Optical system and camera module

Abstract

An optical system disclosed in an embodiment of the present invention includes: first to third lens groups arranged in a direction from an object to a sensor side along an optical axis and each including at least one lens, in which the first lens group and the third lens group have negative refractive power, the second lens group has positive refractive power, and the third lens group has positive refractive power; a position of the first lens group is fixed, each of the second and third lens groups moves along an optical axis according to an operation mode, a first lens closest to an object among lenses of the first lens group has a positive refractive power and has a convex sensor-side surface, an optical axis distance of the first lens group is DG1, an optical axis distance of the second lens group is DG2, and an optical axis distance of the third lens group is DG3. The mathematical formula: 0.5 lt can be met; dG1 / DG2lt; 2.

Description

Technical Field

[0001] The embodiments relate to an optical system for improving optical performance and a camera module including the optical system. Background Technology

[0002] Camera modules perform the function of capturing objects and storing them as images or videos, and are installed in a variety of applications. In particular, camera modules are manufactured in ultra-small sizes and are used in portable devices such as smartphones, tablet PCs, and laptops, as well as in drones and vehicles, thus providing a wide range of functions. For example, the optical system of a camera module may include an imaging lens that forms an image, and an image sensor that converts the formed image into an electrical signal. In this case, the camera module can perform an autofocus (AF) function that automatically adjusts the distance between the image sensor and the imaging lens to align the lens's focal length, and can perform zoom functions by increasing or decreasing the magnification of distant objects via a zoom lens. Additionally, the camera module employs image stabilization (IS) technology to compensate for or prevent image shake caused by camera movement due to unstable mounting or user movement.

[0003] The most crucial component for a camera module to acquire an image is the imaging lens that forms the image. Recently, there has been increasing focus on high resolution, and research is underway on optical systems incorporating multiple lenses to achieve this. For example, research is being conducted on using multiple imaging lenses with positive (+) or negative (-) refractive power to achieve high resolution. However, when multiple lenses are included, it becomes difficult to obtain excellent optical and aberration characteristics. Furthermore, when multiple lenses are included, the overall length, height, etc., may increase due to the thickness, distance, and size of the multiple lenses, thus increasing the overall size of the module incorporating multiple lenses.

[0004] Image sensor sizes are increasing to achieve high resolution and high-quality images. However, as image sensor sizes increase, the TTL (Total Track Length) of the optical system, which includes multiple lenses, also increases. This leads to an increase in the thickness of devices such as cameras and mobile terminals that include the optical system.

[0005] When an optical system includes multiple lenses, the position of at least one lens or a lens group including at least one lens can be controlled to perform functions such as zoom and autofocus (AF). However, when a lens or lens group performs this function, the amount of movement of the lens or lens group can increase exponentially. Therefore, the optical system may require a large amount of energy to move the lens or lens group, and the problem is that a large volume is required considering the amount of movement. Furthermore, the problem is that aberration characteristics deteriorate due to the movement of the lens or lens group. Therefore, the problem is that optical characteristics deteriorate at a certain magnification when performing zoom and autofocus (AF) functions. Therefore, a new optical system capable of solving the above problems is needed. Summary of the Invention

[0006] Technical issues

[0007] The embodiments provide optical systems with improved optical properties. The embodiments provide optical systems and camera modules capable of shooting at various magnifications. The embodiments provide optical systems and camera modules with improved aberration characteristics at various magnifications. The embodiments provide optical systems and camera modules that can be implemented in a small and compact manner.

[0008] Technical solution

[0009] According to an embodiment of the present invention, an optical system may include: a first lens group to a third lens group, each lens group including at least one lens and arranged along the optical axis from the object side to the sensor side, wherein the first lens group and the third lens group have negative optical power, the second lens group has positive optical power, the position of the first lens group is fixed, each of the second and third lens groups is movable along the optical axis according to an operating mode, the first lens in the first lens group closest to the object has positive optical power and has a convex surface on the sensor side, the distance of the first lens group along the optical axis is defined as DG1, the distance of the second lens group along the optical axis is defined as DG2, and satisfies the following formula: 0.5 <DG1 / DG2<2。

[0010] According to an embodiment of the present invention, the lenses in the first to third lens groups may be made of plastic, and the number of lenses with negative optical power in the first to third lens groups is greater than the number of lenses with positive optical power.

[0011] According to an embodiment of the present invention, the distance of the second lens group along the optical axis can be greater than the distance of each of the first lens group and the third lens group along the optical axis. The lens having the largest absolute focal length among the lenses of the first lens group to the third lens group can be disposed in the first lens group. The distance of the third lens group along the optical axis is defined as DG3, the distance along the optical axis from the object side surface of the lens closest to the object in the first lens group to the top surface of the image sensor is defined as TTL, and the following formula is satisfied: 2 < TTL / (DG2 + DG3) < 5.

[0012] According to an embodiment of the present invention, the distance along the optical axis between the lens closest to the image sensor in the third lens group and the image sensor can vary according to the operation mode, and the operation mode includes a wide angle mode, a middle focal length mode, and a telephoto mode.

[0013] According to an embodiment of the present invention, the distance along the optical axis between the object side surface of the lens closest to the object in the first lens group and the sensor side surface of the lens closest to the image sensor in the third lens group can vary according to the operation mode, and the distance between the first lens group and the second lens group and the distance between the second lens group and the third lens group are equal to or greater than 0.2 mm and equal to or less than 8 mm.

[0014] According to an embodiment of the present invention, the wide angle mode can be defined as Md1. In the wide angle mode, the distance between the first lens group and the second lens group can be DG12, the distance between the second lens group and the third lens group can be DG23, and the following formula can be satisfied: 1 < Md1×(DG12 / DG23) < 3. The telephoto mode can be defined as Md3. In the telephoto mode, the distance between the first lens group and the second lens group can be DG12, the distance between the second lens group and the third lens group can be DG23, and the following formula can be satisfied: 0 < Md3×(DG12 / DG23) < 0.5.

[0015] According to an embodiment of the present invention, the maximum distance between adjacent lenses according to the operation mode can be defined as Md_CG_Max, the minimum distance between adjacent lenses according to the operation mode can be defined as Md_CG_Min, and the following formula can be satisfied: 4 < Md_CG_Max / Md_CG_Min < 7.

[0016] According to an embodiment of the present invention, the number of lenses in the first lens group can be greater than the number of lenses in the second lens group, and the absolute value of the focal length of the first lens group can exceed twice the absolute value of the focal length of the second lens group. The effective focal length in the wide angle mode can be defined as FMd1, the focal length of the first lens can be defined as F1, and the following formula can be satisfied: 2 < |F1 / FMd1| < 7.

[0017] According to an embodiment of the present invention, the effective focal length in telephoto mode can be defined as FMd3, and can satisfy the following formula: 0 < |F1 / FMd3| < 1. The field of view in wide-angle mode can be defined as FOV1, the field of view in medium telephoto mode can be defined as FOV2, and the field of view in telephoto mode can be defined as FOV3, and can satisfy the following formula: 8° <FOV3<FOV2<FOV1<45°。

[0018] An optical system according to an embodiment of the present invention may include: a first lens group including a first lens to a third lens; a second lens group including a fourth lens and a fifth lens; and a third lens group including a sixth lens to an eighth lens, wherein the first lens group to the third lens group are arranged sequentially along the optical axis from the object side to the sensor side, the first lens has positive refractive power and has convex surfaces on both the object side and the sensor side, the third lens has negative refractive power and has a concave object-side surface and a convex sensor-side surface, the fourth lens has positive refractive power and has a biconvex shape, the eighth lens has negative refractive power, the second lens group and the third lens group are movable along the optical axis, the distance between the eighth lens and the image sensor is variable according to the operating mode, the number of lenses with a refractive index greater than 1.60 among the first lens to the eighth lens is greater than the number of lenses with a refractive index less than 1.60, the refractive index of the first lens is defined as Nd1, and satisfies the following formula: 1.65 <Nd1。

[0019] According to embodiments of the present invention, the first and third lens groups may have negative refractive power, and the second and fourth lenses have refractive power with opposite signs. The fourth and eighth lenses may each have a refractive index less than 1.6. Among the object-side and sensor-side surfaces of the first to eighth lenses, the third lens may have the largest absolute radius of curvature on its object-side surface.

[0020] According to an embodiment of the present invention, the effective diameter of the first lens can be the largest among the first to eighth lenses; the maximum length of the first lens in a first direction perpendicular to the optical axis can be different from the maximum length of the first lens in a second direction; the maximum effective size of the lens surface with the largest diameter among the first to eighth lenses can be defined as CA_Max; and half the diagonal length of the image sensor can be defined as ImgH, satisfying the following formula: 1 <CA_Max / ImgH<3。

[0021] A camera module according to an embodiment of the present invention may include: an image sensor; an optical system; and a driving member configured to move at least one of a plurality of lens groups in the optical system along an optical axis, the optical system including the aforementioned optical system, and the driving member configured to move the position of each of a second lens group and a third lens group on the optical axis.

[0022] The effects of the invention

[0023] The optical system and camera module according to the embodiments have various magnifications and can exhibit excellent optical characteristics when providing various magnifications. Specifically, the embodiments can have various magnifications by controlling the movement distance of each of the moving lens groups and can provide autofocus (AF) functionality for the subject. The optical system and camera module according to the embodiments can correct the aberration characteristics of multiple lens groups or complement each other aberration characteristics that change due to movement. Therefore, the optical system according to the embodiments can minimize or prevent changes in chromatic aberration and aberration characteristics that occur when the magnification changes.

[0024] The optical system and camera module according to the embodiments can control the effective focal length (EFL) by moving only some of the multiple lens groups, and can minimize the movement distance of the moving lens groups. Therefore, the optical system can reduce the movement distance of the moving lens groups according to changes in the operating mode, and can minimize the power consumption required when the lens groups move. The optical system may have at least one lens included in a fixed group, and the moving group has a non-circular shape. Therefore, the optical system can reduce its height while maintaining optical performance, and can ensure sufficient structural space for the lens groups arranged among the multiple lens groups.

[0025] The optical system and camera module according to the embodiment can adjust the magnification by moving lens groups other than the first lens group adjacent to the object among a plurality of lens groups. Therefore, even when the lens groups move according to changes in magnification, the optical system can maintain a constant TTL value. Thus, the optical system and the camera module including the optical system can be provided to have a thinner structure. Attached Figure Description

[0026] Figure 1 This is a structural diagram of an optical system and a camera module having the optical system according to an embodiment of the present invention.

[0027] Figure 2 yes Figure 1 An example of the change in the first mode of an optical system.

[0028] Figure 3 yes Figure 1 and Figure 2 An example of the variation of the third mode in an optical system.

[0029] Figure 4 Is Figure 1 The optical system has a mirror configuration.

[0030] Figure 5This is a table of lens data for an optical system according to an embodiment of the present invention.

[0031] Figure 6 This is a table showing the aspherical coefficients of lenses in an optical system according to an embodiment of the present invention.

[0032] Figure 7 This is a graph showing the relative illumination of the positions according to wide-angle mode, medium-telephoto mode and telephoto mode according to an embodiment of the present invention.

[0033] Figure 8 This is a diagram of the diffraction MTF in an optical system of the first mode (wide-angle mode) according to an embodiment of the present invention.

[0034] Figure 9 This is a diagram of the diffraction MTF in the second mode (central focal mode) optical system according to an embodiment of the present invention.

[0035] Figure 10 This is a graph of the diffraction MTF in the third mode (telephoto mode) optical system according to an embodiment of the present invention.

[0036] Figure 11 This is a graph illustrating the aberration characteristics in an optical system of a first mode according to an embodiment of the present invention.

[0037] Figure 12 This is a graph illustrating the aberration characteristics in a second-mode optical system according to an embodiment of the present invention.

[0038] Figure 13 This is a graph illustrating the aberration characteristics in a third mode optical system according to an embodiment of the present invention.

[0039] Figure 14 This is a diagram illustrating a camera module according to an embodiment of the present invention applied to a mobile terminal. Detailed Implementation

[0040] Preferred embodiments of the invention will be described in detail below with reference to the accompanying drawings. However, the inventive concept is not limited to some of the described embodiments, but can be implemented in various different forms, and one or more components in the embodiments can be selectively combined or substituted within the scope of the inventive concept. Furthermore, unless explicitly and specifically defined and described, the terminology (including technical and scientific terms) used in the embodiments of the invention is to be interpreted as having a meaning commonly understood by one of ordinary skill in the art to which this invention pertains, and commonly used terms (such as terms defined in dictionaries) may be interpreted considering the contextual meaning of the relevant art. The terminology used in the embodiments of the invention is for describing embodiments and is not intended to limit the invention.

[0041] In this specification, unless specifically stated in the phrase, the singular may also include the plural, and when described as “at least one (or more than one) of A and (and) B, C,” it may include one or more of all combinations that can be combined with A, B, and C. Furthermore, when describing components of embodiments of the invention, terms such as first, second, A, B, (a), (b), etc., may be used. These terms are intended only to distinguish a component from other components and are not limited by the nature, order, or sequence of the components. Moreover, when a component is described as 'connected,' 'coupled,' or 'joined' to another component, it may include not only cases where the component is directly connected, coupled, or joined to another component, but also cases where the component is 'connected,' 'coupled,' or 'joined' through other components between the component and the other component. When described in the specification as each component being formed or arranged “above or below,” “above” or “below” includes not only cases where two components are in direct contact with each other, but also cases where one or more other components are formed or arranged between the two components. Additionally, when expressed as "above or below", it can include not only the upward direction based on a component but also the downward direction based on a component.

[0042] In the specification, "convexity of the lens surface" can mean that the lens surface in the region corresponding to the optical axis has a convex shape based on the optical axis, and "recession of the lens surface" can mean that the lens surface in the region corresponding to the optical axis has a concave shape. Additionally, "object-side surface" can mean the surface of the lens facing the object side based on the optical axis, and "sensor-side surface" can mean the surface of the lens facing the imaging surface (image sensor) based on the optical axis. Furthermore, "center thickness of the lens" can mean the thickness of the lens in the optical axis direction. Additionally, "vertical direction" can mean the direction perpendicular to the optical axis, and "end of the lens or lens surface" can mean the end of the effective area of ​​the lens through which incident light passes. Furthermore, depending on the measurement method, the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm.

[0043] Figure 1 This is a structural diagram of a first mode of a camera module or optical system according to an embodiment of the present invention. Figure 2 From Figure 1 An example of the change from the first mode to the second mode in an optical system. Figure 3 From Figure 1 and Figure 2 Examples of changes in optical systems to the third mode, Figure 4 Is Figure 1 The optical system has a mirror configuration. Figure 5 This is a table of lens data for an optical system according to an embodiment of the present invention. Figure 6This is a table showing the aspherical coefficients of lenses in an optical system according to an embodiment of the present invention. Figure 7 This is a graph showing the relative illumination of the camera module according to the positions in wide-angle mode, medium telephoto mode, and telephoto mode according to an embodiment of the present invention. Figure 8 This is a graph of the diffraction MTF in the first mode (wide-angle mode) optical system according to an embodiment of the present invention. Figure 8 This is a graph of the diffraction MTF in the second mode (mid-focus mode) optical system according to an embodiment of the present invention. Figure 10 This is a graph illustrating the diffraction MTF in an optical system of the third mode (telephoto mode) according to an embodiment of the present invention. Figure 11 This is a graph illustrating the aberration characteristics in an optical system of a first mode according to an embodiment of the present invention. Figure 12 This is a graph illustrating the aberration characteristics in a second-mode optical system according to an embodiment of the present invention, and Figure 13 This is a graph illustrating the aberration characteristics in a third mode optical system according to an embodiment of the present invention.

[0044] refer to Figures 1 to 6 The optical system 1000 according to an embodiment may include a plurality of lens groups G1, G2, and G3. Specifically, the plurality of lens groups G1, G2, and G3 may have at least two lens groups movable in the direction of the optical axis OA and at least one lens group fixed in position. The plurality of lens groups G1, G2, and G3 may include a lens group fixed on the object side and a plurality of movable lens groups movable on the sensor side. The plurality of movable lens groups may include an object-side lens group and a sensor-side lens group.

[0045] The lens group fixed to the object side can be defined as the first lens group G1, the object-side movable lens group can be defined as the second lens group G2, and the sensor-side movable lens group can be defined as the third lens group G3. The second lens group G2 can be arranged between the first lens group G1 and the third lens group G3. The first lens group G1 refracts the incident light toward the second lens group G2, the second lens group G2 moves along the optical axis OA and changes the zoom ratio (focal length), and the third lens group G3 moves along the optical axis OA and can adjust the focal position on the image plane of the image sensor 300.

[0046] The optical system 1000 may include a first lens group G1, a second lens group G2, and a third lens group G3 arranged sequentially along the optical axis OA from the object toward the sensor. The optical system 1000 may include an image sensor 300 on the sensor side of the third lens group G3. The first lens group G1 may include the lens closest to the object side, and the third lens group G3 may include the lens closest to the sensor side. Each of the first to third lens groups G1, G2, and G3 may have positive (+) or negative (-) refractive power. For example, a lens group with positive refractive power may be smaller than a lens group with negative refractive power.

[0047] The first lens group G1 can have a refractive force with the opposite sign to that of the second lens group G2. For example, the first lens group G1 can have a negative (-) refractive force, and the second lens group G2 can have a positive (+) refractive force. The second lens group G2 can also have a refractive force with the opposite sign to that of the third lens group G3. For example, the second lens group G2 can have a positive (+) refractive force, and the third lens group G3 can have a negative (-) refractive force.

[0048] The absolute value of the focal length of the first lens group G1 can be greater than the absolute values ​​of the focal lengths of the second lens group G2 and the third lens group G3. For example, the absolute value of the focal length of the first lens group G1 can be more than twice the focal length of the second lens group G2. Therefore, the first lens group G1 can disperse the incident light. The absolute value of the focal length of the second lens group G2 can be less than the absolute value of the focal length of the third lens group G3. The absolute value of the focal length of the third lens group G3 can be less than the absolute value of the focal length of the first lens group G1. The optical power of the first lens group G1 and the third lens group G3 can be negative, and the optical power of the second lens group G2 can be positive. Optical power is the reciprocal of the focal length value.

[0049] The number of lenses in the first lens group G1 can be greater than the number of lenses in the second lens group G2. The number of lenses in the second lens group G2 can be equal to or less than the number of lenses in the third lens group G3. The number of lenses in the first lens group G1 can include at least three lenses for adjusting the amount of incident light, refractive power, and chromatic aberration. The third lens group G3 can include at least two or three lenses.

[0050] The number of lenses in the first to third lens groups G1, G2, and G3 can be two or more. At least one of the first lens group G1 and the third lens group G3 can include three or more lenses. As another example, the optical system may also include at least one lens positioned between the third lens group G3 and the image sensor 300. Therefore, the optical system 1000 can include seven or more lenses and ten or fewer lenses.

[0051] Because the first and second lens groups G1 and G2 have refractive forces with opposite signs (+, -), aberrations can be corrected. And because the second and third lens groups G2 and G3 have refractive forces with opposite signs (+, -), aberrations can also be corrected.

[0052] The absolute value of the focal length of each of the first to third lens groups G1, G2, and G3 can also decrease in the order of the first lens group G1, the third lens group G3, and the second lens group G2. The first lens group G1 is fixed in position, and the second and third lens groups G2 and G3 are moved M1 and M2 in the direction of the optical axis OA, respectively. The optical system 1000 can provide various magnifications by moving at least two lens groups. The first to third lens groups G1, G2, and G3 will be described in more detail below. The first lens group G1 may include at least two lenses with opposite signs of refractive power, and the at least two lenses may have refractive power of the same sign. For example, the first lens group G1 may include three lenses. The number of lenses with negative refractive power in the first lens group G1 may be greater than the number of lenses with positive refractive power.

[0053] The first lens group G1 may include multiple lenses, and these lenses may have a predetermined interval along the optical axis OA. Specifically, the center interval between the multiple lenses 101, 102, and 103 included in the first lens group G1 may be a fixed interval depending on the operating mode described below. For example, the center interval between adjacent lenses 101, 102, and 103 in the first lens group G1 may also be a constant interval, not varying according to the operating mode. Here, the center interval between lenses may refer to the optical axis interval between adjacent lenses. The second lens group G2 may include multiple lenses, and may include lenses 104 and 105 with refractive powers of opposite signs. The multiple lenses 104 and 105 included in the second lens group G2 may have a predetermined interval. Specifically, the center interval between adjacent lenses 104 and 105 may be a fixed interval depending on the operating mode described below.

[0054] The third lens group G3 may include multiple lenses, and may include two or more lenses with opposite refractive powers. The number of lenses included in the third lens group G3 may be greater than the number of lenses with positive refractive powers. The number of lenses included in the third lens group G3 may be at least one more than the number of lenses included in the second lens group G2. The number of lenses included in the third lens group G3 may be equal to the number of lenses included in the first lens group G1. For example, the third lens group G3 may include three lenses. The multiple lenses 106, 107, and 108 included in the third lens group G3 may have a predetermined interval. In detail, the center interval between the multiple lenses 106, 107, and 108 included in the third lens group G3 may be constant, even if the operating mode described later changes. For example, the center interval between adjacent lenses 106, 107, and 108 may be constant and does not change according to the operating mode. The last lens included in the third lens group G3 has a predetermined interval with the image sensor 220 and / or the filter 500, and the interval may vary according to the operating mode.

[0055] The optical system 1000 may include first lenses to eighth lenses 101, 102, 103, 104, 105, 106, 107, and 108. The first lens group G1 may include first lenses to third lenses 101, 102, and 103, and the second lens group G2 may include a fourth lens 104 and a fifth lens 105. Additionally, the third lens group G3 may include sixth lenses to eighth lenses 106, 107, and 108. The first lenses 101 to eighth lenses 108 and the image sensor 300 may be arranged sequentially along the optical axis OA of the optical system 1000.

[0056] At least one lens in the first lens group G1 may have different effective lengths in a first direction (X) and a second direction (Y) orthogonal to the optical axis OA. The lens in the first lens group G1 with different effective lengths in the first and second directions (X, Y) may be a non-circular lens; for example, the effective length in the second direction (Y) may be less than the effective length in the first direction (X). The effective length of the object-side surface of one or more of the first to third lenses 101, 102, and 103 in the second direction (Y) may be less than the effective length in the first direction (X). At least one lens in the second lens group G2 may have different effective lengths in a first direction (X) and a second direction (Y) orthogonal to the optical axis OA. The lens in the second lens group G2 with different effective lengths in the first and second directions (X, Y) may be a non-circular lens; for example, the effective length in the second direction (Y) may be less than the effective length in the first direction (X). The effective length of the object-side surface of one or both of the fourth lens 104 and the fifth lens 105 in the second direction (Y) may be less than the effective length in the first direction (X).

[0057] At least one lens in the third lens group G3 may have different effective lengths in a first direction (X) and a second direction (Y) perpendicular to the optical axis OA. The lens in the first lens group G1, which has different effective lengths in the first and second directions (X, Y), may be a non-circular lens; for example, the effective length in the second direction (Y) may be less than the effective length in the first direction (X). Specifically, among the lenses in the lens unit 100, the first lens 101, having the largest effective length, may have an effective length in the first direction (X) that is longer than its effective length in the second direction (Y). The second lens 102 may have an effective length in the first direction (X) that is longer than its effective length in the second direction (Y). The fourth lens 104 may have an effective length in the first direction (X) that is longer than its effective length in the second direction (Y).

[0058] The optical system 1000 according to the embodiment has improved assemblability due to the use of non-circular lenses and can have a mechanically stable form. Furthermore, the optical system 1000 can significantly reduce the movement distances DG12, DG23, and DG4 of the moving lens groups G2 and G3 and provide various magnifications. Additionally, since the lenses having a large effective length in the second direction (Y) are configured with a shape cut off on both sides of the second direction (Y), the height or thickness of the optical system 1000 and the camera module in the second direction (Y) can be reduced. Therefore, the increase in the thickness of the device having a thin optical system 1000 and camera module can be suppressed.

[0059] Each lens in the lens unit 100 may include an effective region and an ineffective region. The effective region is the area of ​​the effective diameter and may be the region through which light incident on each of the first lens 101 to the eighth lens 108 passes. The effective region may be the region in which incident light is refracted to achieve optical properties. The ineffective region may be arranged around the effective region. The ineffective region may be a region where light is not incident. In other words, the ineffective region may be a region unrelated to optical properties. Additionally, the ineffective region may be a region fixed to a lens barrel (not shown) that houses the lens.

[0060] Image sensor 300 can detect light. Image sensor 300 can detect light passing sequentially through lens unit 100 (e.g., first lens 101 to eighth lens 108). Image sensor 300 may include CCD (charge-coupled device) or CMOS (complementary metal-oxide-semiconductor). Optical system 1000 may also include filter 500. Filter 500 may be disposed between lens unit 100 and image sensor 300. Filter 500 may be disposed between image sensor 300 and third lens group G3. For example, filter 500 may be placed between eighth lens 108 and image sensor 300. Filter 500 may include at least one of infrared filter and cover glass. Filter 500 allows light of a set wavelength band to pass through and filters light of different wavelength bands. When filter 500 includes infrared filter, it can block radiant heat emitted from external light from being transferred to image sensor 300. Filter 500 can transmit visible light and reflect infrared light.

[0061] Optical system 1000 may include an aperture stop (not shown). The aperture stop can adjust the amount of light incident on optical system 1000. The aperture stop may be placed around the object-side surface of fourth lens 104. The aforementioned aperture stop may be arranged between two lenses selected from first lens 101 to eighth lens 108. For example, the aperture stop may be arranged on the periphery between third lens 103 and fourth lens 104. The aperture stop may be arranged on the periphery of the sensor-side surface of third lens 103 or the periphery of the object-side surface of fourth lens 104. Alternatively, at least one of the first lens 101 to eighth lens 108 may be used as an aperture stop. For example, the outer portion of the object-side surface or sensor-side surface of one of the lenses selected from first lens 101 to eighth lens 108 may be used as an aperture stop for controlling the amount of light. For example, at least one lens surface of the sensor-side surface of third lens 103 and the object-side surface of fourth lens 104 may be used as an aperture stop.

[0062] The object-side and sensor-side surfaces of the first lens 101 to the eighth lens 108 may be aspherical. The first lens 101 to the eighth lens 108 may be made of plastic material. Alternatively, at least one of the first to third lenses 101, 102 and 103 may be made of glass material.

[0063] like Figure 4 As shown, the optical system 1000 may further include a light path changing member 400. The light path changing member 400 can reflect light incident from the outside and change the light path from a second path OA2 to a first path OA1. The light path changing member 400 may include a reflector or a prism. For example, the light path changing member 400 may include a right-angle prism. When the light path changing member 400 includes a right-angle prism, the light path changing member 400 can reflect the second path OA2 of the incident light at a 90-degree angle to change the first path OA1 of the light. The first path OA1 may be in the direction of the optical axis of the optical system. The light path changing member 400 may be arranged closer to the object side than multiple lenses. That is, when the optical system 1000 includes the optical path changing member 400, the optical path changing member 300, the first lens 101, the second lens 102, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, the seventh lens 107, the eighth lens 108, the filter 500, and the image sensor 300 can be arranged in this order from the object side toward the sensor side. The aforementioned optical path changing member 400 can change the path of light incident from the outside to a set direction. For example, the optical path changing member 400 can change the second path OA2 of the light incident on the optical path changing member 400 in the second direction (Y) to the first path OA1 in the third direction (Z), where the third direction Z is the arrangement direction of the multiple lenses. When the optical system 1000 includes the optical path changing member 400, the optical system can be applied to a folding camera, thereby reducing the thickness of the camera. In detail, when the optical system 1000 includes the optical path changing member 400, light incident in a direction (Y) perpendicular to the surface of the device to which the optical system 1000 is applied can be changed to a direction (Z) parallel to the surface of the device. Therefore, the optical system 1000 including multiple lenses can have a thinner thickness within the device, thereby reducing the height of the device.

[0064] If the optical system 1000 does not include the optical path changing member, the multiple lenses can be arranged to extend in a direction (Y) perpendicular to the surface of the device. Therefore, the optical system 1000 including the multiple lenses has a relatively high height in the direction perpendicular to the surface of the device (first direction), making it difficult to form the optical system 1000 and the device including the optical system thin. However, if the optical system 1000 includes the optical path changing member 400, the multiple lenses can be arranged to extend in a direction parallel to the surface of the device (Z). That is, the optical system 1000 is arranged such that the optical axis OA is parallel to the surface of the device, and it can be applied to a folding camera. Therefore, the optical system 1000 including the lens unit 100 can have a low height in the direction perpendicular to the surface of the device. Therefore, the camera including the optical system 1000 can have a thin thickness within the device, and the thickness of the device can also be reduced. As another example, the optical path changing member can be arranged between two lenses of the lens unit 100, or it can be further disposed between the last lens adjacent to the image sensor 300 and the image sensor 300. As another example, multiple optical path changing members can be provided. In detail, multiple optical path changing components can be arranged between the object and the image sensor 300. For example, the multiple optical path changing components may include a first optical path changing component arranged closer to the object side than multiple lenses, and a second optical path changing component arranged between the last lens and the image sensor 300. Therefore, the optical system 1000 can have various shapes and heights depending on the camera to which it is applied, and can have improved optical performance.

[0065] refer to Figures 1 to 3Among the multiple lenses, the first lens 101 can be arranged closest to the object, and the eighth lens 108 can be arranged closest to the image sensor 300. For ease of explanation, the center thickness of each of the first lens 101 to the eighth lens 108 is CT1 to CT8, the edge thickness is ET1 to ET8, the Abbe number is Vd1 to Vd8, the refractive index is Nd1 to Nd8, the average effective length is CA1 to CA8, and the focal length can be defined as F1 to F8. The first lens 101 can have a positive (+) refractive power at the optical axis OA. The first lens 101 can include plastic or glass material, and can be, for example, plastic material. The first lens 101 can include a first surface S1 on the object side and a second surface S2 on the sensor side. The first surface S1 can have a convex shape on the optical axis OA, and the second surface S2 can also have a convex shape on the optical axis OA. That is, both surfaces of the first lens 101 can have convex shapes on the optical axis OA. Alternatively, the first surface S1 of the first lens 101 may have a convex shape on the optical axis, and the second surface S2 may have a concave shape on the optical axis OA. Alternatively, the first lens 101 may have a meniscus shape convex on the sensor side. At least one of the first surface S1 and the second surface S2 may be aspherical. For example, both the first surface S1 and the second surface S2 may be aspherical. The aspherical coefficients of the first surface S1 and the second surface S2 may be determined by... Figure 6 L1S1 and L1S2 are represented in the text.

[0066] The effective length of the first lens 101 can be the largest among all lenses, meaning the first lens 101 can have the maximum effective length. Specifically, the effective length of the first surface S1 of the first lens 101 in the second direction (Y) can be the largest among all lenses. The average effective length of the first surface S1 and the second surface S2 of the first lens 101 in the second direction (Y) can be greater than the average effective length of the object-side surfaces and sensor-side surfaces of the second lens 102 to the eighth lens 108. Therefore, the first lens 101 can improve optical aberrations or control incident light. The first surface S1 and the second surface S2 can be configured without a critical point at the end of the effective region from the optical axis.

[0067] The second lens 102 may have positive (+) or negative (-) refractive power on the optical axis OA, for example, it may have negative (-) refractive power. The second lens 102 may comprise a plastic or glass material, for example, it may be made of a plastic material. The second lens 102 may include a third surface S3 defined as an object-side surface and a fourth surface S4 defined as a sensor-side surface. The third surface S3 may have a concave shape on the optical axis OA, and the fourth surface S4 may have a convex shape on the optical axis OA. The second lens 102 may have a meniscus shape convex toward the sensor on the optical axis OA. Alternatively, the third surface S3 may have a convex shape on the optical axis OA, and the fourth surface S4 may have a concave shape on the optical axis OA. Alternatively, the third surface S3 may have a concave shape on the optical axis OA, and the fourth surface S4 may have a concave shape on the optical axis OA. Alternatively, the third surface S3 may have a convex shape on the optical axis OA, and the fourth surface S4 may have a convex shape on the optical axis OA. At least one of the third surface S3 and the fourth surface S4 of the second lens 102 may be aspherical. For example, both the third surface S3 and the fourth surface S4 may be aspherical. The aspherical coefficients of the third surface S3 and the fourth surface S4 can be determined by... Figure 6 L2S1 and L2S2 are represented in the figure. The third surface S3 and the fourth surface S4 can be configured to have no critical point at the end of the effective region from the optical axis, or at least one of the third surface S3 and the fourth surface S4 can have a critical point.

[0068] The third lens 103 may have a refractive power on the optical axis OA with the same sign as the refractive power of the second lens 102. That is, the third lens 103 may have a negative (-) refractive power. The third lens 103 may comprise a plastic or glass material, and may be, for example, a plastic material. The third lens 103 may comprise a fifth surface S5 defined as an object-side surface and a sixth surface S6 defined as a sensor-side surface. The fifth surface S5 may have a concave shape on the optical axis OA, and the sixth surface S6 may have a concave shape on the optical axis OA. Alternatively, the fifth surface S5 may have a convex shape on the optical axis OA, and the sixth surface S6 may have a concave shape. Alternatively, the fifth surface S5 may have a concave shape on the optical axis OA, and the sixth surface S6 may have a convex shape. At least one of the fifth surface S5 and the sixth surface S6 of the third lens 103 may be aspherical. For example, both the fifth surface S5 and the sixth surface S6 may be aspherical. The aspheric coefficients of the fifth surface S5 and the sixth surface S6 may be determined by... Figure 6 L3S1 and L3S2 are represented in the diagram. The fifth surface S5 and the sixth surface S6 can be configured to have no critical point at the end of the effective region from the optical axis. As another example, at least one of the fifth surface S5 and the sixth surface S6 can have a critical point at the end of the effective region from the optical axis.

[0069] The second lens 102 and the third lens 103 can compensate for chromatic aberration occurring in the first lens 101. The refractive index of the first lens 101 can be greater than 1.6. The first lens 101 can be the lens with the highest refractive index among the lenses. The radius of curvature of the sixth surface S6 of the third lens 103 can be the smallest among the object-side and sensor-side radii of curvature of each lens 101, 102, and 103 in the first lens group G1. The absolute value of the radius of curvature of the fifth surface S5 of the third lens 103 can be the largest among the object-side and sensor-side radii of curvature of each lens 101, 102, and 103 in the first lens group G1. Therefore, since the first lens group G1 controls the dispersion of light supplied to the second lens group G2, the lens size of the second lens group G2 can be reduced. The variable dimension of the center distance DG12 between the first and second lens groups G1 and G2 can be set according to the operating mode via the radius of curvature of the sixth surface S6 of the third lens 103.

[0070] The fourth lens 104 may have a positive (+) refractive power along the optical axis OA. The fourth lens 104 may comprise a plastic or glass material, and may be, for example, a plastic material with a refractive index less than 1.6. The fourth lens 104 may comprise a seventh surface S7 defined as the object-side surface and an eighth surface S8 defined as the sensor-side surface. The seventh surface S7 may have a convex shape relative to the optical axis OA, and the eighth surface S8 may have a convex shape relative to the optical axis OA. That is, both surfaces of the fourth lens 104 may have convex shapes relative to the optical axis OA. Alternatively, the seventh surface S7 may be convex relative to the optical axis OA, and the eighth surface S8 may be concave relative to the optical axis OA. That is, the fourth lens 104 may have a meniscus shape convex toward the object relative to the optical axis OA. At least one of the seventh surface S7 and the eighth surface S8 of the fourth lens 104 may be aspherical. For example, both the seventh surface S7 and the eighth surface S8 may be aspherical. The aspheric coefficients of the seventh surface S7 and the eighth surface S8 may be determined by… Figure 6 L4S1 and L4S2 are represented in the diagram. The seventh surface S7 and the eighth surface S8 can be configured to have no critical point at the end of the effective region from the optical axis.

[0071] The fifth lens 105 may have a positive (+) or negative (-) refractive power on the optical axis OA. The fifth lens 105 may have a negative refractive power on the optical axis OA, with the opposite sign to the refractive power of the fourth lens 104 on the optical axis OA. The fifth lens 105 may comprise a plastic or glass material, and may be, for example, a plastic material. The fifth lens 105 may comprise a ninth surface S9 defined as the object-side surface and a tenth surface S10 defined as the sensor-side surface. The ninth surface S9 may have a concave shape on the optical axis OA, and the tenth surface S10 may have a convex shape on the optical axis OA. That is, the fifth lens 105 may have a meniscus shape convex toward the sensor on the optical axis OA. At least one of the ninth surface S9 and the tenth surface S10 may be aspherical. For example, both the ninth surface S9 and the tenth surface S10 may be aspherical. The aspheric coefficients of the ninth surface S9 and the tenth surface S10 may be expressed as... Figure 6 L5S1 and L5S2 in the fifth lens 105. The ninth surface S9 and the tenth surface S10 of the fifth lens 105 can be set to have no critical point from the end of the optical axis to the effective area.

[0072] As another example, the ninth surface S9 of the fifth lens 105 can have a convex shape on the optical axis OA, and the tenth surface S10 can also have a convex shape on the optical axis OA. That is, both surfaces of the fifth lens 10 can have convex shapes on the optical axis OA. The difference is that the ninth surface S9 can have a concave shape on the optical axis OA, and the tenth surface S10 can have a concave shape on the optical axis OA.

[0073] The fourth lens 104 has convex shapes on both sides, and the center thickness CT4 of the fourth lens 104 can be thicker than the edge thickness ET4, for example, it can be at least twice the edge thickness. Therefore, the distance between the fourth lens 104 and the fifth lens 105 can be reduced. The fourth lens 104 can be one of the lenses with the maximum Abbe number. The Abbe number difference between the fourth lens 104 and the fifth lens 105 can be greater than 20 or greater than 25, and can be at most 55 or less. Therefore, the second lens group G2 can minimize chromatic aberration caused by changes in position depending on the operating mode.

[0074] The sixth lens 106 may have positive (+) or negative (-) refractive power on the optical axis OA, for example, it may have negative refractive power. The sixth lens 106 may comprise a plastic or glass material, and may be made of, for example, a plastic material. The sixth lens 106 may include an eleventh surface S11 defined as an object-side surface and a twelfth surface S12 defined as a sensor-side surface. The eleventh surface S11 may have a concave shape on the optical axis OA, and the twelfth surface S12 may also have a concave shape on the optical axis OA. That is, both surfaces of the sixth lens 106 may have concave shapes on the optical axis OA. Alternatively, the eleventh surface S11 may have a convex shape on the optical axis OA, and the twelfth surface S12 may also have a convex shape on the optical axis OA. That is, both surfaces of the sixth lens 106 may have convex shapes on the optical axis OA. Alternatively, the eleventh surface S11 may have a concave shape on the optical axis OA, and the twelfth surface S12 may have a convex shape on the optical axis OA. Alternatively, the eleventh surface S11 may have a convex shape on the optical axis OA, and the twelfth surface S12 may have a concave shape on the optical axis OA. At least one of the eleventh surface S11 and the twelfth surface S12 of the sixth lens 106 may be an aspherical surface. For example, both the eleventh surface S11 and the twelfth surface S12 may be aspherical. The aspherical coefficients of the eleventh surface S11 and the twelfth surface S12 may be determined by... Figure 6 L6S1 and L6S2 are represented in the diagram. The eleventh surface S11 and the twelfth surface S12 can be configured to have no critical point at the end of the effective region from the optical axis. The center thickness CT6 of the sixth lens 106 can be thinner than the edge thickness ET6. Therefore, incident light can be refracted in the optical axis direction due to the difference between the center thickness CT6 and the edge thickness ET6 of the sixth lens 106.

[0075] The seventh lens 107 may have a positive (+) or negative (-) refractive power on the optical axis OA, and may have a positive refractive power. The refractive power of the seventh lens 107 has a sign opposite to that of the refractive power of the sixth lens 106, thereby improving chromatic aberration. The seventh lens 107 may comprise a plastic or glass material, and may be, for example, a plastic material. The seventh lens 107 may comprise a thirteenth surface S13 defined as an object-side surface and a fourteenth surface S14 defined as a sensor-side surface. The thirteenth surface S13 may have a convex shape on the optical axis OA, and the fourteenth surface S14 may also have a convex shape on the optical axis OA. That is, both surfaces of the seventh lens 107 may have convex shapes on the optical axis OA. As another example, the thirteenth surface S13 may have a convex shape on the optical axis OA, while the fourteenth surface S14 may have a concave shape on the optical axis OA. Alternatively, the thirteenth surface S13 may have a concave shape on the optical axis OA, and the fourteenth surface S14 may have a convex shape on the optical axis OA. That is, the seventh lens 107 can have a meniscus shape that bulges toward the sensor on the optical axis OA. Alternatively, the thirteenth surface S13 can have a concave shape on the optical axis OA, and the fourteenth surface S14 can have a concave shape on the optical axis OA. That is, both surfaces of the seventh lens 107 can have concave shapes on the optical axis OA.

[0076] At least one of the thirteenth surface S13 and the fourteenth surface S12 of the seventh lens 107 can be an aspherical surface. For example, both the thirteenth surface S13 and the fourteenth surface S14 can be aspherical. The aspherical coefficients of the thirteenth surface S13 and the fourteenth surface S14 can be determined by... Figure 6 L7S1 and L7S2 are represented by these. The thirteenth surface S13 and the fourteenth surface S14 can be configured without a critical point at the end of the effective region from the optical axis. As another example, at least one of the thirteenth surface S13 and the fourteenth surface S14 of the seventh lens 107 can have a critical point between the optical axis and the end of the effective region, which is a point where the trend of the sagittal (Sag) value changes. That is, the critical point is a point on the lens surface where the sagittal value increases and then decreases, or where the sagittal value decreases and then increases. The sagittal value is the distance between the optical axis and the lens surface by a straight line perpendicular to the center of each lens surface. The sagittal value has a positive value at a position closer to the sensor than the center of each lens surface, and a negative value at a position closer to the object than the center of each lens surface.

[0077] The sixth lens 106 and the seventh lens 107 have refractive powers with opposite signs, and chromatic aberration can be controlled when the Abbe number difference is set to 10 or less. Therefore, the third lens group G3 can minimize chromatic aberration changes caused by positional variations depending on the mode, and thus function as an achromatic lens.

[0078] The eighth lens 108 may have a negative (-) refractive power at the optical axis OA. The eighth lens 108 may comprise a plastic or glass material, for example, a plastic material. The eighth lens 108 may include a fifteenth surface S15 defined as the object-side surface and a sixteenth surface S16 defined as the sensor-side surface. The fifteenth surface S15 may have a convex shape on the optical axis OA, and the sixteenth surface S16 may have a concave shape on the optical axis OA. That is, the eighth lens 108 may have a meniscus shape convex from the optical axis OA toward the object side. Alternatively, the eighth lens 108 may have a concave shape on the optical axis OA, and the sixteenth surface S16 may have a convex shape on the optical axis OA. That is, the eighth lens 108 may have a meniscus shape convex from the optical axis OA toward the sensor side.

[0079] At least one of the fifteenth surface S15 and the sixteenth surface S16 of the eighth lens 108 can be aspherical. For example, both the fifteenth surface S15 and the sixteenth surface S16 can be aspherical. The aspherical coefficients of the fifteenth surface S15 and the sixteenth surface S16 can be determined by... Figure 6 L8S1 and L8S2 are represented by these. At least one of the fifteenth surface S15 and the sixteenth surface S16 may have a critical point from the optical axis to the end of the effective region. For example, the sixteenth surface S16 may have a critical point between the optical axis and the end of the effective region. As another example, both the fifteenth surface S15 and the sixteenth surface S16 may have critical points. The center thickness CT8 of the aforementioned eighth lens 108 may be thinner than the edge thickness ET8. Therefore, the difference between the center thickness and the edge thickness of the aforementioned eighth lens 108, and light incident through the critical point of the sixteenth surface S16, can be refracted to the periphery of the image sensor 300.

[0080] The third lens group G3 described above can be the closest to the image sensor 300 among the multiple lens groups G1, G2, and G3. The third lens group G3 can move along the optical axis, and the optical axis distance BFL between the eighth lens 108 and the image sensor 300 can vary depending on the operating mode. Here, BFL is the optical axis distance from the center of the sensor-side surface of the eighth lens 108 to the image sensor 300. The third lens group G3 can play a role in controlling the principal ray angle CRA. Specifically, the CRA of the optical system 1000 according to the embodiment can be less than approximately 20 degrees, and the eighth lens 108 of the third lens group G3 can correct the principal ray angle of the light incident on the image sensor 300 according to each operating mode.

[0081] A camera module according to an embodiment of the present invention may include the optical system 1000 described above. The camera module is movable in the direction of the optical axis OA, including two lens groups G2 and G3 on the sensor side of a plurality of lens groups G1, G2, and G3 in the optical system 1000. The camera module may include a driving member (not shown) connected to the optical system 1000. The driving member is arranged outside the second lens group G2 and outside each of the third lens group G3, and can move in the direction of the optical axis OA according to an operating mode. The operating mode may include a first mode in which movement is performed at a first magnification, such as... Figure 2 As shown, and in which a third mode is performed with a second magnification different from the first magnification, such as Figure 3 As shown. In this case, the second magnification can be greater than the first magnification. Additionally, the operating mode can include a second mode, which has a magnification between the first and third modes, such as... Figure 1 As shown. Here, the first magnification can be the lowest magnification of the optical system 1000, and the second magnification can be the highest magnification of the optical system 1000. The first magnification can be about 1.5x or greater, for example, about 1.5x to about 5x, the second magnification can be about 6x to about 11x, and the third magnification can be about 4x to about 6x, which is between the first and second magnifications. The first mode can be a wide-angle mode, the second mode can be a medium telephoto mode, and the third mode can be a telephoto mode.

[0082] The driving components can move each of the second lens groups G2 and the third lens group G3 according to an operating mode selected from the first to the third modes, or operate them in an initial mode. Specifically, each of the plurality of driving components is connected to the second lens group G2 and the third lens group G3, and can move either the second lens group G2 or the third lens group G3 according to the operating mode. The initial mode can be one of the first, second, and third modes, such as the second mode or the mid-focus mode. For example, in the first mode, each of the second lens group G2 and the third lens group G3 can be positioned at a location defined as a first position (position 1). In the second mode, each of the second lens group G2 and the third lens group G3 can be positioned at a location defined as a second position (position 2) closer to the object than the first position. In the third mode, each of the second lens group G2 and the third lens group G3 can be positioned at a location defined as a third position (position 3) closer to the sensor than the first position. The first position can be the region between the second and third positions.

[0083] The first position of the second lens group G2 in the first mode can be the region between the second and third positions of the second lens group G2 in the second and third modes. The first position of the third lens group G3 in the first mode can be the region between the second and third positions of the third lens group G3 in the second and third modes.

[0084] According to the operating mode, at least one of the second lens group G2 and the third lens group G3 can be moved M1 and M2 along the optical axis OA, and the first lens group G1 can be positioned at a fixed position. According to the operating mode, the second lens group G2 can be moved M1 along the optical axis OA, and the first lens group G1 can be positioned at a fixed position. According to the operating mode, the third lens group G3 can be moved M2 along the optical axis OA, and the first lens group G1 can be positioned at a fixed position. In each of the first, second, and third positions according to the operating mode, the first to third lens groups G1, G2, and G3 can have a predetermined interval with adjacent lens groups. Therefore, the optical system 1000 can have a constant TTL (total lens length) and a variable BFL depending on the operating mode, and the effective focal length and magnification of the optical system 1000 can be controlled by controlling the positions of some lens groups. Furthermore, the optical axis spacing DG4 between the third lens group G3 and the filter 500 can be variable depending on the operating mode.

[0085] The effective length CA1 of the first lens 101 is the largest among the lenses, and the effective diameter CA6 of the sixth lens 106 is the smallest among the lenses. The effective length CA1 of the first lens 101 can be 5 mm or greater. The effective length CA6 of the sixth lens 106 can be less than 5 mm, for example, 3.8 mm or greater. In terms of absolute focal length, the focal length F2 of the second lens 102 can be the largest among the lenses. The absolute difference in focal length between two adjacent lenses can be the largest between the second lens 102 and the third lens 103, and the smallest between the sixth lens 106 and the seventh lens 107. The focal length of the fourth lens 104 can be the smallest among the lenses.

[0086] In the lenses of the first lens group G1, the center thickness CT1 of the first lens 101 can be the thickest. The absolute values ​​of the radii of curvature of the first to fourth surfaces S1, S2, S3, and S4 of the first lens 101 and the second lens 102 can be set to 5 mm or greater, so as not to significantly change the refraction angle of the incident light, and the light can be guided to the fourth lens 104 of the second lens group G2 by the third lens 103. The sum of the center thicknesses CT3 and CT4 of the third lens 103 and the fourth lens 104 of the second lens group G2 can be greater than the sum of the center thicknesses CT1, CT2, and CT3 of the first lens 101, the second lens 102, and the third lens 103. The sum of the center thicknesses CT3 and CT4 of the third lens 103 and the fourth lens 104 of the second lens group G2 can be greater than the sum of the center thicknesses CT6, CT7, and CT8 of the sixth lens 106, the seventh lens 107, and the eighth lens 108. Therefore, the second lens group G2 can guide the light incident through the first lens group G1 to the effective area of ​​the third lens group G3.

[0087] Depending on the magnification variation of the operating mode, the optical axis distance DG12 between the first lens group G1 and the second lens group G2, and the optical axis distance DG23 between the second lens group G2 and the third lens group G3, can be at least 0.2 mm or greater and at most 8 mm or less. Specifically, the optical axis distance DG12 between the first lens group G1 and the second lens group G2 can be moved by 0.2 mm or more, for example, within the range of 0.2 mm to 8 mm; and the optical axis distance DG23 between the second lens group G2 and the third lens group G3 can be moved by 1 mm or more, for example, within the range of 1 mm to 4 mm. Additionally, the center distance DG4 between the eighth lens 108 and the filter 500 can be moved by 1 mm or more, for example, within the range of 1 mm to 10 mm.

[0088] The relationships between DG12, DG23, and DG4 in the first, second, and third modes are as follows.

[0089] First Mode: DG4 <DG23<DG12

[0090] Second Mode: DG23 <DG12<DG4

[0091] Third Mode: DG12 <DG23<DG4

[0092] Depending on the operating mode, the optical system 1000 provides a brightness of 2.0 or greater with an F-number, and the F-number can be in the range of 2.2 to 3.8. The aperture stop can be located between the first lens group G1 and the second lens group G2.

[0093] The optical system 1000 according to the embodiment can satisfy at least one, two, or more of the mathematical formulas described below. Therefore, the optical system 1000 according to the embodiment can effectively correct aberrations that vary depending on the operating mode. Furthermore, the optical system 1000 according to the embodiment can effectively provide autofocus (AF) functionality for a given object at various magnifications and can have a slim and compact structure.

[0094] In the following text, the optical axis distance between two adjacent lenses can be defined as CG1 to CG7, from the distance between the first and second lenses to the distance between the seventh and eighth lenses. The effective length from the object-side surface and sensor-side surface of the first lens 101 to the object-side surface and sensor-side surface of the eighth lens 108 can be defined as CA11, CA12 to CA81 and CA82. The units for thickness values, distance values, and effective diameter values ​​are mm. Additionally, when the shape of the lens surface includes circular or non-circular shapes and the lens has a partially circular shape, the effective length can be defined as the effective length of the major axis or the maximum diameter.

[0095] [Formula 1] nL_G2>1 (nL is an integer greater than or equal to 2)

[0096] In Formula 1, nL_G2 represents the number of lenses included in the second lens group G2. Here, the following relationships can be established: nL_G1 > nL_G2, nL_G3 > nL_G2.

[0097] [Formula 2]0.7 <CA41 / CA11<1.5

[0098] In Formula 2, CA41 is the effective length of the seventh surface S7 of the fourth lens 104, and CA11 is the effective length of the first surface S1 of the first lens 101, or the effective length along its major axis. When Formula 2 is satisfied, a higher EPD (Entrance Pupil Diameter) compared to the optical system can be provided. Preferably, it can be 0.7. <CA41 / CA11<1。

[0099] [Formula 3]1 <CT1 / CT3<4

[0100] If Formula 3 satisfies the center thicknesses of the first lens 101 and the third lens 103, the aberration characteristics of the optical system 1000 can be improved. Preferably, Formula 3 satisfies 2. <CT1 / CT3<3.5。

[0101] [Formula 4]0 <CT1 / CT4<1

[0102] If Equation 4 satisfies the center thicknesses of the first lens 101 and the fourth lens 104, the optical system 1000 can improve the aberration characteristics. Preferably, 0.3 < CT1 / CT4 < 0.85 can be satisfied. The center thickness CT4 of the fourth lens 104 is the thickest among the lenses and has a convex shape on both surfaces, so that the fourth lens 104 can improve the light incident efficiency of the light incident on the first lens group G1 and can refract the light into the effective area of the sixth lens 106 having the minimum effective length.

[0103] [Equation 5] 1 < ET3 / CT3 < 4

[0104] In Equation 4, ET3 represents the thickness (mm) in the direction of the optical axis OA at the edge, which is the end of the effective area of the third lens 103. When the optical system 1000 according to the embodiment satisfies Equation 5, the optical system 1000 can improve the distortion characteristics of the light passing through the first lens group G1. Preferably, 2 < ET3 / CT3 < 2.5 can be satisfied.

[0105] Here, if the center thickness of the i-th lens is CTi and the edge thickness of the i-th lens is ETi, the ratio of CTi / ETi can be the largest when i = 4 and the smallest when i = 8. That is, the lens with the largest difference between the center thickness and the edge thickness can be arranged as the object-side lens of the second lens group G2, and the lens with the smallest difference between the center thickness and the edge thickness can be arranged as the sensor-side lens of the third lens group G3.

[0106] [Equation 6] FG1 < 0

[0107] In Equation 6, FG1 is the effective focal length EFL of the first lens group G1 and can have a value less than zero. FG1 is the combined focal length of the first to third lenses. If Equation 6 is satisfied, the optical aberration of the optical system, that is, the optical aberration of the first lens group G1, can be improved. The effective focal length of the second lens group G2 is FG2, and the effective focal length of the third lens is FG3, and the following equations can be satisfied.

[0108] [Equation 6-1]: FG2 * 2 < │FG1│

[0109] [Equation 6-2]: FG2 < │FG3│ < FG2 * 3 (* is multiplication)

[0110] [Equation 6-3]: │FG3│ < │FG1│

[0111] In this way, by adjusting the focal lengths of each lens group, the refraction angle of the light passing through the lens can be adjusted.

[0112] [Equation 7] CRA < 20

[0113] In Formula 7, CRA (Chief Ray Angle) is the angle of incidence of the chief ray. In the optical system, the angle of incidence of the chief ray can be less than 20 degrees, and can be 15 degrees or less, depending on the first, second, and third modes. The first mode can be a wide-angle mode, the second mode can be a mid-range mode, and the third mode can be a telephoto mode. Here, in field 1.0, the angle of incidence of the chief ray in the first mode (wide-angle) can be greater than that in the second mode. In the third mode (telephoto), the angle of incidence of the chief ray in field 1.0 can be 11 degrees or less, and the angle of incidence of the chief ray in the second mode can be less than that in the first mode. When Formula 6 is satisfied, the peripheral light ratio can be ensured.

[0114] [Formula 8](TTL / DG1)>3.5

[0115] In Formula 8, DG1 is the optical axis distance of the first lens group G1, for example, the optical axis distance from the center of the object-side surface of the first lens 101 to the center of the sensor-side surface of the third lens 103. For example, DG1 represents the distance (mm) on the optical axis OA between the first surface S1 of the first lens 101 and the sixth surface S6 of the third lens 103. TTL (Total Lens Length) represents the distance (mm) on the optical axis OA from the object-side first surface S1 of the first lens 101 to the upper surface of the image sensor 300. When the optical system 1000 according to the embodiment satisfies Formula 8, the optical system 1000 has a relatively small TTL and can ensure a peripheral light ratio.

[0116] Formula 8 may also include the following formulas.

[0117] [Formula 8-1](TTL / DG2)<(TTL / DG1)

[0118] [Formula 8-2]DG3 <DG2

[0119] Here, DG2 is the optical axis distance of the second lens group G2, and is the distance from the center of the object-side surface of the fourth lens 104 to the center of the sensor-side surface of the fifth lens 105. DG3 is the optical axis distance of the third lens group G3, and is the distance from the center of the object-side surface of the sixth lens 106 to the center of the sensor-side surface of the eighth lens 108.

[0120] [Formula 9]2 <TTL / EPD3<7

[0121] In Formula 9, EPD3 represents the size of the EPD of the optical system 1000 when operating in the third mode (i.e., telephoto mode). When the optical system 1000 according to the embodiment satisfies Formula 9, the optical system 1000 can ensure a bright image when operating in the third mode, and can be the minimum condition for ensuring an F-number of 4 or less in telephoto mode. Preferably, 3 can be satisfied. <TTL / EPD3<5。

[0122] [Formula 9-1]3 <TTL / EPD1<7

[0123] [Formula 9-2]2 <TTL / EPD2<7

[0124] [Formula 9-3] (TTL / EPD3) < (TTL / EPD2) < (TTL / EPD1)

[0125] In formulas 9-1 to 9-3, EPD1 is the size of the EPD of the optical system in the first mode (wide-angle mode), and EPD2 is the size of the EPD of the optical system in the second mode (medium-focus mode). When the optical system meets the above conditions, it can ensure a bright image according to each mode.

[0126] [Formula 10]2 <CT_Max / CT_Min<6

[0127] In Formula 10, CT_Max is the thickest thickness at the center of the lens, and CT_Min is the thinnest thickness at the center of the lens. Satisfying Formula 10 improves the aberration characteristics of the optical system. Preferably, it satisfies 3... <CT_Max / CT_Min<5.5。

[0128] [Formula 11]1 <CA_Max / CA_Min<3

[0129] In Equation 11, CA_Max is the maximum effective length of each lens surface, and CA_Min is the minimum effective diameter of each lens surface. When Equation 11 is satisfied, the optical performance of the optical system can be maintained, and a camera module for a thin or compact structure can be provided. Preferably, Equation 1 is satisfied. <CA_Max / CA_Min<1.5。

[0130] [Formula 12]0.1<ΣCG_Wide / TTL<0.6

[0131] In Formula 12, ΣCG is the sum of the center distances between adjacent lenses, and ΣCG_Wide is the sum of the center distances between adjacent lenses in the first mode. When the optical system satisfies Formula 12, the center distance DG12 between the first lens group and the second lens group, and the center distance between the second lens group and the third lens group, can be set according to the wide-angle mode. The center distance DG12 between the first lens group and the second lens group can be the center distance CG3 between the third lens 103 and the fourth lens 104, and varies according to the operating mode. The center distance DG23 between the second lens group and the third lens group is the center distance CG5 between the fifth lens 105 and the sixth lens 106, and varies according to the operating mode. Preferably, 0.3 < ΣCG_Wide / TTL < 0.5 can be satisfied.

[0132] [Formula 12-1] 0.05 < ΣCG_Mid / TTL < 0.4

[0133] [Formula 12-2] 0 < ΣCG_Tele / TTL < 0.3

[0134] In formulas 12-1 and 12-2, ΣCG_Mid is the sum of the center distances between adjacent lenses in the second mode, and ΣCG_Tele is the sum of the center distances between adjacent lenses in the third mode. When the optical system satisfies formulas 12-1 and 12-2, the center distance DG12 between the first lens group and the second lens group, and the center distance between the second lens group and the third lens group, can be set according to the mid-focal mode and the telephoto mode. Preferably, the condition ΣCG_Tele < ΣCG_Mid < ΣCG_Wide can be satisfied. When the optical system 1000 according to the embodiment satisfies at least one or two or more of formulas 1 to 12, the optical system 1000 can have a slim structure. In addition, the optical system 1000 can have improved assembly characteristics and a mechanically stable shape.

[0135] [Formula 13]0.5 <DG1 / DG2<2

[0136] In Formula 13, DG1 is the optical axis distance of the first lens group G1, and DG2 is the optical axis distance of the second lens group G2. By setting the optical axis distances of the first lens group G1 and the second lens group G2 in Formula 13, the TTL can be adjusted. Preferably, it can satisfy 0.5. <DG1 / DG2<1.2。

[0137] [Formula 14]0.5 <DG2 / DG3<2

[0138] In Equation 14, DG2 is the optical axis distance of the second lens group G2, and DG3 is the optical axis distance of the third lens group G3. Preferably, 0.9 < DG2 / DG3 < 1.3 can be satisfied. When the optical system 1000 according to the embodiment satisfies at least one of Equation 13 and Equation 14, it has a relatively small TTL and can provide various magnification ratios according to at least three mode changes.

[0139] [Equation 15] 0 < CG2 / TTL < 0.2

[0140] In Equation 15, CG2 is the optical axis distance between the second lens 102 and the third lens 103. When the optical system 1000 satisfies Equation 15, the optical system 1000 has a relatively small TTL and can control the stray light incident on the first lens group G1 to have improved optical characteristics. Preferably, 0 < CG2 / TTL < 0.1 can be satisfied.

[0141] [Equation 16] 2 < TTL / (DG2 + DG3) < 5

[0142] Equation 16 sets the TTL and the sum of the optical axis distances of the second lens group G2 and the third lens group G3, and when the optical system 1000 satisfies Equation 16, the optical system 1000 has a relatively small TTL and can improve the chromatic aberration characteristics. Preferably, 2.2 < TTL / (DG2 + DG3) < 3 can be satisfied.

[0143] [Equation 17] 20 < Vd4 - Vd5 < 70

[0144] In Equation 17, Vd4 represents the Abbe number of the fourth lens 104, and Vd5 represents the Abbe number of the fifth lens 105. When the absolute value of the difference in Abbe numbers between the fourth lens and the fifth lens of the optical system 1000 according to the embodiment satisfies Equation 17, the optical system 1000 can improve the chromatic aberration characteristics. Preferably, Vd5 < Vd4 and 40 < Vd4 are satisfied.

[0145] [Equation 18] 15 < |Vd8 - Vd7| < 60

[0146] In Equation 18, Vd8 represents the Abbe number of the eighth lens, and Vd7 represents the Abbe number of the seventh lens. If the absolute value of the difference in Abbe numbers between the seventh lens and the eighth lens satisfies Equation 18, the optical system 1000 can improve the chromatic aberration characteristics. Preferably, Vd7 < Vd8 and 40 < Vd8 can be satisfied.

[0147] [Equation 19] 1.6 < Nd1

[0148] In Equation 19, Nd1 represents the refractive index of the d-line of the first lens 101. If the optical system 1000 according to the embodiment satisfies Equation 19, the incident light can be dispersed, and the effective area of the lens arranged behind the first lens 101 can be ensured. Preferably, 1.65 < Nd1 can be satisfied.

[0149] [Equation 19-1] 1.6 < Nd5

[0150] [Equation 19-2] 1.6 < Nd7

[0151] The refractive indices of the fourth lens 104 and the eighth lens 108 can be less than 1.6. Among the lenses, the number of lenses with a refractive index greater than 1.60 can be greater than the number of lenses with a refractive index less than 1.60.

[0152] [Equation 20] 1 < L1R1 / L3R2 < 3.5

[0153] In Equation 20, L1R1 represents the radius of curvature of the first surface S1 on the object side of the first lens 101, and L3R2 represents the radius of curvature of the sixth surface S6 on the sensor side of the third lens 103. When the optical system 1000 according to the embodiment satisfies Equation 20, the optical system 1000 can control the stray light incident on the first lens group G1. Preferably, 2 < L1R1 / L3R2 < 3 can be satisfied. Since the third lens 103 has a concave surface on the sensor side on the optical axis, an increase in the effective diameter of the fourth lens 104 can be suppressed.

[0154] [Equation 21] 1.5 < L1R1 / L4R1 < 3.5

[0155] In Equation 21, L1R1 represents the radius of curvature of the first surface S1 on the object side of the first lens 101, and L4R1 represents the radius of curvature of the seventh surface S7 on the object side of the fourth lens 104. When the optical system 1000 according to the embodiment satisfies Equation 21, the optical system 1000 can have good optical performance at various magnifications. Preferably, 2 < L1R1 / L4R1 < 3 can be satisfied.

[0156] [Equation 22] 0 < L3R2 / L4R1 < 2

[0157] In Equation 22, L3R2 represents the radius of curvature of the sixth surface S6 on the sensor side of the third lens 103, and L4R1 represents the radius of curvature of the seventh surface S7 on the object side of the fourth lens 104. When the optical system 1000 according to the embodiment satisfies Equation 22, when operating at various magnification ratios in at least three modes, the optical system 1000 can have good optical performance at the periphery of the field of view (FOV). Preferably, 0.5 < L3R2 / L4R1 < 1.5 can be satisfied. The fourth lens 104 is the first lens of the second lens group G2, has a biconvex shape on the optical axis, and the fourth lens 104 can have a positive optical power. Therefore, the distance between the convex sensor-side surface of the fourth lens 104 and the concave object-side surface of the fifth lens 105 can be closely closed.

[0158] [Equation 23] 1 < L1R1 / L8R2 < 3

[0159] In Equation 23, L8R2 represents the radius of curvature of the sixteenth surface S16 on the sensor side of the eighth lens 108. When the optical system 1000 satisfies Equation 23, the optical system 1000 can have good optical performance at the center and periphery of the field of view (FOV). Preferably, 2 < L1R1 / L8R2 < 3 can be satisfied.

[0160] Here, if the radius of curvature of the object-side surface of the i-th lens is R1i and the radius of curvature of the sensor-side surface is R2i, the absolute value of R1i / R2i can be the largest when i = 3 and the smallest when i = 1. For example, when i = 3, the absolute value of R13 / R23 is 50 or greater, and when i = 1, the absolute value of R11 / R21 is 0.5 or less. In addition, the lenses for which the absolute value of R1i / R2i is less than 1 can be i = 1, 2, 4, 5, 7.

[0161] [Equation 24] 0 < Md12_mG2 / TTL < 0.5

[0162] In Equation 24, Md12_mG2 represents the difference in the central distance (unit: mm) after the second lens group G2 moves when changing from the second mode to the first mode or from the first mode to the second mode. Specifically, Md12_mG2 represents the moving distance of the second lens group G2 in the first mode and the second mode, and represents the difference between the optical axis distance between the first lens group G1 and the second lens group G2 in the first mode and the optical axis distance between the first lens group G1 and the second lens group G2 in the second mode. When the optical system 1000 according to the embodiment satisfies Equation 24, the optical system 1000 can minimize the moving distance of the second lens group G2 when the magnification changes, so that the optical system 1000 can have a thin structure. In addition, since the moving distance can be minimized when controlling the position of the second lens group G2, improved power consumption characteristics can be achieved. Preferably, 0 < Md12_mG2 / TTL < 0.2 can be satisfied.

[0163] [Equation 25] 0 < Md23_mG2 / TTL < 0.5

[0164] In Equation 25, Md23_mG2 represents the difference in the central distance (unit: mm) after the second lens group G2 moves when operating from the second mode to the third mode or from the third mode to the second mode. Specifically, Md23_mG2 represents the difference between the optical axis distance between the first lens group G1 and the second lens group G2 in the second mode and the optical axis distance between the first lens group G1 and the second lens group G2 in the third mode. The maximum moving distance of the second lens group G2 can be greater than the maximum moving distance of the third lens group G3. When the optical system 1000 according to the embodiment satisfies Equation 25, the optical system 1000 can minimize the moving distance of the second lens group G2 when the magnification changes, so that the optical system 1000 can have a thin structure. In addition, the moving distance can be minimized when controlling the position of the second lens group G2, so improved power consumption characteristics can be achieved. 0 < Md23_mG2 / TTL < 0.1 can be satisfied. In addition, the condition Md23_mG2 < Md12_mG2 can be satisfied.

[0165] [Equation 26] 0.3 < Md12_mG2 / DG2 < 1

[0166] Equation 26 can set the moving distance of the second lens group G2 and the optical axis distance of the second lens group G2. When the optical system 1000 satisfies Equation 26, the optical system 1000 can minimize the moving distance of the second lens group G2 when the magnification changes, so that the optical system 1000 can have a thin structure. In addition, the moving distance can be minimized when controlling the position of the second lens group G2, so improved power consumption characteristics can be achieved. Preferably, 0.3 < Md12_mG2 / DG2 < 0.8 can be satisfied.

[0167] [Formula 27]0 <Md23_mG3 / DG3<0.5

[0168] In Formula 27, Md23_mG3 represents the difference in center distance after the movement of the third lens group G3 when changing from the second mode to the first mode or from the first mode to the second mode. When the optical system 1000 satisfies Formula 27, the optical system 1000 can minimize the movement distance of the third lens group G3 when the magnification changes, allowing the optical system 1000 to have a slim structure. Furthermore, by minimizing the movement distance when controlling the position of the third lens group G3, improved power consumption characteristics can be achieved. Preferably, 0.1 is satisfied. <Md23_mG3 / DG3<0.4。

[0169] [Formula 28]1<(CT1 / ET1) / (CT3 / ET3)<5

[0170] In Formula 28, CT1 / ET1 is the value obtained by dividing the thickness of the optical axis of the first lens 101 by the thickness of its end, and CT3 / ET3 is the value obtained by dividing the thickness of the optical axis of the third lens 103 by the thickness of its end. If the values ​​obtained by dividing the center thickness and end thickness of the first lens 101 and the third lens 103 satisfy Formula 28 with the above ratio, chromatic aberration can be improved and incident light can be controlled. Preferably, 2 < (CT1 / ET1) / (CT3 / ET3) < 4 can be satisfied.

[0171] [Formula 29]0<(CT1 / ET1) / (CT7 / ET7)<1

[0172] In Formula 29, CT1 / ET1 is a value obtained by dividing the thickness of the seventh lens 107 at the optical axis by its thickness at the end. If the value obtained by dividing the center thickness and end thickness of the first lens 101 and the seventh lens 107 satisfies Formula 29 with the aforementioned ratio, chromatic aberration can be improved and incident light can be controlled. Preferably, 0.5 < (CT1 / ET1) / (CT7 / ET7) < 1 can be satisfied.

[0173] [Formula 30]1 <Md1(DG12 / DG23)<5

[0174] In Formula 30, Md1(DG12 / DG23) represents the ratio between the center distance DG12 between the first lens group and the second lens group and the center distance DG23 between the second lens group and the third lens group in the first mode. When the optical system 1000 according to the embodiment satisfies Formula 30, the optical system 1000 can have improved optical characteristics at the first magnification. Specifically, the optical system 1000 can have improved aberration characteristics at the first magnification and can improve the optical performance at the center and periphery of the field of view (FOV). Preferably, it can satisfy Formula 1. <Md1(DG12 / DG23)<3。

[0175] [Formula 31]0 <Md3(DG12 / DG23)<0.7

[0176] In Formula 31, Md3(DG12 / DG23) represents the ratio between the center distance DG12 between the first and second lens groups and the center distance DG23 between the second and third lens groups in the third mode. When the optical system 1000 according to the embodiment satisfies Formula 31, the optical system 1000 can have improved optical characteristics at the second magnification. Specifically, the optical system 1000 can have improved aberration characteristics at the second magnification and can improve the optical performance at the periphery of the field of view (FOV). Preferably, 0 can be satisfied. <Md3(DG12 / DG23)<0.5。

[0177] [Formula 32]0.5 <TD2 / TTL<1

[0178] In Formula 32, TD2 is the optical axis distance from the center of the object-side surface of the first lens to the center of the sensor-side surface of the eighth lens in the second mode. When the optical system 1000 according to the embodiment satisfies Formula 32, the optical system 1000 can have improved optical characteristics in a mid-focal mode, which is the second mode. Specifically, the optical system 1000 can have improved aberration characteristics in the mid-focal mode and can improve the optical performance of the peripheral portion of the field of view (FOV). Preferably, 0.65 can be satisfied. <TD2 / TTL<0.9。

[0179] [Formula 33]1 <TD1 / TD2<1.5

[0180] In Equation 33, TD1 is the optical axis distance from the center of the object side surface of the first lens to the center of the sensor side surface of the eighth lens in the first mode. When the optical system 1000 according to the embodiment satisfies Equation 33, the optical system 1000 can have improved optical characteristics in the first mode and the second mode, and can reduce the influence on TTL. Specifically, the optical system 1000 can have improved aberration characteristics in the first mode and the second mode, and can improve the optical performance of the peripheral portion of the field of view (FOV). Preferably, 1 < TD1 / TD2 < 1.4 can be satisfied.

[0181] [Equation 33-1] 0.5 < TD1 / TTL < 2

[0182] Preferably, 0.5 < TD1 / TTL < 1 can be satisfied. The relationship between the maximum optical axis distance TD1 and TTL according to each mode can be set.

[0183] [Equation 33-2] 1 < TD1 / TD3 < 1.5

[0184] In Equation 33-2, TD3 is the optical axis distance from the center of the object side surface of the first lens to the center of the sensor side surface of the eighth lens in the third mode. The optical system 1000 can have improved optical characteristics in the first mode and the third mode, and can reduce the influence on TTL.

[0185] [Equation 34] 10 mm < TD3 < TD2 < TD1 < 22 mm

[0186] Equation 34 is a diagram comparing the optical axis distances of the lenses in the first, second, and third modes. TD3 is the optical axis distance from the center of the object side surface of the first lens to the center of the sensor side surface of the eighth lens in the third mode. When the optical system 1000 according to the embodiment satisfies Equation 34, the optical system 1000 can have improved optical characteristics in the first, second, and third modes. Specifically, the optical system 1000 can have improved aberration characteristics in the first, second, and third modes, and can improve the optical performance in the peripheral portion of the field of view (FOV).

[0187] [Equation 35] 0.1 < BFL2 / TTL < 1

[0188] In Formula 35, BFL2 (back focal length 1) is the optical axis distance from the center of the sensor-side surface of the eighth lens to the upper surface of the image sensor in the second mode. When the optical system 1000 according to the embodiment satisfies Formula 35, the optical system 1000 can adjust the focal position to the upper surface of the image sensor 300 in the second mode. Specifically, the optical system 1000 has improved optical characteristics in the second mode and can improve the peripheral optical performance of the field of view (FOV). Preferably, 0.2 can be satisfied. <BFL2 / TTL<0.5。

[0189] [Formula 36]2 <BFL3 / BFL1<4

[0190] In Formula 36, ​​BFL3 is the optical axis distance from the center of the sensor-side surface of the eighth lens to the upper surface of the image sensor in the third mode. When the optical system 1000 according to the embodiment satisfies Formula 36, ​​the optical system 1000 can adjust the focal position to the upper surface of the image sensor 300 in both the first and third modes. Specifically, the optical system 1000 has improved optical characteristics in both the first and third modes and can improve the peripheral optical performance of the field of view (FOV). Preferably, 2.5 can be satisfied. <BFL3 / BFL1<3.1。

[0191] [Formula 37]1 <TD3 / BFL3<3

[0192] Formula 37 is a value comparing the optical axis distance TD3 between the center of the object-side surface of the first lens and the center of the sensor-side surface of the eighth lens in the third mode, and the optical axis distance BFL3 from the center of the sensor-side surface of the eighth lens 108 to the upper surface of the image sensor. When the optical system 1000 according to the embodiment satisfies Formula 37, the optical system 1000 can have improved optical characteristics in the third mode. Specifically, the optical system 1000 can have improved aberration characteristics in the third mode and improved optical performance in the periphery of the field of view (FOV). Preferably, 1.3 can be satisfied. <TD3 / BFL3<2.1。

[0193] [Formula 38]2 <Md_CG_Max / Md_CG_Min<8

[0194] In Formula 38, Md_CG_Max represents the maximum center distance among the center distances between the first and eighth lenses in the first, second, and third modes, and Md_CG_Min represents the minimum center distance among the center distances between the first and eighth lenses in the first, second, and third modes. When the optical system satisfies Formula 38, the TTL and the optical axis distance of the lenses can be adjusted according to each mode. Preferably, 4... <Md_CG_Max / Md_CG_Min<7。

[0195] [Formula 39]1mm <BFL1<6mm

[0196] Formula 39 represents the optical axis distance between the eighth lens and the image sensor in the first mode. When the optical system satisfies Formula 39, the focal position facing the upper surface of the image sensor in the first mode can be adjusted. Preferably, it can include 2mm. <BFL1<3.5mm。

[0197] [Formula 40]20 <Aver_Vd<45

[0198] In Equation 40, Aver_Vd is the average Abbe number of the first to eighth lenses. When the optical system satisfies Equation 40, the optical system 1000 can have improved aberration characteristics and resolution. Preferably, it can satisfy 25. <Aver_Vd<40。

[0199] [Formula 41]1.5 <Aver_Nd<1.8

[0200] In Equation 40, Aver_Nd is the average refractive index of the first to eighth lenses. When the optical system satisfies Equation 41, the optical system 1000 can have improved aberration characteristics and resolution. Preferably, it can satisfy 1.58. <Aver_Nd<1.68。

[0201] [Formula 41-1]10<∑Vd / ∑Nd<40

[0202] In Formula 41-1, ∑Vd represents the sum of the Abbe numbers of each of the plurality of lenses. ∑Nd represents the sum of the refractive indices of each of the plurality of lenses. When the optical system 1000 according to the embodiment satisfies Formula 41-1, the optical system 1000 can have improved aberration characteristics and resolution. Preferably, Formula 41-1 can satisfy 17 < ∑Vd / ∑Nd < 25. Preferably, the condition (∑Vd - ∑Nd) < 250 can be satisfied.

[0203] [Formula 42]2<│FG1 / FG2│<4

[0204] In Formula 42, FG1 represents the effective focal length (EFL) of the first lens group G1, and FG2 represents the effective focal length of the second lens group G2. FG2 is the combined focal length of the fourth and fifth lenses. If Formula 42 is satisfied, the size of the optical system can be reduced, for example, the total lens length (TTL). Preferably, FG2 > 0. FG3 is the combined focal length of the sixth to eighth lenses, and FG3 < 0, and the condition |FG1| > |FG3| > FG2 can be satisfied. Preferably, 2 < |FG1 / FG2| < 3.5 can be satisfied.

[0205] [Equation 43] 1 < FMd2 / FMd1 < 10

[0206] In Equation 43, FMd1 is the effective focal length of the optical system in the first mode, and FMd2 is the effective focal length of the optical system in the second mode. Preferably, 1 < FMd2 / FMd1 < 3 can be satisfied. When the optical system satisfies Equation 43, the effective focal length can be adjusted according to the first mode and the second mode.

[0207] [Equation 43-1] 1 < FMd3 / FMd2 < 10

[0208] In Equation 43, FMd3 is the effective focal length of the optical system in the third mode. Preferably, 1 < FMd3 / FMd2 < 2 can be satisfied, and the condition: (FMd3 / FMd1) > (FMd3 / FMd2) can be satisfied. When the optical system satisfies Equation 43-1, the effective focal length can be adjusted according to the second mode and the third mode.

[0209] In the first mode, the effective focal length Fmd1 of the optical system and the focal length of each lens can satisfy the following conditions.

[0210] Condition 1: 2 < │F1 / Fmd1│ < 7

[0211] Condition 2: 1.5 < F2 / Fmd1 < 4

[0212] Condition 3: 0.6 < │F3 / Fmd1│ < 1.6

[0213] Condition 4: 0 < F4 / Fmd1 < 1

[0214] Condition 5: 2 < │F5 / Fmd1│ < 4

[0215] Condition 6: 0.5 < │F6 / Fmd1│ < 1.5

[0216] Condition 7: 0.5 < F7 / Fmd1 < 1.5

[0217] Condition 8: 0.6 < │F8 / Fmd1│ < 1.6

[0218] In the second mode, the effective focal length Fmd2 of the optical system and the focal length of each lens can satisfy the following conditions.

[0219] Condition 1: 0 < │F1 / Fmd2│ < 1

[0220] Condition 2: 1 < F2 / Fmd2 < 4

[0221] Condition 3: 1 < │F3 / Fmd2│ < 2

[0222] Condition 4: 2 < F4 / Fmd2 < 4

[0223] Condition 5: 0 < |F5 / Fmd2| < 1

[0224] Condition 6: 1 < |F6 / Fmd2| < 3

[0225] Condition 7: 1 <F7 / Fmd2<3

[0226] Condition 8: 1 < |F8 / Fmd2| < 3

[0227] In the third mode, the effective focal length Fmd3 of the optical system and the focal length of each lens can satisfy the following conditions.

[0228] Condition 1: 0 < |F1 / Fmd3| < 1

[0229] Condition 2: 0.8 <F2 / Fmd3<2

[0230] Condition 3: 1 < |F3 / Fmd3| < 2.5

[0231] Condition 4: 3 <F4 / Fmd3<6

[0232] Condition 5: 0 < |F5 / Fmd3| < 1

[0233] Condition 6: 1 < |F6 / Fmd3| < 3

[0234] Condition 7: 1 <F7 / Fmd3<3

[0235] Condition 8: 1 < |F8 / Fmd3| < 2.8

[0236] [Formula 44]2 <FMd2 / EPD2<7

[0237] In Formula 44, FMd2 is the effective focal length of the optical system in the second mode (mid-focal), and EPD2 represents the size of the entrance pupil (entrance pupil diameter, EPD) of the optical system 1000 in the second mode. When the optical system 1000 according to the embodiment satisfies Formula 44, the optical system 1000 can ensure a bright image during operation in the second mode. Preferably, it can satisfy Formula 2. <FMd2 / EPD2<4。

[0238] [Formula 45]0.1 <FMd1 / EPD1<3

[0239] In formula 34, FMd1 is the effective focal length of the optical system in the first mode (wide-angle), and EPD1 represents the size of the entrance pupil (entrance pupil diameter, EPD) of the optical system 1000 when operating in the first mode. When the optical system 1000 according to the embodiment satisfies formula 45, the optical system 1000 can ensure a bright image when operating in the first mode. Preferably, it can satisfy formula 1. <FMd1 / EPD1<3。

[0240] [Formula 46]FMd1 <FMd2<FMd3

[0241] In Equation 46, FMd1, FMd2, and FMd3 represent the effective focal lengths of the optical system in the first, second, and third modes, respectively. The effective focal length in the third mode can be the largest, and the effective focal length in the first mode can be the smallest.

[0242] [Formula 47]0 <TTL / FMd2<2

[0243] Formula 47 can adjust the TTL by comparing the effective focal length in the TTL and the second mode. Preferably, it can satisfy 1 <TTL / FMd2<2。

[0244] [Formula 48]0.1 <TTL / FMd1<5

[0245] Formula 47 adjusts the TTL by comparing the TTL with the effective focal length in the first mode. Preferably, it satisfies 1 <TTL / FMd1<3。

[0246] [Formula 49]1 <CA_Max / ImgH<3

[0247] In Formula 49, CA_Max represents the maximum effective length (CA) of the lens surfaces of the plurality of lenses included in the optical system 1000. ImgH is the distance from the 0 field of view region of the image sensor 300 centered on the image surface overlapping with the optical axis OA to the 1.0 field of view region of the image sensor 300. ImgH represents half of the maximum diagonal length of the effective area of ​​the image sensor 300. When the optical system 1000 according to the embodiment satisfies Formula 49, the optical system 1000 can be provided in a thin and compact manner. In addition, the optical system 1000 can achieve high resolution and high image quality. ImgH ranges from 2 mm or greater, for example, from 2 mm to 3 mm. Here, the effective lengths CA1 to CA8 of the first to eighth lenses 101 to 108 can satisfy the following conditions.

[0248] Condition 1: 0.5 <CA1 / (Imgh*2)<1.5

[0249] Preferably, CA1>(Imgh*2) can be satisfied.

[0250] Condition 2: 0.4 < CA2 / (Imgh*2) < 1.4

[0251] Preferably, CA2 > (Imgh*2) can be satisfied.

[0252] Also, CA3 < (Imgh*2), CA5 < (Imgh*2), CA6 < (Imgh*2), CA7 < (Imgh*2), CA8 < (Imgh*2) can be satisfied. In addition, CA4 > (Imgh*2) can also be satisfied.

[0253] When the effective length of the object-side surface of the first lens 101 is CA11 and the effective length of the sensor-side surface is CA12, the following conditions can be satisfied.

[0254] Condition 1: 1 < CA11 / (Imgh*2) < 1.5

[0255] Condition 2: 0.8 < CA12 / (Imgh*2) < 1.2

[0256] [Formula 50] 5 < TTL / ImgH < 12

[0257] If the optical system 1000 satisfies Formula 50, the optical system 1000 can have a smaller TTL, such that the optical system 1000 can be provided in a thin and compact manner. Preferably, it can be in the range of 6 < TTL / ImgH < 10.

[0258] [Formula 51] 1 < BFL2 / ImgH < 3

[0259] If the optical system 1000 according to the embodiment satisfies Formula 51, the BFL required for a small image sensor smaller than 1 inch can be ensured. Additionally, when the optical system 1000 satisfies Formula 51, the optical system 1000 can operate at various magnifications while maintaining the TTL, and can have excellent optical characteristics at the center and periphery of the field of view (FOV). Preferably, it can be in the range of 2 < BFL2 / ImgH < 3.

[0260] [Formula 52] 2 < BFL3 / ImgH < 4

[0261] When the optical system 1000 according to the embodiment satisfies Formula 52, the BFL required for a small image sensor smaller than 1 inch can be ensured. When the optical system 1000 satisfies Formula 52, the optical system 1000 can operate at various magnifications while maintaining the TTL, and can have excellent optical characteristics at the center and periphery of the field of view (FOV). Preferably, 2.5 < BFL3 / ImgH < 3.5 can be satisfied.

[0262] [Formula 53]1 <EPD1<EPD2<EPD3<7

[0263] In Formula 53, EPD1, EPD2, and EPD3 represent the entrance pupil sizes of the optical systems according to the first to third modes, and the brightness can be adjusted according to each mode.

[0264] [Formula 54]0 <Max_Distortion<3

[0265] In Equation 54, distortion represents the maximum or peak value of the distortion from the center (0.0F) to the diagonal end (1.0F) of the image sensor, based on the optical characteristics detected by the image sensor 300. When the optical system 1000 satisfies Equation 54, the optical system 1000 can improve distortion characteristics and set conditions for image processing. Preferably, Max_Distortion < 1.5 can be satisfied.

[0266] [Formula 55] 8° <FOV3<FOV2<FOV1<45°

[0267] In Formula 55, FOV1, FOV2, and FOV3 represent the diagonal angles of the optical system in the first, second, and third modes. FOV (field of view) represents the diagonal viewing angle (degrees) of the optical system 1000, and can provide an optical system with angles less than 45 degrees. Furthermore, the relationship between the viewing angles FOV1, FOV2, and FOV3 of each mode and the optical axis distances BFL1, BFL2, and BFL3 between the last lens and the image sensor 300 can satisfy the following conditions.

[0268] Condition 1: 5 <FOV1 / BFL1<15

[0269] Condition 2: 2.5 <FOV2 / BFL2<5

[0270] Condition 3: 1 <FOV3 / BFL3<2.5

[0271] [Formula 56]

[0272]

[0273] In Equation 56, Z is the sag, which can represent the distance from any position on the aspherical surface to the vertex of the aspherical surface along the optical axis. Y can represent the distance from any position on the aspherical surface to the optical axis in the direction perpendicular to the optical axis. c can represent the curvature of the lens, and K can represent the conic constant. A, B, C, D, E, and F can represent aspherical constants.

[0274] The optical system 1000 according to the embodiment can satisfy at least one of the above formulas 1 to 55. Therefore, the optical system 1000 and the camera module can have improved optical characteristics. In detail, since the optical system 1000 satisfies at least one or more of the above formulas 1 to 55, it can effectively compensate for the degradation of optical characteristics caused by the movement of the lens group, such as chromatic aberration, vignetting, diffraction effects, and image quality degradation in the peripheral region. In addition, the optical system 1000 according to the embodiment can significantly reduce the movement distance of the lens group and provide autofocus AF function for various magnifications with excellent power consumption characteristics.

[0275] Since the optical system 1000 according to the embodiment satisfies at least one or more of the above formulas 1 to 55, it can have improved assembly performance and mechanical stability, and can be provided with a thin structure, so that the optical system 1000 and the camera module including the optical system can have a compact structure.

[0276] The optical system 1000 according to an embodiment and the changes from the first mode to the third mode will be described in more detail below. In the optical system 1000 according to an embodiment, the first lens group G1 may be fixed, and the second lens group G2 and the third lens group G3 may be movable according to the operating mode. The first lens group G1 may include three lenses, for example, the first to third lenses 101, 102 and 103, and the second lens group G2 may include two lenses, for example, the fourth lens 104 and the fifth lens 105. In addition, the third lens group G3 may include three lenses, for example, the sixth to eighth lenses 106, 107 and 108. In the optical system 1000 according to an embodiment, the object-side surface (seventh surface S7) of the fourth lens 104 may be used as an aperture, and the filter 500 described above may be arranged between the fourth lens group G4 and the image sensor 300.

[0277] Figure 5 The diagram shows the radius of curvature along the optical axis OA of the first lens 101 to the eighth lens 108, the center thickness CT of the lens, the adjacent components between lenses (e.g., the center distance CG), the refractive index at the d-line, the Abbe number, and the effective length CA. Figure 5 In this context, DG4 is the optical axis distance between the eighth lens and the filter 500, and it can vary depending on the movement of the third lens group G3.

[0278] [Table 1]

[0279]

[0280] Referring to Table 1, the ratio CT / ET of the center thickness CT and the edge thickness ET of each lens can be different from each other. The CT / ET value of the fourth lens 104 can be the largest, and the CT / ET value of the eighth lens can be the smallest. Figure 1 and Figure 2 As shown, the Abbe number Vd4 of the fourth lens 104, included in the second lens group G2, can be 20 or higher than the Abbe number Vd5 of the fifth lens 105. Because the fourth lens 104 and the fifth lens 105 have the aforementioned Abbe number difference, chromatic aberration changes that occur when the magnification changes according to the movement M1 of the second lens group G2 can be minimized. Figure 1 and Figure 3 As shown, the Abbe number Vd8 of the eighth lens 108 included in the third lens group G3 can be 20 or more, or 30 or more, higher than the Abbe number Vd7 of the seventh lens 107. Because the seventh lens 107 and the eighth lens 108 have the aforementioned Abbe number difference, chromatic aberration changes that occur when the magnification changes according to the movement M2 of the third lens group G3 can be minimized and / or compensated, thereby performing an achromatic function.

[0281] The camera module according to the embodiment can acquire information about an object at various magnifications. Specifically, the driving member can control the positions of the second lens group G2 and the third lens group G3, thereby enabling the camera module to operate at various magnifications. For example, refer to... Figure 1 , Figure 8 and Figure 11 The camera module, including the optical system 1000, can operate in a first mode with a first magnification. The first magnification can be approximately 3x to approximately 5x. Specifically, in an embodiment, the first magnification can be approximately 3.5x. In the first mode, each of the second lens group G2 and the third lens group G3 can be moved to a predetermined position. Therefore, each of the first to third lens groups G3 can be arranged at predetermined intervals. For example, the second lens group G2 can be positioned in a region spaced apart from the first lens group G1 by a first interval DG12, and the third lens group G3 can be positioned in a region spaced apart from the second lens group G2 by a second interval DG23. Here, the first interval DG12 and the second interval DG23 can refer to the interval between the lens groups on the optical axis OA and can vary depending on the operating mode.

[0282] When the camera module operates in the first mode, the optical system 1000 may have a TTL (total lens length) value and a BFL1 value at a first position. Additionally, the optical system 1000 may have an FMD1 defined as a first effective focal length (EFL) at the first position. Furthermore, in the first mode, the field of view (FOV) of the camera module may be less than approximately 35 degrees, and the F-number may be less than approximately 3. When the camera module operates in the second mode, the optical system 1000 may have a TTL (total lens length) value and a BFL2 value at a second position. Additionally, the optical system 1000 may have an FMD2 defined as a second effective focal length (EFL) at the second position. Furthermore, in the second mode, the field of view (FOV) of the camera module may be less than approximately 25 degrees, and the F-number may be less than approximately 3.4. When the camera module operates in the third mode, the optical system 1000 may have a TTL (total lens length) value and a BFL3 value at a third position. Additionally, the optical system 1000 may have an FMD3 defined as a third effective focal length (EFL) at the third position. Additionally, in the third mode, the field of view (FOV) of the camera module can be less than approximately 20 degrees, and the F-number can be less than approximately 4.

[0283] like Figure 6 As shown, the relative illumination (RI) in each mode can vary depending on the height of the image sensor, and it can be seen that the relative illumination at the periphery or edge (1.0 field) at the height of the image sensor (field height) is 50% or more. The optical system 1000 can have the following characteristics in the first mode: Figure 8 and Figure 11 The excellent aberration characteristics are shown. In detail, Figure 8 This is a graph showing the diffraction MTF characteristics of the optical system 1000 operating in the first mode (first magnification), and Figure 11 This is a graph showing the aberration characteristics. The diffraction MTF characteristic graph is measured over a spatial frequency range from 0.000 mm to 2.2520 mm, in units of approximately 0.252 mm. In the diffraction MTF graph, T represents the MTF change per millimeter of spatial frequency in the tangential image, and R represents the MTF change per millimeter of spatial frequency in the radial image. Here, the MTF (Modulation Transfer Function) depends on the spatial frequency per millimeter period. Figure 11 The aberration charts, from left to right, represent measurements of spherical aberration (longitudinal spherical aberration), astigmatism curves, and distortion. Figure 8In the graph, the X-axis represents focal length (mm) and distortion (%), and the Y-axis represents the image height. Additionally, the graph for spherical aberration is for light in the wavelength bands of approximately 435 nm, 486 nm, 546 nm, 587 nm, and 656 nm, while the graphs for astigmatism and distortion aberration are for light in the wavelength band of 546 nm. Figure 11 In the aberration diagram, this can be interpreted as the closer each curve is to the Y-axis, the better the aberration correction function. (Reference) Figure 11 As can be seen, the optical system 1000 according to the embodiment has a measurement value close to the Y-axis in almost all areas.

[0284] Table 2 and Figure 3 The items in the above formula of the optical system 1000 of the embodiment include TTL (total lens length) (mm), BFL (back focal length), effective focal length (F) (mm), ImgH (mm), effective length CA (mm), thickness (mm), TTL (mm), TD (mm) (which is the optical axis distance from the first surface S1 to the fourteenth surface S14), the focal lengths F1, F2, F3, F4, F5, F6, F7, F8 (mm) of each of the first to the seventh lenses, the sum of the refractive indices of each lens, the sum of the Abbe numbers of each lens, the sum of the center thicknesses of each lens (mm), the sum of the center distances between adjacent lenses, the effective diameter, the diagonal viewing angle (FOV) (degrees), the edge thickness ET, the focal lengths of the first lens group and the second lens group, the F number, etc.

[0285] [Table 2]

[0286]

[0287]

[0288] Table 3 shows the center distance between the first and second lens groups, the center distance between the second and third lens groups, the center distance DG4 between the eighth lens and the filter, the effective focal length EFL, the entrance pupil size EPD, the optical axis distance TD of the lenses for each mode, and the F-number, viewing angle, and BFL for each mode.

[0289] [Table 3]

[0290]

[0291]

[0292] Tables 4 and 5 show the results of formulas 1 to 55 above in the optical system 1000 of the embodiment. Referring to Table 5, it can be seen that the optical system 1000 satisfies at least one, two or more, or three or more of formulas 1 to 55. In detail, it can be seen that the optical system 1000 according to the embodiment satisfies all formulas 1 to 55. Therefore, the optical system 1000 can have good optical performance and excellent optical characteristics at both the center and periphery of the field of view (FOV).

[0293] [Table 4]

[0294]

[0295]

[0296] [Table 5]

[0297]

[0298]

[0299] The optical system and camera module according to the embodiments may satisfy at least one or two or more of formulas 1 to 30 and / or formulas 31 to 55, or may satisfy all of the formulas.

[0300] Figure 14 This is a diagram illustrating a camera module applied to a mobile terminal according to an embodiment. (Reference) Figure 14 The mobile terminal 1 may include the camera module 10 disclosed in the embodiments on its rear side. As another example, the mobile terminal 1 may include the camera module disclosed in the embodiments on its front side. The camera module 10 may include image capture functionality. Additionally, the camera module 10 may include at least one of autofocus, zoom functionality, and OIS functionality.

[0301] The camera module 10 can process still images or video frames acquired by the image sensor 300 in shooting mode or video call mode. The processed image frames can be displayed on the display unit (not shown) of the mobile terminal 1 and can be stored in a memory (not shown). Additionally, although not shown in the figures, the camera module can also be positioned in front of the mobile terminal 1. For example, the camera module 10 may include a first camera module 10A and a second camera module 10B. In this case, at least one of the first camera module 10A and the second camera module 10B may include the aforementioned optical system 1000. Therefore, the camera module 10 can have a slim structure and can capture objects at various magnifications.

[0302] Mobile terminal 1 may also include an autofocus device 31. The autofocus device 31 may include an autofocus function using a laser. The autofocus device 31 can be used primarily in situations where the autofocus function of the image from camera module 10 is degraded, for example, at close range (10m or less) or in dark environments. The autofocus device 31 may include a light-emitting unit comprising a vertical-cavity surface-emitting laser (VCSEL) semiconductor element and a light-receiving unit, such as a photodiode, that converts light energy into electrical energy. Mobile terminal 1 may also include a flash module 33. The flash module 33 may include a light-emitting element therein that emits light. The flash module 33 may emit light in the visible light wavelength band. For example, the flash module 33 may emit white light or light of a similar color. However, the embodiments are not limited to this, and the flash module 33 may emit light of various colors. The flash module 33 described above can be operated via the camera operation of the mobile terminal or by user control.

[0303] The features, structures, effects, etc., described in the above embodiments are included in at least one embodiment of the present invention, but are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, etc., exemplified in each embodiment can be combined or modified and implemented in other embodiments by those skilled in the art to which the embodiments pertain. Therefore, content related to such combinations and modifications should be interpreted as being included within the scope of the present invention. Although embodiments have been described above, they are merely examples and do not limit the present invention. Those skilled in the art will understand that various modifications and applications not illustrated above are possible without departing from the essential characteristics of these embodiments. For example, each component specifically shown in the embodiments can be modified and implemented. And differences related to such modifications and applications should be interpreted as being included within the scope of the present invention as defined in the appended claims.

Claims

1. An optical system, comprising: The first to third lens groups, each including at least one lens, are arranged along the optical axis from the object side toward the sensor side. The first lens group and the third lens group have negative optical power. The second lens group has positive optical power. The position of the first lens group is fixed. Each of the second lens group and the third lens group is movable along the optical axis according to the operating mode. In the first lens group, the first lens closest to the object has positive optical power and a convex surface on the sensor side. Wherein, the distance of the first lens group along the optical axis is defined as DG1. Wherein, the distance of the second lens group along the optical axis is defined as DG2, and Wherein, the following formula is satisfied: 0.5 <DG1 / DG2<2。 2. The optical system according to claim 1, wherein, The lenses in the first to the third lens groups are made of plastic, and the number of lenses with negative optical power in the first to the third lens groups is greater than the number of lenses with positive optical power.

3. The optical system according to claim 1, wherein, The distance of the second lens group along the optical axis is greater than the distance of each of the first lens group and the third lens group along the optical axis.

4. The optical system according to any one of claims 1 to 3, wherein, The lens with the largest absolute value of focal length among the lenses in the first lens group to the third lens group is located in the first lens group.

5. The optical system according to any one of claims 1 to 3, wherein, The distance of the third lens group along the optical axis is defined as DG3, and the distance from the object-side surface of the lens closest to the object in the first lens group to the upper surface of the image sensor along the optical axis is defined as TTL, and satisfies the following formula: 2 <TTL / (DG2+DG3)<5。 6. The optical system according to any one of claims 1 to 3, wherein, The distance between the lens closest to the image sensor in the third lens group and the image sensor along the optical axis can vary according to the operating mode, and the operating modes of the optical system include wide-angle mode, medium-telephoto mode and telephoto mode.

7. The optical system according to claim 6, wherein, The distance along the optical axis between the object-side surface of the lens closest to the object in the first lens group and the sensor-side surface of the lens closest to the image sensor in the third lens group can vary according to the operating mode, and the distance along the optical axis between the first lens group and the second lens group and the distance along the optical axis between the second lens group and the third lens group is equal to or greater than 0.2 mm and equal to or less than 8 mm.

8. The optical system according to claim 6, wherein, The wide-angle mode is defined as Md1. In the wide-angle mode, the distance along the optical axis between the first lens group and the second lens group is defined as DG12, and the distance along the optical axis between the second lens group and the third lens group is defined as DG23, and satisfies the following formula: 1 <Md1×(DG12 / DG23)<3。 9. The optical system according to claim 6, wherein, The telephoto mode is defined as Md3. In this telephoto mode, the distance between the first lens group and the second lens group is defined as DG12, and the distance between the second lens group and the third lens group is defined as DG23, satisfying the following formula: 0 <Md3×(DG12 / DG23)<0.5。 10. The optical system according to any one of claims 1 to 3, wherein, The maximum distance between adjacent lenses according to the operating mode is defined as Md_CG_Max, and the minimum distance between adjacent lenses according to the operating mode is defined as Md_CG_Min, and the following formula is satisfied: 4 <Md_CG_Max / Md_CG_Min<7。 11. The optical system according to any one of claims 1 to 3, wherein, The number of lenses in the first lens group is greater than the number of lenses in the second lens group, and the absolute value of the focal length of the first lens group is more than twice the absolute value of the focal length of the second lens group.

12. The optical system according to claim 6, wherein, The effective focal length in the wide-angle mode is defined as FMd1, and the focal length of the first lens is defined as F1. The following formula is satisfied: 2 < |F1 / FMd1| < 7.

13. The optical system according to claim 6, wherein, The effective focal length in the telephoto mode is defined as FMd3, and satisfies the following formula: 0 < |F1 / FMd3| < 1.

14. The optical system according to claim 6, wherein, The field of view in wide-angle mode is defined as FOV1, the field of view in medium telephoto mode is defined as FOV2, and the field of view in telephoto mode is defined as FOV3. Satisfy the following formula: 8° <FOV3<FOV2<FOV1<45°。 15. An optical system comprising: The first lens group includes the first lens to the third lens; The second lens group includes the fourth lens and the fifth lens; as well as The third lens group includes lenses six through eight. The first lens group to the third lens group are arranged sequentially along the optical axis from the object toward the sensor. The first lens has positive refractive power and convex object-side and sensor-side surfaces. The third lens has negative refractive power and has a concave object-side surface and a convex sensor-side surface. The fourth lens has positive refractive power and a biconvex shape. The eighth lens has negative refractive power. The second lens group and the third lens group move along the optical axis. The distance between the eighth lens and the image sensor along the optical axis varies depending on the operating mode. Among these, the number of lenses with a refractive index greater than 1.60 among the first to the eighth lenses is greater than the number of lenses with a refractive index less than 1.

60. Wherein, the refractive index of the first lens is defined as Nd1, and Wherein, the following formula is satisfied: 1.65 <Nd1。 16. The optical system according to claim 15, wherein, The first lens group and the third lens group have negative refractive power, and the second lens and the fourth lens have refractive power with opposite signs.

17. The optical system according to claim 15 or 16, wherein, The fourth lens and the eighth lens each have a refractive index of less than 1.

6.

18. The optical system according to claim 15 or 16, wherein, Among the object-side surface and sensor-side surface of each of the first to eighth lenses, the third lens has the largest absolute value of the radius of curvature of its object-side surface.

19. The optical system according to claim 15 or 16, wherein, Among the first to the eighth lenses, the first lens has the largest effective size. The maximum length of the first lens in a first direction orthogonal to the optical axis is different from the maximum length of the first lens in a second direction. The effective size of the largest lens surface among the first to the eighth lenses is defined as CA_Max. Half the diagonal length of the image sensor is defined as ImgH. Wherein, the following formula is satisfied: 1 <CA_Max / ImgH<3。 20. A camera module, comprising: Image sensor; Optical system; as well as A driving member is configured to move at least one of a plurality of lens groups in the optical system along the optical axis. The optical system includes the optical system according to claim 1 or claim 15, and the driving member is configured to move the position of each of the second lens group and the third lens group in the optical axis direction.

Images