JP6597086B2 - Zoom lens system - Google Patents

Description

  The present invention relates to a zoom lens system, for example, a telephoto zoom lens system suitable for use in an imaging device such as a digital camera.

  An optical system used in an imaging device such as a digital camera is required to be cheaper and have higher performance. As a telephoto zoom lens system, a lens system composed of a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a subsequent lens group having a positive refractive power as a whole is often used. .

  For example, Patent Documents 1-3 include a three-group zoom lens system including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. It is disclosed. The positive / negative positive three-group zoom lens system is suitable for an inexpensive optical system with a simple configuration.

JP-A-61-83514 JP 2008-122775 A JP 2013-11461 A

  However, the zoom lens system of Patent Document 1 has a large spherical aberration and coma aberration, and thus cannot provide sufficient optical performance. Further, the zoom lens system of Patent Document 2 does not have sufficient optical performance because correction of coma is insufficient. Furthermore, the zoom lens system of Patent Document 3 has a large chromatic aberration, so that sufficient optical performance cannot be obtained.

  The present invention has been made based on the above awareness of problems, and an object of the present invention is to obtain a zoom lens system that can correct various aberrations and obtain excellent optical performance.

In one aspect, the zoom lens system of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is decreased upon zooming from the short focal length end to the long focal length end. , At least the first lens group and the third lens group move; the first lens group includes, in order from the object side, a positive lens, a negative lens, and a positive lens; and the third lens group includes an object side. In order from the 3a lens group having a positive refractive power and the 3b lens group having a negative refractive power; the 3a lens group includes one or two positive lenses, a positive lens, and a negative lens. A cemented lens; and satisfying the following conditional expressions (1) and (2) : It is a sign.
(1) -5.5 <f1 / f2 <-4.5
(2) -0.4 <f3a / f3b <-0.01
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group ,
f3a: focal length of the 3a lens group,
f3b: focal length of the 3b lens group,
It is.
In the zoom lens system of the present invention, it is preferable that the 3a lens group includes two positive single lenses and satisfies the following conditional expression (4).
(4) Nd3p1> Nd3p2
However,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among the two positive single lenses in the 3a lens group,
Nd3p2: refractive index with respect to d-line of a positive single lens located on the image side among the two positive single lenses in the 3a lens group,
It is.
In another aspect, the zoom lens system of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is decreased upon zooming from the short focal length end to the long focal length end. , At least the first lens group and the third lens group move; the first lens group includes, in order from the object side, a positive lens, a negative lens, and a positive lens; and the third lens group includes an object side. In order from the 3a lens group having a positive refractive power and the 3b lens group having a negative refractive power; the 3a lens group includes one or two positive lenses, a positive lens, and a negative lens. The third lens group includes two positive single lenses; and The zoom lens system characterized by; expression (1), to satisfy the (4).
(1) -5.5 <f1 / f2 <-4.5
(4) Nd3p1> Nd3p2
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among the two positive single lenses in the 3a lens group,
Nd3p2: refractive index with respect to d-line of a positive single lens located on the image side among the two positive single lenses in the 3a lens group,
It is.

The zoom lens system of the present invention preferably satisfies the following conditional expression (2 ′) within the conditional expression range defined by conditional expression (2).
(2 ′) − 0.3 <f3a / f3b <−0.01

In the zoom lens system according to the present invention, it is preferable that the third lens group includes a positive single lens and satisfies the following conditional expression (3).
(3) Nd3p1> Nd3pb
However,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among positive single lenses in the third-a lens group,
Nd3pb: refractive index of the cemented lens in the 3a lens group with respect to the d-line of the positive lens,
It is.

The zoom lens system according to the present invention preferably satisfies the following conditional expression (5).
(5) νd3p> 80
However,
νd3p: Abbe number of at least one positive lens in the 3a lens group with respect to the d-line,
It is.

  It is preferable that the 3a lens group and the 3b lens group are separated at a place where the air space is maximum.

The zoom lens system according to the present invention preferably satisfies the following conditional expression (6).
(6) 2.6 <f1 / f3 <3.3
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
It is.

  According to the present invention, it is possible to obtain a zoom lens system capable of correcting various aberrations and obtaining excellent optical performance.

It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 1 of the zoom lens system according to the present invention. FIG. 2 is a diagram illustrating various aberrations in the configuration of FIG. 1. FIG. 2 is a lateral aberration diagram in the configuration of FIG. 1. 6 is a lens configuration diagram at the time of infinity focusing at the long focal length end of the numerical example 1. FIG. FIG. 5 is a diagram illustrating various aberrations in the configuration of FIG. 4. FIG. 5 is a lateral aberration diagram in the configuration of FIG. 4. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 2 of the zoom lens system by the present invention. FIG. 8 is a diagram illustrating various aberrations in the configuration of FIG. 7. FIG. 8 is a lateral aberration diagram in the configuration of FIG. 7. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 2; FIG. 11 is a diagram illustrating various aberrations in the configuration of FIG. 10. FIG. 11 is a lateral aberration diagram in the configuration of FIG. 10. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 3 of the zoom lens system by the present invention. FIG. 14 is a diagram illustrating various aberrations in the configuration of FIG. 13. FIG. 14 is a lateral aberration diagram in the configuration of FIG. 13. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 3; FIG. 17 is a diagram of various aberrations in the configuration of FIG. 16. FIG. 17 is a lateral aberration diagram in the configuration of FIG. 16. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 4 of the zoom lens system by the present invention. FIG. 20 is a diagram illustrating various aberrations in the configuration in FIG. 19. FIG. 20 is a lateral aberration diagram in the configuration of FIG. 19. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the numerical example 4; FIG. 23 is a diagram of various aberrations in the configuration of FIG. 22. FIG. 23 is a lateral aberration diagram in the configuration of FIG. 22. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 5 of the zoom lens system by the present invention. FIG. 26 is a diagram illustrating various aberrations in the configuration in FIG. 25. FIG. 26 is a lateral aberration diagram in the configuration of FIG. 25. It is a lens block diagram at the time of infinity focusing in the long focal distance end of the same numerical example 5. FIG. 29 is a diagram of various aberrations in the configuration of FIG. 28. FIG. 29 is a lateral aberration diagram in the configuration of FIG. 28. It is a simple movement figure which shows the zoom locus | trajectory of the zoom lens system by this invention.

  The zoom lens system of the present embodiment includes a first lens group G1 having a positive refractive power and a negative refractive power in order from the object side as shown in the simplified movement diagram of FIG. The second lens group G2 and the third lens group G3 having a positive refractive power. The third lens group G3 includes, in order from the object side, a third a lens group G3a having a positive refractive power and a third b lens group G3b having a negative refractive power. The 3a lens group G3a and the 3b lens group G3b are separated at a place where the air space is maximum. A diaphragm S that moves integrally with the third lens group G3 is located between the second lens group G2 and the third lens group G3 (immediately before the third lens group G3). I is the image plane.

  In the zoom lens system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 increases upon zooming from the short focal length end (Wide) to the long focal length end (Tele), and the second lens The first to third lens groups G1 to G3 move in the optical axis direction so that the distance between the group G2 and the third lens group G3 decreases. More specifically, at the time of zooming from the short focal length end to the long focal length end, the first lens group G1 and the third lens group G3 monotonously move (drawn) toward the object side, and the second lens group G2 After moving to the image side, it returns to the object side (U-turn). Here, at the time of zooming from the short focal length end to the long focal length end, it is sufficient that at least the first lens group G1 and the third lens group G3 move in the optical axis direction, and the behavior of the second lens group is flexible. (For example, a mode of monotonously moving to the object side or the image side, or a mode of being fixed with respect to the image plane I without moving in the optical axis direction is possible).

  The first lens group G1 is composed of a positive lens 11, a negative lens 12, and a cemented lens of a positive lens 13 in order from the object side through the numerical examples 1-5. Note that the positive / negative order of the cemented lens may be reversed.

In Numerical Example 1, the second lens group G2 includes a cemented lens of a positive lens 21 and a negative lens 22, and a negative lens 23 in order from the object side. Note that the positive / negative order of the cemented lens may be reversed.
In Numerical Example 2-5, the second lens group G2 includes, in order from the object side, a cemented lens of a negative lens 21 ′ and a positive lens 22 ′ and a negative lens 23 ′. Note that the positive / negative order of the cemented lens may be reversed.

In the numerical value example 1, the third-a lens group G3a includes a positive lens 31, a cemented lens of a positive lens 32 and a negative lens 33, and a positive lens 34 in order from the object side. Note that the positive / negative order of the cemented lens may be reversed.
In Numerical Example 2-4, the third-a lens group G3a is composed of a positive lens 31 ′, a positive lens 32 ′, and a cemented lens of a positive lens 33 ′ and a negative lens 34 ′ in order from the object side. Note that the positive / negative order of the cemented lens may be reversed.
In Numerical Example 5, the third-a lens group G3a includes, in order from the object side, a positive lens 31 ″ and a cemented lens of a positive lens 32 ″ and a negative lens 33 ″. May be reversed.

In Numerical Examples 1, 2, 4, and 5, the third lens group G3b includes a negative lens 35 and a positive lens 36 in order from the object side.
In Numerical Example 3, the third lens group G3b includes, in order from the object side, a cemented lens of a positive lens 35 ′ and a negative lens 36 ′ that are positioned, and a positive lens 37 ′. Note that the positive / negative order of the cemented lens may be reversed.

  In the zoom lens system of the present embodiment, the first lens group G1 has a three-lens configuration including a positive lens 11, a negative lens 12, and a positive lens 13. By taking the so-called triplet arrangement of positive and negative, it is possible to effectively correct spherical aberration, coma aberration, curvature of field, and the like. Further, the negative lens 12 in the middle and the positive lens 13 on the image side are formed as a cemented lens in which the strong curvature side of the negative lens 12 is cemented with the positive lens 13, thereby reducing performance degradation due to manufacturing errors (so-called low sensitivity). Can be achieved.

  The zoom lens system of the present embodiment is a so-called telephoto camera in which a third lens group G3a having a positive refractive power and a third lens group G3b having a negative refractive power are arranged with a maximum air gap between them. It has a type lens configuration. This is effective in reducing the size of the lens system, effectively correcting spherical aberration and coma with the 3a lens group G3a, and effectively correcting curvature of field and distortion with the 3b lens group G3b. be able to. The third-a lens group G3a is composed of two or three positive lenses and one negative lens, and thereby, particularly, spherical aberration, coma aberration, and chromatic aberration can be corrected effectively.

Conditional expression (1) defines the ratio between the focal length of the first lens group G1 and the focal length of the second lens group G2. Satisfying the conditional expression (1) makes it possible to satisfactorily correct field curvature and distortion at the short focal length end and coma aberration at the long focal length end to obtain excellent optical performance.
If the upper limit of conditional expression (1) is exceeded, the power of the first lens group G1 becomes too strong, and particularly coma aberration occurs at the long focal length end.
When the lower limit of conditional expression (1) is exceeded, the power of the second lens group G2 becomes too strong, and particularly, field curvature and distortion are greatly generated at the short focal length end.

Conditional expressions (2) and (2 ′) define the ratio of the focal length of the 3a lens group G3a to the focal length of the 3b lens group G3b. By satisfying conditional expression (2), it is possible to satisfactorily correct spherical aberration, coma aberration, and distortion aberration and obtain excellent optical performance. This effect can be obtained more significantly by satisfying conditional expression (2 ′).
When the upper limit of conditional expressions (2) and (2 ′) is exceeded, the power of the third-a lens group G3a becomes too strong, and the correction of spherical aberration and coma becomes insufficient.
If the lower limit of conditional expression (2) is exceeded, the power of the third lens group G3b will be too strong, and the correction of distortion will be insufficient.

  In the zoom lens system of the present embodiment, the 3a lens group G3a includes one or two positive single lenses and a cemented lens of a positive lens and a negative lens, and is the most object in the 3a lens group G3a. A positive lens is located on the side.

  Conditional expression (3) indicates that the refractive index with respect to the d-line of the positive single lens located on the object side among the positive single lenses in the third-a lens group G3a is d-line of the positive lens of the cemented lens in the third-a lens group G3a. It is specified that the refractive index is larger than the refractive index.

  Conditional expression (4) indicates that the refractive index with respect to the d-line of the positive single lens located on the object side among the two positive single lenses in the 3a lens group G3a is two positive singles in the 3a lens group G3a. It defines that the positive refractive index lens located on the image side of the lens is larger than the refractive index with respect to the d-line.

Since the third lens group G3 converges the light beam diverged by the second lens group G2 having a negative refractive power, spherical aberration is likely to occur particularly in the positive lens closest to the object side.
The zoom lens system of the present embodiment sets the highest refractive index for the d-line of the positive lens located closest to the object side in the 3a lens group G3a (for example, satisfies the conditional expressions (3) and (4)). Thus, it is possible to correct spherical aberration well and obtain excellent optical performance.
On the other hand, when the refractive index with respect to the d-line of the positive lens located closest to the object side in the 3a lens group G3a is low (for example, when the conditional expressions (3) and (4) are not satisfied), the 3a lens group G3a A large spherical aberration occurs in the positive lens located closest to the object.

  Conditional expression (5) stipulates that at least one positive lens in the third-a lens group G3a is made of a low-dispersion glass material having an Abbe number exceeding 80 for the d-line. Satisfying conditional expression (5) makes it possible to correct axial chromatic aberration satisfactorily. In this embodiment, the positive lens that satisfies the conditional expression (5) is a positive lens that constitutes the cemented lens in the third-a lens group G3a. Thereby, generation | occurrence | production of spherical aberration and a coma aberration can be suppressed.

Conditional expression (6) defines the ratio between the focal length of the first lens group G1 and the focal length of the third lens group G3. By satisfying conditional expression (6), it is possible to satisfactorily correct spherical aberration, chromatic aberration, and field curvature, particularly at the long focal length end, and obtain excellent optical performance.
If the upper limit of conditional expression (6) is exceeded, the power of the third lens group G3 will be too strong, and spherical aberration and chromatic aberration will occur greatly, especially at the long focal length end.
If the lower limit of conditional expression (6) is exceeded, the power of the first lens group G1 becomes too strong, and a large curvature of field occurs particularly at the long focal length end.

Next, specific numerical value examples 1-5 will be described. In the various aberration diagrams and lateral aberration diagrams and tables, d-line, g-line and C-line are aberrations for each wavelength, S is sagittal, M is meridional, FNO. Is F-number, f is the focal length of the whole system, W Is half angle of view (°), Y is image height, fB Is the back focus, L is the total lens length, R is the radius of curvature, d is the lens thickness or lens spacing, N (d) is the refractive index for the d-line, and ν (d) is the Abbe number for the d-line. The f-number, focal length, half angle of view, image height, back focus, total lens length, and lens interval d that changes with zooming are shown in the order of short focal length end-intermediate focal length-long focal length end. Yes. The unit of length is [mm]. Throughout the numerical examples 1-5, no aspheric lens is used.

[Numerical Example 1]
1 to 6 and Tables 1 to 3 show Numerical Example 1 of the zoom lens system according to the present invention. FIG. 1 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 2 is a diagram of various aberrations, FIG. 3 is a diagram of its lateral aberration, and FIG. FIG. 5 is a diagram showing various aberrations, and FIG. 6 is a diagram showing lateral aberrations. Table 1 shows surface data, Table 2 shows various data, and Table 3 shows lens group data.

  The zoom lens system according to Numerical Example 1 includes, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. It consists of. The third lens group G3 includes, in order from the object side, a third a lens group G3a having a positive refractive power and a third b lens group G3b having a negative refractive power. The 3a lens group G3a and the 3b lens group G3b are separated at a place where the air space is the maximum. A diaphragm S that moves integrally with the third lens group G3 is located between the second lens group G2 and the third lens group G3 (immediately before the third lens group G3).

  The first lens group G1 includes, in order from the object side, a positive meniscus lens 11 convex toward the object side, a negative meniscus lens 12 convex toward the object side, and a biconvex positive lens 13. The negative meniscus lens 12 and the biconvex positive lens 13 are cemented.

  The second lens group G2 includes, in order from the object side, a positive meniscus lens 21, a biconcave negative lens 22, and a biconcave negative lens 23 that are convex on the image side. The positive meniscus lens 21 and the biconcave negative lens 22 are cemented.

  The third-a lens group G3a includes, in order from the object side, a biconvex positive lens 31, a biconvex positive lens 32, a negative meniscus lens 33 convex on the image side, and a positive meniscus lens 34 convex on the object side. The biconvex positive lens 32 and the negative meniscus lens 33 are cemented.

  The third lens group G3b is composed of a biconcave negative lens 35 and a biconvex positive lens 36 in this order from the object side.

(Table 1)
Surface data surface number R d N (d) ν (d)
1 79.025 4.16 1.48749 70.4
2 193.715 0.10
3 92.843 1.40 1.70154 41.2
4 44.333 7.70 1.49700 81.6
5 -362.429 d5
6 -150.957 2.96 1.84666 23.8
7 -30.746 1.20 1.65 160 58.4
8 55.215 2.59
9 -32.061 1.20 1.77250 49.6
10 60205.156 d10
11 stop ∞ 0.30
12 799.074 2.69 1.69680 55.5
13 -42.077 0.10
14 73.902 3.60 1.49700 81.6
15 -34.085 1.20 1.90366 31.3
16 -253.531 0.10
17 32.611 2.68 1.60311 60.7
18 2672.399 15.67
19 -188.159 1.20 1.88300 40.8
20 31.177 6.24
21 1034.673 2.74 1.80610 33.3
22 -44.934-
(Table 2)
Various data zoom ratio (zoom ratio) 4.30
Short focal length end Intermediate focal length Long focal length end
FNO. 4.6 4.8 5.9
f 56.06 100.00 241.00
W 14.5 7.9 3.3
Y 14.24 14.24 14.24
fB 56.34 59.34 79.87
L 153.77 180.14 200.00
d5 8.69 40.53 60.31
d10 30.91 22.44 2.00
(Table 3)
Lens group data group Start surface Focal length
1 1 126.32
2 6 -27.69
3 12 39.73

[Numerical Example 2]
7 to 12 and Tables 4 to 6 show Numerical Example 2 of the zoom lens system according to the present invention. FIG. 7 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 8 is a diagram of various aberrations thereof, FIG. 9 is a lateral aberration diagram thereof, and FIG. 10 is a graph at the time of focusing at infinity at the long focal length end. FIG. 11 is a diagram showing various aberrations, and FIG. 12 is a diagram showing lateral aberrations. Table 4 shows surface data, Table 5 shows various data, and Table 6 shows lens group data.

The lens configuration of Numerical Example 2 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) In the first lens group G1, the positive lens 11 is a biconvex positive lens, and the positive lens 13 is a positive meniscus lens convex toward the object side.
(2) The second lens group G2 includes, in order from the object side, a biconcave negative lens 21 ′, a positive meniscus lens 22 ′ convex toward the object side, and a biconcave negative lens 23 ′. The biconcave negative lens 21 ′ and the positive meniscus lens 22 ′ are cemented.
(3) The third-a lens group G3a includes, in order from the object side, a biconvex positive lens 31 ′, a positive meniscus lens 32 ′ convex to the object side, a biconvex positive lens 33 ′, and a negative meniscus convex to the image side. Lens 34 '. The biconvex positive lens 33 ′ and the negative meniscus lens 34 ′ are cemented.

(Table 4)
Surface data surface number R d N (d) ν (d)
1 79.022 5.20 1.51633 64.1
2 -1041.901 0.15
3 75.658 2.00 1.80 100 35.0
4 42.544 6.40 1.49700 81.6
5 249.394 d5
6 -136.260 1.40 1.71299 53.9
7 17.802 3.20 1.84666 23.8
8 41.388 2.32
9 -34.559 1.10 1.80 400 46.6
10 1345.395 d10
11 stops ∞ 1.00
12 113.633 2.90 1.60311 60.7
13 -58.266 0.15
14 50.193 2.62 1.58913 61.2
15 1673.903 6.95
16 57.449 3.60 1.49700 81.6
17 -36.444 1.30 1.84666 23.8
18 -165.890 15.76
19 -352.132 1.50 1.83400 37.2
20 34.307 6.63
21 93.637 3.90 1.68893 31.1
22 -48.282-
(Table 5)
Various data zoom ratio (magnification ratio) 4.75
Short focal length end Intermediate focal length Long focal length end
FNO. 4.5 4.9 5.9
f 50.72 100.01 241.00
W 16.1 7.9 3.3
Y 14.24 14.24 14.24
fB 43.70 52.13 74.82
L 160.02 181.71 200.51
d5 16.77 41.27 56.41
d10 31.47 20.23 1.20
(Table 6)
Lens group data group Start surface Focal length
1 1 114.95
2 6 -23.23
3 12 40.31

[Numerical Example 3]
13 to 18 and Tables 7 to 9 show Numerical Example 3 of the zoom lens system according to the present invention. FIG. 13 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 14 is a diagram showing various aberrations thereof, FIG. 15 is a lateral aberration diagram thereof, and FIG. FIG. 17 is a diagram showing various aberrations, and FIG. 18 is a diagram showing its lateral aberration. Table 7 shows surface data, Table 8 shows various data, and Table 9 shows lens group data.

The lens configuration of Numerical Example 3 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The positive lens 13 of the first lens group G1 includes a positive meniscus lens convex toward the object side.
(2) The second lens group G2 includes, in order from the object side, a biconcave negative lens 21 ′, a positive meniscus lens 22 ′ convex toward the object side, and a negative meniscus lens 23 ′ convex toward the image side. The biconcave negative lens 21 ′ and the positive meniscus lens 22 ′ are cemented.
(3) The 3a lens group G3a includes, in order from the object side, a positive meniscus lens 31 ′ convex to the image side, a biconvex positive lens 32 ′, a biconvex positive lens 33 ′, and a negative meniscus convex to the image side. Lens 34 '. The biconvex positive lens 33 ′ and the negative meniscus lens 34 ′ are cemented.
(4) The third lens group G3b is composed of, in order from the object side, a biconvex positive lens 35 ′, a biconcave negative lens 36 ′, and a positive meniscus lens 37 ′ convex toward the object side. The biconvex positive lens 35 ′ and the biconcave negative lens 36 ′ are cemented.

(Table 7)
Surface data surface number R d N (d) ν (d)
1 85.191 4.75 1.61800 63.4
2 468.494 0.15
3 76.133 2.00 1.90366 31.3
4 48.477 8.00 1.49700 81.6
5 882.414 d5
6 -244.975 1.20 1.69680 55.5
7 20.243 4.30 1.84666 23.8
8 36.679 11.21
9 -37.896 1.10 1.80420 46.5
10 -363.295 d10
11 stops ∞ 1.00
12 -370.768 3.10 1.61800 63.4
13 -63.154 0.15
14 133.748 3.00 1.48749 70.4
15 -177.052 0.30
16 28.562 5.10 1.49700 81.6
17 -77.981 1.00 1.84666 23.8
18 -1710.856 26.70
19 38.003 3.00 1.62004 36.3
20 -23.536 1.20 1.83481 42.7
21 22.988 7.70
22 31.950 2.80 1.58144 40.9
23 2948.802-
(Table 8)
Various data zoom ratio (magnification ratio) 5.09
Short focal length end Intermediate focal length Long focal length end
FNO. 4.2 4.2 5.9
f 57.00 150.00 290.01
W 14.5 5.3 2.8
Y 14.24 14.24 14.24
fB 45.96 47.66 85.69
L 168.17 194.31 220.66
d5 2.98 42.51 46.01
d10 31.47 16.38 1.20
(Table 9)
Lens group data group Start surface Focal length
1 1 110.99
2 6 -24.39
3 12 40.36

[Numerical Example 4]
19 to 24 and Tables 10 to 12 show Numerical Example 4 of the zoom lens system according to the present invention. 19 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 20 is a diagram showing various aberrations, FIG. 21 is a lateral aberration diagram, and FIG. 22 is a diagram at the time of focusing at infinity at the long focal length end. FIG. 23 is a diagram showing various lens aberrations, and FIG. 24 is a diagram showing lateral aberrations. Table 10 shows surface data, Table 11 shows various data, and Table 12 shows lens group data.

The lens configuration of Numerical Example 4 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The positive lens 13 of the first lens group G1 includes a positive meniscus lens convex toward the object side.
(2) The second lens group G2 includes, in order from the object side, a biconcave negative lens 21 ′, a positive meniscus lens 22 ′ convex toward the object side, and a biconcave negative lens 23 ′. The biconcave negative lens 21 ′ and the positive meniscus lens 22 ′ are cemented.
(3) The third-a lens group G3a includes, in order from the object side, a biconvex positive lens 31 ′, a biconvex positive lens 32 ′, a biconvex positive lens 33 ′, and a biconcave negative lens 34 ′. The biconvex positive lens 33 ′ and the biconcave negative lens 34 ′ are cemented.

(Table 10)
Surface data surface number R d N (d) ν (d)
1 77.049 5.00 1.48749 70.2
2 880.280 0.15
3 91.792 2.00 1.72047 34.7
4 47.991 6.60 1.49700 81.6
5 763.605 d5
6 -91.008 1.30 1.69680 55.5
7 19.973 3.10 1.84666 23.8
8 51.160 2.16
9 -46.625 1.10 1.80 400 46.6
10 183.868 d10
11 stops ∞ 1.00
12 174.453 2.80 1.60311 60.7
13 -59.289 0.15
14 52.505 2.52 1.51633 64.1
15 -167.083 4.81
16 39.260 3.70 1.49700 81.6
17 -59.646 1.30 1.84666 23.8
18 378.236 14.37
19 -171.718 1.50 1.83400 37.2
20 35.826 6.88
21 121.984 3.70 1.68893 31.1
22 -47.807-
(Table 11)
Various data zoom ratio (magnification ratio) 4.24
Short focal length end Intermediate focal length Long focal length end
FNO. 4.5 4.7 5.9
f 56.90 100.00 241.00
W 14.5 8.0 3.3
Y 14.24 14.24 14.24
fB 48.15 52.76 77.09
L 163.26 181.62 200.09
d5 19.50 42.64 57.65
d10 31.47 22.07 1.20
(Table 12)
Lens group data group Start surface Focal length
1 1 119.34
2 6 -25.39
3 12 40.53

[Numerical Example 5]
25 to 30 and Tables 13 to 15 show Numerical Example 5 of the zoom lens system according to the present invention. FIG. 25 is a lens configuration diagram at the time of focusing at infinity at the short focal length end, FIG. 26 is a diagram of various aberrations thereof, FIG. 27 is a diagram of its lateral aberration, and FIG. FIG. 29 is a diagram showing various aberrations, and FIG. 30 is a diagram showing its lateral aberration. Table 13 shows surface data, Table 14 shows various data, and Table 15 shows lens group data.

The lens configuration of Numerical Example 5 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The second lens group G2 includes, in order from the object side, a biconcave negative lens 21 ′, a positive meniscus lens 22 ′ convex toward the object side, and a negative meniscus lens 23 ′ convex toward the image side. The biconcave negative lens 21 ′ and the positive meniscus lens 22 ′ are cemented.
(2) The third-a lens group G3a is composed of, in order from the object side, a biconvex positive lens 31 ″, a biconvex positive lens 32 ″, and a negative meniscus lens 33 ″ convex to the image side. Biconvex positive lens 32 "And the negative meniscus lens 33" are cemented.

(Table 13)
Surface data surface number R d N (d) ν (d)
1 101.147 3.72 1.48749 70.2
2 373.480 0.15
3 80.388 2.00 1.72047 34.7
4 43.691 7.08 1.49700 81.6
5 -315.517 d5
6 -77.362 1.30 1.69680 55.5
7 17.344 3.10 1.84666 23.8
8 38.842 3.17
9 -40.449 1.10 1.80 400 46.6
10 -452.200 d10
11 stops ∞ 1.00
12 81.539 2.81 1.61800 63.4
13 -43.026 0.20
14 31.138 4.72 1.49700 81.6
15 -38.985 2.00 1.90366 31.3
16 -306.901 23.05
17 -148.634 1.50 1.83481 42.7
18 26.060 3.72
19 38.772 3.39 1.57501 41.5
20 -40.610-
(Table 14)
Various data zoom ratio (magnification ratio) 4.41
Short focal length end Intermediate focal length Long focal length end
FNO. 4.5 4.7 6.1
f 56.90 100.00 250.69
W 14.3 7.9 3.2
Y 14.24 14.24 14.24
fB 50.27 54.33 78.41
L 155.29 177.03 199.74
d5 12.89 38.12 55.37
d10 28.12 20.57 1.96
(Table 15)
Lens group data group Start surface Focal length
1 1 112.61
2 6 -23.96
3 12 38.25

Table 16 shows values for the conditional expressions of the numerical examples.
(Table 16)
Example 1 Example 2 Example 3
Conditional expression (1) -4.56 -4.95 -4.55
Conditional expression (2) -0.29 -0.02 -0.23
Conditional expression (3)
Nd3p1 1.69680 1.60311 1.61800
Nd3pb 1.49700 1.49700 1.49700
Conditional expression (4)
Nd3p1 1.69680 1.60311 1.61800
Nd3p2 1.49700 1.58913 1.48749
Conditional expression (5) 81.61 81.61 81.61
Conditional expression (6) 3.18 2.85 2.75
Example 4 Example 5
Conditional expression (1) -4.70 -4.70
Conditional expression (2) -0.11 -0.13
Conditional expression (3)
Nd3p1 1.60311 1.61800
Nd3pb 1.49700 1.49700
Conditional expression (4)
Nd3p1 1.60311 1.61800
Nd3p2 1.51633 1.49700
Conditional expression (5) 81.61 81.61
Conditional expression (6) 2.94 2.94

  As is clear from Table 16, Numerical Example 1 to Numerical Example 5 satisfy the conditional expressions (1) to (6), and as is apparent from the various aberration diagrams and lateral aberration diagrams, Aberrations and lateral aberrations are corrected relatively well.

  Even if a lens or a lens group having no substantial power is added to the zoom lens system included in the scope of claims of the present invention, it is included in the technical scope of the present invention. It ’s not avoided.)

In another aspect, the zoom lens system of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The distance between the first lens group and the second lens group is increased and the distance between the second lens group and the third lens group is decreased upon zooming from the short focal length end to the long focal length end. , At least the first lens group and the third lens group move; the third lens group includes, in order from the object side, a 3a lens group having a positive refractive power and a 3b lens group having a negative refractive power. The third-a lens group includes one or two positive lenses and a cemented lens of a positive lens and a negative lens; and satisfies the following conditional expressions (1) and (6): It is said.
(1) -5.5 <f1 / f2 <-4.5
(6) 2.6 <f1 / f3 <3.3
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
It is.

In still another aspect, the zoom lens system according to the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases during zooming from the short focal length end to the long focal length end. In addition, at least the first lens group and the third lens group move; the first lens group includes, in order from the object side, a positive lens, a negative lens, and a positive lens; and the following conditional expression (1 ) And (6) are satisfied.
(1) -5.5 <f1 / f2 <-4.5
(6) 2.6 <f1 / f3 <3.3
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
It is.

  It is preferable that the zoom lens system of these other embodiments satisfies the conditional expressions (2) to (5) of the present invention described above.

G1 First lens group 11 having a positive refractive power 11 Positive lens 12 Negative lens 13 Positive lens G2 Second lens group 21 having a negative refractive power 21 Positive lens 22 Negative lens 23 Negative lens 21 ′ Negative lens 22 ′ Positive lens 23 ′ Negative lens G3 Third lens group G3a with positive refractive power 3a lens group 31 with positive refractive power 31 Positive lens 32 Positive lens 33 Negative lens 34 Positive lens 31 'Positive lens 32' Positive lens 33 'Positive lens 34' Negative lens 31 " Positive lens 32 "Positive lens 33" Negative lens G3b 3b lens group 35 with negative refractive power Negative lens 36 Positive lens 35 'Positive lens 36' Negative lens 37 'Positive lens S Aperture I Image surface

Claims (6)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side;
At the time of zooming from the short focal length end to the long focal length end, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is decreased. The lens group and the third lens group move;
The first lens group includes, in order from the object side, a positive lens, a negative lens, and a positive lens;
The third lens group includes, in order from the object side, a 3a lens group having a positive refractive power and a 3b lens group having a negative refractive power;
The third-a lens group includes one or two positive lenses and a cemented lens of a positive lens and a negative lens; and satisfies the following conditional expressions (1) and (2) :
Zoom lens system characterized by
(1) -5.5 <f1 / f2 <-4.5
(2) -0.4 <f3a / f3b <-0.01
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group ,
f3a: focal length of the 3a lens group,
f3b: focal length of the 3b lens group. The zoom lens system according to claim 1 .
The 3a lens group includes two positive single lenses, and satisfies the following conditional expression (4).
(4) Nd3p1> Nd3p2
However,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among the two positive single lenses in the 3a lens group,
Nd3p2: The refractive index with respect to the d-line of the positive single lens located on the image side among the two positive single lenses in the third-a lens group. A first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power in order from the object side;
At the time of zooming from the short focal length end to the long focal length end, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is decreased. The lens group and the third lens group move;
The first lens group includes, in order from the object side, a positive lens, a negative lens, and a positive lens;
The third lens group includes, in order from the object side, a 3a lens group having a positive refractive power and a 3b lens group having a negative refractive power;
The third-a lens group includes one or two positive lenses and a cemented lens of a positive lens and a negative lens ;
The third-a lens group includes two positive single lenses; and satisfies the following conditional expressions (1) and (4) :
Zoom lens system characterized by
(1) -5.5 <f1 / f2 <-4.5
(4) Nd3p1> Nd3p2
However,
f1: the focal length of the first lens group,
f2: focal length of the second lens group ,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among the two positive single lenses in the 3a lens group,
Nd3p2: The refractive index with respect to the d-line of the positive single lens located on the image side among the two positive single lenses in the third-a lens group. The zoom lens system according to any one of claims 1 to 3 ,
The third lens group includes a positive single lens, and satisfies the following conditional expression (3).
(3) Nd3p1> Nd3pb
However,
Nd3p1: Refractive index with respect to d-line of a positive single lens located on the object side among positive single lenses in the third-a lens group,
Nd3pb: the refractive index of the cemented lens in the 3a lens group with respect to the d-line of the positive lens. The zoom lens system according to any one of claims 1 to 4,
A zoom lens system that satisfies the following conditional expression (5):
(5) νd3p> 80
However,
νd3p: Abbe number for the d-line of at least one positive lens in the 3a lens group. The zoom lens system according to any one of claims 1 to 5,
The zoom lens system in which the 3a lens group and the 3b lens group are separated at a place where the air space is maximum.

Images