Portrait lens

Abstract

The utility model discloses a portrait lens which is sequentially provided with a first lens group with positive focal power, an aperture diaphragm, a second positive lens group with positive focal power and a third negative lens group with negative focal power from an object side. The first lens group sequentially comprises a first lens, a second positive lens, a third negative lens with negative focal power, a fourth lens, a fifth positive lens and a sixth negative lens from object measurement to image measurement; in the focusing process from infinity to the nearest end object distance, the second positive lens group moves towards the object end along with the optical axis, and the first lens group and the third negative lens group are fixed relative to the image plane. The standard portrait lens adopted by the device successfully achieves the goals of large aperture, high imaging quality, light weight and effective respiratory effect inhibition through accurate lens group design and reasonable focal power distribution, meets the requirements of a larger part of consumers, provides a better imaging solution for photography and movie and television industries, and has a wide application prospect. And the user experience is greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of lens, specifically relates to a portrait lens. BACKGROUND

[0002] In modern photography and video production, the design and performance of the lens directly affect the imaging quality and user experience. With the continuous progress of technology, consumers' requirements for the lens are also increasing, especially in terms of portability, imaging quality and cost control. Traditional lens design often faces problems such as large size, high cost and poor imaging effect, therefore, it is particularly important to develop a new standard portrait lens.

[0003] In recent years, digital still cameras, digital reflex cameras and other devices using solid-state imaging devices such as CCD (Charge-Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) have rapidly spread. The spread of such digital cameras and other devices has led to an increasing demand for high-performance imaging lenses corresponding to a high number of pixels. In addition, recently, such demand has been growing not only for zoom lenses but also for single-focus lenses with a fixed focal length. SUMMARY

[0004] In view of the deficiencies of the prior art, the utility model aims to provide a portrait lens, which solves the above technical problems existing in the prior art.

[0005] The utility model can achieve the purpose by the following technical scheme:

[0006] A portrait lens, sequentially arranged from the object side: a first lens group with positive refractive power, an aperture stop, a second positive lens group with positive refractive power, a third negative lens group with negative refractive power;

[0007] The first lens group sequentially includes a first lens with negative refractive power, a second positive lens with positive refractive power, a third negative lens with negative refractive power, a fourth lens with positive refractive power, a fifth positive lens with positive refractive power, and a sixth negative lens with negative refractive power;

[0008] The second positive lens group includes a seventh negative lens with negative refractive power and an eighth positive lens with positive refractive power;

[0009] The third negative lens group sequentially includes a ninth negative lens with negative refractive power and a tenth positive lens with positive refractive power;

[0010] During the focusing process from infinity to the nearest object distance, the second positive lens group moves towards the object end along the optical axis, and the first lens group and the third negative lens group are fixed relative to the image plane;

[0011] Further, the second positive lens and the third negative lens form a cemented lens group.

[0012] Further, the fifth positive lens and the sixth negative lens form a cemented lens group.

[0013] Further, the first lens group satisfies the following conditional expression:

[0014] 0.8 < F1 / F < 2;

[0015] Wherein, F is the total focal length of the lens, and F1 represents the combined focal length of the first lens group.

[0016] Further, the second positive lens group satisfies the following conditional expression:

[0017] -4 < F2a / F2 < 0;

[0018] And 0 < F2b / F2 < 1;

[0019] Wherein: F2a is the focal length of the negative lens, F2b is the focal length of the positive lens, and F2 is the total focal length of the second positive lens group.

[0020] Further, the third negative lens group satisfies the following conditional expression:

[0021] -2 < F3b / F3a < 0;

[0022] Wherein: F3a is the ninth negative lens focal length, and F3b is the tenth positive lens focal length.

[0023] The beneficial effects of the present application are:

[0024] 1. The device adopts an innovative lens group configuration, aiming to solve the shortcomings of traditional lenses in the focal length adjustment process. The lens is sequentially configured from the object side with a first lens group with positive refractive power, an aperture stop, a second positive lens group with positive refractive power, and a third negative lens group with negative refractive power. Through this design, the second positive lens group can move along the optical axis to the object end during focusing, while the first lens group and the third negative lens group are relatively fixed on the image plane. This structure not only improves the compactness of the lens, but also effectively reduces the production cost, while ensuring high-quality imaging effect.

[0025] 2. Although the device is a large aperture, it can fully reduce aberrations, so that the full field of view can obtain excellent imaging, the focusing lens is lightweight, and the breathing effect is effectively inhibited, and the user experience is greatly improved.

[0026] 3. The imaging lens provided by the device is more miniaturized, low-cost, high-image quality, and fully suppresses the breathing effect, which can meet the needs of a larger part of consumers. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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 use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 is a schematic diagram illustrating the lens structure of an imaging lens according to an embodiment.

[0029] Figure 2 is a diagram illustrating spherical aberration of the imaging lens according to the embodiment at infinite focus (INF).

[0030] Figure 3 is a diagram illustrating astigmatic distortion of the imaging lens according to the embodiment at infinite focus (INF). DETAILED DESCRIPTION

[0031] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] like Figure 1 、 Figure 2 、 Figure 3 As shown, an embodiment of the present invention provides a standard portrait lens, which is configured in sequence from the object side: a first lens group GR1 with positive optical power, an aperture stop STP, a second positive lens group GR2 with positive optical power, and a third negative lens group GR3 with negative optical power.

[0033] During focusing from infinity to the closest object distance, the second positive lens group GR2 moves along the optical axis toward the object, while the first lens group GR1 and the third negative lens group GR3 remain fixed relative to the image plane. This imaging lens is more compact than conventional lenses of the same focal length, offering lower cost, higher image quality, and significantly reduced breathing, meeting the needs of a wider range of consumers.

[0034] The first lens group GR1 comprises, in order from the object to the image, a first lens G1 having negative refractive power, a second positive lens G2 having positive refractive power, a third negative lens G3 having negative refractive power, a fourth lens G4 having positive refractive power, a fifth positive lens G5 having positive refractive power, and a sixth negative lens G6 having negative refractive power, wherein the second positive lens G2 and the third negative lens G3 form a cemented lens group, and the fifth positive lens G5 and the sixth negative lens G6 form a cemented lens group.

[0035] With reference to the relevant parameters listed in Table 3 and Table 4, the first lens group GR1 satisfies the following conditional expression (1):

[0036] 0.8 < F1 / F < 2 (1),

[0037] wherein F is the total focal length of the lens, and F1 represents the combined focal length of the first lens group GR1.

[0038] The above conditional expression (1) limits the focal length range of the first lens group GR1 of the lens. If greater than the upper limit of the conditional expression, the overall length of the lens will be too long, which is not conducive to the requirement of portability. If less than the lower limit of the conditional expression, the focal length F1 will be too large, which will make it difficult to balance and correct the aberrations of the entire system.

[0039] The second positive lens group GR2 comprises a seventh negative lens G7 having negative refractive power and an eighth positive lens G8 having positive refractive power.

[0040] The following conditional expressions (2) and (3) are satisfied:

[0041] -4 < F2a / F2 < 0 (2);

[0042] and 0 < F2b / F2 < 1 (3);

[0043] wherein F2a is the focal length of the negative lens G7, F2b is the focal length of the positive lens G8, and F2 is the total focal length of the second positive lens group GR2.

[0044] The conditional expressions (2) and (3) determine the refractive power distribution of different lenses in the second positive lens group GR2. This distribution can adjust the total focal length of the second positive lens group GR2, suppress the breathing effect of the system, and satisfy the conditional expressions (2) and (3). The negative refractive power lens G7 and the positive refractive power lens G8 included in the second positive lens group GR2 balance the aberrations with each other, reduce the incident angle of the second positive lens group, suppress the breathing effect, and achieve the balance of the aberrations of the overall system.

[0045] The third negative lens group GR3 comprises, in order, a ninth negative lens G9 having negative refractive power and a tenth positive lens G10 having positive refractive power.

[0046] The following conditional expression (4) is satisfied:

[0047] -2 < F3b / F3a < 0 (4),

[0048] where F3a is the focal length of the ninth lens G9 and F3b is the focal length of the tenth lens G10.

[0049] The conditional expression (4) determines the internal power distribution of the third negative lens group GR3 to achieve the complementation of the aberration of the first lens group, and only two pieces of lenses are needed to achieve the purpose of excellent light weight aberration.

[0050] The above design of the focal length of each lens of the lens realizes a large aperture, but can sufficiently reduce various aberrations, so that excellent imaging can be obtained in the full field of view, the focusing lens is light in weight, and the breathing effect is effectively inhibited.

[0051] In order to more clearly understand the present application, the following is the specific data and aberration of the embodiment.

[0052] Hereinafter, the imaging lens of the present application will be described in detail based on the drawings. In the lens data, the refractive index and the Abbe number are the values of the d line. Among them, in the optical lens related data, the unit of length is mm, and the unit will be omitted.

[0053] It should be noted that the symbols used in the table and the following description are as follows:

[0054] 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 surface and the i+1-th surface; "n d " is the refractive index; "vd" is the Abbe number; "Fno." is the F number; "ω" is the half field angle. As for the surface number, "ASP" means that the surface is an aspherical surface, and as for the radius of curvature, "Infinity" and "∞" mean that the surface is a plane. "IMG" means an imaging surface. In addition, in Table 2, due to the focusing type of the lens, the position of the second positive lens group moves forward and backward at different object distances, INF is the infinite object distance, X20 is the object distance 980.71mm, MOD is the closest focusing object distance 300mm. D1 and D2 are the intervals of the focusing lens group and the front and rear lenses respectively. The two intervals change at different object distances to achieve the effect of clear focusing.

[0055] In addition, the refractive index and the Abbe number are the refractive index and the Abbe number about the d line (wavelength 587.6nm).

[0056] Various numerical data of the optical system of the embodiment:

[0057] f = 50.23mm, Fno = 1.8, 2w = 45.4°

[0058] Table 1

[0059]

[0060]

[0061] Table 2

[0062]

[0063] Table 3

[0064]

[0065]

[0066] Table 4

[0067] Conditional Examples 1 0.8 < F1 / F < 2 1.680 2 -4 < F2a / F2 < 0 -0.957 3 0 < F2b / F2 < 1 0.538 4 -2 < F3b / F3a < 0 -1.222

[0068] Meanwhile, Figure 2 is a graph illustrating the chromatic aberration of the imaging lens according to the embodiment at infinite focus (INF); wherein F, d, C respectively represent the chromatic aberration of visible light wavelengths of 486nm, 587.6nm, 656nm.

[0069] Figure 3 is a graph illustrating the astigmatism distortion of the imaging lens according to the embodiment at infinite focus (INF); wherein T, S respectively represent the meridional field curvature and sagittal field curvature at visible light 587.6nm.

[0070] The basic principle, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principle of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application.

Claims

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

2. The portrait lens according to claim 1, characterized in that: The second positive lens (G2) and the third negative lens (G3) form a cemented lens group.

3. The portrait lens according to claim 1, wherein: The fifth positive lens (G5) and the sixth negative lens (G6) form a cemented lens group.

4. The portrait lens according to claim 1, wherein: The first lens group (GR1) satisfies the following conditional formula: 0.8 <F1 / F<2; Wherein, F is the total focal length of the lens, and F1 represents the composite focal length of the first lens group (GR1).

5. The portrait lens according to claim 1, wherein: The second positive lens group (GR2) satisfies the following conditional formula: -4 <F2a / F2<0; and 0 <F2b / F2<1; Wherein: F2a is the focal length of the negative lens (G7), F2b is the focal length of the positive lens (G8), and F2 is the total focal length of the second positive lens group (GR2).

6. The portrait lens according to claim 1, wherein: The third negative lens group (GR3) satisfies the following conditional formula: -2 <F3b / F3a<0; Where: F3a is the focal length of the ninth negative lens (G9), and F3b is the focal length of the tenth positive lens (G10).

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