JP2013228500A - Zoom lens system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small zoom lens having high variable power with a variable power ratio as high as about 28 to 30 times, and reduced in the entire length of the lens.SOLUTION: A zoom lens system comprises, in order from an object side, a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group. When a power varies from a wide end to a tele-end, the interval between the first lens group and the second lens group increases, and the interval between the second lens group and the third lens group decreases. In the zoom lens system, the following formulae are satisfied: (1)0.10<|d23t-d23w|/ft<0.20 and (2)2.50<ft/f1<5.00, where d23t is the air interval between the second lens group and the third lens group at a long focal distance end, d23w is the air interval between the second lens group and the third lens group at a short focal distance end, ft is the focal distance of the entire system at the long focal distance end, and f1 is the focal distance of the first lens group.

Description

  The present invention relates to a zoom lens system.

  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 fourth lens having a negative refractive power. A zoom lens system including a lens group and a fifth lens group having a positive refractive power is disclosed.

  However, in all zoom lens systems disclosed in Patent Documents 1-3, the zoom ratio is 20 times or less, and the high zoom ratio is insufficient. Further, since the amount of movement (distance change) of the second lens group and the third lens group on the optical axis at the time of zooming is too large, the total lens length (especially the retracted length during storage) becomes long. Further, since the amount of movement (the amount of extension) of the first lens unit on the optical axis at the time of zooming is too large, the distance between the first lens unit and the second lens unit is widened especially at the long focal length end, and the total lens length is long. turn into.

JP 2011-186417 A JP 2011-232543 A JP 2011-252962 A

  The present invention has been completed based on the above awareness of the problems, and achieves a high zooming ratio with a zoom ratio of about 28 to 30 times, and obtains a compact zoom lens system in which the total lens length is shortened. For the purpose.

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, a third lens group having a positive refractive power, and a fourth lens having a negative refractive power. A lens unit and a fifth lens unit having a positive refractive power, and the distance between the first lens unit and the second lens unit increases upon zooming from the short focal length end to the long focal length end, and the second lens group In the zoom lens system in which the distance between the first lens unit and the third lens unit is reduced, the following conditional expressions (1) and (2) are satisfied.
(1) 0.10 <| d23t−d23w | / ft <0.20
(2) 2.50 <ft / f1 <5.00
However,
d23t: the air space between the second lens group and the third lens group at the long focal length end,
d23w: the air space between the second lens group and the third lens group at the short focal length end,
ft: focal length of the entire system at the long focal length end,
f1: the focal length of the first lens group,
It is.

In the zoom lens system according to the present invention, the first lens group includes three lenses, a negative lens, a positive lens, and a positive lens, in order from the object side, and satisfies the following conditional expressions (3) and (4). It is preferable.
(3) LPνd> 95
(4) LNνd> 39
However,
LPνd: Abbe number of the positive lens on the object side in the first lens group with respect to the d-line,
LNνd: Abbe number for the d-line of the negative lens in the first lens group,
It is.

The zoom lens system according to the present invention preferably satisfies the following conditional expression (5).
(5) 7.5 <m2t / m2w <15.0
However,
m2t: lateral magnification of the second lens group at the time of focusing at infinity at the long focal length end,
m2w: lateral magnification of the second lens group at the time of focusing at infinity at the short focal length end,
It is.

  In the zoom lens system of the present invention, the second lens group is configured by four lenses of a negative lens in order from the object side, a cemented lens of a positive lens and a negative lens positioned in order from the object side, and a negative lens. One lens can be an aspheric lens.

  Alternatively, in the zoom lens system according to the present invention, the second lens group includes four lenses of a negative lens, a negative lens, a positive lens, and a negative lens in order from the object side, and at least one lens is an aspheric lens. It can be.

The zoom lens system according to the present invention preferably satisfies the following conditional expression (6).
(6) -0.92 <f2p / f2 <-0.65
However,
f2p: the focal length of the positive lens in the second lens group,
f2: focal length of the second lens group,
It is.

In the zoom lens system according to the present invention, it is preferable that the fifth lens group is a focus lens group that moves during focusing, and the following conditional expression (7) is satisfied.
(7) 8.5 <ft / f5 <20.0
However,
ft: focal length of the entire system at the long focal length end,
f5: focal length of the fifth lens group,
It is.

  The zoom lens system of the present invention preferably forms a focus lens group in which both the fourth lens group and the fifth lens group move during focusing in at least a part of the zooming region.

  In the zoom lens system of the present invention, the third lens group is arranged in order from the object side, the positive lens, the cemented lens of the positive lens and the negative lens positioned in order from the object side, and four lenses of the positive lens, or the object side. In this order, the lens can be composed of three lenses: a positive lens, a negative lens, and a positive lens.

  In the zoom lens system of the present invention, the fourth lens group includes a negative single lens, a cemented lens of a negative lens and a positive lens positioned in order from the object side, a cemented lens of a positive lens and a negative lens positioned in order from the object side, or In order from the object side, the lens can be composed of a cemented lens of a positive lens and a negative lens, and a positive lens that are positioned in order from the object side.

  According to the present invention, it is possible to obtain a small zoom lens system in which a high zoom ratio of about 28 to 30 times is achieved and the total lens length is shortened.

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 of various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as shown in FIG. 1. FIG. 2 is a diagram showing various aberrations when focusing at infinity at an intermediate focal length of the zoom lens system configured as shown in FIG. 1. FIG. 2 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as shown in FIG. 1. 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. 6 is a diagram of various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as shown in FIG. 5. FIG. 6 is a diagram of various aberrations at the time of focusing on infinity at an intermediate focal length of the zoom lens system configured as shown in FIG. 5. FIG. 6 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as shown in FIG. 5. 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. 10 is a diagram illustrating various aberrations at the time of focusing at infinity at the short focal length end of the zoom lens system configured as illustrated in FIG. 9. FIG. 10 is a diagram illustrating various aberrations when the zoom lens system configured as illustrated in FIG. 9 is focused at infinity at an intermediate focal length. FIG. 10 is a diagram illustrating various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as illustrated in FIG. 9. 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. 14 is a diagram of various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as illustrated in FIG. 13. FIG. 14 is a diagram illustrating various aberrations when the zoom lens system configured as illustrated in FIG. 13 is focused at infinity at an intermediate focal length. FIG. 14 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as illustrated in FIG. 13. 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. 18 is a diagram of various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as shown in FIG. 17. FIG. 18 is a diagram illustrating various aberrations when the zoom lens system configured as illustrated in FIG. 17 is focused at infinity at an intermediate focal length. FIG. 18 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as illustrated in FIG. 17. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 6 of the zoom lens system by the present invention. FIG. 22 is a diagram of various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as shown in FIG. 21. FIG. 22 is a diagram of various aberrations at the time of focusing on infinity at the intermediate focal length of the zoom lens system configured as shown in FIG. 21. FIG. 22 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as shown in FIG. 21. It is a lens block diagram at the time of infinity focusing in the short focal distance end of Numerical Example 7 of the zoom lens system by the present invention. FIG. 26 is a diagram illustrating various aberrations at the time of focusing on infinity at the short focal length end of the zoom lens system configured as illustrated in FIG. 25. FIG. 26 is a diagram illustrating various aberrations when the zoom lens system configured as illustrated in FIG. 25 is focused at infinity at an intermediate focal length. FIG. 26 is a diagram of various aberrations at the time of focusing on infinity at the long focal length end of the zoom lens system configured as shown in FIG. 25. 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. It consists of a second lens group G2, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a negative refractive power, and a fifth lens group G5 having a positive refractive power.

  In the zoom lens system according to the present embodiment, the first lens group G1 and the second lens group are zoomed from the short focal length end (Wide) to the long focal length end (Tele) through all numerical examples 1-7. The distance between the lens group G2 increases, the distance between the second lens group G2 and the third lens group G3 decreases, the distance between the third lens group G3 and the fourth lens group G4 increases, and the fourth lens group G4 and the fourth lens group G4 increase. All the lens groups of the first lens group G1 to the fifth lens group G5 move so that the interval between the five lens groups G5 increases.

  More specifically, upon zooming from the short focal length end to the long focal length end, the first lens group G1 monotonously moves to the object side, the second lens group G2 monotonously moves to the image side, The third lens group G3 moves to the object side while drawing a convex locus on the object side, the fourth lens group G4 moves to the object side while drawing a convex locus on the object side, and the fifth lens group G5 is monotonously imaged. Move to the side. However, the movement locus of the first lens group G1 to the fifth lens group G5 has a degree of freedom.

  The first lens group G1 is composed of three lenses, a negative lens 11, a positive lens 12, and a positive lens 13, in order from the object side, through all numerical value examples 1-7. The negative lens 11 and the positive lens 12 are not joined in Numerical Example 1-6, but are joined in Numerical Example 7.

In Numerical Example 1-4, the second lens group G2 includes four lenses, ie, a negative lens 21, sequentially from the object side, a cemented lens of the positive lens 22 and the negative lens 23 that are sequentially positioned from the object side, and a negative lens 24. Consists of. The negative lens 24 has two aspheric surfaces.
In Numerical Example 5-7, the second lens group G2 is composed of four lenses, a negative lens 21 ′, a negative lens 22 ′, a positive lens 23 ′, and a negative lens 24 ′, sequentially from the object side. The positive lens 23 'has an aspheric surface on the object side.

In Numerical Example 1-6, the third lens group G3 includes four lenses: a positive lens 31, sequentially from the object side, a cemented lens of the positive lens 32 and the negative lens 33, which are sequentially positioned from the object side, and a positive lens 34. Consists of. The positive lens 31 has two aspheric surfaces.
In Numerical Example 7, the third lens group G3 includes three lenses, a positive lens 31 ′, a negative lens 32 ′, and a positive lens 33 ′, sequentially from the object side. The positive lens 31 ′ has two aspheric surfaces.

In Numerical Example 1, the fourth lens group G4 includes a cemented lens of a negative lens 41 and a positive lens 42 that are sequentially positioned from the object side.
In Numerical Example 2-4, the fourth lens group G4 includes a cemented lens of a positive lens 41 ′ and a negative lens 42 ′ that are sequentially disposed from the object side. In the numerical examples 2 and 4, the positive lens 41 ′ is spherical on both surfaces, and in the numerical example 3, the object side surface is aspheric.
In Numerical Example 5, the fourth lens group G4 includes three lenses, a cemented lens of a positive lens 41 ″ and a negative lens 42 ″, which are sequentially positioned from the object side, and a positive lens 43 ″. Consists of. The positive lens 41 ″ has an aspheric surface on the object side, and the positive lens 43 ″ has an aspheric surface on the image side.
The fourth lens group G4 includes a negative single lens 41 ′ ″ in Numerical Examples 6 and 7.

  The fifth lens group G5 is composed of a positive single lens 51 having aspheric surfaces on both surfaces, through all numerical value examples 1-7.

  The zoom lens system according to the present embodiment 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, a third lens group G3 having a positive refractive power, and a negative refraction. In a five-group zoom lens configuration comprising a fourth lens group G4 having a positive power and a fifth lens group G5 having a positive refractive power, the power of the first lens group G1, the second lens group G2 and the third lens at the time of zooming Optimum setting of the gap change of the group G3 achieves a high zoom ratio of 28 to 30 times and a reduction in the total lens length at the same time as well as excellent correction of various aberrations. Has succeeded in obtaining performance.

Conditional expression (1) defines the change in the distance between the second lens group G2 and the third lens group G3 during zooming. By satisfying conditional expression (1), it is possible to shorten the overall lens length (especially the retracted length during storage) and to excellently correct coma and lateral chromatic aberration, thereby obtaining excellent optical performance.
If the upper limit of conditional expression (1) is exceeded, the change in the distance between the second lens group G2 and the third lens group G3 at the time of zooming becomes too large, and the total lens length (especially the retracted length during storage) becomes long.
If the lower limit of conditional expression (1) is exceeded, correction of coma and lateral chromatic aberration will be difficult, and optical performance will deteriorate. In addition, the assembly sensitivity increases and the manufacturing difficulty level increases.

Conditional expression (2) defines the ratio between the focal length of the entire system at the long focal length end and the focal length of the first lens group G1. By satisfying conditional expression (2), it is possible to achieve both high zoom ratio and shortening of the overall lens length, and excellent correction of various aberrations to obtain excellent optical performance.
If the upper limit of conditional expression (2) is exceeded, the power of the first lens group G1 becomes too strong, making it difficult to correct aberrations.
If the lower limit of conditional expression (2) is exceeded, the power of the first lens group G1 becomes too weak, and the moving amount (feeding amount) of the first lens group on the optical axis is increased for high zooming. Therefore, the distance between the first lens group and the second lens group is widened particularly at the end of the long focal length, and the entire lens length becomes long.

As described above, the first lens group G1 includes the three lenses of the negative lens 11, the positive lens 12, and the positive lens 13 in order from the object side through the numerical example 1-7.
In this configuration, the conditional expression (3) defines the Abbe number with respect to the d-line of the object side positive lens 12 in the first lens group G1, and the conditional expression (4) is in the first lens group G1. The Abbe number for the d-line of the negative lens 11 is defined. By satisfying conditional expressions (3) and (4), it is possible to satisfactorily correct chromatic aberration in the first lens group G1 and obtain excellent optical performance.
If the lower limit of conditional expressions (3) and (4) is exceeded, the chromatic aberration in the first lens group G1 will be difficult to correct and the optical performance will deteriorate.

Conditional expression (5) defines the change in the lateral magnification of the second lens group G2 upon zooming from the short focal length end to the long focal length end, that is, the zooming burden of the second lens group G2. . By satisfying the conditional expression (5), it is possible to achieve high zooming and excellent optical performance by satisfactorily correcting coma and the like.
If the upper limit of conditional expression (5) is exceeded, the variable magnification burden of the second lens group G2 becomes too large, and in particular, coma becomes difficult to correct and optical performance deteriorates.
If the lower limit of conditional expression (5) is exceeded, the zooming burden of the second lens group G2 will be too small, and high zooming will not be obtained.

As described above, in the numerical example 1-4, the second lens group G2 includes, in order from the object side, the negative lens 21, the cemented lens of the positive lens 22 and the negative lens 23 that are positioned in order from the object side, and the negative lens 24. The negative lens 24 is an aspherical lens.
By joining the positive lens 22 and the negative lens 23, the decentering sensitivity of the second lens group G2 can be reduced, which is advantageous in manufacturing. Further, by including an aspheric lens in the second lens group G2, off-axis aberrations can be favorably corrected.

As described above, in the numerical example 5-7, the second lens group G2 includes four lenses of the negative lens 21 ′, the negative lens 22 ′, the positive lens 23 ′, and the negative lens 24 ′ in order from the object side. Among these, the positive lens 23 'is an aspherical lens.
By sequentially arranging two negative lenses 21 ′ and 22 ′ in order from the object side in the second lens group G2, the light rays incident on the second lens group G2 from the first lens group G1 are converted into the subsequent lens group ( It is possible to disperse the strong negative refractive power necessary for transmission to the third lens group G3, the fourth lens group G4, and the fifth lens group G5). Further, by including an aspheric lens in the second lens group G2, off-axis aberrations can be favorably corrected.

Conditional expression (6) is the ratio of the focal length of the positive lens 22 or the positive lens 23 ′ of the second lens group G2 and the focal length of the second lens group G2 in the second lens group G2 described above. It stipulates. By satisfying conditional expression (6), it is possible to satisfactorily correct field curvature and chromatic aberration and obtain excellent optical performance.
If the upper limit of conditional expression (6) is exceeded, the power of the positive lens 22 or the positive lens 23 ′ of G2 in the second lens group will be too strong, making it difficult to correct field curvature.
When the lower limit of conditional expression (6) is exceeded, the power of the positive lens 22 or the positive lens 23 ′ of G2 in the second lens group becomes too weak, making it difficult to correct chromatic aberration.

In the zoom lens system of the present embodiment, the fifth lens group G5 constitutes a focus lens group that moves during focusing.
Conditional expression (7) defines the ratio between the focal length of the entire system at the long focal length end and the focal length of the fifth lens group G5 in this configuration. By satisfying conditional expression (7), it is possible to obtain excellent optical performance by suppressing aberration fluctuations during focusing, and to reduce the total lens length by suppressing the focusing movement amount of the fifth lens group G5.
If the upper limit of conditional expression (7) is exceeded, the power of the fifth lens group G5, which is the focus lens group, becomes too strong, and aberration fluctuations during focusing become large.
If the lower limit of conditional expression (7) is exceeded, the power of the fifth lens group G5, which is the focus lens group, becomes too weak, and the amount of focusing movement increases and the total lens length becomes longer.

  Further, in the zoom lens system of the present embodiment, when focusing from an object at infinity to an object at a finite distance, both the fourth lens group G4 and the fifth lens group G5 constitute a focus lens group in at least a part of the zooming area. This makes it possible to improve the short distance performance over the entire zoom range and to reduce the size of the lens system. Further, as in the numerical examples 6 and 7, the fourth lens group G4 and the fifth lens group G5, which are focus lens groups, are composed of the negative single lens 41 ′ ″ and the positive single lens 51, so that the focus driving mechanism is achieved. This makes it possible to achieve quick focusing.

Next, specific numerical examples will be shown. In the 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, and W is the half angle of view. (゜), 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 distance, N (d) is the refractive index for the d-line, νd is the Abbe number for the d-line, and “Ea” is “× 10 ^−a Is shown. The unit of length is [mm]. 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.
A rotationally symmetric aspherical surface is defined by
x = cy ² / [1+ [1- (1 + K) c ² y ² ] ^1/2 ] + A4y ⁴ + A6y ⁶ + A8y ⁸ + A10y ¹⁰ + A12y ^{12 ...}
(Where c is the curvature (1 / r), y is the height from the optical axis, K is the conic coefficient, A4, A6, A8,... Are the aspheric coefficients of each order, and x is the sag amount)

[Numerical Example 1]
1 to 4 and Tables 1 to 4 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. 2, 3 and 4 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 1 shows surface data, Table 2 shows various data, Table 3 shows aspherical data, and Table 4 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, a third lens group G3 having a positive refractive power, and a negative The fourth lens group G4 having a refractive power of 5 and the fifth lens group G5 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 disposed behind the fifth lens group G5 (between the image plane I).

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

  The second lens group G2 includes, in order from the object side, a biconcave negative lens 21, a cemented lens of a biconvex positive lens 22 and a biconcave negative lens 23 sequentially located from the object side, and a negative meniscus lens 24 convex to the image side. Become. The negative meniscus lens 24 has two aspheric surfaces.

  The third lens group G3 includes, in order from the object side, a biconvex positive lens 31, a cemented lens of a positive meniscus lens 32 convex toward the object side and a negative meniscus lens 33 convex toward the object side, and biconvex. It consists of a positive lens 34. The biconvex positive lens 31 has two aspheric surfaces.

  The fourth lens group G4 includes a cemented lens of a biconcave negative lens 41 positioned in order from the object side and a positive meniscus lens 42 convex toward the object side.

  The fifth lens group G5 includes a biconvex positive single lens 51 having both aspheric surfaces.

(Table 1)
Surface data surface number rd N (d) νd
1 66.162 0.800 1.80450 39.6
2 22.406 0.180
3 22.683 3.822 1.43700 95.1
4 -225.563 0.100
5 24.200 3.251 1.61800 63.4
6 1584.311 d6
7 -144.706 0.700 1.88300 40.8
8 6.968 1.894
9 45.561 2.531 1.92286 20.9
10 -8.694 0.600 1.83481 42.7
11 70.724 0.837
12 * -20.208 0.700 1.83441 37.3
13 * -500.000 d13
14 stop ∞ 0.200
15 * 6.086 2.000 1.61881 63.8
16 * -25.931 0.100
17 13.305 1.262 1.49700 81.6
18 79.394 0.600 1.80610 33.3
19 5.127 0.366
20 8.573 1.502 1.61800 63.4
21 -22.810 d21
22 -69.380 0.500 1.80420 46.5
23 5.097 1.186 1.59551 39.2
24 11.136 d24
25 * 36.054 2.548 1.53110 55.9
26 * -9.428 d26
27 ∞ 0.800 1.51680 64.2
28 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 2)
Various data zoom ratio (magnification ratio) 28.27
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 5.3 6.5
f 4.61 23.99 130.37
W 41.4 9.2 1.7
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 57.33 71.90 80.00
d6 0.663 18.108 30.868
d13 19.716 7.656 0.300
d21 2.049 5.126 5.515
d24 2.806 9.044 13.166
d26 4.622 4.488 2.675
(Table 3)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
12 0.000 -0.7761E-03 0.6082E-05
13 0.000 -0.8760E-03 0.7967E-05
15 -0.306 -0.1859E-03 -0.5370E-06
16 0.000 0.3404E-03 -0.1387E-05
25 0.000 0.1149E-03 0.1459E-05 -0.8409E-07
26 0.000 0.4159E-03 -0.3890E-05
(Table 4)
Lens group data group Start surface Focal length
1 1 43.33
2 7 -5.87
3 15 8.78
4 22 -9.22
5 25 14.35

[Numerical Example 2]
5 to 8 and Tables 5 to 8 show Numerical Example 2 of the zoom lens system according to the present invention. FIG. 5 is a lens configuration diagram at the time of focusing at infinity at the short focal length end. FIGS. 6, 7 and 8 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 5 shows surface data, Table 6 shows various data, Table 7 shows aspherical data, and Table 8 shows lens group data.

The lens configuration of Numerical Example 2 is the same as that of Numerical Example 1 except for the following points.
(1) The negative lens 21 of the second lens group G2 is a plano-concave negative lens concave on the image side.
(2) The fourth lens group G4 is composed of a cemented lens made up of a biconvex positive lens 41 ′ and a biconcave negative lens 42 ′ that are positioned in this order from the object side.

(Table 5)
Surface data surface number rd N (d) νd
1 59.076 0.800 1.80450 39.6
2 22.148 0.461
3 22.853 3.739 1.43700 95.1
4 -277.967 0.100
5 23.625 3.171 1.59349 67.0
6 1493.450 d6
7 ∞ 0.700 1.91082 35.2
8 7.040 1.411
9 15.045 2.891 1.92286 20.9
10 -9.589 0.600 1.83481 42.7
11 11.438 1.379
12 * -18.108 0.700 1.83441 37.3
13 * -69.696 d13
14 stop ∞ 0.200
15 * 7.510 2.461 1.61881 63.8
16 * -21.097 0.100
17 19.573 1.400 1.51742 52.2
18 28.793 0.698 1.80518 25.5
19 7.095 0.238
20 10.133 1.645 1.48749 70.4
21 -9.601 d21
22 2411.767 1.133 1.72825 28.3
23 -9.301 0.500 1.83481 42.7
24 7.217 d24
25 * 42.749 2.234 1.53110 55.9
26 * -9.380 d26
27 ∞ 0.800 1.51680 64.2
28 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 6)
Various data zoom ratio (magnification ratio) 28.28
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 5.1 6.7
f 4.61 24.06 130.38
W 41.3 9.1 1.7
Y 3.44 3.96 3.96
fB 1.00 1.00 1.00
L 56.01 70.24 80.00
d6 0.531 17.888 30.146
d13 17.745 6.423 0.300
d21 2.000 5.120 5.867
d24 2.906 7.931 12.657
d26 4.470 4.524 2.672
(Table 7)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
12 0.000 -0.1715E-02 -0.6312E-05
13 0.000 -0.1740E-02 0.9494E-05
15 -0.346 -0.1346E-03 0.8669E-05
16 0.000 0.5450E-03 0.7140E-05
25 0.000 0.5019E-03 -0.1165E-04 0.4717E-06
26 0.000 0.7889E-03 -0.2118E-04 0.6746E-06
(Table 8)
Lens group data group Start surface Focal length
1 1 42.78
2 7 -5.31
3 15 8.22
4 22 -7.86
5 25 14.70

[Numerical Example 3]
9 to 12 and Tables 9 to 12 show Numerical Example 3 of the zoom lens system according to the present invention. FIG. 9 is a lens configuration diagram when focusing on infinity at the short focal length end. FIGS. 10, 11 and 12 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 9 shows surface data, Table 10 shows various data, Table 11 shows aspherical data, and Table 12 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 12 of the first lens group G1 is a positive meniscus lens convex toward the object side.
(2) The negative lens 21 of the second lens group G2 is a plano-concave negative lens concave on the image side.
(3) In the third lens group G3, the positive lens 32 is a biconvex positive lens, and the negative lens 33 is a biconcave negative lens.
(4) The fourth lens group G4 is composed of a cemented lens made up of a positive meniscus lens 41 ′ convex to the image side and a biconcave negative lens 42 ′ that are located in this order from the object side. The positive meniscus lens 41 ′ has an aspheric surface on the object side.

(Table 9)
Surface data surface number rd N (d) νd
1 49.567 0.800 1.80450 39.6
2 20.089 0.316
3 20.603 3.886 1.43700 95.1
4 1692.361 0.100
5 22.130 3.333 1.59349 67.0
6 1264.196 d6
7 ∞ 0.700 1.91082 35.2
8 6.690 1.317
9 11.464 3.012 1.92286 20.9
10 -11.395 0.600 1.83481 42.7
11 9.325 1.476
12 * -18.622 0.800 1.83441 37.3
13 * -136.070 d13
14 stop ∞ 0.200
15 * 8.058 2.500 1.61881 63.8
16 * -14.315 0.100
17 22.224 1.500 1.48749 70.4
18 -25.701 0.700 1.90366 31.3
19 10.895 0.214
20 20.575 1.618 1.56384 60.8
21 -7.505 d21
22 * -59.496 1.316 1.68893 31.2
23 -8.037 0.600 1.83481 42.7
24 7.303 d24
25 * 49.045 2.469 1.53110 55.9
26 * -8.143 d26
27 ∞ 0.800 1.51680 64.2
28 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 10)
Various data zoom ratio (magnification ratio) 28.28
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 5.2 6.7
f 4.61 24.44 130.39
W 41.4 9.0 1.7
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 55.88 71.43 80.00
d6 0.537 17.444 28.750
d13 16.810 6.461 0.300
d21 2.083 4.585 5.897
d24 2.901 9.450 13.025
d26 4.194 4.131 2.670
(Table 11)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
12 0.000 -0.1518E-02 -0.3749E-05
13 0.000 -0.1594E-02 0.1012E-04
15 -0.327 -0.1422E-03 0.1549E-04
16 0.000 0.8048E-03 0.1575E-04
22 0.000 0.1404E-03 0.5786E-06
25 0.000 0.2820E-03 -0.9404E-05 0.4764E-06
26 0.000 0.8069E-03 -0.2000E-04 0.7116E-06
(Table 12)
Lens group data group Start surface Focal length
1 1 41.70
2 7 -5.00
3 15 7.83
4 22 -6.83
5 25 13.35

[Numerical Example 4]
FIGS. 13 to 16 and Tables 13 to 16 show Numerical Example 4 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. FIGS. 14, 15 and 16 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 13 shows surface data, Table 14 shows various data, Table 15 shows aspheric data, and Table 16 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 is a planoconvex positive lens that is convex on the object side.
(2) In the third lens group G3, the positive lens 32 is a biconvex positive lens, and the negative lens 33 is a biconcave negative lens.
(3) The fourth lens group G4 is composed of a cemented lens made up of a biconvex positive lens 41 ′ and a biconcave negative lens 42 ′ that are positioned in this order from the object side.

(Table 13)
Surface data surface number rd N (d) νd
1 44.079 0.800 1.78590 43.9
2 20.409 0.300
3 20.717 4.221 1.43700 95.1
4 -652.967 0.100
5 21.696 3.435 1.49700 81.6
6 ∞ d6
7 -115.557 0.700 1.91082 35.2
8 6.093 1.437
9 12.228 3.304 1.84666 23.8
10 -7.143 0.600 1.83481 42.7
11 11.557 1.092
12 * -25.586 0.800 1.83441 37.3
13 * -43.359 d13
14 stop ∞ 0.200
15 * 8.260 1.973 1.61881 63.8
16 * -10.565 0.100
17 46.895 1.800 1.49700 81.6
18 -19.361 0.700 1.90366 31.3
19 13.775 0.285
20 301.235 1.527 1.51680 64.2
21 -6.551 d21
22 68.653 1.299 1.67270 32.2
23 -10.508 0.600 1.83481 42.7
24 5.999 d24
25 * 92.192 2.466 1.53110 55.9
26 * -7.978 d26
27 ∞ 0.800 1.51680 64.2
28 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 14)
Various data zoom ratio (magnification ratio) 28.27
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 5.3 6.7
f 4.61 23.90 130.38
W 40.5 9.1 1.8
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 56.89 69.65 80.00
d6 0.654 16.145 28.435
d13 18.000 6.329 0.300
d21 2.000 4.478 4.683
d24 2.989 9.255 14.371
d26 3.707 3.906 2.674
(Table 15)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
12 0.000 -0.2165E-03 -0.2485E-04
13 0.000 -0.5233E-03 -0.2385E-04 0.1982E-07
15 -0.856 -0.2184E-03 0.5595E-05
16 0.000 0.7832E-03 0.2659E-05
25 0.000 0.6259E-03 -0.6670E-05 0.1977E-06
26 0.000 0.1084E-02 -0.1472E-04 0.3654E-06
(Table 16)
Lens group data group Start surface Focal length
1 1 41.38
2 7 -5.28
3 15 8.03
4 22 -6.95
5 25 13.94

[Numerical Example 5]
17 to 20 and Tables 17 to 20 show Numerical Example 5 of the zoom lens system according to the present invention. FIG. 17 is a lens configuration diagram when focusing on infinity at the short focal length end. 18, 19 and 20 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 17 shows surface data, Table 18 shows various data, Table 19 shows aspherical data, and Table 20 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 positive lens 12 of the first lens group G1 is a positive meniscus lens convex toward the object side.
(2) The second lens group G2 includes, in order from the object side, a negative meniscus lens 21 ′ that is convex on the object side, a biconcave negative lens 22 ′, a biconvex positive lens 23 ′, and a negative meniscus lens 24 ′ that is convex on the image side. Consists of. The biconvex positive lens 23 'has an aspheric object side surface.
(3) The fourth lens group G4 is convex from the object side, a cemented lens of a positive meniscus lens 41 ″ convex to the image side and a biconcave negative lens 42 ″, and convex from the object side. It consists of a positive meniscus lens 43 ″. The positive meniscus lens 41 ″ has an aspheric surface on the object side, and the positive meniscus lens 43 ″ has an aspheric surface on the image side.

(Table 17)
Surface data surface number rd N (d) νd
1 38.117 0.800 1.78590 43.9
2 20.168 0.109
3 20.028 4.288 1.43700 95.1
4 238.727 0.100
5 23.708 3.505 1.49700 81.6
6 896.740 d6
7 102.467 0.700 1.83481 42.7
8 6.018 2.665
9 -21.087 0.600 1.83481 42.7
10 25.128 0.100
11 * 13.987 2.500 1.82115 24.1
12 -13.216 0.400
13 -8.878 0.600 1.77250 49.6
14 -126.046 d14
15 stop ∞ 0.000
16 * 7.896 1.954 1.69680 55.5
17 * -24.991 0.486
18 10.740 1.431 1.49700 81.6
19 720.006 0.700 1.90366 31.3
20 6.230 0.314
21 10.695 1.641 1.48749 70.4
22 -11.532 d22
23 * -14.776 1.135 1.68893 31.2
24 -8.203 0.600 1.83481 42.7
25 13.190 0.215
26 34.068 1.000 1.82115 24.1
27 * 76.852 d27
28 * 18.494 2.883 1.53110 55.9
29 * -10.655 d29
30 ∞ 0.800 1.51680 64.2
31 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 18)
Various data zoom ratio (magnification ratio) 28.28
Short focal length end Intermediate focal length Long focal length end
FNO. 3.1 5.0 6.7
f 4.61 24.45 130.39
W 40.3 9.0 1.7
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 60.76 75.54 87.00
d6 0.559 19.070 31.272
d14 20.831 8.345 1.942
d22 2.184 5.475 6.008
d27 2.614 8.324 14.579
d29 4.033 3.803 2.672
(Table 19)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
11 -0.197 0.1709E-03 -0.2553E-05 0.1355E-06
16 -0.708 -0.1058E-05 0.1553E-05
17 0.000 0.2932E-03 -0.1032E-05
23 0.000 0.9467E-03 -0.3858E-05
27 0.000 0.6652E-03 0.8136E-05
28 0.000 0.1833E-03 -0.2013E-05 -0.5037E-07
29 0.000 0.6035E-03 -0.1183E-04 0.7917E-07
(Table 20)
Lens group data group Start surface Focal length
1 1 45.59
2 7 -5.62
3 16 9.07
4 23 -8.50
5 28 13.18

[Numerical Example 6]
21 to 24 and Tables 21 to 24 show Numerical Example 6 of the zoom lens system according to the present invention. FIG. 21 is a lens configuration diagram at the time of focusing on infinity at the short focal length end. FIGS. 22, 23, and 24 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 21 shows surface data, Table 22 shows various data, Table 23 shows aspherical data, and Table 24 shows lens group data.

The lens configuration of Numerical Example 6 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 12 is a positive meniscus lens convex toward the object side, and the positive lens 13 is a biconvex positive lens.
(2) The second lens group G2 includes, in order from the object side, a plano-concave negative lens 21 ′ concave to the image side, a biconcave negative lens 22 ′, a biconvex positive lens 23 ′, and a negative meniscus lens convex to the image side 24 '. The biconvex positive lens 23 'has an aspheric object side surface.
(3) In the third lens group G3, the positive lens 32 is a biconvex positive lens, and the negative lens 33 is a biconcave negative lens.
(4) The fourth lens group G4 includes a biconcave negative single lens 41 ′ ″.

(Table 21)
Surface data surface number rd N (d) νd
1 42.097 1.210 1.78590 43.9
2 21.462 0.330
3 21.614 4.235 1.43700 95.1
4 714.083 0.100
5 24.663 3.220 1.49700 81.6
6 -7948.963 d6
7 ∞ 0.700 1.88300 40.8
8 6.222 2.639
9 -22.452 0.600 1.83481 42.7
10 18.645 0.100
11 * 15.660 2.531 1.82115 24.1
12 -12.858 0.245
13 -10.335 1.200 1.77250 49.6
14 -29.609 d14
15 stop ∞ 0.000
16 * 6.693 2.102 1.62263 58.2
17 * -24.793 0.206
18 12.248 1.562 1.49700 81.6
19 -16.462 0.700 1.83400 37.3
20 5.501 0.249
21 7.663 1.680 1.48749 70.4
22 -16.439 d22
23 -21.160 0.600 1.51742 52.2
24 10.119 d24
25 * 14.090 2.936 1.53110 55.9
26 * -13.466 d26
27 ∞ 0.800 1.51680 64.2
28 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 22)
Various data zoom ratio (magnification ratio) 28.27
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 5.1 6.4
f 4.61 24.45 130.35
W 40.1 8.9 1.7
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 59.95 74.09 87.00
d6 0.573 19.429 33.505
d14 19.884 6.397 0.500
d22 2.194 8.382 2.386
d24 2.896 6.459 18.909
d26 5.460 4.477 2.757
(Table 23)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
11 4.454 0.6009E-04 -0.3712E-05
16 -0.875 0.1855E-03 0.3385E-05
17 0.000 0.2539E-03 -0.5342E-06
25 0.000 0.2548E-03 -0.8626E-05 0.2552E-06
26 0.000 0.5536E-03 -0.1252E-04 0.2804E-06
(Table 24)
Lens group data group Start surface Focal length
1 1 45.65
2 7 -6.58
3 16 10.61
4 23 -13.14
5 25 13.46

[Numerical Example 7]
25 to 28 and Tables 25 to 28 show Numerical Example 7 of the zoom lens system according to the present invention. FIG. 25 is a lens configuration diagram at the time of focusing on infinity at the short focal length end. FIGS. 26, 27, and 28 are graphs showing various aberrations at the time of focusing at infinity at the short focal length end, the intermediate focal length, and the long focal length end, respectively. Table 25 shows surface data, Table 26 shows various data, Table 27 shows aspherical data, and Table 28 shows lens group data.

The lens configuration of Numerical Example 7 is the same as the lens configuration of Numerical Example 1 except for the following points.
(1) The negative meniscus lens 11 and the biconvex positive lens 12 of the first lens group G1 are cemented.
(2) The second lens group G2 includes, in order from the object side, a negative meniscus lens 21 ′ convex to the object side, a biconcave negative lens 22 ′, a biconvex positive lens 23 ′, and a plano-concave negative lens concave on the object side. 24 '. The biconvex positive lens 23 'has an aspheric object side surface.
(3) The third lens group G3 includes, in order from the object side, a biconvex positive lens 31 ′, a negative meniscus lens 32 ′ convex to the object side, and a biconvex positive lens 33 ′. The biconvex positive lens 31 ′ has two aspheric surfaces.
(4) The fourth lens group G4 includes a biconcave negative single lens 41 ′ ″.

(Table 25)
Surface data surface number rd N (d) νd
1 54.638 1.200 1.78590 43.9
2 25.673 4.856 1.43700 95.1
3 -353.673 0.100
4 26.206 3.151 1.49700 81.6
5 381.350 d5
6 228.352 0.700 1.88300 40.8
7 7.214 2.741
8 -23.403 0.600 1.83481 42.7
9 23.403 0.100
10 * 14.248 2.708 1.82115 24.1
11 -12.744 0.238
12 -10.262 0.600 1.77250 49.6
13 ∞ d13
14 stop ∞ 0.000
15 * 7.928 1.819 1.62263 58.2
16 * -39.265 0.880
17 20.729 1.400 1.84666 23.8
18 7.270 0.193
19 9.881 1.841 1.49700 81.6
20 -9.881 d20
21 -37.367 0.746 1.62041 60.3
22 7.709 d22
23 * 21.452 2.460 1.53110 55.9
24 * -12.542 d24
25 ∞ 0.800 1.51680 64.2
26 ∞-
* Is a rotationally symmetric aspherical surface.
(Table 26)
Various data zoom ratio (magnification ratio) 28.27
Short focal length end Intermediate focal length Long focal length end
FNO. 3.2 4.7 6.1
f 4.61 24.46 130.38
W 40.8 8.9 1.7
Y 3.45 3.96 3.96
fB 1.00 1.00 1.00
L 59.49 72.97 87.00
d5 0.638 21.581 37.819
d13 20.000 5.406 0.500
d20 2.104 6.159 2.432
d22 3.145 6.672 15.410
d24 5.474 5.019 2.708
(Table 27)
Aspheric data (Aspherical coefficient not shown is 0.00)
Surface number K A4 A6 A8
10 3.823 -0.9055E-04 -0.4230E-05
15 -2.819 0.6010E-03 -0.2300E-05
16 0.000 0.4579E-03 0.2199E-07
23 0.000 0.2263E-03 -0.1590E-05 0.1108E-06
24 0.000 0.3977E-03 -0.6358E-05 0.1746E-06
(Table 28)
Lens group data group Start surface Focal length
1 1 50.93
2 6 -6.58
3 15 9.12
4 21 -10.24
5 23 15.29

Table 29 shows values for the conditional expressions of the numerical examples.
(Table 29)
Example 1 Example 2 Example 3 Example 4
Conditional expression (1) 0.149 0.134 0.127 0.136
Conditional expression (2) 3.009 3.048 3.126 3.151
Conditional expression (3) 95.100 95.100 95.100 95.100
Conditional expression (4) 39.640 39.640 39.640 43.930
Conditional expression (5) 8.868 8.228 7.831 8.168
Conditional expression (6) -0.725 -0.790 -0.756 -0.914
Conditional expression (7) 9.084 8.868 9.768 9.350
Example 5 Example 6 Example 7
Conditional expression (1) 0.145 0.149 0.150
Conditional expression (2) 2.860 2.855 2.560
Conditional expression (3) 95.100 95.100 95.100
Conditional expression (4) 43.930 43.930 43.930
Conditional expression (5) 8.113 14.414 14.887
Conditional expression (6) -0.651 -0.735 -0.767
Conditional expression (7) 9.892 9.683 8.529

  As apparent from Table 29, Numerical Example 1 to Numerical Example 7 satisfy the conditional expressions (1) to (7), and various aberrations are corrected relatively well as is apparent from the various aberration diagrams. ing.

G1 First lens group 11 with positive refractive power 11 Negative lens 12 Positive lens 13 Positive lens G2 Second lens group 21 with negative refractive power Negative lens 22 Positive lens 23 Negative lens 24 Negative lens 21 'Negative lens 22' Negative lens 23 'Positive lens 24' Negative lens G3 Third lens group 31 with positive refractive power Positive lens 32 Positive lens 33 Negative lens 34 Positive lens 31 'Positive lens 32' Negative lens 33 'Positive lens G4 Fourth lens with negative refractive power Group 41 negative lens 42 positive lens 41 ′ positive lens 42 ′ negative lens 41 ″ positive lens 42 ″ negative lens 43 ″ positive lens 41 ′ ″ negative lens G5 fifth lens group 51 with positive refractive power 51 positive single lens S Aperture OP Optical filter I Image plane

Claims (10)

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, a fourth lens group having a negative refractive power, and 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 increases during zooming from the short focal length end to the long focal length end. In the decreasing zoom lens system,
A zoom lens system satisfying the following conditional expressions (1) and (2):
(1) 0.10 <| d23t−d23w | / ft <0.20
(2) 2.50 <ft / f1 <5.00
However,
d23t: the air space between the second lens group and the third lens group at the long focal length end,
d23w: the air space between the second lens group and the third lens group at the short focal length end,
ft: focal length of the entire system at the long focal length end,
f1: Focal length of the first lens group. 2. The zoom lens system according to claim 1, wherein the first lens group includes three lenses of a negative lens, a positive lens, and a positive lens in order from the object side, and satisfies the following conditional expressions (3) and (4): Zoom lens system.
(3) LPνd> 95
(4) LNνd> 39
However,
LPνd: Abbe number of the positive lens on the object side in the first lens group with respect to the d-line,
LNνd: Abbe number for the d-line of the negative lens in the first lens group. The zoom lens system according to claim 1 or 2, wherein the zoom lens system satisfies the following conditional expression (5).
(5) 7.5 <m2t / m2w <15.0
However,
m2t: lateral magnification of the second lens group at the time of focusing at infinity at the long focal length end,
m2w: lateral magnification of the second lens group at the time of focusing at infinity at the short focal length end. 4. The zoom lens system according to claim 1, wherein the second lens group includes a negative lens in order from the object side, a cemented lens of a positive lens and a negative lens positioned in order from the object side, and a negative lens. A zoom lens system comprising four lenses, wherein at least one lens has an aspherical surface. 4. The zoom lens system according to claim 1, wherein the second lens group includes four lenses of a negative lens, a negative lens, a positive lens, and a negative lens in order from the object side. Zoom lens system in which the lens has an aspherical surface. 6. The zoom lens system according to claim 4, wherein the zoom lens system satisfies the following conditional expression (6).
(6) -0.92 <f2p / f2 <-0.65
However,
f2p: the focal length of the positive lens in the second lens group,
f2: Focal length of the second lens group. 7. The zoom lens system according to claim 1, wherein the fifth lens group forms a focus lens group that moves during focusing and satisfies the following conditional expression (7).
(7) 8.5 <ft / f5 <20.0
However,
ft: focal length of the entire system at the long focal length end,
f5: focal length of the fifth lens group. 8. The zoom lens system according to claim 1, wherein a focus lens group in which both the fourth lens group and the fifth lens group move during focusing in at least a part of a zooming region. . 9. The zoom lens system according to claim 1, wherein the third lens group includes, in order from the object side, a positive lens, a cemented lens of a positive lens and a negative lens positioned in order from the object side, and a positive lens. A zoom lens system composed of four lenses or three lenses of a positive lens, a negative lens and a positive lens in order from the object side. 10. The zoom lens system according to claim 1, wherein the fourth lens group includes a negative single lens, a cemented lens of a negative lens and a positive lens positioned in order from the object side, and a positive lens positioned in order from the object side. And a negative lens cemented lens, or a zoom lens system composed of three lenses, a positive lens and a negative lens cemented in this order from the object side, and a positive lens.

Images