Photographic wide-angle optical lens

Abstract

The invention discloses a photographing wide-angle optical lens, which relates to the technical field of optical lenses and comprises a first lens group with negative focal power, a second lens group with positive focal power and a third lens group with positive focal power which are sequentially arranged from an object side to an image side along an optical axis, the first lens group at least comprises an aspherical lens; an aperture diaphragm is arranged between the second lens group and the third lens group; the first lens group, the second lens group and the third lens group respectively satisfy the following conditional expressions:-3.0 < = F1 / F < =-0.8, 2.0 < = F2 / F < = 4.0, 2.5 < = F3 / F < = 4.0, F1 being the lens group focal length of the first lens group; f2 is the lens group focal length of the second lens group; f3 is the lens group focal length of the third lens group; f is the focal length of the photographing wide-angle optical lens. The photographing wide-angle optical lens is relatively short in focal length, small in size, higher in resolution and higher in focusing speed.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a wide-angle optical lens for photography. Background Art

[0002] Some existing wide-angle optical lenses for photography have a lens group structure with a small field of view, and the front lens has a large aperture, which makes the product bulky and inconvenient to carry.

[0003] As for another lens group structure, the focusing lens group of the lens contains multiple lenses. The focusing lens group with multiple lenses is heavier, which will affect the moving speed of the focusing lens group during focusing, that is, affect the focusing speed, and there may be noise during focusing. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a wide-angle optical lens for photography, which has a relatively short focal length, a small volume, a higher resolution, and a faster focusing speed.

[0005] A wide-angle optical lens for photography according to an embodiment of the present invention comprises a first lens group, a second lens group and a third lens group arranged in sequence from the object side to the image side along the optical axis; The first lens group has negative optical power, and the first lens group includes at least one aspherical lens; The second lens group has positive optical power; The third lens group has positive optical power; An aperture stop is provided between the second lens group and the third lens group; The first lens group, the second lens group and the third lens group respectively satisfy the following conditional expressions: -3.0≤F1 / F≤-0.8, 2.0≤F2 / F≤4.0, 2.5≤F3 / F≤4.0, in, F1: focal length of the first lens group; F2: focal length of the second lens group; F3: focal length of the third lens group; F: is the focal length of the wide-angle optical lens for photography.

[0006] The photographic wide-angle optical lens according to the embodiment of the present invention has at least the following beneficial effects: the photographic wide-angle optical lens that meets the conditional formula has a relatively short focal length, a small size, and a higher resolution; the first lens group meets the conditional formula, which can reduce the aperture of the first lens group, further miniaturize its size, and reduce the spherical aberration correction burden of the third lens group, and at the same time, the refractive power of the first lens group is moderate, and the off-axis aberration is easy to balance and correct; the second lens group meets the conditional formula, has a suitable refractive power and focusing stroke, and reduces the burden of the rear group on balancing aberrations; the third lens group meets the conditional formula, which can reduce the burden of the aspherical lens on balancing and correcting off-axis aberrations, making the surface shape of the aspherical lens simpler and easier to process, while achieving high-performance resolution.

[0007] According to some embodiments of the present invention, the first lens group includes 5 lenses.

[0008] According to some embodiments of the present invention, from the object side to the image side, the first lens group sequentially includes a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power and a fifth lens with negative optical power.

[0009] According to some embodiments of the present invention, at least one aspherical lens having negative optical power is included in the aspherical lenses included in the first lens group.

[0010] According to some embodiments of the present invention, the aspherical lens having negative optical power in the first lens group satisfies the following conditional formula: -3.0≤Fasp / F≤-1, 0.5≤Sasp / F≤1.2, in, Fasp: the focal length of the aspherical lens; Sasp: is the sagittal depth of the concave side of the aspheric lens; F: is the focal length of the wide-angle optical lens for photography.

[0011] According to some embodiments of the present invention, the aspheric curve driving equation of the aspheric lens included in the first lens group is as follows: ,in, R: is the radius of curvature of the aspheric surface; Y: radial coordinate; K: is the cone coefficient of the quadratic surface; Z: is the sagittal height of the surface along the optical axis; AR1: 1st order aspheric coefficient; AR2: 2nd order aspheric coefficient; AR3: 3rd order aspheric coefficient; According to the above rules, ARn: is the nth order aspheric coefficient.

[0012] According to some embodiments of the present invention, the aspheric lens included in the first lens group is a plastic aspheric lens.

[0013] According to some embodiments of the present invention, the second lens group includes only one sixth lens having positive optical power.

[0014] According to some embodiments of the present invention, during the focusing process from infinity to close distance on the object side, the second lens group moves along the optical axis toward the image side.

[0015] According to some embodiments of the present invention, the third lens group includes at least 8 lenses.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 Schematic diagram of the lens arrangement structure of the first wide-angle photography optical lens according to an embodiment of the present invention; Figure 2 for Figure 1 Spherical aberration diagram of the lens; Figure 3 for Figure 1 Astigmatism field curvature diagram of the lens; Figure 4 for Figure 1 Distortion diagram of the lens; Figure 5 Schematic diagram of the lens arrangement structure of a second wide-angle photography optical lens according to an embodiment of the present invention; Figure 6 for Figure 5 Spherical aberration diagram of the lens; Figure 7 for Figure 5 Astigmatism field curvature diagram of the lens; Figure 8 for Figure 5 Distortion diagram of the lens.

[0018] Figure Number: A first lens group 100 , a second lens group 200 , a third lens group 300 , and an aperture stop 400 . DETAILED DESCRIPTION

[0019] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0020] In the description of the present invention, it should be understood that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0022] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0023] In some existing structures of wide-angle optical lenses for photography, the lens group structure used has the problem of a small field of view angle, and the front lens has a large diameter, which makes the product bulky and inconvenient to carry. For example, in the patent document with publication number KR20180119885A, in multiple embodiments disclosed therein, the field of view angle of the lens is small. Since the volume of the lens is limited by the maximum lens size, the front lens in the disclosed embodiments has a large diameter, resulting in a large product volume.

[0024] In another lens group structure, for example, the patent document with publication number CN117706739A, the focusing lens group of the lens contains multiple lenses. For example, it can be seen from the structure of the attached figure that the second lens group used for focusing has four lenses. The focusing lens group with multiple lenses is heavy, which will affect the moving speed of the focusing lens group during focusing, that is, affect the focusing speed, and there may be noise during focusing.

[0025] Reference Figure 1 As shown, a wide-angle optical lens for photography according to an embodiment of the present invention comprises a first lens group 100, a second lens group 200 and a third lens group 300 which are sequentially arranged from the object side to the image side along the optical axis.

[0026] The first lens group 100 has negative power and includes at least one aspherical lens; the second lens group 200 has positive power; the third lens group 300 has positive power; an aperture stop 400 is provided between the second lens group 200 and the third lens group 300; the first lens group 100, the second lens group 200 and the third lens group 300 respectively satisfy the following conditional formulas: -3.0≤F1 / F≤-0.8(1) 2.0≤F2 / F≤4.0(2) 2.5≤F3 / F≤4.0(3) Among them, F1: is the focal length of the first lens group 100; F2: is the focal length of the second lens group 200; F3: is the focal length of the third lens group 300; F: is the focal length of the photographic wide-angle optical lens.

[0027] The photographic wide-angle optical lens satisfying the conditional formula has a relatively short focal length, a small size, and a higher resolution. The first lens group 100 satisfies the conditional formula (1), which can reduce the aperture of the first lens group 100, further miniaturize the size of the first lens group 100, and reduce the burden of spherical aberration correction of the third lens group 300. At the same time, the refractive power of the first lens group 100 is moderate, and the off-axis aberration is easy to balance and correct. The second lens group 200 satisfies the conditional formula (2), and the second lens group 200 has a suitable refractive power and focusing stroke, which reduces the burden of balancing aberrations of the rear group. The third lens group 300 satisfies the conditional formula (3), which can reduce the burden of the aspherical lens in the first lens group 100 on balancing and correcting off-axis aberrations, making the surface shape of the aspherical lens simpler and easier to process, while achieving high resolution.

[0028] More specifically, if the data of the first lens group 100 is less than the lower limit of the conditional expression (1), the aperture of the first lens group 100 will increase, which is not conducive to the miniaturization of the volume of the first lens group 100. The aperture of the first lens group 100 refers to the size of the largest lens in the lens group. At the same time, if the data of the first lens group 100 is less than the lower limit of the conditional expression (1), the spherical aberration correction burden of the third lens group 300 will also increase. If the data of the first lens group 100 is greater than the upper limit of the conditional expression (1), the refractive power of the first lens group 100 will increase, the angle of the exit light of the first lens group 100 will become steeper, and the off-axis aberration will become difficult to balance and correct.

[0029] If the data of the second lens group 200 is less than the lower limit of conditional expression (2), the refractive power of the second lens group 200 will increase, and the focusing stroke of the second lens group 200 will be reduced. However, the spherical aberration of the second lens group 200 will increase, and the burden of balancing aberrations of the rear group will also increase. The rear group refers to the lens group after the second lens group 200 along the optical path. If the data of the second lens group 200 is greater than the upper limit of conditional expression (2), the refractive power of the second lens group 200 will decrease, and the focusing stroke of the second lens group 200 will be increased. However, the refractive power of the rear group will increase, which is not conducive to balancing off-axis aberrations of the rear group, especially astigmatism and coma.

[0030] It should be understood that the third lens group 300 has a plurality of lenses, including lenses with positive refractive power and lenses with negative refractive power.

[0031] If the data of the third lens group 300 is less than the lower limit of the conditional expression (3), the refractive power of the third lens group 300 increases, and the refractive power of the lens with positive focal power included in the third lens group 300 increases, resulting in a steeper angle of the emitted light, thereby increasing the sensitivity of the lens, and at the same time increasing the burden of the aspherical lens in the first lens group 100 on the balance and correction of off-axis aberrations, and the surface shape of the aspherical lens will become more complex and difficult to process. If the data of the third lens group 300 is greater than the upper limit of the conditional expression (3), the refractive power of the third lens group 300 will be weakened. In order to maintain the refractive power of the entire lens, the negative focal power of the first lens group 100 also needs to be weakened, resulting in the incident light being at a higher light height in the first lens group 100, which will increase the aperture of the front lens of the first lens group 100, and at the same time increase the spherical aberration, making it difficult to balance the various aberrations and achieving high-performance resolution.

[0032] The first lens group 100 includes at least one aspherical lens. Preferably, at least one aspherical lens with negative optical power is included in the aspherical lenses included in the first lens group 100.

[0033] It can be understood that the aspherical lens with negative optical power in the first lens group 100 satisfies the following conditional formula: -3.0≤Fasp / F≤-1(4) 0.5≤Sasp / F≤1.2(5) Among them, Fasp is the focal length of the aspherical lens; Sasp is the sagittal depth of the concave side of the aspherical lens; F is the focal length of the photographic wide-angle optical lens.

[0034] If the data of the aspherical lens is lower than the lower limit of conditional expression (4), the refractive power of the aspherical lens will decrease, and the number of lenses of the first lens group 100 needs to be increased to compensate for the lost refractive power, which will also increase the outer diameter of the first lens group 100. If the data of the aspherical lens is greater than the upper limit of conditional expression (4), the refractive power of the aspherical lens will increase, and the angle of the emitted light will also increase, resulting in an increase in the sensitivity of the aspherical lens.

[0035] If the data of the aspherical lens is lower than the lower limit of conditional expression (5), the surface shape of the edge of the aspherical lens will become flat, and the corresponding refractive power will be reduced. It is also necessary to increase the number of lenses in the first lens group 100 to compensate for the lost refractive power, and the outer diameter of the first lens group 100 will also increase. If the data of the aspherical lens is greater than the upper limit of conditional expression (5), the concave side of the aspherical lens will be too deep, or the tangent slope of the lens edge will be too large, resulting in difficulty in processing the aspherical lens.

[0036] It can be understood that the aspheric curve driving equation of the aspheric lens included in the first lens group 100 is as follows: (6), where R is the radius of curvature of the aspheric surface; Y is the radial coordinate; K is the conic coefficient of the quadratic surface; Z is the vector height of the surface along the optical axis; AR1 is the first-order aspheric coefficient; AR2 is the second-order aspheric coefficient; AR3 is the third-order aspheric coefficient; according to the above rule, ARn is the n-order aspheric coefficient.

[0037] It is understandable that the aspheric lens included in the first lens group 100 is a plastic aspheric lens. Of course, the aspheric lens can also be a glass aspheric lens, but compared with a glass aspheric lens, the use of a plastic aspheric lens can reduce costs.

[0038] It is understandable that the first lens group 100 includes 5 lenses. Preferably, from the object side to the image side, the first lens group 100 includes a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, and a fifth lens with negative optical power.

[0039] It can be understood that the second lens group 200 only includes one sixth lens with positive refractive power.

[0040] It can be understood that, in the focusing process from infinity to close distance on the object side, the second lens group 200 moves along the optical axis toward the image side.

[0041] The second lens group 200 is used as a focusing group and is composed of a sixth lens with a positive optical angle. The focusing group has a small number of lenses, a low weight, and a high focusing speed.

[0042] It can be understood that the third lens group 300 includes at least 8 lenses.

[0043] Embodiment 1: The parameters of the wide-angle photography optical lens of this embodiment are as follows: EFL: 10mm; Fno: 2.85; 2ω: 129.9°; Among them, EFL is the effective focal length of the optical lens, Fno is the aperture, and 2ω is the field of view.

[0044] F1 / F=-1.05, which satisfies conditional formula (1); F2 / F=2.70, which satisfies conditional formula (2); F3 / F=2.93, which satisfies conditional formula (3); Fasp / F=-2.41, which satisfies conditional formula (4); Sasp / F=0.99, which satisfies conditional formula (5).

[0045] The parameters of the wide-angle photography optical lens of this embodiment also meet the contents of Table 1, Table 2 and Table 3.

[0046] Table 1 Parameters of the wide-angle photography optical lens of Example 1

[0047] In Table 1, Image is the image side; Radius is the radius of curvature of each surface; Thickness is the distance between each lens and the thickness of the lens; Nd is the refractive index of each glass of d line; Vd is the Abbe number of the glass; ASP indicates that the surface is aspherical.

[0048] Table 2 Focusing interval parameters of the wide-angle photography optical lens of Example 1

[0049] In Table 2, FAR stands for far side, that is, the lens focuses on far view; NEAR stands for near side, that is, the lens focuses on near view.

[0050] Table 3 Aspherical lens parameters of the wide-angle photography optical lens of Example 1

[0051] In Table 3, R is the radius of curvature of the aspheric surface; K is the conic coefficient of the quadratic surface; AR1 is the first-order aspheric coefficient; AR2 is the second-order aspheric coefficient; AR3 is the third-order aspheric coefficient; according to the above rule, ARn is the n-order aspheric coefficient. Among them, 1.246987E-04 refers to 1.246987×10 -4 , and the same applies to the rest.

[0052] The lens arrangement structure of the wide-angle photography optical lens of Example 1 can refer to Figure 1 As shown. And Figure 2 , Figure 3 , Figure 4 The spherical aberration, astigmatism, field curvature, and distortion diagrams of the wide-angle photography optical lens of Example 1 are shown.

[0053] It is important to understand that Figure 1 In the wide-angle photography optical lens, the first lens group 100 is also recorded as G1, the second lens group 200 is also recorded as G2, and the third lens group 300 is also recorded as G3. In the entire wide-angle photography optical lens, the order of lens arrangement from the object side to the image side is L1 for the first lens, L2 for the second lens, and Ln for the nth lens in this order. For example, lens G3L10 refers to the 10th lens, and the lens belongs to the third lens group 300. Among them, the aperture stop 400 is recorded as ST0, and the image plane is recorded as IMA.

[0054] Embodiment 2: The parameters of the wide-angle photography optical lens of this embodiment are as follows: EFL: 10mm; Fno: 2.85; 2ω: 130.1°; Among them, EFL is the effective focal length of the optical lens, Fno is the aperture, and 2ω is the field of view.

[0055] F1 / F=-1.00, which satisfies conditional formula (1); F2 / F=3.19, which satisfies conditional formula (2); F3 / F=2.99, which satisfies conditional formula (3); Fasp / F=-1.98, which satisfies conditional formula (4); Sasp / F=0.71, which satisfies conditional formula (5).

[0056] The parameters of the wide-angle photography optical lens of this embodiment also meet the contents of Table 4, Table 5 and Table 6.

[0057] Table 4 Parameters of the wide-angle photography optical lens of Example 2

[0058] In Table 4, Image is the image side; Radius is the curvature radius of each surface; Thickness is the distance between each lens and the thickness of the lens; Nd is the refractive index of each glass of d line; Vd is the Abbe number of the glass; ASP indicates that the surface is aspherical.

[0059] Table 5 Focus interval parameters of the wide-angle photography optical lens of Example 2

[0060] In Table 5, FAR stands for far side, that is, the lens focuses on far view; NEAR stands for near side, that is, the lens focuses on near view.

[0061] Table 6 Aspherical lens parameters of the wide-angle photography optical lens of Example 2

[0062] In Table 6, R is the radius of curvature of the aspheric surface; K is the conic coefficient of the quadratic surface; AR1 is the first-order aspheric coefficient; AR2 is the second-order aspheric coefficient; AR3 is the third-order aspheric coefficient; according to the above rule, ARn is the n-order aspheric coefficient. Among them, 2.142710E-04 refers to 2.142710×10 -4 , and the same applies to the rest.

[0063] The lens arrangement structure of the wide-angle photography optical lens of Example 2 can refer to Figure 5 As shown. And Figure 6 , Figure 7 , Figure 8 The spherical aberration, astigmatism, field curvature, and distortion diagrams of the wide-angle photography optical lens of Example 1 are shown.

[0064] It is important to understand that Figure 5 In the wide-angle photography optical lens, the first lens group 100 is also recorded as G1, the second lens group 200 is also recorded as G2, and the third lens group 300 is also recorded as G3. In the entire wide-angle photography optical lens, the order of lens arrangement from the object side to the image side is L1 for the first lens, L2 for the second lens, and Ln for the nth lens in this order. For example, lens G3L10 refers to the 10th lens, and the lens belongs to the third lens group 300. Among them, the aperture stop 400 is recorded as ST0, and the image plane is recorded as IMA.

[0065] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A wide-angle optical lens for photography, characterized in that: include: A first lens group (100), a second lens group (200) and a third lens group (300) are arranged in sequence from the object side to the image side along the optical axis; The first lens group (100) has negative optical power, and the first lens group (100) comprises at least one aspherical lens; The second lens group (200) has positive optical power; The third lens group (300) has positive optical power; An aperture stop (400) is provided between the second lens group (200) and the third lens group (300); The first lens group (100), the second lens group (200) and the third lens group (300) respectively satisfy the following conditional expressions: -3.0≤F1 / F≤-0.8(1) 2.0≤F2 / F≤4.0(2) 2.5≤F3 / F≤4.0(3) in, F1: is the focal length of the first lens group (100); F2: is the focal length of the second lens group (200); F3: is the focal length of the third lens group (300); F: is the focal length of the wide-angle optical lens for photography.

2. The wide-angle optical lens for photography according to claim 1, characterized in that: The first lens group (100) comprises five lenses.

3. The wide-angle optical lens for photography according to claim 2, characterized in that: From the object side to the image side, the first lens group (100) comprises, in sequence, a first lens with negative optical power, a second lens with negative optical power, a third lens with negative optical power, a fourth lens with positive optical power, and a fifth lens with negative optical power.

4. The wide-angle optical lens for photography according to claim 1, characterized in that: Among the aspheric lenses included in the first lens group (100), there is at least one aspheric lens with negative optical power.

5. The wide-angle optical lens for photography according to claim 4, characterized in that: The aspherical lens with negative optical power in the first lens group (100) satisfies the following conditional formula: -3.0≤Fasp / F≤-1(4) 0.5≤Sasp / F≤1.2(5) in, Fasp: the focal length of the aspherical lens; Sasp: is the sagittal depth of the concave side of the aspheric lens; F: is the focal length of the wide-angle optical lens for photography.

6. The wide-angle optical lens for photography according to claim 4, characterized in that: The aspheric curve driving equation of the aspheric lens included in the first lens group (100) is as follows: (6), where R: is the radius of curvature of the aspheric surface; Y: radial coordinate; K: is the cone coefficient of the quadratic surface; Z: is the sagittal height of the surface along the optical axis; AR1: 1st order aspheric coefficient; AR2: 2nd order aspheric coefficient; AR3: 3rd order aspheric coefficient; According to the above rules, ARn: is the nth order aspheric coefficient.

7. The wide-angle optical lens for photography according to claim 1, characterized in that: The aspheric lens included in the first lens group (100) is a plastic aspheric lens.

8. The wide-angle optical lens for photography according to claim 1, characterized in that: The second lens group (200) comprises only one sixth lens having positive optical power.

9. The wide-angle optical lens for photography according to claim 1, characterized in that: During the focusing process from infinity to a close distance on the object side, the second lens group (200) moves along the optical axis toward the image side.

10. The wide-angle optical lens for photography according to claim 1, characterized in that: The third lens group (300) includes at least 8 lenses.

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