Large aperture ratio zoom lens

Abstract

To provide a large aperture ratio zoom lens that is adaptive to a large-sized imaging device, is suppressed in change in angle of view upon focusing, and is suppressed in increase in size while facilitating the large aperture ratio.SOLUTION: A large aperture ratio zoom lens is composed of: a negative first lens group G1; a positive second lens group G2; an intermediate lens group GM having a plurality of lens group; and a negative final lens group GL. Upon zooming, an interval between the first lens group G1 and the second lens group G2 decreases, an interval between the second lens group G2 and the intermediate lens group GM varies, and an interval between the intermediate lens group GM and the final lens group GL varies. The intermediate lens group GM has a lens group GM1 of a negative lens M1, and a lens group GM2 of a positive lens M2, and upon zooming, an interval between the lens group GM1 of the negative lens M1 and the lens group GM2 of the positive lens M2 varies. An aperture diaphragm is adjacent to the intermediate lens group GM, or present within the intermediate lens group GM. The first lens group G1 has lens group G1a of a negative 1a, and a lens group G1b of a negative lens 1b, and upon zooming, the 1b lens group G1b moves to an object side, and the large aperture ratio zoom lens satisfies a prescribed condition.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a large aperture ratio zoom lens suitable for use as a photographing lens in an image pickup device such as a still camera or a video camera. [Background technology]

[0002] In recent years, cameras using large image sensors, such as cameras for filming movies, have become widespread. Lenses used in these cameras tend to avoid changes in the angle of view during focusing, and are designed to place the focus lens closer to the object than the zoom mechanism. However, when increasing the aperture ratio of a lens while accommodating a large image sensor, it becomes an issue to reduce the product size. Patent documents 1 to 3, for example, disclose zoom lenses that are compatible with large image sensors, have little change in the angle of view during focusing, and have a relatively large aperture ratio. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-028172 A [Patent Document 2] JP 2020-160265 A [Patent Document 3] JP 2022-123454 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Documents 1 and 2 take into consideration large image sensors, but there are issues with making the aperture ratio even larger. Patent Document 3 has a large aperture ratio, but there are issues with making it compatible with even larger image sensors. If an aperture ratio is made even larger than those of Patent Documents 1, 2, and 3, there is a problem that the optical system becomes larger.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a large aperture ratio zoom lens that is compatible with a large image sensor, suppresses change in the angle of view during focusing, and achieves a large aperture ratio while preventing the optical system from becoming large. [Means for solving the problem]

[0006] In order to achieve the above object, a large aperture ratio zoom lens embodying the present invention comprises, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM having a plurality of lens groups, and a final lens group GL with negative refractive power, and during zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the intermediate lens group GM changes, and the distance between the intermediate lens group GM and the final lens group GL changes. The lens has an M1 lens group GM1 with positive refractive power and an M2 lens group GM2 with positive refractive power, the distance between the M1 lens group GM1 and the M2 lens group GM2 changes when zooming from the wide-angle end to the telephoto end, an aperture stop is located adjacent to the intermediate lens group GM or within the intermediate lens group GM, and the first lens group G1 has, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power, and when focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and the following conditional formula is satisfied: (1) 0.10 < Δ1ab / SD1 < 0.90 Δ1ab: the distance parallel to the optical axis between the position of maximum effective ray height on the surface closest to the image side of the 1a lens group G1a and the position of maximum effective ray height on the surface closest to the object side of the 1b lens group G1b when focusing at infinity SD1: Maximum effective light height of the first lens group G1

[0007] In a large aperture ratio zoom lens embodying the present invention, when focusing from infinity to a close distance, the lenses other than the 1b lens group G1b may be fixed relative to the image plane.

[0008] In a large aperture ratio zoom lens embodying the present invention, the final lens group GL may be fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.

[0009] In addition, in a large aperture ratio zoom lens embodying the present invention, the 1a lens group G1a may have at least one lens L1ap with positive refractive power, and the 1b lens group G1b may have a lens L1bm with negative refractive power and with a concave surface facing the object side.

[0010] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (2) 0.10 < d12W / LTW < 0.30 d12W: The distance on the optical axis between the surface of the first lens group G1 closest to the image side and the surface of the second lens group G2 closest to the object side at the wide-angle end and when focusing at infinity LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end

[0011] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (3) 0.05 < d2MT / LTT < 0.35 d2MT: The distance on the optical axis between the surface of the second lens group G2 closest to the image side and the surface of the intermediate lens group GM closest to the object side at the telephoto end and when focusing at infinity LTT: The distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the telephoto end

[0012] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (4)4.50 < (LTW*SD1) / (Ymax^2) < 60.0 LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end SD1: Maximum effective light height of the first lens group G1 Ymax: Maximum image height

[0013] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (5) 0.01 < f1b / f1a < 4.50 f1b: focal length of the 1bth lens group G1b f1a: focal length of the 1ath lens group G1a

[0014] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (6) 0.25 < FnohT / Ymax < 1.40 FnohT: Height of aperture diaphragm when focused at infinity at telephoto end Ymax: Maximum image height

[0015] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (7) 0.05 < f1b / f1 < 5.70 (8)-10.0 < f1 / fW < -0.50 (9) 0.20 < f2 / fT < 1.30 (10) 0.10 < fMLT / fT < 9.50 (11)-50.0 < fL / fT < -0.01 f1b: focal length of the 1bth lens group G1b f1: focal length of the first lens group G1 when focusing at infinity fW: Focal length of the entire lens system at the wide-angle end, when focused on infinity f2: focal length of the second lens group G2 fT: focal length of the entire lens system at the telephoto end, when focused on infinity fMLT: composite focal length from the middle lens group GM to the final lens group GL at the telephoto end fL: focal length of the final lens group GL

[0016] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (12)55.0 < vd2p (13)0.005 < ΔPgF2p (14)60.0 < vdM2p (15)0.015 < ΔPgFM2p vd2p: the Abbe number of the positive lens Lvd2p having the largest Abbe number in the second lens group G2 ΔPgF2P: ΔPgF of the positive lens Lvd2p in the second lens group G2 Where: ΔPgF: Anomalous dispersion between the g and F lines, expressed by the following formula: ΔPgF = PgF - 0.64833 + 0.00180νd PgF=(ng-nF) / (nF-nC): Partial dispersion ratio between g and F lines ng: Refractive index for g-line (wavelength λ=435.84 nm) nF: Refractive index for F line (wavelength λ = 486.13 nm) nC: Refractive index for C line (wavelength λ=656.27 nm) vdMp: Abbe number of the positive lens LvdMp having the largest Abbe number in the intermediate lens group GM ΔPgFMP: ΔPgF of the positive lens LvdMp in the intermediate lens group GM

[0017] In a large aperture ratio zoom lens embodying the present invention, the following conditional expression may be satisfied. (16) 1.10 < βLW < 3.00 βLW: The lateral magnification of the final lens group GL at the wide-angle end and when focused on infinity Effect of the Invention

[0018] A large aperture ratio zoom lens embodying the present invention can accommodate a large image sensor, suppress changes in the angle of view during focusing, and achieve a large aperture ratio while suppressing an increase in the size of the optical system. [Brief description of the drawings]

[0019] [Figure 1] 1 is a lens configuration diagram of a large aperture ratio zoom lens according to a first embodiment of the present invention. [Diagram 2] 4A to 4C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 1 at the wide-angle end and at a shooting distance of infinity. [Diagram 3]4A to 4C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 1 at the telephoto end and at a shooting distance of infinity. [Figure 4] 4A to 4C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 1 at the wide-angle end and at a shooting distance of infinity. [Diagram 5] 4A to 4C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 1 at the telephoto end and at a shooting distance of infinity. [Figure 6] FIG. 4 is a lens configuration diagram of a large aperture ratio zoom lens according to a second embodiment of the present invention. [Figure 7] 11A to 11C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 2 at the wide-angle end and at a shooting distance of infinity. [Figure 8] 11A to 11C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 2 at the telephoto end and at a shooting distance of infinity. [Figure 9] 6A to 6C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 2 at the wide-angle end and at a shooting distance of infinity. [Figure 10] 6A to 6C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 2 at the telephoto end and at a shooting distance of infinity. [Figure 11] FIG. 11 is a lens configuration diagram of a large aperture ratio zoom lens according to a third embodiment of the present invention. [Figure 12] 11A to 11C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 3 at the wide-angle end and at a shooting distance of infinity. [Figure 13] 11A to 11C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 3 at the telephoto end and at a shooting distance of infinity. [Figure 14] 11A to 11C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 3 at the wide-angle end and at a shooting distance of infinity. [Figure 15] 11A to 11C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 3 at the telephoto end and at a shooting distance of infinity. [Figure 16] FIG. 11 is a lens configuration diagram of a large aperture ratio zoom lens according to a fourth embodiment of the present invention. [Figure 17] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 4 at the wide-angle end and at a shooting distance of infinity. [Figure 18] 11A to 11C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 4 at the telephoto end and at a shooting distance of infinity. [Figure 19] 11A to 11C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 4 at the wide-angle end and at a shooting distance of infinity. [Figure 20] 11A to 11C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 4 at the telephoto end and at a shooting distance of infinity. [Figure 21] FIG. 11 is a lens configuration diagram of a large aperture ratio zoom lens according to a fifth embodiment of the present invention. [Figure 22] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 5 at the wide-angle end and at a shooting distance of infinity. [Diagram 23] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 5 at the telephoto end and at a shooting distance of infinity. [Figure 24] 13A to 13C are lateral aberration diagrams of the large aperture ratio zoom lens of Example 5 at the wide-angle end and at a shooting distance of infinity. [Diagram 25] 13A to 13C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 5 at the telephoto end and at a shooting distance of infinity. [Figure 26] FIG. 11 is a lens configuration diagram of a large aperture ratio zoom lens according to a sixth embodiment of the present invention. [Figure 27] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 6 at the wide-angle end and at a shooting distance of infinity. [Figure 28] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 6 at the telephoto end and at a shooting distance of infinity. [Figure 29] 13A to 13C are lateral aberration diagrams of the large aperture ratio zoom lens of Example 6 at the wide-angle end and at a shooting distance of infinity. [Diagram 30] 13A to 13C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 6 at the telephoto end and at a shooting distance of infinity. [Diagram 31] FIG. 13 is a lens configuration diagram of a large aperture ratio zoom lens according to Example 7 of the present invention. [Diagram 32] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 7 at the wide-angle end and at a shooting distance of infinity. [Diagram 33] 13A to 13C are longitudinal aberration diagrams of the large aperture ratio zoom lens of Example 7 at the telephoto end and at a shooting distance of infinity. [Diagram 34]13A to 13C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 7 at the wide-angle end and at a shooting distance of infinity. [Diagram 35] 13A to 13C are diagrams illustrating lateral aberration of the large aperture ratio zoom lens of Example 7 at the telephoto end and at a shooting distance of infinity. [Diagram 36] FIG. 11 is a schematic diagram of Δ1ab related to conditional formula (1). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] As can be seen from the lens construction diagrams shown in Figures 1, 6, 11, 16, 21, 26 and 31, the large aperture ratio zoom lens of the present invention comprises, in order from the object side, a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM having multiple lens groups, and a final lens group GL with negative refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the intermediate lens group GM changes, and the distance between the intermediate lens group GM and the final lens group GL changes. The intermediate lens group GM comprises, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power; the distance between the M1 lens group GM1 and the M2 lens group GM2 changes when zooming from the wide-angle end to the telephoto end; the aperture stop is located adjacent to the intermediate lens group GM or within the intermediate lens group GM; and the first lens group G1 comprises, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power; and when focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side.

[0021] The reason for adopting the above-mentioned configuration will be described below. In order to perform good aberration correction for the entire system, it is necessary to arrange the lenses appropriately. By adopting the above-mentioned lens configuration from the object side, it is possible to prevent the entire lens system, including zooming, from becoming large.

[0022] Furthermore, the lens arrangement and zooming configuration from the first lens group G1 to the intermediate lens group GM achieve both a large aperture ratio and aberration correction, and the final lens group GL, which has negative refractive power, serves to enlarge the image circle to accommodate large image sensors.

[0023] Furthermore, at the wide-angle end in particular, because of the lens configuration with a retrofocus type power arrangement, the overall optical length, which is the distance from the lens surface closest to the object to the image plane, tends to be long; however, the final lens group GL has negative refractive power, and thus serves to shorten the overall optical length.

[0024] Furthermore, when focusing from infinity to a close distance, by making all lens groups other than the 1b lens group G1b fixed relative to the image plane, the focusing mechanism can be simplified and the product can be made lighter accordingly.

[0025] Furthermore, the 1bth lens group G1b is disposed at a position away from the aperture stop, and a configuration can be adopted in which the change in height of the chief ray during focusing is small, thereby making it possible to reduce the change in the angle of view during focusing.

[0026] Furthermore, by keeping the final lens group GL fixed relative to the image plane during zooming from the wide-angle end to the telephoto end, the zooming mechanism can be simplified, factors that may lead to manufacturing errors can be reduced, and dust can be prevented from entering the lens barrel.

[0027] In addition, the 1a lens group G1a has at least one lens L1ap having positive refractive power, which enables good correction of chromatic aberration of off-axis light, and the 1b lens group G1b has a negative lens L1bm with a concave surface facing the object side, which enables good correction of aberration during focusing.

[0028] It is desirable for the large aperture ratio zoom lens of the present invention to satisfy the following conditional expression. (1) 0.10 < Δ1ab / SD1 < 0.90 Δ1ab: the distance parallel to the optical axis between the position of maximum effective ray height on the surface closest to the image side of the 1a lens group G1a and the position of maximum effective ray height on the surface closest to the object side of the 1b lens group G1b when focusing at infinity SD1: Maximum effective light height of the first lens group G1

[0029] Conditional formula (1) stipulates the desirable conditions for preventing the entire lens system from becoming large and for focusing. See FIG. 36 for Δ1ab. If the upper limit of conditional formula (1) is exceeded and the lens spacing between group 1a G1a and group 1b G1b becomes large, it becomes difficult to prevent the overall length of the entire lens system from becoming large. If the lower limit of conditional formula (1) is exceeded and the lens spacing between group 1a G1a and group 1b G1b becomes small, this is not desirable because the spacing required for focusing is too small.

[0030] It is more preferable to set the lower limit of the above-mentioned conditional expression (1) to 0.15 and the upper limit to 0.40.Furthermore, by setting the lower limit to 0.20 and the upper limit to 0.35, the above-mentioned effect can be more reliably achieved.

[0031] (2) 0.10 < d12W / LTW < 0.30 d12W: The distance on the optical axis between the surface of the first lens group G1 closest to the image side and the surface of the second lens group G2 closest to the object side at the wide-angle end and when focusing at infinity LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end

[0032] Conditional formula (2) specifies the preferable conditions for preventing the entire lens system from becoming large and for zooming. If the upper limit of conditional formula (2) is exceeded and the distance between the first lens group G1 and the second lens group G2 becomes large, it becomes difficult to prevent the overall length of the entire lens system from becoming large. If the lower limit of conditional formula (2) is exceeded and the distance between the first lens group G1 and the second lens group G2 becomes small, it becomes undesirable because the distance required to ensure the necessary zoom ratio becomes small. Furthermore, to ensure a necessary zoom ratio, the refractive power of each group must be strengthened, which makes it difficult to correct aberrations, which is undesirable.

[0033] It is more preferable to set the lower limit of the above-mentioned conditional expression (2) to 0.14 and the upper limit to 0.25.Furthermore, by setting the lower limit to 0.16 and the upper limit to 0.23, the above-mentioned effect can be more reliably achieved.

[0034] (3) 0.05 < d2MT / LTT < 0.35 d2MT: The distance on the optical axis between the surface of the second lens group G2 closest to the image side and the surface of the intermediate lens group GM closest to the object side at the telephoto end and when focusing on infinity LTT: The distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the telephoto end

[0035] Conditional formula (3) specifies the preferable conditions for preventing the entire lens system from becoming large and for zooming. If the upper limit of conditional formula (3) is exceeded and the distance between the second lens group G2 and the intermediate lens group GM becomes large, it becomes difficult to prevent the overall length of the entire lens system from becoming large. If the lower limit of conditional formula (3) is exceeded and the distance between the second lens group G2 and the intermediate lens group GM becomes small, the distance required to ensure the necessary zoom ratio becomes small, which is not preferable. Furthermore, to ensure a certain zoom ratio, the refractive power of each group must be strengthened, which makes it difficult to correct aberrations, which is not preferable.

[0036] It is more preferable to set the lower limit of the above-mentioned conditional expression (3) to 0.10 and the upper limit to 0.30.Furthermore, by setting the lower limit to 0.14 and the upper limit to 0.26, the above-mentioned effect can be more reliably achieved.

[0037] (4)4.50 < (LTW*SD1) / (Ymax^2) < 60.0 LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end SD1: Maximum effective light height of the first lens group G1 Ymax: Maximum image height

[0038] Conditional formula (4) specifies the preferable conditions for preventing the entire lens system from becoming large and for the arrangement of the moving groups. If the upper limit of conditional formula (4) is exceeded and the product of the lens diameter and the optical total length of the first lens group G1 becomes large, the entire lens system becomes large and it becomes difficult to reduce the product weight. If the lower limit of conditional formula (4) is exceeded and the product of the lens diameter and the optical total length of the first lens group G1 becomes small, it becomes difficult to ensure the lens diameter required for a large aperture ratio and the spacing required to ensure the required zoom ratio becomes small, which is not preferable. Furthermore, to ensure a large aperture ratio or zoom ratio, the refractive power of each group must be strengthened, which is not preferable because it becomes difficult to correct aberrations.

[0039] It is more preferable to set the lower limit of the above-mentioned conditional expression (4) to 10.0 and the upper limit to 30.0.Furthermore, by setting the lower limit to 13.0 and the upper limit to 25.0, the above-mentioned effect can be more reliably achieved.

[0040] (5) 0.01 < f1b / f1a < 4.50 f1b: focal length of the 1bth lens group G1b f1a: focal length of the 1ath lens group G1a

[0041] Conditional formula (5) defines a preferable condition for focusing. If the upper limit of conditional formula (5) is exceeded and the refractive power of the 1b lens group G1b becomes weak, the amount of movement required for focusing becomes long and the overall lens system becomes large, which is not preferable. If the lower limit of conditional formula (5) is exceeded and the refractive power of the 1b lens group G1b becomes strong, it becomes difficult to correct aberrations during focusing, which is not preferable.

[0042] It is more preferable to set the lower limit of the above-mentioned conditional expression (5) to 0.05 and the upper limit to 3.50.Furthermore, by setting the lower limit to 0.10 and the upper limit to 1.00, the above-mentioned effect can be more reliably achieved.

[0043] (6) 0.25 < FnohT / Ymax < 1.40 FnohT: F-number ray height on the aperture stop surface when focused at infinity at the telephoto end

[0044] Conditional formula (6) specifies a preferable condition for the product diameter. If the upper limit of conditional formula (6) is exceeded and the height of the F-number ray on the aperture stop surface becomes large, the aperture stop itself becomes large, which is undesirable, and the product diameter becomes large. If the lower limit of conditional formula (6) is exceeded and the height of the F-number ray on the aperture stop surface becomes small, the refractive power of the second lens group G2 in particular becomes strong, which is undesirable, as it becomes difficult to correct various aberrations including spherical aberration.

[0045] It is more preferable to set the lower limit of the above-mentioned conditional expression (6) to 0.50 and the upper limit to 1.10.Furthermore, by setting the lower limit to 0.65 and the upper limit to 1.00, the above-mentioned effect can be more reliably achieved.

[0046] (7) 0.05 < f1b / f1 < 5.70 (8)-10.0 < f1 / fW < -0.50 (9) 0.20 < f2 / fT < 1.30 (10) 0.10 < fMLT / fT < 9.50 (11)-50.0 < fL / fT < -0.01 f1b: focal length of the 1bth lens group G1b f1: focal length of the first lens group G1 when focusing at infinity fW: Focal length of the entire lens system at the wide-angle end, when focused on infinity f2: focal length of the second lens group G2 fT: focal length of the entire lens system at the telephoto end, when focused on infinity fMLT: Telephoto end, composite focal length from the middle lens group GM to the final lens group GL fL: focal length of the final lens group GL

[0047] Conditional formula (7) specifies the preferable condition for the appropriate power arrangement of the 1b lens group and the 1 lens group. If the upper limit of conditional formula (7) is exceeded and the refractive power of the 1b lens group G1b becomes weak, the amount of movement required for focusing becomes long and the overall lens system becomes large, which is not preferable. If the lower limit of conditional formula (7) is exceeded and the refractive power of the 1b lens group G1b becomes strong, it becomes difficult to correct aberrations during focusing, which is not preferable.

[0048] It is more preferable to set the lower limit of the above-mentioned conditional expression (7) to 0.50 and the upper limit to 3.50.Furthermore, by setting the lower limit to 1.00 and the upper limit to 1.60, the above-mentioned effect can be more reliably achieved.

[0049] Conditional formula (8) specifies a preferable condition for the appropriate power arrangement of the first lens group G1. If the refractive power of the first lens group G1 exceeds the upper limit of conditional formula (8) and becomes strong, the F-number ray will be strongly raised, which is undesirable because it will result in an increase in the size of the second lens group G2 at the telephoto end, and in order to make the lens compact, the refractive power of the second lens group G2 will be strengthened, making it difficult to correct various aberrations including spherical aberration. If the refractive power of the first lens group G1 exceeds the lower limit of conditional formula (8), the effect similar to that of a retrofocus type will be weakened, making it difficult to lower the effective ray height of the first lens group G1 and to correct aberrations of off-axis rays at the same time, and in particular, making it difficult to correct astigmatism, which is undesirable. In addition, when trying to reduce the product diameter, off-axis marginal rays in the first lens group G1 will be cut, which is undesirable because vignetting will become large.

[0050] It is more preferable to set the lower limit of the above-mentioned conditional expression (8) to -4.00 and the upper limit to -0.80.Furthermore, by setting the lower limit to -2.20 and the upper limit to -1.10, the above-mentioned effect can be more reliably achieved.

[0051] Conditional formula (9) prescribes a preferable condition for the appropriate power arrangement of the second lens group G2. If the upper limit of conditional formula (9) is exceeded and the refractive power of the second lens group G2 becomes weak, the amount of movement during zooming increases, the lens diameter of the intermediate lens group GM becomes large, and it becomes difficult to reduce the size of the entire lens system, which is undesirable. If the refractive power of the second lens group G2 becomes strong and the lower limit of conditional formula (9) is exceeded, it becomes difficult to correct various aberrations including spherical aberration, making it difficult to achieve both a large aperture ratio and good aberration correction.

[0052] It is more preferable to set the lower limit of the above-mentioned conditional expression (9) to 0.30 and the upper limit to 1.10.Furthermore, by setting the lower limit to 0.40 and the upper limit to 0.90, the above-mentioned effect can be more reliably achieved.

[0053] Conditional formula (10) specifies the preferable condition for the refractive power from the intermediate lens group GM to the final lens group GL to have a positive refractive power in order to achieve a large aperture ratio and to reduce the size of the entire lens system. If the refractive power from the intermediate lens group GM to the final lens group GL weakens beyond the upper limit of conditional formula (10), it becomes difficult to lower the height of the on-axis marginal ray, which makes it difficult to achieve a large aperture ratio, which is undesirable. If the refractive power from the intermediate lens group GM to the final lens group GL strengthens beyond the lower limit of conditional formula (10), the off-axis ray is lowered, which narrows the image circle and makes it impossible to accommodate a large image sensor, which is undesirable.

[0054] It is more preferable to set the lower limit of the above-mentioned conditional expression (10) to 0.70 and the upper limit to 6.00.Furthermore, by setting the lower limit to 1.20 and the upper limit to 3.00, the above-mentioned effect can be more reliably achieved.

[0055] Conditional formula (11) specifies a preferable condition regarding the refractive power of the final lens group GL. If the refractive power of the final lens group GL becomes strong beyond the upper limit of conditional formula (11), the lateral magnification of the group will become strong. This is undesirable because it will increase the aberration magnification effect and make it difficult to perform good aberration correction. It is also undesirable because it will tend to shorten the back focus and make it difficult to ensure the flange back. If the refractive power of the final lens group GL becomes weak beyond the lower limit of conditional formula (11), the lateral magnification of the group will become weak. This is undesirable because the off-axis light rays will decrease and the image circle will narrow, making it impossible to accommodate a large image sensor. It is also undesirable because it will make it difficult to shorten the overall lens length due to the weakening of the telephoto type effect.

[0056] It is more preferable to set the lower limit of the above-mentioned conditional expression (11) to -5.00 and the upper limit to -0.15. Furthermore, by setting the lower limit to -1.50 and the upper limit to -0.30, the above-mentioned effect can be more reliably achieved.

[0057] (12)55.0 < vd2p (13)0.005 < ΔPgF2p (14)60.0 < vdM2p (15)0.015 < ΔPgFM2p vd2p: the Abbe number of the positive lens Lvd2p having the largest Abbe number in the second lens group G2 ΔPgF2P: ΔPgF of the positive lens Lvd2p in the second lens group G2 Where: ΔPgF is the anomalous dispersion between the g and F lines and is expressed by the following formula. ΔPgF = PgF - 0.64833 + 0.00180νd PgF=(ng-nF) / (nF-nC): Partial dispersion ratio between g and F lines ng: Refractive index for g-line (wavelength λ=435.84 nm) nF: Refractive index for F line (wavelength λ = 486.13 nm) nC: Refractive index for C line (wavelength λ=656.27 nm) vdMp: Abbe number of the positive lens LvdMp having the largest Abbe number in the intermediate lens group GM ΔPgFMP: ΔPgF of the positive lens LvdMp in the intermediate lens group GM

[0058] Conditional expression (12) specifies a preferable condition for chromatic aberration correction with respect to the Abbe number of the positive lens Lvd2p having the largest Abbe number in the second lens group G2. If the Abbe number becomes small beyond the lower limit of conditional expression (12), it becomes difficult to correct axial chromatic aberration over the entire zoom range, which is not preferable.

[0059] It is more preferable to set the lower limit of the above-mentioned conditional expression (12) to 60.0. Furthermore, by setting the lower limit to 65.0, the above-mentioned effect can be ensured. In addition, as for the glass material options, those with a large Abbe number tend to have a low refractive index, and a low refractive index makes it difficult to correct chromatic spherical aberration, so by setting the upper limit to 88.0, the above-mentioned effect can be ensured.

[0060] Conditional formula (13) prescribes preferable conditions for chromatic aberration correction with respect to the anomalous dispersion ΔPgF number of the positive lens Lvd2p having the largest Abbe number in the second lens group G2. If the anomalous dispersion becomes small by exceeding the lower limit of conditional formula (13), the secondary spectrum of axial chromatic aberration throughout the entire zoom range will be undercorrected, and the secondary spectrum of lateral chromatic aberration on the telephoto side will also be undercorrected, which is not preferable.

[0061] It is more preferable to set the lower limit of the above-mentioned conditional expression (13) to 0.015. Furthermore, by setting the lower limit to 0.018, the above-mentioned effect can be ensured. In addition, glass materials with a large ΔPgF tend to have a low refractive index, and a low refractive index makes it difficult to correct chromatic spherical aberration, so by setting the upper limit to 0.045, the above-mentioned effect can be ensured.

[0062] Conditional expression (14) defines a preferable condition for correcting chromatic aberration with respect to the Abbe number of the positive lens LvdMp having the largest Abbe number in the intermediate lens group GM. If the Abbe number becomes small beyond the lower limit of conditional expression (14), it becomes difficult to correct axial chromatic aberration over the entire zoom range, which is not preferable.

[0063] It is more preferable to set the lower limit of the above-mentioned conditional expression (14) to 65.0.Furthermore, by setting the lower limit to 70.0, the above-mentioned effect can be more reliably achieved.

[0064] Conditional formula (15) prescribes a preferable condition for chromatic aberration correction with respect to the anomalous dispersion ΔPgF number of the positive lens LvdMp having the largest Abbe number in the intermediate lens group GM. If the anomalous dispersion becomes small by exceeding the lower limit of conditional formula (15), the axial chromatic aberration and the secondary spectrum of the lateral chromatic aberration will be undercorrected throughout the entire zoom range, which is not preferable.

[0065] (16) 1.10 < βLW < 3.00 βLW: The lateral magnification of the final lens group GL at the wide-angle end and when focused on infinity

[0066] Conditional formula (16) specifies a preferable condition regarding the lateral magnification of the final lens group GL. If the lateral magnification of the final lens group GL increases beyond the upper limit of conditional formula (16), the magnification of aberrations will increase. In addition, in order to achieve a large aperture ratio, it is necessary to further increase the aperture ratio of the lens system closer to the object than the final lens group GL, which is undesirable because it becomes difficult to achieve both good aberration correction and compactness of the entire lens system. If the lateral magnification of the final lens group GL decreases beyond the lower limit of conditional formula (16), off-axis light rays will decrease, narrowing the image circle and making it impossible to accommodate a large image sensor, which is undesirable. In addition, the effect of shortening the total optical length will be weakened, making it difficult to compact the entire lens system.

[0067] It is more preferable to set the lower limit of the above-mentioned conditional expression (16) to 1.20 and the upper limit to 2.80.Furthermore, by setting the lower limit to 1.30 and the upper limit to 2.50, the above-mentioned effect can be more reliably achieved.

[0068] Next, a lens configuration of an embodiment of a large aperture ratio zoom lens according to the present invention will be described below. Note that in the following description, the lens configuration will be described in order from the object side to the image side. EXAMPLES

[0069] 1 is a lens configuration diagram of the first embodiment of the present invention. In order from the object side, the first to fourth lenses are the first lens group G1, the fifth to ninth lenses are the second lens group G2, the tenth to fifteenth lenses are the intermediate lens group GM, and the sixteenth to eighteenth lenses are the final lens group GL. Within the first lens group G1, the first to second lenses are the 1a lens group G1a, the third to fourth lenses are the 1b lens group G1b, and within the intermediate lens group GM, the tenth to fourteenth lenses are the M1 lens group GM1, and the fifteenth lens is the M2 lens group GM2.

[0070] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL increases. The intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 increases and then decreases, the final lens group GL is fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0071] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0072] The 1ath lens group G1a is composed of a concave meniscus lens whose object-side surface is aspheric and whose convex surface faces the object side, and a convex meniscus lens L1ap whose convex surface faces the object side. The 1bth lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens whose convex surface faces the object side. The second lens group G2 is composed of a convex meniscus lens whose convex surface faces the object side, a biconvex lens, a cemented lens of a biconvex lens and a biconcave lens with negative refractive power, and a biconvex lens whose both surfaces are aspheric. The M1th lens group GM1 is composed of a biconcave lens, a biconcave lens and a biconvex lens with negative refractive power. M1 lens group GM1 is a convex meniscus lens with a convex surface facing the object side and a biconvex lens with positive refractive power, M2 lens group GM2 is a convex meniscus lens with a convex surface facing the object side and a biconvex lens with positive refractive power, M3 lens group GM3 is a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side, and the final lens group GL is a convex meniscus lens with a convex surface facing the object side, a concave meniscus lens with a convex surface facing the object side and a concave meniscus lens with an aspheric surface on the image side and a convex surface facing the object side, and in the above conditional formula, Lvd2p is the seventh lens from the object side, and LvdMp is the fourteenth lens from the object side. EXAMPLES

[0073] 6 is a lens configuration diagram of Example 2 of the present invention. In order from the object side, the first to fifth lenses are the first lens group G1, the sixth to ninth lenses are the second lens group G2, the tenth to sixteenth lenses are the middle lens group GM, and the seventeenth to twentieth lenses are the final lens group GL. Within the first lens group G1, the first to third lenses are the 1a lens group G1a, the fourth to fifth lenses are the 1b lens group G1b, and within the middle lens group GM, the tenth to twelfth lenses are the M1 lens group GM1, and the thirteenth to sixteenth lenses are the M2 lens group GM2.

[0074] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL increases. The intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the final lens group GL is fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0075] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0076] The 1ath lens group G1a is composed of a double-sided aspheric concave meniscus lens with a convex surface facing the object side, a cemented lens with positive refractive power consisting of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens L1ap with a convex surface facing the object side. The 1bth lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens with a biconvex surface facing the object side, a convex meniscus lens with a convex surface facing both object sides, and a biconvex lens. The M1th lens group GM1 is composed of a concave meniscus lens with a convex surface facing the object side, a biconcave lens and a biconvex lens. The M1 lens group GM1 consists of a cemented lens having positive refractive power made of a convex meniscus lens with a concave surface facing the object side and a concave meniscus lens with a concave surface facing the object side, a biconvex lens, and a biconvex lens with aspherical surfaces on both sides. The final lens group GL consists of a concave meniscus lens with a convex surface facing the object side, a cemented lens having negative refractive power made of a convex meniscus lens with a convex surface facing the object side and a concave meniscus lens with a convex surface facing the object side, and a convex meniscus lens with a convex surface facing the object side. In the above conditional expressions, Lvd2p is the 9th lens from the object side, and LvdMp is the 15th lens from the object side. EXAMPLES

[0077] 11 is a lens configuration diagram of Example 3 of the present invention. In order from the object side, the first to fifth lenses are the first lens group G1, the sixth to ninth lenses are the second lens group G2, the tenth to sixteenth lenses are the intermediate lens group GM, and the seventeenth to twentieth lenses are the final lens group GL. Within the first lens group G1, the first to third lenses are the 1a lens group G1a, the fourth to fifth lenses are the 1b lens group G1b, and within the intermediate lens group GM, the tenth to twelfth lenses are the M1 lens group GM1, and the thirteenth to sixteenth lenses are the M2 lens group GM2.

[0078] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL increases. The intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the final lens group GL is fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0079] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0080] The 1ath lens group G1a is composed of a double-sided aspheric concave meniscus lens with a convex surface facing the object side, a cemented lens with positive refractive power consisting of a concave meniscus lens with a convex surface facing the object side and a convex meniscus lens L1ap with a convex surface facing the object side. The 1bth lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a biconvex lens with a biconvex surface facing the object side, a convex meniscus lens with a convex surface facing the object side, a concave meniscus lens with a convex surface facing both object sides, and a biconvex lens. The M1th lens group GM1 is composed of a double-sided aspheric concave meniscus lens with a convex surface facing the object side. The M1 lens group GM1 consists of a concave meniscus lens with a convex surface facing the object side, a cemented lens with positive refractive power made of a biconvex lens and a biconcave lens and a biconvex lens, and a biconvex lens with aspheric surfaces on both sides. The final lens group GL consists of a concave meniscus lens with a convex surface facing the object side, a cemented lens with negative refractive power made of a biconvex lens and a biconcave lens, and a convex meniscus lens with a convex surface facing the object side. In the above conditional expressions, Lvd2p is the 9th lens from the object side, and LvdMp is the 15th lens from the object side. EXAMPLES

[0081] 16 is a lens configuration diagram of the fourth embodiment of the present invention. In order from the object side, the first to fifth lenses are the first lens group G1, the sixth to ninth lenses are the second lens group G2, the tenth to sixteenth lenses are the intermediate lens group GM, and the seventeenth to twentieth lenses are the final lens group GL. In the first lens group G1, the first to third lenses are the 1a lens group G1a, the fourth to fifth lenses are the 1b lens group G1b, and in the intermediate lens group GM, the tenth to twelfth lenses are the M1 lens group GM1, and the thirteenth to sixteenth lenses are the M2 lens group GM2.

[0082] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL decreases and then increases, and the intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the first lens group G1 and the final lens group GL are fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0083] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0084] The 1a lens group G1a is composed of a double-sided aspheric concave meniscus lens with a convex surface facing the object side, and a cemented lens with positive refractive power of a concave meniscus lens with a convex surface facing the object side and a biconvex lens L1ap. The 1b lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a convex meniscus lens with a convex surface facing the object side, a biconvex lens with a biconcave surface facing the object side, and a biconcave lens and a biconvex lens. The M1 lens group GM1 is composed of a concave meniscus lens with a convex surface facing the object side. M1 lens group GM1 consists of a biconvex lens, a cemented lens made of a biconcave lens and a biconvex lens with negative refractive power, and a biconvex lens with aspherical surfaces on both sides. Final lens group GL consists of a concave meniscus lens with its convex surface facing the object side, a cemented lens made of a biconvex lens and a biconcave lens with negative refractive power, and a convex meniscus lens with its convex surface facing the object side. In the above conditional expressions, Lvd2p is the 9th lens from the object side, and LvdMp is the 15th lens from the object side. EXAMPLES

[0085] 21 is a lens configuration diagram of the fifth embodiment of the present invention. In order from the object side, the first to fifth lenses are the first lens group G1, the sixth to ninth lenses are the second lens group G2, the tenth to sixteenth lenses are the intermediate lens group GM, and the seventeenth to twentieth lenses are the final lens group GL. Within the first lens group G1, the first to third lenses are the 1a lens group G1a, the fourth to fifth lenses are the 1b lens group G1b, and within the intermediate lens group GM, the tenth to twelfth lenses are the M1 lens group GM1, and the thirteenth to sixteenth lenses are the M2 lens group GM2.

[0086] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL decreases and then increases, and the intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the first lens group G1 and the final lens group GL are fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0087] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0088] The 1ath lens group G1a consists of a double-sided aspherical concave meniscus lens with its convex surface facing the object side, and a cemented lens with positive refractive power consisting of a biconcave lens and a biconvex lens L1ap. The 1bth lens group G1b consists of a cemented lens consisting of a biconcave lens L1bm and a convex meniscus lens with its convex surface facing the object side. The second lens group G2 consists of a convex meniscus lens with its convex surface facing the object side, a biconvex lens with biconcave surfaces aspherical on both sides, a biconcave lens, and a biconvex lens. The M1th lens group GM1 consists of a concave meniscus lens with its convex surface facing the object side, a biconcave lens, and a convex lens The M1 lens group GM1 consists of a biconvex lens, a cemented lens made of a biconcave lens and a biconvex lens with negative refractive power, and a biconvex lens with aspherical surfaces on both sides. The final lens group GL consists of a concave meniscus lens with its convex surface facing the object side, a concave meniscus lens with its convex surface facing the object side, and a cemented lens made of a biconvex lens and a biconcave lens with positive refractive power. In the above conditional expressions, Lvd2p is the 9th lens from the object side, and LvdMp is the 15th lens from the object side. EXAMPLES

[0089] 26 is a lens configuration diagram of Example 6 of the present invention. In order from the object side, the first to fifth lenses are the first lens group G1, the sixth to ninth lenses are the second lens group G2, the tenth to sixteenth lenses are the intermediate lens group GM, and the seventeenth to twentieth lenses are the final lens group GL. Within the first lens group G1, the first to third lenses are the 1a lens group G1a, the fourth to fifth lenses are the 1b lens group G1b, and within the intermediate lens group GM, the tenth to twelfth lenses are the M1 lens group GM1, and the thirteenth to sixteenth lenses are the M2 lens group GM2.

[0090] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL decreases and then increases, and the intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the first lens group G1 and the final lens group GL are fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0091] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0092] The 1a lens group G1a is composed of a double-sided aspheric concave meniscus lens with a convex surface facing the object side, and a cemented lens with positive refractive power of a concave meniscus lens with a convex surface facing the object side and a biconvex lens L1ap. The 1b lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens with a convex surface facing the object side. The second lens group G2 is composed of a convex meniscus lens with a convex surface facing the object side, a biconvex lens with a biconcave surface facing the object side, and a biconcave lens. The M1 lens group GM1 is composed of a concave meniscus lens with a convex surface facing the object side, and a biconcave lens. M1 lens group GM1 consists of a biconvex lens, a cemented lens consisting of a biconcave lens and a biconvex lens with negative refractive power, and a biconvex lens with aspherical surfaces on both sides. Final lens group GL consists of a concave meniscus lens with a convex surface facing the object side, a cemented lens consisting of a biconvex lens and a biconcave lens with negative refractive power, and a convex meniscus lens with a convex surface facing the object side. In the above conditional expressions, Lvd2p is the 9th lens from the object side, and LvdMp is the 15th lens from the object side. EXAMPLES

[0093] 31 is a lens configuration diagram of Example 7 of the present invention. In order from the object side, the first to fourth lenses are the first lens group G1, the fifth to eighth lenses are the second lens group G2, the ninth to fifteenth lenses are the middle lens group GM, and the sixteenth to nineteenth lenses are the final lens group GL. Within the first lens group G1, the first to second lenses are the 1a lens group G1a, the third to fourth lenses are the 1b lens group G1b, and within the middle lens group GM, the ninth to eleventh lenses are the M1 lens group GM1, and the twelfth to fifteenth lenses are the M2 lens group GM2.

[0094] It consists of a first lens group G1 with negative refractive power, a second lens group G2 with positive refractive power, an intermediate lens group GM, and a final lens group GL also having negative refractive power, 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 decreases, the distance between the second lens group G2 and the intermediate lens group GM increases, and the distance between the intermediate lens group GM and the final lens group GL decreases and then increases, and the intermediate lens group GM has, from the object side, an M1 lens group GM1 with negative refractive power and an M2 lens group GM2 with positive refractive power, and when zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 decreases, the first lens group G1 and the final lens group GL are fixed with respect to the image plane, and the aperture diaphragm is adjacent to the object side of the intermediate lens group GM and moves as a unit during zooming.

[0095] The first lens group G1 consists of, from the object side, a 1a lens group G1a with negative refractive power and a 1b lens group G1b with negative refractive power. When focusing from infinity to a close distance, the 1b lens group G1b moves toward the object side, and all lens groups other than the 1b lens group G1b are fixed with respect to the image plane.

[0096] The 1ath lens group G1a is composed of a concave meniscus lens which is aspheric on both sides and has a convex surface facing the object side, and a convex meniscus lens which has a concave surface facing the object side. The 1bth lens group G1b is composed of a cemented lens of a biconcave lens L1bm and a convex meniscus lens which has a convex surface facing the object side. The second lens group G2 is composed of a convex meniscus lens which has a convex surface facing the object side, a biconvex lens which is aspheric on both sides, a biconvex lens, a biconcave lens, and a biconvex lens. The M1th lens group GM1 is composed of a biconcave lens, and a cemented lens of a biconcave lens and a biconvex lens with negative refractive power. The M2th lens group GM Reference numeral 2 consists of a convex meniscus lens with its concave surface facing the object side, a cemented lens consisting of a biconcave lens and a biconvex lens with negative refractive power, and a biconvex lens with aspherical surfaces on both sides. The final lens group GL consists of a concave meniscus lens with its convex surface facing the object side, a concave meniscus lens with its convex surface facing the object side, and a cemented lens consisting of a convex meniscus lens with its convex surface facing the object side and a concave meniscus lens with its convex surface facing the object side, with positive refractive power. In the above conditional expressions, Lvd2p is the eighth lens from the object side, and LvdMp is the fourteenth lens from the object side.

[0097] Specific numerical data for each of the embodiments of the imaging optical system of the present invention described above will be shown below.

[0098] 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), vd is the Abbe number for the d line, Pg_F is the partial dispersion ratio, and SD is the effective ray height.

[0099] An asterisk (*) next to a surface number indicates that the lens surface is aspheric, and BF stands for back focus.

[0100] 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).

[0101] [Aspheric Data] shows the values ​​of each coefficient that gives the aspheric shape of the lens surface marked with an * in [Surface Data]. The shape of the 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 A12 are the 4th to 12th order aspheric coefficients, respectively.

[0102] TIFF2024138617000002.tif19147

[0103] [Various Data] shows values ​​such as the zoom ratio and focal length at each focal length state.

[0104] [Variable Distance Data] shows the variable distance and BF values ​​for each focal length state.

[0105] [Lens Group Data] shows the surface number of each lens group closest to the object and the composite focal length of the entire group.

[0106] In addition, for all of the values ​​of the following specifications, the focal length f, radius of curvature r, lens surface spacing d, and other length units are given in millimeters (mm) unless otherwise specified; however, since the optical system provides equivalent optical performance with proportional magnification and proportional reduction, this is not limited to this.

[0107] Also shown is a list of values ​​corresponding to the conditional expressions in each of these embodiments.

[0108] In addition, in the aberration diagrams corresponding to the respective embodiments, d, g, and C represent the d-line, g-line, and C-line, respectively, and ΔS and ΔM represent the sagittal image surface and the meridional image surface, respectively.

[0109] Numerical Example 1 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 588.0929 2.6650 1.69350 53.19 0.5482 42.54 2 71.4453 9.3252 38.53 3 79.9358 6.3920 1.90366 31.34 0.5962 37.21 4 167.7056 (d4) 36.78 5 -69.4902 1.9416 1.74100 52.60 0.5443 32.02 6 170.8854 3.9106 1.84666 23.78 0.6191 32.21 7 700.8040 (d7) 32.21 8 127.6881 4.6002 1.80000 29.84 0.6016 34.89 9 342.6783 0.1500 34.81 10 77.0350 11.4189 1.75500 52.32 0.5474 36.46 11 -3951.3534 0.1500 36.22 12 54.3582 15.1847 1.55032 75.50 0.5398 33.70 13 -456.8497 2.0424 1.78880 28.43 0.6008 32.78 14 45.2931 4.7820 28.47 15* 64.8794 8.5312 1.59282 68.62 0.5440 28.47 16* -213.6137 (d16) 28.33 17 (Aperture) ∞ 2.7736 18.40 18 -300.4719 1.2320 1.51823 58.96 0.5440 19.07 19 62.4880 6.6549 18.53 20 -46.6004 1.1530 1.61293 36.96 0.5849 18.53 21 104.1886 6.9696 1.59282 68.62 0.5440 19.56 22 -68.5911 0.1500 19.89 23 73.7155 1.3008 1.61310 44.36 0.5604 20.31 24 29.7523 13.2177 1.55032 75.50 0.5398 19.91 25 -132.4436 (d25) 19.82 26* 69.5209 4.2998 1.92119 23.96 0.6201 19.20 27* 980.6996 (d27) 18.91 28 121.8751 2.5269 1.92286 20.88 0.6389 16.28 29 1487.4981 0.1500 15.93 30 74.5755 1.0771 1.67270 32.17 0.5961 15.69 31 36.8260 2.7542 15.24 32 95.7893 1.0264 1.85478 24.80 0.6122 15.25 33* 48.8022 (BF) 15.10 Image plane ∞ [Aspheric data] 1st page 15th page 16th page 26th page K 0.00000 0.00000 0.00000 0.00000 A4 2.69447E-07 -1.44194E-06 6.70226E-07 4.53843E-07 A6 3.47661E-11 -4.49077E-10 -4.43324E-10 -4.53240E-10 A8 1.38016E-14 -2.62726E-13 -2.00720E-14 3.61506E-13 A10 -6.12963E-18 A12 2.14341E-21 27th page 33rd page K 0.00000 0.00000 A4 5.13038E-07 2.50817E-06 A6 -6.15818E-10 1.32244E-09 A8 5.52476E-15 3.52512E-12 [Various data] Zoom ratio 1.96 Wide Angle Mid-Telephoto Focal length 50.79 71.11 99.56 F-number 1.86 1.86 1.87 Full angle of view 2ω 50.69 35.75 25.50 Image height Y 23.15 23.15 23.15 Lens total length 235.00 225.07 234.99 Aperture light height 18.40 19.33 19.53 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d4 23.5438 23.5438 23.5438 d7 45.4061 18.5684 2.0000 d16 1.5000 12.9913 39.3409 d25 5.3410 5.3544 1.5001 d27 1.5000 6.9067 10.9020 BF 41.3250 41.3250 41.3250 [Lens group data] Group starting plane focal length G1 1 -68.28 G2 8 55.45 GM1 18 -725.02 GM2 26 81.04 GL 28 -96.24 G1a 1 -483.54 G1b 5 -88.61

[0110] Numerical Example 2 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 120.8601 2.5013 1.69350 53.19 0.5482 40.00 2* 76.5610 7.2962 37.23 3 184.0705 2.3274 1.80834 40.92 0.5684 37.20 4 75.9040 6.8306 1.84666 23.78 0.6191 34.99 5 193.1341 (d5) 34.55 6 -93.9785 1.8900 1.81600 46.62 0.5567 30.88 7 144.1089 3.6210 1.92286 20.88 0.6389 30.12 8 426.0189 (d8) 30.00 9* 64.7454 10.7631 1.75500 52.32 0.5474 28.76 10* -175.5724 1.1390 ​​28.69 11 76.0641 3.6419 1.75500 52.32 0.5473 27.51 12 139.2263 2.5957 27.22 13 304.8858 1.6486 1.84666 23.78 0.6191 26.91 14 51.0192 1.6606 25.52 15 65.4896 8.3092 1.59282 68.62 0.5440 25.52 16 -226.0228 (d16) 25.39 17(Aperture) ∞ 1.8021 16.91 18 758.1017 1.0636 1.79450 45.39 0.5571 17.90 19 70.0893 6.3330 17.56 20 -39.7111 1.0415 1.56732 42.82 0.5730 17.56 21 137.6012 3.2531 1.92286 20.88 0.6389 18.70 22 -260.6742 (d22) 18.85 23 -6057.0330 8.4344 1.56908 71.34 0.5451 19.19 24 -35.6730 1.2380 1.77047 29.74 0.5950 19.47 25 -77.7499 0.1500 20.17 26 152.1779 6.6583 1.55032 75.50 0.5398 20.50 27 -72.0771 0.1500 20.51 28* 39.2421 8.6141 1.75500 52.32 0.5474 20.57 29* -301.2122 (d29) 19.96 30 251.8578 1.0000 1.77047 29.74 0.5950 18.65 31 31.7995 2.2426 17.44 32 47.8200 4.2629 1.92286 20.88 0.6389 17.47 33 188.1275 1.0942 1.85135 40.10 0.5694 17.24 34 34.5211 2.4293 16.62 35 66.1255 1.9490 2.05080 26.94 0.6050 16.69 36 80.4423 (BF) 16.65 image plane [Aspheric data] Side 1 Side 2 Side 9 Side 10 K 0.00000 1.85168 0.00000 0.00000 A4 -1.30381E-08 -7.04548E-07 -5.21344E-07 5.29039E-07 A6 4.61350E-10 3.19632E-10 -5.60006E-11 -7.14413E-11 A8 6.24378E-14 2.33450E-14 -8.53134E-15 A10 -6.16686E-17 1.23118E-17 3.06363E-17 A12 2.97461E-20 Page 28 Page 29 K 0.00000 0.00000 A4 -2.24534E-07 2.60678E-06 A6 2.30958E-10 -8.54356E-10 A8 -8.91350E-14 6.22486E-14 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 44.98 63.13 88.61 F-number 1.86 1.86 1.87 Full angle of view 2ω 56.51 39.84 28.50 Image height Y 23.15 23.15 23.15 Lens total length 220.01 207.02 208.95 Aperture Light Height 16.91 17.40 18.26 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 17.6602 17.6602 17.6602 d8 42.1845 18.5419 2.0000 d16 1.5000 15.5403 37.5998 d22 11.2946 6.7809 1.5010 d29 1.5000 2.6234 4.3176 BF 39.9292 39.9292 39.9292 [Lens group data] Group starting plane focal length G1 1 -74.56 G2 9 55.56 GM1 18 -53.39 GM2 23 27.87 GL 30 -41.37 G1a 1 -371.90 G1b 6 -98.50

[0111] Numerical Example 3 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 135.6465 2.5000 1.69350 53.19 0.5482 40.00 2* 87.4854 5.5314 37.76 3 182.9241 2.3610 1.80834 40.92 0.5684 37.74 4 76.4200 7.3465 1.84666 23.78 0.6191 35.41 5 216.5896 (d5) 34.93 6 -83.2881 1.9221 1.81600 46.62 0.5567 31.35 7 146.7938 3.7348 1.92286 20.88 0.6389 30.91 8 450.3947 (d8) 30.84 9* 62.0595 11.7752 1.75500 52.32 0.5474 32.50 10* -298.3563 0.1500 32.40 11 89.1584 7.1243 1.75500 52.32 0.5473 31.58 12 4204.1365 0.1500 31.25 13 292.1387 1.8854 1.84666 23.78 0.6191 30.57 14 49.3464 4.2505 28.17 15 89.7724 7.7654 1.59282 68.62 0.5440 28.16 16 -238.7255 (d16) 28.05 17(Aperture) ∞ 1.5029 18.30 18 352.4956 1.1783 1.79450 45.39 0.5571 18.98 19 84.5774 6.0991 18.64 20 -45.2263 1.1451 1.56732 42.82 0.5730 18.64 21 112.8095 3.1933 1.92286 20.88 0.6389 19.56 22 -1050.7962 (d22) 19.66 23 626.8806 9.1905 1.56908 71.34 0.5451 19.91 24 -37.0353 1.2895 1.77047 29.74 0.5950 20.12 25 -74.5939 0.1500 20.68 26 474.8486 5.3007 1.55032 75.50 0.5398 20.73 27 -76.2604 0.1500 20.72 28* 38.4236 9.0817 1.75500 52.32 0.5474 19.54 29* -256.1669 (d29) 18.50 30 463.5323 1.0000 1.77047 29.74 0.5950 17.75 31 32.7036 2.7040 16.53 32 57.6392 4.8029 1.92286 20.88 0.6389 16.56 33 -659.2621 1.0924 1.85135 40.10 0.5694 16.31 34 36.7781 2.4647 15.76 35 78.4743 1.9367 2.05080 26.94 0.6050 15.89 36 99.8014 (BF) 15.90 image plane [Aspheric data] Side 1 Side 2 Side 9 Side 10 K 0.00000 2.35533 0.00000 0.00000 A4 -1.24105E-07 -7.56786E-07 -6.73595E-07 5.06062E-07 A6 4.25409E-10 2.93475E-10 -4.15503E-11 -5.49670E-11 A8 3.73660E-14 2.27719E-14 2.46304E-14 A10 -3.67695E-17 -3.41835E-18 3.34503E-18 A12 2.03143E-20 Page 28 Page 29 K 0.00000 0.00000 A4 -4.26312E-07 2.04402E-06 A6 -1.01966E-10 -8.85613E-10 A8 -2.02912E-13 2.15596E-13 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 50.48 70.86 99.45 F-number 1.86 1.86 1.86 Full angle of view 2ω 51.17 35.76 25.50 Image height Y 23.15 23.15 23.15 Lens total length 220.01 212.28 220.03 Aperture Light Height 18.30 18.64 19.34 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 18.4889 18.4889 18.4889 d8 39.7537 17.7021 2.0000 d16 1.5000 18.8309 45.9514 d22 10.4434 6.5677 1.5006 d29 1.5000 2.3670 3.7647 BF 39.5481 39.5481 39.5481 [Lens group data] Group starting plane focal length G1 1 -75.85 G2 9 57.34 GM1 18 -62.84 GM2 23 28.23 GL 30 -37.70 G1a 1 -590.44 G1b 6 -89.54

[0112] Numerical Example 4 Unit: mm [surface data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 311.6163 2.5000 1.69350 53.19 0.5482 40.00 2* 136.5146 5.9412 37.92 3 1151.7443 2.3657 2.00100 29.13 0.5993 37.92 4 124.3290 8.4899 1.84666 23.78 0.6191 36.41 5 -431.9806 (d5) 36.10 6 -85.0257 1.9861 1.72000 50.34 0.5501 32.44 7 113.5740 4.0614 2.00060 25.46 0.6135 31.59 8 261.7557 (d8) 31.45 9 78.8439 8.3773 1.77250 49.62 0.5503 32.60 10 1561.4454 0.1500 32.52 11* 99.0119 8.4263 1.77250 49.62 0.5503 32.19 12* -205.8591 0.1500 31.97 13 -463.7281 1.9167 1.75520 27.51 0.6102 31.50 14 56.9633 1.8437 29.40 15 72.2035 9.0948 1.59282 68.62 0.5440 29.39 16 -328.2463 (d16) 29.24 17 (Aperture) ∞ 1.7216 18.88 18 606.1074 1.1643 1.53996 59.46 0.5440 19.42 19 130.0895 4.8418 19.15 20 -55.4721 1.1462 1.61272 58.72 0.5448 19.15 21 87.6780 3.6058 1.84666 23.78 0.6191 19.67 22 -3636.8029 (d22) 19.72 23 440.2837 4.3505 1.56908 71.34 0.5451 19.86 24 -81.8175 0.1500 19.90 25 -264.3169 1.1785 1.84666 23.78 0.6191 19.70 26 50.2209 7.7342 1.55032 75.50 0.5398 19.58 27 -97.5819 0.1500 19.68 28* 38.9624 7.0141 1.79952 42.23 0.5672 19.55 29* -926.7469 (d29) 19.45 30 48.6965 1.0285 1.85135 40.10 0.5694 17.75 31 26.9912 4.4401 16.74 32 102.1974 3.1431 2.00060 25.46 0.6135 16.74 33 -295.9863 1.0021 1.58144 40.75 0.5774 16.72 34 32.2532 1.1293 16.58 35 31.2720 2.6518 2.00060 25.46 0.6135 17.21 36 37.8102 (BF) 16.95 image plane [Aspheric data] Side 1 Side 2 Side 11 Side 12 K 0.00000 5.39173 0.00000 0.00000 A4 1.42480E-08 -3.85020E-07 -2.68590E-07 5.12537E-07 A6 4.94688E-10 4.03420E-10 -1.23602E-10 -1.35198E-10 A8 -5.88570E-14 1.44025E-13 8.87559E-14 A10 7.93126E-18 -6.01158E-17 -3.57873E-17 A12 2.62959E-21 Page 28 Page 29 K 0.00000 0.00000 A4 -1.15509E-06 5.32956E-07 A6 -1.17352E-10 -5.38300E-11 A8 -1.07536E-12 -4.38520E-13 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 50.49 70.87 99.47 F-number 1.86 1.86 1.86 Full angle of view 2ω 51.19 35.48 25.40 Image height Y 23.15 23.15 23.15 Lens total length 220.05 220.05 220.05 Aperture Light Height 18.88 18.77 19.77 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 15.5738 15.5738 15.5738 d8 42.2376 27.1553 2.0000 d16 1.5000 27.6823 51.0936 d22 13.2514 4.3553 1.5002 d29 3.7043 1.5004 6.0996 BF 42.0228 42.0228 42.0228 [Lens group data] Group starting plane focal length G1 1 -86.39 G2 9 64.19 GM1 18 -87.04 GM2 23 38.47 GL 30 -68.62 G1a 1 -834.76 G1b 6 -101.22

[0113] Numerical Example 5 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 281.3645 2.5000 1.69350 53.19 0.5482 40.00 2* 125.3057 11.2808 37.67 3 -201.6454 2.3508 2.00330 28.27 0.5979 37.70 4 508.2738 7.1859 2.00060 25.46 0.6138 37.11 5 -158.3180 (d5) 37.00 6 -81.9135 2.0474 1.65844 50.88 0.5559 33.04 7 95.5985 4.5696 2.00060 25.46 0.6138 32.16 8 208.4473 (d8) 32.00 9 81.2758 6.7243 1.77250 49.62 0.5503 33.18 10 269.8461 0.1500 33.12 11* 107.8656 10.7385 1.77250 49.62 0.5503 33.21 12* -173.5250 0.1500 32.85 13 -330.0706 2.0065 1.71736 29.52 0.6047 32.50 14 57.8929 1.6966 30.83 15 70.1134 11.5004 1.59282 68.62 0.5440 30.82 16 -185.7188 (d16) 30.74 17(Aperture) ∞ 1.9124 20.35 18 1882.7325 1.2458 1.58913 61.25 0.5402 20.66 19 269.5565 4.0242 20.46 20 -65.5747 1.2328 1.53996 59.46 0.5440 20.47 21 69.2662 3.8503 1.84666 23.78 0.6191 20.76 22 328.0764 (d22) 20.73 23 187.0072 3.6869 1.56908 71.34 0.5451 20.76 24 -184.0808 0.1500 20.72 25 -13535.0048 1.2386 1.78470 26.29 0.6135 20.57 26 42.6708 7.1410 1.55032 75.50 0.5398 20.17 27 -645.2253 0.1500 20.18 28* 46.5867 7.1309 1.77250 49.62 0.5503 20.18 29* -185.8884 (d29) 19.90 30 57.7837 1.0000 1.95375 32.32 0.5900 17.00 31 29.2279 3.5484 16.26 32 91.4720 5.7686 1.77047 29.74 0.5950 16.28 33 48.8625 0.8623 16.56 34 40.1832 6.5440 2.00060 25.46 0.6138 17.49 35 -258.7346 1.0545 1.63980 34.57 0.5916 17.38 36 41.8225 (BF) 16.97 image plane [Aspheric data] Side 1 Side 2 Side 11 Side 12 K 0.00000 6.14793 0.00000 0.00000 A4 4.84623E-07 -4.36557E-09 -2.16569E-07 5.38315E-07 A6 3.33692E-10 2.51469E-10 -7.79992E-11 -1.36615E-10 A8 -1.34246E-14 1.53133E-13 1.34581E-13 A10 -5.12482E-18 -4.99881E-17 -4.87903E-17 A12 8.50886E-21 Page 28 Page 29 K 0.00000 0.00000 A4 -6.22513E-07 1.06649E-06 A6 3.38964E-10 -1.53868E-10 A8 -9.92755E-13 -6.15448E-13 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 50.49 70.87 99.47 F-number 1.86 1.86 1.86 Full angle of view 2ω 51.18 35.60 25.40 Image height Y 23.15 23.15 23.15 Lens total length 235.03 235.03 235.03 Aperture light height 20.35 19.76 20.99 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 13.7278 13.7278 13.7278 d8 47.0456 28.1133 2.0000 d16 1.5000 30.3290 55.5123 d22 13.8865 6.1652 1.5000 d29 3.6754 1.5000 7.0952 BF 41.7562 41.7563 41.7563 [Lens group data] Group starting plane focal length G1 1 -86.27 G2 9 68.34 GM1 18 -120.18 GM2 23 46.32 GL 30 -85.42 G1a 1 -703.31 G1b 6 -107.30

[0114] Numerical Example 6 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 3518.3257 2.5000 1.69350 53.19 0.5482 40.00 2* 230.5707 5.2425 37.92 3 2284.2824 2.3667 2.00060 25.46 0.6135 37.94 4 131.9168 8.6307 1.80809 22.76 0.6285 36.48 5 -339.6346 (d5) 36.18 6 -81.0323 1.9971 1.65100 56.24 0.5419 32.68 7 100.1240 3.9502 2.05080 26.94 0.6050 31.70 8 187.3922 (d8) 31.52 9 78.8779 8.2062 1.75500 52.32 0.5473 32.55 10 912.3286 0.1500 32.48 11* 96.9923 9.1170 1.75500 52.32 0.5474 32.25 12* -172.7558 0.1500 32.02 13 -336.5709 1.9284 1.77047 29.74 0.5950 31.54 14 57.1395 1.5158 29.61 15 68.9572 10.0930 1.59282 68.62 0.5440 29.60 16 -242.4118 (d16) 29.48 17(Aperture) ∞ 1.9734 18.96 18 4634.3778 1.1665 1.51680 64.20 0.5342 19.45 19 130.0668 4.9976 19.16 20 -53.0958 1.1474 1.51742 52.15 0.5588 19.16 21 89.7039 3.0869 1.86966 20.02 0.6433 19.64 22 566.7700 (d22) 19.66 23 232.6384 4.7665 1.59282 68.62 0.5440 19.78 24 -82.4607 0.1500 19.79 25 -229.2333 1.1689 1.85451 25.15 0.6102 19.54 26 46.0455 7.4725 1.56908 71.34 0.5451 19.33 27 -128.9706 0.1500 19.40 28* 40.7509 6.7351 1.80610 40.93 0.5713 19.30 29* -568.8684 (d29) 18.90 30 47.4796 1.0000 1.83400 37.17 0.5785 17.58 31 26.6553 4.4226 16.64 32 100.5787 3.1710 2.00060 25.46 0.6135 16.64 33 -286.9185 1.0000 1.60342 38.01 0.5826 16.64 34 34.9467 0.8429 16.59 35 31.4712 2.6493 2.00060 25.46 0.6135 17.25 36 37.9154 (BF) 16.98 image plane [Aspheric data] Side 1 Side 2 Side 11 Side 12 K 0.00000 25.42020 0.00000 0.00000 A4 9.19987E-07 5.20506E-07 -2.84753E-07 5.77171E-07 A6 1.92718E-10 1.54551E-10 -1.14632E-10 -1.70083E-10 A8 2.38884E-15 1.42675E-13 1.16528E-13 A10 -1.29807E-17 -4.73228E-17 -3.73734E-17 A12 1.20788E-20 Page 28 Page 29 K 0.00000 0.00000 A4 -1.02000E-06 6.45843E-07 A6 4.80532E-10 3.14944E-10 A8 -1.43450E-12 -9.55054E-13 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 50.49 70.87 99.47 F-number 1.86 1.86 1.86 Full angle of view 2ω 51.19 35.49 25.40 Image height Y 23.15 23.15 23.15 Lens total length 220.01 220.01 220.01 Aperture Light Height 18.96 18.73 19.80 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d5 15.5373 15.5373 15.5373 d8 42.1109 26.7452 2.0000 d16 1.5000 27.8172 50.8950 d22 13.1948 4.6765 1.5000 d29 3.9332 1.5000 6.3439 BF 41.9860 41.9860 41.9860 [Lens group data] Group starting plane focal length G1 1 -85.72 G2 9 63.97 GM1 18 -88.07 GM2 23 39.96 GL 30 -74.36 G1a 1 -721.22 G1b 6 -103.02

[0115] Numerical Example 7 Unit: mm [Face data] Surface number rd nd vd Pg_F SD Object surface ∞ (d0) 1* 5369.9957 2.5000 1.69350 53.19 0.5482 40.00 2* 147.6610 9.0477 37.42 3 -371.4265 3.0452 1.90043 37.37 0.5765 37.30 4 -185.5960 (d4) 37.17 5 -76.5820 2.0532 1.72916 54.10 0.5447 32.75 6 139.4119 4.9453 1.92119 23.96 0.6201 32.47 7 1060.9288 (d7) 32.40 8 83.8566 7.0926 1.77250 49.46 0.5538 33.79 9 275.9113 0.9938 33.47 10* 92.2613 11.5367 1.72916 54.67 0.5453 33.67 11* -143.5622 0.1500 33.38 12 -240.7984 2.0815 1.73037 32.23 0.5898 32.98 13 60.7926 2.1549 31.19 14 79.0398 11.2800 1.56908 71.34 0.5451 31.18 15 -161.1571 (d15) 31.12 16 (Aperture) ∞ 2.0806 20.83 17 -3057.9388 1.2763 1.51680 64.20 0.5342 21.13 18 167.2024 5.0853 20.87 19 -59.7952 1.2591 1.57501 41.51 0.5766 20.86 20 103.2202 4.3316 1.86966 20.02 0.6433 21.46 21 -333.3329 (d21) 21.51 22 -1190.7571 3.1144 1.59282 68.62 0.5440 21.52 23 -115.0101 0.1500 21.54 24 -1560.5921 1.2905 1.85451 25.15 0.6102 21.35 25 45.2752 8.4733 1.56908 71.34 0.5451 21.05 26 -159.2413 0.1500 21.13 27* 44.2893 7.5433 1.77250 49.46 0.5538 21.14 28* -315.3355 (d28) 20.85 29 47.3850 1.0000 1.91650 31.60 0.5911 17.28 30 28.6917 3.6468 16.49 31 75.7770 1.9876 1.78880 28.43 0.6008 16.52 32 42.4180 2.9867 16.38 33 39.1846 5.5307 2.00060 25.46 0.6135 17.68 34 271.2764 1.0810 1.61310 44.36 0.5604 17.49 35 35.4308 (BF) 16.95 image plane [Aspheric data] Side 1 Side 2 Side 10 Side 11 K 0.00000 9.47553 0.00000 0.00000 A4 1.12521E-06 6.13957E-07 -2.41393E-07 6.73107E-07 A6 -1.13388E-10 -1.51193E-10 -1.12746E-11 -1.30608E-10 A8 3.39252E-14 5.40156E-14 5.70617E-14 A10 -2.84058E-19 -1.32704E-17 -1.49757E-17 A12 6.05844E-21 27th page 28th page K 0.00000 0.00000 A4 -8.95409E-07 2.71693E-07 A6 7.07807E-11 1.75445E-12 A8 -9.32656E-13 -4.91948E-13 [Various data] Zoom ratio 1.97 Wide Angle Mid-Telephoto Focal length 50.50 70.88 99.49 F-number 1.86 1.86 1.86 Full angle of view 2ω 51.01 35.53 25.50 Image height Y 23.15 23.15 23.15 Lens total length 235.00 235.00 235.00 Aperture light height 20.83 20.06 21.44 [Variable interval data] Wide Angle Mid-Telephoto d0∞∞∞∞ d4 15.2284 15.2284 15.2284 d7 49.9123 31.2121 2.0000 d15 1.5000 32.0820 57.6354 d21 13.9136 4.4918 1.5000 d28 3.9600 1.5000 8.1505 BF 42.6199 42.6199 42.6199 [Lens group data] Group starting plane focal length G1 1 -85.05 G2 8 69.73 GM1 17 -135.79 GM2 22 46.94 GL 29 -77.74 G1a 1 -503.96 G1b 5 -110.81

[0116] [Conditional expression corresponding value] EX1 EX2 EX3 EX4 EX5 EX6 EX7 (1) Δ1ab / SD1 0.274 0.233 0.238 0.266 0.279 0.265 0.291 (2) d12W / LTW 0.193 0.192 0.181 0.192 0.200 0.191 0.212 (3) d2MT / LTT 0.179 0.189 0.216 0.240 0.244 0.240 0.254 (4)LTW*SD1 / Ymax^2 18.653 16.420 16.421 16.424 17.542 16.421 17.540 (5) f1b / f1a 0.183 0.265 0.152 0.121 0.153 0.143 0.220 (6) FnohT / Ymax 0.844 0.789 0.835 0.854 0.907 0.855 0.926 (7) f1b / f1 1.298 1.321 1.180 1.172 1.244 1.202 1.303 (8) f1 / fw -1.344 -1.658 -1.502 -1.711 -1.709 -1.698 -1.684 (9) f2 / fT 0.557 0.627 0.577 0.645 0.687 0.643 0.701 (10) fMLT / fT 2.442 1.748 1.930 1.700 1.819 1.756 1.740 (11) fL / fT -0.967 -0.467 -0.379 -0.690 -0.859 -0.748 -0.781 (12) vd2p 75.50 68.62 68.62 68.62 68.62 68.62 71.34 (13) ΔPgf2p 0.0274 0.0192 0.0192 0.0192 0.0192 0.0192 0.0252 (14) vdMp 75.50 75.50 75.50 75.50 75.50 71.34 71.34 (15) ΔPgfMp 0.0274 0.0274 0.0274 0.0274 0.0274 0.0252 0.0252 (16) βLW 1.41 2.09 2.21 1.68 1.57 1.62 1.62

[0117] In order to simplify the focusing mechanism and reduce the product diameter, it is desirable for the first lens group G1 to have a small amount of movement during zooming, and it is even more desirable for it to be fixed relative to the image plane during zooming.

[0118] An anti-vibration mechanism may be provided by shifting part or all of the middle lens group GM and the final lens group GL in a direction substantially perpendicular to the optical axis.

[0119] The intermediate lens group GM and the final lens group GL may be partially or entirely moved in the optical axis direction for focusing, or may be used only for fine driving to detect the defocus direction.

[0120] The movement of the intermediate lens group GM during zooming is not limited to GM1 and GM2, and it may be divided into a plurality of groups and moved separately. In that case, it can be used to improve coma and astigmatism especially in the intermediate zoom range.

[0121] A filter with approximately flat surfaces on both sides may be placed before or after each lens group or within the group. In particular, a cover glass for the image sensor, an infrared cut filter, a low-pass filter, a neutral density filter, etc. may be placed between the final lens group and the image plane.

[0122] Although not described in the examples, a hybrid aspheric surface, a diffraction grating, a refractive index gradient lens, etc. may be used as a lens element to achieve miniaturization and high performance. The shape of the aspheric surface may have an inflection point and be a gull-wing shape, or may be a free curved surface.

[0123] Although the examples show known glasses, the numerical values ​​showing the properties of the materials, including the refractive index, Abbe number, anomalous dispersion ΔPgF, and partial dispersion ratio PgF, may take any numerical value for the purpose of miniaturization, weight reduction, and good aberration correction, and the materials and numerical values ​​are not limited except for those specified by the conditional expressions in the claims. For example, a material with a refractive index nd of 1.45 or less or 2.00 or more may be used, and a material with an Abbe number νd of 17.0 or less or 95.0 or more may be used. [Explanation of symbols]

[0124] G1 First lens group G2 2nd lens group GM intermediate lens group GL final lens group G1a 1a lens group G1b 1bth lens group GM1 M1 lens group GM2 M2 lens group I image plane S aperture stop

Claims

1. The optical system includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, an intermediate lens group GM having a plurality of lens groups, and a final lens group GL having a negative refractive power. During zooming from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 decreases, the distance between the second lens group G2 and the intermediate lens group GM changes, and the distance between the intermediate lens group GM and the final lens group GL changes. The intermediate lens group GM includes, in order from the object side, an M1 lens group GM1 having a negative refractive power and an M2 lens group GM2 having a positive refractive power, When zooming from the wide-angle end to the telephoto end, the distance between the M1 lens group GM1 and the M2 lens group GM2 changes. an aperture stop is provided adjacent to the intermediate lens group GM or within the intermediate lens group GM; The first lens group G1 includes, in order from the object side, a first-a lens group G1a having a negative refractive power and a first-b lens group G1b having a negative refractive power. During focusing from infinity to a close distance, the first lens group G1b moves toward the object side, A large aperture ratio zoom lens characterized by satisfying the following conditional expressions: (1) 0.10 < Δ1ab / SD1 < 0.90 Δ1ab: the distance parallel to the optical axis between the position of the maximum effective ray height on the surface closest to the image side of the 1a lens group G1a and the position of the maximum effective ray height on the surface closest to the object side of the 1b lens group G1b when focusing on infinity SD1: maximum effective ray height of the first lens group G1

2. 2. The large aperture ratio zoom lens according to claim 1, wherein, during focusing from infinity to a close distance, all of the lenses in the first lens subgroup G1b and the like are fixed relative to the image plane.

3. 2. The large aperture ratio zoom lens according to claim 1, wherein the final lens group GL is fixed with respect to an image plane during zooming from the wide-angle end to the telephoto end.

4. 2. The large aperture ratio zoom lens according to claim 1, wherein the first a lens group G1a has at least one lens L1ap having a positive refractive power, and the first b lens group G1b has a lens L1bm having a negative refractive power with a concave surface facing the object side.

5. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (2) 0.10 < d12W / LTW < 0.30 d12W: the distance on the optical axis between the surface of the first lens group G1 closest to the image side and the surface of the second lens group G2 closest to the object side at the wide-angle end and when focusing on infinity LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end

6. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (3) 0.05 < d2MT / LTT < 0.35 d2MT: the distance on the optical axis between the surface of the second lens group G2 closest to the image side and the surface of the intermediate lens group GM closest to the object side at the telephoto end and when focusing on infinity LTT: The distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the telephoto end

7. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (4) 4.50 < (LTW*SD1) / (Ymax^2) < 60.0 LTW: Distance on the optical axis from the surface closest to the object to the image plane when focusing at infinity at the wide-angle end SD1: maximum effective ray height of the first lens group G1 Ymax: Maximum image height

8. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (5) 0.01 < f1b / f1a < 4.50 f1b: the focal length of the 1b lens group G1b f1a: the focal length of the 1a lens group G1a

9. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (6) 0.25 < FnohT / Ymax < 1.40 FnohT: Height of aperture diaphragm when focused at infinity at telephoto end Ymax: Maximum image height

10. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (7) 0.05 < f1b / f1 < 5.70 (8) -10.0 < f1 / fW < -0.50 (9) 0.20 < f2 / fT < 1.30 (10) 0.10 < fMLT / fT < 9.50 (11) -50.0 < fL / fT < -0.01 f1b: the focal length of the 1b lens group G1b f1: focal length of the first lens group G1 when focused at infinity fW: focal length of the entire lens system at the wide-angle end and focused at infinity f2: focal length of the second lens group G2 fT: focal length of the entire lens system at the telephoto end, focused at infinity fMLT: composite focal length from the intermediate lens group GM to the final lens group GL at the telephoto end fL: focal length of the final lens group GL

11. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (12) 55.0 < vd2p (13) 0.005 < ΔPgF2p (14) 60.0 < vdM2p (15) 0.015 < ΔPgFM2p vd2p: the Abbe number of the positive lens Lvd2p having the largest Abbe number in the second lens group G2 ΔPgF2P: ΔPgF of the positive lens Lvd2p in the second lens group G2 Where: ΔPgF: Anomalous dispersion between the g and F lines, and is expressed by the following formula. ΔPgF=PgF-0.64833+0.00180νd PgF = (ng-nF) / (nF-nC): partial dispersion ratio between g and F lines ng: refractive index for g-line (wavelength λ=435.84 nm) nF: Refractive index for F line (wavelength λ = 486.13 nm) nC: Refractive index for C line (wavelength λ=656.27 nm) vdMp: the Abbe number of the positive lens LvdMp having the largest Abbe number in the intermediate lens group GM ΔPgFMP: ΔPgF of the positive lens LvdMp in the intermediate lens group GM

12. 2. The large aperture ratio zoom lens according to claim 1, wherein the following condition is satisfied: (16) 1.10 < βLW < 3.00 βLW: lateral magnification of the final lens group GL at the wide-angle end when focusing on infinity

Images