first focus group during focusing from infinity to the closest distance is mLf1, and the amount of movement of the second focus group during focusing from infinity to the closest distance is mLf2, -3.00<mLf2 / mLf1<-0.10 The optical system according to claim 15, characterized in that it satisfies the following conditional expression.

17. Let the maximum amount of movement in the direction perpendicular to the optical axis of the first lens group be Ma ｍａｘ and the maximum amount of movement in the direction perpendicular to the optical axis of the third lens group be Mc ｍａｘ When this is the case Ma ｍａｘ / ｧc ｍａｘ >0 The optical system according to any one of claims 3 to 16, characterized in that it satisfies the following conditional expression.

18. When the focal length of the entire optical system is f and the focal length of the first lens group is fa, 0.05<fa / f<2.00 The optical system according to any one of claims 4 to 16, characterized in that it satisfies the following conditional expression.

19. When the focal length of the entire optical system is f and the focal length of the third lens group is fc, -2.00<fc / f<-0.05 The optical system according to any one of claims 5 to 16, characterized in that it satisfies the following conditional expression.

20. The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma ｍａｘ Mc ｍａｘ When the focal length of the entire optical system is f and the focal length of the first lens group is fa, Ma ｍａｘ / ｧc ｍａｘ >0 0.05<fa / f<2.00 The optical system according to any one of claims 4 to 16, characterized in that it satisfies the following conditional expression.

21. The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma ｍａｘ Mc ｍａｘ When the focal length of the entire optical system is f and the focal length of the third lens group is fc, Ma ｍａｘ / ｧc ｍａｘ >0 -2.00<fc / f<-0.05 The optical system according to any one of claims 5 to 16, characterized in that it satisfies the following conditional expression.

22. When the total focal length of the optical system is f, the focal length of the first lens group is fa, and the focal length of the third lens group is fc, 0.05<fa / f<2.00 -2.00<fc / f<-0.05 The optical system according to any one of claims 5 to 16, characterized in that it satisfies the following conditional expression.

23. The maximum movement of the first lens group in the direction perpendicular to the optical axis is Ma ｍａｘ Mc ｍａｘ When the total focal length of the optical system is f, the focal length of the first lens group is fa, and the focal length of the third lens group is fc, Ma ｍａｘ / ｧc ｍａｘ >0 0.05<fa / f<2.00 -2.00<fc / f<-0.05 The optical system according to any one of claims 5 to 16, characterized in that it satisfies the following conditional expression.

24. An imaging device comprising an optical system according to any one of claims 1 to 16, and an image sensor that receives an image formed by the optical system.

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