Large aperture full-frame photographic lens and photographic device

Abstract

The present application discloses a large aperture full-frame photographic lens and a photographic device. The large aperture full-frame photographic lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, an aperture stop, a third lens group with positive focal power, and a fourth lens group with negative focal power; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, and the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; the second lens group and the third lens group satisfy the following conditional formula: ‑3.6≤F2 / F3≤‑0.6, (1); wherein F2 represents the synthetic focal length of the second lens group, and F3 represents the synthetic focal length of the third lens group. The technical solution of the present application can realize the miniaturization design of the lens while maintaining the high imaging quality of the lens.

Description

Technical Field

[0001] The present application relates to the field of camera technology, and in particular to a large aperture full-frame camera lens and a camera device. Background Art

[0002] In the field of high-end photography, large-aperture full-frame photography lenses are highly favored because they can provide excellent background blur effects and sufficient light intake.

[0003] However, in the prior art, in order to maintain high image quality, complex optical designs and more lens groups are often required, which directly leads to an increase in the size of the lens. The large size not only increases the difficulty of carrying, but also limits the photographer's flexibility in shooting in different scenes.

[0004] Therefore, it is necessary to improve the existing large aperture full-frame photographic lenses. Summary of the invention

[0005] The present application provides a large aperture full-frame photographic lens and a photographic device, aiming to solve the problem of large lens size in existing lenses in order to maintain high imaging quality.

[0006] To achieve the above-mentioned purpose, the present application proposes a large aperture full-frame photography lens. The large aperture full-frame photography lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, an aperture stop, a third lens group with positive focal power, and a fourth lens group with negative focal power; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the first lens group and the fourth lens group remain unchanged relative to the image plane;

[0007] The second lens group and the third lens group satisfy the following conditional formula:

[0008] -3.6≤F2 / F3≤-0.6, (1);

[0009] Wherein, F2 represents the composite focal length of the second lens group, and F3 represents the composite focal length of the third lens group.

[0010] In some embodiments, the shape factor of the lenses with positive optical power in the first lens group |Skp|≤0.5, and the shape factor of the lenses with negative optical power in the first lens group |Skm|≤0.5.

[0011] In some embodiments, the first lens group includes, from the object side to the image side, a first lens having negative optical power, a second lens having positive optical power, a third lens having negative optical power, and a fourth lens having positive optical power;

[0012] Wherein, the second lens and the third lens are combined into a first cemented lens.

[0013] In some embodiments, the Abbe number of the lens with positive optical power in the second lens group satisfies the range: 16≤Vd≤21.

[0014] In some embodiments, the second lens group includes, from the object side to the image side, a fifth lens having positive power and a sixth lens having negative power;

[0015] Wherein, the fifth lens and the sixth lens are combined into a second cemented lens.

[0016] In some embodiments, the Abbe number of the lens with negative optical power in the third lens group satisfies the range: 16≤Vd≤21.

[0017] In some embodiments, the third lens group includes, from the object side to the image side, a seventh lens having negative power, an eighth lens having positive power, and a ninth lens having positive power;

[0018] Wherein, the seventh lens and the eighth lens are combined into a third cemented lens.

[0019] In some embodiments, an average refractive index of lenses in the fourth lens group satisfies the range: 1.8≤Nd≤1.95.

[0020] In some embodiments, the fourth lens group includes, from the object side to the image side, a tenth lens having positive power, an eleventh lens having negative power, a twelfth lens having positive power, a thirteenth lens having negative power, and a fourteenth lens having negative power;

[0021] The tenth lens and the eleventh lens are combined into a fourth cemented lens, and the twelfth lens and the thirteenth lens are combined into a fifth cemented lens.

[0022] In some embodiments, the large aperture full-frame photography lens further satisfies the conditional formula:

[0023] 0.3≤BFL / EFL≤1, (2);

[0024] Among them, BFL is the equivalent air distance from the image side of the last lens in the lens system to the image plane, and EFL is the focal length of the optical system in the infinite focus state.

[0025] The present application also provides a photographic device, which includes an image sensor and the large aperture full-frame photographic lens as described above, wherein the image sensor and the large aperture full-frame photographic lens are detachably connected.

[0026] The technical solution of the present application proposes a large aperture full-frame photographic lens and a photographic device. The large aperture full-frame photographic lens includes, from the object side to the image side, a first lens group with positive focal power, a second lens group with negative focal power, an aperture stop, a third lens group with positive focal power, and a fourth lens group with negative focal power; during the focusing process, the second lens group moves along the optical axis from the object side to the image side, and the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; the second lens group and the third lens group satisfy the following conditional formula: -3.6≤F2 / F3≤-0.6, (1); wherein F2 represents the composite focal length of the second lens group, and F3 represents the composite focal length of the third lens group. The technical solution of the present application forms a large aperture full-frame photographic lens through a reasonable lens group configuration combination, and further provides a focal length ratio relationship between the second lens group and the third lens group. Under this design, it helps to reduce the movement of the second lens group and the third lens group during focusing, thereby facilitating the miniaturization of the lens and maintaining high imaging quality of the lens under this design. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0028] Figure 1 A schematic diagram showing the structure of a large aperture full-frame photographic lens of the present application;

[0029] Figure 2 A schematic diagram showing axial chromatic aberration of the large aperture full-frame photography lens of the present application when focusing at infinity;

[0030] Figure 3 A schematic diagram showing the field curvature and distortion of the large aperture full-frame photography lens of the present application when focusing at infinity;

[0031] Figure 4 A schematic diagram showing axial chromatic aberration of the large aperture full-frame photography lens of the present application at the minimum focusing distance;

[0032] Figure 5 A schematic diagram showing the field curvature and distortion of the large aperture full-frame photography lens of the present application at the minimum focusing distance. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] See also Figure 1 As shown, the present application proposes a large aperture full-frame photography lens, which includes, from the object side to the image side, a first lens group G1 with positive focal power, a second lens group G2 with negative focal power, an aperture stop STP, a third lens group G3 with positive focal power, and a fourth lens group G4 with negative focal power; in the focusing process, the second lens group G2 moves along the optical axis from the object side to the image side, the third lens group G3 moves along the optical axis from the image side to the object side, and the first lens group G1 and the fourth lens group G4 remain unchanged relative to the image plane;

[0035] The second lens group G2 and the third lens group G3 satisfy the following conditional formula:

[0036] -3.6≤F2 / F3≤-0.6, (1);

[0037] Wherein, F2 represents the composite focal length of the second lens group G2, and F3 represents the composite focal length of the third lens group G3.

[0038] In the technical solution of the present application, the first lens group G1, the second lens group G2, the aperture stop STP, the third lens group G3 and the fourth lens group G4 arranged in sequence from the object side to the image side work together to achieve excellent optical performance. Among them, the lens groups with positive and negative optical powers alternately arranged can correct optical problems such as aberrations and distortions, thereby improving the imaging quality.

[0039] In the process of focusing, the second lens group G2 moves along the optical axis from the object side to the image side, while the third lens group G3 moves in the opposite direction. This can significantly reduce the overall movement during the focusing process, thereby improving the focusing speed. At the same time, since the first lens group G1 and the fourth lens group G4 maintain the same relative position during the focusing process, the imaging error introduced by the lens movement can be reduced, ensuring the accuracy of focusing.

[0040] The combined focal length of the second lens group G2 and the third lens group G3 is further constrained by the conditional expression (1). It can be understood that if it is lower than the lower limit of the conditional expression (1), the refractive power of the second lens group G2 becomes smaller, and the movement amount of the second lens group G2 will increase during focusing, making it difficult to achieve miniaturization; and the spherical aberration generated by the third lens group G3 increases, making it difficult to correct the aberration of the entire lens system. If it is higher than the upper limit of the conditional expression (1), the refractive power of the third lens group G3 becomes smaller, and the movement amount of the third lens group G3 will increase during focusing, making it also difficult to achieve miniaturization; and the spherical aberration generated by the second lens group G2 increases, making it difficult to correct the aberration of the entire lens system.

[0041] Therefore, the large aperture full-frame photography lens provided by the present application can focus quickly and accurately while ensuring excellent optical performance, and can also realize lens miniaturization, with good portability and flexibility of use.

[0042] In some embodiments, a shape factor |Skp| of a lens having positive power in the first lens group G1 is ≤ 0.5, and a shape factor |Skm| of a lens having negative power in the first lens group G1 is ≤ 0.5.

[0043] The shape factor is one of the important factors controlling the imaging quality of the lens. By limiting the shape factor of the lens in the first lens group G1, the aberration and distortion caused by improper lens shape can be reduced, thereby improving the imaging clarity, contrast and color reproduction of the entire lens.

[0044] In this embodiment, Skp=(R1+R2) / (R1-R2); Skm=(R1+R2) / (R1-R2). Whether it is the calculation formula of the shape factor Skp of a lens with positive optical power or the calculation formula of the shape factor Skm of a lens with negative optical power, R1 represents the curvature radius of the lens surface facing the object side, and R2 represents the curvature radius of the lens surface facing the image side.

[0045] Specifically, in the first lens group G1, the shape factor conditional formula of the lens with negative optical power is mainly used to correct distortion and spherical aberration, and the shape factor conditional formula of the lens with positive optical power is mainly used to correct field curvature and coma. When Skp and Skm exceed their respective ranges, the effect of aberration correction will be affected.

[0046] In some embodiments, the first lens group G1 includes, from the object side to the image side, a first lens L01 having negative power, a second lens L02 having positive power, a third lens L03 having negative power, and a fourth lens L04 having positive power.

[0047] In this embodiment, a specific structural design of the first lens group G1 is proposed. The alternating arrangement of positive and negative optical powers helps to balance the optical power of the entire first lens group G1, thereby reducing aberrations and distortions within the first lens group G1 and improving imaging quality.

[0048] Furthermore, the second lens L02 and the third lens group G3 are combined into a first cemented lens. The design of the cemented lens can effectively reduce aberration problems such as chromatic aberration and spherical aberration, thereby improving the clarity and contrast of the image, and under the premise of achieving the same or similar optical performance, the use of the cemented lens can reduce the total number of lenses required, thereby making the lens structure more compact and simple.

[0049] In some embodiments, the Abbe number of the lens with positive refractive power in the second lens group G2 satisfies the range: 16≤Vd≤21.

[0050] The Abbe number is an important parameter to measure the dispersion ability of lens materials, reflecting the difference in the refractive index of the material for light of different wavelengths. The higher the Abbe number, the lower the dispersion ability of the material, that is, the smaller the color distortion when the lens forms an image.

[0051] In this embodiment, the Abbe number range of the lens with positive power in the second lens group G2 is limited. It can be understood that if the upper limit of the range is exceeded, the correction of the axial chromatic aberration and the change of the axial chromatic aberration during the focusing process will be difficult to correct; if the lower limit of the range is lower than the lower limit, the secondary dispersion of the axial chromatic aberration is easy to be over-corrected.

[0052] In some embodiments, the second lens group G2 includes, in order from the object side to the image side, a fifth lens L05 having positive refractive power and a sixth lens L06 having negative refractive power.

[0053] In this embodiment, a specific structural design of the second lens group G2 is proposed. The positive focal power of the fifth lens L05 is combined with the negative focal power of the sixth lens L06 to achieve a focal power balance in the second lens group G2. This reduces aberrations and distortions inside the second lens group G2 and improves imaging quality. Further, the fifth lens L05 and the sixth lens L06 are combined into a second cemented lens.

[0054] In some embodiments, the Abbe number of the lens with negative power in the third lens group G3 satisfies the range: 16≤Vd≤21.

[0055] In this embodiment, the Abbe number range of the lens with negative power in the third lens group G3 is limited. Similarly, if the upper limit of the range is exceeded, the correction of the axial chromatic aberration and the change of the axial chromatic aberration during the focusing process will be difficult to correct; if the lower limit of the range is below the lower limit, the secondary dispersion of the axial chromatic aberration is easily over-corrected.

[0056] In some embodiments, the third lens group G3 includes, from the object side to the image side, a seventh lens L07 having negative refractive power, an eighth lens L08 having positive refractive power, and a ninth lens L09 having positive refractive power.

[0057] In this embodiment, a specific structural design of the third lens group G3 is proposed. By combining the negative focal power of the seventh lens L07 with the positive focal power of the eighth lens L08 and the ninth lens L09, the focal power balance is achieved in the third lens group G3, aberrations and distortions are reduced, and imaging quality is improved. Furthermore, the seventh lens L07 and the eighth lens L08 are combined into a third cemented lens.

[0058] In some embodiments, an average refractive index of lenses in the fourth lens group G4 satisfies the range: 1.8≤Nd≤1.95.

[0059] The refractive index (Nd) of a lens is an important parameter that measures its ability to refract light. A lens with a high refractive index can refract light more efficiently, allowing the lens to achieve the same optical performance in a smaller volume.

[0060] In this embodiment, the average refractive index range of the lenses in the fourth lens group G4 is proposed. It is understandable that if it is lower than the lower limit of the conditional expression, the number of lenses in the fourth lens group G4 will increase, making it difficult to achieve miniaturization. If it is higher than the upper limit of the conditional expression, the optical glass with a high refractive index will have a large dispersion, making it difficult to correct the axial chromatic aberration.

[0061] In some embodiments, the fourth lens group G4 includes, from the object side to the image side, a tenth lens L10 having positive power, an eleventh lens L11 having negative power, a twelfth lens L12 having positive power, a thirteenth lens L13 having negative power, and a fourteenth lens L14 having negative power.

[0062] In this embodiment, a specific structural design of the fourth lens group G4 is proposed. The lens with positive focal power converges light, while the lens with negative focal power diverges light. Through reasonable matching, the entire fourth lens group G4 maintains stable focal power during the imaging process, which can reduce aberrations and distortions caused by sudden changes in focal power. Furthermore, the tenth lens L10 and the eleventh lens L11 are combined into a fourth cemented lens, and the twelfth lens L12 and the thirteenth lens L13 are combined into a fifth cemented lens.

[0063] In some embodiments, the large aperture full-frame photography lens further satisfies the conditional formula:

[0064] 0.3≤BFL / EFL≤1, (2);

[0065] Among them, BFL is the equivalent air distance from the image side of the last lens in the lens system to the image plane, and EFL is the focal length of the optical system in the infinite focus state.

[0066] In this embodiment, the BFL affects the overall length, back focal length and imaging quality of the lens; the EFL determines the viewing angle and imaging characteristics of the lens. Conditional formula (2) limits the ratio range between the BFL and the EFL, and within this ratio range, the design of the lens is balanced.

[0067] Specifically, when the value is below the lower limit of conditional expression (2), the back focal length corresponding to the focal length will be too short, making it difficult to design the mechanical structure on the imaging surface side; when the value is above the upper limit of conditional expression (2), the back focal length corresponding to the focal length will be too large, and the refractive power of each lens group will become smaller, making it difficult to correct the curvature of the image surface.

[0068] In the present application, a parallel glass plate GL configured by a filter is arranged between the last lens of the fourth lens group G4 and the image plane IMG. The parallel glass plate GL is used to filter light to improve the image quality. Specifically, the parallel glass plate GL can absorb or reflect light of certain wavelengths to eliminate or reduce interference factors such as chromatic aberration and stray light, thereby improving the contrast and clarity of the image.

[0069] Specific embodiments of the large aperture full-frame photography lens of the present application are presented below.

[0070] Example

[0071] Figure 1 The figure shows the structure of a large aperture full-frame photography lens. Figure 1As shown, in this embodiment, the first lens group G1 includes, from the object side to the image side, a first lens L01 with negative power, a second lens L02 with positive power, a third lens L03 with negative power, and a fourth lens L04 with positive power; wherein the second lens L02 and the third lens group G3 form a first cemented lens. The second lens group G2 includes, from the object side to the image side, a fifth lens L05 with positive power and a sixth lens L06 with negative power; wherein the fifth lens L05 and the sixth lens L06 form a second cemented lens. The third lens group G3 includes, from the object side to the image side, a seventh lens L07 with negative power, an eighth lens L08 with positive power, and a ninth lens L09 with positive power; wherein the seventh lens L07 and the eighth lens L08 form a third cemented lens. The fourth lens group G4 includes, from the object side to the image side, a tenth lens L10 with positive refractive power, an eleventh lens L11 with negative refractive power, a twelfth lens L12 with positive refractive power, a thirteenth lens L13 with negative refractive power and a fourteenth lens L14 with negative refractive power; wherein the tenth lens L10 and the eleventh lens L11 are combined into a fourth cemented lens, and the twelfth lens L12 and the thirteenth lens L13 are combined into a fifth cemented lens.

[0072] In this embodiment, the numerical data of the large aperture full-frame photography lens are shown in Tables 1 to 3:

[0073] Table 1

[0074]

[0075] Table 2

[0076]

[0077] Table 3

[0078]

[0079] The surface number indicates the surface number of each lens from the object side to the image side.

[0080] Figure 2 and Figure 3 axial chromatic aberration, field curvature and distortion curves of the embodiment when infinity is in focus, Figure 4 and Figure 5 Graphs showing axial chromatic aberration, field curvature and distortion of the embodiment when the embodiment is in focus at the closest distance.

[0081] The axial chromatic aberration curve shows the axial chromatic aberration curve when the aperture number is 1.47, where the F line, D line, and C line represent the axial chromatic aberration at wavelengths of 486nm, 587nm, and 656nm, respectively. The horizontal axis represents the spherical aberration value, and the vertical axis represents the field of view. The field curvature curve shows the field curvature curve when the half field angle ω is 14.02°, where the dotted line S represents the value of the chief ray D line on the sagittal image plane, the solid line T represents the value of the chief ray D line on the meridional image plane, the horizontal axis represents the field curvature value, and the vertical axis represents the field of view. The distortion curve shows the distortion curve when the half field angle ω is 14.02°, where the horizontal axis represents the distortion value, and the vertical axis represents the field of view.

[0082] As can be seen from Figures 2-5, the camera lens in this embodiment has a good imaging effect.

[0083] The present application also provides a photographic device. The photographic device includes an image sensor and the large aperture full-frame photographic lens as described above, wherein the image sensor and the large aperture full-frame photographic lens are detachably connected. The image sensor is a camera.

[0084] In this embodiment, the photographic device includes all technical solutions of all embodiments of the above-mentioned large aperture full-frame photographic lens, and therefore has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0085] The above description is only a partial or preferred embodiment of the present application. Neither the text nor the drawings can limit the scope of protection of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the overall concept of the present application, or direct / indirect application in other related technical fields are included in the scope of protection of the present application.

Claims

1. A large aperture full-frame photographic lens, characterized in that: The lens is composed of a first lens group with positive power, a second lens group with negative power, an aperture stop, a third lens group with positive power, and a fourth lens group with negative power from the object side to the image side in sequence; in the focusing process, the second lens group moves along the optical axis from the object side to the image side, the third lens group moves along the optical axis from the image side to the object side, and the positions of the first lens group and the fourth lens group relative to the image plane remain unchanged; The first lens group is composed of, from the object side to the image side, a first lens with negative optical power, a second lens with positive optical power, a third lens with negative optical power and a fourth lens with positive optical power; the second lens group is composed of, from the object side to the image side, a fifth lens with positive optical power and a sixth lens with negative optical power; the third lens group is composed of, from the object side to the image side, a seventh lens with negative optical power, an eighth lens with positive optical power and a ninth lens with positive optical power; the fourth lens group is composed of, from the object side to the image side, a tenth lens with positive optical power, an eleventh lens with negative optical power, a twelfth lens with positive optical power, a thirteenth lens with negative optical power and a fourteenth lens with negative optical power; The shape factor of the lens with positive power in the first lens group |Skp|≤0.5, Skp=(R1+R2) / (R1-R2); and the shape factor of the lens with negative power in the first lens group |Skm|≤0.5, Skm=(R1+R2) / (R1-R2); R1 represents the radius of curvature of the lens surface facing the object side, and R2 represents the radius of curvature of the lens surface facing the image side; A large aperture full-frame photography lens meets the following conditions: -3.6≤F2 / F3≤-0.6, (1); 0.3≤BFL / EFL≤1, (2); Among them, F2 represents the composite focal length of the second lens group, F3 represents the composite focal length of the third lens group, BFL is the equivalent air distance from the image side to the image plane of the last lens in the lens system, and EFL is the focal length of the optical system in the infinite focus state.

2. The large aperture full-frame photography lens according to claim 1, characterized in that: In the first lens group, the second lens and the third lens are combined into a first cemented lens.

3. The large aperture full-frame photography lens according to claim 1, characterized in that: The Abbe number of the lens with positive refractive power in the second lens group satisfies the range: 16≤Vd≤21.

4. The large aperture full-frame photography lens according to claim 3, characterized in that: In the second lens group, the fifth lens and the sixth lens are combined into a second cemented lens.

5. The large aperture full-frame photography lens according to claim 1, characterized in that: The Abbe number of the lens with negative power in the third lens group satisfies the range: 16≤Vd≤21.

6. The large aperture full-frame photography lens according to claim 5, characterized in that: In the third lens group, the seventh lens and the eighth lens are combined into a third cemented lens.

7. The large aperture full-frame photography lens according to claim 1, characterized in that: The average refractive index of the lenses in the fourth lens group satisfies the range of 1.8≤Nd≤1.

95.

8. The large aperture full-frame photography lens according to claim 7, characterized in that: In the fourth lens group, the tenth lens and the eleventh lens are combined into a fourth cemented lens, and the twelfth lens and the thirteenth lens are combined into a fifth cemented lens.

9. A photographic device, characterized in that: It comprises an image sensor and a large aperture full-frame photographic lens as claimed in any one of claims 1 to 8, wherein the image sensor is detachably connected to the large aperture full-frame photographic lens.

Images