Large-aperture internal focusing imaging lens

Abstract

The utility model discloses a large-aperture internal focusing imaging lens, which sequentially comprises a first lens group, a second lens group and a third lens group from an object side to an image side, the first lens group sequentially comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with positive focal power, a fourth lens with positive focal power and a fifth lens with negative focal power from the object side to the image side; the second lens group comprises a sixth lens with negative focal power; and the third lens group sequentially comprises a seventh lens with positive focal power, an eighth lens with negative focal power, a ninth lens with positive focal power and a tenth lens with negative focal power. The imaging lens provided by the utility model is a portrait large-aperture standard lens which is smaller in size, low in cost and high in image quality compared with a common lens in a same focal length, and can meet the requirements of a larger part of consumers.

Description

Technical Field

[0001] The utility model belongs to the technical field of aperture lenses, and in particular relates to a large aperture inner-focus imaging lens. Background Art

[0002] In recent years, digital still cameras and digital mirrorless cameras utilizing solid-state imaging devices (such as CCDs (charge-coupled devices) and CMOSs ​​(complementary metal oxide semiconductors)) have rapidly gained popularity. The proliferation of these digital cameras and other devices has led to a growing demand for high-performance imaging lenses that can handle high pixel counts. Furthermore, this demand is growing not only for zoom lenses but also for single-focus lenses with fixed focal lengths.

[0003] Existing imaging lenses often achieve high imaging quality by using expensive materials and complex lens stacks, which increases costs and wastes materials. Furthermore, existing lens designs are often overly complex, increasing both manufacturing difficulty and maintenance costs.

[0004] Due to the large number of lenses and heavy materials, existing large-aperture lenses are often heavy, making them difficult to carry and use, especially in situations where lightweight equipment is required. Furthermore, existing lenses have shortcomings in correcting chromatic aberrations and aberrations, making it difficult to achieve excellent imaging quality, especially at large apertures and long focal lengths. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a large aperture inner focus imaging lens to solve the above-mentioned technical problems existing in the existing technology.

[0006] The purpose of the utility model can be achieved through the following technical solutions:

[0007] A large aperture inner focus imaging lens, which includes a first lens group, a second lens group, and a third lens group in sequence from the object side to the image side.

[0008] The first lens group includes, from the object side to the image side, a first lens with negative refractive power, a second lens with positive refractive power, a third lens with positive refractive power, a fourth lens with positive refractive power, and a fifth lens with negative refractive power;

[0009] The second lens group includes a sixth lens having negative optical power;

[0010] The third lens group includes, in sequence, a seventh lens having positive focal power, an eighth lens having negative focal power, a ninth lens having positive focal power, and a tenth lens having negative focal power;

[0011] Wherein: during the focusing process from infinity to the closest object distance, the second lens group moves along with the optical axis toward the image end, and the first lens group and the third lens group are fixed relative to the image plane.

[0012] Furthermore, the first lens group satisfies the following conditional formula:

[0013] 0.7 <F1 / F<3;

[0014] Wherein, F is the total focal length of the imaging lens, and F1 is the focal length of the first lens combination.

[0015] Furthermore, the first lens and the second lens group form a cemented lens group.

[0016] Furthermore, the fourth lens and the fifth lens form a cemented lens group and satisfy the following conditional formula:

[0017] 1.45 <Nd4<1.6,95> Vd4>75;

[0018] Wherein: Nd4 and Vd4 are the refractive index and Abbe number of the material of the fourth lens group respectively.

[0019] Furthermore, the seventh lens, the eighth lens and the ninth lens form a triplet lens group; they are arranged according to positive and negative positive power and satisfy the following conditional formula:

[0020] 1.5 <Nd7<Nd8<Nd9<1.85;

[0021] Among them, Nd7, Nd8, and Nd9 are the refractive indices of the materials of the seventh lens, the eighth lens, and the ninth lens respectively.

[0022] Furthermore, the large aperture inner focus imaging lens satisfies the following conditional formula:

[0023] 15 <BF<21;

[0024] Wherein, BF is the distance between the lens surface closest to the image side and the image plane in the imaging lens.

[0025] Beneficial effects of the utility model:

[0026] 1. The device adopts a large aperture internal focus imaging lens. The internal focusing component of the lens is realized by a single lens in the second lens group. The focusing lens is very light, which can greatly reduce the load of the driving motor, and can achieve fast focusing of the lens, as well as the small and portable size of the lens.

[0027] 2. The imaging lens designed for this device uses a small number of lenses and ordinary materials, but achieves a large aperture, low cost, and excellent imaging portable lens to meet the needs of most consumers. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0029] Figure 1 1 is a schematic diagram of the lens structure of an imaging lens according to an embodiment of the present utility model;

[0030] Figure 2 is a spherical aberration diagram of the imaging lens according to the embodiment of the present invention at infinity focus (INF);

[0031] Figure 3 FIG. 4 is an astigmatism distortion diagram of the imaging lens according to the embodiment of the present invention at infinity focus (INF). DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] like Figure 1 As shown, the present invention adopts a large aperture internal focus imaging lens, which includes, from the object side to the image side, a first lens group GR1 with positive focal power, an aperture STP, a second lens group GR2 with negative focal power, and a third lens group GR3 with positive focal power.

[0034] The first lens group GR1 includes, from the object side to the image side, a first lens G1 with negative optical power, a second lens G2 with positive optical power, a third lens G3 with positive optical power, a fourth lens G4 with positive optical power, and a fifth lens G5 with negative optical power; in this case, the first lens G1 and the second lens G2 are a cemented lens group, and the fourth lens G4 and the fifth lens G5 are a cemented lens group.

[0035] The second lens group GR2 includes a sixth lens G6 having negative refractive power;

[0036] The third lens group GR3 includes, in order, a seventh lens G7 with positive refractive power, an eighth lens G8 with negative refractive power, a ninth lens G9 with positive refractive power, and a tenth lens G10 with negative refractive power; the seventh lens G7, the eighth lens G8, and the ninth lens G9 form a cemented triplet lens group.

[0037] In the process of focusing from infinity to the closest object distance, the second lens group GR2 moves along the optical axis toward the image end, and the first lens group GR1 and the third lens group GR3 are fixed relative to the image plane.

[0038] The first lens group GR1 satisfies the following conditional formula:

[0039] 0.7 <F1 / F<3; (1)

[0040] Wherein, F is the total focal length of the imaging lens, and F1 is the composite focal length of the first lens group GR1.

[0041] Furthermore, the fourth lens G4 and the fifth lens G5 form a cemented lens group and satisfy the following conditional formula:

[0042] 1.45 <Nd4<1.6; (2)

[0043] 95> Vd4>75; (3)

[0044] Wherein: Nd4 and Vd4 are the refractive index and Abbe number of the material of the fourth lens group G4 respectively.

[0045] Furthermore, the seventh lens G7, the eighth lens G8 and the ninth lens G9 form a triplet lens group; they are arranged according to positive and negative positive focal powers and satisfy the following conditional formula:

[0046] 1.5 <Nd7<Nd8<Nd9<1.85; (4)

[0047] Wherein, Nd7, Nd8, and Nd9 are the refractive indices of the materials of the seventh lens G7, the eighth lens G8, and the ninth lens G9, respectively.

[0048] The large aperture internal focus imaging lens meets the following conditions:

[0049] 15 <BF<21; (5)

[0050] Wherein, BF is the distance between the lens surface closest to the image side and the image plane in the imaging lens.

[0051] As can be seen from the above, conditional equations (1) and (5) ensure the overall length of the lens, making the entire lens lighter and smaller in size, making it easier to carry.

[0052] At the same time, the double-cemented lens group of conditions (2) and (3) optimizes the chromatic aberration of the system.

[0053] The triplet lens group of conditional formula (4) further optimizes system chromatic aberration and other aberrations by arranging materials with low refractive index, medium refractive index and high refractive index, and reduces the number of lenses and the total length of the third lens group.

[0054] The internal focusing component of the telephoto and large aperture lens involved in this device is realized by a single lens group. The focusing lens is very light, which can greatly reduce the load of the driving motor, realize the rapid focusing of the lens, and realize the miniaturization of the lens;

[0055] Conditions (1) and (2) can ensure the telephoto characteristics of the lens and make the system have a smaller depth of field. At the same time, it is beneficial to shorten the overall length of the system and reduce the tolerance sensitivity of the entire system, making it easier to compose during the shooting process. At the same time, the large aperture can meet the needs of shooting in dim indoors and night scenes, which can meet the needs of a larger number of consumers.

[0056] The imaging lens of the present invention is described in detail below based on the accompanying drawings. In the lens data, the refractive index and Abbe number are for the d-line. In the optical lens data, the length unit is mm, and the unit is omitted.

[0057] In this embodiment, various numerical data of the optical system are shown in Table 1 below:

[0058] f=51.46mm, Fno=1.8, 2w=47.3°

[0059] Table 1

[0060] Face shape radius thickness Refractive index Abbe number si ri di nd vd 0 STANDARD Infinity Infinity 1 spherical surface -40.292 5.6 1.67 33.1 2 spherical surface 40.292 6.75 1.88 39.2 3 spherical surface -55.284 0.2 4 spherical surface 44.85 2.65 1.82 46.5 5 spherical surface 69.179 0.2 6 spherical surface 34.913 6.8 1.5 81.6 7 spherical surface -42.07 1 1.83 42.7 8 spherical surface Infinity 2 9 Aperture STO Infinity D1 10 spherical surface -329.712 0.8 1.49 70.4 12 spherical surface 24.178 D2 13 spherical surface 46.015 7.55 1.55 45.8 14 spherical surface -17.09 1.2 1.65 39.7 15 spherical surface 26.86 9 1.8 46.6 16 spherical surface -34.06 10 17 spherical surface -23.53 1.5 1.7 30.1 18 spherical surface -108.214 15.32 19 spherical surface Infinity 2 1.52 64.2 20 spherical surface Infinity 1 21 Image plane (IMG)

[0061] In Table 1, "si" represents the surface number; "Ri" is the radius of curvature; "di" is the on-axis surface distance between the i-th and (i+1)-th surfaces; "nd" is the refractive index; "vd" is the Abbe number; "Fno." is the F-number; and "ω" is the half-field angle. Regarding the radius of curvature, "Infinity" and "∞" indicate that the surface is flat. "IMG" represents the imaging surface.

[0062] Table 2 shows the focusing data.

[0063] Table 2

[0064]

[0065] In Table 2, due to the lens's focus mechanism, the second lens group moves forward and backward at different object distances. INF represents the object distance at infinity, X20 represents the object distance of 1059mm, and MOD represents the minimum focus distance of 365mm. D1 and D2 represent the distances between the focusing lens group and the front and rear lens elements, respectively. These two distances vary with object distance to achieve a clear focus.

[0066] Note that the refractive index and Abbe number are those with respect to the d-line (wavelength: 587.6 nm).

[0067] like Figure 2In the figure, F, d, and C represent the spherical aberration of visible light wavelengths of 486 nm, 587.6 nm, and 656 nm, respectively.

[0068] Figure 3 In the figure, T and S represent the meridional field curvature and sagittal field curvature at 587.6 nm of visible light, respectively.

[0069] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and improvements fall within the scope of the present invention as claimed.

Claims

1. A large aperture internal focus imaging lens, comprising, in order from the object side to the image side, a first lens group (GR1), a second lens group (GR2), and a third lens group (GR3), characterized in that: The first lens group (GR1) includes, from the object side to the image side, a first lens (G1) with negative refractive power, a second lens (G2) with positive refractive power, a third lens (G3) with positive refractive power, a fourth lens (G4) with positive refractive power, and a fifth lens (G5) with negative refractive power; The second lens group (GR2) includes a sixth lens (G6) having negative optical power; The third lens group (GR3) includes, in order, a seventh lens (G7) with positive focal power, an eighth lens (G8) with negative focal power, a ninth lens (G9) with positive focal power, and a tenth lens (G10) with negative focal power; In the focusing process from infinity to the closest object distance, the second lens group (GR2) moves along the optical axis toward the image end, and the first lens group (GR1) and the third lens group (GR3) are fixed relative to the image plane.

2. The large aperture inner focus imaging lens according to claim 1, characterized in that: The first lens group (GR1) satisfies the following conditional formula: 0.7 <F1 / F<3; Wherein, F is the total focal length of the imaging lens, and F1 is the composite focal length of the first lens group (GR1).

3. The large aperture inner focus imaging lens according to claim 1, wherein: The first lens (G1) and the second lens (G2) form a cemented lens group.

4. The large aperture inner focus imaging lens according to claim 1, wherein: The fourth lens (G4) and the fifth lens (G5) form a cemented lens group and satisfy the following conditional formula: 1.45 <Nd4<1.6,95> Vd4>75; Wherein: Nd4 and Vd4 are the refractive index and Abbe number of the material of the fourth lens (G4), respectively.

5. The large aperture inner focus imaging lens according to claim 1, wherein: The seventh lens (G7), the eighth lens (G8) and the ninth lens (G9) form a triplet lens group; they are arranged according to positive and negative positive focal powers and satisfy the following conditional formula: 1.5 <Nd7<Nd8<Nd9<1.85; Wherein, Nd7, Nd8, and Nd9 are the refractive indices of the materials of the seventh lens (G7), the eighth lens (G8), and the ninth lens (G9), respectively.

6. The large aperture inner focus imaging lens according to claim 1, wherein: The large aperture inner focus imaging lens satisfies the following conditional formula: 15 <BF<21; Wherein, BF is the distance between the lens surface closest to the image side and the image plane in the imaging lens.

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