JP7630814B2 - Large aperture zoom lens - Google Patents

Description

The present invention relates to a large-aperture zoom lens. In particular, it relates to a large-aperture zoom lens that includes a standard range in its magnification range, has a small maximum F-number, is compact in overall length, and is capable of high-speed autofocus control.

Conventionally, large-aperture zoom lenses with small maximum apertures are required to provide high imaging performance by effectively correcting various aberrations across the entire zoom range, to miniaturize the entire optical system, and to reduce the weight of the focus lens group in order to enable high-speed autofocus control.

For example, Patent Document 1 discloses a zoom lens having a relatively long back focus, the zoom lens being composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, arranged in that order from the object side to the image side.

Patent Document 2 also discloses a zoom lens with a relatively long back focus, which is composed of a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with negative refractive power, and a fifth lens group with positive refractive power, or a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, which are arranged in that order from the object side to the image side.

JP 2011-128361 A JP 2012-123156 A

However, the zoom lenses disclosed in the above patent documents have the following problems:

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

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

In the conventional zoom lens disclosed in Patent Document 2, the focus lens group is insufficiently lightweight, just like the zoom lens disclosed in Patent Document 1.

In addition, although it can be used with single-lens reflex cameras equipped with full-size image sensors, the relatively long back focus and overall length make it unsuitable for use with mirrorless cameras.

The present invention was made in consideration of the above-mentioned problems with the conventional examples, and aims to obtain a large-aperture zoom lens that includes a standard range in its magnification range, has a small maximum F-number, is compact in overall length, and is capable of high-speed autofocus control.

In order to achieve the above object, a large-aperture zoom lens embodying the present invention comprises, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a rear lens group GR having negative refractive power including one or more lens groups, and the fifth lens group G5 has a negative meniscus having a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to an object at a close distance. The focusing lens LF is made up of a focusing lens having a first lens group G1 and a second lens group G2, and when the magnification is changed from the wide-angle end to the telephoto end, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the rear lens group GR increases, and the following conditional formula is satisfied:
(1) -3.0<f5/f4<-1.0
Where:
f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5

Furthermore, a large aperture zoom lens embodying the present invention is preferably characterized in that, when changing magnification from the wide-angle end to the telephoto end, the lens closest to the image surface in the rear lens group GR is fixed with respect to the image surface.

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

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

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

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

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

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

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

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

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

1 is a lens configuration diagram of a large-aperture zoom lens according to a first embodiment of the present invention. 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at the wide-angle end when focused on infinity. 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at an intermediate focal length and focused on infinity. 4A to 4C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 1 at the telephoto end when focused on infinity. 4A to 4C are lateral aberration diagrams of the large-aperture zoom lens of Example 1 at the wide-angle end when focused on infinity. 4A to 4C are lateral aberration diagrams of the large-aperture zoom lens of Example 1 at an intermediate focal length and focused on infinity. 4A to 4C are lateral aberration diagrams of the large-aperture zoom lens of Example 1 at the telephoto end when focused on infinity. FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a second embodiment of the present invention. 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 at the wide-angle end and focused on infinity. 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 when the lens is at an intermediate focal length and focused on an object at infinity. 11A to 11C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 2 at the telephoto end when focused on infinity. 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 at the wide-angle end and focused on infinity. 6A to 6C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 when the lens is at an intermediate focal length and focused on an object at infinity. 11A to 11C are lateral aberration diagrams of the large-aperture zoom lens of Example 2 at the telephoto end when focused on infinity. FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to a third embodiment of the present invention. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 at the wide-angle end when focused on infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 when the lens is at an intermediate focal length and focused on an object at infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 3 at the telephoto end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 at the wide-angle end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 at an intermediate focal length and focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 3 at the telephoto end when focused on infinity. FIG. 11 is a lens configuration diagram of a large-aperture zoom lens according to Example 4 of the present invention. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 at the wide-angle end and when focused on infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 when the lens is at an intermediate focal length and focused on an object at infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 4 at the telephoto end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at the wide-angle end and when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at an intermediate focal length and focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 4 at the telephoto end when focused on infinity. FIG. 13 is a lens configuration diagram of a large-aperture zoom lens according to a fifth embodiment of the present invention. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 at the wide-angle end and focused on infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 when the lens is at an intermediate focal length and focused on an object at infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 5 at the telephoto end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 at the wide-angle end and focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 when the lens is at an intermediate focal length and focused on an object at infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 5 at the telephoto end when focused on infinity. FIG. 13 is a lens configuration diagram of a large-aperture zoom lens according to a sixth embodiment of the present invention. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 at the wide-angle end when focused on infinity. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 when the lens is focused at infinity at an intermediate focal length. 13A to 13C are longitudinal aberration diagrams of the large-aperture zoom lens of Example 6 at the telephoto end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 at the wide-angle end when focused on infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 when the lens is at an intermediate focal length and focused on an object at infinity. 13A to 13C are lateral aberration diagrams of the large-aperture zoom lens of Example 6 at the telephoto end when focused on infinity.

Below, an embodiment of a large aperture zoom lens according to the present invention will be described in detail with reference to the drawings. In the present invention, a lens unit refers to a single lens or a cemented lens that as a whole constitutes one optical element.

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

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

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

The fifth lens group G5 also comprises a focusing lens LF, which is a negative meniscus lens with a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to a close object.

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

Therefore, at the wide-angle end, the first lens group G1 with positive refractive power and the second lens group G2 with negative refractive power are arranged close together so that their combined refractive power is negative, and the third lens group G3 with an overall positive refractive power is arranged at a position away from the combined system of the first lens group G1 and the second lens group G2 toward the image side, the fourth lens group G4 with positive refractive power is arranged at a position further toward the image side, the fifth lens group G5 with negative refractive power is arranged behind the fourth lens group, and the rear lens group GR is arranged behind it.

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

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

In order to enable high-speed autofocus control by moving a lightweight lens, it is preferable to miniaturize the focusing lens LF. In order to miniaturize the focusing lens LF, it is important to make its effective diameter as small as possible. However, if one attempts to place the focusing lens LF in the final lens group closest to the image plane in order to reduce its effective diameter, it becomes difficult to place the electrical circuit board for communication with the camera body, which is placed around the mount, and further, prioritizing the placement of the electrical circuit board undesirably excessively restricts the effective diameter of the focusing lens LF.

In this embodiment, the fifth lens group G5 is arranged adjacent to the fourth lens group G4, and the distance between the fifth lens group G5 and the rear lens group GR is increased when changing magnification from the wide-angle end to the telephoto end. This makes it possible to secure a sufficient movement space on the image surface side of the focusing lens LF, which moves more at the telephoto end when focusing from an infinite object to a close object. Furthermore, in this embodiment, by arranging the fifth lens group G5 adjacent to the image surface side of the fourth lens group G4, it is possible to more easily secure the movement space on the image surface side of the focusing lens LF. Also, in this embodiment, the focusing lens LF is a negative meniscus lens with a convex surface facing the object side, and aberration fluctuations during focusing can be suppressed.

Conditional formula (1) defines the ratio between the focal length of the fourth lens group G4 and the focal length of the fifth lens group G5.

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

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

By limiting the lower limit of the above-mentioned conditional formula (1) to -2.2 and the upper limit to -1.6, the aforementioned effect can be more reliably achieved.

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

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

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

If the lower limit of conditional expression (2) is exceeded and the refractive power of the third lens group G3 becomes large, when the lens spacing between the third lens group G3 and the fourth lens group G4 is changed during zooming to suppress field curvature, the spherical aberration occurring in the third lens group G3 causes an increase in the spherical aberration fluctuation in the intermediate zoom range.

When the upper limit of conditional expression (2) is exceeded and the refractive power of the third lens group G3 becomes small, the outer diameter of the fourth lens group G4 becomes large, and the refractive power of the fourth lens group G4 becomes too large, so that the sensitivity to spherical aberration in the fourth lens group G4 increases. Furthermore, the sensitivity to decentering increases, making it difficult to suppress manufacturing variations, which may have a negative effect on productivity.

By limiting the lower limit of the above-mentioned conditional expression (2) to 2.1 and the upper limit to 3.4, the aforementioned effect can be more reliably achieved.

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

When the lower limit of conditional expression (3) is exceeded and the refractive power of the first lens group G1 becomes large, it becomes difficult to correct spherical aberration and lateral chromatic aberration at the telephoto end, and sufficient optical performance cannot be obtained. Furthermore, when the refractive power of the second lens group G2 becomes small, the overall lens length at the wide-angle end becomes large.

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

By limiting the lower limit of the above-mentioned conditional expression (3) to -6.4 and the upper limit to -4.6, the above-mentioned effect can be more reliably achieved.

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

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

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

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

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

By limiting the lower limit of the above-mentioned conditional expression (4) to 15.0 and the upper limit to 22.0, the above-mentioned effect can be more reliably achieved.

By limiting the lower limit of the above-mentioned conditional formula (5) to 70.0 and the upper limit to 96.0, the above-mentioned effect can be more reliably achieved.

By limiting the lower limit of the above-mentioned conditional expression (6) to 3.8 and the upper limit to 4.7, the above-mentioned effect can be more reliably achieved.

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

When the lower limit of conditional expression (7) is exceeded and the refractive power of lens group G41 becomes large, the sensitivity to relative shift between lens group G41 and positive lens G42 increases, and the deterioration of optical performance due to manufacturing errors increases, which may adversely affect productivity.

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

By limiting the lower limit of the above-mentioned conditional expression (7) to 0.39 and the upper limit to 0.46, the above-mentioned effect can be more reliably achieved.

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

When the imaging magnification is increased, the rear lens group GR, which has negative refractive power, can shorten the focal length of each lens group that is positioned closer to the object than the rear lens group GR, which is advantageous for reducing the overall lens length.

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

By limiting the lower limit of the above-mentioned conditional expression (8) to -0.004, the above-mentioned effect can be more reliably achieved.

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

By arranging the lens unit RF1, which has at least one positive lens with a convex surface facing the object side and has a positive refractive power overall, closest to the object side in the rear lens group GR, the light diameter of the rear lens group GR can be reduced, and the outer diameter around the mount of the camera body can be prevented from becoming large. Furthermore, by arranging the lens unit RR1, which has at least one negative lens closest to the image side and has a negative refractive power overall, the exit angle of off-axis light rays can be appropriately controlled, making it easier to improve the curvature of field.

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

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

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

In the large aperture zoom lens of this embodiment, the rear lens group GR is composed of two lens groups, and the distance between the two lens groups increases when changing magnification from the wide-angle end to the telephoto end. This allows the spherical aberration and astigmatism to be changed to the under side in the intermediate region and the telephoto end region of the magnification range, and makes it possible to appropriately correct the change in the curvature of field when changing magnification.

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

By arranging the lens group RF2, which has at least one positive lens with a convex surface facing the object side and has a positive refractive power overall, closest to the object side in the rear lens group GR, it is possible to reduce the light diameter of the rear lens group GR, and therefore to prevent the outer diameter from becoming large around the mount of the camera body. Furthermore, by arranging the lens group RR2, which has at least one negative lens closest to the image side and has a negative refractive power overall, it is possible to appropriately control the exit angle of off-axis light rays, making it easy to improve the curvature of field throughout the entire magnification range.

When the lower limit of conditional expression (10) is exceeded and the positive refractive power of lens group RF2 becomes small, the ray height of lens group RR2, which is the lens group closest to the image plane in the image-side lens group GR, becomes too large, making it difficult to arrange lenses around the mount of the camera body. In addition, the negative refractive power of lens group RR2 becomes too large, so the negative refractive power of the rear lens group GR becomes large, which is advantageous for reducing the overall lens length, but makes it difficult to correct aberrations.

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

By limiting the lower limit of the above-mentioned conditional formula (10) to -1.4 and the upper limit to -1.1, the above-mentioned effect can be more reliably achieved.

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

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

By limiting the lower limit of the above-mentioned conditional expression (11) to 0.85 and the upper limit to 0.95, the above-mentioned effect can be more reliably achieved.

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

Figure 1 is a lens configuration diagram of a large aperture zoom lens according to a first embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image plane, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image plane. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 decreases, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

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

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

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

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

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

The fifth lens group G5 is composed of a negative meniscus lens L13 with its convex surface facing the object side as the focusing lens LF.

The sixth lens group G6 is composed of a cemented lens consisting of a biconvex lens L14 and a biconcave lens L15 having positive refractive power as the lens unit RF1, and a biconcave lens L16 having negative refractive power as the lens unit RR1.

Figure 8 is a lens configuration diagram of a large aperture zoom lens according to a second embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

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

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

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

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

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

The fifth lens group G5 is composed of a negative meniscus lens L16 with its convex surface facing the object side as the focusing lens LF.

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

Figure 15 is a lens configuration diagram of a large aperture zoom lens according to a third embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

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

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

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

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

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

The fifth lens group G5 is composed of a negative meniscus lens L13 with its convex surface facing the object side as the focusing lens LF.

The sixth lens group G6 is composed of a cemented lens consisting of a biconvex lens L14 and a biconcave lens L15 having positive refractive power as the lens unit RF1, and a biconcave lens L16 having negative refractive power as the lens unit RR1.

Figure 22 is a lens configuration diagram of a large aperture zoom lens according to a fourth embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 is fixed relative to the image surface. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, and the distance between the fifth lens group G5 and the sixth lens group G6 increases.

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

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

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

The third lens group G3 is composed of a biconvex lens L8, a cemented lens consisting of a biconvex lens L9 and a negative meniscus lens L10 with its concave surface facing the object side.

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

The fifth lens group G5 is composed of a negative meniscus lens L13 with its convex surface facing the object side as the focusing lens LF.

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

Figure 29 is a lens configuration diagram of a large aperture zoom lens according to a fifth embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 is fixed relative to the image surface. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, the distance between the fifth lens group G5 and the sixth lens group G6 increases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases.

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

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

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

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

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

The fifth lens group G5 is composed of a negative meniscus lens L13 with its convex surface facing the object side as the focusing lens LF.

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

Figure 36 is a lens configuration diagram of a large aperture zoom lens according to a sixth embodiment of the present invention.

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

When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 moves relative to the image surface, the third lens group G3 moves toward the object side, the fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, and the seventh lens group G7 is fixed relative to the image surface. In addition, the distance between the first lens group G1 and the second lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 decreases, the distance between the fourth lens group G4 and the fifth lens group G5 changes, the distance between the fifth lens group G5 and the sixth lens group G6 increases, and the distance between the sixth lens group G6 and the seventh lens group G7 increases.

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

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

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

The third lens group G3 is composed of a biconvex lens L8, a cemented lens consisting of a biconvex lens L9 and a concave meniscus lens L10 with its concave surface facing the object side.

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

The fifth lens group G5 is composed of a negative meniscus lens L13 with its convex surface facing the object side as the focusing lens LF.

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

The following describes numerical examples of the large aperture zoom lens of this embodiment.

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

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

The (Aperture) next to a surface number indicates that an aperture stop is located at that position. The radius of curvature for the plane or aperture stop is marked ∞ (infinity).

[Aspheric Data] shows the values of each coefficient that gives the aspheric shape of the lens surfaces 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, ..., A16 are the aspheric coefficients of degrees 4 to 16, respectively.

[Various data] shows values such as zoom ratio and focal length for each focal length state.

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

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

In addition, for all the values of the following specifications, the focal length f, radius of curvature r, distance between each surface d, and other length units are in millimeters (mm) unless otherwise specified, but this is not limited to this because the optical system provides equivalent optical performance with proportional magnification and proportional reduction.

A list of the conditional expressions corresponding to each of these numerical examples is also provided.

In addition, in the longitudinal and lateral aberration diagrams corresponding to the numerical examples, d, g, and C represent the d-line, g-line, and C-line, respectively, and △S and △M represent the sagittal and meridional image surfaces, respectively.

Numerical Example 1
Unit: mm
[Face data]
Surface number rd nd vd
1 500.0000 1.8000 1.98613 16.48
2 270.4400 4.9300 1.48749 70.44
3 -450.0700 0.1500
4 56.2500 8.7900 1.48749 70.44
5 209.3700 (d5)
6* 200.0000 1.8000 1.85135 40.10
7* 21.3000 8.0200
8 -43.1100 1.0000 1.59282 68.62
9 22.4200 7.8400 1.77047 29.74
10 -64.5900 3.0300
11 -24.0800 0.9000 1.49700 81.61
12 -90.1400 (d12)
13(Aperture) ∞ 1.2000
14 42.6900 4.7600 1.49700 81.61
15 -76.6400 0.1500
16 38.2000 9.2900 1.43700 95.10
17 -27.0500 0.9000 1.90043 37.37
18∞ (d18)
19 25.5400 9.0000 1.43700 95.10
20 -36.9400 0.3500
21* 1000.0000 2.9100 1.59201 67.02
22* -45.7500 (d22)
23* 293.2900 1.2000 1.69350 53.20
24* 30.9600 (d24)
25 46.0500 5.5800 1.87071 40.73
26 -326.8800 1.2000 1.51742 52.15
27 34.0000 5.3600
28 -201.6100 1.2000 1.56732 42.84
29 100.0000 (BF)
Image plane

[Aspheric data]
6th 7th 21st 22nd
K 0.00000 -1.00000 0.00000 0.00000
A4 9.64570E-06 2.25950E-05 -3.46960E-05 -3.56650E-06
A6 -2.46570E-08 -4.04980E-08 -6.29210E-08 -1.52480E-08
A8 8.35530E-11 8.62340E-10 1.83020E-09 1.48200E-09
A10 -1.48070E-13 -6.66800E-12 -4.65270E-12 -3.25320E-12
A12 1.22550E-16 2.99900E-14 0.00000E+00 0.00000E+00
A14 0.00000E+00 -5.06100E-17 0.00000E+00 0.00000E+00
23rd page 24th page
K 0.00000 0.00000
A4 3.03570E-05 3.12540E-05
A6 -2.12000E-07 -2.26890E-07
A8 6.14320E-10 7.70270E-10
A10 0.00000E+00 0.00000E+00
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.75
Wide Angle Mid Telephoto Focal Length 24.72 39.76 67.98
F-number 2.92 2.92 2.92
Full angle of view 2ω 85.24 56.96 34.33
Image height Y 21.63 21.63 21.63
Lens total length 135.00 145.60 171.09

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 12.6100 34.9600
d12 16.4800 7.4300 1.7100
d18 8.5600 4.5900 2.7000
d22 2.4000 2.0700 1.9000
d24 7.0800 19.9412 30.8878
BF 17.6206 17.6036 17.5749

[Lens group data]
Group Initial surface Focal length
G1 1 130.36
G2 6 -20.62
G3 14 64.03
G4 19 26.36
G5 23 -50.01
G6 25 -559.05
G41 19 36.14
G42 21 80.89
RF1 25 172.19
RR1 28 -117.66

Numerical Example 2
Unit: mm
[Face data]
Surface number rd nd vd
1 500.0000 1.8000 1.94595 17.98
2 253.4800 4.6800 1.48749 70.44
3 -438.1900 0.1500
4 53.5500 8.3100 1.48749 70.44
5 230.8900 (d5)
6* 328.4400 1.8000 1.85135 40.10
7* 22.1600 8.0500
8 -42.8100 1.0000 1.59282 68.62
9 23.7800 5.9900 1.77047 29.74
10 -74.4200 3.0500
11 -22.2800 0.9000 1.43700 95.10
12 -102.8000 (d12)
13(Aperture) ∞ 1.2000
14 72.6000 2.5600 1.72916 54.67
15 -600.9100 0.1500
16 39.5700 7.5300 1.43700 95.10
17 -29.2800 1.0000 1.88300 40.80
18 -178.4600 0.4400
19 110.2300 2.0800 1.43700 95.10
20∞ (d20)
21 55.2700 1.0000 1.80420 46.50
22 28.7800 5.2900 1.43700 95.10
23 1235.8300 0.1500
24 24.6800 9.2900 1.43700 95.10
25 -46.1500 0.3500
26* -1000.0000 2.6000 1.59201 67.02
27* -51.9400 (d27)
28* 151.5900 1.2000 1.69350 53.20
29* 26.9800 (d29)
30 41.1300 5.2100 1.91082 35.25
31 307.0700 0.1500
32 97.7100 1.2000 1.64769 33.84
33 29.3200 5.6800
34 -561.1500 1.2000 1.67300 38.26
35 100.0000 (BF)
Image plane ∞

[Aspheric data]
6th 7th 26th 27th
K 0.00000 -1.00000 0.00000 0.00000
A4 2.74630E-05 3.92360E-05 -3.98820E-05 -1.15420E-05
A6 -2.05280E-07 -1.46350E-07 -6.92930E-10 2.75680E-08
A8 1.21630E-09 2.95280E-10 1.42530E-09 1.17220E-09
A10 -4.41650E-12 6.50300E-12 -3.40870E-12 -2.36990E-12
A12 9.59160E-15 -5.18360E-14 0.00000E+00 0.00000E+00
A14 -1.13240E-17 1.84260E-16 0.00000E+00 0.00000E+00
A16 5.58660E-21 -2.87740E-19 0.00000E+00 0.00000E+00
Page 28 Page 29
K 0.00000 0.00000
A4 3.23770E-05 3.31730E-05
A6 -4.21570E-07 -4.60990E-07
A8 3.21000E-09 3.76160E-09
A10 -1.31270E-11 -1.61700E-11
A12 2.37100E-14 3.40450E-14
A14 0.00000E+00 -1.15100E-17
A16 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.75
Wide Angle Mid Telephoto Focal Length 24.72 39.88 68.02
F-number 2.92 2.92 2.92
Full angle of view 2ω 85.13 56.00 34.31
Image height Y 21.63 21.63 21.63
Lens total length 135.00 147.22 170.64

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 14.3780 30.8700
d12 15.3700 6.9962 1.5000
d20 6.8800 3.2109 0.8100
d27 2.4600 2.5700 1.9000
d29 7.1500 18.4727 33.9716
BF 17.6251 17.5782 17.5747

[Lens group data]
Group Initial surface Focal length
G1 1 120.56
G2 6 -19.16
G3 14 60.42
G4 21 27.89
G5 28 -47.51
G6 30 -576.23
G41 21 36.84
G42 26 92.45
RF1 30 51.66
RR1 32 -41.64

Numerical Example 3
Unit: mm
[Face data]
Surface number rd nd vd
1 397.6900 1.6000 1.94595 17.98
2 183.2800 5.0000 1.48749 70.44
3 -241.3100 0.1500
4 44.3100 7.6300 1.48749 70.44
5 200.0000 (d5)
6* 200.0000 1.4500 1.85135 40.10
7* 20.9400 5.9200
8 -43.9100 0.9000 1.59282 68.62
9 19.6400 5.4200 1.77047 29.74
10 -69.0900 2.5600
11 -23.0700 0.9000 1.49700 81.61
12 -100.8600 (d12)
13(Aperture) ∞ 1.2000
14 48.6900 3.0600 1.69680 55.46
15 -179.5700 0.1500
16 38.0000 6.6900 1.43700 95.10
17 -23.8300 0.8500 1.91082 35.25
18∞ (d18)
19 24.0900 8.3100 1.43700 95.10
20 -31.5800 0.3500
21* -1000.0000 2.8000 1.59201 67.02
22* -41.1200 (d22)
23* 200.0000 1.1500 1.69350 53.20
24* 29.4800 (d24)
25 61.8100 6.8400 1.88300 40.80
26 -45.8100 1.0000 1.53172 48.84
27 79.4400 4.4300
28 -46.9600 1.0000 1.67300 38.26
29 100.0000 (BF)
Image plane ∞

[Aspheric data]
6th 7th 21st 22nd
K 0.00000 -1.00000 0.00000 0.00000
A4 1.65170E-05 3.14480E-05 -4.64340E-05 -1.03570E-05
A6 -6.23420E-08 -8.05320E-08 -7.34270E-08 5.23300E-10
A8 2.51840E-10 1.94400E-09 2.38778E-09 1.82680E-09
A10 -4.49430E-13 -2.18990E-11 -6.59680E-12 -4.24950E-12
A12 2.85710E-16 1.40870E-13 0.00000E+00 0.00000E+00
A14 0.00000E+00 -3.39560E-16 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00
23rd page 24th page
K 0.00000 0.00000
A4 2.56020E-05 2.57690E-05
A6 -2.15850E-07 -2.43820E-07
A8 7.82740E-10 1.07610E-09
A10 0.00000E+00 0.00000E+00
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.35
Wide Angle Mid Telephoto Focal Length 28.81 40.01 67.69
F-number 2.92 2.92 2.92
Full angle of view 2ω 75.92 56.06 33.85
Image height Y 21.63 21.63 21.63
Lens length 120.04 126.08 142.66

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 8.9300 24.1000
d12 12.4600 7.0900 1.5200
d18 7.3300 5.1500 3.1500
d22 2.2700 2.5000 1.9000
d24 7.4900 13.4638 23.0231
BF 19.6292 19.5884 19.6020

[Lens group data]
Group Initial surface Focal length
G1 1 94.26
G2 6 -20.08
G3 14 79.02
G4 19 23.82
G5 23 -50.00
G6 25 -341.49
G41 19 32.76
G42 21 72.36
RF1 25 65.34
RR1 28 -47.35

Numerical Example 4
Unit: mm
[Face data]
Surface number rd nd vd
1 248.5800 1.8000 1.92286 20.88
2 146.1800 6.5500 1.43700 95.10
3 -353.6600 0.1500
4 57.8700 7.6700 1.61997 63.88
5 200.0000 (d5)
6* 140.0000 1.8000 1.85135 40.10
7* 22.6800 7.4100
8 -50.9200 1.0000 1.59282 68.62
9 21.3400 6.6000 1.77047 29.74
10 -86.6500 2.6400
11 -26.9700 0.9000 1.55032 75.50
12 -105.9200 (d12)
13(Aperture) ∞ 1.2000
14 46.6900 3.5400 1.59349 67.00
15 -172.1500 1.6200
16 39.7000 8.8400 1.43700 95.10
17 -25.6700 1.0000 1.91082 35.25
18 -324.4400 (d18)
19 29.3700 7.7000 1.43700 95.10
20 -34.3200 0.3500
21* -1000.0000 2.5000 1.55332 71.68
22* -44.1100 (d22)
23* 939.0000 1.2000 1.69350 53.20
24* 33.2000 (d24)
25 42.2800 5.0700 1.95375 32.32
26 -415.0000 0.6500
27 -216.8300 1.2000 1.59270 35.45
28 31.9600 6.0800
29 -63.9900 1.2000 1.51742 52.15
30∞(BF)
Image plane ∞

[Aspheric data]
6th 7th 21st 22nd
K 0.00000 -1.00000 0.00000 0.00000
A4 1.09500E-05 2.35320E-05 -4.66400E-05 -1.95650E-05
A6 -4.03450E-08 -4.78520E-08 -1.53460E-07 -1.06070E-07
A8 1.00820E-10 8.87380E-10 1.63920E-09 1.34650E-09
A10 1.94880E-13 -1.03180E-11 -2.56090E-12 -1.88290E-12
A12 -1.76500E-15 7.84178E-14 0.00000E+00 0.00000E+00
A14 3.96060E-18 -2.96670E-16 0.00000E+00 0.00000E+00
A16 -2.99700E-21 4.49820E-19 0.00000E+00 0.00000E+00
23rd page 24th page
K 0.00000 0.00000
A4 6.55390E-05 6.85350E-05
A6 -7.34180E-07 -7.54910E-07
A8 4.80150E-09 4.88950E-09
A10 -1.68400E-11 -1.64030E-11
A12 2.50760E-14 2.38980E-14
A14 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.90
Wide Angle Mid Telephoto Focal Length 28.79 49.98 83.51
F-number 2.92 2.92 2.92
Full angle of view 2ω 75.61 45.42 27.77
Image height Y 21.63 21.63 21.63
Lens length 135.02 146.97 164.94

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 16.8200 34.1000
d12 18.0000 7.4500 1.5000
d18 8.0000 4.3300 2.7300
d22 2.2500 2.7200 1.9000
d24 7.5000 17.9506 26.9678
BF 17.6146 17.5433 17.5817

[Lens group data]
Group Initial surface Focal length
G1 1 106.60
G2 6 -22.44
G3 14 70.42
G4 19 27.03
G5 23 -49.65
G6 25 -1002.69
G41 19 37.60
G42 21 83.32
RF1 25 40.46
RR1 27 -32.76

Numerical Example 5
Unit: mm
[Face data]
Surface number rd nd vd
1 500.0000 1.6000 1.94595 17.98
2 205.4700 4.7900 1.48749 70.44
3 -229.9400 0.1500
4 45.2200 7.4900 1.48749 70.44
5 200.0000 (d5)
6* 110.7700 1.4500 1.85135 40.10
7* 19.8700 6.0700
8 -42.4000 0.9000 1.59282 68.62
9 19.0500 5.3700 1.77047 29.74
10 -80.6700 2.7700
11 -22.1700 0.9000 1.49700 81.61
12 -100.0000 (d12)
13(Aperture) ∞ 1.2000
14 44.9400 3.8700 1.69680 55.46
15 -82.6600 0.1500
16 44.7900 6.5600 1.43700 95.10
17 -23.5300 0.8500 1.91082 35.25
18 779.5300 (d18)
19 24.9200 8.2800 1.43700 95.10
20 -30.8600 0.3500
21* -1000.0000 2.4300 1.59201 67.02
22* -45.0500 (d22)
23* 179.6400 1.1500 1.69350 53.20
24* 28.3400 (d24)
25 60.7700 6.1100 1.88300 40.80
26 -54.3400 1.0000 1.62004 36.30
27 96.2900 (d27)
28 -46.6400 1.0000 1.51680 64.20
29 100.0000 (BF)
Image plane ∞

[Aspheric data]
6th 7th 21st 22nd
K 0.00000 -1.00000 0.00000 0.00000
A4 1.70550E-05 3.56250E-05 -4.39970E-05 -1.03710E-05
A6 -6.57480E-08 -8.78860E-08 -1.12110E-07 -5.23190E-08
A8 2.35300E-10 2.31210E-09 2.80750E-09 2.39410E-09
A10 -2.71730E-13 -2.76770E-11 -8.04100E-12 -6.22300E-12
A12 -4.64180E-17 1.84700E-13 0.00000E+00 0.00000E+00
A14 0.00000E+00 -4.54500E-16 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00 0.00000E+00 0.00000E+00
23rd page 24th page
K 0.00000 0.00000
A4 1.77830E-05 1.67490E-05
A6 -1.63200E-07 -1.84270E-07
A8 6.14250E-10 8.30600E-10
A10 0.00000E+00 0.00000E+00
A12 0.00000E+00 0.00000E+00
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.35
Wide Angle Mid Telephoto Focal Length 28.79 40.00 67.69
F-number 2.92 2.92 2.92
Full angle of view 2ω 75.80 55.88 33.85
Image height Y 21.63 21.63 21.63
Lens length 120.00 126.94 144.45

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 9.4400 24.5800
d12 11.9800 6.9500 1.5000
d18 7.6600 5.2900 3.0000
d22 2.2700 2.5000 1.9000
d24 7.5200 13.2500 22.5000
d27 5.0300 5.4900 6.9476
BF 19.6023 19.5788 19.5794

[Lens group data]
Group Initial surface Focal length
G1 1 97.33
G2 6 -19.19
G3 14 63.46
G4 19 24.50
G5 23 -48.67
G6 25 76.44
G7 28 -61.40
G41 19 33.04
G42 21 79.61
GRW 25 -886.35
GRT 25 -1389.51
RF2 25 76.44
RR2 28 -61.40

Numerical Example 6
Unit: mm
[Face data]
Surface number rd nd vd
1 183.6900 1.8000 1.92286 20.88
2 120.2300 6.6500 1.43700 95.10
3 -606.0000 0.1500
4 56.6200 7.7800 1.61997 63.88
5 205.4000 (d5)
6* 116.1800 1.8000 1.85135 40.10
7* 20.9900 7.2300
8 -51.7800 1.0000 1.59282 68.62
9 20.9600 6.3000 1.77047 29.74
10 -91.5400 2.7200
11 -25.8300 0.9000 1.55032 75.50
12 -114.8000 (d12)
13(Aperture) ∞ 1.2000
14 46.3700 3.8000 1.59349 67.00
15 -113.9200 1.1900
16 42.8030 8.7500 1.43700 95.10
17 -24.8400 1.0000 1.91082 35.25
18 -241.5300 (d18)
19 29.7300 7.7000 1.43700 95.10
20 -33.8800 0.3500
21* -1000.0000 2.5000 1.55332 71.68
22* -45.9900 (d22)
23* 1000.0000 1.2000 1.69350 53.20
24* 33.5000 (d24)
25 45.1100 5.5000 1.95375 32.32
26 -246.0000 0.8100
27 ∞ 1.2000 1.56732 42.84
28 31.1200 (d28)
29 -32.7600 1.2000 1.75211 25.05
30 -64.6500 (BF)
Image plane ∞

[Aspheric data]
6th 7th 21st 22nd
K 0.00000 -1.00000 0.00000 0.00000
A4 5.56110E-06 1.90110E-05 -4.38890E-05 -1.70120E-05
A6 -1.43250E-08 -1.83100E-08 -1.09780E-07 -7.76980E-08
A8 2.94330E-11 6.79460E-10 1.25680E-09 1.05710E-09
A10 2.27810E-13 -8.27070E-12 -1.87720E-12 -1.36130E-12
A12 -1.45300E-15 6.60750E-14 0.00000E+00 0.00000E+00
A14 3.27400E-18 -2.63920E-16 0.00000E+00 0.00000E+00
A16 -2.56380E-21 4.23000E-19 0.00000E+00 0.00000E+00
23rd page 24th page
K 0.00000 0.00000
A4 5.16740E-05 5.26540E-05
A6 -6.27980E-07 -6.45670E-07
A8 4.53200E-09 4.71380E-09
A10 -1.78480E-11 -1.83790E-11
A12 3.08590E-14 3.22850E-14
A14 0.00000E+00 0.00000E+00
A16 0.00000E+00 0.00000E+00

[Various data]
Zoom ratio 2.90
Wide Angle Mid Telephoto Focal Length 28.79 50.39 83.39
F-number 2.92 2.92 2.92
Full angle of view 2ω 75.90 44.79 27.76
Image height Y 21.63 21.63 21.63
Lens length 135.01 147.86 164.44

[Variable interval data]
Wide Angle Mid-Telephoto
d5 1.5000 18.5000 33.0000
d12 17.1200 7.3000 1.5000
d18 8.3900 4.6300 2.7800
d22 2.0000 2.4800 1.9000
d24 7.5000 15.7216 25.8069
d26 0.8100 1.5700 1.8000
BF 17.5983 17.5658 17.5615

[Lens group data]
Group Initial surface Focal length
G1 1 102.53
G2 6 -20.59
G3 14 64.27
G4 19 27.36
G5 23 -50.01
G6 25 40.34
G7 27 -32.38
G41 19 37.62
G42 21 87.04
GRW 25 -1006.70
GRT 25 -4248.60
RF2 25 40.34
RR2 27 -32.38

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

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group G7 Seventh lens group GR Rear lens group LF Focusing lens S Aperture stop I Image surface

Claims (11)

The optical system is made up of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a rear lens group GR having a negative refractive power including one or more lens groups. The fifth lens group G5 is made up of a focusing lens LF made up of a negative meniscus lens having a convex surface facing the object side, which moves toward the image surface side when focusing from an object at infinity to an object at a close distance. When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 and the second lens group G2 are moved toward the image surface side. a distance between the second lens group G2 and the third lens group G3 increases, a distance between the third lens group G3 and the fourth lens group G4 decreases, a distance between the fourth lens group G4 and the fifth lens group G5 changes, a distance between the fifth lens group G5 and the rear lens group GR increases, a lens of the rear lens group GR closest to an image surface is fixed with respect to the image surface, the third lens group G3 and the fourth lens group G4 move toward the object side, and the following conditional expression is satisfied:
(1) -3.0<f5/f4<-1.0
(2) 1.0<f3/f4<5.0
Where:
f3: focal length of the third lens group G3 f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5
The optical system is made up of, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a rear lens group GR having negative refractive power including one or more lens groups. The fifth lens group G5 is made up of a focusing lens LF made up of a negative meniscus lens having a convex surface facing the object side, which moves toward the image plane side when focusing from an object at infinity to an object at a close distance. When changing magnification from the wide-angle end to the telephoto end, the first lens group G1 and a distance between the second lens group G2 and the third lens group G3 is decreased, a distance between the third lens group G3 and the fourth lens group G4 is decreased, a distance between the fourth lens group G4 and the fifth lens group G5 is changed, a distance between the fifth lens group G5 and the rear lens group GR is increased, a lens of the rear lens group GR closest to an image surface is fixed with respect to an image surface, and the first lens group G1 moves toward the object side; and the large-aperture zoom lens satisfies the following condition:
(1) -3.0<f5/f4<-1.0
(3) -10.0<f1/f2<-3.0
Where:
f1: focal length of the first lens group G1 f2: focal length of the second lens group G2 f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5
The optical system is made up of, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, a fifth lens group G5 having a negative refractive power, and a rear lens group GR having a negative refractive power including one or more lens groups. The rear lens group GR is made up of two lens groups. The fifth lens group G5 includes a focusing lens LF consisting of a negative meniscus lens having a convex surface facing the object side that moves toward the image plane side when focusing from an object at infinity to an object at a close distance. and, during zooming from the wide-angle end to the telephoto end, a distance between the first lens group G1 and the second lens group G2 increases, a distance between the second lens group G2 and the third lens group G3 decreases, a distance between the third lens group G3 and the fourth lens group G4 decreases, a distance between the fourth lens group G4 and the fifth lens group G5 changes, a distance between the fifth lens group G5 and the rear lens group GR increases, and the distances between the two lens groups increase, and the following conditional expressions are satisfied:
(1) -3.0<f5/f4<-1.0
Where:
f4: focal length of the fourth lens group G4 f5: focal length of the fifth lens group G5
3. The large-aperture zoom lens according to claim 1, wherein the rear lens group GR is composed of one lens group, the rear lens group GR being composed of, in order from the object side, a lens unit RF1 having positive refractive power and a lens unit RR1 having negative refractive power, the lens unit RF1 having at least a positive lens with a convex surface facing the object side, the lens unit RR1 having at least one negative lens, the lens unit RR1 having at least one negative lens, the lens unit RR1 having at least one negative lens, the lens unit GR satisfying the following conditional expression:
(9) -2.0<fRF1/fRR1<0.0
Where:
fRF1: focal length of lens unit RF1 fRR1: focal length of lens unit RR1
4. The large-aperture zoom lens according to claim 3 , wherein the lens in the rear lens group GR located closest to the image plane is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end.
6. The large-aperture zoom lens according to claim 3, wherein the two lens groups of the rear lens group GR are, in order from the object side, a lens group RF2 having positive refractive power and a lens group RR2 having negative refractive power, the lens group RF2 has at least a positive lens with a convex surface facing the object side, which is closest to the object side , and the lens group RR2 has at least one negative lens closest to the image side, and the following conditional expression is satisfied:
(10) -2.0<fRF2/fRR2<0.0
(11) 0.5<RWD/RTD<1.0
Where:
fRF2: focal length of lens group RF2 fRR2: focal length of lens group RR2 RWD: composite thickness on the optical axis of the rear lens group GR at the wide-angle end RTD: composite thickness on the optical axis of the rear lens group GR at the telephoto end
7. The large-aperture zoom lens according to claim 2 , wherein the third lens group G3 and the fourth lens group G4 move toward the object side during zooming from the wide-angle end to the telephoto end, and the following conditional expression is satisfied:
(2) 1.0<f3/f4<5.0
Where:
f3: focal length of the third lens group G3 f4: focal length of the fourth lens group G4
8. The large-aperture zoom lens according to claim 1 , wherein the first lens group G1 moves toward the object side during zooming from the wide-angle end to the telephoto end, and the following condition is satisfied:
(3) -10.0<f1/f2<-3.0
Where:
f1: focal length of the first lens group G1 f2: focal length of the second lens group G2
9. The large-aperture zoom lens according to claim 1, wherein the first lens group G1 comprises, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a positive lens L12 having a convex surface facing the object side, and a positive lens L13 having a convex surface facing the object side, and satisfies the following conditional expression:
(4) νd1n<30.0
(5) 65.0<νd1p
(6) 3.0<νd1p/νd1n
Where:
νd1n: Abbe number of the negative meniscus lens L11, and νd1p: Abbe number of the positive lens having the lowest dispersion among the positive lens L12 and the positive lens L13.
10. The large-aperture zoom lens according to claim 1, wherein the fourth lens group G4 is composed of, in order from the object side, a lens group G41 having at least one positive lens and having positive refractive power as a whole, and a positive lens G42 having an aspheric surface, and wherein the following conditional expression is satisfied:
(7) 0.3<f41/f42<0.6
Where:
f41: focal length of lens group G41 f42: focal length of positive lens G42
11. The large-aperture zoom lens according to claim 1 , wherein the following condition is satisfied:
(8) -0.3<1/fRW<0.0
Where:
fRW: focal length of the rear lens group GR at the wide-angle end [mm]

Images