Lens device and imaging device

Abstract

This lens device is compact yet capable of magnified photography from infinity to 1:1 magnification, and offers high optical performance. [Solution] The lens device consists of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, arranged in order from the object side to the image side. During focusing, the spacing between adjacent lens groups changes, the first lens group does not move, while the second and fourth lens groups move, appropriately setting the focal length of the entire system, the focal length of the third lens group, and the focal length of the fourth lens group.

Description

[Technical Field]

[0001] The present disclosure relates to a lens apparatus and an image pickup apparatus. [Background Art]

[0002] In recent years, macro lenses are known that can photograph an object at infinity and also enable magnified photography where the photographing magnification at close-up photography is 1×. Particularly for macro lenses having a focal length from standard to medium telephoto, a so-called telephoto type photographing optical system is known, in which an optical system having positive refractive power is disposed on the object side and an optical system having negative refractive power is disposed on the image side. Patent Documents 1 and 2 disclose a macro lens that includes, in order from the object side to the image side, first to fifth lens groups having refractive powers of positive, negative, positive, positive, and negative, and performs focusing with the second lens group and the fourth lens group. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Laid-Open No. 2020-060661 [Patent Document 2] Japanese Patent Laid-Open No. 2020-064123 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] In recent years, there has been a strong demand for optical systems used in image pickup apparatuses to have high optical performance with a short distance between an object and the lens (minimum photographing distance) at the closest photographing distance while the entire optical system is compact. In order to obtain favorable optical performance while achieving downsizing of the entire optical system, it is important to appropriately set the refractive power and configuration of each lens group, the movement conditions associated with focusing of each lens group, and the like.

[0005] The macro lens disclosed in Patent Document 1 is difficult to miniaturize because the refractive power of the fourth lens group, which is the focusing group, is weak relative to the focal length of the entire system. The macro lens disclosed in Patent Document 2 is difficult to miniaturize because the refractive power of the third lens group is weak relative to the focal length of the entire system.

[0006] Therefore, the purpose of this disclosure is to provide a lens device that is compact, capable of magnified photography from infinity to 1:1 magnification, and possessing high optical performance. [Means for solving the problem]

[0007] A lens device according to one aspect of this disclosure has, in order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the distance between adjacent lens groups changes during focusing, and during focusing, the first lens group does not move, the second lens group and the fourth lens group move, and when the focal length of the entire system is f, the focal length of the third lens group L3 is f3, and the focal length of the fourth lens group L4 is f4, 0.44 <f3 / f<0.8 0 <f4 / f<0.72 It is characterized by satisfying the following conditions.

[0008] Another aspect of the present disclosure is a lens device having, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the spacing between adjacent lens groups changes during focusing, characterized in that the first lens group does not move, while the second and fourth lens groups move during focusing. [Effects of the Invention]

[0009] This disclosure provides a lens device that is compact yet capable of magnified photography from infinity to 1:1 magnification, and possesses high optical performance. [Brief explanation of the drawing]

[0010] [Figure 1] These are cross-sectional views of the lens device according to Example 1, showing (a) when in focus at infinity and (b) when in focus at the closest point. [Figure 2] This diagram shows the aberrations of the lens device according to Example 1 at (a) infinity focus and (b) closest focus. [Figure 3] These are cross-sectional views of the lens device according to Example 2 at (a) in focus at infinity and (b) at closest focus. [Figure 4] This is an aberration diagram of the lens device according to Example 2 at (a) infinity focus and (b) closest focus. [Figure 5] These are cross-sectional views of the lens device according to Example 3, showing (a) when in focus at infinity and (b) when in focus at the closest point. [Figure 6] This is an aberration diagram of the lens device according to Example 3 at (a) infinity focus and (b) closest focus. [Figure 7] These are cross-sectional views of the lens device according to Example 4, showing (a) when in focus at infinity and (b) when in focus at the closest point. [Figure 8] This is an aberration diagram of the lens device according to Example 4 at (a) in focus at infinity and (b) at closest focus. [Figure 9] This is a schematic diagram of the main parts of the imaging device according to the embodiment. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. The lens apparatus of each embodiment is a photographing lens apparatus used in imaging apparatuses such as still cameras, video cameras, digital still cameras, silver halide film cameras, TV cameras, in-vehicle cameras, and surveillance cameras. The lens apparatus of each embodiment can also be used as a projection optical system for a projection apparatus (projector).

[0012] In recent years, macro lenses capable of photographing an object at infinity and also enabling magnified photography in which the photographing magnification at close-up photography is 1× are known. Particularly among macro lenses having a focal length from standard to medium-telephoto, a so-called telephoto type photographing optical system is known, in which an optical system having positive refractive power is disposed on the object side, and an optical system having negative refractive power is disposed on the image side. Telephoto type optical systems are used, for example, in telephoto lenses of zoom lenses.

[0013] Furthermore, in digital cameras and video cameras, the pixel count of solid-state imaging devices such as CCD and CMOS sensors has been increasing, so that photographing lenses are required to have high optical performance including correction of chromatic aberration, while size reduction of imaging apparatuses has been progressing.

[0014] In recent years, there has been a strong demand for optical systems used in imaging apparatuses to be small in size as a whole, have a short distance between an object and a lens at closest photography (minimum shooting distance), and exhibit high optical performance. To obtain favorable optical performance while reducing the size of the entire optical system, it is important to appropriately set the refractive power and configuration of each lens group, the movement conditions associated with focusing of each lens group, and the like. The present disclosure aims to provide a lens apparatus that is small in size and has high optical performance from infinity photography to closest photography.

[0015] The lens apparatus of the present disclosure comprises, in order from the object side to the image side: a first lens group L1 having positive refractive power (optical power = reciprocal of focal length), a second lens group L2 having negative refractive power, a third lens group having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having negative refractive power, wherein the distance between adjacent lens groups changes during focusing. During focusing from infinity to a close distance, the second lens group L2 moves toward the image side and the fourth lens group L4 moves toward the object side along mutually different tracks in the optical axis direction. The first lens group L1 does not move during focusing.

[0016] In order to achieve the above object, the lens apparatus of the present disclosure, when the focal length of the entire system is f, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.44 < f3 / f < 0.8 ···(1) 0 < f4 / f < 0.72 ···(2) satisfies the following condition.

[0017] In order to favorably correct aberrations over the entire focusing range, the focusing lens group is configured by a second lens group L2 having negative refractive power disposed on the object side of an aperture stop SP, and a fourth lens group L4 including a lens group having positive refractive power disposed on the image side of the aperture stop SP. This makes it possible to suppress fluctuations in spherical aberration and chromatic aberration of magnification caused by focusing in the second lens group L2, and also suppress fluctuations in field curvature and chromatic aberration of magnification in the fourth lens group L4.

[0018] The first lens group L1 has a positive lens closest to the object side. Disposing a positive lens closest to the object side is advantageous for correcting axial chromatic aberration. Further, in the first lens group L1, at least two positive lenses are arranged consecutively in order from the closest object side to the image side. With this configuration, it is possible to effectively converge an on-axis light flux to enable downsizing of the entire system, while favorably correcting various on-axis aberrations such as spherical aberration and coma.

[0019] The second lens group L2 includes at least two negative lenses. With this configuration, while achieving weight reduction of the second lens group L2 which is the focusing lens group, it becomes easy to make a light flux incident on the third lens group L3 parallel to the optical axis, and fluctuations in spherical aberration caused by focusing can be suppressed.

[0020] The third lens group L3 has one positive lens closest to the image sensor. This configuration allows for miniaturization of the entire system by effectively focusing the axial light beam, while also suppressing coma aberration and field curvature variations associated with vibration isolation when some of the lens groups in the third lens group L3 are used as an image stabilization group.

[0021] The fourth lens group L4 has at least one positive lens element. This configuration allows for miniaturization of the entire system by effectively focusing the axial light beam, while suppressing variations in various aberrations such as field curvature and chromatic aberration associated with focusing.

[0022] The fifth lens group L5 has the negative lens closest to the object. Having the fifth lens group L5 with the negative lens closest to the object allows for effective divergence of off-axis light beam, which is advantageous for miniaturizing the entire system. Furthermore, if the fifth lens group L5 has at least two negative lenses, off-axis aberrations such as chromatic aberration and distortion can be corrected more effectively.

[0023] Conditional equation (1) defines the ratio of the focal length f of the entire system to the focal length f3 of the third lens group L3, and is a condition for achieving both miniaturization of the entire system and correction of optical performance. If the upper limit of conditional equation (1) is exceeded, the refractive power of the third lens group L3 weakens, which is advantageous for suppressing spherical aberration and axial chromatic aberration generated by the axial beam, but it leads to an increase in the size of the entire system, which is undesirable. If the lower limit of conditional equation (1) is exceeded, the refractive power of the third lens group L3 strengthens, which is advantageous for miniaturizing the entire system, but it makes it difficult to suppress spherical aberration and axial chromatic aberration, which is undesirable.

[0024] Condition (2) is an equation that defines the ratio of the focal length f of the entire system to the focal length f4 of the fourth lens group L4, and is a condition for miniaturizing the entire system and suppressing changes in optical performance due to focusing. If the upper limit of condition (2) is exceeded, the refractive power of the fourth lens group L4, which is the focusing lens group, becomes weaker, making it easier to suppress fluctuations in field curvature and chromatic aberration associated with focusing. However, the distance that the fourth lens group L4 moves during focusing becomes longer, leading to an increase in the size of the entire system, which is undesirable. If the lower limit of condition (2) is exceeded, the refractive power of the fourth lens group L4, which is the focusing lens group, becomes stronger, shortening the distance that the fourth lens group L4 moves during focusing. This is advantageous for miniaturizing the entire system, but it becomes difficult to suppress fluctuations in field curvature and chromatic aberration associated with focusing, which is undesirable.

[0025] In each embodiment, it is preferable to set the numerical ranges of conditional expressions (1) and (2) as follows. 0.46 <f3 / f<0.79 ···(1a) 0.15 <f4 / f<0.70 ···(2a) By satisfying condition (1a), axial chromatic aberration caused by axial light beam at the closest focusing point is easily suppressed. By satisfying condition (2a), it is easier to achieve both lateral chromatic aberration caused by off-axis light beam at the closest focusing point and miniaturization of the entire system. More preferably, the numerical ranges of the conditional expressions (1a) and (2a) should be set as follows. 0.48 <f3 / f<0.78 ···(1b) 0.30 <f4 / f<0.68 ···(2b)

[0026] As described above, by appropriately configuring each lens group and satisfying conditions (1) and (2), a lens system can be realized that enables everything from photographing objects at infinity to magnified photography with a 1:1 magnification, and the entire system is compact with high optical performance.

[0027] In each embodiment, it is even more preferable that one or more of the following conditional expressions (3) to (16) be satisfied. -0.50 <f5 / f<-0.15 ···(3) -0.85 <f5 / f3<-0.30 ···(4) -0.80 <f5 / f4<-0.30 ···(5) 0.65 <f3 / f4<2.00 ···(6) -0.80 <f2 / f3<-0.35 ···(7) 0 <f / |f12|<0.30 ···(8) 0.40 <f3B / f3A<5.00 ···(9) 0.80 <f5A / f5<1.60 ···(10) 6.0 <sk / TL<14.0 ···(11) 0.90 <MD2 / TL<1.80 ···(12) 0.80 <MD4 / TL<1.60 ···(13) -5.00 <ES2<-3.00 ···(14) 2.00 <ES4<3.50 ···(15) 0.70 <G5ASF<2.00 ···(16)

[0028] Here, f2 is the focal length of the second lens group L2, f5 is the focal length of the fifth lens group L5, and f12 is the combined focal length of the first lens group L1 and the second lens group L2 when focused at infinity. f3A is the focal length of the lens element G3A closest to the object in the third lens group L3, and f3B is the focal length of all lens elements G3B closer to the image than lens element G3A in the third lens group L3. f5A is the focal length of the lens element G5A closest to the object in the fifth lens group L5. sk is the back focus when focused at infinity, and TL is the total optical length of the entire system. MD2 is the distance the second lens group L2 moves along the optical axis when focusing from infinity to the closest focus, and MD4 is the distance the fourth lens group L4 moves along the optical axis when focusing from infinity to the closest focus. ES2 is the focus sensitivity of the second lens group L2 at infinity focus, and ES4 is the focus sensitivity of the fourth lens group L4 at infinity focus. G5ASF is the shape factor of the lens element G5A closest to the object, which is included in the fifth lens group L5.

[0029] The shape factor SF is the shape factor of lens L, where fL is the focal length of lens L, R1 is the radius of curvature of the object-side surface, and R2 is the radius of curvature of the image-side surface. SF = sgn(fL) × (R² + R¹) / (R² - R¹) It is defined by the following formula. In the case of an aspherical shape, it means the radius of the reference quadratic surface. sgn(fL) is a sign function that is +1 if fL is a positive value, and -1 if fL is a negative value.

[0030] The Abbe number νd is given by the Fraunhofer lines d, F, and C, where Nd, NF, and NC are the refractive indices of the d, F, and C lines, respectively. νd = (Nd-1) / (NF-NC) It is defined as follows.

[0031] Here, back focus is the distance from the vertex of the lens surface closest to the image to the image plane. When an optical element with extremely weak refractive power is placed between the lens device and the image sensor, the back focus value used is the value obtained by converting the refractive power of the optical element placed between the lens device and the image sensor to air equivalent.

[0032] Furthermore, focus sensitivity is defined as the lateral magnification of the moving lens group i at infinity focus, where βi is the lateral magnification of the moving lens group i and βr is the lateral magnification of the lens group r positioned closer to the image than the moving lens group i. ESi=(1-βi 2 )×βr 2 It is represented as follows.

[0033] Conditional equation (3) defines the ratio of the focal length f5 of the fifth lens group L5 to the total focal length f of the entire system, aiming to achieve both miniaturization of the entire system and high optical performance. Exceeding the upper limit of condition (3) is advantageous for miniaturization, but it is undesirable because it becomes difficult to correct aberrations such as spherical aberration that occur in the positive lens group located on the object side of the fifth lens group L5. Exceeding the lower limit of condition (3) is advantageous in suppressing distortion and chromatic aberration mainly occurring in off-axis light beams, but it is undesirable because it weakens the telephoto effect and increases the overall optical length of the system.

[0034] Conditional equation (4) defines the ratio of the focal length f5 of the fifth lens group L5 to the focal length f3 of the third lens group L3, aiming to achieve both miniaturization of the entire system and high optical performance. Exceeding the upper limit of condition (4) is advantageous in suppressing field curvature and chromatic aberration, which mainly occur in off-axis light beams, but it is undesirable because it weakens the telephoto effect and increases the overall optical length. If the lower limit of condition (4) is exceeded, the telephoto effect intensifies, which is advantageous because it shortens the overall optical length of the system. However, this is undesirable because it becomes difficult to suppress spherical aberration and axial chromatic aberration, which mainly occur in the axial beam.

[0035] Conditional equation (5) defines the ratio of the focal length f5 of the fifth lens group L5 to the focal length f4 of the fourth lens group L4, aiming to achieve both miniaturization of the entire system and high optical performance. Exceeding the upper limit of condition (5) is advantageous in suppressing field curvature and chromatic aberration, which mainly occur in off-axis light beams, but it is undesirable because it weakens the telephoto effect and increases the overall optical length. If the lower limit of condition (5) is exceeded, the telephoto effect intensifies, which is advantageous because it shortens the overall optical length of the system. However, this is undesirable because it becomes difficult to suppress spherical aberration and axial chromatic aberration, which mainly occur in the axial beam.

[0036] Conditional equation (6) defines the ratio of the focal length f3 of the third lens group L3 to the focal length f4 of the fourth lens group L4, aiming to achieve both miniaturization of the entire system and high optical performance. If the upper limit of condition (6) is exceeded, in order to achieve miniaturization, it is necessary to shorten the focal length f4 of the fourth lens group L4, which is the focusing lens group. This is undesirable because it becomes difficult to suppress fluctuations in field curvature and chromatic aberration when focusing. Exceeding the lower limit of condition (6) is advantageous for miniaturization, but it is undesirable because it becomes difficult to suppress spherical aberration and axial chromatic aberration, which mainly occur in the axial beam.

[0037] Conditional equation (7) defines the ratio of the focal length f2 of the second lens group L2 to the focal length f3 of the third lens group L3, aiming to achieve both miniaturization of the entire system and high optical performance. If the upper limit of condition (7) is exceeded, it is advantageous in suppressing fluctuations in spherical aberration when focusing, but it is undesirable because the travel distance of the second lens group L2, which is the focusing lens group, when focusing becomes longer, and the overall optical length of the system becomes longer. If the lower limit of condition (7) is exceeded, the travel distance of the second lens group L2, which is the focusing lens group, becomes shorter when in focus, and the overall optical length of the system becomes shorter. This is advantageous for miniaturization, but it is undesirable because it becomes difficult to suppress fluctuations in spherical aberration when in focus.

[0038] Conditional equation (8) defines the ratio of the absolute value of the combined focal length f of the first lens group L1 and the second lens group L2 at infinity focus to the total focal length f12, aiming to achieve both miniaturization of the entire system and high optical performance. Exceeding the upper limit of condition (8) is advantageous for miniaturization, but it is undesirable because it makes it difficult to suppress various aberrations such as spherical aberration that occur in the first lens group L1 and the second lens group L2. Also, if part or all of the third lens group L3 is made into an anti-vibration group, the angle of the light beam incident on the third lens group L3 becomes steeper, making it difficult to ensure optical performance when in focus, which is undesirable. Exceeding the lower limit of condition (8) is advantageous for suppressing various aberrations such as spherical aberration that occur in the first lens group L1 and the second lens group L2, but it is undesirable because it makes miniaturization difficult.

[0039] Conditional equation (9) defines the ratio of the focal length f3A of the lens element G3A closest to the object in the third lens group L3 to the focal length f3B of all lens elements G3B on the image side of lens element G3A, aiming to achieve both miniaturization of the entire system and high optical performance. If the upper limit of condition (9) is exceeded, using the image stabilization group for lens element G3A is advantageous for ensuring optical performance when focusing, but it is undesirable because miniaturization becomes difficult. Exceeding the lower limit of condition (9) is advantageous for miniaturization, but it is undesirable because it becomes difficult to suppress various aberrations such as spherical aberration that occur in the lens element G3B.

[0040] Conditional equation (10) defines the ratio of the focal length f5A of the lens element G5A closest to the object in the fifth lens group L5 to the focal length f5 of the fifth lens group L5, aiming to achieve both miniaturization of the entire system and high optical performance. If the upper limit of condition (10) is exceeded, the effect of boosting the off-axis luminous flux weakens, which is advantageous for suppressing distortion and chromatic aberration, but it is undesirable because it makes miniaturization difficult. If the lower limit of condition (10) is exceeded, the effect of boosting the off-axis luminous flux intensifies, which is advantageous for miniaturization, but it is undesirable because it makes it difficult to suppress distortion and chromatic aberration.

[0041] Condition (11) defines the ratio of the back focus sk at infinity focus to the total optical length TL of the entire system at infinity focus, and is a condition for achieving both miniaturization of the entire system and securing the travel distance of the focusing lens group. If the upper limit of condition (11) is exceeded, the degree of freedom in arranging mechanical components in the mount section increases, but it becomes difficult to secure the travel distance of the focus lens group, which is undesirable. If the lower limit of condition (11) is exceeded, it becomes easier to secure the travel distance of the focus lens group, but it becomes difficult to properly position the mechanical components in the mount area, which is undesirable.

[0042] Conditional equation (12) defines the ratio of the distance MD2 over which the second lens group L2 moves along the optical axis when focusing from infinity to the closest distance, to the total optical length TL of the entire system. This condition is necessary to achieve both miniaturization of the entire system and suppression of changes in optical performance during focusing. Exceeding the upper limit of condition (12) is advantageous in suppressing fluctuations in various aberrations such as spherical aberration when in focus, but it is undesirable because it leads to an increase in the overall size of the system. Exceeding the lower limit of condition (12) is advantageous for miniaturizing the entire system, but it is undesirable because it becomes difficult to suppress fluctuations in various aberrations such as field curvature when in focus.

[0043] Conditional equation (13) defines the ratio of the distance MD4, the distance the fourth lens group L4 moves along the optical axis when focusing from infinity to the closest focusing distance, to the total optical length TL of the entire system. This condition is necessary to achieve both miniaturization of the entire system and suppression of changes in optical performance during focusing. Exceeding the upper limit of condition (13) is advantageous in suppressing fluctuations in various aberrations such as field curvature when focusing, but it is undesirable because it leads to an increase in the overall size of the system. Exceeding the lower limit of condition (13) is advantageous for miniaturizing the entire system, but it is undesirable because it becomes difficult to suppress fluctuations in various aberrations such as spherical aberration when in focus.

[0044] Conditional equation (14) represents the focus sensitivity ES2 of the second lens group L2 when focused at infinity, and is a condition for achieving both miniaturization of the entire system and suppression of changes in optical performance due to focusing. If the upper limit of condition (14) is exceeded, miniaturization at infinity focus becomes easier, but it becomes difficult to suppress the fluctuations in field curvature and distortion aberrations at focus, mainly caused by off-axis rays, which is undesirable. Furthermore, it becomes difficult to control the focus lens group with high precision, which is also undesirable. Exceeding the lower limit of condition (14) is advantageous in suppressing fluctuations in optical performance during focusing, but it is undesirable because it makes miniaturization difficult. Furthermore, it becomes difficult to operate the focusing lens group at high speed, which is also undesirable.

[0045] Conditional equation (15) represents the focus sensitivity ES4 of the fourth lens group L4 when focused at infinity, and is a condition for achieving both miniaturization of the entire system and suppression of changes in optical performance due to focusing. If the upper limit of condition (15) is exceeded, miniaturization at infinity focus becomes easier, but it becomes difficult to suppress the fluctuations in field curvature and distortion aberrations at focus, mainly caused by off-axis rays, which is undesirable. Furthermore, it becomes difficult to control the focus lens group with high precision, which is also undesirable. Exceeding the lower limit of condition (15) is advantageous in suppressing fluctuations in optical performance during focusing, but it is undesirable because it makes miniaturization difficult. Furthermore, it becomes difficult to operate the focusing lens group at high speed, which is also undesirable.

[0046] Conditional equation (16) defines the shape factor G5ASF of the lens components constituting the third lens group L3, and is a condition aimed at miniaturization and suppressing changes in optical performance during focusing. When the value of conditional equation (16) is -1 and the lens components have a negative refractive index, the lens components have a plano-concave shape with the concave surface facing the object. If the upper limit of condition (16) is exceeded, the curvature of the object side surface of the lens component increases, making it easier to suppress fluctuations in spherical aberration generated by the on-axial light beam on the object side surface when in focus. However, the lens shape becomes biconcave, making it difficult to suppress field curvature generated by the off-axial light beam when in focus, which is undesirable. If the lower limit of condition (16) is exceeded, the curvature of the object side surface of the lens component becomes smaller, making it difficult to suppress the fluctuation of spherical aberration caused by focusing in the axial light beam, which is undesirable. Furthermore, the smaller curvature results in a meniscus-shaped lens, which is undesirable because it makes lens processing and shaping difficult.

[0047] The first lens group L1 preferably has two or more positive lenses and one negative lens, in order from the object side. This configuration increases the degree of freedom in selecting the glass material for the positive lenses and allows for good correction of various aberrations such as chromatic aberration.

[0048] The second lens group L2 is positioned closer to the object than the aperture diaphragm SP, and it is desirable that it has two or more negative lenses and one positive lens. This allows the light beam focused by the first lens group L1 to diverge, and the light beam to be afocally incident on the third lens group L3, making it easier to suppress fluctuations in spherical aberration due to focusing.

[0049] Furthermore, it is desirable that the second lens group L2 has an aspherical lens with the most negative refractive power on the object side. This makes it easier to miniaturize the lens while effectively correcting variations in field curvature due to focusing. However, having two or more aspherical lenses is advantageous for correcting field curvature and distortion, but it makes lens molding difficult and makes it difficult to ensure optical performance, so it is undesirable.

[0050] It is desirable to position the aperture diaphragm SP between the second lens group L2 and the third lens group L3. This allows the exit pupil to be positioned on the object side, facilitating miniaturization of the entire system. Furthermore, since it becomes possible to place more lenses on the image side of the aperture diaphragm SP, it becomes easier to suppress field curvature and chromatic aberration variations caused by focusing, mainly due to off-axis rays.

[0051] The third lens group L3 is positioned closer to the image than the aperture diaphragm SP, and preferably consists of a cemented lens with one positive lens and one negative lens, and one positive lens. This makes it easier to suppress spherical aberration and axial chromatic aberration, which are mainly caused by axial light beam, while also miniaturizing the front system.

[0052] The fourth lens group L4 preferably has at least one positive lens and one negative lens. This makes it possible to suppress field curvature and chromatic aberration caused by focusing, which are mainly generated by off-axis light beams.

[0053] It is preferable that the fifth lens group L5 has a negative lens closest to the object. This allows for effective divergence of off-axis light beam, making it easier to achieve both weight reduction of the fourth lens group L4 (the focusing lens group) and miniaturization of the entire system. It is also preferable that it has at least two negative lenses and at least one positive lens. This allows for good correction of various aberrations such as distortion and chromatic aberration.

[0054] Furthermore, by fixing the fifth lens group L5 relative to the image plane position during focusing, the generation of dust and other debris, which can be a problem when removing interchangeable lenses, can be reduced, making it easier to ensure durability. In addition, it is desirable to provide a lens with an image-side convex shape at the closest to the image sensor. With this configuration, securing back focus becomes relatively easy, and unwanted light (ghosting) caused by the image sensor can be suppressed.

[0055] In the lens apparatus of each embodiment, vibration isolation can also be performed by moving any entire lens group or a part thereof as a vibration isolation group in a direction that includes a component perpendicular to the optical axis, or by rotating (oscillating) it in an in-plane direction including the optical axis. In particular, in the lens apparatus of Embodiments 1 to 4, it is preferable to perform vibration isolation by moving the entire third lens group L3 or a part thereof in a direction that includes a component perpendicular to the optical axis. It is even more preferable to perform vibration isolation at the lens element of the third lens group L3 that is closest to the object. There are no particular restrictions on the number or shape of lenses in the vibration isolation group. Furthermore, it is preferable that the lenses have a positive refractive power. More preferably, the vibration isolation group is a cemented lens consisting of one positive lens and one negative lens.

[0056] It is preferable that the lens apparatus in each embodiment does not include a diffractive optical element. While providing a diffractive optical element in the lens apparatus is advantageous from the viewpoint of chromatic aberration correction, it is undesirable because diffraction flare occurs in the diffractive optical element.

[0057] More preferably, the numerical ranges of conditional expressions (3) to (13) should be set as follows. -0.45 <f5 / f<-0.20 ···(3a) -0.80 <f5 / f3<-0.35 ···(4a) -0.75 <f5 / f4<-0.35 ···(5a) 0.70 <f3 / f4<1.90 ···(6a) -0.75 <f2 / f3<-0.40 ···(7a) 0.02 <f / |f12|<0.25 ···(8a) 0.50 <f3B / f3A<4.80 ···(9a) 0.85 <f5A / f5<1.55 ···(10a) 7.0 <sk / TL<13.0 ···(11a) 0.95 <MD2 / TL<1.70 ···(12a) 0.90 <MD4 / TL<1.50 ···(13a) -4.50 <ES2<-3.40 ···(14a) 2.40 <ES4<3.20 ···(15a) 0.75 <G5ASF<1.80 ···(16a)

[0058] Furthermore, it is even better if the numerical ranges of conditional expressions (3a) to (13a) are set as follows, as this will synergistically enhance the aforementioned effects. -0.40 <f5 / f<-0.23 ···(3b) -0.77 <f5 / f3<-0.37 ···(4b) -0.73 <f5 / f4<-0.38 ···(5b) 0.72 <f3 / f4<1.85 ···(6b) -0.72 <f2 / f3<-0.43 ···(7b) 0.03 <f / |f12|<0.22 ···(8b) 0.60 <f3B / f3A<4.60 ···(9b) 0.90 <f5A / f5<1.50 ···(10b) 8.0 <sk / TL<12.5 ···(11b) 1.00 <MD2 / TL<1.65 ···(12b) 0.95 <MD4 / TL<1.45 ···(13b) -4.30 <ES2<-3.70 ···(14b) 2.60 <ES4<3.00 ···(15b) 0.80 <G5ASF<1.70 ···(16b) Examples 1 to 4 of the lens apparatus according to this disclosure will be described below with reference to the attached drawings. [Examples]

[0059] Figure 1 shows cross-sectional views of the lens device of Example 1 at (a) infinity focus and (b) closest focus (magnification β = -1.0). In the cross-sectional view of the lens device, the left side is the object side (front) and the right side is the image side (rear). Also, in the lens cross-sectional view, if i is the order of the lens group from the object side, then Li is the i-th lens group. The arrows indicated in the cross-sectional view of each lens device show the direction of movement of the lens group when focusing from infinity to near distance.

[0060] SP is the aperture diaphragm that determines (limits) the light beam at the open F-number (Fno). IP is the image plane, and when used as the imaging optical system for a video camera or digital still camera, the imaging surface of a solid-state image sensor (photoelectric conversion element) such as a CCD sensor or CMOS sensor is placed there. When used as the imaging optical system for a silver halide film camera, the photosensitive surface corresponding to the film plane is placed there. The same applies to the following embodiments.

[0061] The lens apparatus of Example 1 has, in order from the object side to the image side, a first lens group L1 with positive refractive power, a second lens group L2 with negative refractive power, a third lens group L3 with positive refractive power, a fourth lens group L4 with positive refractive power, and a fifth lens group L5 with negative refractive power. The lens apparatus of Example 1 has an aperture ratio of approximately 2.9. During focusing from infinity to close range, the second lens group L2 moves towards the image, and the fourth lens group L4 moves towards the object, each following a different trajectory. The first lens group L1 does not move during focusing.

[0062] The first lens group L1 consists of, in order from the object side to the image side, a positive lens, a cemented lens of a positive and a negative lens, and a meniscus positive lens that is convex towards the object side. The second lens group L2 consists of a negative lens, a cemented lens comprising a meniscus negative lens convex to the object side, and a meniscus positive lens convex to the object side, arranged in order from the object side to the image side. The third lens group L3 consists of a cemented lens comprising a positive lens and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side, and a concave meniscus positive lens on the object side. The fourth lens group L4 consists of a positive lens and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side. The fifth lens group L5 consists of, in order from the object side to the image side, a negative lens, a concave meniscus positive lens on the object side, a concave meniscus negative lens on the object side, and a concave meniscus positive lens on the object side. The aperture diaphragm SP is positioned adjacent to the object side of the third lens group L3.

[0063] Figure 2 shows the aberration diagrams of the lens device of Example 1 at (a) infinity focus and (b) closest focus (magnification β = -1.0). In the aberration diagram, Fno represents the F-number, and ω represents the half-angle of view (degrees), which is the angle of view determined by ray tracing. In the spherical aberration diagram, d represents the d-line (wavelength 587.56 nm), and g represents the g-line (wavelength 435.835 nm). In the astigmatism diagram, ΔS represents the aberration at the sagittal image plane at the d-line, and ΔM represents the aberration at the meridional image plane at the d-line. Distortion aberration is shown for the d-line. In the chromatic aberration diagram, g represents the g-line. All aberrations are well corrected.

[0064] Table 1 shows the numerical values ​​in Example 1 corresponding to conditions (1) to (16). The lens device according to Example 1 satisfies conditions (1) to (16), is compact, yet enables magnified photography from infinity to 1:1 magnification, and possesses high optical performance. [Examples]

[0065] Figure 3 shows cross-sectional views of the lens device of Example 2 at (a) infinity focus and (b) closest focus (magnification β = -1.0). Figure 4 shows aberration diagrams of the lens device of Example 2 at (a) infinity focus and (b) closest focus (magnification β = -1.0). The lens device of Example 2 is a lens device with an aperture ratio of approximately 2.9.

[0066] The lens device of Example 2 has, in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having negative refractive power. During focusing from infinity to close range, the second lens group L2 moves towards the image, and the fourth lens group L4 moves towards the object, each following a different trajectory. The first lens group L1 does not move during focusing.

[0067] The first lens group L1 consists of, in order from the object side to the image side, a positive lens, a cemented lens of a positive and a negative lens, and a meniscus positive lens that is convex towards the object side. The second lens group L2 consists of a negative lens, a cemented lens comprising a meniscus negative lens convex to the object side, and a meniscus positive lens convex to the object side, arranged in order from the object side to the image side. The third lens group L3 consists of a positive lens, a cemented lens made up of a concave meniscus negative lens on the object side, and a concave meniscus positive lens on the object side, arranged in order from the object side to the image side. The fourth lens group L4 consists of a positive lens and a cemented lens made up of a positive lens and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side. The fifth lens group L5 consists of a negative lens, a positive lens, another negative lens, and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side. The aperture diaphragm SP is positioned adjacent to the object side of the third lens group L3.

[0068] Figure 4 shows the aberration diagrams of the lens device of Example 2 at (a) infinity focus and (b) closest focus (magnification β = -1.0). All aberrations are well corrected. Table 1 shows the numerical values ​​in Example 2 corresponding to conditions (1) to (16). The lens device according to Example 2 satisfies conditions (1) to (16), is compact, yet enables magnified photography from infinity to 1:1 magnification, and possesses high optical performance. [Examples]

[0069] Figure 5 shows cross-sectional views of the lens device of Example 3 at (a) infinity focus and (b) closest focus (magnification β = -1.0). Figure 6 shows aberration diagrams of the lens device of Example 3 at (a) infinity focus and (b) closest focus (magnification β = -1.0). The lens device of Example 3 is a lens device with an aperture ratio of approximately 2.9.

[0070] The lens device of Example 3 has, in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having negative refractive power. During focusing from infinity to close range, the second lens group L2 moves towards the image, and the fourth lens group L4 moves towards the object, each following a different trajectory. The first lens group L1 does not move during focusing.

[0071] The first lens group L1 consists of, in order from the object side to the image side, a positive lens, a cemented lens of a positive and a negative lens, and a meniscus positive lens that is convex towards the object side. The second lens group L2 consists of a negative lens, a positive lens, and a cemented lens made up of two negative lenses, arranged in order from the object side to the image side. The third lens group L3 consists of a positive lens, a cemented lens made up of a concave meniscus negative lens on the object side, and a concave meniscus positive lens on the object side, arranged in order from the object side to the image side. The fourth lens group L4 consists of a positive lens and a cemented lens made up of a positive lens and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side. The fifth lens group L5 consists of a negative lens, a positive lens, another negative lens, and a concave meniscus negative lens on the object side, arranged in order from the object side to the image side. The aperture diaphragm SP is positioned adjacent to the object side of the third lens group L3.

[0072] Figure 6 shows the aberration diagrams of the lens device of Example 3 at (a) infinity focus and (b) closest focus (magnification β = -1.0). All aberrations are well corrected. Table 1 shows the numerical values ​​in Example 3 corresponding to conditions (1) to (16). The lens device according to Example 3 satisfies conditions (1) to (16), is compact, yet enables magnified photography from infinity to 1:1 magnification, and possesses high optical performance. [Examples]

[0073] Figure 7 shows cross-sectional views of the lens device of Example 4 at (a) infinity focus and (b) closest focus (magnification β = -1.0). Figure 8 shows aberration diagrams of the lens device of Example 4 at (a) infinity focus and (b) closest focus (magnification β = -1.0). The lens device of Example 4 has an aperture ratio of approximately 3.6.

[0074] The lens device of Example 4 has, in order from the object side to the image side, a first lens group L1 having positive refractive power, a second lens group L2 having negative refractive power, a third lens group L3 having positive refractive power, a fourth lens group L4 having positive refractive power, and a fifth lens group L5 having negative refractive power. During focusing from infinity to close range, the second lens group L2 moves towards the image, and the fourth lens group L4 moves towards the object, each following a different trajectory. The first lens group L1 does not move during focusing.

[0075] The first lens group L1 consists of, in order from the object side to the image side, a positive lens, a positive lens, a cemented lens of a positive and a negative lens, and a meniscus positive lens that is convex towards the object side. The second lens group L2 consists of a negative lens, a cemented lens comprising a meniscus negative lens convex to the object side, and a meniscus positive lens convex to the object side, arranged in order from the object side to the image side. The third lens group L3 consists of a positive lens, a cemented lens made up of a concave meniscus negative lens on the object side, and a concave meniscus positive lens on the object side, arranged in order from the object side to the image side. The fourth lens group L4 consists of a cemented lens comprising a convex meniscus negative lens and a positive lens on the object side, arranged in order from the object side to the image side. The fifth lens group L5 consists of, in order from the object side to the image side, a convex meniscus negative lens, a positive lens, a negative lens on the object side, and a concave meniscus negative lens on the object side. The aperture diaphragm SP is positioned adjacent to the object side of the third lens group L3.

[0076] Figure 8 shows the aberration diagrams of the lens device of Example 4 at (a) infinity focus and (b) closest focus (magnification β = -1.0). All aberrations are well corrected. Table 1 shows the numerical values ​​in Example 4 corresponding to conditions (1) to (16). The lens device according to Example 4 satisfies conditions (1) to (16), is compact, yet enables magnified photography from infinity to 1:1 magnification, and possesses high optical performance.

[0077] As described above, by appropriately setting the configuration of each lens group according to each embodiment, a lens device can be obtained that is compact yet provides high optical performance from infinity focus to the closest focusing distance.

[0078] (Numerical examples) The following shows the numerical values ​​corresponding to Examples 1 to 4. In each numerical example, ri is the radius of curvature of the i-th plane counted from the object side, di is the lens thickness or air gap between the i-th plane and the (i+1)-th plane, and ndi and νdi are the refractive index and Abbe number of the optical element between the i-th plane and the (i+1)-th plane with respect to the d-line, respectively.

[0079] The asterisk (*) to the right of the surface number indicates that the surface is aspherical. The aspherical shape is defined as follows: with the X-axis in the direction of the optical axis, the H-axis perpendicular to the optical axis, and the direction of light propagation as positive; R being the paraaxial radius of curvature; K being the cone constant; and A4, A6, A8, A10, and A12 being the aspherical coefficients, respectively.

number

[0080] In numerical examples 1 to 4, BF represents the back focus, and the angle of view represents the half-angle of view calculated paraxially. The variable plane spacing values ​​are shown for the position where the focus is at infinity and the magnification is 1:1 (β = -1.0).

[0081] (Numerical Example 1) Unit: mm Surface data Face number rd nd vd 1 103.983 4.53 1.87070 40.7 2 -184.034 0.15 3 43.663 6.17 1.59282 68.6 4 -111.507 1.00 1.84666 23.8 5 24.819 2.00 6 27.248 4.63 1.95375 32.3 7 239.865 (variable) 8* -67.582 1.00 1.85135 40.1 9* 34.307 1.83 10 168.237 1.00 2.00100 29.1 11 31.785 3.70 1.95906 17.5 12 3779.617 (variable) 13 (aperture) ∞ 0.98 14 79.946 5.48 1.52841 76.5 15 -30.197 1.00 1.87070 40.7 16 -61.003 1.49 17 -248.944 2.74 1.90043 37.4 18 -51.456 (variable) 19 41.650 4.12 1.69680 55.5 20 -66.566 0.23 21 -55.727 1.00 1.95906 17.5 22 -133.795 (variable) 23 -335.955 0.99 1.49700 81.5 24 21.640 9.85 25 -27.920 4.78 1.57501 41.5 26 -16.627 0.77 27 -15.890 1.50 2.05090 26.9 28 -79.195 0.68 29 -549.909 7.97 1.66680 33.0 30 -27.242 10.00 Image plane ∞ Aspherical data Side 8 K = 0.00000e+00 A 4= 1.31836e-05 A 6=-1.36454e-07 A 8= 1.03998e-09 A10=-4.48037e-12 A12= 8.10808e-15 9th page K = 0.00000e+00 A 4= 8.31737e-06 A 6=-1.27231e-07 A 8= 8.92540e-10 A10=-3.61625e-12 A12= 6.33924e-15 Various data Focal length 87.89 F-number 2.88 Half-angle 13.83 Image height 21.64 Lens length: 119.15 BF 10.00 Focus position Infinity β=-1.0 d 7 3.18 19.51 d12 18.33 1.99 d18 16.04 1.99 d22 1.99 16.00 Lens group data Group starting plane focal length 1 1 45.08 2 8 -30.38 3 13 43.96 4 19 58.27 5 23 -32.78 (Numerical Example 2) Unit: mm Surface data Face number rd nd vd 1 97.467 4.53 1.87070 40.7 2 -195.208 0.15 3 42.094 6.36 1.61800 63.4 4 -95.780 1.00 1.92119 24.0 5 24.777 1.73 6 26.932 4.87 1.95375 32.3 7 724.484 (variable) 8* -62.361 1.00 1.85135 40.1 9* 32.346 1.59 10 91.407 1.00 2.05090 26.9 11 27.293 3.90 1.95906 17.5 12 514.495 (variable) 13 (aperture) ∞ 1.39 14 95.300 4.95 1.65844 50.9 15 -31.981 1.00 2.00100 29.1 16 -73.646 1.49 17 -65.307 2.27 1.89286 20.4 18 -39.989 (variable) 19 56.449 2.98 1.72916 54.7 20 -805.813 0.04 21 109.269 4.11 1.56732 42.8 22 -39.994 1.00 1.95906 17.5 23 -98.885 (variable) 24 -393.591 0.99 1.72916 54.7 25 24.393 2.76 26 26.435 7.67 1.59551 39.2 27 -36.586 0.50 28 -57.076 1.50 2.05090 26.9 29 80.816 6.47 30 -20.180 1.50 1.72916 54.7 31 -39.649 14.22 Image plane ∞ Aspherical data Side 8 K = 0.00000e+00 A 4= 1.18759e-05 A 6=-7.30033e-08 A 8= 3.86835e-10 A10=-1.35436e-12 A12= 2.47967e-15 9th page K = 0.00000e+00 A 4= 4.69570e-06 A 6=-5.74538e-08 A 8= 1.92993e-10 A10=-3.64909e-13 A12= 8.48019e-16 Various data Focal length 87.15 F-number 2.88 Half-angle 13.94 Image height 21.64 Lens length: 119.29 BF 14.22 Focus position Infinity β=-1.0 d 7 3.03 18.19 d12 17.26 2.09 d18 16.06 1.99 d23 2.00 16.02 Lens group data Group starting plane focal length 1 1 43.99 2 8 -29.73 3 13 54.90 4 19 53.37 5 24 -21.84 (Numerical Example 3) Unit: mm Surface data Face number rd nd vd 1 109.854 5.22 1.83481 42.7 2 -236.046 0.20 3 57.174 7.51 1.72916 54.7 4 -166.228 1.60 1.92119 24.0 5 30.853 2.03 6 32.384 6.98 1.78880 28.4 7 269.875 (variable) 8* -123.132 1.50 1.85135 40.1 9* 47.257 0.91 10 63.035 5.21 1.95906 17.5 11 -107.156 1.50 1.90110 27.1 12 67.626 (variable) 13 (aperture) ∞ 1.79 14 128.269 6.10 1.55200 70.7 15 -43.608 1.40 1.90043 37.4 16 -84.869 1.58 17 -95.612 2.55 2.05090 26.9 18 -60.698 (variable) 19 51.383 4.14 1.49700 81.5 20 -161.660 0.05 21 201.195 3.97 1.48749 70.2 22 -51.251 1.40 2.05090 26.9 23 -106.004 (variable) 24 -315.430 1.20 1.69680 55.5 25 30.445 15.20 26 72.961 7.01 1.85478 24.8 27 -48.701 0.50 28 -59.601 1.50 1.95906 17.5 29 310.340 4.49 30 -43.864 1.70 1.51633 64.1 31 -750.000 19.55 Image plane ∞ Aspherical data Side 8 K = 0.00000e+00 A 4=-1.73213e-06 A 6= 1.25288e-08 A 8=-5.19847e-11 A10= 9.72487e-14 A12=-5.09355e-17 9th page K = 0.00000e+00 A 4=-2.96560e-06 A 6= 1.25389e-08 A 8=-5.16581e-11 A10= 7.87152e-14 A12= 2.45418e-18 Various data Focal length 130.02 F-number 2.88 Half-angle 9.45 Image height 21.64 Lens length: 160.82 BF 19.55 Focus position Infinity β=-1.0 d 7 3.80 25.12 d12 25.17 3.86 d18 23.05 1.99 d23 2.00 23.01 Lens group data Group starting plane focal length 1 1 63.97 2 8 -43.59 3 13 76.04 4 19 71.52 5 24 -36.63 (Numerical Example 4) Unit: mm Surface data Face number rd nd vd 1 134.630 4.88 1.48749 70.2 2 -389.191 0.30 3 67.287 6.30 1.49700 81.6 4 -1742.493 0.30 5 52.818 8.30 1.49700 81.6 6 -316.928 2.00 1.63930 44.9 7 36.742 1.34 8 45.751 4.50 1.48749 70.2 9 96.570 (Variable) 10* -3240.956 1.70 1.85135 40.1 11* 55.187 1.07 12 96.726 1.60 1.69680 55.5 13 38.783 3.18 1.92286 20.9 14 67.248 (variable) 15 (aperture) ∞ 2.10 16 250.674 4.29 1.74950 35.3 17 -52.205 1.50 1.92119 24.0 18 -141.305 2.30 19 -82.174 1.83 2.00100 29.1 20 -74.664 (variable) 21 39.213 1.50 1.95375 32.3 22 26.768 6.06 1.59282 68.6 23 -244.081 (variable) 24 128.599 1.50 1.72916 54.7 25 28.352 22.12 26 76.276 8.61 1.60342 38.0 27 -39.606 0.50 28 -47.291 1.80 1.48749 70.2 29 183.056 5.51 30 -42.328 1.80 1.48749 70.2 31 -198.044 20.35 Image plane ∞ Aspherical data Side 10 K = 0.00000e+00 A 4=-7.37263e-06 A 6= 3.20696e-08 A 8=-1.09146e-10 A10= 2.25548e-13 A12=-2.03478e-16 Page 11 K = 0.00000e+00 A 4=-7.83337e-06 A 6= 3.20915e-08 A 8=-1.11248e-10 A10= 2.34738e-13 A12=-2.18317e-16 Various data Focal length 174.62 F-number 3.60 Half-angle 7.06 Image height 21.64 Lens length: 188.69 BF 20.35 Focus position Infinity β=-1.0 d 9 5.50 33.81 d14 32.08 3.77 d20 31.41 2.50 d23 2.50 31.37 Lens group data Group starting plane focal length 1 1 85.52 2 10 -60.56 3 15 133.92 4 21 74.78 5 24 -53.54 Table 1 shows the values ​​for Examples 1 to 4 corresponding to conditional expressions (1) to (16).

[0082] [Table 1]

[0083] (Imaging device) Next, an embodiment of a digital still camera using the lens device of this disclosure as the imaging optical system will be described with reference to Figure 9. In Figure 9, 10 is the camera body, and 11 is the imaging optical system composed of one of the lens devices described in Examples 1 to 4. 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 subject image formed by the imaging optical system 11. The camera body 10 may be a so-called single-lens reflex camera with a quick-return mirror, or a so-called mirrorless camera without a quick-return mirror. By applying the lens device of this disclosure to an imaging device such as a digital still camera, it is possible to obtain an imaging device with high optical performance that is small in size, capable of shooting at infinity and magnified shooting at 1:1 magnification.

[0084] This disclosure includes the following components: (Composition 1) A lens device having, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the spacing between adjacent lens groups changes during focusing. During focusing, the first lens group does not move, while the second and fourth lens groups move. When the total focal length of the entire system is f, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.44 <f3 / f<0.8 0 <f4 / f<0.72 A lens device characterized by satisfying the following conditions. (Configuration 2) When the focal length of the fifth lens group is f5, -0.50 <f5 / f<-0.15 The lens device according to configuration 1, characterized in that it satisfies the following conditions. (Composition 3) When the focal length of the fifth lens group is f5, -0.85 <f5 / f3<-0.30 A lens device according to configuration 1 or 2, characterized in that it satisfies the following conditions. (Composition 4) When the focal length of the fifth lens group is f5, -0.80 <f5 / f4<-0.30 A lens device according to any one of configurations 1 to 3, characterized in that it satisfies the following conditions. (Composition 5) 0.65 <f3 / f4<2.00 A lens device according to any one of configurations 1 to 4, characterized in that it satisfies the following conditions. (Composition 6) When the focal length of the second lens group is f2, -0.80 <f2 / f3<-0.35 A lens device according to any one of configurations 1 to 5, characterized in that it satisfies the following conditions. (Composition 7) When the combined focal length of the first lens group and the second lens group at infinity focus is f12, 0 <f / |f12|<0.30 A lens device according to any one of configurations 1 to 6, characterized in that it satisfies the following conditions. (Composition 8) When the focal length of the lens element G3A closest to the object in the third lens group is f3A, and the focal lengths of all the lens elements G3B closer to the image than lens element G3A in the third lens group are f3B, 0.40 <f3B / f3A<5.00 A lens device according to any one of configurations 1 to 7, characterized in that it satisfies the following conditions. (Composition 9) When the focal length of the fifth lens group is f5, and the focal length of the lens element G5A closest to the object in the fifth lens group is f5A, 0.80 <f5A / f5<1.60 A lens device according to any one of configurations 1 to 8, characterized in that it satisfies the following conditions. (Composition 10) When the back focus at infinity is sk and the total optical length of the entire system is TL, 6.0 <sk / TL<14.0 A lens device according to any one of configurations 1 to 9, characterized in that it satisfies the following conditions. (Composition 11) When the distance the second lens group moves along the optical axis when focusing from infinity to closest focus is MD2, and the total optical length of the entire system is TL, 0.90 <MD2 / TL<1.80 A lens device according to any one of configurations 1 to 10, characterized in that it satisfies the following conditions. (Composition 12) When the distance the fourth lens group moves along the optical axis when focusing from infinity to closest focus is MD4, and the total optical length of the entire system is TL, 0.80 <MD4 / TL<1.60 A lens device according to any one of configurations 1 to 11, characterized by satisfying the following conditions. (Composition 13) When the focus sensitivity of the second lens group at infinity focus is ES2, -5.00 <ES2<-3.00 A lens device according to any one of configurations 1 to 12, characterized in that it satisfies the following conditions. (Composition 14) When the focus sensitivity of the fourth lens group at infinity focus is set to ES4, 2.00 <ES4<3.50 A lens device according to any one of configurations 1 to 13, characterized in that it satisfies the following conditions. (Composition 15) When the shape factor of the lens element G5A closest to the object in the fifth lens group is G5ASF, 0.70 <G5ASF<2.00 A lens device according to any one of configurations 1 to 14, characterized in that it satisfies the following conditions. (Composition 16) A lens device according to any one of configurations 1 to 15, characterized in that when focusing from infinity to a close distance, the second lens group moves toward the image side and the fourth lens group moves toward the object side along different trajectories. (Composition 17) A lens device having, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the spacing between adjacent lens groups changes during focusing. A lens device characterized in that, during focusing, the first lens group does not move, while the second lens group and the fourth lens group move. (Composition 18) An imaging device characterized by having a lens device as described in any of configurations 1 to 17, and an image sensor that receives an image formed by the lens device. [Explanation of symbols]

[0085] L1 First lens group L2 Second lens group L3 Third lens group L4 4th lens group L5 5th lens group

Claims

1. A lens device having, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the spacing between adjacent lens groups changes during focusing. During focusing, the first lens group does not move, while the second and fourth lens groups move. When the total focal length of the entire system is f, the focal length of the third lens group is f3, and the focal length of the fourth lens group is f4, 0.44<f3 / f<0.8 0<f4 / f<0.72 A lens device characterized by satisfying the following conditions.

2. When the focal length of the fifth lens group is f5, -0.50<f5 / f<-0.15 The lens device according to claim 1, characterized in that it satisfies the following conditions.

3. When the focal length of the fifth lens group is f5, -0.85<f5 / f3<-0.30 The lens device according to claim 1, characterized in that it satisfies the following conditions.

4. When the focal length of the fifth lens group is f5, -0.80<f5 / f4<-0.30 The lens device according to claim 1, characterized in that it satisfies the following conditions.

5. 0.65<f3 / f4<2.00 The lens device according to claim 1, characterized in that it satisfies the following conditions.

6. When the focal length of the second lens group is f2, -0.80<f2 / f3<-0.35 The lens device according to claim 1, characterized in that it satisfies the following conditions.

7. When the combined focal length of the first lens group and the second lens group at infinity focus is f12, 0<f / |f12|<0.30 The lens device according to claim 1, characterized in that it satisfies the following conditions.

8. When the focal length of the lens element G3A closest to the object in the third lens group is f3A, and the focal lengths of all the lens elements G3B closer to the image than lens element G3A in the third lens group are f3B, 0.40<f3B / f3A<5.00 The lens device according to claim 1, characterized in that it satisfies the following conditions.

9. When the focal length of the fifth lens group is f5, and the focal length of the lens element G5A closest to the object in the fifth lens group is f5A, 0.80<f5A / f5<1.60 The lens device according to claim 1, characterized in that it satisfies the following conditions.

10. When the back focus at infinity is sk and the total optical length of the system is TL, 6.0<sk / TL<14.0 The lens device according to claim 1, characterized in that it satisfies the following conditions.

11. When the distance the second lens group moves along the optical axis when focusing from infinity to closest focus is MD2, and the total optical length of the entire system is TL, 0.90<MD2 / TL<1.80 The lens device according to claim 1, characterized in that it satisfies the following conditions.

12. When the distance the fourth lens group moves along the optical axis when focusing from infinity to closest focus is MD4, and the total optical length of the entire system is TL, 0.80<MD4 / TL<1.60 The lens device according to claim 1, characterized in that it satisfies the following conditions.

13. When the focus sensitivity of the second lens group at infinity focus is ES2, -5.00<ES2<-3.00 The lens device according to claim 1, characterized in that it satisfies the following conditions.

14. When the focus sensitivity of the fourth lens group at infinity focus is ES4, 2.00<ES4<3.50 The lens device according to claim 1, characterized in that it satisfies the following conditions.

15. When the shape factor of the lens element G5A closest to the object in the fifth lens group is G5ASF, 0.70<G5ASF<2.00 The lens device according to claim 1, characterized in that it satisfies the following conditions.

16. The lens device according to claim 1, characterized in that when focusing from infinity to a close distance, the second lens group moves toward the image side and the fourth lens group moves toward the object side along different trajectories.

17. A lens device having, in order from the object side to the image side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group with negative refractive power, wherein the spacing between adjacent lens groups changes during focusing. A lens device characterized in that, during focusing, the first lens group does not move, while the second lens group and the fourth lens group move.

18. An imaging device characterized by having a lens device according to any one of claims 1 to 17, and an image sensor that receives an image formed by the lens device.

Images