A full-frame zoom macro lens

Abstract

The utility model discloses a kind of full-frame zooming micro-lens, including lens group in order from object side to image side along optical axis, lens group at least includes one front group and one rear group, rear group contains at least one super low dispersion lens;The numerical aperture NA of zooming micro-lens satisfies: NA is greater than or equal to 0.13, and the back focal length of zooming micro-lens is changed by moving whole lens group, to be able to have at least two different magnification. Such design makes that lens has high-power micro-lens ability, realizes large aperture design simultaneously, significantly improves the light amount of lens, to reduce the dependence on external strong fill light equipment. Meanwhile, by introducing super low dispersion lens in rear group, so that lens can effectively correct especially easily deteriorated axial chromatic aberration and magnification chromatic aberration under high magnification in the process of realizing 2 times or even higher magnification continuous zooming, so that high resolution, low dispersion excellent optical performance can be obtained in full zoom range.

Description

Technical Field

[0001] This utility model relates to the field of lens technology, and in particular to a full-frame zoom macro lens. Background Technology

[0002] In the existing technology, high-magnification zoom macro lenses adapted to full-frame image sensors (e.g., lenses capable of 2x to 5x or higher magnification) face a long-standing technical challenge. To achieve high magnification, lenses typically need a long back focal length (or achieve zoom through complex lens movements) and a large number of lens elements to correct the resulting sharp increase in various aberrations, especially chromatic aberration and field curvature. This design often results in a lengthy and complex lens optical system.

[0003] To ensure image resolution at high magnification, it's often necessary to sacrifice the lens's light-gathering capacity, meaning a smaller numerical aperture (NA) is used. This directly translates to a smaller maximum aperture (F-number). A smaller NA means a severely insufficient total amount of light entering the lens, forcing photographers to rely on high-powered external artificial light sources for supplemental lighting, often accompanied by extremely slow shutter speeds. This significantly limits shooting flexibility and scene adaptability, making it particularly difficult in natural light, low-light environments, or when shooting live or dynamic micro-subjects.

[0004] Therefore, current technology lacks a macro lens that can achieve high magnification while maintaining a large aperture on a full-frame platform. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a full-frame zoom macro lens.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This utility model provides a full-frame zoom macro lens, which includes lens groups sequentially from the object side to the image side along the optical axis. The lens groups include at least a front group and a rear group, and the rear group contains at least one ultra-low dispersion lens. The numerical aperture NA of the zoom macro lens satisfies: NA≥0.13, and by moving the entire lens group to change the back focal length of the zoom macro lens, it is possible to have at least two different magnifications.

[0007] Furthermore, both the front and rear groups have positive refractive power, and the focal length f1 of the front group and the focal length F of the zoom macro lens satisfy: 1.55≤f1 / F≤1.65.

[0008] Furthermore, the focal length f2 of the rear group and the focal length F of the zoom macro lens satisfy: 3.2≤f2 / F≤3.35.

[0009] Furthermore, the rear group includes at least one cemented lens group, which is formed by cementing a positive refractive power lens and a negative refractive power lens together.

[0010] Furthermore, the focal length f3 of the cemented lens group and the focal length F of the zoom macro lens satisfy: -4.45≤f3 / F≤-4.25.

[0011] Furthermore, the lens group comprises ten independent lenses, all of which are glass spherical lenses.

[0012] Furthermore, along the optical axis from the object side to the image side, the ten independent lenses sequentially include: a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power, a fourth lens with negative refractive power, a fifth lens with positive refractive power and being an ultra-low dispersion lens, a sixth lens with positive refractive power, a seventh lens with positive refractive power, an eighth lens with positive refractive power, a ninth lens with negative refractive power, and a tenth lens with negative refractive power and being an ultra-low dispersion lens.

[0013] Furthermore, the second lens and the third lens are cemented together to form a first cemented group, the fourth lens and the fifth lens are cemented together to form a second cemented group, and the eighth lens and the ninth lens are cemented together to form a third cemented group.

[0014] Furthermore, the light transmission aperture D1 of the first lens and the total optical length TTL of the zoom macro lens satisfy the following condition: 0.12≤D1 / TTL≤0.14.

[0015] Furthermore, the distance from the image side of the last lens in the zoom macro lens to the imaging plane is BFL, and it satisfies the following condition with the total optical length TTL of the zoom macro lens: 0.34≤BFL / TTL≤0.390.

[0016] The beneficial effects of this invention compared to existing technologies are as follows: A full-frame zoom macro lens comprises lens groups sequentially along the optical axis from the object side to the image side. Each lens group includes at least a front group and a rear group, with the rear group containing at least one ultra-low dispersion lens. The numerical aperture (NA) of the zoom macro lens satisfies NA ≥ 0.13, and by moving the entire lens group to change the back focal length, it can achieve at least two different magnifications. This design allows the lens to achieve a large aperture while possessing high-magnification macro capabilities, significantly increasing the amount of light entering the lens and reducing reliance on external strong illumination devices. Simultaneously, by introducing an ultra-low dispersion lens in the rear group, the lens can effectively correct axial chromatic aberration and magnification chromatic aberration, which are prone to deterioration, especially at high magnification, during continuous zoom operations at 2x or even higher magnifications. This results in excellent optical performance with high resolution and low dispersion across the entire zoom range.

[0017] The above description is only an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model, it can be implemented according to the contents of the specification. In order to make the above and other objectives, features and advantages of this utility model more obvious and easy to understand, the following are preferred embodiments, which are described in detail below. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of the structure of a full-frame zoom macro lens provided for a specific embodiment of this utility model; Figure 2 A 2x MTF plot is provided for a specific embodiment of this utility model; Figure 3 A 2x vertical axis color difference diagram provided for a specific embodiment of this utility model; Figure 4 A 2x distortion image provided for a specific embodiment of this utility model; Figure 5 A 5x MTF plot is provided for a specific embodiment of this utility model; Figure 6 A 5x vertical axis color difference diagram is provided for a specific embodiment of this utility model; Figure 7 A 5x distortion image provided for a specific embodiment of this utility model.

[0020] Figure Labels 1. Front group; 11. First lens; 12. Second lens; 13. Third lens; 2. Rear group; 21. Fourth lens; 22. Fifth lens; 23. Sixth lens; 24. Seventh lens; 25. Eighth lens; 26. Ninth lens; 27. Tenth lens; 100. Image plane. Detailed Implementation

[0021] The technical solution of this utility model will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0025] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0026] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0027] like Figures 1 to 7 As shown, this embodiment of the present invention provides a full-frame zoom macro lens, which includes lens groups sequentially from the object side to the image side along the optical axis. The lens groups include at least a front group 1 and a rear group 2, and the rear group 2 includes at least one ultra-low dispersion lens. The numerical aperture NA of the zoom macro lens satisfies: NA≥0.13, and by moving the entire lens group to change the back focal length of the zoom macro lens, it is possible to have at least two different magnifications.

[0028] exist Figure 1In the illustrated embodiment, the lens group comprises ten independent lenses, all of which are glass spherical lenses. Along the optical axis from the object side to the image side, the ten independent lenses sequentially include: a first lens 11 with positive refractive power, a second lens 12 with positive refractive power, a third lens 13 with negative refractive power, a fourth lens 21 with negative refractive power, a fifth lens 22 with positive refractive power and being an ultra-low dispersion lens, a sixth lens 23 with positive refractive power, a seventh lens 24 with positive refractive power, an eighth lens 25 with positive refractive power, a ninth lens 26 with negative refractive power, and a tenth lens 27 with negative refractive power and being an ultra-low dispersion lens. The front group 1 consists of the first lens 11, the second lens 12, and the third lens 13, while the rear group 2 consists of the fourth lens 21 to the tenth lens 27. The rear group 2 includes two ultra-low dispersion lenses, the fifth lens 22 and the tenth lens 27, which can be of model LAK14 or E-FDS1. This zoom macro lens has a numerical aperture (NA) of 0.13±3%, corresponding to a large aperture characteristic, which increases the amount of light entering the lens and effectively solves the problem of relying on external lighting equipment for shooting in low-light environments. The zoom function is achieved by moving the entire lens group. Specifically, a stepper motor built into the lens drives the lens group to translate along the optical axis, changing the back focal length to switch the magnification: when the back focal length is adjusted to 42mm, 2x macro magnification is achieved; when the back focal length is 68.14mm, 3x macro magnification is achieved; when the back focal length is 92.2mm, 4x macro magnification is achieved; and when the back focal length is 117.3mm, 5x macro magnification is achieved, covering users' core needs for 2-5x high-magnification macro photography.

[0029] This design allows the lens to achieve both high-magnification macro capabilities and a large aperture, significantly increasing the amount of light entering the lens and reducing reliance on external strong lighting equipment. Simultaneously, by introducing an ultra-low dispersion lens in rear group 2, the lens can effectively correct axial chromatic aberration and magnification chromatic aberration, which are prone to deterioration, especially at high magnification, during continuous zoom operations of 2x or higher. This results in excellent optical performance with high resolution and low dispersion across the entire zoom range.

[0030] In some embodiments, only one ultra-low dispersion lens may be configured in the rear group 2, preferably at the position of the fifth lens 22. In this case, the refractive index parameters of other lenses need to be finely adjusted to compensate for the chromatic aberration correction capability of a single ultra-low dispersion lens. It should be noted that the zoom method can be changed to move only the rear group 2 lens while the front group 1 is fixed, and the back focal length can be changed by adjusting the distance of the rear group 2 relative to the front group 1.

[0031] In some embodiments, both the front group 1 and the rear group 2 have positive refractive power, and the focal length f1 of the front group 1 and the focal length F of the zoom macro lens satisfy: 1.55≤f1 / F≤1.65.

[0032] In this embodiment, the glass material refractive indices Nd of the first lens 11, second lens 12, third lens 13, fourth lens 21, fifth lens 22, sixth lens 23, seventh lens 24, eighth lens 25, ninth lens 26 and tenth lens 27 satisfy the following: 1.80≤Nd1≤1.81, 1.59≤Nd2≤1.60, 1.80≤Nd3≤1.82, 1.80≤Nd4≤1.82, 1.49≤Nd5≤1.51, 1.56≤Nd6≤1.58, 1.72≤Nd7≤1.74, 1.73≤Nd8≤1.75, 1.77≤Nd9≤1.79, and 1.49≤Nd10≤1.51.

[0033] The Abbe numbers Vd of the glass materials of the first lens 11, the second lens 12, the third lens 13, the fourth lens 21, the fifth lens 22, the sixth lens 23, the seventh lens 24, the eighth lens 25, the ninth lens 26, and the tenth lens 27 satisfy the following conditions: 35≤Vd1≤35.1, 68.2≤Vd2≤68.4, 46.5≤Vd3≤46.7, 33.2≤Vd4≤33.4, 81.5≤Vd5≤81.7, 56≤Vd6≤56.1, 28.2≤Vd7≤28.4, 49.1≤Vd8≤49.3, 47.4≤Vd9≤47.6, and 81.5≤Vd10≤81.7.

[0034] For example, if the total focal length F of the lens is set to 100mm, and the focal length f1 of the front group 1 is 160mm, then f1 / F = 1.6 can be calculated. The specific parameters of the three lenses in the front group 1 are as follows: the first lens 11 is a biconvex positive diopter glass lens with a refractive index Nd1 = 1.805 and an Abbe number Vd1 = 35.05; the second lens 12 is a biconvex positive diopter glass lens with a refractive index Nd2 = 1.595 and an Abbe number Vd2 = 68.3; and the third lens 13 is a biconcave negative diopter glass lens with a refractive index Nd3 = 1.81 and an Abbe number Vd3 = 46.6. The three lenses are sequentially attached along the optical axis and fixed with optical adhesive to form an integrated front group 1, ensuring the stability of the group's focal length.

[0035] The combination of the front group 1 and the rear group 2 with positive refractive power makes the optical power distribution of the lens optical system more uniform, avoids the aberration accumulation caused by excessive optical power of a single group, and provides a guarantee for high-resolution imaging. The focal length ratio of 1.55-1.65 allows for an optimal balance between the light transmission efficiency of the front group 1 and the imaging magnification efficiency of the rear group 2, achieving a large aperture while controlling the size of the front group 1 and avoiding an overly bulky overall lens. In some embodiments, the focal length f2 of the rear group 2 and the focal length F of the zoom macro lens satisfy: 3.2≤f2 / F≤3.35.

[0036] For example, continuing with the above embodiment, the total focal length of the lens is F=100mm, and the focal length f2 of the rear group 2 is 328mm, so f2 / F=3.28. The rear group 2 consists of the fourth lens 21 to the tenth lens 27, where the fourth lens 21 is a biconcave negative diopter glass lens (Nd4=1.81, Vd4=33.3), the fifth lens 22 is a biconvex positive diopter extra-low dispersion glass lens (Nd5=1.50, Vd5=81.6), the sixth lens 23 is a meniscus positive diopter glass lens (one convex and one concave, Nd6=1.57, Vd6=56.05), and the seventh lens 24 is a meniscus positive diopter glass lens (one concave and one convex, Nd7=1.73, Vd7=28). 3) The eighth lens 25 is a biconvex positive diopter glass lens (Nd8=1.74, Vd8=49.2), the ninth lens 26 is a biconcave negative diopter glass lens (Nd9=1.78, Vd9=47.5), and the tenth lens 27 is a meniscus negative diopter ultra-low dispersion glass lens (one concave and one convex, Nd10=1.50, Vd10=81.6). The seven lenses are arranged along the optical axis in the above order. The aperture stop is set between the third lens 13 and the fourth lens 21, and the optical distance from the third lens 13 is 12mm.

[0037] The rear group 2 focal length ratio design of 3.2-3.35 complements the front group 1 focal length ratio, making the focal length distribution of the entire optical system more reasonable and effectively compressing the total optical length TTL of the lens. At F=100mm, the TTL can be controlled within 180mm. The refractive power combination of multiple lenses in the rear group 2 can effectively correct spherical aberration and coma under high magnification, and further improve image clarity when combined with ultra-low dispersion lenses; In some embodiments, the rear group 2 includes at least one cemented lens assembly, which is formed by cementing a positive refractive power lens and a negative refractive power lens together.

[0038] For example, the first cemented assembly is formed by bonding the second lens 12 (positive refractive power, biconvex) and the third lens 13 (negative refractive power, biconcave) with optical resin adhesive; the second cemented assembly is formed by bonding the fourth lens 21 (negative refractive power, biconcave) and the fifth lens 22 (positive refractive power, biconvex, ultra-low dispersion); and the third cemented assembly is formed by bonding the eighth lens 25 (positive refractive power, biconvex) and the ninth lens 26 (negative refractive power, biconcave). During the bonding process, ultraviolet-cured optical adhesive is used to ensure the optical accuracy of the lens assembly.

[0039] Cemented lenses, formed by bonding negative diopter lenses, can utilize the difference in refractive index and Abbe number between the two lens materials to partially cancel out chromatic aberration and spherical aberration. Compared to a single-lens design, this reduces transverse chromatic aberration, ensuring color reproduction under high magnification. At the same time, the integrated design of the cemented lens reduces the air gap between the lenses, reducing stray light generation and improving the mechanical stability of the lens, thus avoiding imaging deviations caused by lens displacement during long-term use. In some embodiments, the focal length f3 of the cemented lens group and the focal length F of the zoom macro lens satisfy: -4.45≤f3 / F≤-4.25.

[0040] For example, continuing with the above embodiment with F=100mm, the focal length f3 of the second cemented group is -435mm, and the calculated f3 / F = -4.35. The focal length ratio design of -4.45 to -4.25 gives the second cemented group a strong negative optical power, which can effectively counteract the overcorrected aberrations produced by other lenses in the rear group 2, especially having a significant corrective effect on field curvature and distortion under high magnification.

[0041] In some embodiments, the second lens 12 and the third lens 13 are cemented together to form a first cemented group, the fourth lens 21 and the fifth lens 22 are cemented together to form a second cemented group, and the eighth lens 25 and the ninth lens 26 are cemented together to form a third cemented group.

[0042] The three-part paired cemented design makes the lens group structure more compact, which can shorten the total optical length (TTL) of the lens compared to the non-cemented design. In some embodiments, the light-transmitting aperture D1 of the first lens 11 and the total optical length TTL of the zoom macro lens satisfy the following condition: 0.12≤D1 / TTL≤0.14.

[0043] In specific implementation, the light-transmitting aperture D1 (effective light-transmitting diameter) of the first lens 11 is set to 24mm, and the total optical length TTL (distance from the object side of the first lens 11 to the imaging surface 100) of the lens is set to 180mm. The calculation shows that D1 / TTL = 24 / 180 ≈ 0.133.

[0044] The design of a light-transmitting aperture to total length ratio of 0.12-0.14 ensures that the light transmission efficiency of the first lens 11 meets the requirements of a large aperture, while avoiding the increase in lens weight and cost caused by an excessively large aperture of the first lens 11.

[0045] In some embodiments, the distance from the image side of the last lens in the zoom macro lens to the imaging plane 100 is BFL, and it satisfies the following condition with respect to the total optical length TTL of the zoom macro lens: 0.34≤BFL / TTL≤0.390.

[0046] The BFL / TTL ratio design of 0.34-0.39 provides ample space for the installation of the imaging plane 100, facilitating the integration of additional components such as filters and image stabilization mechanisms, while avoiding the increase of stray light caused by excessively long BFLs. During zooming, the adjustment range of BFL is strictly limited to this ratio to ensure that changes in the lens's back focal length do not cause the imaging plane to shift beyond the sensor's range, thus guaranteeing imaging integrity at multiple magnifications.

[0047] from Figures 2 to 7 It is known that this macro lens has the characteristics of high resolution, low chromatic aberration, and low distortion in the high magnification range of 2x to 5x, successfully solving the key defects of existing high-magnification macro lenses and meeting the needs of professional microscopic imaging.

[0048] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A full-frame zoom macro lens, characterized in that, The optical axis includes lens groups from the object side to the image side, and the lens groups include at least a front group and a rear group, the rear group containing at least one ultra-low dispersion lens; The numerical aperture NA of the zoom macro lens satisfies: NA≥0.13, and by moving the entire lens group to change the back focal length of the zoom macro lens, it is possible to have at least two different magnifications.

2. The full-frame zoom macro lens according to claim 1, characterized in that, Both the front and rear groups have positive refractive power, and the focal length f1 of the front group and the focal length F of the zoom macro lens satisfy: 1.55≤f1 / F≤1.

65.

3. A full-frame zoom macro lens according to claim 2, characterized in that, The focal length f2 of the rear group and the focal length F of the zoom macro lens satisfy the condition: 3.2≤f2 / F≤3.

35.

4. A full-frame zoom macro lens according to any one of claims 1-3, characterized in that, The rear group includes at least one cemented lens group, which is formed by cementing together a positive refractive power lens and a negative refractive power lens.

5. A full-frame zoom macro lens according to claim 4, characterized in that, The focal length f3 of the cemented lens group and the focal length F of the zoom macro lens satisfy the condition: -4.45≤f3 / F≤-4.

25.

6. A full-frame zoom macro lens according to claim 1, characterized in that, The lens group comprises ten independent lenses, all of which are glass spherical lenses.

7. A full-frame zoom macro lens according to claim 6, characterized in that, Along the optical axis from the object side to the image side, the ten independent lenses sequentially include: a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power, a fourth lens with negative refractive power, a fifth lens with positive refractive power and being an ultra-low dispersion lens, a sixth lens with positive refractive power, a seventh lens with positive refractive power, an eighth lens with positive refractive power, a ninth lens with negative refractive power, and a tenth lens with negative refractive power and being an ultra-low dispersion lens.

8. A full-frame zoom macro lens according to claim 7, characterized in that, The second lens and the third lens are cemented together to form a first cemented group, the fourth lens and the fifth lens are cemented together to form a second cemented group, and the eighth lens and the ninth lens are cemented together to form a third cemented group.

9. A full-frame zoom macro lens according to claim 7, characterized in that, The light-transmitting aperture D1 of the first lens and the total optical length TTL of the zoom macro lens satisfy the following condition: 0.12≤D1 / TTL≤0.

14.

10. A full-frame zoom macro lens according to claim 1 or 7, characterized in that, The distance from the image side of the last lens in the zoom macro lens to the imaging plane is BFL, and it satisfies the following condition with the total optical length TTL of the zoom macro lens: 0.34≤BFL / TTL≤0.390.

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