Optical system

Abstract

The present application relates to an optical system, comprising a first lens barrel, a second lens barrel, a first lens group, a second lens group, a plurality of spacer elements, the first lens group is arranged in the first lens barrel, the second lens group is arranged in the second lens barrel; the second lens group is arranged on the image side of the first lens group, and the second lens group is movable along the optical axis direction; the first lens group comprises a first lens to a fourth lens, and the second lens group comprises a fifth lens to a seventh lens; the plurality of spacer elements at least comprises a first spacer element and a second spacer element. The optical system satisfies: 6.60

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and more particularly to an optical system. Background Technology

[0002] With the increasing demand for photography, the diversification of shooting needs is becoming more and more pronounced. Different shooting scenarios often require different lens specifications. Telephoto lenses are suitable for shooting distant portraits and landscapes, and their optical characteristics can achieve background blur to highlight the subject. Building on this, the innovation of internal focusing technology has provided photographers with unprecedented flexibility: by adjusting the relative positions between lens groups, the focal length can be changed without moving the entire lens structure, thus greatly expanding the application range of a single lens and meeting the requirements of various scenarios.

[0003] Internal focusing lenses have a relatively large air gap inside. When light passes through different media, a well-designed air gap can effectively separate spectral components, reduce purple fringing and chromatic aberration, and optimize chromatic aberration, thereby improving image sharpness and color reproduction accuracy, resulting in better image quality. However, in the design of internal focusing lenses, a larger air gap can also cause problems with stray light and ghosting.

[0004] Therefore, how to solve stray light by properly setting the relationship between the lens and the spacer element is an urgent problem to be solved. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide an optical system that meets the design requirements of telephoto lenses while effectively reducing stray light risks and improving image quality.

[0006] To achieve the above-mentioned objectives, the present invention provides an optical system comprising a first lens barrel, a second lens barrel, a first lens group, a second lens group, and a plurality of spacer elements, wherein the first lens group is disposed within the first lens barrel, and the second lens group is disposed within the second lens barrel; the second lens group is disposed on the image side of the first lens group, and the second lens group is movable along the optical axis.

[0007] The first lens group includes, in sequence along the optical axis from the object side to the image side, a first lens with positive optical power, a second lens with optical power, a third lens with optical power, and a fourth lens with positive optical power, for a total of four lenses with optical power.

[0008] The second lens group includes, in sequence along the optical axis from the object side to the image side, a fifth lens with optical power, a sixth lens with optical power, and a seventh lens with negative optical power, for a total of three lenses with optical power.

[0009] The plurality of spacer elements include:

[0010] A first spacer element is disposed on the image side of the first lens and contacts the image side of the first lens;

[0011] The second spacer element is disposed on the image side of the second lens and contacts the image side of the second lens;

[0012] The optical system satisfies:

[0013] 6.60 <FNOb / TAN(Semi-FOVb)<10.00;

[0014] 2.95 <L1 / T12<5.35;

[0015] 0.9 < (EP12 + CP1) / EP01 < 1.75;

[0016] Wherein, T12 is the air gap between the first lens and the second lens on the optical axis, CP1 is the maximum thickness of the first spacer element along the optical axis, EP12 is the spacing distance between the first spacer element and the second spacer element along the optical axis, EP01 is the spacing distance between the object-side end face of the first lens barrel and the object-side face of the first spacer element along the optical axis, FNOb is the aperture number of the optical system at the close-up position, Semi-FOVb is half of the maximum field of view of the optical system at the close-up position, and L1 is the maximum height of the first lens barrel.

[0017] According to one technical solution of the present invention, the optical system satisfies: 1.30 <fa / fb<1.45;1.70<L1 / L2≤2.05;

[0018] Wherein, fa is the effective focal length of the optical system at the far shooting position, fb is the effective focal length of the optical system at the close shooting position, L1 is the maximum height of the first lens barrel, and L2 is the maximum height of the second lens barrel.

[0019] According to one technical solution of the present invention, the optical powers of the second lens and the third lens are opposite in sign; the optical powers of the fifth lens and the sixth lens are opposite in sign; the optical system satisfies: 2.15 <F1 / fa / tan(Semi-FOVa)≤2.60;

[0020] Where F1 is the effective focal length of the first lens group, fa is the effective focal length of the optical system at the telephoto position, and Semi-FOVa is half of the maximum field of view of the optical system at the telephoto position.

[0021] According to one technical solution of the present invention, the optical system satisfies: 1.00 <F1 / L1<1.45;-2.70<F2 / L2<-2.00;

[0022] Wherein, F1 is the effective focal length of the first lens group, L1 is the maximum height of the first lens barrel, F2 is the effective focal length of the second lens group, and L2 is the maximum height of the second lens barrel.

[0023] According to one technical solution of the present invention, the optical system satisfies:

[0024] 4.20mm <F1 / (N1+N2)<4.90mm;0.55<EP01 / EP12≤1.10;

[0025] Wherein, F1 is the effective focal length of the first lens group, N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, EP01 is the distance along the optical axis from the object-side end face of the first lens barrel to the object-side surface of the first spacer element, and EP12 is the distance along the optical axis between the first spacer element and the second spacer element.

[0026] According to one technical solution of the present invention, the optical system satisfies:

[0027] -4.70 <F2 / (d02m-d02smin)<-3.60;

[0028] Where F2 is the effective focal length of the second lens group, d02m is the inner diameter of the image-side end face of the second lens barrel, and d02smin is the minimum aperture of the object-side end of the second lens barrel.

[0029] According to one technical solution of the present invention, the plurality of spacers further includes a first auxiliary spacer element disposed on the image side of the first spacer element and in contact with the image side side of the first spacer element;

[0030] The optical system satisfies: 0.65 ≤ (EP12 - CP1b) / CT2 < 1.95;

[0031] Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CP1b is the maximum thickness of the first auxiliary spacer element along the optical axis, and CT2 is the center thickness of the second lens.

[0032] According to one technical solution of the present invention, the plurality of spacers further includes a fifth spacer element disposed on the image side of the fifth lens and in contact with the image side of the fifth lens, and a sixth spacer element disposed on the image side of the sixth lens and in contact with the image side of the sixth lens;

[0033] The optical system includes: 0.25 <EP56 / L2<0.40;

[0034] Wherein, EP56 is the distance between the fifth spacer element and the sixth spacer element along the optical axis, and L2 is the maximum height of the second lens barrel.

[0035] According to one technical solution of the present invention, the optical system satisfies: 0.70 <CT6 / (CT5+CT7)≤1.5;0.40<EP56 / (D6m-d6s)<0.85;

[0036] Wherein, CT6 is the center thickness of the sixth lens, CT5 is the center thickness of the fifth lens, CT7 is the center thickness of the seventh lens, EP56 is the spacing distance between the fifth spacer element and the sixth spacer element along the optical axis, D6m is the outer diameter of the image side of the sixth spacer element, and d6s is the inner diameter of the object side of the sixth spacer element.

[0037] According to one technical solution of the present invention, the optical system satisfies: 3.60 <R12 / CT6<7.95;1.35<D6m / d5s<1.65;

[0038] Wherein, R12 is the radius of curvature of the image side of the sixth lens, CT6 is the center thickness of the sixth lens, D6m is the outer diameter of the image side of the sixth spacer element, and d5s is the inner diameter of the object side of the fifth spacer element.

[0039] According to one technical solution of the present invention, the optical system satisfies: 1.25 <d02m / d6s<1.60;

[0040] Wherein, d02m is the inner diameter of the image-side end face of the second lens tube, and d6s is the inner diameter of the object-side end face of the sixth spacer element.

[0041] The beneficial effects of this invention are:

[0042] The optical system of the present application is a telephoto lens, and satisfies 6.60 < FNOb / TAN(Semi-FOVb) < 10.00, 2.95 < L1 / T12 < 5.35. In order to correct aberrations and ensure the stability of aberrations during the focusing process in the above optical system, the air gap between the first lens and the second lens is relatively large, resulting in internal reflection when off-axis light passes through the first lens and the air gap and then through the second lens. After the light is reflected twice in the non-light-passing area of the second lens, it cannot be effectively absorbed by the spacer element, thereby generating stray light and ghost images. By restricting the relationship between the distance between the object-side end face of the first lens barrel and the object side of the first spacer element, the distance between the first spacer element and the second spacer element, and the maximum thickness of the first spacer element along the optical axis direction, and further restricting the thickness of the spacer element between the first lens and the second lens and the thickness of the non-light-passing area of the second lens, the reflection position of the light in the second lens can be adjusted to change the light path. At the same time, by reasonably setting the thickness of the non-light-passing area of the second lens, multiple reflections can occur in the non-light-passing area of the lens, causing the light energy to decay, effectively suppressing the stray light generated in the second lens, and thereby effectively improving the imaging effect of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 Shows a schematic diagram of the structural arrangement and some parameters of an optical system according to the present invention;

[0045] Figure 2A 、 Figure 2B and Figure 2C Shows schematic diagrams of the structures of three optical systems according to Embodiment 1 of the present application;

[0046] Figure 3 Shows schematic diagrams of the optical structures of the optical system according to Embodiment 1 of the present application at the telephoto position and the close-up position;

[0047] Figure 4A 、 Figure 4B and Figure 4C Respectively show the axial chromatic aberration curve, astigmatism curve and distortion curve of the optical system according to Embodiment 1 of the present application at the telephoto position; <00​​​​​​The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 1 of this application are shown at the close-up position.

[0049] Figure 6A , Figure 6B and Figure 6C Schematic diagrams of three optical systems according to Embodiment 2 of this application are shown;

[0050] Figure 7 A schematic diagram of the optical structure of the optical system according to Embodiment 2 of this application is shown in both the far-field and close-field positions.

[0051] Figure 8A , Figure 8B and Figure 8C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 2 of this application are shown at the far shooting position, respectively.

[0052] Figure 9A , Figure 9B and Figure 9C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 2 of this application are shown at the close-up position, respectively.

[0053] Figure 10A , Figure 10B and Figure 10C Schematic diagrams of three optical systems according to Embodiment 3 of this application are shown;

[0054] Figure 11 A schematic diagram of the optical structure of the optical system according to Embodiment 3 of this application is shown in both the far-field and close-field positions.

[0055] Figure 12A , Figure 12B and Figure 12C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 3 of this application are shown at the far shooting position, respectively.

[0056] Figure 13A , Figure 13B and Figure 13C The on-axis chromatic aberration curve, astigmatism curve, and distortion curve of the optical system according to Embodiment 3 of this application are shown at the close-up position.

[0057] Figure 14A and 14B The optical path diagram and spot diagram are shown when the optical system satisfies: FNOb / TAN(Semi-FOVb)=7.23, L1 / T12=4.5, (EP12+CP1) / EP01=0.7;

[0058] Figure 15A and15B The optical path diagram and spot diagram are shown when the optical system satisfies: FNOb / TAN(Semi-FOVb)=7.23, L1 / T12=4.5, (EP12+CP1) / EP01=1.43;

[0059] Figure 16A and 16B The optical path diagram and spot diagram are shown when the optical system satisfies: FNOb / TAN(Semi-FOVb)=7.23, L1 / T12=4.5, (EP12+CP1) / EP01=1.82. Detailed Implementation

[0060] 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.

[0061] It should be noted that in this specification, the terms "first," "second," "third," 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 or the third lens, or the first lens may also be referred to as the first lens.

[0062] 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.

[0063] 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. The surface shape in the paraxial region can be determined by the sign of the R value (R refers to the radius of curvature of the paraxial region). In this paper, the side where the image to be imaged is located is called the object side, and the side where the image of the image to be imaged is located is called the image side. The surface of each lens near the object side is called the object-side surface of the lens, and the surface of each lens near the image side is called the image-side surface of the lens. Each object-side or image-side surface of a lens has an optical region and a structural region. The optical region refers to the light-transmitting region, and the structural region refers to the non-light-transmitting region. For the object-side surface, when the R value is positive, it is determined to be convex, and when the R value is negative, it is determined to be concave. For the image-side surface, when the R value is positive, it is determined to be concave, and when the R value is negative, it is determined to be convex.

[0064] 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.

[0065] 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 the 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.

[0066] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other. The following embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application.

[0067] like Figure 1As shown, according to a first aspect of this application, an optical system is provided, including a first lens barrel, a second lens barrel, a first lens group, a second lens group, and a plurality of spacer elements. The first lens group is placed inside the first lens barrel, and the second lens group is placed inside the second lens barrel. The second lens group is placed on the image side of the first lens group and is movable along the optical axis.

[0068] The first lens group includes, in sequence along the optical axis from the object side to the image side, a first lens with positive optical power, a second lens with optical power, a third lens with optical power, and a fourth lens with positive optical power; the optical powers of the second lens and the third lens are opposite in sign.

[0069] The second lens group includes, in sequence along the optical axis from the object side to the image side, a fifth lens with optical power, a sixth lens with optical power, and a seventh lens with negative optical power; the optical powers of the fifth lens and the sixth lens are opposite in sign.

[0070] The plurality of spacers includes at least: a first spacer element disposed on the image side of the first lens and in contact with the image side of the first lens; a first auxiliary spacer element disposed on the image side of the first spacer element and in contact with the image side of the first spacer element; a second spacer element disposed on the image side of the second lens and in contact with the image side of the second lens; a fifth spacer element disposed on the image side of the fifth lens and in contact with the image side of the fifth lens; and a sixth spacer element disposed on the image side of the sixth lens and in contact with the image side of the sixth lens. At least two spacers are disposed between the first lens and the second lens: the first spacer element and the first auxiliary spacer element.

[0071] Both the first and second lens tubes include an object-side end face, an image-side end face, an outer ring surface, and an inner ring surface. Along the optical axis of the optical system, the inner ring surface of the lens tube is stepped.

[0072] In some embodiments of the present invention, the optical system may further include color filters for correcting color deviations and / or protective glass for protecting the photosensitive element located on the imaging surface.

[0073] In some embodiments of the present invention, the optical system satisfies:

[0074] 6.60 <FNOb / TAN(Semi-FOVb)<10.00;2.95<L1 / T12<5.35;

[0075] 0.9 < (EP12 + CP1) / EP01 < 1.75; where T12 is the air gap between the first lens and the second lens on the optical axis, CP1 is the maximum thickness of the first spacer element along the optical axis direction, EP12 is the spacer distance between the first spacer element and the second spacer element along the optical axis direction, EP01 is the spacer distance between the object-side end face of the first lens barrel and the object-side surface of the first spacer element along the optical axis direction, FNOb is the aperture number of the optical system at the close-up position, Semi-FOVb is half of the maximum field angle of the optical system at the close-up position, and L1 is the maximum height of the first lens barrel.

[0076] For the optical system in this application, it satisfies 6.60 < FNOb / TAN(Semi-FOVb) < 10.00 and 2.95 < L1 / T12 < 5.35, and has long focal length technical characteristics. To correct aberrations and ensure the stability of aberrations during the focusing process, there is a large air gap between the first lens and the second lens. This also causes internal reflection to occur when off-axis light passes through the first lens and the air gap and then through the second lens. After the light is reflected twice in the non-light-passing area of the second lens, it cannot be effectively absorbed by the spacer element, resulting in stray light and ghost images. By restricting the relationship between the spacer distance between the object-side end face of the first lens barrel and the object-side surface of the first spacer element, the spacer distance between the first spacer element and the second spacer element, and the maximum thickness of the first spacer element along the optical axis direction, the thickness of the spacer element between the first lens and the second lens and the thickness of the non-light-passing area of the second lens are restricted. Appropriately advancing or delaying the refraction position of the light in the second lens changes the light path, and the reasonable thickness of the non-light-passing area of the second lens causes the light path to be reflected multiple times in the lens, resulting in energy attenuation of the light, effectively suppressing the stray light generated in the second lens.

[0077] For example, referring to Figures 14A to 16B As shown, when the optical system satisfies FNOb / TAN(Semi-FOVb) = 7.23 and L1 / T12 = 4.5, and (EP12 + CP1) / EP01 = 0.7 is set, as Figure 14A and 14B shown, in this case, the light path of the optical system is a total reflection light path, and the energy loss of the stray light after multiple reflections is small. After the light is reflected in the non-light-passing area and then reflected twice on the light-passing object-side surface of the second lens, there are较多 light spots around the final spot pattern, and the risk of lens stray light is较大; when (EP12 + CP1) / EP01 = 1.43 is set, the above relationship is satisfied, as Figure 15A and 15B shown, in this case, the stray light path of the optical system passes through the atomized position at the edge of the lens, the light energy is dispersed, and after passing through the non-light-passing area of the second lens and being reflected multiple times, it directly exits. The simulation effect of the stray light on the final image plane is relatively ideal; when (EP12 + CP1) / EP01 = 1.82, as Figure 16A and 16B As shown, in this case, the optical path of the optical system is a total reflection optical path with no energy loss. The spacer element cannot effectively block light, and there are obvious arc-shaped light spots in the spot pattern, resulting in a relatively high risk of lens stray light. It can be seen that when the optical system satisfies the range of 6.60 < FNOb / TAN(Semi-FOVb) < 10.00 and 0.9 < (EP12 + CP1) / EP01 < 1.75, it can effectively improve stray light and enhance the imaging quality.

[0078] In some embodiments of the present invention, the optical system satisfies: 1.30 < fa / fb < 1.45; 1.70 < L1 / L2 ≤ 2.05; where fa is the effective focal length of the optical system at the telephoto position, fb is the effective focal length of the optical system at the close-up position, L1 is the maximum height of the first lens barrel, and L2 is the maximum height of the second lens barrel.

[0079] When the above conditional expressions are satisfied, the length distribution of the two lens groups is reasonably allocated. While meeting the focal length change requirements, it ensures that the overall length of the lens group is relatively moderate, the overall volume of the lens is relatively appropriate, and the weight of the imaging lens can be minimized as much as possible.

[0080] In some embodiments of the present invention, the optical system satisfies: 2.15 < F1 / fa / tan(Semi-FOVa) ≤ 2.60; where F1 is the effective focal length of the first lens group, fa is the effective focal length of the optical system at the telephoto position, and Semi-FOVa is half of the maximum field angle of the optical system at the telephoto position.

[0081] By constraining the relationship between the effective focal length of the first lens group of the optical system, the effective focal length at the telephoto position, and half of the field angle, it ensures the imaging clarity of the entire focal length range from infinity to a 120 mm object distance of the lens, reduces the image plane shift and off-axis aberration accumulation during the focusing process, and at the same time ensures that the field angle is not too small when the optical system is at a long focal length, affecting the imaging effect.

[0082] In some embodiments of the present invention, the optical system satisfies: 1.00 < F1 / L1 < 1.45;

[0083] -2.70 < F2 / L2 < -2.00; where F1 is the effective focal length of the first lens group, L1 is the maximum height of the first lens barrel, F2 is the effective focal length of the second lens group, and L2 is the maximum height of the second lens barrel.

[0084] By constraining the ratio of the effective focal length of the first lens group to the maximum height of the first lens barrel and the ratio of the effective focal length of the second lens group to the maximum height of the second lens barrel, it is beneficial to control the overall length of the optical system and the gap between the lenses, avoiding the optical system from being too large in volume.

[0085] In some embodiments of the present invention, the optical system satisfies:

[0086] 4.20mm < F1 / (N1 + N2) < 4.90mm; 0.55 < EP01 / EP12 ≤ 1.10; where F1 is the effective focal length of the first lens group, N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, EP01 is the distance along the optical axis from the object-side end face of the first lens barrel to the object-side surface of the first spacer element, and EP12 is the distance along the optical axis between the first spacer element and the second spacer element.

[0087] By reasonably setting the relationship between the refractive indices of the first lens and the second lens and the effective focal length of the first lens group, the risk of total reflection of light rays between the first lens and the second lens can be effectively reduced. Further, by reasonably setting the distance between the object-side end face of the first lens barrel and the object-side surface of the first spacer element, and the distance between the first spacer element and the second spacer element, the thickness of the non-light-transmitting regions of the first lens and the second lens can be constrained, thereby limiting the number of reflections of light rays in the non-light-transmitting regions of the first lens and the second lens, and reducing the risk of internal stray light in the first lens and the second lens.

[0088] In some embodiments of the present invention, the optical system satisfies:

[0089] -4.70 < F2 / (d02m - d02smin) < -3.60; where F2 is the effective focal length of the second lens group, d02m is the inner diameter of the image-side end face of the second lens barrel, and d02smin is the minimum aperture of the object-side end of the second lens barrel.

[0090] When the above conditional formula is satisfied, constraining the relationship between the effective focal length of the second lens group and the aperture of the incident and outgoing light rays of the lens barrel is beneficial for the light ray angles and the light ray convergence trend of the incident and outgoing light rays of the second lens group to meet the design requirements, and by constraining the inner diameter relationship before and after the lens barrel, it is ensured that the volume of the lens barrel will not be too large to cause the lens weight to be overweight.

[0091] In some embodiments of the present invention, the plurality of spacer elements further includes a first auxiliary spacer element disposed on the image side of the first spacer element and in contact with the image-side surface of the first spacer element; the optical system satisfies: 0.65 ≤ (EP12 - CP1b) / CT2 < 1.95; where EP12 is the distance along the optical axis between the first spacer element and the second spacer element, CP1b is the maximum thickness of the first auxiliary spacer element along the optical axis, and CT2 is the central thickness of the second lens.

[0092] By constraining the relationship between the distance between the first spacer element and the second spacer element, and the relationship between the maximum thickness of the first auxiliary spacer element along the optical axis direction and the central thickness of the second lens to satisfy the above conditional formula, it is beneficial to constrain the ratio of the non-light-passing area of the second lens to the central thickness of the second lens within a reasonable range, thereby improving the forming accuracy of the second lens.

[0093] In some embodiments of the present invention, the optical system includes: 0.25 < EP56 / L2 < 0.40; where EP56 is the distance between the fifth spacer element and the sixth spacer element along the optical axis direction, and L2 is the maximum height of the second lens barrel.

[0094] By constraining the ratio of the distance between the fifth spacer element and the sixth spacer element to the maximum height of the second lens barrel, it is beneficial to achieve a reasonable setting of the maximum thickness of the non-light-passing area of the sixth lens, and increase the stability when the sixth lens abuts against the fifth lens and the seventh lens through the spacer element.

[0095] In some embodiments of the present invention, the optical system satisfies: 0.70 < CT6 / (CT5 + CT7) ≤ 1.5; 0.40 < EP56 / (D6m - d6s) < 0.85; where CT6 is the central thickness of the sixth lens, CT5 is the central thickness of the fifth lens, CT7 is the central thickness of the seventh lens, EP56 is the distance between the fifth spacer element and the sixth spacer element along the optical axis direction, D6m is the outer diameter of the image side of the sixth spacer element, and d6s is the inner diameter of the object side of the sixth spacer element.

[0096] By constraining the relationship between the central thicknesses of the fifth lens, the sixth lens, and the seventh lens in the second lens barrel, and the relationship between the distance between the fifth spacer element and the sixth spacer element and the outer diameter of the image side and the inner diameter of the object side of the sixth spacer element, a reasonable distribution of the fifth lens, the sixth lens, the seventh lens, and the fifth spacer element and the sixth spacer element in the spatial layout within the second lens barrel can be achieved, and the abutting stability of each lens in the second lens barrel can be increased.

[0097] In some embodiments of the present invention, the optical system satisfies: 3.60 < R12 / CT6 < 7.95; 1.35 < D6m / d5s < 1.65; where R12 is the radius of curvature of the image side of the sixth lens, CT6 is the central thickness of the sixth lens, D6m is the outer diameter of the image side of the sixth spacer element, and d5s is the inner diameter of the object side of the fifth spacer element.

[0098] By constraining the ratio of the central thickness of the sixth lens to the radius of curvature of its image side and the ratio of the outer diameter of the image side of the sixth spacer element to the inner diameter of the object side of the fifth spacer element, while improving the surface forming process of the sixth lens, the refraction path of light in the sixth lens can be improved, and the inner and outer diameter intercepting edges of the spacer element can intercept the excess light, reducing the risk of stray light.

[0099] In some embodiments of the present invention, the optical system satisfies: 1.25 < d02m / d6s < 1.60; where d02m is the inner diameter of the image-side end face of the second lens barrel, and d6s is the inner diameter of the object-side face of the sixth spacer element.

[0100] By restricting the inner diameter of the image-side end face of the second lens barrel and the inner diameter of the object-side face of the sixth spacer element, the excessive light incident on the edge of the seventh lens and the excessive light emitted from the seventh lens are effectively intercepted, avoiding the primary stray light at the end of the second lens barrel and improving the imaging quality.

[0101] In a second aspect of the present application, an optical system is provided, including a first lens barrel, a second lens barrel, a first lens group, a second lens group, and a plurality of spacer elements. The first lens group is disposed within the first lens barrel, and the second lens group is disposed within the second lens barrel; the second lens group is disposed on the image side of the first lens group, and the second lens group is movable along the optical axis direction. The first lens group includes, in order from the object side to the image side along the optical axis, a first lens with a positive optical power, a second lens with an optical power, a third lens with an optical power, and a fourth lens with a positive optical power; the optical powers of the second lens and the third lens are of opposite signs; the second lens group includes, in order from the object side to the image side along the optical axis, a fifth lens with an optical power, a sixth lens with an optical power, and a seventh lens with a negative optical power; the optical powers of the fifth lens and the sixth lens are of opposite signs. The optical system satisfies: 4.20 mm < F1 / (N1 + N2) < 4.9 mm, 0.55 < EP01 / EP12 ≤ 1.10; where F1 is the effective focal length of the first lens group, N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, EP01 is the axial distance from the object-side end face of the first lens barrel to the object-side face of the first spacer element, and EP12 is the axial distance between the first spacer element and the second spacer element.

[0102] By reasonably setting the refractive indices of the first lens and the second lens, the risk of total reflection of light in the first lens and the second lens is reduced. Further, by reasonably setting the thickness of the non-light-transmitting regions of the first lens and the second lens to restrict the number of reflections of light in the non-light-transmitting regions, the risk of internal stray light in the first lens and the second lens is reduced.

[0103] The optical system according to the above-described embodiment of the present application may employ multiple lenses, such as the seven lenses described above. By reasonably distributing the optical powers, surface shapes of each lens, and the arrangement of each spacer element, etc., the span of each gear position where the lens and the lens barrel cooperate is relatively uniform, enhancing the ability of light convergence and improving the imaging quality of the optical system.

[0104] In some embodiments of the present invention, the lens material in the optical system provided by the present invention can be glass or plastic. When the lens material is plastic, production costs can be effectively reduced. Furthermore, when the lens material is glass, the low dispersion characteristic of glass itself can effectively correct the geometric chromatic aberration of the optical system.

[0105] When an aspherical lens is used, the shapes of each aspherical surface of the optical lens satisfy the following equation:

[0106]

[0107] In the above formula, z is the axial distance from the vertex to the surface at a position perpendicular to the optical axis at a height y; c represents the curvature at the vertex of the aspherical surface; k is the conic coefficient; A4, A6, A8, A 10 A 12 A 14 A 16 ...represent aspheric coefficients of the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth orders, respectively.

[0108] The present invention will be further described below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different; for specific differences, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.

[0109] It should be noted that "telephoto" refers to shooting a scene where the subject is at infinity, while "close-up" refers to shooting a scene where the subject is at a macro distance (e.g., 120mm). The telephoto position refers to the position of the lens group when shooting from a distance, and the close-up position refers to the position of the lens group when shooting close up.

[0110] Example 1

[0111] The following is for reference Figures 2A to 5C The optical systems 1001, 1002, and 1003 according to Embodiment 1 of this application are described. Figure 2A , Figure 2B and Figure 2C Schematic diagrams of optical systems 1001, 1002 and 1003 according to Embodiment 1 of this application are shown respectively. Figure 3The diagram shows the optical structures of optical systems 1001, 1002, and 1003 according to Embodiment 1 of this application in a far-viewing position and a close-viewing position. Since the size of the lenses and multiple spacers in the first and second lens barrels of the optical system, as well as the size of the first and second lens barrels, does not change in the far-viewing and close-viewing positions, the diagram only shows the relative positions of the optical structures in the far-viewing position.

[0112] like Figure 2A , Figure 2B and Figure 2C As shown, the structural schematic diagrams of optical systems 1001, 1002, and 1003 all include a first lens barrel P01, a first lens group E1 to E4, a second lens barrel P02, a second lens group E5 to E7, multiple spacer elements, and a first auxiliary spacer element P1b.

[0113] In Embodiment 1, the schematic diagrams of optical systems 1001, 1002, and 1003 use the same lens group. The first lens group includes, from the object side to the image side, a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has positive optical power, with its object side S1 being convex and its image side S2 being concave. The second lens E2 has negative optical power, with its object side S3 being convex and its image side S4 being concave. The third lens E3 has positive optical power, with its object side S5 being convex and its image side S6 being convex. The fourth lens E4 has positive optical power, with its object side S7 being concave and its image side S8 being convex. The second lens group, from the object side to the image side, includes, in sequence: a fifth lens E5 with negative optical power, a sixth lens E6 with positive optical power, and a seventh lens E7 with negative optical power. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being concave. The sixth lens E6 has positive optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The seventh lens E7 has negative optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged on the imaging surface S17. S15 and S16 are two surfaces of a protective glass or filter, OBJ (not shown in the figure) is the object surface, and STO is the aperture stop, which is located on the first lens E1.

[0114] Tables 1-1 and 1-2 list the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness / gap, refractive index of the material, Abbe number, conic coefficient, and the effective focal length, half of the maximum field of view, and FNO number of the optical system at the far-view and near-view positions. The units of radius of curvature, thickness, and effective focal length of the optical system are all millimeters (mm), and the unit of half of the maximum field of view (Semi-FOV) is degrees (°).

[0115] OBJ spherical endless D1 STO spherical endless -1.2000 S1 aspherical 7.3928 1.8517 1.487 70.42 0.0326 S2 aspherical 17.5464 2.2712 1.1108 S3 aspherical 10.4440 1.6594 1.639 23.39 0.0000 S4 aspherical 4.5365 0.4888 0.0000 S5 aspherical 5.8918 1.7060 1.544 56.11 0.0000 S6 aspherical -424.2392 0.2162 -86.3357 S7 aspherical -29.2113 1.6460 1.544 56.11 -1.7518 S8 aspherical -11.3164 D2 0.1599 S9 aspherical -27.7265 0.6136 1.544 56.11 1.0210 S10 aspherical 9.6068 0.3957 0.1377 S11 aspherical 7.4859 1.4314 1.661 20.37 0.0193 S12 aspherical 11.1059 1.4886 0.2148 S13 aspherical 5.6306 0.6051 1.544 56.11 -0.0895 S14 aspherical 4.3139 D3 -0.0137 S15 spherical endless 0.2100 1.517 64.17 S16 spherical endless 0.3900 S17 spherical endless

[0116] Table 1-1

[0117]

[0118]

[0119] Table 1-2

[0120] Table 2 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 A 30 .

[0121]

[0122] Table 2

[0123] like Figure 2A , Figure 2B and Figure 2C As shown, optical systems 1001, 1002 and 1003 each include four spacer elements and a first auxiliary spacer element P1b. The four spacer elements are the first spacer element P1, the second spacer element P2, the fifth spacer element P5 and the sixth spacer element P6.

[0124] The differences between optical systems 1001, 1002, and 1003 lie in the size of the spacer element, the non-light-transmitting area of ​​the lens, and the structural parameters of the lens barrel. The basic parameters of the spacer element and lens barrel of optical systems 1001, 1002, and 1003 in Embodiment 1 are shown in Table 7, where all parameters are in mm. As an example, optical systems 1001, 1002, and 1003 each have a first lens barrel P01 and a second lens barrel P02.

[0125] Figure 4A and Figure 5A The on-axis chromatic aberration curves of the optical system of Embodiment 1 are shown at the far-field and close-field positions, respectively, which indicate the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 4B and Figure 5BThe astigmatism curves of the optical system of Embodiment 1 at the far-field and near-field positions are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 4C and Figure 5C The distortion curves of the optical system of Embodiment 1 at the far-field and near-field positions are shown, representing the distortion magnitude values ​​corresponding to different image heights. According to... Figures 4A to 5C As can be seen, the optical system given in Example 1 can achieve good imaging quality.

[0126] Example 2

[0127] The following is for reference Figures 6A to 9C The optical systems 2001, 2002 and 2003 according to Embodiment 2 of this application are described. Figure 6A , Figure 6B and Figure 6C A schematic diagram of the structure of optical system 2001, optical system 2002 and optical system 2003 according to Embodiment 2 of this application is shown. Figure 7 The diagram shows the optical structure of optical systems 2001, 2002 and 2003 according to Embodiment 2 of this application at both the far-field and close-field positions.

[0128] like Figure 6A , Figure 6B and Figure 6C As shown, the structural schematic diagrams of optical systems 2001, 2002, and 2003 all include a first lens barrel P01, a first lens group E1 to E4, a second lens barrel P02, a second lens group E5 to E7, multiple spacer elements, and a first auxiliary spacer element P1b.

[0129] In Embodiment 2, the schematic diagrams of optical systems 2001, 2002, and 2003 use the same lens group. The first lens group, from the object side to the image side, includes: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has negative optical power, with its object-side surface S5 being convex. The image-side surface S6 is concave; the fourth lens E4 has positive optical power, its object-side surface S7 is convex, and its image-side surface S8 is convex. The second lens group, from the object side to the image side, includes: the fifth lens E5, the sixth lens E6, and the seventh lens E7. The fifth lens E5 has positive optical power, its object-side surface S9 is concave, and its image-side surface S10 is convex; the sixth lens E6 has negative optical power, its object-side surface S11 is convex, and its image-side surface S12 is concave; the seventh lens E7 has negative optical power, its object-side surface S13 is concave, and its image-side surface S14 is concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged on the imaging surface S17. S15 and S16 are two surfaces of a protective glass or filter, OBJ (not shown in the figure) is the object surface, and STO is the aperture stop, which is located on the object-side surface S3 of the second lens E2.

[0130] Tables 3-1 and 3-2 list the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness / gap, refractive index of the material, Abbe number, conic coefficient, and the effective focal length, half of the maximum field of view, and FNO number of the optical system at the far-view and near-view positions. The units of radius of curvature, thickness, and effective focal length of the optical system are all millimeters (mm), and the unit of half of the maximum field of view (Semi-FOV) is °.

[0131] OBJ spherical endless D1 S1 aspherical 14.0868 3.0000 1.589 61.16 -3.1245 S2 aspherical 16.1314 2.8145 -4.0733 S3(STO) aspherical 12.6770 2.4559 1.487 70.42 0.0000 S4 aspherical 29.5185 0.3049 1.3774 S5 aspherical 6.9942 1.7769 1.615 25.91 0.0000 S6 aspherical 3.5613 0.5668 -0.9996 S7 aspherical 7.1694 3.5000 1.544 56.11 0.0000 S8 aspherical -10.5323 D2 0.0000 S9 aspherical -16.7683 1.5290 1.661 20.37 0.0000 S10 aspherical -13.2034 0.1415 0.0000 S11 aspherical 31.1037 2.3376 1.544 56.11 0.0000 S12 aspherical 8.5022 1.6011 -0.1670 S13 aspherical -80.1000 1.7174 1.544 56.11 0.0000 S14 aspherical 26.0639 D3 23.3248 S15 spherical endless 0.2100 1.517 64.17 S16 spherical endless 1.2143 S17 spherical endless

[0132] Table 3-1

[0133] Distant shooting position 22.44 14.38 1.96 endless 0.5242 5.2847 Close-up position 15.97 15.21 1.8 120 4.8486 0.9603

[0134] Table 3-2

[0135] Table 4 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 A30 .

[0136]

[0137]

[0138] Table 4

[0139] like Figure 6A , Figure 6B and Figure 6C As shown, optical systems 2001, 2002 and 2003 each include five spacer elements and a first auxiliary spacer element P1b. The five spacer elements are the first spacer element P1, the second spacer element P2, the third spacer element P3, the fifth spacer element P5 and the sixth spacer element P6. The third spacer element P3 is disposed on the image side of the third lens E3 and is in contact with the image side of the third lens E3.

[0140] The differences between optical systems 2001, 2002, and 2003 lie in the size of the spacer element, the non-light-transmitting area of ​​the lens, and the structural parameters of the lens barrel. The basic parameters of the spacer element and lens barrel of optical systems 2001, 2002, and 2003 in Embodiment 2 are shown in Table 7. As an example, optical systems 2001, 2002, and 2003 each have a first lens barrel P01 and a second lens barrel P02.

[0141] Figure 8A and Figure 9A The on-axis chromatic aberration curves of the optical system of Embodiment 2 are shown at the far-field and close-field positions, respectively, which indicate the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 8B and Figure 9B The astigmatism curves of the optical system of Embodiment 2 at the far-field and near-field positions are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 8C and Figure 9C The distortion curves of the optical system of Embodiment 2 at the far-field and near-field positions are shown, representing the distortion magnitude values ​​corresponding to different image heights. According to... Figures 8A to 9C It can be seen that the optical system given in Example 2 can achieve good imaging quality.

[0142] Example 3

[0143] The following is for reference Figures 10A to 13C The optical systems 3001, 3002 and 3003 according to Embodiment 3 of this application are described. Figure 10A , Figure 10B and Figure 10CA schematic diagram of the structure of optical systems 3001, 3002 and 3003 according to Embodiment 3 of this application is shown. Figure 11 The diagram shows the structure of optical systems 3001, 3002 and 3003 according to Embodiment 3 of this application in the far-field and close-field positions.

[0144] like Figure 10A , Figure 10B and Figure 10C As shown, the structural schematic diagrams of optical systems 3001, 3002, and 3003 all include a first lens barrel P01, a first lens group E1 to E4, a second lens barrel P02, a second lens group E5 to E7, multiple spacer elements, and a first auxiliary spacer element P1b.

[0145] In Embodiment 3, the schematic diagrams of optical systems 3001, 3002, and 3003 use the same lens group. The lens group includes, from the object side to the image side, the following in sequence: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. The first lens E1 has positive optical power, its object side S1 is convex, and its image side S2 is concave. The second lens E2 has positive optical power, its object side S3 is convex, and its image side S4 is concave. The third lens E3 has negative optical power, its object side S5 is convex, and its image side S6 is concave. The fourth lens E4 has positive optical power, its object side S7 is convex, and its image side S8 is convex. The second lens group, from the object side to the image side, includes: a fifth lens E5, a sixth lens E6, and a seventh lens E7. The fifth lens E5 has negative optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens E6 has positive optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The seventh lens E7 has negative optical power, with its object-side surface S13 being convex and its image-side surface S14 being concave. Light from the object passes sequentially through surfaces S1 to S14 and is finally imaged on the imaging surface S17. S15 and S16 are two surfaces of a protective glass or filter, OBJ (not shown in the figure) is the object surface, and STO is the aperture stop, which is positioned between the third lens E3 and the fourth lens E4.

[0146] Tables 5-1 and 5-2 list the relevant parameters of each lens in the optical system of this embodiment, including: surface type, radius of curvature, thickness / gap, refractive index of the material, Abbe number, conic coefficient, and the effective focal length, half of the maximum field of view, and FNO number of the optical system at the far and near shooting positions. The units of radius of curvature, thickness / gap, and effective focal length of the optical system are all millimeters (mm), and the unit of half of the maximum field of view (Semi-FOV) is degrees (°).

[0147]

[0148]

[0149] Table 5-1

[0150] Distant shooting position 22.45 14.79 2.56 endless 1.1286 7.4642 Close-up position 16.82 14.42 2.56 120 3.4536 5.1389

[0151] Table 5-2

[0152] Table 6 lists the aspherical coefficients of each aspherical lens in the optical system of this embodiment, including: A4, A6, A8, A... 10 A 12 A 14 A 16 A 18 A 20 A 22 A 24 A 26 A 28 A 30 .

[0153]

[0154]

[0155] Table 6

[0156] like Figure 10A As shown in Figures B and C, optical systems 3001, 3002, and 3003 each include five spacer elements and a first auxiliary spacer element P1b. The five spacer elements are the first spacer element P1, the second spacer element P2, the third spacer element P3, the fifth spacer element P5, and the sixth spacer element P6. The third spacer element P3 is disposed on the image side of the third lens E3 and is in contact with the image side of the third lens E3.

[0157] The differences between optical systems 3001, 3002, and 3003 lie in the size of the spacer element, the non-light-transmitting area of ​​the lens, and the structural parameters of the lens barrel. The basic parameters of the spacer element and lens barrel of optical systems 3001, 3002, and 3003 in Embodiment 3 are shown in Table 7. As an example, optical systems 3001, 3002, and 3003 each have a first lens barrel P01 and a second lens barrel P02.

[0158] Figure 12A and Figure 13A The on-axis chromatic aberration curves of the optical system of Embodiment 3 are shown at the far-field and close-field positions, respectively, which indicate the deviation of the focal point of light of different wavelengths after passing through the lens. Figure 12B and Figure 13BThe astigmatism curves of the optical system of Embodiment 3 at the far-field and near-field positions are shown, representing the meridional image plane curvature and the sagittal image plane curvature. Figure 12C and Figure 13C The distortion curves of the optical system of Embodiment 3 at the far-field and near-field positions are shown, representing the distortion magnitude values ​​corresponding to different image heights. According to... Figures 12A to 13C As can be seen, the optical system given in Example 3 can achieve good imaging quality.

[0159] In summary, the optical parameters of the optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Embodiments 1 to 3 are shown in Table 7 below.

[0160]

[0161] Table 7

[0162] The basic parameters of the spacer elements and lens barrels of the optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002 and 3003 of Embodiments 1 to 3 are shown in Table 8 below.

[0163]

[0164] Table 8

[0165] The optical systems 1001, 1002, 1003, 2001, 2002, 2003, 3001, 3002, and 3003 of Examples 1 to 3 satisfy the relationships shown in Table 9.

[0166]

[0167] Table 9

[0168] 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 the invention 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 inventive concept. 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. An optical system comprising a first lens barrel, a second lens barrel, a first lens group, a second lens group, and a plurality of spacers, wherein the number of lens groups having optical power is two, the two lens groups being a first lens group having positive optical power and a second lens group having negative optical power, the first lens group being disposed within the first lens barrel, and the second lens group being disposed within the second lens barrel; characterized in that, The second lens group is positioned on the image side of the first lens group; The second lens group moves away from the first lens group along the optical axis, and the optical system moves from a far-shooting position to a close-shooting position; The first lens group includes, sequentially from the object side to the image side along the optical axis, a first lens with positive optical power, a second lens with optical power, a third lens with optical power, and a fourth lens with positive optical power, for a total of four lenses with optical power. The object side of the first lens is convex, and its image side is concave; the object side of the second lens is convex, and its image side is concave; the object side of the third lens is convex; and the image side of the fourth lens is convex. The second lens group includes, in sequence along the optical axis from the object side to the image side, a fifth lens with optical power, a sixth lens with optical power, and a seventh lens with negative optical power, for a total of three lenses with optical power; wherein, the object side of the sixth lens is convex and its image side is concave; the image side of the seventh lens is concave. The second lens has negative optical power; the third lens has positive optical power; the fifth lens has negative optical power; and the sixth lens has positive optical power. Alternatively, the second lens has positive optical power; the third lens has negative optical power; the fifth lens has positive optical power; and the sixth lens has negative optical power. Alternatively, the second lens has positive optical power; the third lens has negative optical power; the fifth lens has negative optical power; and the sixth lens has positive optical power. The plurality of spacer elements include: A first spacer element is disposed on the image side of the first lens and contacts the image side of the first lens; The second spacer element is disposed on the image side of the second lens and contacts the image side of the second lens; The optical system satisfies: 6.60 <FNOb / TAN(Semi-FOVb)<10.00; 2.95 <L1 / T12<5.35; 0.9 < (EP12 + CP1) / EP01 < 1.75; Wherein, T12 is the air gap between the first lens and the second lens on the optical axis, CP1 is the maximum thickness of the first spacer element along the optical axis, EP12 is the spacing distance between the first spacer element and the second spacer element along the optical axis, EP01 is the spacing distance between the object-side end face of the first lens barrel and the object-side face of the first spacer element along the optical axis, FNOb is the aperture number of the optical system at the close-up position, Semi-FOVb is half of the maximum field of view of the optical system at the close-up position, and L1 is the maximum height of the first lens barrel.

2. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.30 <fa / fb<1.45;1.70<L1 / L2≤2.05; Wherein, fa is the effective focal length of the optical system at the far shooting position, fb is the effective focal length of the optical system at the close shooting position, L1 is the maximum height of the first lens barrel, and L2 is the maximum height of the second lens barrel.

3. The optical system according to claim 1, characterized in that, The optical system satisfies: 2.15 <F1 / fa / tan(Semi-FOVa)≤2.60; Where F1 is the effective focal length of the first lens group, fa is the effective focal length of the optical system at the telephoto position, and Semi-FOVa is half of the maximum field of view of the optical system at the telephoto position.

4. The optical system according to claim 1, characterized in that, The optical system satisfies: 1.00 <F1 / L1<1.45;-2.70<F2 / L2<-2.00; Wherein, F1 is the effective focal length of the first lens group, L1 is the maximum height of the first lens barrel, F2 is the effective focal length of the second lens group, and L2 is the maximum height of the second lens barrel.

5. The optical system according to claim 1, characterized in that, The optical system meets the following requirement: 4.20mm <F1 / (N1+N2)<4.90mm;0.55<EP01 / EP12≤1.10; Wherein, F1 is the effective focal length of the first lens group, N1 is the refractive index of the first lens, N2 is the refractive index of the second lens, EP01 is the distance along the optical axis from the object-side end face of the first lens barrel to the object-side surface of the first spacer element, and EP12 is the distance along the optical axis between the first spacer element and the second spacer element.

6. The optical system according to claim 1, characterized in that, The optical system satisfies: -4.70 <F2 / (d02m-d02smin)<-3.60; Where F2 is the effective focal length of the second lens group, d02m is the inner diameter of the image-side end face of the second lens barrel, and d02smin is the minimum aperture of the object-side end of the second lens barrel.

7. The optical system according to claim 1, characterized in that, The plurality of spacers also includes a first auxiliary spacer element disposed on the image side of the first spacer element and in contact with the image side of the first spacer element; The optical system satisfies: 0.65 ≤ (EP12 - CP1b) / CT2 < 1.95; Wherein, EP12 is the distance between the first spacer element and the second spacer element along the optical axis, CP1b is the maximum thickness of the first auxiliary spacer element along the optical axis, and CT2 is the center thickness of the second lens.

8. The optical system according to any one of claims 1 to 7, characterized in that, The plurality of spacers also includes a fifth spacer element disposed on the image side of the fifth lens and in contact with the image side surface of the fifth lens, and a sixth spacer element disposed on the image side of the sixth lens and in contact with the image side surface of the sixth lens; The optical system includes: 0.25 <EP56 / L2<0.40; Wherein, EP56 is the distance between the fifth spacer element and the sixth spacer element along the optical axis, and L2 is the maximum height of the second lens barrel.

9. The optical system according to claim 8, characterized in that, The optical system satisfies: 0.70 <CT6 / (CT5+CT7)≤1.5;0.40<EP56 / (D6m-d6s)<0.85; Wherein, CT6 is the center thickness of the sixth lens, CT5 is the center thickness of the fifth lens, CT7 is the center thickness of the seventh lens, EP56 is the spacing distance between the fifth spacer element and the sixth spacer element along the optical axis, D6m is the outer diameter of the image side of the sixth spacer element, and d6s is the inner diameter of the object side of the sixth spacer element.

10. The optical system according to claim 8, characterized in that, The optical system satisfies: 3.60 <R12 / CT6<7.95;1.35<D6m / d5s<1.65; Wherein, R12 is the radius of curvature of the image side of the sixth lens, CT6 is the center thickness of the sixth lens, D6m is the outer diameter of the image side of the sixth spacer element, and d5s is the inner diameter of the object side of the fifth spacer element.

11. The optical system according to claim 8, characterized in that, The optical system satisfies: 1.25 <d02m / d6s<1.60; Wherein, d02m is the inner diameter of the image-side end face of the second lens tube, and d6s is the inner diameter of the object-side end face of the sixth spacer element.

Images