CN112965227A

CN112965227A - Zoom lens

Info

Publication number: CN112965227A
Application number: CN202110373994.1A
Authority: CN
Inventors: 葛杰; 金兑映; 宋亮
Original assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Current assignee: Liaoning Zhonglan Photoelectric Technology Co Ltd
Priority date: 2021-04-07
Filing date: 2021-04-07
Publication date: 2021-06-15

Abstract

The invention relates to the technical field of imaging, in particular to a zoom lens, which comprises a first lens group with negative focal power, a diaphragm, a second lens group with positive focal power, a third lens group with positive focal power, an optical filter and an image surface, wherein the first lens group with negative focal power, the diaphragm, the second lens group with positive focal power, the third lens group with positive focal power, the optical filter and the image surface are sequentially distributed from an object side to an image; the first lens group, the second lens group, the third lens group, the optical filter and the image plane are distributed along the same optical axis; during zooming from a wide angle position to a telephoto position, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases. The zoom lens has the characteristics of miniaturization and high magnification, and is suitable for small-sized portable electronic mobile equipment.

Description

Zoom lens

Technical Field

The invention relates to the technical field of imaging, in particular to a zoom lens.

Background

With the continuous development of imaging CCD chips, the imaging chips are remarkably improved in volume and imaging quality. The miniaturized photographic lens at the present stage can realize high resolution and can also meet the light and thin size, so the miniaturized photographic lens is popular with consumers.

At present, the miniaturized camera lens adopts a single-focus design, different requirements are difficult to meet when a long-distance scene and a short-distance object are shot at the same time, and shooting of the long-distance scene and the short-distance scene can be met only by equipping a plurality of camera lenses, so that the camera lens is inconvenient. Therefore, a high performance miniaturized lens with a variable focal length has become a trend of high-order electronic products.

Disclosure of Invention

In order to solve the above technical problem, the present invention provides a zoom lens. The zoom lens has smaller volume and variable focal length.

In order to achieve the purpose, the invention adopts the main technical scheme that:

the invention provides a zoom lens, which comprises a first lens group with negative focal power, a diaphragm, a second lens group with positive focal power, a third lens group with positive focal power, an optical filter and an image surface, wherein the first lens group with negative focal power, the diaphragm, the second lens group with positive focal power, the third lens group with positive focal power, the optical filter and the image surface are sequentially distributed from an object side to an image side; the first lens group, the second lens group, the third lens group, the optical filter and the image plane are distributed along the same optical axis; during zooming from a wide angle position to a telephoto position, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases.

Further, the first lens group includes a first lens and a second lens; the second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens group includes a seventh lens; the diaphragm is arranged between the second lens and the third lens; the first lens has negative focal power, and the surface of the image side is a concave surface; the second lens has positive focal power, and the object side surface of the second lens is a convex surface; the third lens has positive focal power, and the surface of the image side is a concave surface; the fourth lens has positive focal power, and the surface of the image side is a concave surface; the fifth lens has negative focal power, and the surface of the image side is a concave surface; the sixth lens has negative focal power, and the surface of the image side is a concave surface; the seventh lens element has positive power, a convex surface on the image side of the paraxial region, and a concave surface on the image side of the paraxial region.

Further, the zoom lens satisfies the following conditional expression:

3<Z＝Ft/Fw<5

2<TTL/IMGH/Z<3.5

wherein Ft is the focal length of the telescopic position of the zoom lens, Fw is the focal length of the wide-angle position of the zoom lens, Z is the ratio of the focal length of the telescopic position to the focal length of the wide-angle position, and TTL is the total length of the zoom lens; and IMGH is the maximum half image height of the zoom lens on an image surface.

Further, the zoom lens also satisfies the following relation:

1.5≤|F1|/Fw≤2.5

where F1 is the focal length of the first lens group, and Fw is the focal length at the wide angle position of the zoom lens.

Further, the zoom lens also satisfies the following relation:

-3≤(Ra+Rb)/(Ra-Rb)≤0

wherein Ra is the curvature radius of the object side surface of the seventh lens, and Rb is the curvature radius of the image side surface of the seventh lens.

Further, the object side and image side surfaces of the first to seventh lenses are aspheric, wherein aspheric coefficients satisfy the following equation:

Z＝cy²/[1+{1－(1+k)c² y²}^+1/2]+A₄y⁴+A₆y⁶+A₈y⁸

+A₁₀y¹⁰+A₁₂y¹²+A₁₄y¹⁴+A₁₆y¹⁶+A₁₈y¹⁸

wherein Z is aspheric sagittal height, c is aspheric paraxial curvature, y is lens caliber, k is cone coefficient, A₄Is a 4-order aspheric coefficient, A₆Is a 6-degree aspheric surface coefficient, A₈Is an 8 th order aspheric surface coefficient, A₁₀Is a 10 th order aspheric surface coefficient, A₁₂Is a 12 th order aspheric surface coefficient, A₁₄Is a 14 th order aspheric coefficient, A₁₆Is a 16-degree aspheric surface coefficient, A₁₈Is an 18-degree aspheric coefficient.

Furthermore, the first to seventh lenses are made of one or two of glass and plastic.

The invention has the beneficial effects that: the zoom lens provided by the invention adopts a plurality of lenses, and the optical lens has the advantages of higher zoom magnification, miniaturization, higher image quality and the like through the matching of the focal power, the surface type, the center thickness of each lens, the axial distance between each lens and the like. The zoom lens has the characteristics of miniaturization and high magnification, and is suitable for small-sized portable electronic mobile equipment.

Drawings

FIG. 1 shows a schematic configuration of a zoom lens of the present invention;

fig. 2A, 2B, and 2C are schematic optical arrangement diagrams showing the zoom lens of embodiment 1 of the present invention in a wide-angle position, an intermediate position, and a telephoto position, respectively;

FIG. 3 is an astigmatic field curves at a wide angle position of a zoom lens according to embodiment 1 of the present invention;

FIG. 4 is a distortion graph showing a zoom lens system according to embodiment 1 of the present invention at a wide angle position;

fig. 5 shows an astigmatic field curvature chart of a zoom lens according to embodiment 1 of the present invention at a telephoto position;

fig. 6 is a distortion graph showing a zoom lens system according to embodiment 1 of the present invention at a telephoto position;

fig. 7A, 7B, and 7C are schematic optical arrangement diagrams showing the zoom lens of embodiment 2 of the present invention in a wide-angle position, an intermediate position, and a telephoto position, respectively;

FIG. 8 is an astigmatic field curves of a zoom lens according to embodiment 2 of the present invention at a wide angle;

FIG. 9 is a distortion graph showing a zoom lens system according to embodiment 2 of the present invention at a wide angle position;

FIG. 10 is an astigmatic field curvature chart of a zoom lens according to embodiment 2 of the present invention at a telephoto position;

fig. 11 is a distortion graph showing a zoom lens system according to embodiment 2 of the present invention at a telephoto position;

fig. 12A, 12B, and 12C are schematic optical arrangement diagrams showing the zoom lens of embodiment 3 of the present invention in a wide-angle position, an intermediate position, and a telephoto position, respectively;

FIG. 13 is an astigmatic field curves of a zoom lens according to embodiment 3 of the present invention at a wide angle;

FIG. 14 is a distortion graph showing a zoom lens system according to embodiment 3 of the present invention at a wide angle position;

FIG. 15 is an astigmatic field curvature chart of a zoom lens according to embodiment 3 of the present invention at a telephoto position;

fig. 16 is a distortion graph showing the zoom lens system according to embodiment 3 of the present invention at the telephoto position.

In the figure: 1: a first lens; 2: a second lens; 3: a third lens; 4: a fourth lens; 5: a fifth lens; 6: a sixth lens; 7: a seventh lens; 8: a diaphragm; 9: an optical filter; 10: and (4) an image plane.

Detailed Description

For the purpose of better explaining the present invention and to facilitate understanding, the present invention will be described in detail by way of specific embodiments with reference to the accompanying drawings.

As shown in fig. 1, the present invention provides a zoom lens. The zoom lens sequentially comprises a first lens group with negative focal power, a diaphragm 8, a second lens group with positive focal power, a third lens group with positive focal power, an optical filter 9 and an image surface 10 from an object side to an image side. During zooming of the zoom lens from the wide angle position to the telephoto position, a distance D1 between the first lens group and the second lens group decreases, and a distance D2 between the second lens group and the third lens group increases; the distance D3 between the third lens group and the filter 9 also changes slightly. Wherein the first lens group includes a first lens 1 and a second lens 2; the second lens group includes a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6; the third lens group includes a seventh lens 7. A diaphragm 8 is placed between the second lens 2 and the third lens 3. Wherein the first to seventh lenses 1 to 7 and the optical filter 9 are distributed on the same optical axis in order from the object side to the image side. The surfaces of the first to seventh lenses 1 to 7 are aspheric surfaces.

Specifically, the first lens 1 has negative optical power, and the image side surface is a concave surface; the second lens 2 has positive focal power, and the object side surface is a convex surface; the third lens 3 has positive focal power, and the surface of the image side is a concave surface; the fourth lens 4 has positive focal power, and the surface on the image side is a concave surface; the fifth lens 5 has negative focal power, and the surface of the image side is a concave surface; the sixth lens 6 has negative focal power, and the image side surface is a concave surface; the seventh lens element 7 has positive power, and has a convex surface on the image side and a concave surface on the image side.

Example 1

Fig. 2A, 2B, and 2C show optical arrangement schematic diagrams of the zoom lens according to embodiment 1 of the present invention at a wide-angle position, an intermediate position, and a telephoto position, respectively. As shown in the drawings, the zoom lens according to the exemplary embodiment of the present invention, in order from an object side to an image side along an optical axis, comprises: the lens comprises a first lens 1, a second lens 2, a diaphragm 8, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an optical filter 9 (an IR sheet) and an image plane 10. The sixth lens element 6 is made of glass, and the other lens elements are made of plastic.

Let Ft be the focal length of the telephoto position of the zoom lens, Fw be the focal length of the wide-angle position of the zoom lens, and the ratio Z of the focal length of the telephoto position to the focal length of the wide-angle position satisfies the following control conditions:

3<Z＝Ft/Fw<5

the zoom multiple of the zoom lens is controlled by the condition, so that the zoom lens is suitable for small-sized mobile equipment such as mobile phones.

2<TTL/IMGH/Z<3.5

Wherein Z is the ratio of the focal length of the telescopic position to the focal length of the wide-angle position, and TTL is the total length (unit millimeter) of the zoom lens; the IMGH is the maximum half image height (unit millimeter) of the zoom lens on the image plane. The zoom lens satisfying the conditional expression can shorten the total length of the lens.

1.5≤|F1|/Fw≤2.5

Where F1 is the focal length of the first lens group, and Fw is the focal length at the wide angle position of the zoom lens. The zoom lens meeting the conditional expression is beneficial to reducing aberration and improving resolving power.

-3≤(Ra+Rb)/(Ra-Rb)≤0

Wherein Ra is the curvature radius of the object side surface of the seventh lens, and Rb is the curvature radius of the image side surface of the seventh lens. The zoom lens meeting the conditional expression is beneficial to the control of shortening the total length of the lens.

In summary, the present invention adopts seven lenses, and by optimally setting the focal power, the surface shape, the center thickness of each lens, and the axial distance between the lenses, the problems of difficult zooming, large lens volume, etc. of the imaging lens are solved.

The design parameters of the lens assembly of the present embodiment refer to the following table:

watch 1 (a)

Watch 1 (b)

Flour mark

K

A4

A6

A8

A10

A12

A14

A16

A18

1

-4.740E+01

-6.274E-03

1.307E-03

-1.694E-04

1.521E-05

-9.434E-07

3.917E-08

-1.035E-09

1.573E-11

2

-5.867E-01

-1.180E-02

2.112E-03

-2.765E-04

3.932E-05

-6.464E-06

1.023E-06

-1.076E-07

5.893E-09

3

-1.639E+01

2.039E-03

-4.735E-04

-3.483E-05

4.362E-05

-9.180E-06

1.037E-06

-7.263E-08

2.963E-09

4

-9.884E+01

2.670E-03

-1.217E-03

2.055E-04

-1.156E-05

-5.790E-07

8.300E-08

-1.268E-09

-1.481E-10

6

9.423E-01

-5.858E-04

1.147E-03

-7.522E-04

1.691E-04

2.776E-05

-2.321E-05

4.983E-06

-4.696E-07

7

9.797E+01

-3.529E-03

6.251E-03

-6.450E-03

3.551E-03

-1.121E-03

2.085E-04

-2.228E-05

1.257E-06

8

-1.702E-01

-3.865E-03

6.190E-03

-6.956E-03

4.108E-03

-1.385E-03

2.774E-04

-3.235E-05

2.022E-06

9

-4.587E+01

1.287E-03

-2.217E-03

-7.879E-05

7.120E-04

-4.191E-04

1.528E-04

-3.527E-05

4.481E-06

10

-3.203E+01

-4.770E-03

-2.279E-03

8.793E-03

-8.518E-03

4.372E-03

-1.276E-03

2.103E-04

-1.812E-05

11

-6.561E-01

-1.415E-02

-4.330E-04

1.067E-02

-1.018E-02

4.684E-03

-1.109E-03

1.239E-04

-3.812E-06

12

-8.308E+01

1.125E-02

-1.447E-02

8.018E-03

-1.903E-03

-7.562E-04

7.326E-04

-2.168E-04

2.841E-05

13

-2.481E+01

-8.094E-04

1.279E-03

-3.564E-03

4.261E-03

-2.731E-03

1.038E-03

-2.236E-04

2.498E-05

14

-3.031E+01

7.526E-03

-9.293E-04

3.400E-05

1.538E-05

-3.389E-06

3.583E-07

-2.176E-08

7.260E-10

15

3.590E+00

7.547E-03

-1.325E-03

4.494E-04

-2.105E-04

5.300E-05

-7.327E-06

5.794E-07

-2.482E-08

Watch 1 (c)

Center thickness	Wide angle position	Intermediate position	Telescope position
				D1	8.542	2.932	0.511
D2	4.997	9.695	15.687
				D3	0.874	0.611	0.827

In this embodiment, the lens meets the requirements of the above claims, and the specific parameters thereof are shown in the following table:

watch 1 (d)

Table one (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 1. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm). Table one (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 1. Table one (c) shows distance data of the zoom lens of embodiment 1 at different positions. Where D1 is a distance between the second lens 2 and the third lens 3, D2 is a distance between the sixth lens 6 and the seventh lens 7, and D3 is a distance between the seventh lens 7 and the filter 9.

According to the table one (a), the table one (b), and the table one (c), the lens shape and the attributes of the lens in the present embodiment are shown clearly, which indicates that the imaging lens in the present embodiment has a higher zoom power and a higher image quality.

Referring to fig. 2A, fig. 2B and fig. 2C, which are schematic diagrams of optical arrangements of the zoom lens of embodiment 1 at a wide-angle position, an intermediate position and a telephoto position, respectively, it can be seen that the close arrangement of the lenses of the lens can realize smaller structural features of the lens.

According to the table (d) and the astigmatic field curvature diagram in fig. 3, it is clearly shown that the maximum difference between the S-line and the T-line of the astigmatism of the lens at the wide-angle position is about 0.02mm, and the maximum value of the field curvature is about 0.04, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion graphs in table one (d) and fig. 4, it is clearly shown that the maximum distortion value of the lens is about 27% at the wide angle position after the lens meets the requirements of the claims, which indicates that the lens has good capability of improving distortion.

According to the chart (d) and the astigmatic field curvature diagram in fig. 5, it is clearly shown that the maximum difference between the astigmatism S-line and the T-line of the lens at the telephoto position is about 0.1mm, and the maximum value of the field curvature is about 0.08, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion graphs in table (d) and fig. 6, it is clearly shown that after the lens meets the requirements of the claims, the maximum distortion value of the lens at the telephoto position is about 3%, which indicates that the lens has a good capability of improving the distortion.

Referring to fig. 3 to 6, graphs of astigmatic field curvatures and distortions at the wide angle position and the telephoto position, respectively, of the zoom lens of embodiment 1 are controlled to be within a small range. The lens has good imaging effect at the wide-angle position and the telescopic position.

Example 2

Fig. 7A, 7B, and 7C show optical arrangement schematic diagrams of the zoom lens according to embodiment 2 of the present invention at a wide-angle position, an intermediate position, and a telephoto position, respectively. As shown in the drawings, the zoom lens according to the exemplary embodiment of the present invention, in order from an object side to an image side along an optical axis, comprises: the lens comprises a first lens 1, a second lens 2, a diaphragm 8, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an optical filter 9 and an image plane 10. The first lens element 1, the fourth lens element 4 and the sixth lens element 6 are made of glass, and the other lens elements are made of plastic.

watch two (a)

Lens	Surface number	Surface type	Radius of curvature	Thickness of	Material Property (Nd: Vd)
						Article surface	Article (A)	Spherical surface	Infinite number of elements	Infinite number of elements
p1
		1	Aspherical surface	-14.980	0.879	1.69:49.7
							2	Aspherical surface	4.768	1.808
	p2	3	Aspherical surface	6.763	1.039	1.66：20.3
							4	Aspherical surface	14.814	D1
		Diaphragm	Spherical surface	Infinite number of elements	-0.011
p3							6	Aspherical surface	5.145	0.980	1.54：55.9
		7	Aspherical surface	29.743	0.689
p4							8	Aspherical surface	6.745	1.204	1.84:37.8
		9	Aspherical surface	-33.879	0.224
p5							10	Aspherical surface	-8.658	0.300	1.66：20.3
		11	Aspherical surface	5.670	0.500
p6							12	Aspherical surface	12.694	0.517	1.77：33.5
		13	Aspherical surface	-75.504	D2
p7							14	Aspherical surface	10.014	2.407	1.549:55.9
		15	Aspherical surface	-130.514	D3
IR							16	Spherical surface	Infinite number of elements	0.230	1.52：64.2
		17	Spherical surface	Infinite number of elements	0.333
Image plane							Image	Spherical surface	Infinite number of elements	0

Watch two (b)

Watch two (c)

Center thickness	Wide angle position	Intermediate position	Telescope position
				D1	10.047	2.932	0.511
D2	4.795	9.695	15.687
				D3	1.281	1.173	0.704

watch two (d)

Table two (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 2. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm). Table two (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 2. Table two (c) shows distance data of the zoom lens of embodiment 2 at different positions. Where D1 is a distance between the second lens 2 and the third lens 3, D2 is a distance between the sixth lens 6 and the seventh lens 7, and D3 is a distance between the seventh lens 7 and the filter 9.

According to the second table (a), the second table (b), and the second table (c), the lens shape and the attributes of the lens in the present embodiment are clearly shown, which indicates that the imaging lens in the present embodiment has a higher zoom power and a higher image quality.

Referring to fig. 7A, 7B and 7C, which are schematic diagrams of optical arrangements of the zoom lens of embodiment 2 at a wide-angle position, an intermediate position and a telephoto position, respectively, it can be seen that the close arrangement of the lenses of the lens can realize smaller structural features of the lens.

According to the second table (d) and the astigmatic field curvature diagram in fig. 8, it is clearly shown that the maximum difference between the S-line and the T-line of the astigmatism of the lens at the wide-angle position is about 0.02mm, and the maximum value of the field curvature is about 0.04, indicating that the lens has better capability of improving astigmatism and field curvature.

According to the distortion graphs in table two (d) and fig. 9, it is clearly shown that, after the lens meets the requirements of the claims, the maximum distortion value of the lens is about 27% at the wide-angle position, which indicates that the lens has good capability of improving distortion.

According to the second table (d) and the astigmatic field curvature chart in fig. 10, it is clearly shown that the maximum difference between the astigmatic S line and the astigmatic T line of the lens at the telephoto position is about 0.08mm, and the maximum field curvature is about 0.08, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion graphs in table two (d) and fig. 11, it is clearly shown that after the lens meets the requirements of the claims, the maximum distortion value of the lens at the telephoto position is about 2.4%, which indicates that the lens has a good capability of improving distortion.

Referring to fig. 8 to 11, graphs of astigmatic field curvatures and distortions at the wide angle position and the telephoto position, respectively, of the zoom lens of embodiment 2 are controlled to be within a small range. The lens has good imaging effect at the wide-angle position and the telescopic position.

Example 3

Fig. 12A, 12B, and 12C show optical arrangement schematic diagrams of the zoom lens according to embodiment 3 of the present invention at a wide angle position, an intermediate position, and a telephoto position, respectively. As shown in the drawings, the zoom lens according to the exemplary embodiment of the present invention, in order from an object side to an image side along an optical axis, comprises: the lens comprises a first lens 1, a second lens 2, a diaphragm 8, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an optical filter 9 and an image plane 10. The second lens element 2 and the sixth lens element 6 are made of glass, and the other lens elements are made of plastic.

watch III (a)

Watch III (b)

Flour mark

K

A4

A6

A8

A10

A12

A14

A16

A18

1

9.311E+01

-6.513E-03

1.403E-03

-1.957E-04

1.881E-05

-1.231E-06

5.360E-08

-1.483E-09

2.363E-11

2

-5.868E-01

-1.262E-02

2.524E-03

-4.970E-04

1.250E-04

-2.909E-05

4.778E-06

-4.717E-07

2.462E-08

3

-1.651E+01

1.425E-03

-4.257E-04

1.795E-05

1.740E-05

-3.105E-06

2.836E-07

-2.281E-08

1.371E-09

4

-9.453E+01

1.979E-03

-1.051E-03

1.899E-04

-1.857E-05

2.777E-06

-5.286E-07

5.474E-08

-2.716E-09

6

9.213E-01

-8.758E-04

1.713E-03

-1.451E-03

6.403E-04

-1.603E-04

2.235E-05

-1.550E-06

3.730E-08

7

9.828E+01

-3.398E-03

5.424E-03

-5.458E-03

2.972E-03

-9.353E-04

1.743E-04

-1.877E-05

1.071E-06

8

-2.374E-01

-3.806E-03

5.421E-03

-5.922E-03

3.456E-03

-1.162E-03

2.334E-04

-2.747E-05

1.747E-06

9

-5.009E+01

-1.927E-03

7.553E-03

-1.221E-02

8.968E-03

-3.681E-03

9.107E-04

-1.359E-04

1.136E-05

10

-2.300E+01

-8.186E-03

9.117E-03

-6.753E-03

2.547E-03

-1.666E-04

-1.690E-04

5.219E-05

-5.977E-06

11

-6.894E-01

-1.336E-02

-2.801E-03

1.435E-02

-1.356E-02

6.485E-03

-1.674E-03

2.269E-04

-1.392E-05

12

-6.730E+01

1.452E-02

-2.443E-02

2.064E-02

-1.029E-02

2.453E-03

1.194E-05

-1.250E-04

2.254E-05

13

-9.124E+01

6.543E-04

-4.004E-03

2.628E-03

6.574E-04

-1.577E-03

8.389E-04

-2.084E-04

2.500E-05

14

-3.091E+01

6.943E-03

-8.174E-04

1.103E-04

-3.715E-05

9.031E-06

-1.203E-06

8.910E-08

-3.465E-09

15

9.761E+01

1.253E-02

-4.597E-03

2.216E-03

-7.774E-04

1.598E-04

-1.959E-05

1.426E-06

-5.714E-08

Watch III (c)

Center thickness	Wide angle position	Intermediate position	Telescope position
				D1	8.219	3.015	0.359
D2	4.831	9.172	15.094
				D3	0.983	0.412	0.602

watch III (d)

Table three (a) shows the surface type, radius of curvature, thickness, and material of each lens of the optical lens of example 3. Wherein the unit of the radius of curvature and the thickness are both millimeters (mm). Table three (b) shows surface aspherical coefficients of the respective lenses of the optical lens of example 3. Table three (c) shows distance data of the zoom lens of embodiment 3 at different positions. Where D1 is a distance between the second lens 2 and the third lens 3, D2 is a distance between the sixth lens 6 and the seventh lens 7, and D3 is a distance between the seventh lens 7 and the filter 9.

According to the third table (a), the third table (b) and the third table (c), the lens shape and each attribute of the lens in the current embodiment are shown clearly, which indicates that the imaging lens in the present embodiment has a higher zoom magnification and a higher image quality.

Referring to fig. 12A, 12B and 12C, which are schematic diagrams of optical arrangements of the zoom lens of embodiment 3 at a wide-angle position, an intermediate position and a telephoto position, respectively, it can be seen that the close arrangement of the lenses of the lens can realize smaller structural features of the lens.

According to the chart of the astigmatic field curves in table three (d) and fig. 13, it is clearly shown that the maximum difference between the astigmatic S line and the astigmatic T line of the lens at the wide-angle position is about 0.04mm, and the maximum field curve is about 0.04, indicating that the lens has better capability of improving astigmatism and field curve.

From table three (d) and the distortion graph in fig. 14, it is clearly shown that after the lens meets the requirements of the claims, the maximum distortion value of the lens is about 28% at the wide-angle position, which indicates that the lens has a good capability of improving distortion.

According to the astigmatism field curvature diagrams in table three (d) and fig. 15, it is clearly shown that the maximum difference between the astigmatism S-line and the T-line of the lens at the telephoto position is about 0.1mm, and the maximum value of the field curvature is about 0.1, which indicates that the lens has better capability of improving astigmatism and field curvature.

According to the distortion graphs in table three (d) and fig. 16, it is clearly shown that after the lens meets the requirements of the claims, the maximum distortion value of the lens at the telephoto position is about 3%, which indicates that the lens has a good capability of improving the distortion.

Referring to fig. 13 to 16, graphs of astigmatic field curvatures and distortions at the wide angle position and the telephoto position, respectively, of the zoom lens of embodiment 3 are controlled to be within a small range. The lens has good imaging effect at the wide-angle position and the telescopic position.

Although embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are illustrative and not restrictive, and that those skilled in the art may make changes, modifications, substitutions and alterations to the above embodiments without departing from the scope of the present invention.

Claims

1. A zoom lens is characterized by comprising a first lens group with negative focal power, a diaphragm, a second lens group with positive focal power, a third lens group with positive focal power, an optical filter and an image surface which are sequentially distributed from an object side to an image side; the first lens group, the second lens group, the third lens group, the optical filter and the image plane are distributed along the same optical axis;

during zooming from a wide angle position to a telephoto position, a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases.

2. The zoom lens according to claim 1, wherein the first lens group includes a first lens and a second lens; the second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens group includes a seventh lens; the diaphragm is arranged between the second lens and the third lens;

the first lens has negative focal power, and the surface of the image side is a concave surface; the second lens has positive focal power, and the object side surface of the second lens is a convex surface; the third lens has positive focal power, and the surface of the image side is a concave surface; the fourth lens has positive focal power, and the surface of the image side is a concave surface; the fifth lens has negative focal power, and the surface of the image side is a concave surface; the sixth lens has negative focal power, and the surface of the image side is a concave surface; the seventh lens element has positive power, a convex surface on the image side of the paraxial region, and a concave surface on the image side of the paraxial region.

3. The zoom lens according to claim 1, wherein the zoom lens satisfies the following conditional expression:

3<Z＝Ft/Fw<5

2<TTL/IMGH/Z<3.5

4. The zoom lens according to claim 1, wherein the zoom lens further satisfies the following relationship:

1.5≤|F1|/Fw≤2.5

5. The zoom lens according to claim 1, wherein the zoom lens further satisfies the following relationship:

-3≤(Ra+Rb)/(Ra-Rb)≤0

6. The zoom lens according to claim 2, wherein the object-side and image-side surfaces of the first to seventh lenses are each aspherical, and wherein aspherical coefficients satisfy the following equations:

Z＝cy²/[1+{1－(1+k)c²y²}^+1/2]+A₄y⁴+A₆y⁶+A₈y⁸+A₁₀y¹⁰+A₁₂y¹²+A₁₄y¹⁴+A₁₆y¹⁶+A₁₈y¹⁸

7. The zoom lens according to claim 2, wherein the first through seventh lenses are made of one or two of glass and plastic.