CN113933974A

CN113933974A - Wide-angle lens and imaging apparatus

Info

Publication number: CN113933974A
Application number: CN202111539428.XA
Authority: CN
Inventors: 尚博文; 鲍宇旻
Original assignee: Jiangxi Lianchuang Electronic Co Ltd
Current assignee: Jiangxi Lianchuang Electronic Co Ltd
Priority date: 2021-12-16
Filing date: 2021-12-16
Publication date: 2022-01-14
Anticipated expiration: 2041-12-16
Also published as: CN113933974B

Abstract

The invention discloses a wide-angle lens and imaging equipment, the wide-angle lens comprises the following components in sequence from an object side to an imaging surface along an optical axis: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; a second lens with negative focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive refractive power, an object-side surface of which is convex; a fourth lens having a positive refractive power, both the object-side surface and the image-side surface of the fourth lens being convex; a diaphragm; a fifth lens element having a negative refractive power, both the object-side surface and the image-side surface of the fifth lens element being concave; the object side surface and the image side surface of the sixth lens are convex surfaces, and the fifth lens and the sixth lens form a glue body; the seventh lens with positive focal power has a concave object-side surface and a convex image-side surface. The wide-angle lens has the advantages of miniaturization, super-large field angle and high resolution.

Description

Wide-angle lens and imaging apparatus

Technical Field

The invention relates to the technical field of imaging lenses, in particular to a wide-angle lens and imaging equipment.

Background

With the improvement of performance and the reduction of size of common photosensitive elements such as a photosensitive coupled device (CCD) and a Complementary Metal Oxide Semiconductor (CMOS), higher requirements are put forward for high imaging quality and miniaturization of a matched lens. The vehicle-mounted lens is also rapidly developed as a key component of an automatic driving assistance system, and the requirement for the lens is higher and higher. In some occasions, the imaging lens is required to have good thermal stability and wide-angle characteristic, and all glass materials with stable thermal expansion coefficients are used, so that the manufacturing cost is high, and the market competitiveness is poor; meanwhile, the existing wide-angle characteristics generally need to increase the number of lenses, are not beneficial to miniaturization, and also cause large aberration and poor imaging quality.

At present, plastic lenses are mostly adopted to achieve the effects of reducing cost and lightening weight, but the expansion with heat and contraction with cold of the plastic lenses is difficult to overcome. Of course, the imaging quality can be improved by adopting the glass aspheric lens, and the temperature performance requirement is met, but the glass aspheric lens is difficult to manufacture, the cost is high, the lens volume is often large, and the miniaturization and the light weight of the lens are not facilitated.

Disclosure of Invention

Therefore, the invention aims to provide a wide-angle lens and an imaging device, which have the advantages of miniaturization, super-large field angle and high resolution.

The embodiment of the invention implements the above object by the following technical scheme.

In a first aspect, the present invention provides a wide-angle lens, comprising, in order from an object side to an image plane along an optical axis: the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens having a positive optical power, an object side surface of the third lens being convex; the fourth lens is provided with positive focal power, and the object side surface and the image side surface of the fourth lens are convex surfaces; a diaphragm; a fifth lens element having a negative optical power, the fifth lens element having a concave object-side surface and a concave image-side surface; the fourth lens is provided with a fifth lens, a sixth lens with positive focal power, a fifth lens and a sixth lens, wherein the object side surface and the image side surface of the sixth lens are convex surfaces; the seventh lens with positive focal power, the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface; the first lens, the fifth lens and the sixth lens are all glass spherical lenses, the second lens, the third lens, the fourth lens and the seventh lens are all plastic aspheric lenses, and the optical centers of the lenses are all located on the same straight line.

In a second aspect, the present invention provides an imaging apparatus including an imaging element for converting an optical image formed by the wide-angle lens into an electric signal, and the wide-angle lens provided in the first aspect.

Compared with the prior art, the wide-angle lens and the imaging equipment provided by the invention adopt the matching of seven glass-plastic mixed lenses. The first lens adopts a glass lens with negative focal power, so that the distortion of the lens can be effectively reduced, and more light rays can be collected to enter the optical system, so that the light flux is increased; the second lens adopts a plastic aspheric lens with negative focal power, so that the aberration generated by the first lens can be effectively corrected, and the expansion of the high image field is facilitated; the third lens adopts a plastic aspheric lens with positive focal power, which is beneficial to the reasonable distribution of the positive and negative focal powers at the front end of the lens; the fourth lens adopts a plastic aspheric lens with positive focal power and is mainly used for correcting coma aberration and astigmatism; the fifth lens adopts a glass lens with negative focal power, the sixth lens adopts a glass lens with positive focal power, and the fifth lens can be glued with the sixth lens, so that the correction of chromatic aberration is facilitated; the seventh lens adopts a plastic aspheric lens with positive focal power, residual aberration can be effectively corrected, the resolving power of the lens is improved, and the first lens and the seventh lens adopt approximately symmetrical concentric circle structures, so that distortion can be effectively corrected. The wide-angle lens has the beneficial effects of miniaturization, super-large field angle, good processability and the like while realizing high imaging quality. In addition, the plastic lens effectively reduces the manufacturing cost and improves the product competitiveness; meanwhile, three glass lenses are adopted, so that the lens has good thermal stability, can keep good resolution in high and low temperature environments, and can meet the requirements of the fields of vehicle-mounted and the like.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic structural diagram of a wide-angle lens according to a first embodiment of the present invention;

FIG. 2 is a field curvature diagram of a wide-angle lens according to a first embodiment of the present invention;

FIG. 3 is an MTF chart of the wide-angle lens according to the first embodiment of the present invention;

FIG. 4 is a graph showing axial chromatic aberration of the wide-angle lens according to the first embodiment of the present invention;

fig. 5 is a schematic structural diagram of a wide-angle lens according to a second embodiment of the present invention;

FIG. 6 is a field curvature diagram of a wide-angle lens according to a second embodiment of the present invention;

FIG. 7 is an MTF chart of a wide-angle lens according to a second embodiment of the present invention;

FIG. 8 is a graph showing axial chromatic aberration of a wide-angle lens according to a second embodiment of the present invention;

fig. 9 is a schematic structural diagram of a wide-angle lens according to a third embodiment of the present invention;

fig. 10 is a field curvature graph of a wide-angle lens according to a third embodiment of the present invention;

fig. 11 is an MTF chart of a wide-angle lens according to a third embodiment of the present invention;

fig. 12 is a graph showing an axial chromatic aberration of a wide-angle lens according to a third embodiment of the present invention;

fig. 13 is a schematic configuration diagram of an image forming apparatus according to a fourth embodiment of the present invention.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Like reference numerals refer to like elements throughout the specification.

The invention provides a wide-angle lens, which sequentially comprises the following components from an object side to an imaging surface along an optical axis: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a diaphragm, a fifth lens, a sixth lens, a seventh lens and an optical filter.

The first lens has negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

the second lens has negative focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

the third lens has positive focal power, and the object side surface of the third lens is a convex surface;

the fourth lens has positive focal power, and both the object side surface and the image side surface of the fourth lens are convex surfaces;

the fifth lens has negative focal power, and the object side surface and the image side surface of the fifth lens are both concave surfaces;

the sixth lens has positive focal power, the object side surface and the image side surface of the sixth lens are convex surfaces, and meanwhile, the fifth lens and the sixth lens form a glue body;

the seventh lens has positive focal power, the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface.

The diaphragm is arranged between the fourth lens and the fifth lens; the optical filter is arranged between the seventh lens and the imaging surface and can be used for selectively filtering part of light so as to optimize the imaging result.

The first lens, the fifth lens and the sixth lens are all glass spherical lenses, the second lens, the third lens, the fourth lens and the seventh lens are all plastic aspheric lenses, and the optical centers of the lenses are all located on the same straight line.

Further, in some embodiments, the wide-angle lens satisfies the conditional expression:

0.13＜BFL/TTL＜0.19；（1）

the BFL represents a distance between an image side surface of the seventh lens element and the imaging surface on an optical axis (i.e., an optical back focal length), and the TTL represents an optical total length of the wide-angle lens. The condition formula (1) is satisfied, the back focal distance of the wide-angle lens can be reasonably controlled, and the installation and use of the lens are facilitated.

1.8＜Imgh/f ＜2.2；（2）

where Imgh denotes an image height corresponding to a maximum field angle of the wide-angle lens, and f denotes an effective focal length of the wide-angle lens. The imaging device satisfies the conditional expression (2), and can realize imaging of the photosensitive element to a larger object side space by controlling the ratio of the imaging range to the focal length, thereby being beneficial to wide angle.

0.021/°＜（DT11/Imgh）/HFOV＜0.023/°；（3）

DT11 denotes an effective radius of an object-side surface of the first lens, Imgh denotes an image height corresponding to a maximum field angle of the wide-angle lens, and HFOV denotes a maximum field angle of the wide-angle lens. Satisfying the conditional expression (3), by controlling the value of DT11, a small aperture at the front end of the lens can be realized.

-3.9＜f2/f＜-2.9；（4）

where f2 denotes an effective focal length of the second lens, and f denotes an effective focal length of the wide-angle lens. And the condition (4) is met, the deflection angle of light can be reduced by adjusting the effective focal length of the second lens, and the subsequent lens is favorably reduced in aberration.

4.1＜f7/f＜4.8；（5）

where f7 denotes an effective focal length of the seventh lens, and f denotes an effective focal length of the wide-angle lens. And the condition formula (5) is met, the emergent angle of the light can be controlled by adjusting the effective focal length of the seventh lens, and the optical back focal length of the lens can be increased.

0.06＜CT1/TTL＜0.08；（6）

where CT1 denotes the center thickness of the first lens, and TTL denotes the total optical length of the wide-angle lens. The condition (6) is satisfied, which is beneficial to the lens forming and ensures the stable yield of the product.

2.3＜ET5/CT5+ET6/CT6＜2.8；（7）

where ET5 denotes an edge thickness of the fifth lens, CT5 denotes a center thickness of the fifth lens, ET6 denotes an edge thickness of the sixth lens, and CT6 denotes a center thickness of the sixth lens. The condition (7) is met, the ratio of the center thickness to the edge thickness of the fifth lens and the sixth lens is reasonably configured, the manufacturing difficulty of the lens can be reduced, and the bonding yield of the glass lens is increased.

0.45＜ƩCT/TTL＜0.48；（8）

wherein Ʃ CT denotes a sum of central thicknesses of the first lens to the seventh lens, and TTL denotes an optical total length of the wide-angle lens. Satisfying the conditional expression (8), the total central thickness Ʃ CT of the lens can be reasonably configured, the optical total length of the lens can be effectively shortened, and the miniaturization and the wide angle of the lens can be realized.

0.15≤|Nd5-Nd6|≤0.16；（9）

30＜|Vd5-Vd6|＜32；（10）

where Nd5 denotes a refractive index of the fifth lens, Nd6 denotes a refractive index of the sixth lens, Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens. The conditional expressions (9) and (10) are met, the refractive index and dispersion relation between the fifth lens and the sixth lens is reasonably distributed and balanced, chromatic aberration of the system can be well corrected, and imaging quality is improved.

The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection of each lens in the wide-angle lens are different, and the specific differences can be referred to in the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.

In the embodiments of the present invention, when the lens in the wide-angle lens is an aspherical lens, the aspherical surface type of the lens satisfies the following equation:

wherein z represents the distance between the curved surface and the vertex of the curved surface in the optical axis direction, C represents the curvature of the vertex of the curved surface, K represents a conic coefficient, h represents the distance between the optical axis and the curved surface, and B, C, D, E, F, G, H represents the curved surface coefficients of fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order and sixteenth order, respectively.

Further, in some embodiments, the wide-angle lens has an f-number not greater than 2.1, which can meet the requirements of a dark environment.

First embodiment

Referring to fig. 1, a schematic structural diagram of a wide-angle lens 100 according to a first embodiment of the present invention is shown, where the wide-angle lens 100 sequentially includes, from an object side to an image plane along an optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a stop STO, a fifth lens L5, a sixth lens L6, a seventh lens L7, and a filter L8.

The first lens element L1 has negative power, the object-side surface S1 of the first lens element is convex, and the image-side surface S2 of the first lens element is concave;

the second lens L2 has negative focal power, the object-side surface S3 of the second lens is convex, and the image-side surface S4 of the second lens is concave;

the third lens L3 has positive optical power, the object-side surface S5 of the third lens is convex, and the image-side surface S6 of the third lens is convex at the paraxial region;

the fourth lens L4 has positive optical power, and both the object-side surface S7 and the image-side surface S8 of the fourth lens are convex;

the fifth lens L5 has negative power, and both the object-side surface S10 and the image-side surface of the fifth lens are concave;

the sixth lens element L6 has positive refractive power, the object-side surface and the image-side surface S12 of the sixth lens element are convex surfaces, and the fifth lens element L5 and the sixth lens element L6 form a cemented body whose bonding surface is S11.

The seventh lens L7 has positive power, and the object-side surface S13 of the seventh lens is concave, and the image-side surface S14 of the seventh lens is convex.

The first lens L1, the fifth lens L5 and the sixth lens L6 are all glass spherical lenses, the second lens L2, the third lens L3, the fourth lens L4 and the seventh lens L7 are all plastic aspheric lenses, and the optical centers of the lenses are all located on the same straight line.

Referring to tables 1, 2 and 3, the parameters of the wide-angle lens 100 according to the first embodiment of the present invention are shown:

TABLE 1

TABLE 2

TABLE 3

Referring to fig. 2, fig. 3 and fig. 4, a field curvature graph, an MTF graph and an axial chromatic aberration graph of the wide-angle lens 100 in the first embodiment are respectively shown. As can be seen from fig. 2, the field curvature of the meridional image plane and the sagittal image plane in the entire field of view is within ± 0.1mm as a whole, which indicates that the field curvature of the wide-angle lens 100 is well corrected. As can be seen from fig. 3, the overall MTF value is greater than 0.5 at 60 lp/mm, which indicates that the wide-angle lens 100 has good resolution performance. As can be seen from fig. 4, the total chromatic aberration is within ± 0.03mm, which indicates that the wide-angle lens 100 has high achromatic performance.

Second embodiment

Referring to fig. 5, a schematic structural diagram of a wide-angle lens 200 according to a second embodiment of the present invention is shown, where the structure of the wide-angle lens 200 according to the second embodiment of the present invention is substantially the same as that of the wide-angle lens 100 according to the first embodiment, and the difference is mainly that the curvature radius of each lens is selected differently.

Referring to tables 4, 5 and 6, parameters of the wide-angle lens 200 according to the second embodiment of the present invention are shown

TABLE 4

TABLE 5

TABLE 6

Referring to fig. 6, 7 and 8, a field curvature graph, an MTF graph and an axial chromatic aberration graph of the wide-angle lens 200 in the second embodiment are respectively shown. As can be seen from fig. 6, the field curvature of the meridional image plane and the sagittal image plane in the entire field of view is within ± 0.1mm as a whole, indicating that the field curvature of the wide-angle lens 200 is well corrected. As can be seen from fig. 7, the overall MTF value is greater than 0.5 at 60 lp/mm, which indicates that the wide-angle lens 200 has good resolution performance. As can be seen from fig. 8, the total chromatic aberration is within ± 0.04mm, indicating that wide-angle lens 200 has high achromatic performance.

Third embodiment

Referring to fig. 9, a schematic structural diagram of a wide-angle lens 300 according to a third embodiment of the present invention is shown, where the structure of the wide-angle lens 300 according to the third embodiment of the present invention is substantially the same as that of the wide-angle lens 100 according to the first embodiment, and the difference is mainly that the curvature radius of each lens is selected differently.

Referring to tables 7, 8 and 9, the parameters of the wide-angle lens 300 according to the third embodiment of the present invention are shown:

TABLE 7

TABLE 8

TABLE 9

Referring to fig. 10, 11 and 12, a field curvature graph, an MTF graph and an axial chromatic aberration graph of the wide-angle lens 300 in the third embodiment are respectively shown. As can be seen from fig. 10, the field curvature of the meridional image plane and the sagittal image plane in the entire field of view is within ± 0.04mm as a whole, indicating that the field curvature of the wide-angle lens 300 is well corrected. As can be seen from fig. 11, the overall MTF value is greater than 0.6 at 60 lp/mm, which indicates that the wide-angle lens 300 has good resolution performance. As can be seen from fig. 12, the total chromatic aberration is within ± 0.03mm, indicating that wide-angle lens 300 has high achromatic performance.

Table 10 shows the optical parameters corresponding to the above three embodiments, which mainly include the effective focal length F, F-number F/NO, maximum field angle HFOV, and total optical length TTL of the wide-angle lens, and the values corresponding to each of the foregoing conditional expressions.

Watch 10

In summary, the present invention employs seven lenses, and reasonably distributes the focal power, the surface shape, the central thickness of each lens, the on-axis distance between each lens, and the like of each lens, so that the lens has the beneficial effects of miniaturization, an ultra-large field angle, good processability, and the like while achieving good quality. In the wide-angle lens, the first lens, the fifth lens and the sixth lens are all glass spherical lenses, and the second lens, the third lens, the fourth lens and the seventh lens are all plastic aspheric lenses. The invention enables the aberration of the lens to be effectively corrected by optimally configuring the positive and negative refractive indexes of each lens, and overcomes the defect that the lens made of plastic materials is easy to cause focus drift in high and low temperature environments due to large expansion coefficient of the lens. The use of the plastic aspheric lens can effectively correct the aberration of the lens and improve the resolution of the whole lens group; meanwhile, the glass and the plastic material are combined for use, so that the manufacturing cost is effectively reduced, and the product competitiveness is improved.

Fourth embodiment

Referring to fig. 13, an imaging device 400 according to a fourth embodiment of the present invention is shown, where the imaging device 400 may include an imaging element 410 and a wide-angle lens (e.g., wide-angle lens 100) in any of the embodiments described above. The imaging element 410 may be a CMOS (Complementary Metal Oxide Semiconductor) image sensor, and may also be a CCD (Charge Coupled Device) image sensor.

The imaging device 400 may be a vehicle-mounted monitoring device, a security device, an AR/VR device, a smart phone, or any other electronic device equipped with the wide-angle lens.

The imaging apparatus 400 provided by the present embodiment includes the wide-angle lens 100, and since the wide-angle lens 100 has advantages of miniaturization, an ultra-large field angle, and high resolution, the imaging apparatus 400 having the wide-angle lens 100 also has advantages of miniaturization, an ultra-large field angle, and high resolution.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A wide-angle lens, comprising, in order from an object side to an imaging surface along an optical axis:

the lens comprises a first lens with negative focal power, a second lens and a third lens, wherein the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

the second lens with negative focal power is characterized in that the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

a third lens having a positive optical power, an object side surface of the third lens being convex;

the fourth lens is provided with positive focal power, and the object side surface and the image side surface of the fourth lens are convex surfaces;

a diaphragm;

a fifth lens element having a negative optical power, the fifth lens element having a concave object-side surface and a concave image-side surface;

the fourth lens is provided with a fifth lens, a sixth lens with positive focal power, a fifth lens and a sixth lens, wherein the object side surface and the image side surface of the sixth lens are convex surfaces;

the seventh lens with positive focal power, the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface;

2. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.13＜BFL/TTL＜0.19；

and BFL represents the distance between the image side surface of the seventh lens and the imaging surface on the optical axis, and TTL represents the total optical length of the wide-angle lens.

3. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

1.8＜Imgh/f ＜2.2；

where Imgh denotes an image height corresponding to a maximum field angle of the wide-angle lens, and f denotes an effective focal length of the wide-angle lens.

4. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.021/°＜（DT11/Imgh）/HFOV＜0.023/°；

DT11 denotes an effective radius of an object-side surface of the first lens, Imgh denotes an image height corresponding to a maximum angle of view of the wide-angle lens, and HFOV denotes a maximum angle of view of the wide-angle lens.

5. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

-3.9＜f2/f＜-2.9；

where f2 denotes an effective focal length of the second lens, and f denotes an effective focal length of the wide-angle lens.

6. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

4.1＜f7/f＜4.8；

where f7 denotes an effective focal length of the seventh lens, and f denotes an effective focal length of the wide-angle lens.

7. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.06＜CT1/TTL＜0.08；

wherein CT1 denotes a center thickness of the first lens, and TTL denotes an optical total length of the wide-angle lens.

8. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

2.3＜ET5/CT5+ET6/CT6＜2.8；

wherein ET5 denotes an edge thickness of the fifth lens, CT5 denotes a center thickness of the fifth lens, ET6 denotes an edge thickness of the sixth lens, and CT6 denotes a center thickness of the sixth lens.

9. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.45＜ƩCT/TTL＜0.48；

wherein Ʃ CT represents the total thickness of the centers of the first lens to the seventh lens, and TTL represents the total optical length of the wide-angle lens.

10. The wide-angle lens of claim 1, wherein the wide-angle lens satisfies the conditional expression:

0.15≤|Nd5-Nd6|≤0.16；

30＜|Vd5-Vd6|＜32；

wherein Nd5 denotes a refractive index of the fifth lens, Nd6 denotes a refractive index of the sixth lens, Vd5 denotes an abbe number of the fifth lens, and Vd6 denotes an abbe number of the sixth lens.

11. An imaging apparatus comprising the wide-angle lens according to any one of claims 1 to 10, and an imaging element for converting an optical image formed by the wide-angle lens into an electrical signal.