Large aperture zoom lens

Abstract

To provide a large diameter zoom lens including a standard region in a zooming region, small in open F value and compact in full length and capable of controlling autofocus at high speed.SOLUTION: The large diameter zoom lens consists of a first positive lens group, a second negative lens group, a third positive lens group, a fourth positive lens group, a fifth negative lens group, and a rear side lens group including one or more lens groups in order from the side of an object; the fifth lens group consists of a focus lens LF of a negative meniscus lens facing a convex surface on the side of the object moving to the side of an image surface when focused to a short distance object from an infinite distance object; and a zoom from a wide angle end to a telephoto end increases an interval between the first lens group and the second lens group, decreases an interval between the second lens group and the third lens group, decreases an interval between the third lens group and the fourth lens group, changes an interval between the fourth lens group and the fifth lens group, increases an interval between the fifth lens group and the rear side lens group, and satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a large-aperture zoom lens, and more particularly to a large-aperture zoom lens that includes a standard range in its magnification range, has a small maximum F-number, a compact overall length, and is capable of high-speed autofocus control. [Background technology]

[0002] Conventionally, in large-aperture zoom lenses with a small maximum aperture, it has been required that various aberrations be well corrected throughout the entire zoom range in order to obtain high imaging performance, that the entire optical system be compact, and that the focus lens group be lightweight in order to enable high-speed autofocus control.

[0003] For example, Patent Document 1 discloses a zoom lens having a relatively long back focus, which is composed of, 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, and a fourth lens group with positive refractive power.

[0004] Furthermore, Patent Document 2 discloses a zoom lens having a relatively long back focus, the zoom lens comprising, 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 negative refractive power, and a fifth lens group with positive refractive power, or the first lens group with positive refractive power, the second lens group with negative refractive power, the third lens group with positive refractive power, and a fourth lens group with positive refractive power. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-128361 A [Patent Document 2] JP 2012-123156 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the zoom lenses disclosed in the above-mentioned patent documents have the following problems.

[0007] In the conventional zoom lens disclosed in Patent Document 1, the focus lens group is composed of a large number of lenses and is heavy, so reducing the weight of the focus lens group is insufficient to enable high-speed autofocus control.

[0008] Furthermore, if the zoom lens disclosed in Patent Document 1 is applied to a camera equipped with a so-called full-size image sensor with an image height equivalent to 21.63 mm, the back focus will become longer and the overall length will become longer as the overall optical system becomes larger. Therefore, it is particularly unsuitable for application to a mirrorless camera that is not equipped with a mirror for reflecting an image to an optical viewfinder and has a compact and lightweight camera system as a whole.

[0009] In the conventional zoom lens disclosed in Patent Document 2, similar to the zoom lens disclosed in Patent Document 1, the weight of the focus lens group is insufficient.

[0010] In addition, although it can be applied to a single-lens reflex camera equipped with a full-size image sensor, it is not suitable for use in a mirrorless camera due to its relatively long back focus and long overall length.

[0011] The present invention has been made in consideration of the above-mentioned problems with the conventional examples, and has an object to provide a large-aperture zoom lens that includes a standard range in its magnification range, has a small maximum F-number, is compact in overall length, and is capable of high-speed autofocus control. [Means for solving the problem]

[0012] In order to achieve the above object, a large-aperture zoom lens embodying the present invention includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a rear lens group G6 having a negative refractive power including one or more lens groups. side The fifth lens group G5 is a focusing lens LF made of a negative meniscus lens with a convex surface facing the object side that moves toward the image surface side when focusing from an object at infinity to an object at a close distance, and when zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the rear lens group G6 increases. side The spacing of the lens group GR is increased and is characterized by satisfying the following condition: (1) -3.0 <f5 / f4<-1.0 Where: f4: Focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

[0013] In addition, a large aperture zoom lens embodying the present invention is preferably characterized in that, during zooming from the wide-angle end to the telephoto end, the lens in the rear lens group GR located closest to the image plane is fixed with respect to the image plane.

[0014] In addition, in a large-aperture zoom lens embodying the present invention, it is preferable that the third lens group G3 and the fourth lens group G4 move toward the object side when changing magnification from the wide-angle end to the telephoto end, and that the following conditional expression is satisfied: (2) 1.0 <f3 / f4<5.0 Where: f3: Focal length of the third lens group G3 f4: Focal length of the fourth lens group G4

[0015] In addition, a large aperture zoom lens embodying the present invention is preferably characterized in that, when varying magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side and satisfies the following conditional expression: (3) -10.0 <f1 / f2<-3.0 Where: f1: focal length of the first lens group G1 f2: focal length of the second lens group G2

[0016] In addition, in a large-aperture zoom lens embodying the present invention, the first lens group G1 preferably consists of, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a positive lens L12 having a convex surface facing the object side, and a positive lens L13 having a convex surface facing the object side, and is characterized in that it satisfies the following conditional expression: (4) νd1n<30.0 (5) 65.0<νd1p (6) 3.0<νd1p / νd1n Where: νd1n: ​​Abbe number of the negative meniscus lens L11 νd1p: Abbe number of the positive lens having the lowest dispersion among the positive lens L12 and the positive lens L13

[0017] In addition, a large-aperture zoom lens embodying the present invention is preferably characterized in that the fourth lens group G4 consists of, in order from the object side, a lens group G41 which has at least one positive lens and has positive refractive power as a whole, and a positive lens G42 which has an aspheric surface, and which satisfies the following conditional expression: (7) 0.3 <f41 / f42<0.6 Where: f41: focal length of lens group G41 f42: focal length of positive lens G42

[0018] A large aperture zoom lens embodying the present invention is preferably characterized in that it satisfies the following conditional expression: (8) -0.3<1 / fRW<0.0 Where: fRW: focal length of the rear lens group GR at the wide-angle end [mm]

[0019] In addition, in a large-aperture zoom lens embodying the present invention, the rear lens group GR is preferably composed of one lens group, the rear lens group GR being composed of, in order from the object side, a lens unit RF1 having positive refractive power and a lens unit RR1 having negative refractive power, the lens unit RF1 having at least a positive lens with a convex surface facing the object side, the lens unit RR1 having at least one negative lens closest to the image side, and being characterized in that the following conditional expression is satisfied: (9) -2.0 <fRF1 / fRR1<0.0 Where: fRF1: focal length of lens unit RF1 fRR1: focal length of lens unit RR1

[0020] In addition, in a large-aperture zoom lens embodying the present invention, the rear lens group GR preferably consists of two lens groups, and the distance between the two lens groups increases when changing magnification from the wide-angle end to the telephoto end.

[0021] In addition, in a large-aperture zoom lens embodying the present invention, the two lens groups of the rear lens group GR are preferably, in order from the object side, a lens group RF2 having positive refractive power and a lens group RR2 having negative refractive power, the lens group RF2 having at least a positive lens with a convex surface facing the object side, and the lens group RR2 having at least one negative lens, the lens group RR2 having at least one negative lens, the lens group GR being characterized in that it satisfies the following conditional formula: (10) -2.0 <fRF2 / fRR2<0.0 (11) 0.5 <RWD / RTD<1.0 Where: fRF2: focal length of lens group RF2 fRR2: focal length of lens group RR2 RWD: composite thickness on the optical axis of the rear lens group GR at the wide-angle end RTD: composite thickness on the optical axis of the rear lens group GR at the telephoto end Effect of the Invention

[0022] According to a large-aperture zoom lens embodying the present invention, it is possible to obtain a large-aperture zoom lens that includes a standard range in its magnification range, has a small maximum F-number, is compact in overall length, and is capable of high-speed autofocus control. [Brief description of the drawings]

[0023] [Figure 1] 1 is a lens configuration diagram of a large-aperture zoom lens according to a first embodiment of the present invention. [Diagram 2] 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at the wide-angle end when focused on infinity. [Diagram 3] 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at an intermediate focal length and focused on infinity. [Figure 4] 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at the telephoto end when focused on infinity. [Diagram 5] 4A to 4C are lateral aberration diagrams of the large-aperture zoom lens of Example 1 at the wide-angle end when focused on infinity. [Figure 6] 4A to 4C are diagrams illustrating lateral aberration of the large-aperture zoom lens of Example 1 at an intermediate focal length and focused on infinity. [Figure 7] 4A to 4C are lateral aberration diagrams of the large-aperture zoom lens of Example 1 at the telephoto end when focused on infinity. [Figure 8] FIG. 4 is a lens configuration diagram of a large-aperture zoom lens according to a second embodiment of the present invention. [Figure 9] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 at the wide-angle end when focused on infinity. [Figure 10] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 when the lens is at an intermediate focal length and focused on an object at infinity. [Figure 11] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 at the telephoto end when focused on infinity. [Figure 12] 6A to 6C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 at the wide-angle end when focused on infinity. [Figure 13] 6A to 6C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 when the lens is at an intermediate focal length and focused on an object at infinity. [Figure 14]6A to 6C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 at the telephoto end when focused on infinity. [Figure 15] FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a third embodiment of the present invention. [Figure 16] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 at the wide-angle end when focused on an object at infinity. [Figure 17] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 when the lens is at an intermediate focal length and focused on an object at infinity. [Figure 18] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 at the telephoto end when focused on infinity. [Figure 19] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 at the wide-angle end when focused on infinity. [Figure 20] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 when the lens is at an intermediate focal length and focused on an object at infinity. [Figure 21] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 at the telephoto end when focused on infinity. [Figure 22] FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a fourth embodiment of the present invention. [Diagram 23] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 at the wide-angle end and focused on an object at infinity. [Figure 24] 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 at an intermediate focal length and focused on infinity. [Diagram 25] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 at the telephoto end when focused on an object at infinity. [Figure 26] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at the wide-angle end and focused on infinity. [Figure 27] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at an intermediate focal length and focused on infinity. [Figure 28] 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at the telephoto end when focused on infinity. [Figure 29] FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a fifth embodiment of the present invention. [Diagram 30] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 at the wide-angle end when focused on infinity. [Diagram 31] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 when the lens is at an intermediate focal length and focused on an object at infinity. [Diagram 32] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 at the telephoto end when focused on infinity. [Diagram 33] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 at the wide-angle end when focused on infinity. [Diagram 34] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 when the lens is at an intermediate focal length and focused on an object at infinity. [Diagram 35] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 at the telephoto end when focused on infinity. [Diagram 36] FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a sixth embodiment of the present invention. [Figure 37] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 at the wide-angle end when focused on an object at infinity. [Figure 38] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 when the lens is at an intermediate focal length and focused on an object at infinity. [Figure 39] 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 at the telephoto end when focused on an object at infinity. [Diagram 40] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 at the wide-angle end when focused on infinity. [Diagram 41] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 when the lens is at an intermediate focal length and focused on an object at infinity. [Diagram 42] 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 at the telephoto end when focused on infinity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A large aperture zoom lens according to an embodiment of the present invention will now be described in detail with reference to the drawings. In the present invention, a lens unit refers to a single lens or a cemented lens that as a whole constitutes one optical element.

[0025] 1, 8, 15, 22, 29, and 36 are lens configuration diagrams of the large-aperture zoom lens of this embodiment. As shown in each lens configuration diagram, the large-aperture zoom lens of this embodiment is composed of, in order from the object side, a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, a fifth lens group G5 with negative refractive power, and a rear lens group GR with negative refractive power. The rear lens group GR is composed of one or more lens groups, and a positive lens unit with a convex surface facing the object side is arranged closest to the object side, and a negative lens unit is arranged as the lens closest to the image side.

[0026] In the large-aperture zoom lens of this embodiment, when the magnification is changed from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image plane, the third lens group G3 moves toward the object side, the fourth lens group moves toward the object side, and the fifth lens group moves toward the object side. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the rear lens group GR increases.

[0027] In addition, when the rear lens group GR consists of one lens group, the rear lens group GR is fixed with respect to the image plane, and when the rear lens group GR consists of two lens groups, the front lens group of the rear lens group GR moves toward the object side and the rear lens group is fixed with respect to the image plane, and the distance between the front lens group and the rear lens group increases.

[0028] The fifth lens group G5 is composed of a focusing lens LF made of a negative meniscus lens with a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to a close object.

[0029] In the large aperture zoom lens of this embodiment, the main effect of zooming is achieved by increasing the distance between the first lens group G1 with positive refractive power and the second lens group G2 with negative refractive power when zooming from the wide-angle end to the telephoto end. Here, in order to reduce the amount of movement of the first lens group G1 when zooming, it is preferable that the refractive power arrangement be an inverted telephoto type at the wide-angle end and a telephoto type at the telephoto end. With this configuration, it is possible to reduce the amount of movement of the first lens group G1 while shortening the overall length of the optical system at the wide-angle end.

[0030] Therefore, at the wide-angle end, the first lens group G1, which has positive refractive power, and the second lens group G2, which has negative refractive power, are arranged close to each other so that their composite refractive power is negative, and a third lens group G3, which has positive refractive power overall, is arranged at a position away from the composite system of the first lens group G1 and the second lens group G2 toward the image side, a fourth lens group G4, which has positive refractive power, is arranged at a position further away toward the image side, a fifth lens group G5, which has negative refractive power, is arranged behind the fourth lens group, and a rear lens group GR is arranged behind that.

[0031] On the other hand, at the telephoto end, the second lens group G2 with negative refractive power, the third lens group G3 with positive refractive power, the fourth lens group G4 with positive refractive power, and the fifth lens group G5 with negative refractive power are arranged close to each other so that the composite refractive power behind the first lens group G1 is negative, and in relation to the first lens group G1 with positive refractive power, a telephoto-type refractive power arrangement is formed as a whole, making it possible to shorten the overall length of the optical system at the telephoto end.

[0032] In the large-aperture zoom lens of this embodiment, the fifth lens group G5 is adjacent to the fourth lens group, and has a floating effect for appropriately adjusting the curvature of field by moving to an arbitrary position relative to the fourth lens group G4 during zooming, and is a focusing lens LF made of a negative meniscus lens with a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to a close object. The following conditional expression (1) is satisfied. (1) -3.0 <f5 / f4<-1.0 Where: f4: Focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

[0033] In order to move a lightweight lens and enable high-speed autofocus control, it is preferable to make the focusing lens LF small. In order to make the focusing lens LF small, it is important to make its effective diameter as small as possible. However, if the focusing lens LF is arranged in the final lens group closest to the image plane in order to make the effective diameter of the focusing lens LF small, it becomes difficult to arrange an electrical board for communication with the camera body arranged around the mount, and if the arrangement of the electrical board is prioritized, the effective diameter of the focusing lens LF is excessively restricted, which is not preferable.

[0034] In this embodiment, the fifth lens group G5 is disposed adjacent to the fourth lens group G4, and when changing magnification from the wide-angle end to the telephoto end, the fifth lens group G5 and the rear lens group G4 are disposed adjacent to each other. side The spacing between the lens groups GR is increased. This makes it possible to ensure sufficient movement space on the image surface side of the focusing lens LF, which moves a large amount at the telephoto end when focusing from an object at infinity to an object at a close distance. Furthermore, in this embodiment, by arranging the fourth lens group G4 adjacent to the image surface side, it is possible to more easily ensure movement space on the image surface side of the focusing lens LF. Also, in this embodiment, the focusing lens LF is a negative meniscus lens with a convex surface facing the object side, making it possible to suppress aberration fluctuations during focusing.

[0035] Conditional formula (1) defines the ratio of the focal length of the fourth lens group G4 to the focal length of the fifth lens group G5.

[0036] If the upper limit of conditional expression (1) is exceeded and the negative refractive power of the fifth lens group G5 becomes large, the decentering sensitivity of the focusing lens LF increases, and there is a risk of the optical performance deteriorating depending on the focusing position.

[0037] If the lower limit of conditional expression (1) is exceeded and the negative refractive power of the fifth lens group G5 becomes small, the amount of movement of the focusing lens LF increases when focusing on a close-up object, making it difficult to achieve high-speed autofocus control.

[0038] By limiting the lower limit of the above-mentioned conditional expression (1) to −2.2 and the upper limit to −1.6, the above-mentioned effect can be ensured.

[0039] In the large aperture zoom lens of this embodiment, when changing magnification from the wide-angle end to the telephoto end, the lens closest to the image plane in the rear lens group GR is fixed with respect to the image plane. This eliminates the need to add a movable mechanism or the like to the lens closest to the image plane, making it easy to increase the outer diameter of the lens closest to the image plane in accordance with the camera body mount specifications, and sufficiently suppresses the exit angle of the light beam that forms an image on the periphery of the image sensor.

[0040] In the large aperture zoom lens of this embodiment, the third lens group G3 and the fourth lens group G4 move toward the object side during zooming from the wide-angle end to the telephoto end. (2) 1.0 <f3 / f4<5.0 Where: f3: Focal length of the third lens group G3 f4: Focal length of the fourth lens group G4

[0041] By appropriately moving the third lens group G3 and the fourth lens group G4 toward the object side when changing magnification from the wide-angle end to the telephoto end, the distance between the third lens group G3 and the fourth lens group G4 can be appropriately reduced, thereby suppressing the curvature of field that changes when changing magnification.

[0042] If the lower limit of conditional expression (2) is exceeded and the refractive power of the third lens group G3 becomes large, then when the lens spacing between the third lens group G3 and the fourth lens group G4 is changed during zooming to suppress curvature of field, the spherical aberration fluctuation increases in the intermediate zoom range due to the influence of the spherical aberration generated in the third lens group G3.

[0043] If the upper limit of conditional expression (2) is exceeded and the refractive power of the third lens group G3 becomes small, the outer diameter of the fourth lens group G4 becomes large and the refractive power of the fourth lens group G4 becomes too large, which increases the sensitivity to spherical aberration in the fourth lens group G4 and further increases the sensitivity to decentering, making it difficult to suppress manufacturing variations, which may adversely affect productivity.

[0044] By limiting the lower limit of the above-mentioned conditional expression (2) to 2.1 and the upper limit to 3.4, the above-mentioned effect can be ensured.

[0045] In the large aperture zoom lens of this embodiment, the first lens group G1 moves toward the object side during zooming from the wide-angle end to the telephoto end. (3) -10.0 <f1 / f2<-3.0 Where: f1: focal length of the first lens group G1 f2: focal length of the second lens group G2

[0046] If the refractive power of the first lens group G1 becomes too large to satisfy the lower limit of condition (3), it becomes difficult to correct spherical aberration and lateral chromatic aberration at the telephoto end, making it impossible to obtain sufficient optical performance. Also, if the refractive power of the second lens group G2 becomes too small, the overall lens length at the wide-angle end becomes too large.

[0047] If the upper limit of conditional expression (3) is exceeded and the refractive power of the first lens group G1 becomes small, the amount of movement of the first lens group G1 during zooming becomes too large. Also, if the refractive power of the second lens group G2 becomes large, it becomes difficult to correct aberrations on the wide-angle end side, making it impossible to obtain sufficient optical performance in the peripheral area.

[0048] By limiting the lower limit of the above-mentioned conditional expression (3) to −6.4 and the upper limit to −4.6, the above-mentioned effect can be ensured.

[0049] In the large-aperture zoom lens of this embodiment, the first lens group G1 is composed of, in order from the object side, a negative meniscus lens L11 with a convex surface facing the object side, a positive lens L12 with a convex surface facing the object side, and a positive lens L13 with a convex surface facing the object side, and satisfies the following conditional expressions (4) to (6). (4) νd1n<30.0 (5) 65.0<νd1p (6) 3.0<νd1p / νd1n Where: νd1n: ​​Abbe number of the negative meniscus lens L11 νd1p: Abbe number of the positive lens having the lowest dispersion among the positive lens L12 and the positive lens L13

[0050] In the first lens group G1 having positive refractive power, by decreasing the Abbe number of the negative lens constituting it and increasing the Abbe number of the positive lens, it is possible to reduce the curvature of the negative lens and the positive lens at the wide-angle end where the angle of view is large, and the entire first lens group G1 can be made thinner. Furthermore, by selecting a glass type with low dispersion and high anomalous dispersion for the positive lens of the first lens group G1, it is possible to effectively correct the axial chromatic aberration and lateral chromatic aberration at the telephoto end.

[0051] When the upper limit of conditional expression (4) is exceeded and the Abbe number of the negative meniscus lens L11 becomes large, it becomes impossible to select a lightweight glass material having a high refractive index.

[0052] If the lower limit of conditional expression (5) is exceeded and the Abbe number of the positive lens having the lowest dispersion among the positive lenses L12 and L13 becomes small, a high-dispersion glass material will be selected for the positive lens, making it difficult to correct axial chromatic aberration and lateral chromatic aberration and also making it impossible to select a lightweight glass material.

[0053] If the lower limit of conditional formula (6) is exceeded and the Abbe number of the positive lens having the lowest dispersion among the positive lens L12 and the positive lens L13 becomes small, or the Abbe number of the negative meniscus lens L11 becomes large, the positive lens becomes high dispersion, or the negative meniscus lens L11 becomes low dispersion, and the difference in Abbe number between the positive lens and the negative meniscus lens L11 becomes small, making it difficult to sufficiently thin the first lens group G1. This leads to an increase in the overall lens length, an increase in the filter diameter, and an increase in the lens weight, making it impossible to achieve a sufficiently small and lightweight design.

[0054] Regarding the above-mentioned conditional expression (4), by limiting its lower limit to 15.0 and its upper limit to 22.0, the above-mentioned effect can be ensured more reliably.

[0055] Regarding the above-mentioned conditional expression (5), by limiting its lower limit to 70.0 and its upper limit to 96.0, the above-mentioned effect can be ensured more reliably.

[0056] Regarding the above-mentioned conditional expression (6), by restricting its lower limit to 3.8 and its upper limit to 4.7, the above-mentioned effect can be ensured more reliably.

[0057] In the large-aperture zoom lens of this embodiment, the fourth lens group G4 is composed of, in order from the object side, a lens group G41 having at least one positive lens and positive refractive power as a whole, and a positive lens G42 having an aspheric surface, and satisfies the following conditional expression (7). (7) 0.3 <f41 / f42<0.6 Where: f41: focal length of lens group G41 f42: focal length of positive lens G42

[0058] If the lower limit of conditional expression (7) is exceeded and the refractive power of the lens group G41 becomes large, the sensitivity to relative shift between the lens group G41 and the positive lens G42 increases, and the deterioration of optical performance due to manufacturing errors increases, which may have an adverse effect on productivity.

[0059] If the upper limit value of conditional expression (7) is exceeded and the refractive power of the positive lens G42 becomes large, the sensitivity of the positive lens G42, which is an aspheric lens, to inter-surface shift decentering error increases, making it difficult to suppress manufacturing variations, which may have an adverse effect on productivity.

[0060] By limiting the lower limit of the above-mentioned conditional expression (7) to 0.39 and the upper limit to 0.46, the above-mentioned effect can be ensured.

[0061] In the large-aperture zoom lens of this embodiment, the rear lens unit GR having negative refractive power satisfies the following conditional expression (8). (8) -0.3<1 / fRW<0.0 Where: fRW: focal length of the rear lens group at the wide-angle end [mm]

[0062] When the imaging magnification of the rear lens group GR, which has negative refractive power, is increased, the focal length of each lens group arranged closer to the object than the rear lens group GR can be shortened, which is advantageous for reducing the overall lens length.

[0063] If the lower limit of condition (8) is exceeded and the negative refractive power of the rear lens group GR becomes large, this is advantageous for size reduction, but it becomes difficult to maintain sufficient optical performance.

[0064] By setting the lower limit of the above-mentioned conditional expression (8) to −0.004, the above-mentioned effect can be achieved more reliably.

[0065] In the large-aperture zoom lens of this embodiment, the rear lens group GR is made up of one lens group, and the rear lens group GR is made up of, in order from the object side, a lens unit RF1 having a positive refractive power and a lens unit RR1 having a negative refractive power, the lens unit RF1 has at least a positive lens with a convex surface facing the object side closest to the object side, and the lens unit RR1 has at least one negative lens closest to the image side. Also, the following conditional formula (9) is satisfied. (9) -2.0 <fRF1 / fRR1<0.0 Where: fRF1: focal length of lens unit RF1 fRR1: focal length of lens unit RR1

[0066] The rear lens group GR has a lens unit RF1, which has at least a positive lens with a convex surface facing the object side and has a positive refractive power as a whole, disposed closest to the object side, and thus the light beam diameter of the rear lens group GR can be reduced, and therefore the outer diameter around the mount of the camera body can be prevented from becoming large. Furthermore, the lens unit RR1, which has at least one negative lens closest to the image side and has a negative refractive power as a whole, can be disposed closest to the image side, and thus the exit angle of off-axis light beams can be appropriately controlled, and therefore the curvature of field can be easily improved.

[0067] If the lower limit of condition (9) is exceeded and the positive refractive power of the lens unit RF1 becomes small, the ray height of the lens closest to the image plane in the image-side lens group GR becomes too large, making it difficult to arrange the lenses around the mount of the camera body. Also, since the negative refractive power of the lens unit RR1 becomes too large, the negative refractive power of the rear lens group GR becomes large, which is advantageous for reducing the overall lens length, but makes it difficult to correct aberrations.

[0068] If the upper limit of condition (9) is exceeded and the positive refractive power of the lens unit RF1 becomes too large, the refractive power of the rear lens group GR becomes positive, making it difficult to reduce the overall lens length, and if the negative refractive power of the lens unit RR1 becomes too small, it becomes difficult to improve the curvature of field.

[0069] By limiting the lower limit of the above-mentioned conditional expression (9) to −1.6 and the upper limit to −1.1, the above-mentioned effect can be achieved more reliably.

[0070] In the large aperture zoom lens of this embodiment, the rear lens group GR is composed of two lens groups, and the distance between the two lens groups increases when zooming from the wide-angle end to the telephoto end, which changes the spherical aberration and astigmatism to the under side in the intermediate range and the telephoto end range of the zoom range, thereby making it possible to appropriately correct the change in the curvature of field when zooming.

[0071] In the large-aperture zoom lens of this embodiment, the two lens groups in the rear lens group GR are, in order from the object side, a lens group RF2 having a positive refractive power and a lens group RR2 having a negative refractive power, the lens group RF2 has at least a positive lens with a convex surface facing the object side closest to the object side, and the lens group RR2 has at least one negative lens closest to the image side, and satisfies the following conditional expressions (10) and (11). (10) -2.0 <fRF2 / fRR2<0.0 (11) 0.5 <RWD / RTD<1.0 Where: fRF2: focal length of lens group RF2 fRR2: focal length of lens group RR2 RWD: composite thickness on the optical axis of the rear lens group GR at the wide-angle end RTD: composite thickness on the optical axis of the rear lens group GR at the telephoto end

[0072] The rear lens group GR has a positive lens with a convex surface facing the object side and an overall positive refractive power, and by arranging the lens group RF2 closest to the object side, the light diameter of the rear lens group GR can be reduced, and therefore the outer diameter around the mount of the camera body can be prevented from becoming large. Furthermore, by arranging the lens group RR2 closest to the image side, the exit angle of off-axis light can be appropriately controlled, and therefore the curvature of field can be easily improved over the entire zoom range.

[0073] If the lower limit of condition (10) is exceeded and the positive refractive power of the lens group RF2 becomes small, the ray height of the lens group RR2, which is the lens group GR closest to the image plane, becomes too large, making it difficult to arrange the lenses around the mount of the camera body. Also, since the negative refractive power of the lens group RR2 becomes too large, the negative refractive power of the rear lens group GR becomes large, which is advantageous for reducing the overall lens length, but makes it difficult to correct aberrations.

[0074] If the upper limit of condition (10) is exceeded and the positive refractive power of the lens group RF2 becomes large, the refractive power of the rear lens group GR becomes positive, making it difficult to reduce the overall lens length, and if the negative refractive power of the lens group RR2 becomes small, it becomes difficult to improve the curvature of field.

[0075] By limiting the lower limit of the above-mentioned conditional expression (10) to −1.4 and the upper limit to −1.1, the above-mentioned effect can be ensured.

[0076] If the lower limit of conditional expression (11) is exceeded and the amount of movement of lens group RF2 during zooming increases, causing the combined thickness on the optical axis of the rear lens group GR at the telephoto end to become longer, the distance between the focusing lens LF and the rear lens group GR when focusing on a close-up object becomes too short, making it difficult to install a movable mechanism for moving the focusing lens LF.

[0077] If the upper limit value of conditional expression (11) is exceeded and the composite thickness on the optical axis of the rear lens group GR at the wide-angle end becomes long, the distance between the lens group RF2 and the lens group RR2 will be large at the wide-angle end and small at the telephoto end, making it impossible to obtain the effect of correcting the field curvature due to floating.

[0078] By limiting the lower limit of the above-mentioned conditional expression (11) to 0.85 and the upper limit to 0.95, the above-mentioned effect can be ensured.

[0079] Next, the lens configuration of the large aperture zoom lens of this embodiment will be described. In the following description, the lens configuration will be described in order from the object side to the image side. EXAMPLES

[0080] FIG. 1 is a lens configuration diagram of a large-aperture zoom lens according to a first embodiment of the present invention.

[0081] The large-aperture zoom lens of Example 1 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 1, the rear lens group GR is composed of a sixth lens group G6.

[0082] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

[0083] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0084] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0085] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0086] The third lens group G3 is composed of a biconvex lens L8 and a cemented lens made up of a biconvex lens L9 and a plano-concave lens L10 with its concave surface facing the object side.

[0087] The fourth lens group G4 is composed of a biconvex lens L11 as a lens group G41, and a positive meniscus lens L12 with its concave surface facing the object side as a lens G42.

[0088] The fifth lens group G5 is composed of a negative meniscus lens L13 having a convex surface facing the object side, as a focusing lens LF.

[0089] The sixth lens group G6 includes a lens unit RF1 which is a cemented lens having a biconvex lens L14 and a biconcave lens L15, both having positive refractive power, and a lens unit RR1 which is a biconcave lens L16 having negative refractive power. EXAMPLES

[0090] FIG. 8 is a lens configuration diagram of a large-aperture zoom lens according to a second embodiment of the present invention.

[0091] The large-aperture zoom lens of Example 2 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 2, the rear lens group GR is composed of a sixth lens group G6.

[0092] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

[0093] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0094] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0095] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0096] The third lens group G3 is composed of a biconvex lens L8, a cemented lens made up of a biconvex lens L9 and a negative meniscus lens L10 with its concave surface facing the object side, and a plano-convex lens L11 with its convex surface facing the object side.

[0097] The fourth lens group G4 is composed of a lens group G41, which is a cemented lens of a negative meniscus lens L12 with a convex surface facing the object side and a positive meniscus lens L13 with a convex surface facing the object side, a biconvex lens L14, and a lens G42, which is a positive meniscus lens L15 with a concave surface facing the object side.

[0098] The fifth lens group G5 is composed of a negative meniscus lens L16 having a convex surface facing the object side, as a focusing lens LF.

[0099] The sixth lens group G6 is composed of a lens unit RF1 including a positive meniscus lens L17 with a convex surface facing the object side, and a lens unit RR1 including a negative meniscus lens L18 with a convex surface facing the object side, and a biconcave lens L19. EXAMPLES

[0100] FIG. 15 is a lens configuration diagram of a large-aperture zoom lens according to a third embodiment of the present invention.

[0101] The large-aperture zoom lens of Example 3 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 3, the rear lens group GR is composed of a sixth lens group G6.

[0102] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

[0103] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0104] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0105] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0106] The third lens group G3 is composed of a biconvex lens L8 and a cemented lens made up of a biconvex lens L9 and a plano-concave lens L10 with its concave surface facing the object side.

[0107] The fourth lens group G4 is composed of a biconvex lens L11 as a lens group G41, and a positive meniscus lens L12 with its concave surface facing the object side as a lens G42.

[0108] The fifth lens group G5 is composed of a negative meniscus lens L13 having a convex surface facing the object side, as a focusing lens LF.

[0109] The sixth lens group G6 includes a lens unit RF1 which is a cemented lens having a biconvex lens L14 and a biconcave lens L15, both having positive refractive power, and a lens unit RR1 which is a biconcave lens L16 having negative refractive power. EXAMPLES

[0110] FIG. 22 is a lens configuration diagram of a large-aperture zoom lens according to a fourth embodiment of the present invention.

[0111] The large-aperture zoom lens of Example 4 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 3, the rear lens group GR is composed of a sixth lens group G6.

[0112] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

[0113] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0114] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0115] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0116] The third lens group G3 is composed of a biconvex lens L8 and a cemented lens made up of a biconvex lens L9 and a negative meniscus lens L10 with its concave surface facing the object side.

[0117] The fourth lens group G4 is composed of a biconvex lens L11 as a lens group G41, and a positive meniscus lens L12 with its concave surface facing the object side as a lens G42.

[0118] The fifth lens group G5 is composed of a negative meniscus lens L13 having a convex surface facing the object side, as a focusing lens LF.

[0119] The sixth lens group G6 is composed of a biconvex lens L14 as a lens unit RF1, a biconcave lens L15 as a lens unit RR1, and a plano-concave lens with its concave surface facing the object side. EXAMPLES

[0120] FIG. 29 is a lens configuration diagram of a large-aperture zoom lens according to a fifth embodiment of the present invention.

[0121] The large-aperture zoom lens of Example 5 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 5, the rear lens group GR is composed of a sixth lens group G6 and a seventh lens group G7.

[0122] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, the distance between the fifth lens group G5 and the sixth lens group G6 increases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases.

[0123] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0124] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0125] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0126] The third lens group G3 is composed of a biconvex lens L8 and a cemented lens consisting of a biconvex lens L9 and a biconcave lens L10.

[0127] The fourth lens group G4 is composed of a biconvex lens L11 as a lens group G41, and a positive meniscus lens L12 with its concave surface facing the object side as a lens G42.

[0128] The fifth lens group G5 is composed of a negative meniscus lens L13 having a convex surface facing the object side, as a focusing lens LF.

[0129] The sixth lens group G6 is composed of a cemented lens having a biconvex lens L14 and a biconcave lens L15 as a lens group RF2, and the seventh lens group G7 is composed of a biconcave lens L16 having a negative refractive power as a lens group RR2. EXAMPLES

[0130] FIG. 36 is a lens configuration diagram of a large-aperture zoom lens according to a sixth embodiment of the present invention.

[0131] The large-aperture zoom lens of Example 6 is composed of a first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a fifth lens group G5 with negative refractive power. In Example 6, the rear lens group GR is composed of a sixth lens group G6 and a seventh lens group G7.

[0132] During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 is fixed relative to the image surface. Also, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, the distance between the fifth lens group G5 and the sixth lens group G6 increases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases.

[0133] An aperture stop S is disposed on the object side of the third lens group G3, the fourth lens group G4 consists of a lens group G41 having positive refractive power and a lens G42 having positive refractive power and an aspheric surface, and the fifth lens group G5 consists of a focusing lens LF having negative refractive power, and when focusing from an object at infinity to an object at a close distance, the focusing lens LF moves along the optical axis toward the image plane side.

[0134] The first lens group G1 is composed of a cemented lens made up of a negative meniscus lens L1 with a convex surface facing the object side and a biconvex lens L2, and a positive meniscus lens L3 with a convex surface facing the object side.

[0135] The second lens group G2 is composed of a negative meniscus lens L4 with a convex surface facing the object side, a cemented lens made up of a biconcave lens L5 and a biconvex lens L6, and a negative meniscus lens L7 with a concave surface facing the object side.

[0136] The third lens group G3 is composed of a biconvex lens L8 and a cemented lens made up of a biconvex lens L9 and a concave meniscus lens L10 with its concave surface facing the object side.

[0137] The fourth lens group G4 is composed of a biconvex lens L11 as a lens group G41, and a positive meniscus lens L12 with its concave surface facing the object side as a lens G42.

[0138] The fifth lens group G5 is composed of a negative meniscus lens L13 having a convex surface facing the object side, as a focusing lens LF.

[0139] The sixth lens group G6 is composed of a biconvex lens L14 having positive refractive power as the lens group RF2, and the seventh lens group G7 is composed of a plano-concave lens L15 having negative refractive power with its flat surface facing the object side as the lens group RR2, and a negative meniscus lens L16 having its concave surface facing the object side.

[0140] Numerical examples of the large aperture zoom lens of this embodiment will be described below.

[0141] In [Surface Data], the surface number is the lens surface or aperture stop number counted from the object side, r is the radius of curvature of each surface, d is the spacing between each surface, nd is the refractive index for the d line (wavelength 587.56 nm), and vd is the Abbe number for the d line.

[0142] An asterisk (*) next to a surface number indicates that the lens surface is aspheric, and BF stands for back focus.

[0143] The (diaphragm) next to a surface number indicates that an aperture diaphragm is located at that position. The radius of curvature for the plane or aperture diaphragm is marked as ∞ (infinity).

[0144] [Aspheric Data] shows the values ​​of each coefficient that gives the aspheric shape of lens surfaces marked with an * in [Surface Data]. The shape of an aspheric surface is expressed by the following formula, where y is the displacement from the optical axis in a direction perpendicular to the optical axis, z is the displacement (sag) from the intersection of the aspheric surface and the optical axis in the direction of the optical axis, r is the radius of curvature of the reference sphere, K is the Conic coefficient, and A4, A6, ..., and A16 are the aspheric coefficients of 4th to 16th orders, respectively.

[0145] TIFF0007630814000001.tif19137

[0146] [Various Data] shows values ​​such as the zoom ratio and focal length at each focal length state.

[0147] [Variable Distance Data] shows the variable distance and BF values ​​for each focal length state.

[0148] [Lens Group Data] indicates the surface number of each lens group closest to the object and the composite focal length of the entire lens group.

[0149] In addition, for all of the values ​​of the following specifications, the focal length f, radius of curvature r, distance d between each surface, and other lengths are expressed in millimeters (mm) unless otherwise specified; however, since the optical system can obtain the same optical performance with proportional magnification and proportional reduction, this is not limited to this.

[0150] Also, a list of values ​​corresponding to the conditional expressions in each of these numerical examples is shown.

[0151] In the longitudinal and lateral aberration diagrams corresponding to the numerical examples, d, g and C represent the d-line, g-line and C-line, respectively, and ΔS and ΔM represent the sagittal and meridional image surfaces, respectively.

[0152] Numerical Example 1 Unit: mm [Face data] Surface number rd nd vd 1 500.0000 1.8000 1.98613 16.48 2 270.4400 4.9300 1.48749 70.44 3 -450.0700 0.1500 4 56.2500 8.7900 1.48749 70.44 5 209.3700 (d5) 6* 200.0000 1.8000 1.85135 40.10 7* 21.3000 8.0200 8 -43.1100 1.0000 1.59282 68.62 9 22.4200 7.8400 1.77047 29.74 10 -64.5900 3.0300 11 -24.0800 0.9000 1.49700 81.61 12 -90.1400 (d12) 13(Aperture) ∞ 1.2000 14 42.6900 4.7600 1.49700 81.61 15 -76.6400 0.1500 16 38.2000 9.2900 1.43700 95.10 17 -27.0500 0.9000 1.90043 37.37 18∞ (d18) 19 25.5400 9.0000 1.43700 95.10 20 -36.9400 0.3500 21* 1000.0000 2.9100 1.59201 67.02 22* -45.7500 (d22) 23* 293.2900 1.2000 1.69350 53.20 24* 30.9600 (d24) 25 46.0500 5.5800 1.87071 40.73 26 -326.8800 1.2000 1.51742 52.15 27 34.0000 5.3600 28 -201.6100 1.2000 1.56732 42.84 29 100.0000 (BF) image plane [Aspheric data] 6th 7th 21st 22nd K 0.00000 -1.00000 0.00000 0.00000 A4 9.64570E-06 2.25950E-05 -3.46960E-05 -3.56650E-06 A6 -2.46570E-08 -4.04980E-08 -6.29210E-08 -1.52480E-08 A8 8.35530E-11 8.62340E-10 1.83020E-09 1.48200E-09 A10 -1.48070E-13 -6.66800E-12 -4.65270E-12 -3.25320E-12 A12 1.22550E-16 2.99900E-14 0.00000E+00 0.00000E+00 A14 0.00000E+00 -5.06100E-17 0.00000E+00 0.00000E+00 23rd page 24th page K 0.00000 0.00000 A4 3.03570E-05 3.12540E-05 A6 -2.12000E-07 -2.26890E-07 A8 6.14320E-10 7.70270E-10 A10 0.00000E+00 0.00000E+00 A12 0.00000E+00 0.00000E+00 A14 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.75 Wide Angle Mid-Telephoto Focal length 24.72 39.76 67.98 F-number 2.92 2.92 2.92 Full angle of view 2ω 85.24 56.96 34.33 Image height Y 21.63 21.63 21.63 Lens total length 135.00 145.60 171.09 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 12.6100 34.9600 d12 16.4800 7.4300 1.7100 d18 8.5600 4.5900 2.7000 d22 2.4000 2.0700 1.9000 d24 7.0800 19.9412 30.8878 BF 17.6206 17.6036 17.5749 [Lens group data] Group starting plane focal length G1 1 130.36 G2 6 -20.62 G3 14 64.03 G4 19 26.36 G5 23 -50.01 G6 25 -559.05 G41 19 36.14 G42 21 80.89 RF1 25 172.19 RR1 28 -117.66

[0153] Numerical Example 2 Unit: mm [Face data] Surface number rd nd vd 1 500.0000 1.8000 1.94595 17.98 2 253.4800 4.6800 1.48749 70.44 3 -438.1900 0.1500 4 53.5500 8.3100 1.48749 70.44 5 230.8900 (d5) 6* 328.4400 1.8000 1.85135 40.10 7* 22.1600 8.0500 8 -42.8100 1.0000 1.59282 68.62 9 23.7800 5.9900 1.77047 29.74 10 -74.4200 3.0500 11 -22.2800 0.9000 1.43700 95.10 12 -102.8000 (d12) 13(Aperture) ∞ 1.2000 14 72.6000 2.5600 1.72916 54.67 15 -600.9100 0.1500 16 39.5700 7.5300 1.43700 95.10 17 -29.2800 1.0000 1.88300 40.80 18 -178.4600 0.4400 19 110.2300 2.0800 1.43700 95.10 20∞ (d20) 21 55.2700 1.0000 1.80420 46.50 22 28.7800 5.2900 1.43700 95.10 23 1235.8300 0.1500 24 24.6800 9.2900 1.43700 95.10 25 -46.1500 0.3500 26* -1000.0000 2.6000 1.59201 67.02 27* -51.9400 (d27) 28* 151.5900 1.2000 1.69350 53.20 29* 26.9800 (d29) 30 41.1300 5.2100 1.91082 35.25 31 307.0700 0.1500 32 97.7100 1.2000 1.64769 33.84 33 29.3200 5.6800 34 -561.1500 1.2000 1.67300 38.26 35 100.0000 (BF) Image plane ∞ [Aspheric data] 6th 7th 26th 27th K 0.00000 -1.00000 0.00000 0.00000 A4 2.74630E-05 3.92360E-05 -3.98820E-05 -1.15420E-05 A6 -2.05280E-07 -1.46350E-07 -6.92930E-10 2.75680E-08 A8 1.21630E-09 2.95280E-10 1.42530E-09 1.17220E-09 A10 -4.41650E-12 6.50300E-12 -3.40870E-12 -2.36990E-12 A12 9.59160E-15 -5.18360E-14 0.00000E+00 0.00000E+00 A14 -1.13240E-17 1.84260E-16 0.00000E+00 0.00000E+00 A16 5.58660E-21 -2.87740E-19 0.00000E+00 0.00000E+00 Page 28 Page 29 K 0.00000 0.00000 A4 3.23770E-05 3.31730E-05 A6 -4.21570E-07 -4.60990E-07 A8 3.21000E-09 3.76160E-09 A10 -1.31270E-11 -1.61700E-11 A12 2.37100E-14 3.40450E-14 A14 0.00000E+00 -1.15100E-17 A16 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.75 Wide Angle Mid-Telephoto Focal length 24.72 39.88 68.02 F-number 2.92 2.92 2.92 Full angle of view 2ω 85.13 56.00 34.31 Image height Y 21.63 21.63 21.63 Lens total length 135.00 147.22 170.64 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 14.3780 30.8700 d12 15.3700 6.9962 1.5000 d20 6.8800 3.2109 0.8100 d27 2.4600 2.5700 1.9000 d29 7.1500 18.4727 33.9716 BF 17.6251 17.5782 17.5747 [Lens group data] Group starting plane focal length G1 1 120.56 G2 6 -19.16 G3 14 60.42 G4 21 27.89 G5 28 -47.51 G6 30 -576.23 G41 21 36.84 G42 26 92.45 RF1 30 51.66 RR1 32 -41.64

[0154] Numerical Example 3 Unit: mm [Face data] Surface number rd nd vd 1 397.6900 1.6000 1.94595 17.98 2 183.2800 5.0000 1.48749 70.44 3 -241.3100 0.1500 4 44.3100 7.6300 1.48749 70.44 5 200.0000 (d5) 6* 200.0000 1.4500 1.85135 40.10 7* 20.9400 5.9200 8 -43.9100 0.9000 1.59282 68.62 9 19.6400 5.4200 1.77047 29.74 10 -69.0900 2.5600 11 -23.0700 0.9000 1.49700 81.61 12 -100.8600 (d12) 13(Aperture) ∞ 1.2000 14 48.6900 3.0600 1.69680 55.46 15 -179.5700 0.1500 16 38.0000 6.6900 1.43700 95.10 17 -23.8300 0.8500 1.91082 35.25 18∞ (d18) 19 24.0900 8.3100 1.43700 95.10 20 -31.5800 0.3500 21* -1000.0000 2.8000 1.59201 67.02 22* -41.1200 (d22) 23* 200.0000 1.1500 1.69350 53.20 24* 29.4800 (d24) 25 61.8100 6.8400 1.88300 40.80 26 -45.8100 1.0000 1.53172 48.84 27 79.4400 4.4300 28 -46.9600 1.0000 1.67300 38.26 29 100.0000 (BF) Image plane ∞ [Aspheric data] 6th 7th 21st 22nd K 0.00000 -1.00000 0.00000 0.00000 A4 1.65170E-05 3.14480E-05 -4.64340E-05 -1.03570E-05 A6 -6.23420E-08 -8.05320E-08 -7.34270E-08 5.23300E-10 A8 2.51840E-10 1.94400E-09 2.38778E-09 1.82680E-09 A10 -4.49430E-13 -2.18990E-11 -6.59680E-12 -4.24950E-12 A12 2.85710E-16 1.40870E-13 0.00000E+00 0.00000E+00 A14 0.00000E+00 -3.39560E-16 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 23rd page 24th page K 0.00000 0.00000 A4 2.56020E-05 2.57690E-05 A6 -2.15850E-07 -2.43820E-07 A8 7.82740E-10 1.07610E-09 A10 0.00000E+00 0.00000E+00 A12 0.00000E+00 0.00000E+00 A14 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.35 Wide Angle Mid-Telephoto Focal length 28.81 40.01 67.69 F-number 2.92 2.92 2.92 Full angle of view 2ω 75.92 56.06 33.85 Image height Y 21.63 21.63 21.63 Lens length 120.04 126.08 142.66 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 8.9300 24.1000 d12 12.4600 7.0900 1.5200 d18 7.3300 5.1500 3.1500 d22 2.2700 2.5000 1.9000 d24 7.4900 13.4638 23.0231 BF 19.6292 19.5884 19.6020 [Lens group data] Group starting plane focal length G1 1 94.26 G2 6 -20.08 G3 14 79.02 G4 19 23.82 G5 23 -50.00 G6 25 -341.49 G41 19 32.76 G42 21 72.36 RF1 25 65.34 RR1 28 -47.35

[0155] Numerical Example 4 Unit: mm [Face data] Surface number rd nd vd 1 248.5800 1.8000 1.92286 20.88 2 146.1800 6.5500 1.43700 95.10 3 -353.6600 0.1500 4 57.8700 7.6700 1.61997 63.88 5 200.0000 (d5) 6* 140.0000 1.8000 1.85135 40.10 7* 22.6800 7.4100 8 -50.9200 1.0000 1.59282 68.62 9 21.3400 6.6000 1.77047 29.74 10 -86.6500 2.6400 11 -26.9700 0.9000 1.55032 75.50 12 -105.9200 (d12) 13(Aperture) ∞ 1.2000 14 46.6900 3.5400 1.59349 67.00 15 -172.1500 1.6200 16 39.7000 8.8400 1.43700 95.10 17 -25.6700 1.0000 1.91082 35.25 18 -324.4400 (d18) 19 29.3700 7.7000 1.43700 95.10 20 -34.3200 0.3500 21* -1000.0000 2.5000 1.55332 71.68 22* -44.1100 (d22) 23* 939.0000 1.2000 1.69350 53.20 24* 33.2000 (d24) 25 42.2800 5.0700 1.95375 32.32 26 -415.0000 0.6500 27 -216.8300 1.2000 1.59270 35.45 28 31.9600 6.0800 29 -63.9900 1.2000 1.51742 52.15 30∞(BF) Image plane ∞ [Aspheric data] 6th 7th 21st 22nd K 0.00000 -1.00000 0.00000 0.00000 A4 1.09500E-05 2.35320E-05 -4.66400E-05 -1.95650E-05 A6 -4.03450E-08 -4.78520E-08 -1.53460E-07 -1.06070E-07 A8 1.00820E-10 8.87380E-10 1.63920E-09 1.34650E-09 A10 1.94880E-13 -1.03180E-11 -2.56090E-12 -1.88290E-12 A12 -1.76500E-15 7.84178E-14 0.00000E+00 0.00000E+00 A14 3.96060E-18 -2.96670E-16 0.00000E+00 0.00000E+00 A16 -2.99700E-21 4.49820E-19 0.00000E+00 0.00000E+00 23rd page 24th page K 0.00000 0.00000 A4 6.55390E-05 6.85350E-05 A6 -7.34180E-07 -7.54910E-07 A8 4.80150E-09 4.88950E-09 A10 -1.68400E-11 -1.64030E-11 A12 2.50760E-14 2.38980E-14 A14 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.90 Wide Angle Mid-Telephoto Focal length 28.79 49.98 83.51 F-number 2.92 2.92 2.92 Full angle of view 2ω 75.61 45.42 27.77 Image height Y 21.63 21.63 21.63 Lens length 135.02 146.97 164.94 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 16.8200 34.1000 d12 18.0000 7.4500 1.5000 d18 8.0000 4.3300 2.7300 d22 2.2500 2.7200 1.9000 d24 7.5000 17.9506 26.9678 BF 17.6146 17.5433 17.5817 [Lens group data] Group starting plane focal length G1 1 106.60 G2 6 -22.44 G3 14 70.42 G4 19 27.03 G5 23 -49.65 G6 25 -1002.69 G41 19 37.60 G42 21 83.32 RF1 25 40.46 RR1 27 -32.76

[0156] Numerical Example 5 Unit: mm [Face data] Surface number rd nd vd 1 500.0000 1.6000 1.94595 17.98 2 205.4700 4.7900 1.48749 70.44 3 -229.9400 0.1500 4 45.2200 7.4900 1.48749 70.44 5 200.0000 (d5) 6* 110.7700 1.4500 1.85135 40.10 7* 19.8700 6.0700 8 -42.4000 0.9000 1.59282 68.62 9 19.0500 5.3700 1.77047 29.74 10 -80.6700 2.7700 11 -22.1700 0.9000 1.49700 81.61 12 -100.0000 (d12) 13(Aperture) ∞ 1.2000 14 44.9400 3.8700 1.69680 55.46 15 -82.6600 0.1500 16 44.7900 6.5600 1.43700 95.10 17 -23.5300 0.8500 1.91082 35.25 18 779.5300 (d18) 19 24.9200 8.2800 1.43700 95.10 20 -30.8600 0.3500 21* -1000.0000 2.4300 1.59201 67.02 22* -45.0500 (d22) 23* 179.6400 1.1500 1.69350 53.20 24* 28.3400 (d24) 25 60.7700 6.1100 1.88300 40.80 26 -54.3400 1.0000 1.62004 36.30 27 96.2900 (d27) 28 -46.6400 1.0000 1.51680 64.20 29 100.0000 (BF) Image plane ∞ [Aspheric data] 6th 7th 21st 22nd K 0.00000 -1.00000 0.00000 0.00000 A4 1.70550E-05 3.56250E-05 -4.39970E-05 -1.03710E-05 A6 -6.57480E-08 -8.78860E-08 -1.12110E-07 -5.23190E-08 A8 2.35300E-10 2.31210E-09 2.80750E-09 2.39410E-09 A10 -2.71730E-13 -2.76770E-11 -8.04100E-12 -6.22300E-12 A12 -4.64180E-17 1.84700E-13 0.00000E+00 0.00000E+00 A14 0.00000E+00 -4.54500E-16 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00 23rd page 24th page K 0.00000 0.00000 A4 1.77830E-05 1.67490E-05 A6 -1.63200E-07 -1.84270E-07 A8 6.14250E-10 8.30600E-10 A10 0.00000E+00 0.00000E+00 A12 0.00000E+00 0.00000E+00 A14 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.35 Wide Angle Mid-Telephoto Focal length 28.79 40.00 67.69 F-number 2.92 2.92 2.92 Full angle of view 2ω 75.80 55.88 33.85 Image height Y 21.63 21.63 21.63 Lens length 120.00 126.94 144.45 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 9.4400 24.5800 d12 11.9800 6.9500 1.5000 d18 7.6600 5.2900 3.0000 d22 2.2700 2.5000 1.9000 d24 7.5200 13.2500 22.5000 d27 5.0300 5.4900 6.9476 BF 19.6023 19.5788 19.5794 [Lens group data] Group starting plane focal length G1 1 97.33 G2 6 -19.19 G3 14 63.46 G4 19 24.50 G5 23 -48.67 G6 25 76.44 G7 28 -61.40 G41 19 33.04 G42 21 79.61 GRW 25 -886.35 GRT 25 -1389.51 RF2 25 76.44 RR2 28 -61.40

[0157] Numerical Example 6 Unit: mm [Face data] Surface number rd nd vd 1 183.6900 1.8000 1.92286 20.88 2 120.2300 6.6500 1.43700 95.10 3 -606.0000 0.1500 4 56.6200 7.7800 1.61997 63.88 5 205.4000 (d5) 6* 116.1800 1.8000 1.85135 40.10 7* 20.9900 7.2300 8 -51.7800 1.0000 1.59282 68.62 9 20.9600 6.3000 1.77047 29.74 10 -91.5400 2.7200 11 -25.8300 0.9000 1.55032 75.50 12 -114.8000 (d12) 13(Aperture) ∞ 1.2000 14 46.3700 3.8000 1.59349 67.00 15 -113.9200 1.1900 16 42.8030 8.7500 1.43700 95.10 17 -24.8400 1.0000 1.91082 35.25 18 -241.5300 (d18) 19 29.7300 7.7000 1.43700 95.10 20 -33.8800 0.3500 21* -1000.0000 2.5000 1.55332 71.68 22* -45.9900 (d22) 23* 1000.0000 1.2000 1.69350 53.20 24* 33.5000 (d24) 25 45.1100 5.5000 1.95375 32.32 26 -246.0000 0.8100 27 ∞ 1.2000 1.56732 42.84 28 31.1200 (d28) 29 -32.7600 1.2000 1.75211 25.05 30 -64.6500 (BF) Image plane ∞ [Aspheric data] 6th 7th 21st 22nd K 0.00000 -1.00000 0.00000 0.00000 A4 5.56110E-06 1.90110E-05 -4.38890E-05 -1.70120E-05 A6 -1.43250E-08 -1.83100E-08 -1.09780E-07 -7.76980E-08 A8 2.94330E-11 6.79460E-10 1.25680E-09 1.05710E-09 A10 2.27810E-13 -8.27070E-12 -1.87720E-12 -1.36130E-12 A12 -1.45300E-15 6.60750E-14 0.00000E+00 0.00000E+00 A14 3.27400E-18 -2.63920E-16 0.00000E+00 0.00000E+00 A16 -2.56380E-21 4.23000E-19 0.00000E+00 0.00000E+00 23rd page 24th page K 0.00000 0.00000 A4 5.16740E-05 5.26540E-05 A6 -6.27980E-07 -6.45670E-07 A8 4.53200E-09 4.71380E-09 A10 -1.78480E-11 -1.83790E-11 A12 3.08590E-14 3.22850E-14 A14 0.00000E+00 0.00000E+00 A16 0.00000E+00 0.00000E+00 [Various data] Zoom ratio 2.90 Wide Angle Mid-Telephoto Focal length 28.79 50.39 83.39 F-number 2.92 2.92 2.92 Full angle of view 2ω 75.90 44.79 27.76 Image height Y 21.63 21.63 21.63 Lens length 135.01 147.86 164.44 [Variable interval data] Wide Angle Mid-Telephoto d5 1.5000 18.5000 33.0000 d12 17.1200 7.3000 1.5000 d18 8.3900 4.6300 2.7800 d22 2.0000 2.4800 1.9000 d24 7.5000 15.7216 25.8069 d26 0.8100 1.5700 1.8000 BF 17.5983 17.5658 17.5615 [Lens group data] Group starting plane focal length G1 1 102.53 G2 6 -20.59 G3 14 64.27 G4 19 27.36 G5 23 -50.01 G6 25 40.34 G7 27 -32.38 G41 19 37.62 G42 21 87.04 GRW 25 -1006.70 GRT 25 -4248.60 RF2 25 40.34 RR2 27 -32.38

[0158] Conditional expression corresponding value ex1 ex2 ex3 ex4 ex5 ex6 (1) f5 / f4 -1.9 -1.7 -2.1 -1.8 -2.0 -1.8 (2) f3 / f4 2.4 2.2 3.3 2.6 2.6 2.3 (3) f1 / f2 -6.3 -6.3 -4.7 -4.8 -5.1 -5.0 (4) νd1n 16.48 17.98 17.98 20.88 17.98 20.88 (5) νd1p 70.44 70.44 70.44 95.1 70.44 95.1 (6) νd1p / νd1 4.3 3.9 3.9 4.6 3.9 4.6 (7) f41 / f42 0.45 0.40 0.45 0.45 0.42 0.43 (8) 1 / fRW -0.002 -0.002 -0.003 -0.001 -0.001 -0.001 (9) fRF1 / fRR -1.5 -1.2 -1.4 -1.2 (10) fRF2 / fRR2 -1.2 -1.2 (11) RWD / RTD 0.87 0.94 [Explanation of symbols]

[0159] G1 First lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group GR rear lens group LF Focusing Lens S aperture stop I image plane

Claims

1. The optical system is made up of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a rear lens group GR having a negative refractive power including one or more lens groups. The fifth lens group G5 is made up of a focusing lens LF made up of a negative meniscus lens having a convex surface facing the object side, which moves toward the image surface side when focusing from an object at infinity to an object at a close distance. When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 and the second lens group G2 are moved toward the image surface side. a distance between the second lens group G2 and the third lens group G3 increases, a distance between the third lens group G3 and the fourth lens group G4 decreases, a distance between the fourth lens group G4 and the fifth lens group G5 changes, a distance between the fifth lens group G5 and the rear lens group GR increases, a lens of the rear lens group GR closest to an image surface is fixed with respect to the image surface, the third lens group G3 and the fourth lens group G4 move toward the object side, and the following conditional expression is satisfied: (1) -3.0<f5 / f4<-1.0 (2) 1.0<f3 / f4<5.0 Where: f3: focal length of the third lens group G3 f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

2. The optical system is made up of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a rear lens group GR having negative refractive power including one or more lens groups. The fifth lens group G5 is made up of a focusing lens LF made up of a negative meniscus lens having a convex surface facing the object side, which moves toward the image plane side when focusing from an object at infinity to an object at a close distance. When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 and a distance between the second lens group G2 and the third lens group G3 is decreased, a distance between the third lens group G3 and the fourth lens group G4 is decreased, a distance between the fourth lens group G4 and the fifth lens group G5 is changed, a distance between the fifth lens group G5 and the rear lens group GR is increased, a lens of the rear lens group GR closest to an image surface is fixed with respect to an image surface, and the first lens group G1 moves toward the object side; and the large-aperture zoom lens satisfies the following condition: (1) -3.0<f5 / f4<-1.0 (3) -10.0<f1 / f2<-3.0 Where: f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

3. The optical system is made up of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a rear lens group GR having a negative refractive power including one or more lens groups. The rear lens group GR is made up of two lens groups. The fifth lens group G5 includes a focusing lens LF consisting of a negative meniscus lens having a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to an object at a close distance. and, during zooming from the wide-angle end to the telephoto end, a distance between the first lens group G1 and the second lens group G2 increases, a distance between the second lens group G2 and the third lens group G3 decreases, a distance between the third lens group G3 and the fourth lens group G4 decreases, a distance between the fourth lens group G4 and the fifth lens group G5 changes, a distance between the fifth lens group G5 and the rear lens group GR increases, and the distances between the two lens groups increase, and the following conditional expressions are satisfied: (1) -3.0<f5 / f4<-1.0 Where: f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

4. 3. The large-aperture zoom lens according to claim 1, wherein the rear lens group GR is composed of one lens group, the rear lens group GR being composed of, in order from the object side, a lens unit RF1 having positive refractive power and a lens unit RR1 having negative refractive power, the lens unit RF1 having at least a positive lens with a convex surface facing the object side, the lens unit RR1 having at least one negative lens, the lens unit RR1 having at least one negative lens, the lens unit RR1 having at least one negative lens, the lens unit GR satisfying the following conditional expression: (9) -2.0<fRF1 / fRR1<0.0 Where: fRF1: focal length of lens unit RF1 fRR1: focal length of lens unit RR1

5. 4. The large-aperture zoom lens according to claim 3, wherein the lens in the rear lens group GR located closest to the image plane is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

6. 6. The large-aperture zoom lens according to claim 3, wherein the two lens groups of the rear lens group GR are, in order from the object side, a lens group RF2 having positive refractive power and a lens group RR2 having negative refractive power, the lens group RF2 has at least a positive lens with a convex surface facing the object side, which is closest to the object side, and the lens group RR2 has at least one negative lens closest to the image side, and the following conditional expression is satisfied: (10) -2.0<fRF2 / fRR2<0.0 (11) 0.5<RWD / RTD<1.0 Where: fRF2: focal length of lens group RF2 fRR2: focal length of lens group RR2 RWD: composite thickness on the optical axis of the rear lens group GR at the wide-angle end RTD: composite thickness on the optical axis of the rear lens group GR at the telephoto end

7. 7. The large-aperture zoom lens according to claim 2, wherein the third lens group G3 and the fourth lens group G4 move toward the object side during zooming from the wide-angle end to the telephoto end, and the following conditional expression is satisfied: (2) 1.0<f3 / f4<5.0 Where: f3: focal length of the third lens group G3 f4: focal length of the fourth lens group G4

8. 8. The large-aperture zoom lens according to claim 1, wherein the first lens group G1 moves toward the object side during zooming from the wide-angle end to the telephoto end, and the following condition is satisfied: (3) -10.0<f1 / f2<-3.0 Where: f1: focal length of the first lens group G1 f2: focal length of the second lens group G2

9. 9. The large-aperture zoom lens according to claim 1, wherein the first lens group G1 comprises, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a positive lens L12 having a convex surface facing the object side, and a positive lens L13 having a convex surface facing the object side, and satisfies the following conditional expression: (4) νd1n<30.0 (5) 65.0<νd1p (6) 3.0<νd1p / νd1n Where: νd1n: ​​Abbe number of the negative meniscus lens L11 νd1p: the Abbe number of the positive lens having the lowest dispersion among the positive lens L12 and the positive lens L13

10. 10. The large-aperture zoom lens according to claim 1, wherein the fourth lens group G4 is composed of, in order from the object side, a lens group G41 having at least one positive lens and having positive refractive power as a whole, and a positive lens G42 having an aspheric surface, and wherein the following conditional expression is satisfied: (7) 0.3<f41 / f42<0.6 Where: f41: focal length of lens group G41 f42: focal length of positive lens G42

11. 11. The large-aperture zoom lens according to claim 1, wherein the following condition is satisfied: (8) -0.3<1 / fRW<0.0 Where: fRW: focal length of the rear lens group GR at the wide-angle end [mm]

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