Large-aperture medium-format wide-angle automatic focusing lens and image pickup device

Abstract

The invention provides a large-aperture medium-format wide-angle automatic focusing lens and an image pickup device. The lens sequentially comprises a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with negative focal power, an aperture diaphragm, a fourth lens group with positive focal power and a fifth lens group with negative focal power from an object side to an image side, in the focusing process, the second lens group moves from the object side to the image side along the optical axis, and the fourth lens group moves from the image side to the object side along the optical axis. The lens satisfies the following conditional expressions: 0.5 < F1 / F < 2.5; f2 / F is greater than-3.5 and less than-2; 0.5 < F4 / F < 1.5; f / H is greater than 1 and less than 2.5. According to the scheme, better imaging quality can be realized under a larger aperture, so that the medium-format lens can adapt to large-aperture photography and video recording.

Description

Technical Field

[0001] The present invention relates to the field of camera technology, and in particular to a large aperture medium format wide angle automatic focusing lens and an image pickup device. Background Art

[0002] With the development of the photography industry, users have higher and higher demands on cameras. Even full-frame cameras cannot satisfy these high-end users' pursuit of ultimate photography, and they turn to medium-format cameras.

[0003] In the related art, due to the large size of the sensor of medium format cameras, there are some limitations in the lenses that match such cameras on the market. For example, although some lenses are short in length and high in resolution, their aperture is not large enough, and more exposure time is required for night shooting; or, other lenses are small in size and have high-performance optical image quality, but their aperture is also not large enough, resulting in poor adaptability of these lenses in specific environments. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a large aperture medium format wide angle autofocus lens and an image pickup device, aiming to solve the problem in the related art that medium format lenses are difficult to adapt to large aperture photography and videography.

[0005] In order to solve the above technical problems, the first aspect of the present invention provides a large aperture medium format wide angle autofocus lens, which comprises, from the object side to the image side, a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with negative optical power, an aperture stop, a fourth lens group with positive optical power, and a fifth lens group with negative optical power; During the focusing process, the second lens group moves along the optical axis from the object side to the image side, and the fourth lens group moves along the optical axis from the image side to the object side; The large aperture medium format wide angle autofocus lens satisfies the following conditional formula: 0.5<F1 / F<2.5; -3.5<F2 / F<-2; 0.5<F4 / F<1.5; 1<F / H<2.5; Among them, F1 is the synthetic focal length of the first lens group, F2 is the synthetic focal length of the second lens group, F4 is the synthetic focal length of the fourth lens group, F is the effective focal length of the lens at infinite working distance, and H is the half image height of the lens.

[0006] Optionally, at least two aspherical lenses are included in the lenses of the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group.

[0007] Optionally, during the focusing process, the first lens group, the third lens group, and the fifth lens group are fixed lens groups.

[0008] Optionally, the first lens group includes, from the object side to the image side, a first lens with negative optical power, a first optical element with positive optical power or negative optical power, and a fourth lens with positive optical power; Wherein, the first optical element comprises, from the object side to the image side, a second lens having negative optical power and a third lens having positive optical power, and the second lens and the third lens are combined into a cemented lens; or, The first optical element is a lens.

[0009] Optionally, the second lens group includes at least one lens with a refractive index Nd≥1.8.

[0010] Optionally, the second lens group includes a second optical element having negative optical power; Wherein, the second optical element comprises, from the object side to the image side, a fifth lens having positive power and a sixth lens having negative power, and the fifth lens and the sixth lens are combined into a cemented lens; or, The second optical element is a lens.

[0011] Optionally, the third lens group includes a third optical element having negative optical power; The third optical element includes a seventh lens and an eighth lens in order from the object side to the image side, one of the seventh lens and the eighth lens has a positive optical focal length, and the other has a negative optical focal length, and the seventh lens and the eighth lens are combined into a cemented lens; or The third optical element is a lens.

[0012] Optionally, the seventh lens and the eighth lens satisfy the following conditional formula: |Nd07-Nd08|<0.3; Wherein, Nd07 is the refractive index of the seventh lens, and Nd08 is the refractive index of the eighth lens.

[0013] Optionally, the fourth lens group includes at least one lens with an Abbe number Vd≥60.

[0014] Optionally, the fourth lens group includes, from the object side to the image side, a ninth lens having positive refractive power and a fourth optical element having positive refractive power; Wherein, the fourth optical element comprises, from the object side to the image side, a tenth lens having positive refractive power and an eleventh lens having negative refractive power, and the tenth lens and the eleventh lens are combined into a cemented lens; or, The fourth optical element is a lens.

[0015] Optionally, the fourth lens group includes, from the object side to the image side, a fifth optical element having positive refractive power and an eleventh lens having positive refractive power; Wherein, the fifth optical element comprises, from the object side to the image side, a ninth lens having negative optical power and a tenth lens having positive optical power, and the ninth lens and the tenth lens are combined into a cemented lens; or, The fifth optical element is a lens.

[0016] Optionally, the fifth lens group includes at least one lens with a refractive index Nd≥1.8.

[0017] Optionally, the fifth lens group includes, from the object side to the image side, a twelfth lens with positive refractive power, a thirteenth lens with negative refractive power, a fourteenth lens with negative refractive power, and a fifteenth lens with positive refractive power; Wherein, a refractive index Nd of at least one of the twelfth lens, the fourteenth lens, and the fifteenth lens is greater than or equal to 1.8.

[0018] Optionally, the fifth lens group includes, from the object side to the image side, a twelfth lens having positive power, a sixth optical element having negative power, and a fifteenth lens having negative power; Wherein, the sixth optical element comprises, from the object side to the image side, a thirteenth lens having positive refractive power and a fourteenth lens having negative refractive power, and the thirteenth lens and the fourteenth lens are combined into a cemented lens; or, The sixth optical element is a lens.

[0019] A second aspect of the present invention provides an image pickup device, comprising an image sensor and a large aperture medium format wide angle autofocus lens as described in any one of the above, wherein the image sensor is configured to receive an optical image formed by the large aperture medium format wide angle autofocus lens.

[0020] Compared with the related art, the large aperture medium format wide angle autofocus lens and image pickup device of the present invention have the following beneficial effects: by adjusting the size of the aperture diaphragm, the aperture value of the lens is controlled, thereby realizing large aperture photography and video recording; the second lens group moves along the optical axis from the object side to the image side, and the fourth lens group moves along the optical axis from the image side to the object side, that is, the second lens group and the fourth lens group move toward each other for focusing, so that the optical system of the entire lens can achieve better imaging quality at a larger aperture, so that the medium format lens can adapt to large aperture photography and video recording. Moreover, the lens can effectively correct various phase differences, such as spherical aberration, chromatic aberration and distortion, etc., improve the imaging quality, and ensure the clarity and sharpness of the picture while maintaining a larger aperture through the combination of positive, negative, negative, positive and negative lens groups. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a schematic structural diagram of a lens provided in Embodiment 1 of the present invention; Figure 2 is an axial chromatic aberration curve diagram of the lens provided by Embodiment 1 of the present invention when it is focused at infinity; Figure 3 Schematic diagram of field curvature and distortion of the lens provided by Embodiment 1 of the present invention when in focus at infinity; Figure 4 is an axial chromatic aberration curve diagram of the lens provided by Embodiment 1 of the present invention at the minimum focusing distance; Figure 5 is a schematic diagram of field curvature and distortion of the lens provided by Embodiment 1 of the present invention at the minimum focusing distance; Figure 6 is a schematic structural diagram of a lens provided in Embodiment 2 of the present invention; Figure 7 is an axial chromatic aberration curve diagram of the lens provided by Embodiment 2 of the present invention when in focus at infinity; Figure 8 is a schematic diagram of field curvature and distortion of the lens provided by Embodiment 2 of the present invention when the lens is focused at infinity; Fig. 9 is an axial chromatic aberration curve diagram of the lens provided by Embodiment 2 of the present invention at the minimum focusing distance; Fig.10 Schematic diagram of field curvature and distortion of the lens provided by Embodiment 2 of the present invention at the minimum focusing distance. DETAILED DESCRIPTION

[0023] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention. All other embodiments obtained by ordinary technicians in the field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "circumferential", "radial" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] Example: An embodiment of the present invention provides an image pickup device, comprising an image sensor and a large aperture medium format wide angle auto focus lens, wherein the image sensor is configured to receive an optical image formed by the large aperture medium format wide angle auto focus lens. Specifically, light reflected by the photographed object passes through the large aperture medium format wide angle auto focus lens to form an image and illuminate the photosensitive surface of the image sensor, the photosensitive surface of the image sensor receives the optical image and converts it into an image electrical signal output, thereby realizing the functions of the image pickup device such as taking pictures or taking videos; wherein the image sensor may be a charge coupled device, a complementary metal oxide semiconductor, etc., the image pickup device may be a camera, the camera module of the camera is detachably connected to the large aperture medium format wide angle auto focus lens, the camera module is provided with an image sensor, and when the camera module is connected to the large aperture medium format wide angle auto focus lens, the image sensor is located on the image side of the large aperture medium format wide angle auto focus lens.

[0027] See also Figure 1 and Figure 6, the large aperture medium format wide angle auto focus lens includes, from the object side to the image side, a first lens group G01 with positive focal power, a second lens group G02 with negative focal power, a third lens group G03 with negative focal power, an aperture stop STO, a fourth lens group G04 with positive focal power, and a fifth lens group G05 with negative focal power; in the focusing process, the second lens group G02 moves along the optical axis from the object side to the image side, and the fourth lens group G04 moves along the optical axis from the image side to the object side; the large aperture medium format wide angle auto focus lens satisfies the following conditional formula: 0.5<F1 / F<2.5, (1); -3.5<F2 / F<-2, (2); 0.5<F4 / F<1.5, (3); 1<F / H<2.5,(4); Among them, F1 is the composite focal length of the first lens group G01, F2 is the composite focal length of the second lens group G02, F4 is the composite focal length of the fourth lens group G04, F is the effective focal length of the lens at infinite working distance, and H is the half image height of the lens.

[0028] The technical solution of the present invention can control the aperture value of the lens by adjusting the size of the aperture stop STO, thereby realizing large aperture photography and video recording; the second lens group G02 moves along the optical axis from the object side to the image side, and the fourth lens group G04 moves along the optical axis from the image side to the object side, that is, the second lens group G02 and the fourth lens group G04 move toward each other for focusing, so that the optical system of the entire lens can achieve better imaging quality at a larger aperture, so that the medium format lens can adapt to large aperture photography and video recording. Moreover, the lens can effectively correct various phase differences, such as spherical aberration, chromatic aberration and distortion, etc., improve the imaging quality, and ensure the clarity and sharpness of the picture while maintaining a larger aperture.

[0029] In addition, the second lens group G02 is designed to move along the optical axis from the object side to the image side, and the fourth lens group G04 is designed to move along the optical axis from the image side to the object side. This relative motion focusing method is called "inner focusing", which can reduce the change in the total length of the lens during the focusing process, making the focusing speed faster and smoother.

[0030] It should be noted that the first lens group G01 has positive focal power, which is used to collect and preliminarily focus light. The second lens group G02 and the fourth lens group G04 can move along the optical axis during the autofocus process to adjust the focal position. The third lens group G03 and the fifth lens group G05 have negative focal power, which can further correct the light and improve the imaging quality. The aperture stop STO is used to control the amount of light entering the lens, thereby adjusting the exposure and depth of field.

[0031] It should be understood that by satisfying the specific conditional equations (1), (2), (3) and (4), the proportional relationship between the composite focal length of each lens group and the effective focal length of the lens, and between the effective focal length of the lens and the half-height is defined, so that the lens structure can be optimized to achieve a compact design, thereby improving the imaging quality and focusing performance of the lens.

[0032] Specifically, setting conditional formula (1) to limit the relationship between the synthetic focal length of the first lens group G01 and the effective focal length of the lens at infinite working distance is helpful to balance light collection and imaging quality. Exceeding the upper limit of the range will make the length of the entire first lens group G01 longer, which will reduce the tolerance sensitivity, but is not conducive to the miniaturization of the lens; below the lower limit of the range, it is conducive to reducing the size and weight of the first lens group G01, but will increase the tolerance sensitivity, which is not conducive to the assembly of the lens. For example, the value of F1 / F can be 0.6, 1, 1.4, 1.8, 2, 2.4, etc.

[0033] Conditional formula (2) is set to define the relationship between the synthetic focal length of the second lens group G02 and the effective focal length of the lens at infinite working distance, reflecting the focal length variation range of the second lens group G02 in lens design. Exceeding the upper limit of the range is not conducive to the correction of chromatic aberration of the lens optical system; below the lower limit of the range, the focusing stroke will be increased, and it is not conducive to the miniaturization of the lens. For example, the value of F2 / F can be -3.45, -3.22, -3, -2.9, -2.5, -2.2, etc.

[0034] Conditional formula (3) is set to define the relationship between the synthetic focal length of the fourth lens group G04 and the effective focal length of the lens at infinite working distance, reflecting the focal length variation range of the fourth lens group G04 in lens design. Exceeding the upper limit of the range is not conducive to the miniaturization of the lens; being lower than the lower limit of the range is not conducive to the correction of chromatic aberration and will increase the sensitivity of the assembly. For example, the value of F4 / F can be 0.55, 0.6, 0.8, 1, 1.2, 1.45, etc.

[0035] Setting conditional equation (4) limits the relationship between the effective focal length of the lens at infinite working distance and the half image height of the lens, which reflects the relationship between the focal length of the lens and the image size, that is, the longer the focal length, the smaller the image (under the same sensor size). If the upper limit of the range is exceeded, the field of view angle becomes smaller, which limits the shooting range; if the lower limit of the range is exceeded, the field of view angle becomes larger, which is not conducive to the correction of lens distortion and will cause the captured image to be distorted. For example, the value of F / H can be 1.1, 1.6, 2, 2.2, 2.4, 2.45, etc.

[0036] In some embodiments, during the focusing process, the first lens group G01, the third lens group G03, and the fifth lens group G05 are fixed lens groups, that is, the positions of the first lens group G01, the third lens group G03, and the fifth lens group G05 relative to the image plane IMG remain unchanged, so that the first lens group G01, the third lens group G03, and the fifth lens group G05 remain relatively fixed during the focusing process, which helps to maintain the overall stability of the lens and imaging consistency.

[0037] See also Figure 1 and Figure 6 In some embodiments, the first lens group G01 includes, from the object side to the image side, a first lens L01 with negative optical power, a first optical element with positive optical power or negative optical power, and a fourth lens L04 with positive optical power. This arrangement of multiple lenses can achieve high-quality imaging effects, including high definition, low aberration, low distortion, and low dispersion. Among them, the first optical element includes, from the object side to the image side, a second lens L02 with negative optical power and a third lens L03 with positive optical power. The second lens L02 and the third lens group G03 are combined into a cemented lens; or, the first optical element is a single lens. Compared with the arrangement of the first optical element as two independent lenses, the size and weight of the lens can be reduced, making the lens more compact and portable.

[0038] It should be noted that a cemented lens is a single lens assembly formed by bonding two or more lenses together with an optical cement. Since lenses made of different materials have different degrees of dispersion of light, by selecting a suitable combination of materials, a cemented lens can effectively correct chromatic aberration and improve the color reproduction of imaging, so it has the performance of correcting chromatic aberration; and the cemented lens eliminates the air gap between the lenses, reduces the reflection and scattering caused by the air gap, and improves the contrast of the imaging; and by combining multiple lenses into a cemented lens, the structure of the lens can be simplified, the number and weight of the lenses can be reduced, and the lens can be made more compact and lightweight.

[0039] The lens design of the first lens group G01 is described below with examples.

[0040] See also Figure 1 In a specific example, the first lens group G01 includes, from the object side to the image side, a first lens L01 with negative optical power, a second lens L02 with negative optical power, a third lens L03 with positive optical power, and a fourth lens L04 with positive optical power; wherein the second lens L02 and the third lens group G03 are combined into a cemented lens with negative optical power.

[0041] See also Figure 6In a specific example, the first lens group G01 includes, from the object side to the image side, a first lens L01 with negative optical power, a second lens L02 with negative optical power, a third lens L03 with positive optical power, and a fourth lens L04 with positive optical power; wherein the second lens L02 and the third lens group G03 are combined into a cemented lens with positive optical power.

[0042] The two specific structural designs of the lenses of the first lens group G01 are proposed above, both of which are based on a combination of four lenses. By configuring different optical power combinations, they can provide better imaging effects in specific application scenarios to meet specific optical design requirements.

[0043] In some embodiments, the second lens group G02 includes at least one lens with a refractive index Nd ≥ 1.8, that is, the second lens group G02 includes at least one high-refractive index lens, which can achieve a smaller volume and higher imaging quality for the second lens group G02. For example, the second lens group G02 may include one high-refractive index lens, or the second lens group G02 may include two high-refractive index lenses, and the refractive index Nd of the high-refractive index lens may be 1.8, 1.82, 1.85, 1.88, 1.9, 1.95, etc.

[0044] It should be noted that the refractive index is a physical quantity that describes the degree to which the propagation direction of light changes when it propagates from one medium to another. In optical lens design, materials with a high refractive index can make the lens thinner while maintaining the same focal length and optical performance, which means that the use of high refractive index materials helps to achieve a more compact lens design and reduce the size and weight of the lens. In addition, high refractive index lenses are also beneficial for eliminating spherical aberration and correcting chromatic aberration.

[0045] See also Figure 1 and Figure 6 In some embodiments, the second lens group G02 includes a second optical element with negative power; wherein the second optical element includes a fifth lens L05 with positive power and a sixth lens L06 with negative power in order from the object side to the image side, and the fifth lens L05 and the sixth lens L06 are combined into a cemented lens; or, the second optical element is a single lens. Compared with the configuration in which the second optical element is two independent lenses, the size and weight of the lens can be reduced, making the lens more compact and portable, and it is also conducive to realizing the rapid movement of the second lens group G02.

[0046] The lens design of the second lens group G02 is described below with examples.

[0047] See also Figure 1 and Figure 6In a specific example, the second lens group G02 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 are combined into a cemented lens with negative power, and the refractive index Nd of the fifth lens L05 is ≥ 1.8. In this specific example, the second lens group G02 has only two lenses, one of which is a high refractive index lens, and the two lenses are designed with positive and negative power and combined into a cemented lens, which can not only optimize aberration correction and dispersion control, improve imaging quality, but also greatly reduce the volume of the focusing group, so that the focus can be quickly in place.

[0048] It should be noted that, in other specific examples, the refractive index Nd of the fifth lens L05 and the sixth lens L06 may be set to be greater than or equal to 1.8, or the refractive index Nd06 of the sixth lens L06 may be set to be greater than or equal to 1.8.

[0049] See also Figure 1 and Figure 6 In some embodiments, the third lens group G03 includes a third optical element with negative optical power; wherein the third optical element includes a seventh lens L07 and an eighth lens L08 in order from the object side to the image side, one of the seventh lens L07 and the eighth lens L08 has positive optical power and the other has negative optical power, and the seventh lens L07 and the eighth lens L08 are combined into a cemented lens; or, the third optical element is a single lens. The lens design of the third lens group G03 can provide better imaging effects in specific application scenarios by configuring different optical power combinations, so as to meet specific optical design requirements.

[0050] The lens design of the third lens group G03 is described below with examples.

[0051] See also Figure 1 In a specific example, the third lens group G03 includes, from the object side to the image side, a seventh lens L07 with positive optical power and an eighth lens L08 with negative optical power; wherein the seventh lens L07 and the eighth lens L08 are combined into a cemented lens with negative optical power.

[0052] See also Figure 6 In another specific example, the third lens group G03 includes, from the object side to the image side, a seventh lens L07 with negative optical power and an eighth lens L08 with positive optical power; wherein the seventh lens L07 and the eighth lens L08 are combined into a cemented lens with negative optical power.

[0053] The above two specific structural designs of the lens of the third lens group G03 are both based on the combination of two lenses. Combining the seventh lens L07 and the eighth lens L08 into a cemented lens setting can further reduce the number of lenses, simplify the lens structure, and make the lens more compact and portable; moreover, the seventh lens L07 and the eighth lens L08 are designed with positive and negative optical power, which can optimize aberration correction and dispersion control and improve imaging quality.

[0054] Furthermore, the seventh lens L07 and the eighth lens L08 in the above embodiment satisfy the following conditional formula: |Nd07-Nd08|<0.3, (5); Wherein, Nd07 is the refractive index of the seventh lens L07, and Nd08 is the refractive index of the eighth lens L08.

[0055] It should be understood that since the seventh lens L07 and the eighth lens L08 are combined into a cemented lens, when light passes through the cemented lens, the uneven distribution of refractive index will cause spherical aberration when the light is focused, thereby affecting the imaging quality.

[0056] Specifically, conditional formula (5) defines the relationship between the refractive index of the seventh lens L07 and the refractive index of the eighth lens L08, and reflects the refractive index distribution of the cemented lens composed of the seventh lens L07 and the eighth lens L08. When it is greater than or equal to the upper limit of this range, it will be difficult to control the spherical aberration of the lens optical system. For example, the value of |Nd07-Nd08| can be 0.298, 0.29, 0.285, 0.28, 0.2, 0.1, etc.

[0057] In some embodiments, the fourth lens group G04 includes at least one lens with an Abbe number Vd ≥ 60, that is, the fourth lens group G04 includes at least one high Abbe number lens, which can reduce chromatic aberration and avoid blur and color distortion caused by chromatic aberration, especially at the edge and wide-angle part, thereby further improving the imaging quality of the lens. For example, the fourth lens group G04 includes one high Abbe number lens, or the fourth lens group G04 includes two high Abbe number lenses, etc.; the Abbe number Vd of the high Abbe number lens can be 60, 61, 62, 63, 64, 65, etc.

[0058] It should be noted that the Abbe number is a parameter that describes the dispersion ability of a material. A high Abbe number means that the material has less dispersion. In photographic lenses, dispersion is one of the main factors that cause color fringes to appear at the edge of the image (i.e., the "dispersion" phenomenon). Especially at large apertures, the dispersion phenomenon will be more obvious due to the large refraction angle of light in the lens. By using a lens with a high Abbe number, this dispersion phenomenon can be significantly reduced, making the lens' imaging consistency better under different colors and improving image clarity and contrast.

[0059] The lens design of the fourth lens group G04 is described below with examples.

[0060] See also Figure 1 In some embodiments, the fourth lens group G04 includes, from the object side to the image side, a ninth lens L09 having positive power and a fourth optical element having positive power; wherein the fourth optical element includes, from the object side to the image side, a tenth lens L10 having positive power and an eleventh lens L11 having negative power, and the tenth lens L10 and the eleventh lens L11 are combined into a cemented lens; or, the fourth optical element is a single lens. The Abbe number Vd of at least one of the ninth lens L09 and the tenth lens L10 with respect to light having a wavelength of 587.6 nm is ≥ 60.

[0061] Please continue reading Figure 1 In a specific example, the fourth lens group G04 includes, from the object side to the image side, a ninth lens L09 having positive power, a tenth lens L10 having positive power, and an eleventh lens L11 having negative power. The tenth lens L10 and the eleventh lens L11 are combined into a cemented lens having positive power, and the Abbe numbers Vd of the ninth lens L09 and the tenth lens L10 are ≥ 60.

[0062] It should be noted that, in other specific examples, the Abbe number Vd09 of the ninth lens L09 may be set to be ≥60, or the Abbe number Vd10 of the tenth lens L10 may be set to be ≥60, etc.

[0063] See also Figure 6 The fourth lens group G04 includes, from the object side to the image side, a fifth optical element with positive power and an eleventh lens L11 with positive power; wherein the fifth optical element includes, from the object side to the image side, a ninth lens L09 with negative power and a tenth lens L10 with positive power, and the ninth lens L09 and the tenth lens L10 are combined into a cemented lens; or, the fifth optical element is a single lens. The Abbe number Vd of at least one of the tenth lens L10 and the eleventh lens L11 with respect to light having a wavelength of 587.6 nm is ≥ 60.

[0064] Please continue reading Figure 6 In a specific example, the fourth lens group G04 includes, from the object side to the image side, a ninth lens L09 having negative power, a tenth lens L10 having positive power, and an eleventh lens L11 having positive power. The ninth lens L09 and the tenth lens L10 are combined into a cemented lens having positive power, and the Abbe numbers Vd of the tenth lens L10 and the eleventh lens L11 are ≥60.

[0065] It should be noted that, in other specific examples, the Abbe number Vd11 of the eleventh lens L11 may be set to be ≥60, or the Abbe number Vd10 of the tenth lens L10 may be set to be ≥60, etc.

[0066] The above two specific structural designs of the lens of the fourth lens group G04 are both based on a combination of three lenses. By configuring different combinations of optical focal lengths, they can provide better imaging effects in specific application scenarios to meet specific optical design requirements. Moreover, the setting based on the high Abbe number lens can improve the imaging quality of the lens; the setting based on the combined cemented lens can not only reduce the size and weight of the lens, making the lens more compact and portable, but also greatly reduce the size of the focus group, so that the focus can be quickly in place.

[0067] In some embodiments, the fifth lens group G05 includes at least one lens with a refractive index Nd ≥ 1.8, that is, the fifth lens group G05 includes at least one high-refractive index lens, which can achieve a smaller volume and higher imaging quality for the fifth lens group G05. For example, the fifth lens group G05 can include one high-refractive index lens, or the fifth lens group G05 can include two high-refractive index lenses, etc. The refractive index Nd of the high-refractive index lens can be 1.8, 1.82, 1.85, 1.88, 1.9, 1.95, etc.

[0068] The lens design of the fifth lens group G05 is described below with examples.

[0069] See also Figure 1 In a specific example, the fifth lens group G05 includes, from the object side to the image side, a twelfth lens L12 with positive power, a thirteenth lens L13 with negative power, a fourteenth lens L14 with negative power, and a fifteenth lens L15 with positive power; wherein the refractive index Nd of the twelfth lens L12, the fourteenth lens L14, and the fifteenth lens L15 is ≥1.8.

[0070] According to actual needs, in other specific examples, the refractive index Nd12 of the twelfth lens L12 may be set to be ≥1.8, or the refractive index Nd of the fourteenth lens L14 and the fifteenth lens L15 may be set to be ≥1.8, etc.

[0071] See also Figure 6In some embodiments, the fifth lens group G05 includes, from the object side to the image side, a twelfth lens L12 with positive power, a sixth optical element with negative power, and a fifteenth lens L15 with negative power; wherein the sixth optical element includes, from the object side to the image side, a thirteenth lens L13 with positive power and a fourteenth lens L14 with negative power, and the thirteenth lens L13 and the fourteenth lens L14 are combined into a cemented lens; or, the sixth optical element is a single lens. The refractive index Nd of at least one of the twelfth lens L12 and the fifteenth lens L15 is ≥ 1.8.

[0072] Please continue reading Figure 6 In a specific example, the fifth lens group G05 includes, from the object side to the image side, a twelfth lens L12 having positive power, a thirteenth lens L13 having positive power, a fourteenth lens L14 having negative power, and a fifteenth lens L15 having negative power. The thirteenth lens L13 and the fourteenth lens L14 are combined into a cemented lens having negative power, and the refractive index Nd of the twelfth lens L12 and the fifteenth lens L15 is ≥1.8.

[0073] According to actual needs, the refractive index Nd12 of the twelfth lens L12 may be set to be ≥1.8, or the refractive index Nd of the fourteenth lens L14 and the fifteenth lens L15 may be set to be ≥1.8, etc.

[0074] The above two specific structural designs of the fifth lens group G05 are proposed. Based on the combination of multiple lenses, different combinations of optical powers are configured to provide better imaging effects in specific application scenarios to meet specific optical design requirements. Moreover, based on the setting of high refractive index lenses, the imaging quality of the lens can be improved; based on the setting of combined cemented lenses, not only can the size and weight of the lens be reduced, making the lens more compact and portable, but also the mechanical stability and reliability of the lens can be improved.

[0075] See also Figure 1 and Figure 6 In some embodiments, at least two aspheric lenses are included in the lenses of the first lens group G01, the second lens group G02, the third lens group L03, the fourth lens group G04, and the fifth lens group G05, which can effectively shorten the length of the system and improve the imaging quality. For example, the first lens group G01 and the fifth lens group G05 are each provided with an aspheric lens, or the fifth lens group G05 is provided with two aspheric lenses, or the first lens group G01 is provided with two aspheric lenses and the fifth lens group G05 is provided with one aspheric lens.

[0076] It should be noted that aspherical lenses are relative to traditional spherical lenses. Traditional spherical lenses are relatively simple in design and manufacturing, but because the radius of curvature of their surfaces is constant, this will cause aberrations when light passes through the lenses, especially at the edges. Aspherical lenses modify the curvature of the lens surface so that light can pass through the lenses more evenly, thereby effectively reducing or eliminating these aberrations, making the image edges clearer, improving sharpness, and making the focus more accurate, thereby achieving high-quality imaging at large apertures. Therefore, aspherical lenses can achieve large apertures and improve sharpness. When designing lenses, aspherical lenses can also be used to reduce the number and thickness of lenses, thereby reducing the size and weight of the lenses.

[0077] See also Figure 1 and Figure 6 In some embodiments, a parallel glass plate GL configured by a filter is arranged between the last lens of the fifth lens group G05 and the image plane IMG. The parallel glass plate GL is used to filter light to improve the image quality. Specifically, it 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.

[0078] The following is a specific embodiment of a large aperture medium format wide angle autofocus lens.

[0079] Example 1 See also Figure 1 , Figure 1: is a schematic diagram of the structure of a large aperture medium format wide-angle autofocus lens provided in this embodiment. The first lens group G01 includes, from the object side to the image side, a first lens L01 with negative optical power, a second lens L02 with negative optical power, a third lens L03 with positive optical power, and a fourth lens L04 with positive optical power; wherein the second lens L02 and the third lens group G03 are combined into a cemented lens with negative optical power, and the fourth lens L04 is an aspherical lens. The second lens group G02 includes, from the object side to the image side, a fifth lens L05 with positive optical power and a sixth lens L06 with negative optical power; wherein the fifth lens L05 and the sixth lens L06 are combined into a cemented lens with negative optical power, and the refractive index Nd of the fifth lens L05 is 1.92. The third lens group G03 includes, from the object side to the image side, a seventh lens L07 with positive power and an eighth lens L08 with negative power; wherein the seventh lens L07 and the eighth lens L08 are combined into a cemented lens with negative power, the refractive index Nd07 of the seventh lens L07 is 1.59, and the refractive index Nd08 of the eighth lens L08 is 1.67. The fourth lens group G04 includes, from the object side to the image side, a ninth lens L09 with positive power, a tenth lens L10 with positive power, and an eleventh lens L11 with negative power; wherein the tenth lens L10 and the eleventh lens L11 are combined into a cemented lens with positive power, the Abbe number Vd of the ninth lens L09 is 68.62, and the Abbe number Vd of the tenth lens L10 is 68.62. The aperture stop STO is located between the eighth lens L08 and the ninth lens L09. The fifth lens group G05 includes, from the object side to the image side, a twelfth lens L12 with positive power, a thirteenth lens L13 with negative power, a fourteenth lens L14 with negative power, and a fifteenth lens L15 with positive power; wherein, the refractive index Nd of the twelfth lens L12 is 1.95, the refractive index Nd of the fourteenth lens L14 is 1.81, the refractive index Nd of the fifteenth lens L15 is 1.83, and the fourteenth lens L14 is an aspherical lens.

[0080] In this embodiment, the numerical data of the large aperture medium format wide angle auto focus lens are shown in Table 1 and Table 2: Table 1

[0081] Table 2

[0082] The surface number indicates the surface number of each lens from the object side to the image side.

[0083] See also Figures 2 to 5 , Figure 2This is the axial chromatic aberration curve when the lens is focused at infinity. Figure 3 This is a schematic diagram of field curvature and distortion when the lens is focused at infinity. Figure 4 It is the axial chromatic aberration curve of the lens at the closest focusing distance. Figure 5 This is a schematic diagram of the field curvature and distortion of the lens at the closest focusing distance. Figures 2 to 5 It can be seen that the lens of Example 1 has a good imaging effect.

[0084] It should be noted that the axial chromatic aberration curve diagram represents the axial chromatic aberration curve when the aperture number is 1.47, wherein the F line, D line, and C line represent the axial chromatic aberration at a wavelength of 486nm, a wavelength of 587nm, and a wavelength of 656nm, respectively. The horizontal axis represents the spherical aberration value, and the vertical axis represents the field of view. The field curvature curve diagram represents the field curvature curve when the half field angle ω is 14.02°, wherein 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 diagram represents the distortion curve when the half field angle ω is 14.02°, wherein the horizontal axis represents the distortion value, and the vertical axis represents the field of view.

[0085] It should be understood that the above descriptions of various spherical aberrations, field curvatures, and distortion curves are the same as those in other embodiments and will not be repeated in detail below.

[0086] Example 2 See also Figure 6 , Figure 6: is a schematic diagram of the structure of a large aperture medium format wide-angle autofocus lens provided in this embodiment. The first lens group G01 includes, from the object side to the image side, a first lens L01 with negative optical power, a second lens L02 with negative optical power, a third lens L03 with positive optical power, and a fourth lens L04 with positive optical power; wherein the second lens L02 and the third lens group G03 are combined into a cemented lens with positive optical power, and the fourth lens L04 is an aspherical lens. The second lens group G02 includes, from the object side to the image side, a fifth lens L05 with positive optical power and a sixth lens L06 with negative optical power; wherein the fifth lens L05 and the sixth lens L06 are combined into a cemented lens with negative optical power, and the refractive index Nd of the fifth lens L05 is 1.95. The third lens group G03 includes, from the object side to the image side, a seventh lens L07 with negative power and an eighth lens L08 with positive power; wherein the seventh lens L07 and the eighth lens L08 are combined into a cemented lens with negative power, the refractive index Nd07 of the seventh lens L07 is 1.67, and the refractive index Nd08 of the eighth lens L08 is 1.59. The fourth lens group G04 includes, from the object side to the image side, a ninth lens L09 with negative power, a tenth lens L10 with positive power, and an eleventh lens L11 with positive power; wherein the ninth lens L09 and the tenth lens L10 are combined into a cemented lens with positive power, the Abbe number Vd of the tenth lens L10 is 68.62, and the Abbe number Vd of the eleventh lens L11 is 68.62. The aperture stop STO is provided between the eighth lens L08 and the ninth lens L09. The fifth lens group G05 includes, from the object side to the image side, a twelfth lens L12 with positive power, a thirteenth lens L13 with positive power, a fourteenth lens L14 with negative power, and a fifteenth lens L15 with negative power; wherein the thirteenth lens L13 and the fourteenth lens L14 are combined into a cemented lens with negative power, the refractive index Nd of the twelfth lens L12 is 1.95, the refractive index Nd of the fifteenth lens L15 is 1.85, and the fifteenth lens L15 is an aspherical lens.

[0087] In this embodiment, the numerical data of the large aperture medium format wide angle auto focus lens are shown in Table 3 and Table 4: Table 3

[0088] Table 4

[0089] The surface number indicates the surface number of each lens from the object side to the image side.

[0090] See also Figures 7 to 10 , Figure 7 This is the axial chromatic aberration curve when the lens is focused at infinity. Figure 8 This is a schematic diagram of field curvature and distortion when the lens is focused at infinity. Fig. 9 It is the axial chromatic aberration curve of the lens at the closest focusing distance. Fig.10 This is a schematic diagram of the field curvature and distortion of the lens at the closest focusing distance. Figures 7 to 10 It can be seen that the lens of Example 2 has a good imaging effect.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large aperture medium format wide angle autofocus lens, characterized in that: The lens includes, from the object side to the image side, a first lens group having positive power, a second lens group having negative power, a third lens group having negative power, an aperture stop, a fourth lens group having positive power, and a fifth lens group having negative power; During the focusing process, the second lens group moves along the optical axis from the object side to the image side, and the fourth lens group moves along the optical axis from the image side to the object side; The large aperture medium format wide angle autofocus lens satisfies the following conditional formula: 0.5<F1 / F<2.5; -3.5<F2 / F<-2; 0.5<F4 / F<1.5; 1<F / H<2.5; Among them, F1 is the synthetic focal length of the first lens group, F2 is the synthetic focal length of the second lens group, F4 is the synthetic focal length of the fourth lens group, F is the effective focal length of the lens at infinite working distance, and H is the half image height of the lens.

2. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The lenses of the first lens group, the second lens group, the third lens group, the fourth lens group, and the fifth lens group include at least two aspherical lenses.

3. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: During the focusing process, the first lens group, the third lens group, and the fifth lens group are fixed lens groups.

4. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The first lens group includes, from the object side to the image side, a first lens having negative power, a first optical element having positive power or negative power, and a fourth lens having positive power; Wherein, the first optical element comprises, from the object side to the image side, a second lens having negative optical power and a third lens having positive optical power, and the second lens and the third lens are combined into a cemented lens; or, The first optical element is a lens.

5. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The second lens group includes at least one lens with a refractive index Nd≥1.

8.

6. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The second lens group includes a second optical element having negative optical power; Wherein, the second optical element comprises, from the object side to the image side, a fifth lens having positive power and a sixth lens having negative power, and the fifth lens and the sixth lens are combined into a cemented lens; or, The second optical element is a lens.

7. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The third lens group includes a third optical element having negative optical power; The third optical element includes a seventh lens and an eighth lens in order from the object side to the image side, one of the seventh lens and the eighth lens has a positive optical focal length, and the other has a negative optical focal length, and the seventh lens and the eighth lens are combined into a cemented lens; or The third optical element is a lens.

8. The large aperture medium format wide angle autofocus lens according to claim 7, characterized in that: The seventh lens and the eighth lens satisfy the following conditional formula: |Nd07-Nd08|<0.3; Wherein, Nd07 is the refractive index of the seventh lens, and Nd08 is the refractive index of the eighth lens.

9. The large aperture medium format wide angle autofocus lens according to any one of claims 1 to 8, characterized in that: The fourth lens group includes at least one lens with an Abbe number Vd≥60.

10. The large aperture medium format wide angle autofocus lens according to claim 9, characterized in that: The fourth lens group includes, from the object side to the image side, a ninth lens having positive refractive power and a fourth optical element having positive refractive power; Wherein, the fourth optical element comprises, from the object side to the image side, a tenth lens having positive refractive power and an eleventh lens having negative refractive power, and the tenth lens and the eleventh lens are combined into a cemented lens; or, The fourth optical element is a lens.

11. The large aperture medium format wide angle autofocus lens according to claim 9, characterized in that: The fourth lens group includes, from the object side to the image side, a fifth optical element having positive refractive power and an eleventh lens having positive refractive power; Wherein, the fifth optical element comprises, from the object side to the image side, a ninth lens having negative optical power and a tenth lens having positive optical power, and the ninth lens and the tenth lens are combined into a cemented lens; or, The fifth optical element is a lens.

12. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The fifth lens group includes at least one lens with a refractive index Nd≥1.

8.

13. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The fifth lens group includes, from the object side to the image side, a twelfth lens with positive refractive power, a thirteenth lens with negative refractive power, a fourteenth lens with negative refractive power, and a fifteenth lens with positive refractive power.

14. The large aperture medium format wide angle autofocus lens according to claim 1, characterized in that: The fifth lens group includes, from the object side to the image side, a twelfth lens having positive refractive power, a sixth optical element having negative refractive power, and a fifteenth lens having negative refractive power; Wherein, the sixth optical element comprises, from the object side to the image side, a thirteenth lens having positive refractive power and a fourteenth lens having negative refractive power, and the thirteenth lens and the fourteenth lens are combined into a cemented lens; or, The sixth optical element is a lens.

15. An image pickup device, characterized in that: The invention comprises an image sensor and a large aperture medium format wide angle autofocus lens according to any one of claims 1 to 14, wherein the image sensor is configured to receive an optical image formed by the large aperture medium format wide angle autofocus lens.

Images