An internal focusing photographic mirrorless lens
Patent Information
- Application Number
- CN202522446835.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-18
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-11-18
AI Technical Summary
[0005]为了克服现有技术因在半画幅微单上可使用的原厂配套镜头焦段范围仍有空缺尤其是广角焦段，且部分焦段的镜头价格昂贵，并不是所有摄影消费者都能接受的缺点，本实用新型提供一种内对焦摄影无反镜头，包括沿光轴从物侧至像侧依次排列具有负光焦度的第一透镜组、具有正光焦度的第二透镜组、光阑、具有正光焦度的第三透镜组、具有正光焦度的第四透镜组；第三透镜组为调焦组，第一透镜组满足：-2.1≤F1/F≤-1.9，其中F1表示第一透镜组的合成焦距，F表示整个光学成像系统的焦距
[0015]本实用新型的有益效果是：第一透镜组拥有合适的负光焦度来保证镜头拥有大口径广角视场，弥补的现有市场上原厂配套镜头广角焦段的空缺，同时兼顾镜头整体小型轻量使得成本降低，第一透镜组满足条件式：-2.1≤F1/F≤-1.9，第一透镜组拥有合理的视场角与后工作距离，光束在后组的入射高度处于合理区间。
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Figure CN224907124U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of photographic lenses, and more particularly to an internal focusing mirrorless photographic lens. Background Technology
[0002] A mirrorless camera is a type of interchangeable-lens digital camera without a mirror. Compared to a traditional DSLR camera, it eliminates the optical viewfinder and mirror structure, displaying the image captured by the sensor directly through an electronic viewfinder (EVF) or a screen. Mirrorless cameras are favored by photography enthusiasts and professional users alike due to their portability, high performance, and increasingly sophisticated lens options.
[0003] In recent years, thanks to the high performance and portability of mirrorless cameras, the number of users in the photography market has been increasing, and there are also diverse needs for various shooting scenarios.
[0004] There are still gaps in the range of original manufacturer lenses available for use on APS-C mirrorless cameras, especially in the wide-angle range, and some lenses in certain focal lengths are expensive, which is not affordable for all photography consumers. Utility Model Content
[0005] To overcome the shortcomings of existing technologies, such as the lack of available focal lengths for original factory-fitted lenses on APS-C mirrorless cameras, especially in the wide-angle range, and the high price of some lenses that are not affordable for all photography consumers, this utility model provides an internal focusing mirrorless camera lens, comprising a first lens group with negative optical power, a second lens group with positive optical power, an aperture stop, a third lens group with positive optical power, and a fourth lens group with positive optical power arranged sequentially along the optical axis from the object side to the image side; the third lens group is the focusing group, and the first lens group satisfies: -2.1≤F1 / F≤-1.9, where F1 represents the combined focal length of the first lens group, and F represents the focal length of the entire optical imaging system.
[0006] Optionally, 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 negative optical power, and a fifth lens with negative optical power.
[0007] Optionally, the second lens group includes a sixth lens with positive optical power and a seventh lens with negative optical power. The second lens group satisfies: -1.0≤F2 / F≤-0.7, where F2 represents the combined focal length of the second lens group and F represents the focal length of the optical imaging system.
[0008] Optionally, the third lens group includes an eighth lens with negative optical power, a ninth lens with positive optical power, and a tenth lens with negative optical power.
[0009] Optionally, the fourth lens group includes an eleventh lens with positive optical power, a twelfth lens with positive optical power, a thirteenth lens with positive optical power, and a fourteenth lens with negative optical power.
[0010] Optionally, the tenth lens in the third lens group moves along the optical axis, while the eighth and ninth lenses remain stationary relative to the image side.
[0011] Optionally, the third lens, the fourth lens, and the fifth lens form a three-layer laminated lens group.
[0012] Optionally, the thirteenth and fourteenth lenses are combined to form a cemented lens assembly.
[0013] Optionally, the Abbe number of the first lens is VDL1, and the refractive index is NDL1, satisfying the following relationships: 25≤VDL1≤30, 1.7≤NDL1≤1.75.
[0014] Optionally, the Abbe number of the second lens is VDL2, and the refractive index is NDL2, satisfying the following relationships: 50≤VDL2≤55, 1.7≤NDL2≤1.75.
[0015] The beneficial effects of this utility model are: the first lens group has a suitable negative optical power to ensure that the lens has a large aperture and wide-angle field of view, filling the gap in the wide-angle focal length of the original factory matching lens in the existing market, while taking into account the overall small size and light weight of the lens to reduce costs. The first lens group satisfies the condition: -2.1≤F1 / F≤-1.9. The first lens group has a reasonable field of view and back working distance, and the incident height of the beam in the back group is within a reasonable range. Attached Figure Description
[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0017] Figure 1 These are schematic diagrams of lens configurations in some embodiments; Figure 2 These are schematic diagrams of lens configurations and optical paths in some embodiments; Figure 3 These are schematic diagrams illustrating spherical aberration at infinity in some embodiments: Figure 4 These are schematic diagrams of field curvature at infinity in some embodiments; Figure 5 These are schematic diagrams illustrating distortion at infinity in some embodiments: Figure 6 These are schematic diagrams illustrating chromatic aberration at infinity focus in some embodiments. Figure 7 These are schematic diagrams illustrating spherical aberration when focusing at a distance of 1.5m in some embodiments: Figure 8 These are schematic diagrams of field curvature in some embodiments when focusing at a distance of 1.5m; Figure 9 These are schematic diagrams illustrating distortion when focusing at a distance of 1.5m in some embodiments: Figure 10 This is a schematic diagram of magnification chromatic aberration when focusing at a distance of 1.5m in some embodiments.
[0018] L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, eleventh lens; L12, twelfth lens; L13, thirteenth lens; L14, fourteenth lens; G1, first lens group; G2, second lens group; G3, third lens group; G4, fourth lens group; Detailed Implementation The following will clearly and completely describe the concept, specific structure, and technical effects of this utility model in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are all within the scope of protection of this utility model. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this utility model can be combined interactively without contradicting each other.
[0019] This invention provides an internal focusing mirrorless camera lens, used as a key optical imaging component in a mirrorless camera. It includes a first lens group G1 with negative optical power, a second lens group G2 with positive optical power, an aperture stop, a third lens group G3 with positive optical power, and a fourth lens group G4 with positive optical power, arranged sequentially along the optical axis from the object side to the image side. The third lens group G3 is a focusing group. The first lens group G1 satisfies the condition: -2.1≤F1 / F≤-1.9, where F1 represents the composite focal length of the first lens group G1, and F represents the focal length of the entire optical imaging system.
[0020] The first lens group has a suitable negative optical power to ensure that the lens has a large aperture and wide-angle field of view, filling the gap in the wide-angle focal length of the original factory-fitted lenses on the market. At the same time, it takes into account the overall small size and light weight of the lens to reduce costs. Specifically, the first lens group G1 satisfies the condition: -2.1≤F1 / F≤-1.9. The first lens group G1 has a reasonable field of view and back working distance, and the incident height of the beam in the back group is within a reasonable range.
[0021] If the condition satisfied by the first lens group G1 is lower than its lower limit, the optical power of the first lens group G1 decreases, and the divergence angle of the front group decreases. Although this reduces the burden on the relative aperture of the front and rear groups, it increases the overall length of the lens. If the condition satisfied by the first lens group G1 is higher than its upper limit, the optical power of the first lens group G1 increases, the divergence angle of the front group further increases, and the deflection angle of the rear group increases, thus increasing the burden on the relative aperture of the front and rear groups. Therefore, satisfying the above condition is the most reasonable.
[0022] In some embodiments, the first lens group G1 includes a first lens L1 with negative optical power, a second lens L2 with negative optical power, a third lens L3 with negative optical power, a fourth lens L4 with positive optical power, and a fifth lens with negative optical power. L5, the fifth lens with negative optical power.
[0023] Specifically, the first lens L1 is a concave-convex lens, the second lens L2 is a concave-convex lens, the third lens L3 is a concave lens, the fourth lens L4 is a convex lens, and the fifth lens... L5 is a concave-convex lens, the third lens L3, the fourth lens L4, and the fifth lens L5 forms a triple-cemented lens group. The first lens L1 has an Abbe number of VDL1 and a refractive index of NDL1, satisfying the following relationships: 25≤VDL1≤30 and 1.7≤NDL1≤1.75. The cemented lens group integrates three optical functions into one lens group, reducing the number of independent lenses in the lens, thereby reducing the size and weight of the lens.
[0024] In some embodiments, the second lens group G2 includes a sixth lens L6 with positive optical power and a seventh lens L7 with negative optical power. The second lens group G2 satisfies: -1.0≤F2 / F≤-0.7, where F2 represents the combined focal length of the second lens group G2, F represents the focal length of the optical imaging system, the Abbe number of the second lens L2 is VDL2, and the refractive index is NDL2, satisfying the relationships: 50≤VDL2≤55 and 1.7≤NDL2≤1.75.
[0025] Specifically, the sixth lens L6 and the seventh lens L7 are both concave-convex lenses. The second lens group G2 satisfies: -1.0 ≤ F2 / F ≤ -0.7, where F represents the focal length of the optical imaging system and F2 represents the composite focal length of the second lens group G2. Satisfying -1.0 ≤ F2 / F ≤ -0.7 allows the second lens group G2 to effectively correct off-axis astigmatism and coma, while simultaneously reducing the effective aperture of the light incident on the third lens group G3, thus reducing the aperture of the third lens group G3 and achieving the goal of reducing lens weight. If the expression satisfied by the second lens group G2 is lower than the lower limit, the reduced optical power of the second lens group G2 causes the radii of curvature of the negative lens surfaces S1 and S2 of the second lens group G2 to approach concentric circles, which is detrimental to manufacturing. If the value in the expression satisfied by the second lens group G2 is higher than the lower limit, the optical power of the second lens group G2 will increase, the incident angle of the edge rays will increase, and the distortion and astigmatism cannot be well corrected. Therefore, the second lens group G2 is most suitable if it satisfies: -1.0≤F2 / F≤-0.7.
[0026] In some embodiments, the third lens group G3 has an eighth lens L8 with negative optical power, a ninth lens L9 with positive optical power, and a tenth lens L10 with negative optical power.
[0027] Specifically, the eighth lens L8 is a concave-convex lens, the ninth lens L9 is a convex lens, and the tenth lens L10 is a concave lens. Furthermore, in the third lens group G3, the tenth lens L10 moves along the optical axis, while the eighth lens L8 and the ninth lens L9 remain stationary relative to the image side. The third lens group G3 is the focusing component in the optical imaging system. Within the third lens group G3, only the tenth lens L10 can move to achieve focusing. Using a single concave tenth lens L10 reduces the focusing travel distance, which helps to shorten the overall system length, reduce the weight of the focusing assembly and the load on the drive motor, and facilitates rapid focusing of the imaging lens and imaging equipment.
[0028] In some embodiments, the fourth lens group G4 includes an eleventh lens L11 with positive optical power, a twelfth lens L12 with positive optical power, a thirteenth lens L13 with positive optical power, and a fourteenth lens L14 with negative optical power.
[0029] Specifically, the eleventh lens L11 is a concave-convex lens, the twelfth lens L12 is a concave-convex lens, the thirteenth lens L13 is a convex lens, and the fourteenth lens L14 is a concave-convex lens. The thirteenth lens L13 and the fourteenth lens L14 are combined to form a cemented lens group.
[0030] Furthermore, the third and thirteenth lens elements are low-dispersion lenses, and the fifth and tenth lens elements are special-dispersion lenses, so that when the internal focusing mirrorless lens is used to shoot high-contrast images, it can minimize purple fringing or chromatic aberration at the edges of the subject.
[0031] Specifically, the third and thirteenth lenses are low-dispersion lenses with an Abbe number higher than 80 for light with a wavelength of 587.6nm. The fifth and tenth lenses are special dispersion lenses. The difference between special dispersion lenses and normal dispersion lenses is that normal dispersion lenses exhibit an increase in refractive index as the wavelength decreases, while special dispersion lenses exhibit an increase in refractive index as the wavelength increases, which facilitates dispersion correction of the visible spectrum.
[0032] Table 1 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:
[0033] Table 2 below lists the focusing data for this embodiment, including object distance, focal length, thickness of mirror 16 in Table 1, and thickness of mirror 18 in Table 1:
[0034] The above is a detailed description of the preferred embodiments of the present utility model. However, the present utility model is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present utility model. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.
Claims
1. A mirrorless camera lens with internal focusing, characterized in that, It includes a first lens group with negative optical power, a second lens group with positive optical power, an aperture, a third lens group with positive optical power, and a fourth lens group with positive optical power, arranged sequentially from the object side to the image side along the optical axis; the third lens group is the focusing group, and the first lens group satisfies: -2.1≤F1 / F≤-1.9, where F1 represents the combined focal length of the first lens group, and F represents the focal length of the entire optical imaging system.
2. The internal focusing mirrorless camera lens according to claim 1, characterized in that, 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 negative optical power, and a fifth lens with negative optical power.
3. The internal focusing mirrorless camera lens according to claim 1, characterized in that, The second lens group includes a sixth lens with positive optical power and a seventh lens with negative optical power. The second lens group satisfies: -1.0≤F2 / F≤-0.7, where F2 represents the combined focal length of the second lens group and F represents the focal length of the optical imaging system.
4. The internal focusing mirrorless lens according to claim 1, characterized in that, The third lens group has an eighth lens with negative optical power, a ninth lens with positive optical power, and a tenth lens with negative optical power.
5. The internal focusing mirrorless camera lens according to claim 1, characterized in that, The fourth lens group includes an eleventh lens with positive optical power, a twelfth lens with positive optical power, a thirteenth lens with positive optical power, and a fourteenth lens with negative optical power.
6. The internal focusing mirrorless camera lens according to claim 4, characterized in that, The tenth lens in the third lens group moves along the optical axis, while the eighth and ninth lenses remain stationary on the image side relative to each other.
7. The internal focusing mirrorless camera lens according to claim 2, characterized in that, The third, fourth, and fifth lenses together form a triple-laminated lens group.
8. The internal focusing mirrorless camera lens according to claim 5, characterized in that, The thirteenth and fourteenth lenses are combined to form a cemented lens group.
9. The internal focusing mirrorless camera lens according to claim 2, characterized in that, The first lens has an Abbe number of VDL1 and a refractive index of NDL1, satisfying the following relationships: 25≤VDL1≤30 and 1.7≤NDL1≤1.
75.
10. The internal focusing mirrorless lens according to claim 2, characterized in that, The second lens has an Abbe number of VDL2 and a refractive index of NDL2, satisfying the following relationships: 50≤VDL2≤55 and 1.7≤NDL2≤1.75.