JP7501339B2 - Optical system, optical device, and method for manufacturing optical system - Google Patents

Description

The present invention relates to an optical system, an optical device, and a method for manufacturing an optical system.

Conventionally, optical systems have been proposed for use in optical devices such as photo cameras, electronic still cameras, and video cameras (see, for example, Patent Document 1).

International Publication No. 2013/027364

The optical system disclosed herein has multiple focusing groups, each of which moves along the optical axis on a different trajectory during focusing, and satisfies the following conditional expression when focusing on an object at infinity in the telephoto end state.
4.00 < Σ|γi| × (5.76/Fnot) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of the multiple focusing groups. Fnot: F-number in the telephoto end state of the optical system.

The manufacturing method of the optical system disclosed herein arranges multiple focusing groups so that, during focusing, the multiple focusing groups move along the optical axis on different trajectories, and when focusing on an object at infinity in the telephoto end state, the following conditional expression is satisfied:
4.00 < Σ|γi| × (5.76/Fnot) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of the multiple focusing groups. Fnot: F-number in the telephoto end state of the optical system.

1A is a cross-sectional view of the optical system of the first embodiment when focusing on an object at infinity in the wide-angle end state, and FIG. 1B is a cross-sectional view of the optical system of the first embodiment when focusing on an object at infinity in the telephoto end state. 1A is a diagram showing various aberrations of the optical system of Example 1 when focusing on an object at infinity in the wide-angle end state, FIG. 1B is a diagram showing various aberrations of the optical system of Example 1 when focusing on a close object in the wide-angle end state, FIG. 1C is a diagram showing various aberrations of the optical system of Example 1 when focusing on an object at infinity in the telephoto end state, and FIG. 1D is a diagram showing various aberrations of the optical system of Example 1 when focusing on a close object in the telephoto end state. 1A is a cross-sectional view of the optical system of the second embodiment when focused on an object at infinity in the wide-angle end state, and FIG. 1B is a cross-sectional view of the optical system of the second embodiment when focused on an object at infinity in the telephoto end state. 1A is a diagram showing various aberrations of the optical system of Example 2 when focusing on an object at infinity in the wide-angle end state, FIG. 1B is a diagram showing various aberrations of the optical system of Example 2 when focusing on a close object in the wide-angle end state, FIG. 1C is a diagram showing various aberrations of the optical system of Example 2 when focusing on an object at infinity in the telephoto end state, and FIG. 1D is a diagram showing various aberrations of the optical system of Example 2 when focusing on a close object in the telephoto end state. 1A is a cross-sectional view of the optical system of the third embodiment when focused on an object at infinity in the wide-angle end state, and FIG. 1B is a cross-sectional view of the optical system of the third embodiment when focused on an object at infinity in the telephoto end state. 1A is a diagram showing various aberrations of the optical system of Example 3 when focusing on an object at infinity in the wide-angle end state, FIG. 1B is a diagram showing various aberrations of the optical system of Example 3 when focusing on a close object in the wide-angle end state, FIG. 1C is a diagram showing various aberrations of the optical system of Example 3 when focusing on an object at infinity in the telephoto end state, and FIG. 1D is a diagram showing various aberrations of the optical system of Example 3 when focusing on a close object in the telephoto end state. FIG. 13 is a cross-sectional view of the optical system of the fourth embodiment when focusing on an object at infinity in the telephoto end state. 13A is a diagram showing various aberrations of the optical system of Example 4 when focusing on an object at infinity in the telephoto end state, and FIG. 13B is a diagram showing various aberrations of the optical system of Example 4 when focusing on a close object in the telephoto end state. FIG. 1 is a schematic diagram of a camera equipped with the optical system of the present embodiment. 1 is a flowchart outlining a method for manufacturing an optical system according to the present embodiment.

The following describes the optical system, optical device, and method for manufacturing the optical system according to the embodiments of the present application.

The optical system of this embodiment has multiple focusing groups, and during focusing, the multiple focusing groups move along the optical axis on different trajectories, and when focusing on an object at infinity in the telephoto end state, the following conditional expression is satisfied: Note that in this disclosure, the telephoto end state of a single-focus optical system with a fixed focal length refers to a state in which the focal length of the optical system is that focal length.
(1) 4.00 < Σ | γ i | × (5.76 / F not ) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of the multiple focusing groups. Fnot: F-number in the telephoto end state of the optical system.

In the optical system of this embodiment, multiple focusing groups each move along a different trajectory along the optical axis, suppressing aberration fluctuations that occur during focusing and achieving good optical performance from infinity to close distances.

In addition, the optical system of this embodiment enables highly accurate focus control by making the value of conditional expression (1) smaller than the upper limit.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional formula (1) to 10.00. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional formula (1) to 9.50, 9.00, 8.50, 8.00, 7.50, 7.00, 6.80, 6.60, or even 6.50.

In addition, by making the value of conditional expression (1) greater than the lower limit, the optical system of this embodiment can reduce the amount of movement of the focusing lens group during focusing, thereby shortening the time required for focusing.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional formula (1) to 4.00. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional formula (1) to 4.50, 4.80, 5.00, 5.30, 5.50, 5.80, 6.00, 6.10, or even 6.20.

The above configuration makes it possible to realize an optical system with good optical performance.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression when focusing on an object at infinity in the telephoto end state.
(2) 0.10 < |γ|max/|γ|min < 10.00
however,
|γ|max: the maximum absolute value of the image plane transfer coefficients of the multiple focusing groups. |γ|min: the minimum absolute value of the image plane transfer coefficients of the multiple focusing groups.

The optical system of this embodiment satisfies conditional expression (2), so that the amount of movement of the focusing group with a smaller absolute value of the image plane movement coefficient in accordance with the movement of the focusing group with a larger absolute value of the image plane movement coefficient during focusing falls within an appropriate range, making it easier to control the movement of the focusing group.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (2) to 10.00. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (2) to 9.50, 9.00, 8.50, 8.00, 7.50, 7.00, 6.50, 6.00, 5.50, 5.00, or even 4.50.

In addition, in the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (2) to 0.10. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (1) to 0.50, 1.00, 1.50, 2.00, 2.30, 2.50, or even 2.80.

In addition, in the optical system of this embodiment, it is preferable that at least two of the multiple focusing groups have negative refractive power.

By having such a configuration, the optical system of this embodiment can suppress fluctuations in the image plane and spherical aberration during focusing.

In addition, in the optical system of this embodiment, it is preferable that at least two focusing groups are arranged adjacent to each other.

By having such a configuration, the optical system of this embodiment does not require complex arrangement of the components that move the focusing group, and the optical system can be made compact.

In addition, in the optical system of this embodiment, when focusing from an object at infinity to an object at a close distance, it is preferable that at least two of the multiple focusing groups move toward the image side.

The optical system of this embodiment has such a configuration that it is possible to suppress image plane fluctuations during focusing.

In addition, in the optical system of this embodiment, it is preferable that at least two of the multiple focusing groups each have at least one positive lens and at least one negative lens.

By having such a configuration, the optical system of this embodiment can suppress fluctuations in axial chromatic aberration during focusing.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(3) 2.20° < ωt < 13.00°
however,
ωt: Half angle of view in the telephoto end state of the optical system

In the optical system of this embodiment, the image plane can be effectively corrected by making the value of conditional expression (3) smaller than the upper limit.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (3) to 13.00°. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (3) to 12.00°, 10.00°, 8.50°, 7.00°, 6.00°, 5.50°, 5.00°, 4.50°, 4.00°, or even 3.50°.

In addition, in the optical system of this embodiment, an appropriate amount of image plane correction can be ensured by making the value of conditional expression (3) greater than the lower limit.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (3) to 2.20°. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (3) to 2.40°, 2.50°, 2.65°, 2.80°, or even 3.00°.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(4) 0.40 < TLt / ft < 0.90
however,
TLt: Total optical length of the optical system in the telephoto end state ft: Focal length of the entire optical system in the telephoto end state

In the optical system of this embodiment, the optical system can be made compact by making the value of conditional expression (4) smaller than the upper limit.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (4) to 0.90. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (4) to 0.88, 0.85, 0.83, 0.80, 0.78, or even 0.75.

In addition, the optical system of this embodiment can appropriately correct various aberrations by making the value of conditional expression (4) greater than the lower limit.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (4) to 0.40. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (4) to 0.45, 0.50, 0.55, 0.60, 0.63, 0.65, 0.68, 0.70, or even 0.72.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(5) 4.00 < Σ | γ i | × (5.76 / F not ) × ( Y max / 21.63 ) < 10.00
however,
Ymax: Maximum image height

In the optical system of this embodiment, by making the value of conditional expression (5) smaller than the upper limit, highly accurate focusing control is possible.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (5) to 10.00. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (5) to 9.50, 9.00, 8.50, 8.00, 7.50, 7.00, 6.80, 6.60, or even 6.50.

In addition, in the optical system of this embodiment, by making the value of conditional expression (5) greater than the lower limit, the amount of movement of the focusing lens group during focusing can be reduced, and the time required for focusing can be shortened.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (5) to 4.00. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (5) to 4.50, 4.80, 5.00, 5.30, 5.50, 5.80, 6.00, 6.10, or even 6.20.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(6) 2.00 < (-fF1) / FD
however,
fF1: focal length of the focusing group arranged closest to the object among the multiple focusing groups FD: distance on the optical axis between the focusing group arranged closest to the object among the multiple focusing groups and the focusing group arranged closest to the image among the multiple focusing groups when focusing at infinity in the telephoto end state

By satisfying conditional expression (6), the optical system of this embodiment reduces the variation in the height of the paraxial chief ray in each focusing group, which reduces the range of aberration variation associated with movement of the focusing group, making it possible to appropriately suppress aberration variation during focusing.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (6) to 2.00. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (6) to 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, or even 8.50.

In the optical system of this embodiment, if the upper limit value of conditional expression (6) is set to 500.00, the effect of this embodiment can be more reliably achieved. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit value of conditional expression (6) to 400.00, 300.00, 200.00, 100.00, 75.00, 50.00, or even 25.00.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(7) 0.30 < fF1/fF2 < 1.00
however,
fF1: focal length of the focusing group arranged closest to the object among the multiple focusing groups; fF2: focal length of the focusing group arranged second closest to the object among the multiple focusing groups.

In the optical system of this embodiment, by making the value of conditional expression (7) smaller than the upper limit, highly accurate focusing control is possible.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (7) to 1.00. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (7) to 0.95, 0.90, 0.88, 0.85, 0.83, or even 0.80.

In addition, in the optical system of this embodiment, by making the value of conditional expression (7) greater than the lower limit, the amount of movement of the focusing lens group during focusing can be reduced, and the time required for focusing can be shortened.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (7) to 0.30. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (7) to 0.35, 0.40, 0.43, 0.45, 0.48, 0.50, or even 0.52.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(8) 0.85 < βF1/βF2 < 1.40
however,
βF1: Lateral magnification of the focusing group arranged closest to the object among the plurality of focusing groups βF2: Lateral magnification of the focusing group arranged second from the object among the plurality of focusing groups

In the optical system of this embodiment, by making the value of conditional expression (8) smaller than the upper limit, highly accurate focusing control is possible.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (8) to 1.40. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (8) to 1.38, 1.35, 1.33, 1.30, 1.28, 1.26, or even 1.24.

In addition, in the optical system of this embodiment, by making the value of conditional expression (8) greater than the lower limit, the amount of movement of the focusing lens group during focusing can be reduced, and the time required for focusing can be shortened.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (8) to 0.85. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (8) to 0.88, 0.90, 0.93, 0.95, 0.98, or even 1.00.

In addition, in the optical system of this embodiment, it is preferable to have an anti-vibration group that performs image stabilization by moving in a direction perpendicular to the optical axis, closer to the object than the multiple focusing groups.

By having such a configuration, the optical system of this embodiment can suppress the impact of the focusing operation on the vibration reduction function.

In addition, in the optical system of this embodiment, it is preferable that the lens group arranged on the object side adjacent to the focusing group arranged closest to the object side among the multiple focusing groups has an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis.

By having such a configuration, the optical system of this embodiment can suppress the impact of the focusing operation on the vibration reduction function.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(9) 0.10 < fvr / ft < 0.30
however,
fvr: focal length of the vibration reduction group ft: focal length of the entire optical system in the telephoto end state

In the optical system of this embodiment, by making the value of conditional expression (9) smaller than the upper limit, the amount of movement required for vibration reduction does not become too large, and the optical system can be made compact.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (9) to 0.30. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (9) to 0.28, 0.25, or even 0.23.

In the optical system of this embodiment, by making the value of conditional expression (9) greater than the lower limit, it is possible to suppress aberration fluctuations due to image stabilization.

In addition, in the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (9) to 0.10. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (9) to 0.13, 0.15, 0.18, or even 0.20.

The optical system of this embodiment is composed of, in order from the object side, a front group having positive refractive power, a first intermediate group having negative refractive power, a second intermediate group having positive refractive power, and a rear group having at least one lens group and negative refractive power, and it is preferable that the spacing between each group changes when the magnification is changed and that the rear group has multiple focusing lens groups.

The optical system of this embodiment has such a configuration that it has a so-called double telephoto configuration at the telephoto end, which allows the optical system to be made compact. Also, the optical system of this embodiment has such a configuration that the amount of movement of the focusing group during focusing can be made large, allowing the minimum shooting distance to be shortened.

In addition, in the optical system of this embodiment, the front group has two lens groups with positive refractive power, and it is preferable that the distance between the two lens groups changes when the magnification is changed.

In addition, it is preferable that the optical system of this embodiment has a positive lens group having positive refractive power adjacent to the focusing group located closest to the object.

The optical system of this embodiment has such a configuration that the positive lens group and the focusing group arranged closest to the object form a telephoto configuration, making it possible to miniaturize the optical system.

Moreover, it is preferable that the optical system of this embodiment satisfies the following conditional expression.
(10) 2.00 < ft/fw < 20.00
however,
ft: focal length of the entire optical system in the telephoto end state fw: focal length of the entire optical system in the wide-angle end state

In the optical system of this embodiment, by making the value of conditional expression (10) smaller than the upper limit, it is possible to suppress aberration fluctuations caused by magnification changes.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (10) to 20.00. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (10) to 17.50, 15.00, 13.00, 10.00, 9.00, 8.00, 7.00, 6.00, 5.00, 4.50, or even 4.00.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (10) to 2.00. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (10) to 2.30, 2.50, 2.80, 3.00, 3.30, 3.50, or even 3.65.

In the optical system of this embodiment, it is preferable that the groups that move during magnification variation are, in order from the object side, the first moving group, the second moving group, and the third moving group, and that the following conditional expression is satisfied:
(11) 0.10 < - (MV1 + MV2 + MV3) / TLt < 0.30
however,
MV1: Amount of movement in the optical axis direction of the first moving group when changing magnification, with the image surface side of the first moving group being positive. MV2: Amount of movement in the optical axis direction of the second moving group when changing magnification, with the image surface side of the second moving group being positive. MV3: Amount of movement in the optical axis direction of the third moving group when changing magnification, with the image surface side of the third moving group being positive. TLt: Total optical length of the optical system in the telephoto end state.

By satisfying conditional expression (11), the optical system of this embodiment can reduce the movement of the center of gravity when changing the magnification.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the upper limit value of conditional expression (11) to 0.30. In order to make the effect of this embodiment more certain, it is preferable to set the upper limit value of conditional expression (11) to 0.28, 0.25, 0.23, 0.20, 0.18, or even 0.16.

In the optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (11) to 0.10. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (11) to 0.12, and more preferably 0.14.

In addition, in the optical system of this embodiment, when focusing on an object at infinity, it is preferable that the multiple focusing lens groups move monotonically toward the object side when changing magnification from the wide-angle end state to the telephoto end state.

By having such a configuration, the optical system of this embodiment does not complicate the control of the movement of the focusing group when changing the magnification, and can improve focusing accuracy.

In addition, in the optical system of this embodiment, it is preferable that the number of focusing groups is two.

By having such a configuration, the optical system of this embodiment does not require complex arrangement of the components that move the focusing group, and the optical system can be made compact.

The above configuration makes it possible to realize an optical system that is compact and has good imaging performance.

The optical device of this embodiment has an optical system with the above-mentioned configuration. This makes it possible to realize an optical device with good optical performance.

The manufacturing method of the optical system of the present embodiment is a manufacturing method of an optical system in which multiple focusing groups are arranged so that, during focusing, each of the multiple focusing groups moves along the optical axis in a different trajectory, and when focusing on an object at infinity in the telephoto end state, the following conditional expression is satisfied:
(1) 4.00 < Σ | γ i | × (5.76 / F not ) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of the multiple focusing groups. Fnot: F-number in the telephoto end state of the optical system.

This method of manufacturing an optical system makes it possible to manufacture an optical system with good optical performance.

(Numerical Example)
Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1A is a cross-sectional view of the optical system of the first embodiment when focused on an object at infinity in the wide-angle end state, and FIG. 1B is a cross-sectional view of the optical system of the first embodiment when focused on an object at infinity in the telephoto end state.

The optical system of this embodiment has, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

The first lens group G1 consists of, from the object side, a biconvex positive lens L1 and a plano-convex lens L2 with its convex surface facing the object side.

The second lens group G2 consists of, from the object side, a cemented negative lens consisting of a biconvex positive lens L3 and a biconcave negative lens L4, and a biconvex positive lens L5.

The third lens group G3 consists of, in order from the object side, a cemented negative lens of a biconvex positive lens L6 and a biconcave negative lens L7, a cemented negative lens of a biconcave negative lens L8 and a positive meniscus lens L9 with its convex surface facing the object side, and a biconcave negative lens L10.

The fourth lens group G4 consists of, in order from the object side, a biconvex positive lens L11, a plano-convex lens L12 with a convex surface facing the object side, a plano-convex lens L13 with a convex surface facing the object side, a biconcave negative lens L14, an aperture stop S, a positive meniscus lens L15 with a convex surface facing the image side, a negative meniscus lens L16 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with a convex surface facing the image side, and a positive meniscus lens L19 with a convex surface facing the object side.

The fifth lens group G5 is made up of a cemented negative lens consisting of a biconvex positive lens L20 and a biconcave negative lens L21.

The sixth lens group G6 consists of, from the object side, a biconvex positive lens L22 and a biconcave negative lens L23.

The seventh lens group G7 consists of, from the object side, a biconcave negative lens L24 and a positive meniscus lens L25 with its convex surface facing the object side.

An image sensor (not shown) composed of a CCD or CMOS or the like is disposed on the image plane I.

A filter FL is placed between the optical system of this embodiment and the image plane I.

The optical system of this embodiment focuses by moving the fifth lens group G5 and the sixth lens group G6, which is disposed adjacent to the fifth lens group, along the optical axis. When focusing on a close object from a state focused on infinity, the fifth lens group G5 and the sixth lens group G6 are moved from the object side to the image side along different trajectories.

In the optical system of this embodiment, among the lenses in the fourth lens group G4, the cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with its convex surface facing the image side is configured as an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis.

In the optical system of this embodiment, the first lens group G1 and the second lens group G2 correspond to the front group, the third lens group G3 corresponds to the first intermediate group, the fourth lens group G4 corresponds to the second intermediate group, and the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7 correspond to the rear group. The fifth lens group G5 corresponds to the focusing group arranged closest to the object, and the fourth lens group G4 corresponds to a positive lens group having positive refractive power adjacent to the focusing group arranged closest to the object. The first lens group G1, the third lens group G3 and the fourth lens group G4 correspond to the first moving group, the second moving group and the third moving group, respectively.

The values of the optical system specifications in this embodiment are shown in Table 1 below. In Table 1, ft is the focal length of the optical system when focused on infinity in the telephoto end state, fw is the focal length of the optical system when focused on infinity in the wide-angle end state, Fnot is the F-number of the optical system when focused on infinity in the telephoto end state, TLt is the total optical length of the optical system when focused on infinity in the telephoto end state, Bf is the back focus of the optical system, and ωt is the half angle of view of the optical system in the telephoto end state.

In [Lens specifications], m indicates the order of the optical surface counted from the object side, r indicates the radius of curvature, d indicates the surface spacing, and nd indicates the refractive index for the d line (wavelength 587.6 nm). Also, in [Lens specifications], the radius of curvature r=∞ indicates a flat surface.

The focal length ft, radius of curvature r and other length units listed in Table 1 are in "mm". However, this is not limited to this because the optical system can achieve the same optical performance even if it is proportionally enlarged or reduced.

The symbols in Table 1 described above will also be used in the tables of other examples described below.

(Table 1)
[Overall specifications]
ft 388.17
fw103.09
Fnot 5.76
TLt 284.55
Image height 21.70
ωt 3.10°

[Lens specifications]
mrd nd
1) 464.984 3.830 1.487490
2) -464.984 0.150
3) 178.061 4.560 1.437001
4) ∞ D4
5) 63.221 7.030 1.497820
6) -658.500 1.000 1.804400
7) 57.457 1.530
8) 56.530 7.420 1.437001
9) -447.440 D9
10) 137.036 6.110 1.720467
11) -67.293 1.300 1.497820
12) 47.996 5.730
13) -84.272 1.200 1.741000
14) 49.681 3.410 1.854505
15) 447.567 3.150
16) -60.243 1.200 1.755000
17) 218.520 D17
18) 152.668 3.220 1.593190
19) -152.668 0.150
20) 64.555 3.690 1.497820
21) ∞ 0.450
22) 48.227 4.340 1.497820
23) ∞ 2.420
24) -93.779 1.650 1.806100
25) 1675.249 2.800
26>∞ 11.710 (aperture stop)
27) -125.942 2.310 1.808090
28) -60.541 0.600
29) 134.570 1.400 2.000690
30) 34.633 2.730
31) 59.403 5.160 1.552981
32) -38.045 1.250 1.953750
33) -67.886 0.660
34) 35.224 3.500 1.603420
35) 140.226 D35
36) 120.647 2.260 1.850260
37) -120.465 1.000 1.729160
38) 35.481 D38
39) 560.475 2.630 1.654115
40) -50.042 2.310
41) -44.883 1.000 1.902650
42) 660.951 D42
43) -285.763 1.000 1.497820
44) 43.194 1.460
45) 47.384 5.670 1.738000
46) 1194.653 29.620
47) ∞ 1.600 1.516800
48) ∞ 0.000

[Focal length data for each group]
Group Initial surface Focal length
G1 1 220.226
G2 5 412.716
G3 10 -37.713
G4 18 45.972
G5 36 -81.740
G6 39 -153.334
G7 43 502.735

[Variable interval data]
When focusing at infinity When focusing on a close-up object Telephoto end Wide-angle end Telephoto end Wide-angle end
D4 51.500 1.500 51.500 1.500
D9 25.600 1.300 25.600 1.300
D17 2.100 43.095 2.100 43.095
D35 3.467 3.200 34.084 4.590
D38 8.800 14.300 9.182 22.618
D42 48.913 26.984 17.915 17.275

Figure 2(a) is a diagram of various aberrations of the optical system of the first embodiment when focusing on an object at infinity in the wide-angle end state, Figure 2(b) is a diagram of various aberrations of the optical system of the first embodiment when focusing on a close object in the wide-angle end state, Figure 2(c) is a diagram of various aberrations of the optical system of the first embodiment when focusing on an object at infinity in the telephoto end state, and Figure 2(d) is a diagram of various aberrations of the optical system of the first embodiment when focusing on a close object in the telephoto end state.

In each aberration diagram, FNO indicates the F-number and Y indicates the image height. In detail, the spherical aberration diagram indicates the F-number value corresponding to the maximum aperture, the astigmatism diagram and distortion diagram indicate the maximum image height, and the coma diagram indicates the value of each image height. d indicates the d-line and g indicates the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane and the dashed line indicates the meridional image plane. The same symbols as those used in the various aberration diagrams of the present embodiment are used in the various aberration diagrams of other embodiments described later.

From each aberration diagram, it can be seen that the optical system of this embodiment effectively suppresses aberration fluctuations during focusing and zooming, and has high optical performance.

Second Example
FIG. 3A is a cross-sectional view of the optical system of the second embodiment when focused on an object at infinity in the wide-angle end state, and FIG. 3B is a cross-sectional view of the optical system of the second embodiment when focused on an object at infinity in the telephoto end state.

The optical system of this embodiment has, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

The first lens group G1 consists of, from the object side, a biconvex positive lens L1 and a positive meniscus lens L2 with its convex surface facing the object side.

The second lens group G2 consists of, from the object side, a cemented negative lens consisting of a biconvex positive lens L3 and a biconcave negative lens L4, and a biconvex positive lens L5.

The third lens group G3 consists of, in order from the object side, a cemented negative lens of a biconvex positive lens L6 and a biconcave negative lens L7, a cemented negative lens of a biconcave negative lens L8 and a positive meniscus lens L9 with its convex surface facing the object side, and a biconcave negative lens L10.

The fourth lens group G4 consists of a biconvex positive lens L11, a biconvex positive lens L12, a positive meniscus lens L13 with its convex surface facing the object side, a biconcave negative lens L14, an aperture stop S, a positive meniscus lens L15 with its convex surface facing the image side, a negative meniscus lens L16 with its convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with its convex surface facing the image side, and a positive meniscus lens L19 with its convex surface facing the object side.

The fifth lens group G5 is made up of a cemented negative lens consisting of a biconvex positive lens L20 and a biconcave negative lens L21.

The sixth lens group G6 consists of, from the object side, a biconvex positive lens L22 and a biconcave negative lens L23.

The seventh lens group G7 consists of, from the object side, a biconvex positive lens L24 and a biconcave negative lens L25.

An image sensor (not shown) composed of a CCD or CMOS or the like is disposed on the image plane I.

A filter FL is placed between the optical system of this embodiment and the image plane I.

The optical system of this embodiment focuses by moving the fifth lens group G5 and the sixth lens group G6, which is disposed adjacent to the fifth lens group, along the optical axis. When focusing on a close object from a state focused on infinity, the fifth lens group G5 and the sixth lens group G6 are moved from the object side to the image side along different trajectories.

In the optical system of this embodiment, among the lenses in the fourth lens group G4, the cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with its convex surface facing the image side is configured as an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis.

In the optical system of this embodiment, the first lens group G1 and the second lens group G2 correspond to the front group, the third lens group G3 corresponds to the first intermediate group, the fourth lens group G4 corresponds to the second intermediate group, and the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7 correspond to the rear group. The fifth lens group G5 corresponds to the focusing group arranged closest to the object, and the fourth lens group G4 corresponds to a positive lens group having positive refractive power adjacent to the focusing group arranged closest to the object. The first lens group G1, the third lens group G3 and the fourth lens group G4 correspond to the first moving group, the second moving group and the third moving group, respectively.

The specifications of the optical system in this embodiment are shown in Table 2 below.

(Table 2)
[Overall specifications]
ft 388.00
fw 103.00
Fnot 5.78
TLt 282.75
Image height 21.70
ωt 3.12°

[Lens specifications]
mrd nd
1) 461.498 4.044 1.487490
2) -484.081 0.150
3) 162.155 5.612 1.433848
4) 10534.017 D4
5) 62.380 7.398 1.497820
6) -731.970 1.800 1.804400
7) 54.132 1.556
8) 53.257 7.554 1.437001
9) -464.724 D9
10) 132.170 5.223 1.720467
11) -65.493 1.300 1.497820
12) 43.845 5.392
13) -91.249 1.200 1.741000
14) 50.773 3.298 1.854510
15) 638.237 3.281
16) -51.814 1.200 1.755000
17) 266.599 D17
18) 142.493 3.606 1.593190
19) -123.344 0.150
20) 60.505 4.108 1.497820
21) -568.819 0.150
22) 44.989 4.011 1.497820
23) 245.839 2.588
24) -123.050 1.600 1.903660
25) 232.838 2.499
26> ∞ 11.254 (aperture stop)
27) -209.945 2.294 1.808090
28) -74.983 0.200
29) 88.381 1.200 2.000690
30) 35.868 2.796
31) 59.704 5.455 1.552981
32) -38.761 1.000 1.953750
33) -68.451 1.000
34) 36.306 2.591 1.667550
35) 73.629 D35
36) 169.847 3.056 1.806099
37) -40.066 1.100 1.743200
38) 35.929 D38
39) 79.209 3.479 1.654115
40) -42.092 2.063
41) -37.678 1.000 1.902650
42) 90.347 D42
43) 71.521 4.993 1.737999
44) -273.127 1.225
45) -279.754 1.400 1.497820
46) 76.508 31.411
47) ∞ 1.600 1.516800
48) ∞ 0.00

[Focal length data for each group]
Group Initial surface Focal length
G1 1 213.348
G2 5 450.523
G3 10 -36.240
G4 18 44.353
G5 36 -70.754
G6 39 -122.307
G7 43 196.088

[Variable interval data]
When focusing at infinity When focusing on a close-up object Telephoto end Wide-angle end Telephoto end Wide-angle end
D4 51.250 1.500 51.250 1.500
D9 24.478 1.500 24.478 1.500
D17 1.500 40.982 1.500 40.982
D35 6.809 4.262 37.809 5.987
D38 3.836 9.336 3.836 14.351
D42 47.972 28.511 16.969 21.771

Figure 4(a) is a diagram of various aberrations of the optical system of the second embodiment when focusing on an object at infinity in the wide-angle end state, Figure 4(b) is a diagram of various aberrations of the optical system of the second embodiment when focusing on a close object in the wide-angle end state, Figure 4(c) is a diagram of various aberrations of the optical system of the second embodiment when focusing on an object at infinity in the telephoto end state, and Figure 4(d) is a diagram of various aberrations of the optical system of the second embodiment when focusing on a close object in the telephoto end state.

From each aberration diagram, it can be seen that the optical system of this embodiment effectively suppresses aberration fluctuations during focusing and zooming, and has high optical performance.

(Third Example)
FIG. 5A is a cross-sectional view of the optical system of the third embodiment when focused on an object at infinity in the wide-angle end state, and FIG. 5B is a cross-sectional view of the optical system of the third embodiment when focused on an object at infinity in the telephoto end state.

The optical system of this embodiment has, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

The first lens group G1 consists of, from the object side, a biconvex positive lens L1 and a plano-convex lens L2 with its convex surface facing the object side.

The second lens group G2 consists of, from the object side, a cemented negative lens consisting of a biconvex positive lens L3 and a biconcave negative lens L4, and a biconvex positive lens L5.

The third lens group G3 consists of, in order from the object side, a cemented negative lens of a biconvex positive lens L6 and a biconcave negative lens L7, a cemented negative lens of a biconcave negative lens L8 and a positive meniscus lens L9 with its convex surface facing the object side, and a biconcave negative lens L10.

The fourth lens group G4 consists of, in order from the object side, a biconvex positive lens L11, a plano-convex lens L12 with a convex surface facing the object side, a plano-convex lens L13 with a convex surface facing the object side, a biconcave negative lens L14, an aperture stop S, a positive meniscus lens L15 with a convex surface facing the image side, a negative meniscus lens L16 with a convex surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with a convex surface facing the image side, and a positive meniscus lens L19 with a convex surface facing the object side.

The fifth lens group G5 consists of a negative meniscus lens L20 with its convex surface facing the object side.

The sixth lens group G6 consists of, from the object side, a biconvex positive lens L21 and a biconcave negative lens L22.

The seventh lens group G7 consists of, from the object side, a negative biconcave lens L23 and a positive meniscus lens L24 with its convex surface facing the object side.

An image sensor (not shown) composed of a CCD or CMOS or the like is disposed on the image plane I.

A filter FL is placed between the optical system of this embodiment and the image plane I.

The optical system of this embodiment focuses by moving the fifth lens group G5 and the sixth lens group G6, which is disposed adjacent to the fifth lens group, along the optical axis. When focusing on a close object from a state focused on infinity, the fifth lens group G5 and the sixth lens group G6 are moved from the object side to the image side along different trajectories.

In the optical system of this embodiment, among the lenses in the fourth lens group G4, the cemented positive lens consisting of a biconvex positive lens L17 and a negative meniscus lens L18 with its convex surface facing the image side is configured as an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis.

In the optical system of this embodiment, the first lens group G1 and the second lens group G2 correspond to the front group, the third lens group G3 corresponds to the first intermediate group, the fourth lens group G4 corresponds to the second intermediate group, and the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7 correspond to the rear group. The fifth lens group G5 corresponds to the focusing group arranged closest to the object, and the fourth lens group G4 corresponds to a positive lens group having positive refractive power adjacent to the focusing group arranged closest to the object. The first lens group G1, the third lens group G3 and the fourth lens group G4 correspond to the first moving group, the second moving group and the third moving group, respectively.

The values of the optical system in this embodiment are listed in Table 3 below.

(Table 3)
[Overall specifications]
ft 388.17
fw103.09
Fnot 5.76
TLt 284.55
Image height 21.70
ωt 3.10°

[Lens specifications]
mrd nd
1) 473.392 3.775 1.487490
2) -473.392 0.150
3) 173.647 4.644 1.437001
4) ∞ D4
5) 62.855 7.078 1.497820
6) -651.889 1.000 1.804400
7) 56.515 1.403
8) 54.206 7.436 1.437001
9) -623.807 D9
10) 128.315 6.000 1.720467
11) -64.259 1.300 1.497820
12) 45.968 5.061
13) -208.553 1.200 1.741000
14) 46.792 3.257 1.854505
15) 199.693 4.012
16) -45.395 1.200 1.755000
17) 255.243 D17
18) 134.472 3.430 1.593190
19) -134.472 0.150
20) 72.925 3.357 1.497820
21) ∞ 0.450
22) 50.062 4.141 1.497820
23) ∞ 2.571
24) -83.092 1.650 1.806099
25) 1670.548 2.071
26> ∞ 12.429 (aperture stop)
27) -192.026 2.566 1.808090
28) -62.149 1.243
29) 144.422 1.400 2.000690
30) 36.102 2.618
31) 59.497 5.244 1.552981
32) -38.000 1.250 1.953750
33) -67.619 0.600
34) 35.758 3.253 1.603420
35) 131.583 D35
36) 82.784 1.000 1.620410
37) 34.548 D37
38) 1543.160 2.834 1.737999
39) -52.203 2.166
40) -47.626 1.000 1.883000
41) 175.302 D41
42) -921.731 1.000 1.497820
43) 42.679 1.424
44) 46.578 5.331 1.737999
45) 385.606 31.575
46) ∞ 1.600 1.516800
47) ∞ 0.000

[Focal length data for each group]
Group Initial surface Focal length
G1 1 219.004
G2 5 435.981
G3 10 -37.321
G4 18 45.642
G5 36 -96.333
G6 38 -121.690
G7 42 501.930

[Variable interval data]
When focusing at infinity When focusing on a close-up object Telephoto end Wide-angle end Telephoto end Wide-angle end
D4 51.500 1.500 51.500 1.500
D9 25.600 1.300 25.600 1.300
D17 2.100 42.514 2.100 42.514
D35 3.400 2.624 33.408 3.482
D37 10.282 15.782 11.274 24.000
D41 47.700 26.860 16.700 17.783

Figure 6(a) is a diagram of various aberrations of the optical system of the third embodiment when focusing on an object at infinity in the wide-angle end state, Figure 6(b) is a diagram of various aberrations of the optical system of the third embodiment when focusing on a close object in the wide-angle end state, Figure 6(c) is a diagram of various aberrations of the optical system of the third embodiment when focusing on an object at infinity in the telephoto end state, and Figure 6(d) is a diagram of various aberrations of the optical system of the third embodiment when focusing on a close object in the telephoto end state.

From each aberration diagram, it can be seen that the optical system of this embodiment effectively suppresses aberration fluctuations during focusing and zooming, and has high optical performance.

(Fourth Example)

Figure 7 is a cross-sectional view of the optical system of the fourth embodiment when focused on an object at infinity in the telephoto end state.

The optical system of this embodiment has, 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 negative refractive power, and a fourth lens group G4 having positive refractive power.

The first lens group G1 is composed of, in order from the object side, a biconvex positive lens L1, a plano-convex lens L2 with a convex surface facing the object side, a cemented negative lens of a biconvex positive lens L3 and a biconcave negative lens L4, a biconvex positive lens L5, a cemented negative lens of a biconvex positive lens L6 and a biconcave negative lens L7, a negative meniscus lens L8 with a convex surface facing the object side, a biconcave negative lens L9, a biconcave positive lens L10, a positive meniscus lens L11 with a convex surface facing the object side, a biconcave negative lens L12, an aperture stop S, a positive meniscus lens L13 with a convex surface facing the image side, a negative meniscus lens L14 with a convex surface facing the object side, a cemented positive lens of a biconvex positive lens L15 and a negative meniscus lens L16 with a convex surface facing the image side, and a positive meniscus lens L17 with a convex surface facing the object side.

The second lens group G2 is made up of a cemented negative lens consisting of a biconvex positive lens L18 and a biconcave negative lens L19.

The third lens group G3 consists of, from the object side, a biconvex positive lens L20 and a biconcave negative lens L21.

The fourth lens group G4 consists of, from the object side, a biconcave negative lens L22 and a positive meniscus lens L23 with its convex surface facing the object side.

An image sensor (not shown) composed of a CCD or CMOS or the like is disposed on the image plane I.

A filter FL is placed between the optical system of this embodiment and the image plane I.

The optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3, which is disposed adjacent to the second lens group, along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 and the third lens group G3 are moved from the object side to the image side along different trajectories.

In the optical system of this embodiment, among the lenses in the first lens group G1, the cemented positive lens consisting of a biconvex positive lens L15 and a negative meniscus lens L16 with its convex surface facing the image side is configured as an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis.

The values of the optical system in this embodiment are listed in Table 4 below.

(Table 4)
[Overall specifications]
ft 362.51
Fnot 5.76
TLt 284.50
Image height 21.70
ωt 3.32°

[Lens specifications]
mrd nd
1) 464.984 3.830 1.487490
2) -464.984 0.150
3) 178.061 4.560 1.437001
4) ∞ 51.500
5) 63.221 7.030 1.497820
6) -658.500 1.000 1.804400
7) 57.457 1.530
8) 56.530 7.420 1.437001
9) -447.440 25.600
10) 44.719 5.632 1.740770
11) -136.661 1.500 1.755000
12) 36.855 4.557
13) ∞ 0.000 (imaginary plane)
14) 669.469 1.200 1.755000
15) 59.196 5.214
16) -46.293 1.200 1.755000
17) ∞ 8.094
18) 95.580 4.642 1.672700
19) -58.484 0.100
20) ∞ 0.000 (imaginary plane)
21) ∞ 0.000 (imaginary plane)
22) 35.401 4.036 1.497820
23) 253.508 3.108
24) -91.119 1.200 1.860740
25) 291.745 2.352
26> ∞ 11.710 (aperture stop)
27) -125.942 2.310 1.808090
28) -60.541 0.600
29) 134.570 1.400 2.000690
30) 34.633 2.730
31) 59.403 5.160 1.552981
32) -38.045 1.250 1.953750
33) -67.886 0.660
34) 35.224 3.500 1.603420
35) 140.226 D35
36) 120.647 2.260 1.850260
37) -120.465 1.000 1.729160
38) 35.481 D38
39) 560.475 2.630 1.654115
40) -50.042 2.310
41) -44.883 1.000 1.902650
42) 660.951 D42
43) -285.763 1.000 1.497820
44) 43.194 1.460
45) 47.384 5.670 1.738000
46) 1194.653 29.620
47) ∞ 1.600 1.516800
48) ∞ 0.000

[Focal length data for each group]
Group Initial surface Focal length
G1 1 133.939
G2 36 -81.740
G3 39 -153.334
G4 43 502.733

[Variable interval data]
When focusing on infinity When focusing on a close-up object
D35 3.467 28.145
D38 8.800 8.704
D42 48.913 24.331

Figure 8(a) is a diagram showing various aberrations of the optical system of the fourth embodiment when focusing on an object at infinity in the telephoto end state, and Figure 8(b) is a diagram showing various aberrations of the optical system of the fourth embodiment when focusing on an object at close range in the telephoto end state.

From each aberration diagram, it can be seen that the optical system of this embodiment effectively suppresses aberration fluctuations during focusing and has high optical performance.

According to each of the above embodiments, an optical system with good optical performance can be realized.

Below is a list of conditional expressions and the corresponding values for each example.

γi is the image plane transfer coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups, Σ|γi| is the sum of the absolute values of the image plane transfer coefficients of the multiple focusing groups, and Fnot is the F-number in the telephoto end state of the optical system. |γ|max is the maximum of the absolute values of the image plane transfer coefficients of the multiple focusing groups, and |γ|min is the minimum of the absolute values of the image plane transfer coefficients of the multiple focusing groups. ωt is the half angle of view in the telephoto end state of the optical system.

The image plane movement coefficient γi of the focusing group Fi among the multiple focusing groups is expressed by the following equation (a).
(a) γi = (1-βi ² ) × βiR ²
however,
βi: Lateral magnification of the focusing group Fi βiR: Total lateral magnification of the lens located on the image side of the focusing group Fi in the optical system

TLt is the total optical length of the optical system in the telephoto end state, and ft is the focal length of the entire optical system in the telephoto end state. Ymax is the maximum image height. fF1 is the focal length of the focusing group located closest to the object among the multiple focusing groups, and FD is the distance on the optical axis between the focusing group located closest to the object among the multiple focusing groups and the focusing group located closest to the image among the multiple focusing groups when focusing at infinity in the telephoto end state. fF2 is the focal length of the focusing group located second from the object side among the multiple focusing groups.

βF1 is the lateral magnification of the focusing group located closest to the object among the multiple focusing groups, and βF2 is the lateral magnification of the focusing group located second from the object among the multiple focusing groups. fvr is the focal length of the vibration isolation group. fw is the focal length of the entire optical system in the wide-angle end state. MV1 is the amount of movement in the optical axis direction when changing magnification, with the image plane side of the first moving group being positive, MV2 is the amount of movement in the optical axis direction when changing magnification, with the image plane side of the second moving group being positive, and MV3 is the amount of movement in the optical axis direction when changing magnification, with the image plane side of the third moving group being positive.

[Conditional expression list]
Example 1 2 3 4
(1) Σ|γi| * (5.76/Fnot) : 6.419 6.388 6.414 6.421
(2) |γ|max / |γ|min : 4.305 4.300 2.927 4.305
(3) ωt: 3.104 3.117 3.104 3.324
(4) TLt / ft: 0.733 0.729 0.733 0.785
(5) Σ|γi|*(5.76/Fnot)*(Ymax/21.63): 6.419 6.388 6.414 6.422
(6) (-fF1) / FD: 9.289 18.446 9.370 9.289
(7) fF1 / fF2: 0.533 0.578 0.792 0.533
(8) βF1 / βF2: 1.217 1.136 1.009 1.217
(9) fvr/ft: 0.202 0.202 0.202 0.217
(10) ft/fw: 3.765 3.767 3.767 -
(11) -(MV1+MV2+MV3)/TLt: 0.149 0.153 0.147 -

The above examples show specific examples of the present invention, and the present invention is not limited to these. The following contents can be adopted as appropriate within the scope that does not impair the optical performance of the optical system of the embodiment of the present application.

In addition, the lens surfaces of the lenses constituting the optical system of each of the above embodiments may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range. This reduces flare and ghosting, and achieves high-contrast optical performance.

Next, a camera equipped with the optical system of this embodiment will be described with reference to FIG.
FIG. 9 is a schematic diagram of a camera equipped with the optical system of this embodiment.

The camera 1 is a so-called mirrorless camera with interchangeable lenses that has the optical system according to the first embodiment described above as the photographic lens 2.

In camera 1, light from an object (subject) (not shown) is collected by photographing lens 2 and reaches image sensor 3. Image sensor 3 converts the light from the subject into image data. The image data is displayed on electronic viewfinder 4. This allows a photographer with his or her eye positioned at eyepoint EP to observe the subject.

When the photographer presses a release button (not shown), the image data is stored in a memory (not shown). In this way, the photographer can photograph the subject using camera 1.

The optical system of the first embodiment mounted on the camera 1 as the photographic lens 2 is an optical system with good optical performance. Therefore, the camera 1 can achieve good optical performance. Note that even if a camera is constructed with the optical system of the second to fourth embodiments mounted on the photographic lens 2, the same effect as the camera 1 can be achieved.

Finally, a method for manufacturing the optical system of this embodiment will be outlined with reference to FIG.
FIG. 10 is a flowchart showing an outline of the method for manufacturing the optical system of this embodiment.

The manufacturing method for the optical system of this embodiment shown in FIG. 10 includes the following steps S1 to S4.

Step S1: Prepare multiple focusing groups.

Step S2: When focusing, the multiple focusing groups are made to move along the optical axis on different trajectories.

Step S3: The following condition is satisfied when the optical system is focused on an object at infinity in the telephoto end state.
(1) 4.00 < Σ | γ i | × (5.76 / F not ) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the multiple focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of the multiple focusing groups. Fnot: F-number in the telephoto end state of the optical system.

The manufacturing method for the optical system of this embodiment makes it possible to manufacture an optical system with good imaging performance.

It will be appreciated by those skilled in the art that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the present invention.

S aperture stop I image plane 1 camera 2 photographing lens 3 imaging element

Claims (20)

The optical system is composed of, in order from the object side, a first lens group having positive refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, a sixth lens group having negative refractive power, and a seventh lens group having positive refractive power,
When changing magnification from the wide-angle end state to the telephoto end state, the spacing between adjacent lens groups changes,
During focusing, a plurality of focusing groups, each of which includes the fifth lens group and the sixth lens group as a focusing group , move along an optical axis along a different trajectory,
An optical system that satisfies the following condition when focusing on an object at infinity in the telephoto end state.
4.00 < Σ|γi| × (5.76/Fnot) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the plurality of focusing groups. Σ|γi|: Sum of the absolute values of the image plane movement coefficients of each of the plurality of focusing groups. Fnot: F-number in the telephoto end state of the optical system. 2. The optical system according to claim 1, wherein the following condition is satisfied when focusing on an object at infinity in the telephoto end state:
0.10 < |γ|max/|γ|min < 10.00
however,
|γ|max: the maximum absolute value of the image plane movement coefficients of the plurality of focusing groups. |γ|min: the minimum absolute value of the image plane movement coefficients of the plurality of focusing groups. 3. The optical system according to claim 1, wherein the following condition is satisfied:
2.20° < ωt < 13.00°
however,
ωt: Half angle of view in the telephoto end state of the optical system 4. The optical system according to claim 1, which satisfies the following condition:
0.40 < TLt / ft < 0.90
however,
TLt: total optical length of the optical system in the telephoto end state ft: focal length of the entire optical system in the telephoto end state 5. The optical system according to claim 1, which satisfies the following condition:
2.00 < (-fF1)/FD
however,
fF1: focal length of the focusing group arranged closest to the object among the plurality of focusing groups; FD: distance on the optical axis between the focusing group arranged closest to the object among the plurality of focusing groups and the focusing group arranged closest to the image among the plurality of focusing groups when focusing on infinity in the telephoto end state a vibration reduction group that performs image stabilization by moving in a direction perpendicular to an optical axis, the vibration reduction group being disposed closer to an object than the plurality of focusing groups;
6. The optical system according to claim 1, which satisfies the following condition:
0.10 < fvr/ft < 0.30
however,
fvr: focal length of the vibration reduction group ft: focal length of the entire optical system in the telephoto end state The optical system according to claim 6 , wherein the vibration reduction group is disposed on the object side adjacent to the focusing group disposed furthest to the object side among the plurality of focusing groups. 8. The optical system according to claim 1, which satisfies the following condition:
2.00 < ft/fw < 20.00
however,
ft: focal length of the entire optical system in the telephoto end state fw: focal length of the entire optical system in the wide-angle end state 9. The optical system according to claim 1, wherein the groups that move during zooming are, in order from the object side, a first moving group, a second moving group, and a third moving group, and the following condition is satisfied: 1< $1 mn>1<$1mn> 1 .
0.10 < - (MV1 + MV2 + MV3) / TLt < 0.30
however,
MV1: Amount of movement of the first moving group in the optical axis direction when the image surface side of the first moving group is changed, with the positive side being the image surface side of the first moving group. MV2: Amount of movement of the second moving group in the optical axis direction when the image surface side of the second moving group is changed, with the positive side being the image surface side of the second moving group. MV3: Amount of movement of the third moving group in the optical axis direction when the image surface side of the third moving group is changed, with the positive side being the image surface side of the third moving group. TLt: Total optical length of the optical system in the telephoto end state. 10. The optical system according to claim 1, wherein when focusing on an object at infinity, the plurality of focusing groups move monotonically towards the object side during magnification change from the wide-angle end state to the telephoto end state. the optical system comprises, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, and a fourth lens group having positive refractive power;
During focusing, a plurality of focusing groups, each of which includes the second lens group and the third lens group as a focusing group, move along an optical axis along a different trajectory,
An optical system that satisfies the following condition when focusing on an object at infinity.
4.00 < Σ|γi| × (5.76/Fnot) < 10.00
however,
γi: Image plane movement coefficient indicating the paraxial image plane movement amount per unit movement amount in each of the plurality of focusing groups
Σ|γi|: The sum of the absolute values of the image plane movement coefficients of each of the multiple focusing groups
Fnot: F-number of the optical system 12. The optical system according to claim 11, which satisfies the following condition when focusing on an object at infinity:
0.10 < |γ|max/|γ|min < 10.00
however,
|γ|max: the maximum absolute value of the image plane movement coefficients of the multiple focusing groups
|γ|min: the smallest absolute value of the image plane movement coefficients of the multiple focusing groups 13. The optical system according to claim 11, which satisfies the following condition:
2.00 < (-fF1)/FD
however,
fF1: focal length of the focusing group arranged closest to the object among the plurality of focusing groups
FD: the distance on the optical axis between the focusing group arranged closest to the object among the plurality of focusing groups and the focusing group arranged closest to the image among the plurality of focusing groups when focusing at infinity 14. The optical system according to claim 11, further comprising an image stabilization group which performs image stabilization by moving in a direction perpendicular to the optical axis, and is disposed closer to the object side than the plurality of focusing groups. The optical system according to any one of claims 11 to 14, wherein a lens group arranged on the object side adjacent to the focusing group arranged closest to the object side among the plurality of focusing groups includes an image stabilization group that performs image stabilization by moving in a direction perpendicular to the optical axis. The optical system according to any one of claims 1 to 15, wherein at least two of the plurality of focusing groups each have at least one positive lens and at least one negative lens. The optical system according to any one of claims 1 to 16, which satisfies the following condition:
4.00 < Σ|γi| × (5.76/Fnot) × (Ymax/21.63) < 10.00
however,
Ymax: Maximum image height The optical system according to any one of claims 1 to 17, which satisfies the following formula:
0.30 < fF1/fF2 < 1.00
however,
fF1: focal length of the focusing group arranged closest to the object among the plurality of focusing groups
fF2: focal length of the second focusing group from the object side among the plurality of focusing groups 19. The optical system according to claim 1, wherein the following condition is satisfied:
0.85 < βF1/βF2 < 1.40
however,
βF1: The lateral magnification of the focusing group arranged closest to the object among the plurality of focusing groups
βF2: The lateral magnification of the second focusing group from the object side among the plurality of focusing groups An optical instrument comprising the optical system according to any one of claims 1 to 19 .

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