KR20130122868A - Zoom lens system and photographing apparatus - Google Patents

Abstract

The present invention relates to a zoom lens system and a photographing device having the same. The zoom lens system comprises: a first lens group which has positive refractive power; a second lens group which has negative refractive power and comprises positive and negative lenses; a third lens group which has positive refractive power; and a forth lens group which has positive refractive power and comprises a positive lens. The zoom lens system performs zooming by changing the intervals among the first, second, third, and forth lens groups.

Description

Zoom lens system and photographing apparatus having same {Zoom lens system and photographing apparatus}

The present invention relates to a zoom lens system, and more particularly to a four-group zoom lens system and a photographing apparatus having the same.

The storage capacity of a photographing device that implements an image using a CCD or CMOS has been increasing as it is converted to digital. As the storage capacity increases, the demand for miniaturization for the convenience of the optical system and the convenience of the lens system employed in the digital photographing apparatus has gradually increased.

The lens system should be well corrected to aberrations generated around the screen in order to clearly record even small information of the subject, and high magnification should be implemented to acquire various images. However, in order to realize high performance, it is difficult to achieve miniaturization, and in order to miniaturize, it is difficult to satisfy both high optical performance and manufacturing cost as the manufacturing cost is increased.

Japanese Patent Laid-Open No. 2011-227240 (2009.05.26) "Zoom lens and optical device having the same

One embodiment of the present invention relates to a four-group zoom lens system and a photographing apparatus having the same.

According to an aspect of the present invention, there is provided a zoom lens comprising, in order from an object side to an image side, a first lens group having positive refractive power; A second lens group having negative refractive power and comprising a negative lens and a positive lens; A third lens group having positive refractive power; And a fourth lens group having a positive refractive power and including a positive lens, and zooming by changing a distance between the first to fourth lens groups, and satisfying the following equation. have.

<Expression>

Here, Nd ₅ represents a refractive index of the negative lens of the second lens group, Nd ₆ represents a refractive index of the positive lens of the second lens group, and Nd ₉ represents a refractive index of the positive lens of the fourth lens group. .

According to one feature of the invention, the negative lens and the positive lens of the second lens group may constitute a junction lens.

According to another feature of the invention, the second lens group may further include a negative lens disposed on the object side of the negative lens.

According to another feature of the invention, the fourth lens group further comprises a negative lens disposed on the image side of the positive lens, the positive lens and the negative lens of the fourth lens group may constitute a junction lens. Can be.

According to another feature of the invention, the fourth lens group may include at least one aspherical surface.

According to another feature of the invention, the zoom lens system may satisfy the following equation.

<Expression>

Here, F _T is the total focal length at the telephoto end of the zoom lens system, and F _W is the total focal length at the wide-angle end of the zoom lens system.

According to another feature of the invention, the zoom lens system may satisfy the following equation.

<Expression>

Fno _{_t} ≤1.9

Here, Fno represents the F-number is _{_t} at the telephoto end.

According to another feature of the invention, the zoom lens system may satisfy the following equation.

<Expression>

9.5% ≤ BFL / OAL

Here, BFL represents a back focal length of the zoom lens system, and OAL represents a distance from the center of the object-side surface of the most object-side lens of the first lens group to the image plane.

According to another feature of the present invention, the back focal length BFL of the zoom lens system may satisfy the following equation.

<Expression>

BFL ≥ 6.4

According to another feature of the present invention, when zooming from the wide end to the telephoto end, the second lens group and the fourth lens group are moved, and the first lens group and the third lens group are fixed. Can be.

According to another feature of the present invention, the distance from the center of the object-side surface of the first lens group to the image plane (OAL) may satisfy the following equation.

<Expression>

 51.5 ≤ OAL ≤ 53.5

According to another aspect of the invention, the zoom lens system as described above; And an imaging sensor for changing an image formed by the zoom lens system into an electrical signal.

According to one embodiment of the present invention as described above, by providing a zoom lens system having an aspherical lens and a high refractive lens and satisfying various conditions therebetween, high magnification and high resolution can be realized while miniaturization. In addition, since a sufficient rear focal length is ensured so that filters used at night and daytime can be switched and arranged, a high performance imaging device can be provided.

1 is a perspective view schematically showing a zoom lens system according to an embodiment of the present invention.
FIG. 2 is a longitudinal aberration diagram at the wide-angle end of the zoom lens system of FIG. 1.
3 is a horizontal aberration diagram at a wide-angle end of the zoom lens system of FIG. 1.
4 is a perspective view schematically showing a zoom lens system according to another embodiment of the present invention.
5 is a longitudinal aberration diagram at the wide-angle end of the zoom lens system of FIG.
FIG. 6 is a horizontal aberration diagram at the wide-angle end of the zoom lens system of FIG. 4.
7 is a perspective view schematically showing a zoom lens system according to another embodiment of the present invention.
8 is a longitudinal aberration diagram at the wide-angle end of the zoom lens system of FIG.
FIG. 9 is a horizontal aberration diagram at the wide-angle end of the zoom lens system of FIG. 7.
FIG. 10 schematically illustrates a photographing apparatus having a zoom lens system according to an exemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

1, 4, and 7 illustrate a zoom lens system according to an exemplary embodiment of the present invention.

1, 4, and 7, the zoom lens system according to the exemplary embodiment of the present invention includes the first lens group G1 and the second lens group G2 in the order from the object O to the image I side. ), The third lens group G3, and the fourth lens group G4. An aperture ST may be provided between the second lens group G2 and the third lens group G3.

The first lens group G1 has a positive refractive power. The first lens group G1 may include three lenses. For example, the first lens group G1 has positive refractive power and has a positive refractive power of the first lens 11, 11 ′, 11 ″ having a meniscus shape in which the convex surface faces the object side, and the second convex second lens. 12, 12 ′, 12 ″, and third lenses 13, 13 ′, 13 ″ having positive refractive power.

The second lens group G2 has negative refractive power. The second lens group G2 may include three lenses. For example, the second lens group G2 includes the fourth lenses 21, 21 ′, 21 ″ having negative refractive power, and the fifth lenses 22, 22 ′, 22 ″ having negative refractive power and the sixth lens having positive refractive power. (23, 23 ', 23 "), and the fifth lens (22, 22', 22") and the sixth lens constitute a bonded lens, it is possible to effectively correct magnification chromatic aberration.

The fifth lenses 22, 22 ′, 22 ″ and the sixth lenses 23, 23 ′, 23 ″ may satisfy the condition of Equation 1 below.

………(식 1)

... ... ... (Equation 1)

Here, Nd ₅ represents the refractive index of the fifth lens 22, 22 ′, 22 ″, and Nd ₆ represents the refractive index of the sixth lens 23, 23 ′, 23 ″.

Equation 1 defines the ratio of the refractive indices of the fifth lenses 22, 22 'and 22 "to the refractive indices of the sixth lenses 23, 23' and 23". If this value is smaller than the lower limit, the image surface curvature increases. If it is larger than the upper limit, the distortion is increased.

The third lens group G3 has a positive refractive power. For example, the third lens group G3 may include a seventh lens 31, 31 ′, 31 ″ having positive refractive power, and a seventh lens 32, 32 ′, 32 ″ having negative refractive power. . The third lens group G3 may include at least one aspherical surface. For example, the seventh lens 31, 31 ′, 31 ″ may include an aspherical surface.

The fourth lens group G4 has a positive refractive power. For example, the fourth lens group G4 may include a ninth lens 41, 41 ′, 41 ″ having positive refractive power, and a tenth lens 42, 42 ′, 42 ″ having negative refractive power. The ninth lens 41, 41 ′, 41 ″ and the tenth lens 42, 42 ′, 42 ″ may form a cemented lens to effectively correct magnification chromatic aberration.

The ninth lenses 41, 41 ', and 41 "may satisfy the following expression (2).

………(식 2)

... ... ... (Equation 2)

Here, Nd ₉ represents the refractive indices of the ninth lenses 41, 41 ', 41 ".

Equation 2 defines the refractive index of the ninth lens. If this value is larger than the upper limit, it is difficult to control coma aberration, and as described later, sufficient space for switching the filter, such as a rear focal length, cannot be secured .

The fourth lens group G4 may include at least one aspherical surface to effectively remove astigmatism generated during zooming. For example, at least one of the object side surface and the image side surface of the ninth lens 41, 41 ′, 41 ″ may include an aspherical surface.

The zoom lens system according to the exemplary embodiments of the present invention may zoom in by changing an interval between the first to fourth lens groups G1 to G4. The zoom lens system includes the second lens group G2 and the third lens group G3 including a lens having a relatively high refractive power of about 1.8 or more, thereby satisfying Equation 3 below.

………(식 3)

... ... ... (Equation 3)

Here, F _T denotes the total focal length at the telephoto end of the zoom lens system, and F _W denotes the total focal length at the wide-angle end of the zoom lens system. Embodiments of the present invention can provide a high magnification zoom lens system of 11.85 to 13.85 times.

When zooming from the wide end to the telephoto end, the second lens group G2 and the fourth lens group G4 move, and the first lens group G1 and the third lens group G3 are fixed without moving. Can be. The distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3 decreases, and the third lens group G3 ) And the fourth lens group G4 may decrease and then increase. In zooming, the second lens group G2 is responsible for the magnification. For example, the second lens group G2 may implement a magnification from the wide-angle end to the telephoto end while moving from the object side to the image side.

Since the first lens group G1 does not move during zooming, the distance from the center of the object-side surface of the first lens group G1 to the image plane IP, that is, the overall length OAL of the zoom lens system does not change. Can implement a zoom lens system. For example, the overall length of a zoom lens system is about 51.5 ≤ OAL ≤ 53.5 Lt; / RTI &gt;

Meanwhile, the zoom lens system according to the embodiment of the present invention may satisfy Equation 4 below.

9.5% ≦ BFL / OAL... ... ... (Equation 4)

Here, BFL represents a back focal length of the zoom lens system, and OAL represents a distance from the center of the object-side surface of the most object-side lens of the first lens group to the image plane IP.

Equation 4 defines the rear focal length with respect to the over-all length (OAL) of the zoom lens system, and embodiments of the present invention can provide a rear focal length of about 9.5% or more with respect to the entire full length.

In the case of a photographing device such as a surveillance camera (CCTV), it is necessary to take an image at night as well as during the day. Surveillance cameras should be provided with respective filters suitable for daytime shooting and nighttime shooting in order to obtain a high quality image, wherein the daytime filter and the nighttime filter may be switched by a switching device (not shown). That is, in the zoom lens system, a space in which a filter may be provided and a space that can be switched should be sufficiently secured. Since the zoom lens system according to the exemplary embodiment of the present invention has a rear focal length of about 9.5% or more with respect to the entire length, it is easy to switch and arrange the filter. More specifically, the rear focal length may be about 6.4 mm. In this way, a rear focal length sufficient to switch at the same time as the filter is placed can be ensured by using a low refractive power ninth lens of less than about 1.51 as shown in Equation 2 above.

The zoom lens system according to the embodiment of the present invention may satisfy the following equations.

Fno _{t t} 1.9. ... ... (Equation 5)

Here, Fno_ _t represents the F-number at the telephoto end. Embodiments of the present invention can provide a bright zoom lens system having an F number of about 1.9 or less in the telephoto end.

The following shows the design data of the zoom lens system according to the embodiment of the present invention.

Hereinafter, F represents a focal length, Fno represents an F number, and variable1 to 4 represent variable distances. variable1 is the distance between the first lens group G1 and the second lens group G2, variable2 is the distance between the second lens group G2 and the aperture ST, and variable3 is the third lens group G3. And the distance between the fourth lens group G4 and variable4 represent the distance between the fourth lens group G4 and the filter F1. Ri represents the curvature radius of the lens or optical member, Dj represents the lens center thickness, the optical member thickness or the distance between the lens and the lens, nd represents the refractive index of the material, and vd represents the Abbe number of the material.

The definitions of aspherical surfaces in the embodiment of the present invention are as follows.

The aspheric surface shape of the zoom lens according to the embodiment of the present invention can be expressed by the following expression with the direction of the light ray as a positive when the direction of the optical axis is the x axis and the direction perpendicular to the optical axis direction is the y axis have. Where x is the distance from the vertex of the lens to the optical axis direction, y is the distance in the direction perpendicular to the optical axis, k is a conic constant, A, B, C and D are aspheric coefficients, and c represents the inverse number (1 / R) of the radius of curvature at the apex of the lens.

&Lt; Embodiment 1 >

Table 1 shows design data of the zoom lens system according to the exemplary embodiment shown in FIG. 1. In addition, an optical member such as filters F1 and F2 may be further provided between the fourth lens group G4 and the image plane IP in FIG. 1.

F: 3.87-46.10

Fno .: 1.69 ~ 1.89

Surface Ri Dj nd vd One: 41.84282 1.000000 1.922860 20.8804   2: 24.62711 4.965308 1.496997 81.6084   3: -83.79034 0.200000   4: 19.62419 3.605970 1.796098 46.5473   5: 51.77687 variable1   6: 38.26908 0.500000 1.841590 39.8970   7: 6.34530 2.387661   8: -9.33287 0.500000 1.800619 46.4052   9: 7.04405 2.725942 1.846663 23.7848  10: -52.92336 variable2  11 (ST) INFINITY 0.200000  12: 5.37186 2.695990 1.609829 55.7869  13: 30.04631 1.103363  14: 8.51615 0.500000 1.846663 23.7848  15: 4.93248 variable3  16: 7.55288 2.017072 1.497103 81.5596  17: -5.16259 0.491722 1.614816 37.9292  18: -10.63109 variable4  19: INFINITY 2.120000 1.516798 64.1983  20: INFINITY 0.300000  21: INFINITY 0.500000 1.516798 64.1983  22: INFINITY 3.778810  IP: INFINITY

Table 2 shows aspherical surface coefficients in the zoom lens system shown in FIG.

Surface k A B C D 12 -0.577110 -.126697E-05 0.711775E-05 0.125020E-06 0.000000E + 00 13 -12.33973 .120066E-03 0.177619E-04 -.428400E-06 0.000000E + 00 16 -0.618125 -.539927E-03 0.337081E-04 -.265061E-05 0.000000E + 00

variable1 variable2 variable3 variable4 Wide angle 0.5173 17.6677 2.9801 2.2419 6.2092 11.9758 1.8509 3.3711 Middle 11.4650 6.7199 0.79 4.4320 14.1355 4.0494 1.4298 3.7922 Telephoto 16.3850 1.8 5.0220 0.2

FIG. 2 shows longitudinal spherical aberration, astigmatic field curves and distortion at the wide-angle end of the zoom lens system shown in FIG. The longitudinal spherical aberration is shown for light having wavelengths of about 656.28 nm, 587.56 nm, 546.07 nm, 486.13 nm, 435.84 nm, and the surface curvature and distortion are shown for light having a wavelength of about 546.07 nm.

3 illustrates coma aberration at the wide-angle end of the zoom lens system illustrated in FIG. 1.

&Lt; Embodiment 2 >

Table 4 shows design data of the zoom lens system according to the exemplary embodiment shown in FIG. 4. In addition, an optical member such as filters F1 and F2 may be further provided between the fourth lens group G4 and the image plane IP in FIG. 4.

F: 3.83-46.2

Fno .: 1.61 ~ 1.82

Surface Ri Dj nd vd One: 42.49272 0.500000 1.922860 20.8804     2: 25.77366 4.857664 1.496997 81.6084     3: -76.40037 0.200000     4: 19.71367 3.029047 1.753826 48.0071     5: 51.27753 variable1     6: 30.12254 0.500000 1.841590 39.8970     7: 7.54339 2.678234     8: -9.64683 0.500000 1.820020 45.8225     9: 6.21559 2.509893 1.846663 23.7848    10: 709.94015 variabel2    11 (st): INFINITY 0.200000    12: 5.71979 2.727058 1.609829 55.7869    13: 45.17218 0.969381    14: 8.07485 0.500000 1.846663 23.7848    15: 4.52398 variable3    16: 6.40994 2.538075 1.506455 67.4701    17: -6.92043 0.483221 1.766202 26.4529    18: -11.77728 variable4    19: INFINITY 2.120000 1.516798 64.1983    20: INFINITY 0.300000    21: INFINITY 0.500000 1.516798 64.1983    22: INFINITY 3.280025    IP: INFINITY

Table 5 shows aspherical coefficients in the zoom lens system shown in FIG. 4, and Table 6 shows variable distances at the wide-angle end, the intermediate end, and the telephoto end, respectively.

Surface k A B C D 12 -0.583052 -.634904E-04 0.912368E-06 0.380558E-06 -.350840E-08 13 -28.056094 328949E-04 0.990128E-05 0.307061E-06 -.153669E-07 16 -0.624686 -.531337E-03 0.330713E-04 -.246348E-05 0.000000E + 00

variable1 Variable2 Variable3 Variable4 Wide angle  0.5548 18.1077 2.9441 2.0009  6.4382 12.2243 1.7718 3.1732 Middle 11.7391  6.9234 0.6225 4.3225 14.4630  4.1995 1.1336 3.8113 Telephoto 16.8625 1.8 4.7450 0.2

FIG. 5 shows longitudinal spherical aberration, astigmatic field curves and distortion at the wide-angle end of the zoom lens system shown in FIG. The longitudinal spherical aberration is shown for light having wavelengths of about 656.28 nm, 587.56 nm, 546.07 nm, 486.13 nm, 435.84 nm, and the surface curvature and distortion are shown for light having a wavelength of about 546.07 nm.

6 illustrates coma aberration at the wide-angle end of the zoom lens system illustrated in FIG. 4.

&Lt; Third Embodiment >

Table 7 shows design data of the zoom lens system according to the exemplary embodiment illustrated in FIG. 7. In addition, an optical member such as filters F1 and F2 may be further provided between the fourth lens group G4 and the image plane IP in FIG. 7.

F: 3.83-46.2

Fno .: 1.67 ~ 1.89

Surface Ri Dj nd vd      One: 38.43167 1.000000 1.922860 20.8804      2: 23.87262 5.231165 1.496997 81.6084      3: -95.11061 0.200000      4: 19.74718 3.665687 1.753826 48.0071      5: 57.35380 variable1      6: 54.16806 0.500000 1.841590 39.8970      7: 7.59027 2.585316      8: -10.02427 0.500000 1.820020 45.8225      9: 6.38282 3.003814 1.846663 23.7848     10: -107.64266 variable2     11 (ST): INFINITY 0.200000     12: 4.90858 2.899730 1.609829 55.7869     13: 26.84852 0.564219     14: 7.14805 0.500000 1.846663 23.7848     15: 4.21781 variable3     16: 6.81548 1.880168 1.480000 72.4000     17: -5.53206 0.354133 1.657957 33.7255     18: -10.85062 variable4     19: INFINITY 2.120000 1.516798 64.1983     20: INFINITY 0.300000     21: INFINITY 0.500000 1.516798 64.1983     22: INFINITY 3.780007     IP: INFINITY

Table 8 shows aspherical coefficients in the zoom lens system shown in FIG. 7, and Table 9 shows variable distances at the wide-angle end, the intermediate end, and the telephoto end, respectively.

Surface k A B C D 12 -0.564510 -.318790E-04 0.139903E-05 0.450884E-06 -.134166E-07 13 -17.860490 0.427266E-04 0.154568E-04 -.432217E-06 -.598535E-08 16 -0.571798 -.527667E-03 0.400409E-04 -.275207E-05 0.000000E + 00

variable1 variable2 variable3 variable4 Wide angle 0.2 17.5622  3.3794 2.0742 5.9396 11.8226 2.1960 3.2576 Middle 11.1029  6.6594 1.0815 4.3720 13.7290 4.0332  1.6690 3.7845 Telephoto 15.9622 1.8  5.2536 0.2

FIG. 8 shows longitudinal spherical aberration, astigmatic field curves and distortion at the wide-angle end of the zoom lens system shown in FIG. The longitudinal spherical aberration is shown for light having wavelengths of about 656.28 nm, 587.56 nm, 546.07 nm, 486.13 nm, 435.84 nm, and the surface curvature and distortion are shown for light having a wavelength of about 546.07 nm.

9 illustrates coma aberration at the wide-angle end of the zoom lens system illustrated in FIG. 7.

Table 9 below shows that the first to third embodiments satisfy the above equations.

Equation 1 Equation 2 Equation 3 Equation 4 BFL OAL Equation 5 Example 1 0.974 1.497103 11.91 13 6.918 53 1.69-1.89 Example 2 0.985 1.506455 12.06 12.3 6.40 52 1.61-1.82 Example 3 0.985 1.480000 12.06 13 6.90 53 1.67-1.89

The zoom lens system as described above can be used in a photographing apparatus such as a surveillance camera using a solid state photographing element such as a CCD or a CMOS.

10 illustrates a photographing apparatus having a zoom lens system according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the photographing apparatus 1000 according to the present exemplary embodiment includes a zoom lens system 100 and an imaging sensor 200 that converts light focused by the zoom lens system 100 into an electrical image signal.

Information about the image of the photoelectrically converted subject from the imaging sensor 200 may be transmitted to an image processing apparatus (not shown) that is separately provided and output as an image to a user who uses the surveillance camera.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications and variations without departing from the spirit and scope of the invention. Accordingly, it is intended that the appended claims cover all such modifications and variations as fall within the true spirit of the invention.

11,11 ', 11 ": first lens 12,12', 12": second lens
13,13 ', 13 ": 3rd lens 21,21', 21": 4th lens
22, 22 ', 22 ": Fifth lens 23, 23', 23": Sixth lens
31, 31 ', 31 ": 7th lens 32, 32', 32": 8th lens
41,41 ', 41 ": 9th lens 42,42', 42": 10th lens
G1: first lens group G2: second lens group
G3: third lens group G4: fourth lens group
ST: Aperture 100: Zoom lens system
200: imaging sensor

Claims (12)

In order from the object side to the image side,
A first lens group having positive refractive power;
A second lens group having negative refractive power and comprising a negative lens and a positive lens;
A third lens group having positive refractive power; And
And a fourth lens group having positive refractive power and including a positive lens.
A zoom lens system that zooms by changing an interval between the first to fourth lens groups, and satisfies the following expression.
<Expression>

Here, Nd ₅ represents a refractive index of the negative lens of the second lens group, Nd ₆ represents a refractive index of the positive lens of the second lens group, and Nd ₉ represents a refractive index of the positive lens of the fourth lens group. . The method of claim 1,
And a negative lens and the positive lens of the second lens group constitute a bonded lens. 3. The method according to claim 1 or 2,
The second lens group further includes a negative lens disposed on an object side of the negative lens. The method of claim 1,
The fourth lens group further includes a negative lens disposed on the image side of the positive lens,
The zoom lens system of the fourth lens group, wherein the positive lens and the negative lens constitute a junction lens. The method according to claim 1 or 4,
The fourth lens group includes at least one aspherical surface. The method of claim 1,
Wherein the zoom lens system satisfies the following expression.
<Expression>

Here, F _T is the total focal length at the telephoto end of the zoom lens system, and F _W is the total focal length at the wide-angle end of the zoom lens system. The method of claim 1,
The zoom lens system satisfies the following equation.
<Expression>
Fno _{_t} ≤1.9
Here, Fno represents the F-number is _{_t} at the telephoto end. The method of claim 1,
Wherein the zoom lens system satisfies the following expression.
<Expression>
9.5% ≤ BFL / OAL
Here, BFL represents a back focal length of the zoom lens system, and OAL represents a distance from the center of the object-side surface of the most object-side lens of the first lens group to the image plane. The method of claim 1,
The back focal length BFL of the zoom lens system satisfies the following equation.
<Expression>
BFL ≥ 6.4 The method of claim 1,
The zoom lens system, wherein the second lens group and the fourth lens group move, and the first lens group and the third lens group are fixed when zooming from the wide-angle end to the telephoto end. The method of claim 1,
And a distance from the center of the object-side surface of the first lens group to the image surface (OAL) satisfies the following equation.
<Expression>
51.5 ≤ OAL ≤ 53.5 A zoom lens system according to claim 1; And
And an imaging sensor for changing an image formed by the zoom lens system into an electrical signal.

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