Compact internal focusing wide-angle photographic lens

Abstract

The application provides a compact internal focusing wide-angle photographic lens, which comprises, in sequence from the object side to the image side along the optical axis, a first lens group with negative refractive power, an aperture stop, a second lens group with positive refractive power, and a third lens group with negative refractive power; during the focusing process from infinity to a close distance, the second lens group moves along the optical axis towards the object side; the first lens group contains at least two pieces of meniscus negative lenses, one of which is an aspheric lens, and satisfies the following condition formula: -7<F1 / F<-3, (1); the second lens group satisfies the following condition formula: 0.5<F2 / F<0.9, (2); wherein F represents the focal length of the photographic lens, F1 represents the combined focal length of the first lens group, and F2 represents the combined focal length of the second lens group. The application focuses by adopting the mode of internal single lens group movement, and good imaging quality and compact lens size are realized through reasonable optical design.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and more particularly to a compact, internally focused wide-angle photographic lens. Background Technology

[0002] In recent years, the demand for mirrorless cameras has been expanding rapidly in the photography market. Compared with the large size and poor portability of DSLR cameras, mirrorless cameras are smaller, lighter and more portable due to the elimination of the reflex mirror assembly. At the same time, thanks to the continuous development and maturity of high-precision CMOS chips, the resolution of cameras is also increasing day by day, enabling mirrorless cameras to have excellent high-quality imaging.

[0003] Currently, interchangeable camera lenses on the market generally suffer from problems such as large size, heavy weight, and poor portability in order to achieve high image quality. Prolonged use can lead to user fatigue. In particular, the domestic market lacks compact wide-angle camera lenses that can balance image quality and portability. To address this issue, this invention provides a compact internal focusing wide-angle camera lens. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies and market demands by providing a compact, internally focused wide-angle photographic lens. It offers excellent image quality, a compact size, and portability. It employs an internal single-lens-group focusing mechanism, resulting in fast focusing speed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A compact, internally focused wide-angle photographic lens comprises, along the optical axis from the object side to the image side: a first lens group with negative optical power, an aperture stop, a second lens group with positive optical power, and a third lens group with negative optical power; during the focusing process from infinity to close distance, the second lens group moves along the optical axis towards the object side, while the positions of the first and third lens groups relative to the image plane remain unchanged.

[0007] The first lens group comprises at least two meniscus negative lenses, one of which is an aspherical lens and satisfies the following condition:

[0008] -7 <F1 / F<-3,(1);

[0009] The second lens group satisfies the following condition:

[0010] 0.5 <F2 / F<0.9,(2);

[0011] Where F represents the focal length of the camera lens, F1 represents the combined focal length of the first lens group, and F2 represents the combined focal length of the second lens group.

[0012] As a preferred embodiment, the first lens group 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 arranged sequentially from the object side to the image side. The third lens and the fourth lens are combined to form a cemented lens group. The first lens and the second lens are meniscus negative lenses bent towards the image side. The third lens and the fifth lens are both ultra-low dispersion lenses.

[0013] As a preferred embodiment, the second lens is a plastic aspherical lens, and nd1 ≥ 1.65, where nd1 is defined as the refractive index of the second lens with respect to light with a wavelength of 587.6 nm.

[0014] As a preferred embodiment, the first lens group satisfies the following condition:

[0015] 61>|Vd2-Vd3|>28,(3);

[0016] Wherein, Vd2≥70, Vd2 is the Abbe number of the highest Abbe number lens in the first lens group with respect to light with a wavelength of 587.6nm; Vd3 is the Abbe number of the lowest Abbe number lens in the first lens group with respect to light with a wavelength of 587.6nm.

[0017] As a preferred embodiment, the second lens group comprises a sixth lens with positive optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power arranged sequentially from the object side to the image side. The sixth lens and the seventh lens are combined to form a cemented lens group, and the cementing surface of the cemented lens group is bent toward the aperture stop.

[0018] As a preferred embodiment, the sixth lens is a low-dispersion lens with nd4 ≤ 1.62, vd4 ≥ 60, and satisfies the following condition:

[0019] 60>|Vd4-Vd5|>33,(4);

[0020] Wherein, nd4 is defined as the refractive index of the sixth lens with respect to light with a wavelength of 587.6 nm, Vd4 is the Abbe number of the sixth lens with respect to light with a wavelength of 587.6 nm, and Vd5 is the Abbe number of the seventh lens with respect to light with a wavelength of 587.6 nm.

[0021] As a preferred embodiment, the eighth lens is a plastic aspherical lens.

[0022] As a preferred embodiment, the third lens group includes a ninth lens with negative optical power and a tenth lens with negative optical power arranged sequentially from the object side to the image side. The ninth lens is a meniscus negative lens bent towards the image side, and the tenth lens is a meniscus negative lens bent towards the object side.

[0023] As a preferred embodiment, the first lens group 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, a fifth lens with positive optical power, and an eleventh lens with negative optical power, arranged sequentially from the object side to the image side. The third and fourth lenses are combined to form a cemented lens group, and the fifth and eleventh lenses are combined to form a cemented lens group. The first and second lenses are meniscus negative lenses bent towards the image side, and the third lens is an ultra-low dispersion lens.

[0024] As a preferred embodiment, the first lens group satisfies the following condition:

[0025] |nd6-nd7|>0.2,(5);

[0026] |Vd6-Vd7|<1.5,(6);

[0027] Wherein, nd6 is defined as the refractive index of the fifth lens with respect to light with a wavelength of 587.6 nm, and nd7 is defined as the refractive index of the eleventh lens with respect to light with a wavelength of 587.6 nm; Vd6 is the Abbe number of the fifth lens with respect to light with a wavelength of 587.6 nm, and Vd7 is the Abbe number of the eleventh lens with respect to light with a wavelength of 587.6 nm.

[0028] Compared with the prior art, the present invention has the following technical effects:

[0029] This invention achieves an interchangeable wide-angle photographic lens with good image quality, compact size, easy portability, and fast focusing by designing a first lens group, a second lens group, and a third lens group.

[0030] To more clearly illustrate the structural features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of spherical aberration when focusing at infinity according to Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic diagram of the field curvature when focusing at infinity in Embodiment 1 of the present invention;

[0034] Figure 4 This is a schematic diagram of the distortion when focusing at infinity in Embodiment 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of spherical aberration at the closest focusing distance in Embodiment 1 of the present invention;

[0036] Figure 6 This is a schematic diagram of field curvature at the closest focusing distance in Embodiment 1 of the present invention;

[0037] Figure 7 This is a schematic diagram of distortion at the closest focusing distance in Embodiment 1 of the present invention;

[0038] Figure 8 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0039] Figure 9 This is a schematic diagram of spherical aberration when focusing at infinity according to Embodiment 2 of the present invention;

[0040] Figure 10 This is a schematic diagram of the field curvature when focusing at infinity in Embodiment 2 of the present invention;

[0041] Figure 11 This is a schematic diagram of distortion in embodiment 2 of the present invention when focusing at infinity;

[0042] Figure 12 This is a schematic diagram of spherical aberration at the closest focusing distance in Embodiment 2 of the present invention;

[0043] Figure 13 This is a schematic diagram of field curvature at the closest focusing distance in Embodiment 2 of the present invention;

[0044] Figure 14 This is a schematic diagram of distortion at the closest focusing distance in Embodiment 2 of the present invention;

[0045] Figure 15 This is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0046] Figure 16 This is a schematic diagram of spherical aberration in embodiment 3 of the present invention when focusing at infinity;

[0047] Figure 17 This is a schematic diagram of the field curvature when focusing at infinity in Embodiment 3 of the present invention;

[0048] Figure 18 This is a schematic diagram of the distortion when focusing at infinity in Embodiment 3 of the present invention;

[0049] Figure 19 This is a schematic diagram of spherical aberration at the closest focusing distance in Embodiment 3 of the present invention;

[0050] Figure 20 This is a schematic diagram of field curvature at the closest focusing distance in Embodiment 3 of the present invention;

[0051] Figure 21This is a schematic diagram of distortion at the closest focusing distance in Embodiment 3 of the present invention.

[0052] Explanation of reference numerals in the attached diagram:

[0053] G1, First lens group; STP, Aperture stop; G2, Second lens group; G3, Third lens group; IMG, Image plane;

[0054] L11, First lens; L12, Second lens; L13, Third lens; L14, Fourth lens; L15, Fifth lens; L16, Eleventh lens;

[0055] L21, sixth lens; L22, seventh lens; L23, eighth lens;

[0056] L31, the ninth lens; L32, the tenth lens. Detailed Implementation

[0057] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the indicated position or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0058] like Figure 1-21 As shown, a compact internal focusing wide-angle photographic lens comprises, along the optical axis from the object side to the image side: a first lens group G1 with negative optical power, an aperture stop STP, a second lens group G2 with positive optical power, and a third lens group G3 with negative optical power; during the focusing process from infinity to close distance, the second lens group G2 moves along the optical axis towards the object side, while the positions of the first lens group G1 and the third lens group G3 relative to the image plane IMG remain unchanged;

[0059] The first lens group G1 includes at least two meniscus negative lenses, one of which is an aspherical lens and satisfies the following condition:

[0060] -7 <F1 / F<-3,(1);

[0061] The second lens group G2 satisfies the following condition:

[0062] 0.5 <F2 / F<0.9,(2);

[0063] Where F represents the focal length of the camera lens, F1 represents the combined focal length of the first lens group G1, and F2 represents the combined focal length of the second lens group G2.

[0064] Example 1

[0065] Figure 1 The diagram shows a compact, internally focused wide-angle photographic lens structure according to Embodiment 1. In this embodiment, the first lens group G1 includes, sequentially arranged from the object side to the image side, a first lens L11 with negative optical power, a second lens L12 with negative optical power, a third lens L13 with negative optical power, a fourth lens L14 with positive optical power, and a fifth lens L15 with negative optical power. The third lens L13 and the fourth lens L14 are combined to form a cemented lens group. The first lens L11 and the second lens L12 are meniscus negative lenses bent towards the image side. The third lens L13 and the fifth lens L15 are both ultra-low dispersion lenses. The second lens L12 is a plastic aspherical lens, and nd1 ≥ 1.65, where nd1 is defined as the refractive index of the second lens L12 with respect to light with a wavelength of 587.6 nm. The first lens group G1 satisfies the following condition:

[0066] 61>|Vd2-Vd3|>28,(3);

[0067] Wherein, Vd2≥70, Vd2 is the Abbe number of the highest Abbe number lens in the first lens group G1 with respect to light with a wavelength of 587.6nm; Vd3 is the Abbe number of the lowest Abbe number lens in the first lens group G1 with respect to light with a wavelength of 587.6nm.

[0068] The second lens group G2 comprises a sixth lens L21 with positive optical power, a seventh lens L22 with negative optical power, and an eighth lens L23 with positive optical power, arranged sequentially from the object side to the image side. The sixth lens L21 and the seventh lens L22 form a cemented lens group, and the cementing surface of the cemented lens group is bent towards the aperture stop STP. The eighth lens L23 is a plastic aspherical lens. The sixth lens L21 is a low-dispersion lens with nd4 ≤ 1.62 and vd4 ≥ 60, and satisfies the following condition:

[0069] 60>|Vd4-Vd5|>33,(4);

[0070] Wherein, nd4 is defined as the refractive index of the sixth lens L21 with respect to light with a wavelength of 587.6 nm, Vd4 is the Abbe number of the sixth lens L21 with respect to light with a wavelength of 587.6 nm, and Vd5 is the Abbe number of the seventh lens L22 with respect to light with a wavelength of 587.6 nm.

[0071] The third lens group G3 includes a ninth lens L31 with negative optical power and a tenth lens L32 with negative optical power arranged sequentially from the object side to the image side. The ninth lens L31 is a meniscus negative lens that bends toward the image side, and the tenth lens L32 is a meniscus negative lens that bends toward the object side.

[0072] The numerical data of the camera lens in this embodiment 1 are shown in Tables 1, 2 and 3:

[0073] Table 1

[0074]

[0075]

[0076] Table 2

[0077]

[0078] Table 3

[0079]

[0080] Among them, the surface number indicates the surface number of each lens from the object side to the image side;

[0081] Figure 2-4 This is a graph showing the spherical aberration, field curvature, and distortion curves of Example 1 when focused at infinity. Figure 5-7 The graph shows the spherical aberration, field curvature, and distortion curves of Example 1 when the image is in focus at the closest distance.

[0082] The spherical aberration curves represent the spherical aberration curves at an aperture of f / 2.9. The F, D, and C lines represent the spherical aberrations at wavelengths of 486 nm, 587 nm, and 656 nm, respectively. The horizontal axis represents the magnitude of the spherical aberration, and the vertical axis represents the field of view. The field curvature curves represent the field of view at a half-field angle ω of 9.5. 0 The field curvature curve is shown, where the solid line S represents the value of the principal ray d-ray in the sagittal image plane, and the solid line T represents the value of the principal ray d-ray in the meridional image plane. The horizontal axis represents the magnitude of the field curvature value, and the vertical axis represents the field of view. The distortion curve diagram shows the field curvature at a half-field angle ω of 45.8°. 0 The distortion curve is shown, where the horizontal axis represents the distortion value and the vertical axis represents the field of view. The above descriptions of various spherical aberrations, field curvature, and distortion curves are the same as in other embodiments and will not be repeated below. Figure 2-7 It can be seen that the camera lens in this embodiment 1 has a good imaging effect.

[0083] Example 2

[0084] Figure 8 The diagram shown is a schematic of the compact internal focusing wide-angle photographic lens structure of Embodiment 2. The difference between Embodiment 2 and Embodiment 1 lies in the lens parameters. The numerical data of the photographic lens in this embodiment are shown in Tables 4, 5, and 6:

[0085] Table 4

[0086]

[0087]

[0088] Table 5

[0089]

[0090] Table 6

[0091]

[0092] Figure 9-11 This is a graph showing the spherical aberration, field curvature, and distortion curves when the image is focused at infinity in Example 2. Figure 12-14 Figures 9-14 show the spherical aberration, field curvature, and distortion curves of Example 2 at the closest focusing distance. As can be seen from Figures 9-14, the camera lens of this embodiment has good imaging performance.

[0093] Example 3

[0094] Figure 15 The diagram shown is a schematic of the compact internal focusing wide-angle photographic lens structure of Embodiment 3. The difference between Embodiment 3 and the previous embodiments, besides the different lens parameters, is that the first lens group G1 further includes an eleventh lens L16 with negative optical power, and the fifth lens L15 has positive optical power. The fifth lens L15 and the eleventh lens L16 are combined to form a cemented lens group. The eleventh lens L16 is located on the side of the fifth lens L15 near the aperture stop STP. The third lens L13 is an ultra-low dispersion lens, and the first lens group G1 satisfies the following condition:

[0095] |nd6-nd7|>0.2,(5);

[0096] |Vd6-Vd7|<1.5,(6);

[0097] Wherein, nd6 is defined as the refractive index of the fifth lens L15 with respect to light with a wavelength of 587.6 nm, and nd7 is defined as the refractive index of the eleventh lens L16 with respect to light with a wavelength of 587.6 nm; Vd6 is the Abbe number of the fifth lens L15 with respect to light with a wavelength of 587.6 nm, and Vd7 is the Abbe number of the eleventh lens L16 with respect to light with a wavelength of 587.6 nm.

[0098] The numerical data of the camera lens in this embodiment are shown in Tables 7, 8 and 9:

[0099] Table 7

[0100]

[0101]

[0102] Table 8

[0103]

[0104]

[0105] Table 9

[0106]

[0107] Figure 16-21 This is a graph showing the spherical aberration, field curvature, and distortion curves of Example 3 when focused at infinity. Figure 16-18 The figures 19-21 show the spherical aberration, field curvature, and distortion curves of Example 3 at the closest focusing distance. As can be seen from Figures 19-21, the compact internal focusing wide-angle lens of this embodiment has good imaging performance.

[0108] Table 10 is a summary of the calculated values ​​of conditions 1-4 and Vd for each embodiment:

[0109] Table 10

[0110]

[0111]

[0112] The foregoing has shown and described 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 embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A compact, internally focused wide-angle photographic lens characterized by comprising, in order from the object side, From the object side to the image side along the optical axis, the lens comprises in order: a first lens group with negative refractive power, an aperture stop, a second lens group with positive refractive power, and a third lens group with negative refractive power; the first lens group comprises, from the object side to the image side in order: a first lens with negative refractive power, a second lens with negative refractive power, a third lens with negative refractive power, and a fourth lens with positive refractive power, wherein the third lens and the fourth lens are combined into a cemented lens group, the first lens and the second lens are negative meniscus lenses bent toward the image side, and the third lens is an ultra-low dispersion lens; the second lens group comprises, from the object side to the image side in order: a sixth lens with positive refractive power, a seventh lens with negative refractive power, and an eighth lens with positive refractive power, wherein the sixth lens and the seventh lens are combined into a cemented lens group, and the cemented surface of the cemented lens group is bent toward the aperture stop; the third lens group comprises, from the object side to the image side in order: a ninth lens with negative refractive power and a tenth lens with negative refractive power, wherein the ninth lens is a negative meniscus lens bent toward the image side, and the tenth lens is a negative meniscus lens bent toward the object side; during the focusing process from infinity to a close distance, the second lens group moves toward the object side along the optical axis, and the first lens group and the third lens group remain unchanged relative to the image plane position. The first lens group comprises at least two negative meniscus lenses, one of which is an aspheric lens, and satisfies the following condition formula: -7 < F1 / F < -3, (1); The second lens group satisfies the following condition formula: 0.5 < F2 / F < 0.9, (2); wherein F represents the focal length of the photographic lens, F1 represents the combined focal length of the first lens group, and F2 represents the combined focal length of the second lens group.

2. The compact, internally focused wide-angle photographic lens of claim 1, wherein The first lens group further comprises a fifth lens with negative refractive power, which is arranged on the side of the fourth lens close to the image side, and the fifth lens is an ultra-low dispersion lens.

3. The compact, internally focused wide-angle photographic lens of claim 2, wherein The second lens is a plastic aspheric lens, and nd1 ≥ 1.65, wherein nd1 is defined as the refractive index of the second lens with respect to light of a wavelength of 587.6 nm.

4. The compact, internally focused wide-angle photographic lens of claim 2, wherein The first lens group satisfies the following condition formula: 61 > |Vd2-Vd3| > 28, (3); wherein Vd2 ≥ 70, Vd2 is the Abbe number of the highest Abbe number lens in the first lens group with respect to light of a wavelength of 587.6 nm, and Vd3 is the Abbe number of the lowest Abbe number lens in the first lens group with respect to light of a wavelength of 587.6 nm.

5. The compact, internally focused wide-angle photographic lens of claim 1, wherein The sixth lens is a low dispersion lens, nd4 ≤ 1.62, vd4 ≥ 60, and satisfies the following condition formula: 60 > |Vd4-Vd5| > 33, (4); wherein nd4 is defined as the refractive index of the sixth lens with respect to light of a wavelength of 587.6 nm, Vd4 is the Abbe number of the sixth lens with respect to light of a wavelength of 587.6 nm, and Vd5 is the Abbe number of the seventh lens with respect to light of a wavelength of 587.6 nm.

6. The compact, internally focused wide-angle photographic lens of claim 1, wherein The eighth lens is a plastic aspheric lens.

7. The compact, internally focused wide-angle photographic lens of claim 1, wherein The first lens group further includes, disposed in order from the object side to the image side, a fifth lens having positive refractive power and an eleventh lens having negative refractive power, the fifth lens being disposed on the side of the fourth lens closer to the image side.

8. The compact, internally focused wide-angle photographic lens of claim 7, wherein, The first lens group satisfies the following conditional expressions: |nd6-nd7|>0.2, (5); |Vd6-Vd7|<1.5, (6); where nd6 is defined as the refractive index of the fifth lens with respect to a light ray having a wavelength of 587.6 nm, nd7 is defined as the refractive index of the eleventh lens with respect to a light ray having a wavelength of 587.6 nm, Vd6 is the Abbe number of the fifth lens with respect to a light ray having a wavelength of 587.6 nm, and Vd7 is the Abbe number of the eleventh lens with respect to a light ray having a wavelength of 587.6 nm.

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