KR102066941B1 - Zoom lens system - Google Patents

Abstract

One embodiment of the present invention, in order from the object side to the image 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 And a fourth lens group, wherein the zooming is performed by changing a distance between the first lens group and the fourth lens group, and when zooming, the first lens group and the third lens group are fixed to the image plane and the second lens group is fixed. And the fourth lens group moves, and at least one lens group of the first to fourth lens groups includes at least one aspherical surface, and at least one lens group of the first to fourth lens groups. Provides a zoom lens system comprising a cemented lens.

Description

Zoom lens system

The present invention relates to a zoom lens system, and more particularly to a four-group zoom lens system.

Imaging devices that implement images using CCDs or CMOS have increased in storage capacity as they are 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. 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.

One embodiment of the present invention relates to a four-group zoom lens system.

According to one embodiment of the invention, the first lens group having a positive refractive power in the order from the object side to the image side; A second lens group having negative refractive power; A third lens group having positive refractive power; And a fourth lens group having a positive refractive power, wherein the zooming is performed by changing an interval between the first lens group and the fourth lens group, wherein the first lens group and the third lens group are at the zooming time. The second lens group and the fourth lens group are fixed with respect to the image plane, and at least one lens group of the first to fourth lens groups includes at least one aspherical surface. At least one lens group of the first to fourth lens groups includes a bonded lens, and a zoom lens system satisfying the following conditions is disclosed.

<Condition>

Here, f ₂ is the focal length of the second lens group, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is The f number at the wide-angle end of the zoom lens system is shown.

In the present embodiment, the focal length at the wide-angle end of the zoom lens system may satisfy the following condition.

<Condition>

f _{no -w} ≤ 1.65

In the present embodiment, the third lens group and the fourth lens group may satisfy the following conditions.

<Condition>

1.25 ≤ f ₃ / f ₄ ≤1.75

Here, f3 is a focal length of the third lens, f ₄ represents the focal length of the fourth lens group.

In the present embodiment, the zoom lens system may satisfy the following conditions.

<Condition>

Here, TL is the full length of the zoom lens system, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is the zoom lens system The f number at the wide-angle end is shown.

In the present embodiment, the full length of the zoom lens system may satisfy the following conditions.

<Condition>

TL ≤ 50 mm

Here, TL represents the full length of the zoom lens system.

here

In the present embodiment, the first lens group includes a first lens, a second lens, and a third lens arranged in the order from the object side to the image side, and includes the first lens, the second lens, and the first lens. The three lenses may satisfy the following conditions.

<Condition>

n ₁ ≥2.0

n ₂ ≥1.83

n ₃ ≥1.8

Here, n ₁ represents the refractive index at the d line of the first lens, n ₂ represents the refractive index at the d line of the second lens, n ₃ represents the refractive index at the d line of the third lens.

In example embodiments, the first lens may be a negative lens, the second lens may be a positive lens, and the third lens may be a positive lens.

In the present embodiment, the zoom lens system may satisfy the following conditions.

<Condition>

11 ≤ f _t / f _w

Here, f _w denotes a focal length at the wide-angle end of the zoom lens system, and f _t denotes a focal length at the telephoto end of the zoom lens system.

Another embodiment of the present invention, the first lens group having a positive refractive power in the order from the object side to the image side; A second lens group having negative refractive power; A third lens group having positive refractive power; And a fourth lens group having a positive refractive power, wherein the zooming is performed by changing an interval between the first lens group and the fourth lens group, wherein the first lens group and the third lens group are at the zooming time. The zoom lens system is fixed to the image plane, the second lens group and the fourth lens group are moved, and at least one lens group of the first to fourth lens groups includes a junction lens. To start.

In the present embodiment, the total number of lenses constituting the first to fourth lens groups may be 9 or less.

In the present embodiment, the zoom lens system may satisfy the following conditions.

<Condition>

TL ≤ 50 mm

11 ≤ f _t / f _w

Here, TL denotes the overall length of the zoom lens system, f _w denotes the focal length at the wide-angle end of the zoom lens system, and f _t denotes the focal length at the telephoto end of the zoom lens system.

In the present exemplary embodiment, at least one of the first lens group and the second lens group includes a junction lens, and at least one of the third lens group and the fourth lens group has at least one surface having an aspherical surface. It may include.

In the present embodiment, the focal length at the wide-angle end of the zoom lens system may satisfy the following condition.

<Condition>

f _{no -w} ≤ 1.65

In the present embodiment, the zoom lens system may satisfy the following conditions.

<Condition>

Here, TL is the full length of the zoom lens system, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is the zoom lens system The f number at the wide-angle end is shown.

According to one embodiment of the present invention as described above, it is possible to provide a compact and high magnification bright zoom lens system.

1 schematically shows a zoom lens system according to an embodiment of the present invention.
FIG. 2 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the zoom lens system illustrated in FIG. 1.
FIG. 3 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at an intermediate end of the zoom lens system illustrated in FIG. 1.
4 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion in the telephoto end of the zoom lens system illustrated in FIG. 1.
5 schematically shows a zoom lens system according to another embodiment of the present invention.
FIG. 6 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the zoom lens system illustrated in FIG. 5.
FIG. 7 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at an intermediate end of the zoom lens system illustrated in FIG. 5.
FIG. 8 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion in the telephoto end of the zoom lens system illustrated in FIG. 5.
9 schematically shows a zoom lens system according to another embodiment of the present invention.
FIG. 10 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the zoom lens system illustrated in FIG. 9.
FIG. 11 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at an intermediate end of the zoom lens system illustrated in FIG. 9.
FIG. 12 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion in the telephoto end of the zoom lens system illustrated in FIG. 9.
13 schematically shows a zoom lens system according to another embodiment of the present invention.
FIG. 14 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the zoom lens system shown in FIG.
FIG. 15 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the intermediate stage of the zoom lens system illustrated in FIG. 13.
FIG. 16 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion in the telephoto end of the zoom lens system illustrated in FIG. 13.
17 schematically shows a zoom lens system according to another embodiment of the present invention.
18 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the zoom lens system illustrated in FIG. 17.
FIG. 19 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion at the intermediate stage of the zoom lens system illustrated in FIG. 17.
FIG. 20 illustrates aberration diagrams related to longitudinal spherical aberration, astigmatism, and distortion in the telephoto end of the zoom lens system illustrated in FIG. 17.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. Effects and features of the present invention, and methods of achieving them will be apparent with reference to the embodiments described below in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various forms.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be denoted by the same reference numerals, and redundant description thereof will be omitted. .

In the following embodiments, the terms first, second, etc. are used for the purpose of distinguishing one component from other components rather than a restrictive meaning.

In the following examples, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise.

In the following examples, the terms including or having have meant that there is a feature or component described in the specification and does not preclude the possibility of adding one or more other features or components.

In the drawings, components may be exaggerated or reduced in size for convenience of description. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, and thus the present invention is not necessarily limited to the illustrated.

1, 5, 9, 13, and 17 illustrate a zoom lens system according to an embodiment of the present invention.

1, 5, 9, 13, and 17, the zoom lens system includes the first lens group 10 and the second lens group in the order from the object side O to the image side I. FIG. 20, the third lens group 30 and the fourth lens group 40.

The first lens group 10 has a positive refractive power. The first lens group 10 may include three lenses. For example, the first lens group 10 may include a first lens 11, a second lens 12, and a third lens 13. The first lens 11 may be a negative lens, the second lens 12 may be a positive lens, and the third lens 13 may be a positive lens. The first lens 11, the second lens 12, and the third lens 13 may be a meniscus lens having a convex surface directed toward the object side (O).

The second lens group 20 has negative refractive power. The second lens group 20 may include three lenses. For example, the second lens group 20 may include a fourth lens 21, a fifth lens 22, and a sixth lens 23. The fourth lens 21 may be a negative lens, and the fifth lens 22 and the sixth lens 23 may be positive lenses. The fourth lens 21 may be a meniscus lens with a convex surface directed toward the object side O, the fifth lens 22 may be a biconvex lens, and the sixth lens 23 may have an object with a convex surface. It may be a meniscus lens facing the side (O).

The third lens group 30 has a positive refractive power. The third lens group 30 may include two lenses. For example, the third lens group 30 may include a seventh lens 31 and an eighth lens 32. The seventh lens 31 may be a positive lens, and the eighth lens 32 may be a negative lens. The seventh lens 31 may be a biconvex lens, and the eighth lens 32 may be a meniscus lens having a convex surface directed toward the object side (O).

The third lens group 30 may include an aperture stop ST. The aperture stop ST may be disposed at the object side O of the third lens group 30, for example, at the object side O of the seventh lens 31.

The fourth lens group 40 has a positive refractive power. The fourth lens group 40 may include one lens. For example, the fourth lens group 40 may include a ninth lens 41 that is a positive lens. For example, the ninth lens 41 may be a biconvex lens.

An optical block G such as an optical filter or a face plate may be disposed between the fourth lens group 40 and the image plane IP.

In the zoom lens system according to the exemplary embodiment of the present invention, the interval between the first lens group and the fourth lens group 10, 20, 30, 40 is changed during zooming. When zooming, the second lens group 20 and the fourth lens group 40 move, and the first lens group 10 and the third lens group 30 are fixed to the image plane IP and do not move. Therefore, the overall length of the zoom lens system does not change during zooming. In the present specification, the full length represents a distance from the object side surface of the lens (eg, the first lens 11) disposed on the object side O of the first lens group 10 to the image plane IP.

Upon zooming from the wide-angle end to the telephoto end, the second lens group 20 moves toward the image plane IP. For example, the second lens group 20 may move along the trajectory of a shown in FIGS. 1, 5, 9, 13, and 17. When the second lens group 20 moves, the fourth lens group 40 may perform focusing to correct an image surface variation according to a change in object distance. The trajectories of b shown in solid lines and the traces of c shown in dotted lines in FIGS. 1, 5, 9, 13, and 17 are telephoto at a wide-angle end when focusing on a distant object and a near object, respectively. The movement trajectory of the fourth lens group 40 for correcting the fluctuation of the image according to the zooming to the stage is shown.

At least one lens group of the first lens group 10 to the fourth lens group 10, 20, 30, 40 may include at least one aspherical surface. For example, at least one lens group of the third lens group 30 and the fourth lens group 40 may include an aspherical lens. In an embodiment, the seventh lens 31 of the third lens group 30 may have both an object-side surface and an image-side surface aspherical, and the ninth lens 41 of the fourth lens group 40 may be an object. Both the side and image side may be aspherical.

At least one lens group of the first to fourth lens groups 10, 20, 30, and 40 may include at least one bonding lens. For example, at least one lens group of the first lens group 10 and the second lens group 20 may include a bonding lens. In an embodiment, the first lens 11 and the second lens 12 of the first lens group 10 may form a junction lens, the fifth lens 22 and the second lens group 20. The sixth lens 23 may form a junction lens.

The zoom lens system according to embodiments of the present invention may satisfy the following <Condition 1>.

<Condition 1>

Here, f ₂ is the focal length of the second lens group 20, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is The f number at the wide-angle end of the zoom lens system is shown.

<Condition 1> defines the relationship between the ratio of the focal length of the second lens group 20 to the focal length at the wide-angle end and the telephoto end of the zoom lens system and the f number at the wide-angle end of the zoom lens system. If the value of <Condition 1> is out of the upper limit value, the amount of movement due to the zooming of the second lens group 20 is increased, making it difficult to miniaturize the zoom lens system, and the number f at the wide-angle end is increased to obtain the zoom lens system. The quality of the image may be degraded. If the value of <Condition 1> is out of the lower limit, the refractive power of the second lens group 20 becomes strong, and the change in the focus position due to zooming becomes severe, making it difficult to secure the optical performance of the zoom lens system.

The zoom lens system according to the embodiments of the present invention may satisfy the following <Condition 2>.

<Condition 2>

1.25 ≤ f ₃ / f ₄ ≤1.75

Here, f3 is a focal length of the third lens group (30), f ₄ represents the focal length of the fourth lens group (40).

<Condition 2> defines the ratio of the focal length of the third lens group 30 to the focal length of the fourth lens group 40. If the value of <Condition 2> is outside the upper limit, the fourth lens group 40 is enlarged (for example, the moving distance of the fourth lens group 40 is increased), and the fourth lens group 40 is not moved. The fluctuation of the aberration is large. If the value of <Condition 2> is outside the lower limit, the refractive power of the fourth lens group 40 is weakened, which increases the moving distance of the fourth lens group 40 for focusing and makes it difficult to miniaturize the zoom lens system.

The zoom lens system according to the embodiments of the present invention may satisfy the following <Condition 3>.

<Condition 3>

Where TL is the overall length of the zoom lens system, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, and f _{no -w} is the wide-angle end of the zoom lens system. Indicates the f number.

<Condition 3> defines the relationship between the ratio of the focal length at the wide-angle end and the telephoto end of the zoom lens system to the full length of the zoom lens system and the f number at the wide-angle end of the zoom lens system. if, If the value of <Condition 3> is out of the upper limit, it is difficult to secure the performance of the zoom lens system when the magnification changes according to the zooming from the wide-angle end to the telephoto end. Miniaturization of the zoom lens system becomes difficult.

The zoom lens system according to the embodiments of the present invention may satisfy the following <Condition 4>.

<Condition 4>

n ₁ ≥2.0

n ₂ ≥1.83

n ₃ ≥1.8

Here, n ₁ is the refractive index at the d line of the first lens 11, n ₂ is the refractive index at the d line of the second lens 12, n ₃ is a d line of the third lens 13 Refractive index is shown.

The zoom lens system according to the embodiments of the present invention may satisfy the following <Condition 5>.

<Condition 5>

f _{no -w} ≤ 1.65

<Condition 5> defines the f number at the wide-angle end of the zoom lens system. The zoom lens system according to embodiments of the present invention can obtain a high quality image even with a small amount of light.

The zoom lens system according to the embodiments of the present invention may satisfy the following condition 6.

<Condition 6>

TL ≤ 50 mm

Here, TL represents the full length of the zoom lens system.

<Condition 6> defines the overall length of the zoom lens system. The zoom lens system according to embodiments of the present invention may provide a compact zoom lens system having a full length, that is, a distance from the object-side surface of the first lens 11 to the image plane IP is about 50 mm or less.

The zoom lens system according to embodiments of the present invention may satisfy the following <Condition 7>.

<Condition 7>

11 ≤ f _t / f _w

Here, f _w denotes a focal length at the wide-angle end of the zoom lens system, and f _t denotes a focal length at the telephoto end of the zoom lens system.

<Condition 7> defines the magnification of the zoom lens system. A zoom lens system according to embodiments of the present invention may provide about 11 times or more magnification.

Since the zoom lens system having high optical performance as in the embodiments of the present invention can provide a small lens and a high magnification bright lens system, it can be used in a surveillance camera capable of acquiring a high quality image not only during the daytime but also at night when the amount of light is low. . The zoom lens system according to the exemplary embodiments of the present invention includes a relatively small number of lenses of nine or less, so that the high-performance zoom lens system as described above can be implemented.

As another embodiment, a zoom lens system such as embodiments of the present invention can be used in an imaging device such as a digital video camera or a digital still camera.

An imaging device having a zoom lens system according to embodiments of the present invention may be configured such that light incident on the object side O of the zoom lens system reaches a solid-state imaging device provided on an image plane and forms an image. As the solid-state imaging device, a charge coupled device (CCD), a complementary metal-oxide semiconductor device (CMOS) sensor, or the like may be used.

The definition of aspherical surface (ASP) in the embodiments of the present invention is as follows.

The aspherical shape of the zoom lens according to the embodiment of the present invention has the z-axis in the optical axis direction and the h-axis in the direction perpendicular to the optical axis direction. It can be represented as Where z is the distance from the vertex of the lens in the optical axis direction, h is the distance in the direction perpendicular to the optical axis, K is the conic constant, A, B, and C are aspherical coefficients, and c is The inverse of the radius of curvature at the vertex of the lens is shown (1 / R).

Hereinafter, design data of a zoom lens system according to an exemplary embodiment of the present invention will be described with reference to [Table 1] to [Table 15].

In the design data, R is the radius of curvature [mm] of each lens surface, and Dn is the distance between the lens surface and the lens surface on the optical axis, and represents the thickness of the lens or the distance between the lens and the lens. The units of R and Dn are both mm. nd represents the refractive index of each lens in d line, and vd represents the Abbe number of each lens in d line.

The effective focal length (EFL) is the effective focal length in mm, fno is the f number, ω is the half angle of view in °, and D5, D10, D15, and D17 are the variable distances in mm. ].

Table 3 shows aspherical surface coefficients. The notation Em (m is an integer) in the numerical value of aspherical coefficients means × 10 ^-m .

2 to 4 show longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end, middle end, and telephoto end of the zoom lens system shown in FIG. 1, respectively. Longitudinal spherical aberration is shown for light with wavelengths of about 6.2800 nm, 546.0700 nm, and 435.8400 nm, while astigmatism and distortion are shown for light with 546.0700 nm wavelength. In astigmatism, the dotted line represents tangential astigmatism and the solid line represents sagittal astigmatism.

Second Embodiment

[Table 4] is the effective focal length (EFL), f number (fno), half angle of view (ω), and variable distance (D5, D10, D15,) of the zoom lens system according to an embodiment of the present invention shown in FIG. D17). Table 6 shows design data of a zoom lens system according to an exemplary embodiment of the present invention shown in FIG. 5.

Table 6 shows aspherical surface coefficients. The notation Em (m is an integer) in the numerical value of aspherical coefficients means × 10 ^-m .

6 to 8 show longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end, middle end, and telephoto end of the zoom lens system shown in FIG. 5, respectively. Longitudinal spherical aberration is shown for light with wavelengths of about 6.2800 nm, 546.0700 nm, and 435.8400 nm, and astigmatism and distortion are shown for light with 546.0700 nm wavelength. In astigmatism, the dotted line represents tangential astigmatism and the solid line represents sagittal astigmatism.

Third Embodiment

[Table 7] shows the effective focal length (EFL), f number (fno), half angle of view (ω), and variable distance (D5, D10, D15,) of the zoom lens system according to an embodiment of the present invention shown in FIG. D17). Table 8 shows design data of a zoom lens system according to an exemplary embodiment of the present invention shown in FIG. 9.

Table 9 shows aspherical surface coefficients. The notation Em (m is an integer) in the numerical value of aspherical coefficients means × 10 ^-m .

10 to 12 show longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end, middle end, and telephoto end of the zoom lens system shown in FIG. 9, respectively. Longitudinal spherical aberration is shown for light with wavelengths of about 6.2800 nm, 546.0700 nm, and 435.8400 nm, and astigmatism and distortion are shown for light with 546.0700 nm wavelength. In astigmatism, the dotted line represents tangential astigmatism and the solid line represents sagittal astigmatism.

Fourth Example

Table 10 shows the effective focal length, the f number, the half angle of view, and the variable distance of the zoom lens system according to the exemplary embodiment of the present invention shown in FIG. Table 11 shows design data of a zoom lens system according to an exemplary embodiment of the present invention illustrated in FIG. 13.

Table 12 shows aspherical surface coefficients. The notation Em (m is an integer) in the numerical value of aspherical coefficients means × 10 ^-m .

14 to 16 show longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end, middle end, and telephoto end of the zoom lens system shown in FIG. 13, respectively. Longitudinal spherical aberration is shown for light with wavelengths of about 6.2800 nm, 546.0700 nm, and 435.8400 nm, and astigmatism and distortion are shown for light with 546.0700 nm wavelength. In astigmatism, the dotted line represents tangential astigmatism and the solid line represents sagittal astigmatism.

Fifth Embodiment

[Table 13] shows the effective focal length, f number, half angle of view, and variable distance of the zoom lens system according to the exemplary embodiment of the present invention shown in FIG. Table 14 shows design data of a zoom lens system according to an exemplary embodiment of the present invention illustrated in FIG. 17.

Table 15 shows aspherical surface coefficients. The notation Em (m is an integer) in the numerical value of aspherical coefficients means × 10 ^-m .

18 to 20 show longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end, middle end, and telephoto end of the zoom lens system shown in FIG. 14, respectively. Longitudinal spherical aberration is shown for light with wavelengths of about 6.2800 nm, 546.0700 nm, and 435.8400 nm, and astigmatism and distortion are shown for light with 546.0700 nm wavelength. In astigmatism, the dotted line represents tangential astigmatism and the solid line represents sagittal astigmatism.

[Table 16] below shows that the zoom lens system according to the embodiments of the present invention satisfies <Condition 1> to <Condition 7>.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will include such modifications and variations as long as they fall within the spirit of the invention.

10: first lens group 11: first lens
12: second lens 13: third lens
20: second lens group 21: fourth lens
22: fifth lens 23: sixth lens
30: third lens group 31: seventh lens
32: eighth lens 40: fourth lens group
41: ninth lens

Claims (15)

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;
A third lens group having positive refractive power; And
Including a fourth lens group having positive refractive power,
Zooming is performed by varying an interval between the first lens group and the fourth lens group, and when the zooming is performed, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group and the The fourth lens group moves,
At least one lens group of the first to fourth lens groups includes at least one aspherical surface,
At least one lens group of the first to fourth lens groups includes a bonded lens, and satisfies the following conditions.
<Condition>

Here, f ₂ is the focal length of the second lens group, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is The f number at the wide-angle end of the zoom lens system is shown. The method of claim 1,
A focal length at the wide-angle end of the zoom lens system satisfies the following condition.
<Condition>
f _{no -w} ≤ 1.65 The method according to claim 1 or 2,
The zoom lens system, wherein the third lens group and the fourth lens group satisfy the following conditions.
<Condition>
1.25 ≤ f ₃ / f ₄ ≤1.75
Here, f3 is a focal length of the third lens, f ₄ represents the focal length of the fourth lens group. The method of claim 1,
The zoom lens system satisfies the following conditions.
<Condition>

Here, TL is the full length of the zoom lens system, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, f _{no -w} is the zoom lens system The f number at the wide-angle end is shown. The method according to claim 1 or 4,
The full length of the zoom lens system satisfies the following conditions.
TL ≤ 50 mm
Here, TL represents the full length of the zoom lens system. The method of claim 1,
The first lens group includes a first lens, a second lens and a third lens arranged in the order from the object side to the image side,
The first lens, the second lens and the third lens satisfy the following conditions.
<Condition>
n ₁ ≥2.0
n ₂ ≥1.83
n ₃ ≥1.8
Here, n ₁ represents the refractive index at the d line of the first lens, n ₂ represents the refractive index at the d line of the second lens, n ₃ represents the refractive index at the d line of the third lens. The method of claim 6,
And the first lens is a negative lens, the second lens is a positive lens, and the third lens is a positive lens. The method of claim 1,
The zoom lens system satisfies the following conditions.
<Condition>
11 ≤ f _t / f _w
Here, f _w denotes a focal length at the wide-angle end of the zoom lens system, and f _t denotes a focal length at the telephoto end of the zoom lens system. As a zoom lens system, in the 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;
A third lens group having positive refractive power; And
Including a fourth lens group having positive refractive power,
Zooming is performed by varying an interval between the first lens group and the fourth lens group, and when the zooming is performed, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group and the The fourth lens group moves,
At least one lens group of the first lens group to the fourth lens group includes a bonding lens,
And the third lens group and the fourth lens group satisfy condition 1 below, and the zoom lens system satisfy condition 2.
<Condition 1>
1.25 ≤ f3 / f4 ≤1.75
<Condition 2>
TL ≤ 50 mm
Here, f3 represents the focal length of the third lens group, f4 represents the focal length of the fourth lens group, and TL represents the full length of the zoom lens system. The method of claim 9,
The total number of lenses constituting the first to fourth lens groups is nine or less. The method of claim 9 or 10,
The zoom lens system satisfies the following condition 3.
<Condition 3>
11 ≤ f _t / f _w
Here, f _w denotes a focal length at the wide-angle end of the zoom lens system, and f _t denotes a focal length at the telephoto end of the zoom lens system. The method of claim 11,
At least one of the first lens group and the second lens group includes a junction lens, and at least one of the third lens group and the fourth lens group includes a lens having at least one surface aspherical. . The method of claim 11,
A focal length f _no-w at the wide-angle end of the zoom lens system satisfies the following condition.
<Condition>
f _no-w ≤ 1.65 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;
A third lens group having positive refractive power; And
Including a fourth lens group having positive refractive power,
Zooming is performed by varying an interval between the first lens group and the fourth lens group, and when the zooming is performed, the first lens group and the third lens group are fixed with respect to an image plane, and the second lens group and the The fourth lens group moves,
At least one lens group of said first lens group to said fourth lens group includes a bonded lens, and satisfies the following condition.
<Condition>

Where TL is the overall length of the zoom lens system, f _w is the focal length at the wide-angle end of the zoom lens system, f _t is the focal length at the telephoto end of the zoom lens system, and f _no-w is the zoom lens system. The f number at the wide-angle end is shown. The method of claim 14,
The total number of lenses constituting the first to fourth lens groups is nine or less.

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