A wide-angle large-aperture long flange video lens with a focal length of 24mm

Abstract

The present invention relates to a wide-angle large-aperture long flange video lens with a focal length of 24 mm, which includes a first lens group and a second lens group arranged in sequence along the light incident direction of the optical path, and also includes a variable aperture, and the variable aperture is arranged in the second lens group; the first lens group, as a fixed group, has a positive optical power, and the first lens group is composed of lenses L11 to L18 arranged in sequence along the light incident direction of the optical path; the second lens group, as a focusing group, has a positive optical power, and the second lens group is composed of lenses L21 to L28 arranged in sequence along the light incident direction of the optical path; moreover, the first lens group and the second lens group satisfy 0.36 < f2 / f1 < 0.44, where f1 represents the focal length value of the first lens group and f2 represents the focal length value of the second lens group; thus, the lens has the advantages of high resolution, large aperture, small distortion and small chromatic aberration.

Description

Technical Field

[0001] The present invention belongs to the technical field of photographic lenses, and particularly relates to a wide-angle large-aperture long flange video lens with a focal length of 24 mm. Background Art

[0002] With the rapid development of social economy, people's demand for film shooting is increasing day by day, the demand for video shooting scenes is increasing, and thus the index parameters of video lenses are constantly improved. Among them, the important indicators for short-focus video lenses are high definition, large aperture, good chromatic aberration effect and small distortion.

[0003] However, the applicant has found that: the short-focus video lenses currently on the market generally have the disadvantages of insufficient resolution, excessive distortion, small aperture, too long optical total length and too short flange back focal length, etc., and simply cannot meet the high requirements of the film shooting field of view, especially for short-focus video lenses with a focal length of 24 mm. Summary of the Invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a wide-angle large-aperture long flange video lens with a focal length of 24 mm.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a wide-angle large-aperture long flange video lens with a focal length of 24 mm. The lens includes a first lens group and a second lens group arranged in sequence along the light incident direction of the light path, and also includes a variable aperture. The variable aperture is arranged in the second lens group; wherein,

[0007] The first lens group, as a fixed group, has a positive optical power, and the first lens group is composed of lenses L11 to L18 arranged in sequence along the light incident direction of the light path;

[0008] The second lens group, as a focusing group, has a positive optical power, and the second lens group is composed of lenses L21 to L28 arranged in sequence along the light incident direction of the light path;

[0009] Moreover, the first lens group and the second lens group satisfy the following formula:

[0010] 0.36 < f2 / f1 < 0.44

[0011] Wherein, f1 represents the focal length value of the first lens group, and f2 represents the focal length value of the second lens group.

[0012] Furthermore, the variable aperture is arranged between lens L22 and lens L23.

[0013] Further, the optical system contains two glass aspherical lenses, namely lens L13 of the first lens group and lens L28 of the second lens group.

[0014] Further, the coefficients of the object side of lens L13 are: K = -2.876523952, E4 = 0.000010495986460430, E6 = -0.000000028363851874, E8 = 0.000000000071898491, E10 = -0.000000000000051943, R1 = 94.218758243;

[0015] The coefficients of the image side of lens L13 are: K = -1.008655314, E4 = 0.000005799440018926, E6 = -0.000000031003395997, E8 = -0.000000000123571109, E10 = 0.000000000000751939, E12 = -0.000000000000001723, R2 = 21.587115529;

[0016] The coefficients of the object side of lens L28 of the second lens group are: K = 0.000000000, E4 = -0.000014121315777320, E6 = -0.000000030601349490, E8 = 0.000000000097245102, E10 = -0.000000000000442273, E12 = 0.000000000000000767, R1 = -83.509908631;

[0017] The coefficients of the image side of lens L28 are: K = 0.000000000, E4 = -0.000008755901152306, E6 = -0.000000026955244583, E8 = 0.000000000082106050, E10 = -0.000000000000296455, E12 = 0.000000000000000438, R2 = -51.501175972.

[0018] Further, the optical system composed of the first lens group and the second lens group contains three groups of doublet lenses and one group of triplet lenses.

[0019] Furthermore, the lens L14 and the lens L15 of the first lens group form a first group of doublet lenses, the lens L16 and the lens L17 form a second group of doublet lenses, the lens L21 and the lens L22 of the second lens group form a third group of doublet lenses, and the lenses L23 to L25 of the second lens group form a group of triplet lenses.

[0020] Furthermore, at least three lenses of the first lens group have a refractive index greater than 1.65 and less than 1.75, and at least two lenses of the second lens group have a refractive index greater than 1.45 and less than 1.55.

[0021] Furthermore, at least two lenses of the first lens group have an Abbe number greater than 18 and less than 28, and at least two lenses of the second lens group have an Abbe number greater than 77 and less than 83.

[0022] Furthermore, the total length of the optical system formed by the first lens group and the second lens group is greater than 157 mm and less than 163 mm. The focal length adjustment range of the optical system is 23.48 mm to 23.81 mm. Moreover, during the adjustment process of the focal length adjustment range, the adjustment range of the aperture is 1.36 mm to 1.30 mm, the adjustment range of the half field angle is 42.603° to 42.641°, the adjustment range of the object distance is 141 mm to infinity, the distance adjustment range between the image side of the lens L18 and the object side of the lens L21 is 2.186779 mm to 5.5003 mm, and the adjustment range of the back focal length is 40.324315 mm to 37.010793 mm.

[0023] Furthermore, the structure of the optical system formed by the first lens group and the second lens group is specifically as follows in the table:

[0024] 。

[0025] Advantages of the present invention:

[0026] 1. By optimizing the combination of 14 standard spherical lenses and 2 aspherical lenses, the present invention obtains a short-focus 24 mm cine lens that can optimize small distortion and good chromatic aberration while meeting the requirements of optimizing high resolution and large aperture.

[0027] 2. By adopting a compact optical structure to optimize the total optical length, the total length of the optical system formed by the first lens group G1 and the second lens group G2 is greater than 157 mm and less than 163 mm, reducing the total optical length; at the same time, it can also meet the requirements of a camera module with a relatively long flange back focal length. Description of the Drawings

[0028] Figure 1It is a schematic structural diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention;

[0029] Figure 2 It is a relative illumination curve diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to an embodiment of the present invention;

[0030] Figure 3 It is a lateral chromatic aberration diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to an embodiment of the present invention;

[0031] Figure 4 It is a field curvature and distortion diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to an embodiment of the present invention;

[0032] Figure 5 It is an MTF curve diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to an embodiment of the present invention;

[0033] Figure 6 It is an MTF defocus curve diagram of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to an embodiment of the present invention;

[0034] Figure 7 It is a lateral chromatic aberration diagram of the video lens tested in Comparative Example 1 of the present invention;

[0035] Figure 8 It is a field curvature and distortion diagram of the video lens tested in Comparative Example 1 of the present invention;

[0036] Figure 9 It is an MTF curve diagram of the video lens tested in Comparative Example 1 of the present invention;

[0037] Figure 10 It is a lateral chromatic aberration diagram of the video lens tested in Comparative Example 2 of the present invention;

[0038] Figure 11 It is a field curvature and distortion diagram of the video lens tested in Comparative Example 2 of the present invention;

[0039] Figure 12 It is an MTF curve diagram of the video lens tested in Comparative Example 2 of the present invention. Detailed implementation manners

[0040] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] As Figure 1As shown, in the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention, a first lens group G1 and a second lens group G2 are sequentially provided along the light incident direction of the optical path. Among them,

[0042] The first lens group G1, as a fixed group, has a positive optical power. The first lens group G1 is composed of lenses L11 to L18 sequentially arranged along the light incident direction of the optical path; the second lens group G2, as a focusing group, has a positive optical power. The second lens group G2 is composed of lenses L21 to L28 sequentially arranged along the light incident direction of the optical path; among the optical system composed of the first lens group G1 and the second lens group G2, there are two glass aspherical lenses, which are the third lens and the sixteenth lens counted from the light incident direction of the lens optical path (i.e., lens L13 of the first lens group and lens L28 of the second lens group), and the remaining 14 lenses are all standard spherical lenses; the structural parameters of the two glass aspherical lenses are specifically as shown in Table 1 below:

[0043] Table 1

[0044]

[0045] In the table, K is the conic constant, E4, E6, E8, E10, and E12 are all aspherical machining coefficients, and R1 and R2 are the curvature radii.

[0046] Moreover, the first lens group G1 and the second lens group G2 satisfy the following formula:

[0047] 0.36 < f2 / f1 < 0.44

[0048] In the formula, f1 represents the focal length value of the first lens group G1, and f2 represents the focal length value of the second lens group G2; this formula represents the corresponding relationship between the optical powers of the first lens group G1 and the second lens group G2. If this formula is not satisfied, it will lead to the attenuation of optical performance such as MTF, chromatic aberration, and optical distortion.

[0049] Again, Figure 1 As shown, the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention further includes a variable aperture S, and the variable aperture S is arranged inside the second lens group G2. Specifically, the variable aperture S is arranged between lens L22 and lens L23.

[0050] When the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention works, the first lens group G1 remains stationary when the object moves from infinity to a short distance, and the second lens group G2 moves towards the object when the object moves from infinity to a short distance to achieve focusing.

[0051] Through experimental tests, the total length of the optical system of the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention composed of the above-mentioned first lens group G1 and second lens group G2 is greater than 157 mm and less than 163 mm, meeting the requirements of a camera module 100 with a relatively long flange back focus. The focal length adjustment range of the optical system is 23.48 mm to 23.81 mm. Moreover, during the adjustment process of the focal length adjustment range, its aperture is adjusted in the range of 1.36 mm to 1.30 mm, the half field angle is adjusted in the range of 42.603° to 42.641°, the object distance is adjusted in the range of 141 mm to infinity, the distance between the image side of lens L18 and the object side of lens L21 is adjusted in the range of 2.186779 mm to 5.5003 mm, and the back focus is adjusted in the range of 40.324315 mm to 37.010793 mm.

[0052] By adopting an optimized combination of 14G2GM (14 standard spherical lenses and 2 aspherical lenses), the present invention can obtain a short-focus 24 mm cine lens, and this lens can optimize small distortion and good chromatic aberration while meeting the requirements of optimized high resolution and large aperture. Specifically, by making the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2 satisfy 0.36 < f2 / f1 < 0.44, during the focusing process by moving the second lens group G2, high resolution and large aperture can be achieved while reducing the distortion and chromatic aberration generated during focusing.

[0053] In addition, the present invention also optimizes the total optical length by adopting a compact optical structure, making the total length of the optical system composed of the first lens group G1 and the second lens group G2 greater than 157 mm and less than 163 mm, reducing the total optical length; at the same time, it can also meet the requirements of a camera module 100 with a relatively long flange back focus.

[0054] In a possible implementation scheme, at least three lenses of the first lens group G1 have a refractive index greater than 1.65 and less than 1.75, at least two lenses of the second lens group G2 have a refractive index greater than 1.45 and less than 1.55, at least two lenses of the first lens group G1 have an Abbe number greater than 18 and less than 28, at least two lenses of the second lens group G2 have an Abbe number greater than 77 and less than 83, and the optical system composed of the first lens group G1 and the second lens group G2 includes three doublet lenses and one triplet lens.

[0055] The following further illustrates the wide-angle large-aperture long flange video lens with a focal length of 24 mm according to the present invention through examples and comparative examples. Example

[0056] The video lens in the embodiment of the present invention includes as Figure 1The first lens group G1, the second lens group G2, and the variable aperture S shown, where the variable aperture S is disposed within the second lens group G2. The structures of the first lens group G1 and the second lens group G2 are as described above and will not be repeated here. Among them, in this embodiment, the ratio of the focal length value f1 of the first lens group G1 to the focal length value f2 of the second lens group G2 is: f2 / f1 = 0.397; the structure of the optical system composed of the first lens group G1 and the second lens group G2 is specifically as shown in Table 2 below.

[0057] Table 2

[0058]

[0059] The overall specifications of the optical system composed of the first lens group G1 and the second lens group G2 in the embodiment of the present invention are as shown in Table 3 below.

[0060] Table 3

[0061]

[0062] When the object moves from infinity to a close distance, in this embodiment, the first lens group G1 remains stationary, and the second lens group G2 moves towards the object to achieve focusing, and it has high resolution (see Figure 5 and Figure 6 ), a large aperture (see Figure 2 , this figure is the relative illuminance curve graph of the video lens in the embodiment of the present invention for testing a light source with a wavelength of 0.546000 μm ), small distortion (see Figure 4 , this figure is the field curvature distortion graph of the video lens in the embodiment of the present invention for testing light sources with wavelengths of 0.435μm, 0.486μm, 0.546μm, 0.587μm, and 0.656μm at a maximum field of view of 21.500 mm), and small chromatic aberration (see Figure 3 , this figure is the lateral chromatic aberration graph of the video lens in the embodiment of the present invention for testing a light source with a wavelength of 0.546000μm at a maximum field of view of 21.5000 mm). Comparative Example 1

[0063] This Comparative Example 1 is basically the same as the video lens in the embodiment, including the first lens group G1, the variable aperture S, and the second lens group G2. The difference is that in this Comparative Example 1, the ratio of the focal length value f1 of the first lens group G1 to the focal length value f2 of the second lens group G2 is: f2 / f1 = 0.36, where f1 represents the focal length value of the first lens group G1 and f2 represents the focal length value of the second lens group G2, and the structure of the optical system composed of the first lens group G1 and the second lens group G2 is specifically as shown in Table 4 below.

[0064] Table 4

[0065]

[0066] Among them, the structural parameters of two pieces of glass aspherical lenses (lens L13 and lens L28) are specifically as shown in Table 5 below.

[0067] Table 5

[0068]

[0069] The same method as in the embodiment is adopted for testing. From the comparison between the test results of Comparative Example 1 ( Figures 7 - 9 ), it is found that in the optical performance of the lens of Comparative Example 1, the lateral chromatic aberration becomes larger, the MTF resolution decreases, and the optical distortion becomes larger. Comparative Example 2

[0070] This Comparative Example 2 is basically the same as the video lens described in the embodiment, including a first lens group G1, a variable aperture S, and a second lens group G2. The difference is that in this Comparative Example 2, the ratio of the focal length value f1 of the first lens group G1 to the focal length value f2 of the second lens group G2 is: f2 / f1 = 0.44, where f1 represents the focal length value of the first lens group G1, f2 represents the focal length value of the second lens group G2, and the structure of the optical system composed of the first lens group G1 and the second lens group G2 is specifically as shown in Table 6 below.

[0071] Table 6

[0072]

[0073] Among them, the structural parameters of two pieces of glass aspherical lenses (lens L13 and lens L28) are specifically as shown in Table 7 below.

[0074] Table 7

[0075]

[0076] The same method as in the embodiment is adopted for testing. From the comparison between the test results of Comparative Example 2 ( Figures 10 - 12 ), it is found that the lens of Comparative Example 2, like that of Comparative Example 1, has an increase in lateral chromatic aberration, a decrease in MTF resolution, and a large optical distortion in optical performance.

[0077] Therefore, from the above embodiments and Comparative Examples 1 and 2, it can be seen that if the focal length value f1 of the first lens group and the focal length value f2 of the second lens group of the lens according to the present invention do not satisfy 0.36 < f2 / f1 < 0.44, it will lead to defects such as attenuation of optical performance such as MTF, chromatic aberration, and optical distortion.

[0078] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm, characterized in that: The lens has two lens groups, including a first lens group and a second lens group arranged in sequence along the incident direction of the light path, and also includes a variable iris, which is arranged in the second lens group; wherein, The first lens group is a fixed group with positive focal power. The first lens group is composed of lenses L11 to L18 arranged in sequence along the incident direction of light along the optical path; wherein the lens L14 and the lens L15 constitute a first group of double-cemented lenses, and the lens L16 and the lens L17 constitute a second group of double-cemented lenses; the focal power of the lens L11, the lens L13, the lens L14 and the lens L17 is negative, and the focal power of the lens L12, the lens L15, the lens L16 and the lens L18 is positive; The second lens group, as a focusing group, has a positive focal power, and is composed of lenses L21 to L28 arranged in sequence along the incident direction of the light path; wherein the lens L21 and the lens L22 constitute a third group of doublets, and the lenses L23 to L25 of the second lens group constitute a group of triplets; the focal powers of the lenses L21, L24 and L26 are negative, and the focal powers of the lenses L22, L23, L25, L27 and L28 are positive; And the first lens group and the second lens group satisfy the following formula: 0.36 <f2 / f1<0.44 Wherein, f1 represents the focal length of the first lens group, and f2 represents the focal length of the second lens group; The optical system composed of the first lens group and the second lens group contains two glass aspherical lenses, namely lens L13 of the first lens group and lens L28 of the second lens group; The object side coefficients of the lens L13 are: K=-2.876523952, E4=0.000010495986460430, E6=-0.000000028363851874, E8=0.000000000071898491, E10=-0.0000000000000051943, R1=94.218758243mm; The image side coefficients of the lens L13 are: K=-1.008655314, E4=0.000005799440018926, E6=-0.0000000031003395997, E8=-0.0000000000123571109, E10=0.000000000000751939, E12=-0.0000000000000001723, R2=21.587115529mm; The object side coefficients of the lens L28 of the second lens group are: K=0.000000000, E4=-0.000014121315777320, E6=-0.000000030601349490, E8=0.0000000000097245102, E10=-0.000000000000442273, E12=0.000000000000000767, R1=-83.509908631 mm; The image side coefficients of the lens L28 are: K=0.000000000, E4=-0.000008755901152306, E6=-0.000000026955244583, E8=0.0000000000082106050, E10=-0.0000000000000296455, E12=0.000000000000000438, R2=-51.501175972mm.

2. The wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm according to claim 1, characterized in that: The variable aperture is disposed between the lens L22 and the lens L23.

3. The wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm according to claim 1 or 2, characterized in that: The refractive index of at least three lenses in the first lens group is greater than 1.65 and less than 1.75, and the refractive index of at least two lenses in the second lens group is greater than 1.45 and less than 1.

55.

4. The wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm according to claim 3, characterized in that: At least two lenses in the first lens group have an Abbe number greater than 18 and less than 28, and at least two lenses in the second lens group have an Abbe number greater than 77 and less than 83.

5. The wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm according to claim 1, 2 or 4, characterized in that: The total length of the optical system composed of the first lens group and the second lens group is greater than 157 mm and less than 163 mm. The focal length adjustment range of the optical system is 23.48 mm to 23.81 mm. In the process of adjusting the focal length adjustment range, the adjustment range of the aperture is 1.36 mm to 1.30 mm, the adjustment range of the half field angle is 42.603° to 42.641°, the adjustment range of the object distance is 141 mm to infinity, the adjustment range of the distance between the image side surface of lens L18 and the object side surface of lens L21 is 2.186779 mm to 5.5003 mm, and the adjustment range of the back focus is 40.324315 mm to 37.010793 mm.

6. The wide-angle, large-aperture, long-flange video lens with a focal length of 24 mm according to claim 5, characterized in that: The structure of the optical system composed of the first lens group and the second lens group is specifically shown in the following table: 。

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