Lens assembly and optical system

Abstract

This application provides a lens assembly and an optical system, relating to the field of optical technology. The lens assembly includes a first lens group and a second lens group. The first lens group includes a first lens to a sixth lens; the second lens group includes a seventh lens to a twelfth lens. The lens assembly satisfies: 4.10 ≤ f2 / CT2 ≤ 7.66; 8.00 < FG2 / ΔL < 10.15; f2 is the effective focal length of the second lens, CT2 is the center thickness of the second lens, FG2 is the combined focal length of the second lens group, and ΔL is the distance the second lens group moves along the optical axis when the lens assembly changes from an infinite object distance to a 1000mm object distance. This lens assembly effectively extends telephoto shooting capabilities while ensuring image quality.

Description

Technical Field

[0001] This application relates to the field of optics, and more specifically, to a lens assembly and an optical system. Background Technology

[0002] As the telephoto capabilities of electronic devices (such as mobile phones and tablets) continue to improve, the focal length extension range of built-in lens systems remains limited by their compact packaging space and heat dissipation layout. To meet the needs of ultra-long-distance shooting, external extension lenses have become a common solution for expanding magnification.

[0003] Traditional external extension lenses often employ simple single or double lens groups. Their optical design lacks specific matching to the native optical path structure of electronic devices. After installation, they often introduce significant spherical aberration, coma, and chromatic aberration, resulting in reduced edge resolution, lower overall contrast, and an inability to accurately reproduce the details of the subject. Furthermore, most external extension lenses lack zoom adjustment capabilities, limiting their versatility at different object distances. Summary of the Invention

[0004] One aspect of this application provides a lens assembly, which includes a first lens group and a second lens group sequentially from the object side to the image side along the optical axis. The first lens group has positive optical power and includes: a first lens with positive optical power, wherein the object side of the first lens is convex; a second lens with positive optical power, wherein the object side and the image side of the second lens are both convex; a third lens with negative optical power, wherein the object side and the image side of the third lens are both concave; a fourth lens with positive optical power, wherein the object side of the fourth lens is convex; a fifth lens with positive optical power, wherein the object side of the fifth lens is convex and the image side of the fifth lens is concave; and a sixth lens with negative optical power, wherein the image side of the sixth lens is concave. The second lens group has positive optical power and includes: a seventh lens with positive optical power, wherein the image side of the seventh lens is convex; and a third lens with negative optical power. The system comprises eight lenses, wherein the object-side surface of the eighth lens is concave and the image-side surface of the eighth lens is concave; a ninth lens with positive optical power, wherein the image-side surface of the ninth lens is convex; a tenth lens with negative optical power, wherein the object-side surface of the tenth lens is concave and the image-side surface of the tenth lens is concave; an eleventh lens with positive optical power, wherein the image-side surface of the eleventh lens is convex; and a twelfth lens with positive optical power, wherein the image-side surface of the twelfth lens is convex; wherein the second lens and the third lens are cemented together, and the second lens group can move along the optical axis to achieve zoom; the lens group satisfies: 4.10≤f2 / CT2≤7.66, 8.00<FG2 / ΔL<10.15, where f2 is the effective focal length of the second lens, CT2 is the center thickness of the second lens, FG2 is the combined focal length of the second lens group, and ΔL is the distance the second lens group moves along the optical axis when the lens group changes from an infinite object distance to a 1000mm object distance.

[0005] According to an embodiment of this application, the lens group satisfies: -1.70 < f1 / F23 < -0.75, where f1 is the effective focal length of the first lens and F23 is the combined focal length of the second lens and the third lens.

[0006] According to an embodiment of this application, the lens group satisfies: 0.95 < LG1 / FG1 ≤ 1.45, where LG1 is the axial distance from the object side of the first lens to the image side of the sixth lens, and FG1 is the combined focal length of the first lens group.

[0007] According to an embodiment of this application, the lens group satisfies: 5.65 < F1234 / T45 < 6.35, where F1234 is the combined focal length of the first lens, the second lens, the third lens, and the fourth lens, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

[0008] According to an embodiment of this application, the lens group satisfies: 1.70 < R6 / (CT2+CT3) ≤ 2.90, where R6 is the radius of curvature of the image side of the third lens, and CT3 is the center thickness of the third lens.

[0009] According to an embodiment of this application, the lens group satisfies: 7.30 < F789 / ΔL < 9.75, where F789 is the combined focal length of the seventh lens, the eighth lens, and the ninth lens.

[0010] According to an embodiment of this application, the lens group satisfies: 1.40 < F101112 / ∑CTG2 < 2.20, where F101112 is the combined focal length of the tenth lens, the eleventh lens and the twelfth lens, and ∑CTG2 is the sum of the center thicknesses of all lenses from the seventh lens to the twelfth lens.

[0011] According to an embodiment of this application, the lens group satisfies: 0.80 < LG2 / f12 ≤ 1.15, where LG2 is the axial distance from the object side of the seventh lens to the image side of the twelfth lens, and f12 is the effective focal length of the twelfth lens.

[0012] According to an embodiment of this application, the lens group satisfies: -1.35 < R22 / f11 < -0.70, where R22 is the radius of curvature of the image side surface of the eleventh lens, and f11 is the effective focal length of the eleventh lens.

[0013] According to an embodiment of this application, the lens group satisfies: -3.60 < (f5 × N5) / (f6 × N6) < -0.55, where f5 is the effective focal length of the fifth lens, N5 is the refractive index of the fifth lens, f6 is the effective focal length of the sixth lens, and N6 is the refractive index of the sixth lens.

[0014] According to an embodiment of this application, the lens group satisfies: -10.22≤F1011 / (CT10+CT11)≤-3.86, where F1011 is the combined focal length of the tenth lens and the eleventh lens, CT10 is the center thickness of the tenth lens, and CT11 is the center thickness of the eleventh lens.

[0015] According to an embodiment of this application, the lens group satisfies: 1.10 < f4 / ∑CTG1 < 2.60, where f4 is the effective focal length of the fourth lens, and ∑CTG1 is the sum of the center thicknesses of all lenses from the first lens to the sixth lens.

[0016] According to an embodiment of this application, the lens group satisfies: -7.75≤R24 / CT12<-5.10, where R24 is the radius of curvature of the image-side surface of the twelfth lens, and CT12 is the center thickness of the twelfth lens.

[0017] Another aspect of this application provides an optical system comprising a lens group as provided in any embodiment of this application, an imaging lens located on the image side of the twelfth lens, and an imaging surface. The outgoing light beam from the lens group enters the imaging lens to form an image on the imaging surface using the imaging lens. The optical system satisfies: 16.25 ≤ TDq / Δf ≤ 19.98, where TDq is the axial distance from the object side of the first lens to the image side of the twelfth lens when the lens group is in the infinite object distance state, and Δf is the change in effective focal length of the optical system when the object distance changes from the infinite object distance state to the 1000mm object distance state.

[0018] According to an embodiment of this application, the optical system satisfies: 1.95≤Δf / ΔL<3.00, where Δf is the change in effective focal length of the optical system when it changes from the infinite object distance state to the 1000mm object distance state.

[0019] According to the technical solution of this application embodiment, the lens group is reasonably configured. Through the synergistic constraints of the two conditional expressions 4.10≤f2 / CT2≤7.66 and 8.00<FG2 / ΔL<10.15, a comprehensive balance between high-magnification telephoto extension and clear imaging at different object distances is achieved. This avoids higher-order aberrations caused by excessive curvature of the surface, ensures that the lens has sufficient rigidity to resist molding shrinkage and thermal deformation, and ensures that the combined focal length of the second lens group is matched with the zoom movement stroke to ensure that each unit displacement contributes sufficient focal length increment to achieve high-magnification switching. This avoids excessively long strokes leading to drive lag or excessively short strokes leading to insufficient focusing resolution, which is beneficial to improving zoom response speed and focusing accuracy. Attached Figure Description

[0020] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:

[0021] Figure 1 This application provides a schematic diagram of the overall architecture of an optical system. Figure 2 This paper shows a schematic diagram of the lens assembly in the first state according to Embodiment 1 provided in this application; Figure 3 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 1 in the first state is shown. Figure 4 This paper shows a schematic diagram of the lens assembly in the second state according to Embodiment 1 provided in this application; Figure 5 A schematic diagram showing the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 1 in the second state is shown. Figure 6 This paper shows a schematic diagram of the lens assembly in the first state according to Embodiment 2 provided in this application; Figure 7 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 2 in the first state is shown. Figure 8 This paper shows a schematic diagram of the lens assembly in the second state according to Embodiment 2 provided in this application; Figure 9 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 2 in the second state is shown. Figure 10 This paper shows a schematic diagram of the lens assembly in the first state according to Embodiment 3 provided in this application; Figure 11 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 3 in the first state is shown. Figure 12 This paper shows a schematic diagram of the lens assembly in the second state according to Embodiment 3 of this application; Figure 13 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 3 in the second state is shown. Figure 14 This paper shows a schematic diagram of the lens assembly in the first state according to Embodiment 4 of this application; Figure 15 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 4 in the first state is shown. Figure 16 This paper shows a schematic diagram of the lens assembly in the second state according to Embodiment 4 of this application; Figure 17 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 4 in the second state is shown. Figure 18 This paper shows a schematic diagram of the lens assembly in the first state according to Embodiment 5 of this application; Figure 19A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 5 in the first state is shown. Figure 20 This application provides a schematic diagram of the lens assembly in its second state according to Embodiment 5; and Figure 21 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 5 in the second state is shown. Detailed Implementation

[0022] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0023] It should be noted that in this specification, the terms "first," "second," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens, and the second lens may also be referred to as the first lens.

[0024] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0025] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region.

[0026] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0027] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] The features, principles and other aspects of this application are described in detail below.

[0030] This application proposes a lens group consisting of two groups of six lenses each (referred to as the "first lens group" and the "second lens group" respectively). By controlling the movement of the second lens group along the optical axis, zoom from infinity to close-up distance can be achieved, effectively extending the telephoto shooting capability while maintaining the original imaging quality of the electronic device.

[0031] This application provides a lens assembly, which includes a first lens group and a second lens group in sequence from the object side to the image side along the optical axis.

[0032] The first lens group has positive optical power and includes: a first lens with positive optical power, wherein the object-side surface of the first lens is convex; a second lens with positive optical power, wherein both the object-side and image-side surfaces of the second lens are convex; a third lens with negative optical power, wherein both the object-side and image-side surfaces of the third lens are concave; a fourth lens with positive optical power, wherein the object-side surface of the fourth lens is convex; a fifth lens with positive optical power, wherein both the object-side and image-side surfaces of the fifth lens are concave; and a sixth lens with negative optical power, wherein the image-side surface of the sixth lens is concave.

[0033] The second lens group has positive optical power and includes: a seventh lens with positive optical power, the image-side surface of the seventh lens being convex; an eighth lens with negative optical power, the object-side surface of the eighth lens being concave, and the image-side surface of the eighth lens being concave; a ninth lens with positive optical power, the image-side surface of the ninth lens being convex; a tenth lens with negative optical power, the object-side surface of the tenth lens being concave, and the image-side surface of the tenth lens being concave; an eleventh lens with positive optical power, the image-side surface of the eleventh lens being convex; and a twelfth lens with positive optical power, the image-side surface of the twelfth lens being convex.

[0034] The second and third lenses are cemented together, and the second lens group can move along the optical axis to achieve zoom. The lens group satisfies: 4.10≤f2 / CT2≤7.66, 8.00<FG2 / ΔL<10.15, where f2 is the effective focal length of the second lens, CT2 is the center thickness of the second lens, FG2 is the combined focal length of the second lens group, and ΔL is the distance the second lens group moves along the optical axis when the lens group changes from an infinite object distance state to a 1000mm object distance state.

[0035] The lens group provided in this application achieves a comprehensive balance between high-magnification telephoto extension and clear imaging at different object distances through the synergistic constraints of two conditional expressions: 4.10≤f2 / CT2≤7.66 and 8.00<FG2 / ΔL<10.15. This avoids higher-order aberrations caused by excessive curvature of the surface, ensures that the lens has sufficient rigidity to resist molding shrinkage and thermal deformation, and the combined focal length of the second lens group matches the zoom movement stroke, ensuring that each unit displacement contributes sufficient focal length increment to achieve high-magnification switching. This avoids excessively long strokes leading to drive lag or excessively short strokes leading to insufficient focusing resolution, which is beneficial to improving zoom response speed and focusing accuracy.

[0036] In an exemplary embodiment, the lens group satisfies: -1.70 < f1 / F23 < -0.75, where f1 is the effective focal length of the first lens and F23 is the combined focal length of the second and third lenses. This embodiment reasonably controls the range of the above conditional expression, so that the positive optical power of the first lens and the combined negative optical power of the cemented group of the second and third lenses mutually restrict each other, ensuring that the two form a reasonable complementarity in light refraction. At the same time, it helps to reduce the overall aberration residual amount of the system and avoid the increase in local sensitivity caused by the imbalance of optical power distribution.

[0037] In an exemplary embodiment, the lens group satisfies: 0.95 < LG1 / FG1 ≤ 1.45, where LG1 is the axial distance from the object-side surface of the first lens to the image-side surface of the sixth lens, and FG1 is the combined focal length of the first lens group. This embodiment reasonably controls the range of the above conditional expression, making the axial length of the first lens group close to its combined focal length, ensuring a reasonable distribution of optical power among the lenses within the group, avoiding the introduction of additional aberrations due to the lens group being too long or too short, and at the same time, it helps to compress the radial dimensions of the lens group, reserving ample space for the second lens group to move along the optical axis, and reducing image plane fluctuations during zooming.

[0038] In an exemplary embodiment, the lens group satisfies: 5.65 < F1234 / T45 < 6.35, where F1234 is the combined focal length of the first, second, third, and fourth lenses, and T45 is the air gap between the fourth and fifth lenses on the optical axis. This embodiment reasonably controls the range of the above conditional expression, ensuring that the combined focal length of the first four lenses is coordinated with the air gap between the fourth and fifth lenses. This ensures that the light rays converged by the front positive optical power group are incident on the subsequent lenses at an appropriate angle, which helps control the divergence of the light beam in this interval region, avoids excessive light deflection that introduces higher-order aberrations, and provides good incident conditions for aberration correction of the subsequent group.

[0039] In an exemplary embodiment, the lens group satisfies: 1.70 < R6 / (CT2+CT3) ≤ 2.90, where R6 is the radius of curvature of the image-side surface of the third lens, and CT3 is the center thickness of the third lens. This embodiment reasonably controls the range of the above conditional expression, so that the radius of curvature of the image-side surface of the third lens matches the sum of the thicknesses of the second and third lenses, ensuring a smooth transition of the overall surface shape of the cemented assembly, effectively suppressing large-angle refraction of light at the interface, which helps to reduce stress concentration on the cemented surface and improve the stability and yield of the cementing process.

[0040] In an exemplary embodiment, the lens group satisfies: 7.30 < F789 / ΔL < 9.75, where F789 is the combined focal length of the seventh, eighth, and ninth lenses. This embodiment reasonably controls the range of the above conditional expression, ensuring a good match between the combined focal length of the seventh, eighth, and ninth lenses and the zoom movement distance of the second lens group. This ensures that the seventh to ninth lenses provide a stable positive optical power contribution during the movement, which is beneficial for controlling the image plane displacement throughout the zoom range, avoiding excessively steep or gradual focal length changes per unit travel, and improving focusing smoothness and accuracy.

[0041] In an exemplary embodiment, the lens group satisfies: 1.40 < F101112 / ∑CTG2 < 2.20, where F101112 is the combined focal length of the tenth, eleventh, and twelfth lenses, and ∑CTG2 is the sum of the center thicknesses of all lenses from the seventh to the twelfth lens. This embodiment reasonably controls the range of the above conditional expression, ensuring that the combined focal length of the tenth, eleventh, and twelfth lenses is in a reasonable ratio to the total thickness of the second lens group. This ensures that the last three lenses have sufficient optical power to gather light and compensate for residual aberrations in the preceding group, while also balancing the compactness of the lens group with aberration correction capabilities, and avoiding high-level astigmatism caused by excessive optical power.

[0042] In an exemplary embodiment, the lens group satisfies: 0.80 < LG2 / f12 ≤ 1.15, where LG2 is the axial distance from the object-side surface of the seventh lens to the image-side surface of the twelfth lens, and f12 is the effective focal length of the twelfth lens. This embodiment reasonably controls the range of the above-mentioned conditional expression, ensuring that the twelfth lens occupies an appropriate weight within the second lens group to exert its converging effect. This helps to constrain the light refraction distribution of each lens within the second lens group, avoiding redundancy due to excessive total length or additional aberrations introduced by excessively short focal length, and providing good angular conditions for the outgoing light rays.

[0043] In an exemplary embodiment, the lens group satisfies: -1.35 < R22 / f11 < -0.70, where R22 is the radius of curvature of the image-side surface of the eleventh lens, and f11 is the effective focal length of the eleventh lens. This embodiment reasonably controls the range of the above-mentioned conditional expression, ensuring that the eleventh lens provides positive optical power while avoiding excessive curvature of the image-side surface. This is beneficial for controlling the light emission angle, reducing the contribution of the image-side curvature to advanced astigmatism, and reducing the difficulty of aspherical surface processing.

[0044] In an exemplary embodiment, the lens group satisfies: -3.60 < (f5 × N5) / (f6 × N6) < -0.55, where f5 is the effective focal length of the fifth lens, N5 is the refractive index of the fifth lens, f6 is the effective focal length of the sixth lens, and N6 is the refractive index of the sixth lens. This embodiment reasonably controls the range of the above conditional expression, so that the fifth and sixth lenses form an inverse complementary relationship in terms of optical power and material refractive index. This helps to eliminate the residual transverse chromatic aberration and astigmatism of the front lens group, while balancing the optical power distribution of the two lenses, avoiding over-compensation or under-compensation, and ensuring consistent image sharpness across the entire field of view.

[0045] In an exemplary embodiment, the lens group satisfies: -10.22 ≤ F1011 / (CT10+CT11) ≤ -3.86, where F1011 is the combined focal length of the tenth and eleventh lenses, CT10 is the center thickness of the tenth lens, and CT11 is the center thickness of the eleventh lens. This embodiment reasonably controls the range of the above conditional expression, enabling the tenth and eleventh lenses to contribute an appropriate combined negative optical power. Combined with the thickness ratio of the two lenses, it effectively corrects residual axial chromatic aberration and field curvature, providing reliable incident conditions for aberration compensation by subsequent lenses.

[0046] In an exemplary embodiment, the lens group satisfies: 1.10 < f4 / ∑CTG1 < 2.60, where f4 is the effective focal length of the fourth lens, and ∑CTG1 is the sum of the center thicknesses of all lenses from the first to the sixth lens. This embodiment reasonably controls the range of the above conditional expression, ensuring that the fourth lens can effectively receive the converging light from the front and transmit it to the rear lens group at an appropriate angle. This avoids the optical focal length of the fourth lens being too concentrated or dispersed, which helps to reduce the sensitivity distribution of each lens in the first lens group and improves the assembly tolerance.

[0047] In an exemplary embodiment, the lens group satisfies: -7.75 ≤ R24 / CT12 < -5.10, where R24 is the radius of curvature of the image-side surface of the twelfth lens, and CT12 is the center thickness of the twelfth lens. This embodiment reasonably controls the range of the above conditional expression to ensure a smooth surface transition when the twelfth lens converges the outgoing light rays, while also taking into account the matching requirements of the principal ray angle of the image plane and the imaging chip, avoiding molding defects and increased internal stress caused by excessively concave surface or excessively thick lens.

[0048] This application also provides an optical system comprising a lens group as provided in any embodiment of this application, an imaging lens located on the image side of the twelfth lens, and an imaging plane. The beam emitted from the lens group enters the imaging lens to form an image on the imaging plane. The optical system satisfies: 16.25 ≤ TDq / Δf ≤ 19.98, where TDq is the axial distance from the object side of the first lens to the image side of the twelfth lens when the lens group is at infinite object distance, and Δf is the change in effective focal length when the optical system changes from an infinite object distance to a 1000mm object distance. This embodiment reasonably controls the range of the above-mentioned conditional expression to ensure that the axial dimension matches the magnification switching range, which is beneficial to ensuring the consistency of the image plane position during zooming, avoiding image quality fluctuations caused by total length redundancy or excessive focal length increment, and reserving sufficient adaptation space for the imaging lens.

[0049] In an exemplary embodiment, the optical system satisfies: 1.95 ≤ Δf / ΔL < 3.00, where Δf is the change in effective focal length when the optical system changes from an infinite object distance to a 1000mm object distance. This embodiment reasonably controls the range of the above-mentioned conditional expression, so that the change in system focal length and the movement stroke of the second lens group form a reasonable gain correspondence. This ensures that the magnification change caused by each unit displacement is smooth and controllable, which is beneficial for balancing focusing sensitivity and stroke utilization efficiency. It avoids drastic changes in image quality caused by slight displacement due to excessive gain, or sacrificing response speed due to large movement required by excessively low gain.

[0050] In some embodiments of this application, the imaging lens can be the native lens of an electronic device (e.g., a mobile phone, a tablet computer), and the lens group can refer to an external or additional imaging system, such as an external extension lens. The imaging lens is a core optical component located behind the lens group and adjacent to the image sensor along the optical axis. It is used to finally converge the light rays corrected and optimized by the front lens group to form a clear real image on the imaging surface. For example, the native lens of a mobile phone can be used to converge the light rays from an external extension lens, ultimately forming an image on the imaging surface. The imaging surface is, for example, the photosensitive surface of an image sensor.

[0051] Figure 1 A schematic diagram of the overall architecture of an optical system provided in this application is shown.

[0052] like Figure 1 As shown, the optical system includes a lens group 10 and an imaging lens 20. The lens group 10 and the imaging lens 20 are arranged sequentially from the object side to the image side along the optical axis. The imaging lens 20 is adjacent to the imaging surface IMG. The imaging surface IMG is, for example, the photosensitive surface of an image sensor.

[0053] The lens group 10 includes a first lens group G1 and a second lens group G2. The first lens group G1 has positive optical power, and the second lens group G2 has positive optical power.

[0054] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens E1 has positive optical power, and its object-side surface is convex. The second lens E2 has positive optical power, and both its object-side and image-side surfaces are convex. The third lens E3 has negative optical power, and both its object-side and image-side surfaces are concave. The fourth lens E4 has positive optical power, and its object-side surface is convex. The fifth lens E5 has positive optical power, and both its object-side and image-side surfaces are concave. The sixth lens has negative optical power, and its image-side surface is concave.

[0055] The second lens group G2 includes a seventh lens E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, and a twelfth lens E12. The seventh lens E7 has positive optical power and its image-side surface is convex. The eighth lens E8 has negative optical power and its object-side surface is concave, as is its image-side surface. The ninth lens E9 has positive optical power and its image-side surface is convex. The tenth lens E10 has negative optical power and its object-side surface is concave, as is its image-side surface. The eleventh lens E11 has positive optical power and its image-side surface is convex. The twelfth lens E12 has positive optical power and its image-side surface is convex.

[0056] The second lens E2 and the third lens E3 are cemented together. The second lens group can move along the optical axis to achieve zoom. The lens group satisfies: 4.10≤f2 / CT2≤7.66, 8.00<FG2 / ΔL<10.15, where f2 is the effective focal length of the second lens, CT2 is the center thickness of the second lens, FG2 is the combined focal length of the second lens group, and ΔL is the distance the second lens group moves along the optical axis when the lens group changes from an infinite object distance state to a 1000mm object distance state.

[0057] For example, light from an object passes sequentially through the corresponding surfaces of the first lens group G1, the second lens group G2, and the imaging lens 20, and is finally imaged on the imaging surface IMG.

[0058] The following description, with reference to the accompanying drawings, further illustrates examples of the specific surface shape and parameters of the lens group 10 applicable to the above embodiments.

[0059] Example 1 The following is for reference Figures 2-5 The lens assembly 10 according to Embodiment 1 of this application is described. Figure 2 A schematic diagram of the lens assembly 10 in the first state according to Embodiment 1 of this application is shown. Figure 3 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 1 in the first state is shown. Figure 4 A schematic diagram of the lens assembly 10 in the second state of Embodiment 1 provided in this application is shown. Figure 5 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 1 in the second state is shown.

[0060] In the embodiments of this application, the first state is, for example, an infinite object distance state, and the second state is, for example, a 1000mm object distance state.

[0061] Example 1 includes 12 lenses. The effective focal lengths fq (at infinite object distance) and fw (at 1000mm object distance) of the optical system in Example 1 are both effective focal lengths when adapted to an imaging lens with a focal length of 22.48mm. The specific data for fq and fw in Example 1 are shown in the table below.

[0062] like Figure 2 and 4 As shown, the lens group 10 includes a first lens group G1 and a second lens group G2.

[0063] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens group G1 has positive optical power.

[0064] The first lens E1 has positive optical power, the object side S1 of the first lens E1 is convex, and the image side S2 of the first lens E1 is concave.

[0065] The second lens E2 has positive optical power. The object side S3 of the second lens E2 is convex, and the image side S4 of the second lens E2 is convex.

[0066] The third lens E3 has negative optical power. The object side S4 of the third lens E3 is concave, and the image side S5 of the third lens E3 is concave.

[0067] The fourth lens E4 has positive optical power, the object side S6 of the fourth lens E4 is convex, and the image side S7 of the fourth lens is concave.

[0068] The fifth lens E5 has positive optical power. The object side S8 of the fifth lens E5 is convex, and the image side S9 of the fifth lens E5 is concave.

[0069] The sixth lens E6 has negative optical power. The object side S10 of the sixth lens E6 is convex, and the image side S11 of the sixth lens E6 is concave.

[0070] The second lens group G2 includes the seventh lens E7, the eighth lens E8, the ninth lens E9, the tenth lens E10, the eleventh lens E11, and the twelfth lens E12. The second lens group G2 has positive optical power.

[0071] The seventh lens E7 has positive optical power. The object-side surface S12 of the seventh lens E7 is convex, and the image-side surface S13 of the seventh lens E7 is convex.

[0072] The eighth lens E8 has negative optical power. The object side S13 of the eighth lens E8 is concave, and the image side S14 of the eighth lens E8 is concave.

[0073] The ninth lens E9 has positive optical power. The object-side surface S15 of the ninth lens E9 is concave, and the image-side surface S16 of the ninth lens E9 is convex.

[0074] The tenth lens E10 has negative optical power. The object side S17 of the tenth lens E10 is concave, and the image side S18 of the tenth lens E10 is concave.

[0075] The eleventh lens E11 has positive optical power. The object-side surface S18 of the eleventh lens E11 is convex, and the image-side surface S19 of the eleventh lens E11 is convex.

[0076] The twelfth lens E12 has positive optical power. The object-side surface S20 of the twelfth lens E12 is convex, and the image-side surface S21 of the twelfth lens E12 is convex.

[0077] In this first embodiment, the second lens E2 and the third lens E3 are cemented together, the seventh lens E7 and the eighth lens E8 are cemented together, and the tenth lens E10 and the eleventh lens E11 are cemented together.

[0078] The basic parameters of the lens group 10 in the following embodiment are shown in Table 1. The values ​​of D1, D2 and D3 in Table 1 are shown in Table 2.

[0079] Table 1

[0080] Table 2

[0081] like Figure 3 As shown, the optical system described in Example 1 achieves good imaging quality in the first state. Figure 5 As shown, the optical system given in Example 1 can achieve good imaging quality in the second state.

[0082] Example 2 The following is for reference Figures 6-9 The lens assembly 10 according to Embodiment 2 of this application is described. Figure 6 A schematic diagram of the lens assembly 10 in the first state of Embodiment 2 provided in this application is shown. Figure 7 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 2 in the first state is shown. Figure 8 A schematic diagram of the lens assembly 10 in the second state of Embodiment 2 provided in this application is shown. Figure 9 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 2 in the second state is shown.

[0083] Example 2 includes 12 lenses. The effective focal lengths fq (at infinite object distance) and fw (at 1000mm object distance) of the optical system in Example 2 are both effective focal lengths when adapted to an imaging lens with a focal length of 22.48mm. The specific data for fq and fw in Example 2 are shown in the table below.

[0084] like Figure 6 and 8 As shown, the lens group 10 includes a first lens group G1 and a second lens group G2.

[0085] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens group G1 has positive optical power.

[0086] The first lens E1 has positive optical power, the object side S1 of the first lens E1 is convex, and the image side S2 of the first lens E1 is convex.

[0087] The second lens E2 has positive optical power. The object side S3 of the second lens E2 is convex, and the image side S4 of the second lens E2 is convex.

[0088] The third lens E3 has negative optical power. The object side S4 of the third lens E3 is concave, and the image side S5 of the third lens E3 is concave.

[0089] The fourth lens E4 has positive optical power, the object side S6 of the fourth lens E4 is convex, and the image side S7 of the fourth lens is convex.

[0090] The fifth lens E5 has positive optical power. The object side S8 of the fifth lens E5 is convex, and the image side S9 of the fifth lens E5 is concave.

[0091] The sixth lens E6 has negative optical power. The object side S10 of the sixth lens E6 is concave, and the image side S11 of the sixth lens E6 is concave.

[0092] The second lens group G2 includes the seventh lens E7, the eighth lens E8, the ninth lens E9, the tenth lens E10, the eleventh lens E11, and the twelfth lens E12. The second lens group G2 has positive optical power.

[0093] The seventh lens E7 has positive optical power. The object-side surface S12 of the seventh lens E7 is concave, and the image-side surface S13 of the seventh lens E7 is convex.

[0094] The eighth lens E8 has negative optical power. The object side S14 of the eighth lens E8 is concave, and the image side S15 of the eighth lens E8 is concave.

[0095] The ninth lens E9 has positive optical power. The object-side surface S16 of the ninth lens E9 is convex, and the image-side surface S17 of the ninth lens E9 is convex.

[0096] The tenth lens E10 has negative optical power. The object side S18 of the tenth lens E10 is concave, and the image side S19 of the tenth lens E10 is concave.

[0097] The eleventh lens E11 has positive optical power. The object-side surface S20 of the eleventh lens E11 is concave, and the image-side surface S21 of the eleventh lens E11 is convex.

[0098] The twelfth lens E12 has positive optical power. The object side surface S22 of the twelfth lens E12 is concave, and the image side surface S23 of the twelfth lens E12 is convex.

[0099] The second lens E2 and the third lens E3 are cemented together.

[0100] The basic parameters of lens group 10 in Embodiment 2 are shown in Table 3. The values ​​of D1, D2 and D3 in Table 3 are shown in Table 4.

[0101] Table 3

[0102] Table 4

[0103] like Figure 7 As shown, the optical system described in Embodiment 2 can achieve good imaging quality in the first state. Figure 9 As shown, the optical system given in Embodiment 2 can achieve good imaging quality in the second state.

[0104] Example 3 The following is for reference Figures 10-13 The lens assembly 10 according to Embodiment 3 of this application is described. Figure 10 A schematic diagram of the lens assembly 10 in the first state of Embodiment 3 provided in this application is shown. Figure 11 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 3 in the first state is shown. Figure 12 A schematic diagram of the lens assembly 10 in the second state of Embodiment 3 provided in this application is shown. Figure 13 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 3 in the second state is shown.

[0105] Example 3 includes 12 lenses. The effective focal lengths fq (at infinite object distance) and fw (at 1000mm object distance) of the optical system in Example 3 are both effective focal lengths when adapted to an imaging lens with a focal length of 22.48mm. The specific data for fq and fw in Example 3 are shown in the table below.

[0106] like Figure 10 and 12 As shown, the lens group 10 includes a first lens group G1 and a second lens group G2.

[0107] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens group G1 has positive optical power.

[0108] The first lens E1 has positive optical power, the object side S1 of the first lens E1 is convex, and the image side S2 of the first lens E1 is convex.

[0109] The second lens E2 has positive optical power. The object side S3 of the second lens E2 is convex, and the image side S4 of the second lens E2 is convex.

[0110] The third lens E3 has negative optical power. The object side S4 of the third lens E3 is concave, and the image side S5 of the third lens E3 is concave.

[0111] The fourth lens E4 has positive optical power, the object side S6 of the fourth lens E4 is convex, and the image side S7 of the fourth lens is convex.

[0112] The fifth lens E5 has positive optical power. The object side S8 of the fifth lens E5 is convex, and the image side S9 of the fifth lens E5 is concave.

[0113] The sixth lens E6 has negative optical power. The object side S10 of the sixth lens E6 is concave, and the image side S11 of the sixth lens E6 is concave.

[0114] The second lens group G2 includes the seventh lens E7, the eighth lens E8, the ninth lens E9, the tenth lens E10, the eleventh lens E11, and the twelfth lens E12. The second lens group G2 has positive optical power.

[0115] The seventh lens E7 has positive optical power. The object-side surface S12 of the seventh lens E7 is concave, and the image-side surface S13 of the seventh lens E7 is convex.

[0116] The eighth lens E8 has negative optical power. The object side S14 of the eighth lens E8 is concave, and the image side S15 of the eighth lens E8 is concave.

[0117] The ninth lens E9 has positive optical power. The object-side surface S16 of the ninth lens E9 is convex, and the image-side surface S17 of the ninth lens E9 is convex.

[0118] The tenth lens E10 has negative optical power. The object side S18 of the tenth lens E10 is concave, and the image side S19 of the tenth lens E10 is concave.

[0119] The eleventh lens E11 has positive optical power, and the object-side surface S19 of the eleventh lens E11 is convex; the image-side surface S20 of the eleventh lens E11 is convex.

[0120] The twelfth lens E12 has positive optical power. The object side S21 of the twelfth lens E12 is concave, and the image side S22 of the twelfth lens E12 is convex.

[0121] The second lens E2 and the third lens E3 are cemented together, and the tenth lens E10 and the eleventh lens E11 are cemented together.

[0122] The basic parameters of lens group 10 in Embodiment 3 are shown in Table 5. The values ​​of D1, D2 and D3 in Table 5 are shown in Table 6.

[0123] Table 5

[0124] Table 6

[0125] like Figure 11 As shown, the optical system described in Embodiment 3 can achieve good imaging quality in the first state. Figure 13 As shown, the optical system given in Embodiment 3 can achieve good imaging quality in the second state.

[0126] Example 4 The following is for reference Figures 14-17 The lens assembly 10 according to Embodiment 4 of this application is described. Figure 14 A schematic diagram of the lens assembly 10 in the first state of Embodiment 4 provided in this application is shown. Figure 15 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 4 in the first state is shown. Figure 16 A schematic diagram of the lens assembly 10 in the second state of Embodiment 4 provided in this application is shown. Figure 17 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 4 in the second state is shown.

[0127] Example 4 includes 12 lenses. The effective focal lengths fq (at infinite object distance) and fw (at 1000mm object distance) of the optical system in Example 4 are both effective focal lengths when adapted to an imaging lens with a focal length of 22.48mm. The specific data for fq and fw in Example 4 are shown in the table below.

[0128] like Figure 14 and 16 As shown, the lens group 10 includes a first lens group G1 and a second lens group G2.

[0129] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens group G1 has positive optical power.

[0130] The first lens E1 has positive optical power, the object side S1 of the first lens E1 is convex, and the image side S2 of the first lens E1 is convex.

[0131] The second lens E2 has positive optical power. The object side S3 of the second lens E2 is convex, and the image side S4 of the second lens E2 is convex.

[0132] The third lens E3 has negative optical power. The object side S4 of the third lens E3 is concave, and the image side S5 of the third lens E3 is concave.

[0133] The fourth lens E4 has positive optical power, the object side S6 of the fourth lens E4 is convex, and the image side S7 of the fourth lens is convex.

[0134] The fifth lens E5 has positive optical power. The object side S8 of the fifth lens E5 is convex, and the image side S9 of the fifth lens E5 is concave.

[0135] The sixth lens E6 has negative optical power. The object side S10 of the sixth lens E6 is concave, and the image side S11 of the sixth lens E6 is concave.

[0136] The second lens group G2 includes the seventh lens E7, the eighth lens E8, the ninth lens E9, the tenth lens E10, the eleventh lens E11, and the twelfth lens E12. The second lens group G2 has positive optical power.

[0137] The seventh lens E7 has positive optical power. The object-side surface S12 of the seventh lens E7 is convex, and the image-side surface S13 of the seventh lens E7 is convex.

[0138] The eighth lens E8 has negative optical power. The object side S13 of the eighth lens E8 is concave, and the image side S14 of the eighth lens E8 is concave.

[0139] The ninth lens E9 has positive optical power. The object-side surface S15 of the ninth lens E9 is convex, and the image-side surface S16 of the ninth lens E9 is convex.

[0140] The tenth lens E10 has negative optical power. The object side S17 of the tenth lens E10 is concave, and the image side S18 of the tenth lens E10 is concave.

[0141] The eleventh lens E11 has positive optical power. The object-side surface S18 of the eleventh lens E11 is convex, and the image-side surface S19 of the eleventh lens E11 is convex.

[0142] The twelfth lens E12 has positive optical power. The object-side surface S20 of the twelfth lens E12 is concave, and the image-side surface S21 of the twelfth lens E12 is convex.

[0143] The second lens E2 and the third lens E3 are cemented together, the seventh lens E7 and the eighth lens E8 are cemented together, and the tenth lens E10 and the eleventh lens E11 are cemented together.

[0144] The basic parameters of lens group 10 in Embodiment 4 are shown in Table 7. The values ​​of D1, D2 and D3 in Table 7 are shown in Table 8.

[0145] Table 7

[0146] Table 8

[0147] like Figure 15 As shown, the optical system described in Embodiment 4 achieves good imaging quality in the first state. Figure 17 As shown, the optical system given in Embodiment 4 can achieve good imaging quality in the second state.

[0148] Example 5 The following is for reference Figures 18-21 The lens assembly 10 according to Embodiment 5 of this application is described. Figure 18 A schematic diagram of the lens assembly 10 of Embodiment 5 provided in this application in the first state is shown. Figure 19 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 5 in the first state is shown. Figure 20 A schematic diagram of the lens assembly 10 in the second state of Embodiment 5 provided in this application is shown. Figure 21 A schematic diagram of the on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system of Embodiment 5 in the second state is shown.

[0149] Example 5 includes 12 lenses. The effective focal lengths fq (at infinite object distance) and fw (at 1000mm object distance) of the optical system in Example 5 are both effective focal lengths when adapted to an imaging lens with a focal length of 22.48mm. The specific data for fq and fw in Example 5 are shown in the table below.

[0150] like Figure 18 and 20 As shown, the lens group 10 includes a first lens group G1 and a second lens group G2.

[0151] The first lens group G1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, and a sixth lens E6. The first lens group G1 has positive optical power.

[0152] The first lens E1 has positive optical power, the object side S1 of the first lens E1 is convex, and the image side S2 of the first lens E1 is concave.

[0153] The second lens E2 has positive optical power. The object side S3 of the second lens E2 is convex, and the image side S4 of the second lens E2 is convex.

[0154] The third lens E3 has negative optical power. The object side S4 of the third lens E3 is concave, and the image side S5 of the third lens E3 is concave.

[0155] The fourth lens E4 has positive optical power, the object side S6 of the fourth lens E4 is convex, and the image side S7 of the fourth lens is convex.

[0156] The fifth lens E5 has positive optical power. The object side S8 of the fifth lens E5 is convex, and the image side S9 of the fifth lens E5 is concave.

[0157] The sixth lens E6 has negative optical power. The object side S10 of the sixth lens E6 is concave, and the image side S11 of the sixth lens E6 is concave.

[0158] The second lens group G2 includes the seventh lens E7, the eighth lens E8, the ninth lens E9, the tenth lens E10, the eleventh lens E11, and the twelfth lens E12. The second lens group G2 has positive optical power.

[0159] The seventh lens E7 has positive optical power. The object-side surface S12 of the seventh lens E7 is concave, and the image-side surface S13 of the seventh lens E7 is convex.

[0160] The eighth lens E8 has negative optical power. The object side S14 of the eighth lens E8 is concave, and the image side S15 of the eighth lens E8 is concave.

[0161] The ninth lens E9 has positive optical power. The object-side surface S15 of the ninth lens E9 is convex, and the image-side surface S16 of the ninth lens E9 is convex.

[0162] The tenth lens E10 has negative optical power. The object side S17 of the tenth lens E10 is concave, and the image side S18 of the tenth lens E10 is concave.

[0163] The eleventh lens E11 has positive optical power. The object-side surface S18 of the eleventh lens E11 is convex, and the image-side surface S19 of the eleventh lens E11 is convex.

[0164] The twelfth lens E12 has positive optical power. The object-side surface S20 of the twelfth lens E12 is concave, and the image-side surface S21 of the twelfth lens E12 is convex.

[0165] The second lens E2 and the third lens E3 are cemented together, the eighth lens E8 and the ninth lens E9 are cemented together, and the tenth lens E10 and the eleventh lens E11 are cemented together.

[0166] The basic parameters of lens group 10 in Embodiment 5 are shown in Table 9. The values ​​of D1, D2 and D3 in Table 9 are shown in Table 10.

[0167] Table 9

[0168] Table 10

[0169] like Figure 19 As shown, the optical system described in Embodiment 5 achieves good imaging quality in the first state. Figure 21 As shown, the optical system given in Embodiment 5 can achieve good imaging quality in the second state.

[0170] Some optical parameters of Examples 1 to 5 are shown in Table 11 (unit: mm). The conditions satisfied by Examples 1 to 5 are shown in Table 12.

[0171] Table 11

[0172] Table 12

[0173] In addition, this application also provides an optical system including a lens group provided in any embodiment of this application.

[0174] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of protection involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the concept of this application. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A lens assembly, wherein the lens assembly comprises, sequentially from the object side to the image side along the optical axis, a first lens assembly and a second lens assembly, characterized in that, The first lens group has positive optical power, and the first lens group includes: A first lens having positive optical power, wherein the object side of the first lens is convex; A second lens with positive optical power, wherein the object-side surface of the second lens is convex and the image-side surface of the second lens is convex; A third lens with negative optical power, wherein the object-side surface of the third lens is concave and the image-side surface of the third lens is concave. A fourth lens with positive optical power, wherein the object side of the fourth lens is convex; A fifth lens with positive optical power, wherein the object-side surface of the fifth lens is convex and the image-side surface of the fifth lens is concave; A sixth lens with negative optical power, wherein the image-side surface of the sixth lens is concave; The second lens group has positive optical power, and the second lens group includes: A seventh lens with positive optical power, wherein the image-side surface of the seventh lens is convex; An eighth lens with negative optical power, wherein the object-side surface of the eighth lens is concave and the image-side surface of the eighth lens is concave. A ninth lens having positive optical power, wherein the image-side surface of the ninth lens is convex; A tenth lens with negative optical power, wherein the object side of the tenth lens is concave and the image side of the tenth lens is concave. An eleventh lens with positive optical power, wherein the image-side surface of the eleventh lens is convex; A twelfth lens with positive optical power, wherein the image-side surface of the twelfth lens is convex; The second lens and the third lens are cemented together, and the second lens group can move along the optical axis to achieve zoom. The lens group satisfies: 4.10≤f2 / CT2≤7.66, 8.00<FG2 / ΔL<10.15, where f2 is the effective focal length of the second lens, CT2 is the center thickness of the second lens, FG2 is the combined focal length of the second lens group, and ΔL is the distance the second lens group moves along the optical axis when the lens group changes from an infinite object distance state to a 1000mm object distance state.

2. The lens assembly according to claim 1, characterized in that, The lens group satisfies: -1.70 < f1 / F23 < -0.75, where f1 is the effective focal length of the first lens and F23 is the combined focal length of the second and third lenses.

3. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 0.95<LG1 / FG1≤1.45, where LG1 is the axial distance from the object side of the first lens to the image side of the sixth lens, and FG1 is the combined focal length of the first lens group.

4. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 5.65 < F1234 / T45 < 6.35, where F1234 is the combined focal length of the first lens, the second lens, the third lens, and the fourth lens, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

5. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 1.70 < R6 / (CT2+CT3) ≤ 2.90, where R6 is the radius of curvature of the image side of the third lens and CT3 is the center thickness of the third lens.

6. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 7.30 < F789 / ΔL < 9.75, where F789 is the combined focal length of the seventh lens, the eighth lens, and the ninth lens.

7. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 1.40 < F101112 / ∑CTG2 < 2.20, where F101112 is the combined focal length of the tenth lens, the eleventh lens and the twelfth lens, and ∑CTG2 is the sum of the center thicknesses of all lenses from the seventh lens to the twelfth lens.

8. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 0.80 < LG2 / f12 ≤ 1.15, where LG2 is the axial distance from the object side of the seventh lens to the image side of the twelfth lens, and f12 is the effective focal length of the twelfth lens.

9. The lens assembly according to claim 1, characterized in that, The lens group satisfies: -1.35 < R22 / f11 < -0.70, where R22 is the radius of curvature of the image side of the eleventh lens, and f11 is the effective focal length of the eleventh lens.

10. The lens assembly according to claim 1, characterized in that, The lens group satisfies: -3.60 < (f5 × N5) / (f6 × N6) < -0.55, where f5 is the effective focal length of the fifth lens, N5 is the refractive index of the fifth lens, f6 is the effective focal length of the sixth lens, and N6 is the refractive index of the sixth lens.

11. The lens assembly according to claim 1, characterized in that, The lens group satisfies: -10.22≤F1011 / (CT10+CT11)≤-3.86, where F1011 is the combined focal length of the tenth lens and the eleventh lens, CT10 is the center thickness of the tenth lens, and CT11 is the center thickness of the eleventh lens.

12. The lens assembly according to claim 1, characterized in that, The lens group satisfies: 1.10 < f4 / ∑CTG1 < 2.60, where f4 is the effective focal length of the fourth lens and ∑CTG1 is the sum of the center thicknesses of all lenses from the first lens to the sixth lens.

13. The lens assembly according to claim 1, characterized in that, The lens group satisfies: -7.75≤R24 / CT12<-5.10, where R24 is the radius of curvature of the image side surface of the twelfth lens, and CT12 is the center thickness of the twelfth lens.

14. An optical system, characterized in that, include: The lens assembly according to any one of claims 1-13; An imaging lens located on the image side of the twelfth lens; as well as Imaging plane, The beam emitted from the lens group enters the imaging lens to form an image on the imaging plane. The optical system satisfies: 16.25≤TDq / Δf≤19.98, where TDq is the axial distance between the object side of the first lens and the image side of the twelfth lens when the lens group is in the infinite object distance state, and Δf is the change in effective focal length of the optical system when the object distance changes from the infinite object distance state to the 1000mm object distance state.

15. The optical system according to claim 14, characterized in that, The optical system satisfies: 1.95≤Δf / ΔL<3.00, where Δf is the change in effective focal length of the optical system when it changes from the infinite object distance state to the 1000mm object distance state.

Images