Imaging lens

Abstract

This invention relates to an imaging lens, comprising a first lens group (G1) with positive optical power, a stop, and a second lens group (G2) with positive optical power, arranged sequentially from the object side to the image side. The first lens group (G1) is a fixed group, and the second lens group (G2) is a focusing lens group movable along the optical axis. The first lens group (G1) includes at least three positive optical power lenses and two negative optical power lenses. The imaging lens of this invention can achieve the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

Description

Technical Field

[0001] This invention relates to the field of optical devices, and more particularly to an imaging lens. Background Technology

[0002] Machine vision refers to using machines to replace human eyes for measurement and judgment. The target being captured is converted into an image signal and transmitted to a dedicated image processing system to obtain the shape information of the target. Based on pixel distribution and information such as brightness and color, it is converted into a digital signal. The image system performs various operations on these signals to extract the features of the target, such as position, size, and appearance, and then outputs the results according to preset conditions to realize functions such as automatic recognition, judgment, and measurement.

[0003] Therefore, imaging systems used in machine vision have very high requirements for pixels, image uniformity, distortion, brightness, and color reproduction. However, currently available machine vision lenses have relatively low optical magnification, small image size, large distortion, uneven image clarity, and a small working object distance range. Although such machine vision lenses have a wide shooting range, their imaging is not delicate enough, the dynamic range is not high, and the color and contrast are not good enough.

[0004] As machine vision is used more and more widely, the requirements for machine vision imaging systems are becoming increasingly stringent. Currently, machine vision lenses on the market are increasingly unable to meet market demands, especially in high-precision and high-tech fields where high image quality is required, which are severely limited. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and provide an imaging lens with a large aperture, high resolution, low distortion, uniform image quality, wide working distance range, good color reproduction, and high contrast.

[0006] To achieve the above-mentioned objective of the present invention, the present invention provides an imaging lens, comprising a first lens group having positive optical power, an aperture stop, and a second lens group having positive optical power arranged sequentially from the object side to the image side, wherein the first lens group is a fixed group and the second lens group is a focusing lens group that can move along the optical axis.

[0007] The first lens group includes at least three positive power lenses and two negative power lenses.

[0008] According to one aspect of the invention, along the object-side to the side direction, the first lens in the first lens group is a positive power lens, and its surface near the object-side is convex.

[0009] According to one aspect of the invention, along the object-to-image direction, the second lens in the first lens group is a negative power lens and is a convex-concave lens.

[0010] According to one aspect of the invention, the first lens group includes at least one cemented doublet lens located in front of the aperture stop near the image plane.

[0011] According to one aspect of the invention, the second lens group includes at least two positive power lenses and one negative power lens.

[0012] According to one aspect of the invention, along the object-to-image direction, the first lens in the second lens group is a positive power lens, and its surface near the image side is convex.

[0013] According to one aspect of the invention, the second lens group includes at least one cemented doublet lens, which is located between the first lens in the second lens group and the image plane along the object-side to image-side direction.

[0014] According to one aspect of the invention, the focal length of the second lens group is f2, and the focal length of the imaging lens is f, satisfying: 1.0≤f2 / f≤2.1.

[0015] According to one aspect of the present invention, the focal length of the first lens group is f1 and the focal length of the second lens group is f2, satisfying: 0.05≤f2 / f1≤0.7.

[0016] According to one aspect of the invention, the Abbe number VD and refractive index ND of at least one positive power lens in the first lens satisfy: 10≤VD≤30, 1.8≤ND≤2.1.

[0017] According to one aspect of the invention, the Abbe number VD2 and refractive index ND2 of at least one lens in the second lens group satisfy: 50≤VD2≤100, 1.40≤ND2≤1.70.

[0018] According to one aspect of the invention, the optical system of the imaging lens has a total height of H and a focal length of f, satisfying 0.4 ≤ H / f ≤ 1.0.

[0019] In the imaging lens of the present invention, the first lens group serves as a fixed group, and its main function is to correct the aberrations and distortions of the optical system while reducing the tolerance sensitivity of the system. The second lens group serves as a focusing group, which can effectively improve the imaging quality at different object distances and ensure the uniformity of the image.

[0020] The imaging lens of the present invention includes at least three positive power lenses and two negative power lenses in the first lens group. This arrangement, through the combined use of positive and negative power lenses, is beneficial for correcting spherical aberration, astigmatism, and distortion within the first lens group G1, enabling the achievement of a large aperture, while also reducing tolerance sensitivity within the group.

[0021] The imaging lens of this invention includes at least two positive power lenses and one negative power lens in the second lens group. This arrangement, through the combination of positive and negative power, facilitates the correction of spherical aberration, astigmatism, and distortion within the second lens group. Correction of aberrations in the second lens group reduces the proportion of aberration correction burden on the first lens group G1, better reducing the tolerance sensitivity to the focusing group and comprehensively improving the imaging quality of the optical system.

[0022] In the imaging lens of the present invention, along the object-side to side-side direction, the first lens in the first lens group is a positive power lens, and its surface near the object side is convex. The second lens in the first lens group is a negative power lens, and is a convex-concave lens. This arrangement enables the imaging lens of the present invention to smoothly collect incident light, effectively reduce field curvature and astigmatism caused by incident light at a large field of view, and achieve a large aperture while maintaining low distortion.

[0023] The imaging lens of the present invention, in accordance with the above-described configuration, sets a cemented doublet lens in the first lens group and a cemented doublet lens in the second lens group, such that the cemented doublet lens in the first lens group and the cemented doublet lens in the second lens group form an improved Gaussian structure, which can effectively reduce the incident angle of light and thus reduce tolerance sensitivity, and can effectively correct distortion. At the same time, setting a lens with positive optical power behind the aperture improves the imaging quality of the optical system and ensures the uniformity of the image. Attached Figure Description

[0024] Figure 1 A schematic diagram illustrating the structure of an imaging lens according to Embodiment 1 of the present invention;

[0025] Figure 2 This diagram schematically illustrates the distortion at the optimal working object distance of the imaging lens according to Embodiment 1 of the present invention.

[0026] Figure 3 This illustration illustrates the magnification chromatic aberration at the optimal working distance of the imaging lens according to Embodiment 1 of the present invention.

[0027] Figure 4 This schematic diagram illustrates the positional chromatic aberration of the imaging lens during focusing at the optimal working object distance according to Embodiment 1 of the present invention.

[0028] Figure 5 This diagram schematically illustrates the MTF (Medium-Friction Transformer) plot of the imaging lens at the optimal working object distance for focusing according to Embodiment 1 of the present invention.

[0029] Figure 6 This schematic diagram illustrates the structure of an imaging lens according to Embodiment 2 of the present invention.

[0030] Figure 7 This diagram schematically illustrates the distortion at the optimal working object distance of the imaging lens according to Embodiment 2 of the present invention.

[0031] Figure 8 This schematically illustrates the magnification chromatic aberration when focusing at the optimal working distance of the imaging lens according to Embodiment 2 of the present invention.

[0032] Figure 9 This schematic diagram illustrates the positional chromatic aberration of the imaging lens during focusing at the optimal working object distance according to Embodiment 2 of the present invention.

[0033] Figure 10 This schematic diagram illustrates the MTF chart of the imaging lens at the optimal working object distance for focusing according to Embodiment 2 of the present invention.

[0034] Figure 11 This schematic diagram illustrates the structure of an imaging lens according to Embodiment 3 of the present invention.

[0035] Figure 12 This diagram schematically illustrates the distortion at the optimal working object distance of the imaging lens according to Embodiment 3 of the present invention.

[0036] Figure 13 This illustration illustrates the magnification chromatic aberration at the optimal working distance of the imaging lens according to Embodiment 3 of the present invention.

[0037] Figure 14 This schematic diagram illustrates the positional chromatic aberration when the imaging lens is focused at the optimal working object distance according to Embodiment 3 of the present invention.

[0038] Figure 15 This schematic diagram illustrates the MTF chart of the imaging lens at the optimal working object distance for focusing according to Embodiment 3 of the present invention.

[0039] Figure 16 This schematic diagram illustrates the structure of an imaging lens according to Embodiment 4 of the present invention.

[0040] Figure 17 This diagram schematically illustrates the distortion at the optimal working object distance of the imaging lens according to Embodiment 4 of the present invention.

[0041] Figure 18 This illustration illustrates the magnification chromatic aberration at the optimal working distance of the imaging lens according to Embodiment 4 of the present invention.

[0042] Figure 19 This schematic diagram illustrates the positional chromatic aberration when the imaging lens is focused at the optimal working object distance according to Embodiment 4 of the present invention.

[0043] Figure 20 This schematic diagram illustrates the MTF chart of the imaging lens at the optimal working object distance for focusing according to Embodiment 4 of the present invention.

[0044] Figure 21 This schematic diagram illustrates the structure of an imaging lens according to Embodiment 5 of the present invention.

[0045] Figure 22 This diagram schematically illustrates the distortion at the optimal working object distance of the imaging lens according to Embodiment 5 of the present invention.

[0046] Figure 23 This illustration illustrates the magnification chromatic aberration at the optimal working distance of the imaging lens according to Embodiment 5 of the present invention.

[0047] Figure 24 This schematic diagram illustrates the positional chromatic aberration of the imaging lens during focusing at the optimal working object distance according to Embodiment 5 of the present invention.

[0048] Figure 25 The diagram illustrates the MTF (Medium-Friction Transformer) at the optimal working object distance for focusing of the imaging lens according to Embodiment 5 of the present invention. Detailed Implementation

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0050] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0051] Reference Figure 1 As shown, this invention provides an imaging lens, comprising a first lens group G1 with positive optical power, an aperture stop (STOP), and a second lens group G2 with positive optical power, arranged sequentially from the object side to the image side. The first transparent group G1 is a fixed group, and the second lens group is an internal focusing lens group. When imaging from an object at infinity to a closer object, the second transparent group G2 moves along the optical axis. In this invention's imaging lens, the first lens group G1, as a fixed group, primarily functions to correct aberrations and distortions in the optical system while reducing the system's tolerance sensitivity. Using the second lens group G2 as a focusing group effectively improves image quality at different object distances and ensures image uniformity.

[0052] In this invention, the first lens group G1 includes at least three positive power lenses and two negative power lenses. This arrangement, through the combined use of positive and negative power lenses, helps to correct spherical aberration, astigmatism, and distortion within the first lens group G1, facilitates the achievement of a large aperture, and also reduces tolerance sensitivity within the group.

[0053] In this invention, the second lens group G2 includes at least two positive power lenses and one negative power lens. This arrangement, through the combination of positive and negative power, facilitates the correction of spherical aberration, astigmatism, and distortion within the second lens group G2. Correction of aberrations in the second lens group G2 reduces the proportion of aberration correction burden on the first lens group G1, better reducing the tolerance sensitivity to the focusing group and comprehensively improving the imaging quality of the optical system.

[0054] In this invention, along the object-side to side-side direction, the first lens in the first lens group G1 is a positive power lens, and its surface near the object side is convex. The second lens in the first lens group G1 is a negative power lens, and is a convex-concave lens. This configuration allows the imaging lens of this invention to smoothly collect incident light, effectively reducing field curvature and astigmatism caused by incident light at a large field of view, achieving a large aperture while maintaining low distortion.

[0055] In this invention, the first lens group G1 includes at least one cemented doublet lens located in front of the aperture stop near the image plane. In the imaging lens of this invention, from the object side to the image side, the first lens in the second lens group G2 is a positive power lens, and its surface near the image plane is convex. The second lens group G2 also includes at least one cemented doublet lens located between the first lens and the image plane.

[0056] The imaging lens of the present invention, in accordance with the above-described configuration, comprises a cemented doublet lens in the first lens group G1 and a cemented doublet lens in the second lens group G2, such that the cemented doublet lens in the first lens group G1 and the cemented doublet lens in the second lens group G2 form an improved Gaussian structure. This effectively reduces the incident angle of light, thereby reducing tolerance sensitivity, and also effectively corrects distortion. At the same time, the placement of a lens with positive optical power behind the aperture stop improves the imaging quality of the optical system and ensures the uniformity of the image.

[0057] In the imaging lens of this invention, the focal length of the second lens group G2 is f2, and the focal length of the imaging lens is f, satisfying: 1.0 ≤ f2 / f ≤ 2.1. Within this parameter range, it is beneficial to improve the focusing performance of the optical system and balance the tolerance sensitivity between the first lens group G1 and the second lens group G2. If the value is less than the lower limit of the relation, the optical power of the second lens group G2 is too large, which will lead to a large tolerance between the first and second lens groups. If the value is greater than the upper limit of the relation, the optical power of the second lens group is too small, which will lead to poor focusing performance, resulting in a larger focus formation and an increased length of the lens's optical system.

[0058] In the imaging lens of this invention, the focal length of the first lens group G1 is f1, and the focal length of the second lens group G2 is f2, satisfying: 0.05 ≤ f2 / f1 ≤ 0.7. Satisfying the above-mentioned relationship range balances the load ratio of the first lens group G1 and the second lens group G2 on the back focal length and CRA, which is beneficial for ensuring focusing performance and a smaller principal ray incident angle on the image plane, thus improving the imaging quality of the optical system.

[0059] In the imaging lens of the present invention, at least one positive power lens in the first lens group G1 has an Abbe number VD and a refractive index ND that satisfy: 10≤VD≤30, 1.8≤ND≤2.1. This setting can effectively reduce the aberrations of the optical system, while controlling the incident angle of light, reducing the sensitivity to tolerances, thereby improving the imaging quality of the optical system.

[0060] The imaging lens of this invention has an optical system with a total height of H and a focal length of f, satisfying 0.4 ≤ H / f ≤ 1.0. This configuration effectively controls the incident angle of light, reduces optical distortion, and improves the imaging quality of the optical system.

[0061] In summary, the imaging lens of the present invention, configured according to the above limitations, can achieve the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

[0062] The following five specific embodiments based on the above-described configuration of the present invention are given to specifically illustrate the imaging lens according to the present invention.

[0063] The data for the five implementation methods are shown in Table 1 below:

[0064] Conditional expression Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[1.0≤f2 / f≤2.1]]> 1.2125 1.7033 1.7515 1.1024 2.091 <![CDATA[0.05≤f2 / f1≤0.7]]> 0.5397 0.2400 0.05 0.0928 0.6909 0.4 ≤ H / f ≤ 1.0 0.750 0.796 0.487 0.416 0.994

[0065] Table 1

[0066] Implementation Method 1:

[0067] Figure 1 This is a schematic diagram illustrating the imaging lens structure according to Embodiment 1 of the present invention.

[0068] In Implementation Method 1, the total length of the optical system is TTL = 48.581 mm, the system focal length is f = 13.5 mm, and the F-number is FNO = 1.4.

[0069] Table 2 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0070]

[0071]

[0072] Table 2

[0073] Combination Figure 1 As shown, in this embodiment, the first lens group G1 includes six lenses (L1-L6), of which lenses L5 and L6 form a cemented doublet. The second lens group G2 includes four lenses (L7-L10), of which lenses L8 and L9 are cemented doublets. The refractive index ND and Abbe number VD of the fourth lens in the first lens group G1 are 1.90 and 23.5, respectively. The refractive index ND2 and Abbe number VD2 of the third lens in the second lens group G2 are 1.50 and 84.9, respectively.

[0074] Figure 2-5 The diagrams schematically illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF diagrams of the imaging lens according to Embodiment 1 of the present invention during optimal working distance focusing. Referring to the accompanying drawings, it can be seen that the imaging lens obtained according to Embodiment 1 of the present invention achieves the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working distance range, good color reproduction, and high contrast.

[0075] Implementation Method Two:

[0076] Figure 6 This is a schematic diagram illustrating the imaging lens structure according to Embodiment 2 of the present invention.

[0077] In Implementation Method 2, the total length of the optical system is TTL = 45.08 mm, the system focal length is f = 14 mm, and the F number is FNO = 2.0.

[0078] Table 3 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0079]

[0080]

[0081] Table 3

[0082] Combination Figure 6 As shown, in this embodiment, the first lens group G1 includes five lenses (L1-L5), of which lenses L4 and L5 are cemented doublets. The second lens group G2 includes four lenses (L6-L9), of which lenses L7 and L8 are cemented doublets. The refractive index ND and Abbe number VD of the third lens in the first lens group G1 are 1.98 and 16.5, respectively. The refractive index ND2 and Abbe number VD2 of the third lens in the second lens group G2 are 1.46 and 90.0, respectively.

[0083] Figure 7-10The accompanying drawings schematically illustrate the distortion diagram, magnification chromatic aberration diagram, positional chromatic aberration diagram, and MTF diagram of the imaging lens according to Embodiment 2 of the present invention during optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the imaging lens obtained according to Embodiment 2 of the present invention achieves the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

[0084] Implementation Method 3:

[0085] Figure 11 This is a schematic diagram illustrating the imaging lens structure according to Embodiment 3 of the present invention.

[0086] In Implementation Method 3, the total length of the optical system is TTL = 53.565 mm, the system focal length is f = 18.49 mm, and the F-number is FNO = 1.8.

[0087] Table 4 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0088]

[0089]

[0090] Table 4

[0091] Combination Figure 11 As shown, in this embodiment, the first lens group G1 includes six lenses (L1-L6), of which lenses L5 and L6 form a cemented doublet. The second lens group G2 includes four lenses (L7-L10), of which lenses L8 and L9 are cemented doublets. The refractive index ND and Abbe number VD of the fourth lens in the first lens group G1 are 1.85 and 24.2, respectively. The refractive index ND2 and Abbe number VD2 of the third lens in the second lens group G2 are 1.48 and 64.7, respectively.

[0092] Figure 12-15 The diagrams schematically illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF diagrams of the imaging lens according to Embodiment 3 of the present invention during optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the imaging lens obtained according to Embodiment 3 of the present invention achieves the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

[0093] Implementation Method Four:

[0094] Figure 16 This is a schematic diagram illustrating the imaging lens structure according to Embodiment 4 of the present invention.

[0095] In Implementation Method 4, the total length of the optical system is TTL = 50.471 mm, the system focal length is f = 13.00 mm, and the F-number is FNO = 1.5.

[0096] Table 5 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0097]

[0098]

[0099] Table 5

[0100] Combination Figure 16 As shown, in this embodiment, the first lens group G1 includes six lenses (L1-L6), wherein lenses L5 and L6 form a cemented doublet. The second lens group G2 includes four lenses (L7-L10), wherein lenses L8 and L9 are cemented doublets. The refractive index ND and Abbe number VD of the fourth lens in the first lens group G1 are 1.86 and 24.6, respectively. The refractive index ND2 and Abbe number VD2 of the third lens in the second lens group G2 are 1.59 and 79.3, respectively.

[0101] Figure 17-20 The diagrams schematically illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF diagrams of the imaging lens according to Embodiment 4 of the present invention during optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the imaging lens obtained according to Embodiment 4 of the present invention achieves the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

[0102] Implementation Method 5:

[0103] Figure 21 This is a schematic diagram illustrating the imaging lens structure according to Embodiment 5 of the present invention.

[0104] In Implementation Method 5, the total length of the optical system is TTL = 43.82 mm, the system focal length is f = 12.00 mm, and the F-number is FNO = 1.6.

[0105] Table 6 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0106]

[0107]

[0108] Table 6

[0109] Combination Figure 21As shown, in this embodiment, the first lens group G1 includes six lenses (L1-L6), of which lenses L5 and L6 form a cemented doublet. The second lens group G2 includes three lenses (L7-L9), of which lenses L8 and L9 are cemented doublets. The refractive index ND and Abbe number VD of the fourth lens in the first lens group G1 are 1.84 and 23.7, respectively. The refractive index ND2 and Abbe number VD2 of the third lens in the second lens group G2 are 1.59 and 71.2, respectively.

[0110] Figure 21-25 The diagrams schematically illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF diagrams of the imaging lens according to Embodiment 5 of the present invention during optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the imaging lens obtained according to Embodiment 5 of the present invention achieves the characteristics of large aperture, high resolution, low distortion, uniform image quality, wide working object distance range, good color reproduction, and high contrast.

[0111] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An imaging lens, characterized in that, It includes a first lens group (G1) with positive optical power, an aperture stop (STOP), and a second lens group (G2) with positive optical power arranged sequentially from the object side to the image side, for a total of two lens groups. The first lens group (G1) is a fixed group, and the second lens group (G2) is a focusing lens group that can move along the optical axis. The second lens group (G2) consists of four lenses with optical power, arranged in the following order: positive optical power, negative optical power, positive optical power, positive optical power. The first lens group (G1) consists of five or six lenses with optical power. When the first lens group (G1) consists of six lenses with optical power, the arrangement of optical power is: positive optical power, negative optical power, negative optical power, positive optical power, positive optical power, negative optical power, or... Positive power, negative power, positive power, negative power, positive power, negative power; When the first lens group (G1) consists of five lenses with optical power, the arrangement of optical power is: positive optical power, negative optical power, positive optical power, positive optical power, negative optical power; or The second lens group (G2) consists of three lenses with optical power, arranged in the following order: positive optical power, negative optical power, positive optical power; the first lens group (G1) consists of six lenses with optical power, arranged in the following order: positive optical power, negative optical power, positive optical power, negative optical power, positive optical power, negative optical power.

2. The imaging lens according to claim 1, characterized in that, Along the object-side to the side direction, the first lens in the first lens group (G1) is a positive power lens, and its surface near the object-side is convex.

3. The imaging lens according to claim 2, characterized in that, Along the object-to-image direction, the second lens in the first lens group (G1) is a negative power lens and is a convex-concave lens.

4. The imaging lens according to claim 1, characterized in that, The last two lenses in the first lens group (G1) form a cemented doublet lens, which is located in front of the aperture near the image plane.

5. The imaging lens according to claim 1, characterized in that, Along the object-to-image direction, the first lens in the second lens group (G2) is a positive power lens, and its surface near the image side is convex.

6. The imaging lens according to claim 1, characterized in that, The second and third lenses in the second lens group (G2) form a cemented doublet lens, which is located between the first lens in the second lens group (G2) and the image plane along the object-to-image direction.

7. The imaging lens according to claim 1 or 6, characterized in that, The focal length of the second lens group (G2) is f2, and the focal length of the imaging lens is f, satisfying: 1.0≤f2 / f≤2.

1.

8. The imaging lens according to claim 1 or 6, characterized in that, The focal length of the first lens group (G1) is f1, and the focal length of the second lens group (G2) is f2, satisfying: 0.05≤f2 / f1≤0.

7.

9. The imaging lens according to claim 1, characterized in that, The Abbe number VD and refractive index ND of at least one positive power lens in the first lens group (G1) satisfy: 10≤VD≤30, 1.8≤ND≤2.

1.

10. The imaging lens according to claim 1, characterized in that, The Abbe number VD2 and refractive index ND2 of at least one lens in the second lens group (G2) satisfy: 50≤VD2≤100, 1.40≤ND2≤1.

70.

11. The imaging lens according to claim 1, characterized in that, The optical system of the imaging lens has a total height of H and a focal length of f, satisfying 0.4≤H / f≤1.0.

Images