JP6015430B2 - Zoom lens system and electronic imaging apparatus including the same - Google Patents

Description

  The present invention relates to a zoom lens system and an electronic image pickup apparatus including the same.

  In recent years, zoom lens systems used in electronic imaging devices such as digital cameras are required to be smaller and have higher performance. The requirements for "high performance" here are specifically that the shortest shooting distance is shorter, the shooting magnification is larger, and the optical performance is better (high-definition and various aberrations can be corrected well). It is. In other words, the term “high performance” as used herein refers to maintaining high optical performance (good optical aberration) over a high imaging magnification (from a long range to a short range).

  In Patent Documents 1-3, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power. A fourth group zoom lens system including the fourth lens group is disclosed.

  The zoom lens system of Patent Document 1 uses a focus lens group that moves the entire second lens group during focusing, and has the advantage of shortening the shortest shooting distance, but the focal length is shortened by the movement of the focusing lens group. Therefore, there is a drawback that the photographing magnification becomes small.

  The zoom lens system of Patent Document 2 has an advantage that the first lens group is divided into a front group and a rear group, and the rear group is a focus lens group that moves during focusing, and the change in focal length due to focusing can be reduced. However, since the shortest shooting distance becomes long, the shooting magnification cannot be increased.

  The zoom lens system of Patent Document 3 is positioned as an improved version of the zoom lens system of Patent Document 2, and like the zoom lens system of Patent Document 2, the first lens group is divided into a front group and a rear group, The rear group is a focus lens group that moves during focusing, and the shortest shooting distance is shortened while maintaining the focal length. However, the optical performance at the shortest shooting distance is insufficient, and in particular, various aberrations such as spherical aberration, coma aberration, and curvature of field occur at the time of near-joining focusing, and the optical performance deteriorates.

JP 2009-42261 A JP 2003-344766 A JP 2008-216480 A

  The present invention has been made on the basis of the above awareness of the problem, and has a zoom lens system having a shortest shooting distance, a large shooting magnification, and excellent optical performance (high-definition and good correction of various aberrations) and the zoom lens system. It is an object to obtain an electronic imaging apparatus provided with

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. And a fourth lens group having a positive refractive power, and at the time of zooming from the short focal length end to the long focal length end, at least the second lens group and the third lens group move, and the distance between the adjacent lens groups In the zoom lens system in which is changed, in order from the object side, the first lens group includes a first-a lens group having a negative refractive power that does not move during focusing and a first-b lens having a positive refractive power that is a focus lens group that moves during focusing. Consisting of a lens group,
The 1b lens group is composed of two positive lenses, and satisfies the following conditional expressions (1) and (2).
(1) 1.2 <f1b / f4 <4.0
(2) -12.0 <f1a / f1 <-2.0
However,
f1: the focal length of the first lens group,
f1a: focal length of the 1a lens group,
f1b: focal length of the 1b lens group,
f4: focal length of the fourth 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. And a fourth lens group having a positive refractive power, and at the time of zooming from the short focal length end to the long focal length end, at least the second lens group and the third lens group move, and the distance between the adjacent lens groups In the zoom lens system in which is changed, in order from the object side, the first lens group includes a first-a lens group having a negative refractive power that does not move during focusing and a first-b lens having a positive refractive power that is a focus lens group that moves during focusing. It consists of a lens group, and satisfies the following conditional expressions (1), (2) and (4 ″).
(1) 1.2 <f1b / f4 <4.0
(2) -12.0 <f1a / f1 <-2.0
(4 ″) − 7.0 <f3 / f2 ≦ −3.12
However,
f1: the focal length of the first lens group,
f1a: focal length of the 1a lens group,
f1b: focal length of the 1b lens group,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
f4: focal length of the fourth lens group,
It is.

Among the condition ranges defined by the conditional expression (1), it is preferable that the following conditional expression (1 ′) is satisfied.
(1 ′) 1.2 <f1b / f4 <3.0

Among the condition ranges defined by the conditional expression (2), it is preferable that the following conditional expression (2 ′) is satisfied.
(2 ′) − 10.0 <f1a / f1 <−3.5

The zoom lens system according to the present invention preferably satisfies the following conditional expression (3).
(3) 80 <ν1b
However,
ν1b: average value of Abbe number with respect to d-line of the positive lens in the 1b lens group,
It is.

  The 1b lens group is preferably composed of two positive lenses.

The zoom lens system according to the present invention preferably satisfies the following conditional expression (4).
(4) -7.0 <f3 / f2 <-3.0
f2: focal length of the second lens group,
f3: focal length of the third lens group,
It is.

Among the condition ranges defined by the conditional expression (4), it is preferable that the following conditional expression (4 ′) is satisfied.
(4 ′) − 5.0 <f3 / f2 <−3.0

  The electronic image pickup apparatus of the present invention includes any one of the zoom lens systems described above and an image pickup element that converts an image formed by the zoom lens system into an electrical signal.

  According to the present invention, it is possible to obtain a zoom lens system having a shortest shooting distance, a large shooting magnification, and excellent optical performance (high definition and excellent correction of various aberrations) and an electronic imaging apparatus including the zoom lens system.

It is a lens block diagram at the time of infinity focusing at the long focal length 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 a short focal length end of the numerical example 1. 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 long 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 short 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 long 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 short 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 long 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 short 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 long 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 short 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 according to 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, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a positive refractive power. The first lens group G1 includes, in order from the object side, a first-a lens group G1a having a negative refractive power and a first-b lens group G1b having a positive refractive power. I is the image plane.

  The zoom lens system according to the present embodiment includes the first lens group G1 and the second lens group G2 during zooming from the short focal length end (Wide) to the long focal length end (Tele) through all numerical examples 1-5. , The distance between the second lens group G2 and the third lens group G3 decreases, and the distance between the third lens group G3 and the fourth lens group G4 decreases. At the time of zooming from the short focal length end to the long focal length end, the distance between the first a lens group G1a and the first b lens group G1b is unchanged.

The first lens group G1 (the 1a lens group G1a and the 1b lens group G1b) and the fourth lens group G4 are subjected to zooming from the short focal length end to the long focal length end through the all numerical examples 1-5. It is fixed with respect to the image plane I (does not move in the optical axis direction). However, a mode in which the first lens group G1 (the first a lens group G1a and the first b lens group G1b) and the fourth lens group G4 move in the optical axis direction upon zooming from the short focal length end to the long focal length end is also possible. It is.
The second lens group G2 monotonously moves to the image side during zooming from the short focal length end to the long focal length end through the whole numerical value example 1-5.
In Numerical Example 1-4, the third lens group G3 monotonously moves to the image side upon zooming from the short focal length end to the long focal length end. In Numerical Example 5, the third lens group G3 is long from the short focal length end. At the time of zooming to the focal length end, it once moves to the image side and then returns to the object side by a slight amount (as a result, it moves to the image side with respect to the short focal length end).

  The 1a lens group G1a is stationary during focusing, and the 1b lens group G1b is a focus lens group that moves during focusing. That is, when focusing from an object at infinity to an object at a finite distance, the 1b lens group G1b moves to the object side.

  The first-a lens group G1a is composed of a cemented lens of a negative lens 11 and a positive lens 12, which are sequentially positioned from the object side, through all numerical value examples 1-5.

  The first lens group G1b is composed of a positive lens 13 and a positive lens 14 in order from the object side through the numerical example 1-5.

  The second lens group G2 includes a negative lens 21, a cemented lens of a negative lens 22 and a positive lens 23, which are sequentially positioned from the object side, and a negative lens 24, in order from the object side, through the numerical example 1-5.

  The third lens group G3 is composed of a cemented lens of a positive lens 31 and a negative lens 32, which are sequentially positioned from the object side, through all numerical value examples 1-5.

  The fourth lens group G4 includes a positive lens 41 in order from the object side, a cemented lens of a positive lens 42 and a negative lens 43, which are sequentially positioned from the object side, a positive lens 44, and a negative lens 45, through all numerical examples 1-5. Consists of.

  The zoom lens system of the present embodiment fixes the first lens group G1 and the fourth lens group G4 to the image plane I upon zooming from the short focal length end to the long focal length end, and mainly the second lens. The group G2 performs zooming, and the third lens group G3 compensates for image plane variation accompanying zooming. Further, the first lens group G1 is divided into a 1a lens group G1a and a 1b lens group G1b, the 1a lens group G1a is fixed during focusing, and the 1b lens group G1b is used as a focus lens group that moves during focusing. Accordingly, it is possible to obtain a zoom lens system in which the entire lens length does not change during zooming and focusing and the F number fluctuates little.

  In the zoom lens system of the present embodiment, the 1a lens group G1a and the 1b lens group G1b have negative refracting power and positive refracting power, respectively, and once divergent by the 1a lens group G1a having negative refracting power. The converged light beam is converged by the first-b lens group G1b having a positive refractive power, thereby succeeding in dramatically shortening the shortest shooting distance and increasing the shooting magnification as compared with the conventional product.

  In the zoom lens system of the present embodiment, the 1b lens group G1b, which is the focus lens group, is composed of two positive lenses 13 and 14, so that the divergent light beam incident from the 1a lens group G1a having a negative refractive power is used. When the lens is converged, the occurrence of spherical aberration or the like can be suppressed and excellent optical performance can be obtained. On the other hand, quick and quiet focusing can be performed without increasing the size and weight of the first lens group G1b which is the focus lens group.

  Furthermore, the zoom lens system according to the present embodiment optimally sets the powers of the first a lens group G1a and the first b lens group G1b constituting the first lens group G1, so that the entire focal length range (the entire zoom range) can be obtained. Corrects various aberrations such as spherical aberration, coma, and field curvature, and reduces fluctuations in spherical aberration and field curvature due to focusing to obtain excellent optical performance (to obtain high-definition images). Has succeeded.

Conditional expression (1) defines the ratio between the focal length of the first lens group G1b, which is the focus lens group, and the focal length of the fourth lens group G4. Satisfying conditional expression (1) suppresses the occurrence of spherical aberration and coma in the entire focal length range (entire zoom range), and reduces the variation of spherical aberration and field curvature due to focusing, resulting in excellent optical performance. (A high-definition image can be obtained).
If the upper limit of conditional expression (1) is exceeded, the power of the fourth lens group G4 becomes too strong, and spherical aberration and coma are likely to occur in the entire focal length range (entire zoom range).
If the lower limit of conditional expression (1) is exceeded, the power of the 1b lens group G1b, which is the focus lens group, becomes too strong, resulting in large variations in spherical aberration and field curvature due to focusing.

Conditional expression (2) defines the ratio between the focal length of the first lens group G1a and the focal length of the first lens group G1. By satisfying conditional expression (2), the field curvature is corrected well, and the spherical aberration and the field curvature variation due to focusing are reduced to obtain excellent optical performance (to obtain a high-definition image). be able to.
If the upper limit of conditional expression (2) is exceeded, the power of the first-a lens group G1a becomes too strong, and the spherical aberration and the variation in field curvature due to focusing become large.
If the lower limit of conditional expression (2) is exceeded, the power of the first-a lens group G1a becomes too weak, and the correction of field curvature becomes insufficient.

Conditional expression (3) defines the average value of the Abbe number for the d-line of the positive lens in the first-b lens group G1b. By satisfying conditional expression (3), chromatic aberration can be favorably corrected particularly at the long focal length end, and excellent optical performance can be obtained (high-definition image can be obtained).
If the lower limit of conditional expression (3) is exceeded, correction of chromatic aberration will be insufficient particularly at the long focal length end.

Conditional expression (4) defines the ratio between the focal length of the third lens group G3 and the focal length of the second lens group G2. By satisfying conditional expression (4), it is possible to suppress fluctuations in astigmatism, coma, and distortion during zooming, and to obtain excellent optical performance (to obtain a high-definition image).
If the upper limit of conditional expression (4) is exceeded, the power of the third lens group G3 becomes too strong, and astigmatism fluctuations at the time of zooming greatly occur.
If the lower limit of conditional expression (4) is exceeded, the power of the second lens group G2 becomes too strong, and fluctuations in coma and distortion at the time of zooming greatly occur.

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 entire system, PM Is the magnification, W is the half field angle (°), Y is the 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]. In all numerical examples 1-5, an aspheric lens is not 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 when focusing at infinity at the long focal length end, FIG. 2 is a diagram showing various aberrations, FIG. 3 is a lateral aberration diagram, and FIG. 4 is a diagram when focusing at infinity at the short focal length end. 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. And a fourth lens group G4 having a positive refractive power. A diaphragm S positioned between the second lens group G2 and the third lens group G3 moves integrally with the third lens group G3. An optical filter OP is arranged between the fourth lens group G4 and the image plane I.

The first lens group G1 includes, in order from the object side, a first-a lens group G1a having a negative refractive power and a first-b lens group G1b having a positive refractive power. The 1a lens group G1a is stationary during focusing, and the 1b lens group G1b is a focus lens group that moves during focusing. That is, when focusing from an object at infinity to an object at a finite distance, the 1b lens group G1b moves to the object side.
The first-a lens group G1a is composed of a cemented lens of a biconcave negative lens 11 and a biconvex positive lens 12 that are sequentially located from the object side.
The first-b lens group G1b includes, in order from the object side, a biconvex positive lens 13 and a positive meniscus lens 14 convex on the object side.

  The second lens group G2 includes, from the object side, a biconcave negative lens 21, a cemented lens of a biconcave negative lens 22 positioned in order from the object side, a positive meniscus lens 23 convex to the object side, and a biconcave negative lens 24. Become.

  The third lens group G3 includes a cemented lens including a biconvex positive lens 31 positioned in order from the object side and a negative meniscus lens 32 convex toward the image side.

  The fourth lens group G4 includes, in order from the object side, a positive meniscus lens 41 that is convex toward the object side, a cemented lens of a biconvex positive lens 42 and a biconcave negative lens 43 that are sequentially positioned from the object side, a biconvex positive lens 44, and It consists of a negative meniscus lens 45 convex on the image side.

(Table 1)
Surface data surface number R d N (d) ν (d)
1 -1449.985 1.00 1.80440 39.6
2 40.067 4.94 1.49700 81.6
3 -84.919 9.40
4 37.911 4.21 1.49700 81.6
5 -143.485 0.10
6 39.011 2.78 1.43875 95.0
7 93.586 d7
8 -64.900 0.90 1.81600 46.6
9 42.052 0.66
10 -32.216 1.00 1.72916 54.7
11 8.560 2.33 1.84666 23.8
12 49.280 0.42
13 -76.078 0.90 1.80 400 46.6
14 37.657 d14
15 stops ∞ 1.00
16 98.777 2.00 1.63930 44.9
17 -10.134 0.90 1.80518 25.4
18 -21.988 d18
19 13.683 3.01 1.80440 39.6
20 90.519 0.33
21 14.614 2.89 1.49700 81.6
22 -21.390 3.52 1.71736 29.5
23 9.221 2.73
24 19.286 3.03 1.80 400 46.6
25 -28.010 1.18
26 -11.325 1.53 1.83400 37.2
27 -19.280 9.93
28 ∞ 1.00 1.51633 64.1
29 ∞-
(Table 2)
Various data zoom ratio (magnification ratio) 2.88
Minimum focusing distance 390
Maximum magnification -0.17
When focusing on an object at infinity Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.3 3.4
f 15.30 26.00 44.10
PM 0.000 0.000 0.000
W 18.9 10.8 6.3
Y 5.00 5.00 5.00
fB 2.58 2.58 2.58
L 87.04 87.04 87.04
d7 3.01 13.30 20.47
d14 5.53 4.55 1.25
d18 14.22 4.92 1.05
When focusing on a short distance object (shortest distance object) Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.3 3.4
f 20.31 36.10 55.18
PM -0.060 -0.102 -0.173
W 13.5 7.1 4.0
Y 5.00 5.00 5.19
fB 2.58 2.58 2.58
L 87.04 87.04 87.04
d7 11.40 21.68 28.85
d14 5.53 4.55 1.25
d18 14.22 4.92 1.05
(Table 3)
Lens group data group Start surface Focal length
1 1 45.58
2 8 -10.32
3 16 37.40
4 19 20.22

[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 long focal length end, FIG. 8 is a diagram of various aberrations, FIG. 9 is a diagram of its lateral aberration, and FIG. 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.

(Table 4)
Surface data surface number R d N (d) ν (d)
1 -144.641 1.00 1.76200 40.1
2 46.578 5.79 1.49700 81.6
3 -60.065 10.36
4 41.262 4.21 1.49700 81.6
5 -136.363 0.10
6 32.169 2.60 1.43875 95.0
7 56.993 d7
8 -51.585 0.90 1.81600 46.6
9 42.762 0.64
10 -46.047 1.00 1.80 400 46.6
11 9.193 2.34 1.84666 23.8
12 103.910 0.32
13 -220.807 0.90 1.81600 46.6
14 49.143 d14
15 stops ∞ 1.00
16 407.570 1.73 1.63930 44.9
17 -13.820 0.90 1.80518 25.4
18 -29.609 d18
19 11.893 3.62 1.80 400 46.6
20 122.357 0.40
21 11.642 3.09 1.49700 81.6
22 -22.383 3.98 1.90366 31.3
23 7.915 1.33
24 12.386 4.00 1.80 400 46.6
25 -26.942 0.89
26 -8.288 1.00 1.88300 40.8
27 -16.206 7.40
28 ∞ 1.20 1.51633 64.1
29 ∞-
(Table 5)
Various data zoom ratio (magnification ratio) 2.86
Minimum focusing distance 390
Maximum magnification -0.17
When focusing on an object at infinity Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.4 3.6
f 15.40 26.00 44.00
PM 0.000 0.000 0.000
W 18.7 10.8 6.3
Y 5.00 5.00 5.00
fB 2.45 2.45 2.45
L 86.76 86.76 86.76
d7 3.43 13.99 21.60
d14 5.86 5.67 1.25
d18 14.33 3.95 0.77
When focusing on a short distance object (shortest distance object) Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.4 3.6
f 20.39 34.70 48.85
PM -0.061 -0.103 -0.174
W 13.3 7.1 4.0
Y 5.00 5.00 5.19
fB 2.45 2.45 2.45
L 86.76 86.76 86.76
d7 12.78 23.34 30.95
d14 5.86 5.67 1.25
d18 14.33 3.95 0.77
(Table 6)
Lens group data group Start surface Focal length
1 1 47.82
2 8 -12.36
3 16 59.26
4 19 17.73

[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 long focal length end, FIG. 14 is a diagram showing various aberrations thereof, FIG. 15 is a diagram showing its lateral aberration, 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 negative lens 11 of the first lens group G1 (first a lens group G1a) is a negative meniscus lens convex toward the object side.
(2) The stop S is located in the optical axis orthogonal plane in contact with the most object side surface of the fourth lens group G4 (the object side surface of the positive meniscus lens 41), and the stop S is in the fourth lens group G4. And move together.

(Table 7)
Surface data surface number R d N (d) ν (d)
1 195.151 1.00 1.83400 37.3
2 30.852 5.19 1.49700 81.6
3 -336.779 9.03
4 35.949 4.91 1.49700 81.6
5 -119.284 0.10
6 38.198 3.36 1.49700 81.6
7 174.882 d7
8 -93.416 0.90 1.72916 54.7
9 29.251 0.75
10 -41.044 1.00 1.72916 54.7
11 8.520 2.39 1.84666 23.8
12 45.475 0.53
13 -29.563 0.90 1.72916 54.7
14 39.253 d14
15 98.290 2.70 1.63930 44.9
16 -9.775 0.90 1.80518 25.5
17 -22.511 d17
18 stops ∞ 0.00
19 14.793 2.82 1.74330 49.2
20 90.795 3.69
21 13.123 3.39 1.49700 81.6
22 -15.516 1.40 1.62004 36.3
23 9.477 0.88
24 19.800 2.29 1.80420 46.5
25 -35.443 1.39
26 -10.762 3.30 1.84666 23.8
27 -16.103 12.00
28 ∞ 1.20 1.51633 64.1
29 ∞-
(Table 8)
Various data zoom ratio (magnification ratio) 2.88
Minimum focusing distance 390
Maximum magnification -0.17
When focusing on an object at infinity Short focal length end Intermediate focal length Long focal length end
FNO. 3.5 3.6 3.6
f 15.30 26.00 44.10
PM 0.000 0.000 0.000
W 18.9 10.9 6.3
Y 5.00 5.00 5.00
fB 1.36 1.36 1.36
L 89.09 89.09 89.09
d7 3.53 12.34 18.46
d14 6.68 5.91 2.65
d17 11.50 3.46 0.60
When focusing on a short distance object (shortest distance object) Short focal length end Intermediate focal length Long focal length end
FNO. 3.6 3.6 3.5
f 20.42 36.40 56.89
PM -0.060 -0.102 -0.172
W 13.5 7.0 3.9
Y 5.00 5.00 5.19
fB 1.36 1.36 1.36
L 89.09 89.09 89.09
d7 10.56 19.38 25.49
d14 6.68 5.91 2.65
d17 11.50 3.46 0.60
(Table 9)
Lens group data group Start surface Focal length
1 1 40.60
2 8 -9.34
3 15 39.55
4 19 20.08

[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 long focal length end, FIG. 20 is a diagram of various aberrations thereof, FIG. 21 is a diagram of its lateral aberration, and FIG. 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.

(Table 10)
Surface data surface number R d N (d) ν (d)
1 -172.685 1.00 1.80440 39.6
2 40.134 5.19 1.49700 81.6
3 -91.688 9.06
4 45.629 4.91 1.49700 81.6
5 -85.652 0.10
6 33.326 3.36 1.49700 81.6
7 132.908 d7
8 -87.641 0.90 1.72916 54.7
9 38.813 0.50
10 -36.729 1.00 1.72916 54.7
11 9.170 2.42 1.84666 23.8
12 34.120 0.55
13 -41.139 0.90 1.72916 54.7
14 51.324 d14
15 stops ∞ 1.00
16 109.013 2.06 1.66998 39.3
17 -9.990 0.90 1.80518 25.4
18 -24.847 d18
19 14.342 2.53 1.72916 54.7
20 83.761 2.40
21 13.037 3.99 1.49700 81.6
22 -17.163 1.40 1.62004 36.3
23 9.005 0.75
24 18.995 3.16 1.77250 49.6
25 -38.844 1.70
26 -9.487 3.01 1.84666 23.8
27 -13.465 11.00
28 ∞ 1.20 1.51633 64.1
29 ∞-
(Table 11)
Various data zoom ratio (magnification ratio) 2.88
Minimum focusing distance 390
Maximum shooting magnification -0.18
When focusing on an object at infinity Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.3 3.4
f 15.30 26.00 44.10
PM 0.000 0.000 0.000
W 19.0 10.9 6.3
Y 5.00 5.00 5.00
fB 1.87 1.87 1.87
L 88.29 88.29 88.29
d7 3.57 13.17 19.88
d14 5.49 4.55 0.95
d18 12.38 3.71 0.60
When focusing on a short distance object (shortest distance object) Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 3.3 3.4
f 20.81 36.55 55.16
PM -0.062 -0.105 -0.177
W 13.3 7.1 4.0
Y 5.00 5.00 5.19
fB 1.87 1.87 1.87
L 88.29 88.29 88.29
d7 11.63 21.24 27.94
d14 5.49 4.55 0.95
d18 12.38 3.71 0.60
(Table 12)
Lens group data group Start surface Focal length
1 1 41.55
2 8 -10.25
3 16 40.01
4 19 20.21

[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 long focal length end, FIG. 26 is a diagram showing various aberrations thereof, FIG. 27 is a lateral aberration diagram thereof, 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) In the first lens group G1 (first a lens group G1a), the negative lens 11 is a negative meniscus lens convex toward the object side, and the positive lens 12 is a positive meniscus lens convex toward the object side.
(2) The positive lens 41 of the fourth lens group G4 is a biconvex positive lens.

(Table 13)
Surface data surface number R d N (d) ν (d)
1 63.094 1.00 1.80610 33.3
2 22.087 5.19 1.51633 64.1
3 74.137 15.06
4 35.603 5.29 1.49700 81.6
5 -69.913 0.10
6 30.336 3.36 1.49700 81.6
7 128.938 d7
8 -59.826 0.90 1.83481 42.7
9 31.712 0.83
10 -34.682 1.00 1.72916 54.7
11 8.299 2.51 1.84666 23.8
12 43.742 0.52
13 -46.032 0.90 1.80 400 46.6
14 37.926 d14
15 stop ∞ 1.20
16 37.722 2.70 1.67790 55.3
17 -8.273 0.90 1.83400 37.2
18 -21.674 d18
19 16.006 2.27 1.77250 49.6
20 -184.406 1.71
21 14.681 3.09 1.49700 81.6
22 -17.355 1.00 1.66680 33.0
23 10.109 5.14
24 17.751 3.23 1.74 100 52.7
25 -45.935 1.02
26 -13.910 0.90 1.78472 25.7
27 -38.084 6.00
28 ∞ 1.20 1.51633 64.1
29 ∞-
(Table 14)
Various data zoom ratio (magnification ratio) 2.86
Minimum focusing distance 390
Maximum shooting magnification -0.14
When focusing on an object at infinity Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 2.9 2.9
f 13.30 24.02 38.03
PM 0.000 0.000 0.000
W 22.0 11.8 7.3
Y 5.00 5.00 5.00
fB 1.45 1.46 1.46
L 86.58 86.58 86.58
d7 2.50 11.40 15.66
d14 7.76 4.99 1.25
d18 7.86 1.71 1.19
When focusing on a short distance object (shortest distance object) Short focal length end Intermediate focal length Long focal length end
FNO. 2.8 2.9 2.9
f 16.49 30.74 44.83
PM -0.049 -0.088 -0.140
W 16.9 8.4 5.2
Y 5.00 5.00 5.19
fB 1.46 1.46 1.46
L 86.58 86.58 86.58
d7 7.15 16.06 20.32
d14 7.74 4.99 1.25
d18 7.86 1.71 1.19
(Table 15)
Lens group data group Start surface Focal length
1 1 33.85
2 8 -8.65
3 16 27.01
4 19 21.63

Table 16 shows values for the conditional expressions of the numerical examples.
(Table 16)
Example 1 Example 2 Example 3
Conditional expression (1) 2.15 2.60 1.80
Conditional expression (2) -9.90 -9.90 -4.81
Conditional expression (3) 88.3 88.3 81.6
Conditional expression (4) -3.63 -4.79 -4.23
Example 4 Example 5
Conditional expression (1) 1.80 1.40
Conditional expression (2) -3.61 -4.12
Conditional expression (3) 81.6 81.6
Conditional expression (4) -3.90 -3.12

  As apparent from Table 16, Numerical Example 1 to Numerical Example 5 satisfy the conditional expressions (1) to (4), and various aberrations and lateral aberrations are apparent from the various aberration diagrams and lateral aberration diagrams. 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 claims of the present invention, the technical scope of the present invention is not avoided.

G1 first lens group G1a having positive refractive power 1a lens group 11 having negative refractive power 11 negative lens 12 positive lens G1b first b lens group 13 having positive refractive power 13 positive lens 14 positive lens G2 second lens having negative refractive power Lens group 21 Negative lens 22 Negative lens 23 Positive lens 24 Negative lens G3 Third lens group 31 with positive refractive power Positive lens 32 Negative lens G4 Fourth lens group 41 with positive refractive power 41 Positive lens 42 Positive lens 43 Negative lens 44 Positive lens 45 Negative lens S Aperture OP Optical filter I Image plane

Claims (6)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. In the zoom lens system in which at least the second lens unit and the third lens unit move and the interval between adjacent lens units changes during zooming from the short focal length end to the long focal length end,
The first lens group includes, in order from the object side, a first-a lens group having a negative refractive power that does not move during focusing, and a first-b lens group having a positive refractive power that is a focus lens group that moves during focusing.
The zoom lens system is characterized in that the first lens group is composed of two positive lenses and satisfies the following conditional expressions (1) and (2).
(1) 1.2 <f1b / f4 <4.0
(2) -12.0 <f1a / f1 <-2.0
However,
f1: the focal length of the first lens group,
f1a: focal length of the 1a lens group,
f1b: focal length of the 1b lens group,
f4: Focal length of the fourth lens group. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. In the zoom lens system in which at least the second lens unit and the third lens unit move and the interval between adjacent lens units changes during zooming from the short focal length end to the long focal length end,
The first lens group includes, in order from the object side, a first-a lens group having negative refractive power that does not move during focusing, and a first-b lens group having positive refractive power that is a focus lens group that moves during focusing; and
A zoom lens system characterized by satisfying the following conditional expressions (1), (2) and (4 ″):
(1) 1.2 <f1b / f4 <4.0
(2) -12.0 <f1a / f1 <-2.0
(4 ″) − 7.0 <f3 / f2 ≦ −3.12
However,
f1: the focal length of the first lens group,
f1a: focal length of the 1a lens group,
f1b: focal length of the 1b lens group,
f2: focal length of the second lens group,
f3: focal length of the third lens group,
f4: Focal length of the fourth lens group. 3. The zoom lens system according to claim 2 , wherein the 1b lens group includes two positive lenses. 2. The zoom lens system according to claim 1, wherein the zoom lens system satisfies the following conditional expression (4).
(4) -7.0 <f3 / f2 <-3.0
f2: focal length of the second lens group,
f3: focal length of the third lens group. The zoom lens system according to any one of claims 1 to 4, wherein the zoom lens system satisfies the following conditional expression (3).
(3) 80 <ν1b
However,
ν1b: Average value of the Abbe number with respect to the d-line of the positive lens in the 1b lens group. 6. An electronic imaging apparatus comprising: the zoom lens system according to claim 1; and an imaging element that converts an image formed by the zoom lens system into an electrical signal.

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