Optical system and camera module

Abstract

The optical system according to the present embodiment includes first to third lens groups arranged along an optical axis, wherein the first lens group has a negative (-) refractive power, the second lens group has a positive (+) refractive power, and the third lens group has a negative (-) refractive power, the first lens group is a fixed group, the second lens group and the third lens group are moving groups, and the stroke length of the second lens group is smaller than the stroke length of the third lens group.

Description

Technology Field

[0001] The present invention relates to an optical system for enhanced optical performance and a camera module including the same. Background Technology

[0002] Camera modules perform the function of capturing objects and saving them as images or videos, and are installed in various applications. In particular, camera modules are manufactured in ultra-compact sizes and are applied not only to portable devices such as smartphones, tablet PCs, and laptops, but also to drones and vehicles, providing a wide range of functions.

[0003] 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 aligns the focal length of the lens by automatically adjusting the distance between the image sensor and the imaging lens, and can perform a zooming function of zooming up or zooming out by increasing or decreasing the magnification of a distant object through a zoom lens. Additionally, the camera module employs image stabilization (IS) technology to correct or prevent image shaking caused by camera movement resulting from unstable fixed devices or user movements.

[0004] The most important element for such camera modules to obtain an image is the imaging lens that forms the image. Recently, there has been growing interest in high performance, such as high image quality and high resolution, and research is being conducted on optical systems containing multiple lenses to achieve this.

[0005] For example, research is being conducted using multiple imaging lenses with positive (+) or negative (-) refractive power to implement high-performance optical systems. However, when multiple lenses are included, the entire optical system may become larger, and there are problems in that it is difficult to obtain excellent optical characteristics and aberration characteristics.

[0006] In addition, an optical system containing multiple lenses may have a relatively large height. For example, as the number of lenses increases, the distance from the image sensor to the object surface of the lens adjacent to the object may increase. Accordingly, the overall thickness and length of a device such as a smartphone in which the optical system is installed may increase, and there is a problem that it is difficult to miniaturize.

[0007] Camera modules for close-range imaging have a shorter TTL compared to conventional camera modules. As another example, camera modules for long-range imaging have a longer TTL compared to conventional camera modules. However, since portable terminals have limited installation space for camera modules, it is difficult to mount camera modules for long-range imaging or camera modules capable of adjusting image magnification (zoom camera modules). Therefore, a new optical system capable of solving the aforementioned problems is required. The problem to be solved

[0008] The present embodiment aims to provide a zoom optical system and a camera module with improved optical characteristics.

[0009] This embodiment can provide an optical system that can be implemented in a small and compact manner.

[0010] The present embodiment may provide an optical system in which the lengths of the first direction and the second direction of at least one lens among a plurality of lenses that is adjacent to the object side or adjacent to the outside of the terminal are different. That is, at least one or more of the lenses may provide an optical system in which the lengths of two mutually orthogonal directions are different.

[0011] The present embodiment aims to provide an optical system applicable to a folded camera or teletype having a thin thickness or height. means of solving the problem

[0012] To solve the above technical problem, an optical system according to an embodiment of the present invention includes first to third lens groups arranged along an optical axis, wherein the first lens group has a negative (-) refractive power, the second lens group has a positive (+) refractive power, the third lens group has a negative (-) refractive power, the first lens group is a fixed group, the second lens group and the third lens group are moving groups, and the stroke length of the second lens group is smaller than the stroke length of the third lens group.

[0013] The lens positioned closest to the object side in the second lens group above may have a shape in which both sides are convex at the optical axis.

[0014] The lens positioned closest to the sensor side in the first lens group above may have a shape in which both sides are concave at the optical axis.

[0015] The first lens group above includes a first lens having a positive (+) refractive power, a second lens having a positive (+) refractive power, and a fourth lens having a negative (-) refractive power, and the second lens group above may include a fifth lens having a positive (+) refractive power and a sixth lens having a negative (-) refractive power.

[0016] The above third lens group may include a sixth lens having negative (-) refractive power, a seventh lens having positive (+) refractive power, and an eighth lens having negative (-) refractive power.

[0017] An optical path control member may be disposed on the object side of the first lens group, and an aperture may be disposed between the first lens group and the second lens group.

[0018] The first to third lens groups above may include two or more lenses having different refractive powers.

[0019] The lens positioned closest to the object side in the first lens group above may have a meniscus shape that is convex toward the object side from the optical axis.

[0020] The following condition can be satisfied. <Condition> 0.1 < TD_LG2 / TD_LG3 < 1 (In the above condition, TD_LG2 is the length of the second lens group in the direction of the optical axis, and TD_LG3 is the length of the third lens group in the direction of the optical axis.)

[0021] The following condition can be satisfied. <Condition> 1.7 < n3 < 1.9 (In the above condition, n3 is the refractive index of the third lens.)

[0022] To solve the above technical problem, an optical system according to an embodiment of the present invention includes first to eight lenses arranged along an optical axis, wherein the first lens has a positive (+) refractive power, the second lens has a positive (+) refractive power, the third lens has a negative (-) refractive power, the fourth lens has a positive (+) refractive power, the fifth lens has a negative (-) refractive power, the sixth lens has a negative (-) refractive power, the seventh lens has a positive (+) refractive power, and the eighth lens has a negative (-) refractive power, wherein the third lens has a concave shape on both sides along the optical axis, and the fourth lens has a convex shape on both sides along the optical axis.

[0023] Among the first to eight lenses above, the effective diameter of the first lens may be the largest.

[0024] In the above optical axis, the first lens may have a meniscus shape that is convex toward the object.

[0025] An optical path control member may be disposed on the object side of the first lens, and an aperture may be disposed between the third lens and the fourth lens.

[0026] The following condition can be satisfied. <Condition> 4 < TTL / ImgH < 6 (In the above condition, TTL is the optical axis distance from the vertex of the object side of the first lens to the top plane of the image sensor, and ImgH is the maximum diagonal length of the image sensor.) Effects of the invention

[0027] The optical system and camera module according to the present embodiment have various magnifications and can have excellent optical characteristics when providing various magnifications. Specifically, the embodiment can have various magnifications and provide an autofocus (AF) function for the subject by controlling a set number of lenses, a lens group having refractive power, a plurality of lenses having a set shape and focal length, and a moving distance of a moving lens group.

[0028] In addition, each of the multiple lens groups can correct aberration characteristics or mutually complement aberration characteristics that change due to movement. Accordingly, the optical system according to the embodiment can minimize or prevent changes in chromatic aberration and aberration characteristics that occur when the magnification changes.

[0029] In addition, the effective focal length (EFL) can be controlled by moving only some of the lens groups among multiple lens groups, and the moving distance of the moving lens groups can be minimized. Accordingly, the embodiment can significantly reduce the moving distance of the lens groups when changing the magnification and minimize the power consumption required when moving the lens groups.

[0030] In addition, the optical system according to the present embodiment has enhanced optical characteristics and can have a large BFL (Back focal length), thereby providing an optical system suitable for a folded camera module. Brief explanation of the drawing

[0031] FIG. 1 is a diagram showing the configuration of an optical system according to the present embodiment operating in a first mode. FIG. 2 is a configuration diagram of an optical system according to the present embodiment operating in a third mode. FIG. 3 is a table showing the aspherical coefficients of lenses in an optical system according to the present embodiment. FIG. 4 is a table showing the thickness of each lens of the optical system and the spacing between adjacent lenses according to the present embodiment. FIG. 5 is a table showing the Sag values ​​of the lens surfaces of the first to eighth lenses in the optical system according to the present embodiment. FIG. 6 is a table showing the Slope Angle values ​​of the lens surfaces of the first to eighth lenses in the optical system according to the present embodiment. FIG. 7 is a graph showing data on the aberration characteristics of the optical system according to the present embodiment operating in a third mode. FIG. 8 is a drawing for explaining the D-cut lens of the present invention. FIG. 9 is an example of a portable terminal having an optical system according to the present embodiment. Specific details for implementing the invention

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0033] However, the technical concept of the present invention is not limited to some of the described embodiments but can be implemented in various different forms, and within the scope of the technical concept of the present invention, one or more of the components among the embodiments may be selectively combined or substituted.

[0034] In addition, terms used in this embodiment (including technical and scientific terms) may be interpreted in a sense that is generally understood by those skilled in the art to which this embodiment belongs, unless explicitly and specifically defined otherwise. Terms that are commonly used, such as terms defined in advance, may be interpreted in consideration of their meaning in the context of the relevant technology.

[0035] Furthermore, the terms used in this embodiment are for the purpose of describing the embodiment and are not intended to limit the invention.

[0036] In this specification, the singular form may include the plural form unless specifically stated otherwise in the text, and when described as "at least one of A and B and C (or more than one)," it may include one or more of all combinations that can be formed from A, B, and C.

[0037] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the present embodiment. These terms are used merely to distinguish the components from other components and are not intended to limit the essence, order, or sequence of the components.

[0038] And, where it is stated that a component is 'connected', 'combined', or 'connected' to another component, this may include not only cases where the component is directly 'connected', 'combined', or 'connected' to the other component, but also cases where it is 'connected', 'combined', or 'connected' due to another component located between the component and the other component.

[0039] Furthermore, when described as being formed or placed "above" or "below" each component, "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 placed between the two components. Additionally, when expressed as "above" or "below," it may include the meaning of a downward direction as well as an upward direction relative to a single component.

[0040] In the description of the invention, "object side" may refer to a surface of the lens facing the object side with respect to the optical axis (OA), and "sensor side" may refer to a surface of the lens facing the imaging surface (image sensor) with respect to the optical axis. "Object side" may be the "object side," and "sensor side" may be the "image side." One surface of the lens being convex may refer to a convex shape in the optical axis or paraxial region, and one surface of the lens being concave may refer to a concave shape in the optical axis or paraxial region. The radius of curvature, center thickness, and optical axis spacing between lenses listed in the lens data table may refer to values ​​(unit, mm) in the optical axis. The vertical direction may refer to a direction perpendicular to the optical axis, and the end of the lens or lens surface may refer to the end of the effective area of ​​the lens through which incident light passes. The size of the effective diameter of the lens surface may have a measurement error of up to ±0.4 mm depending on the measurement method, etc. The above paraxial region refers to a very narrow region near the optical axis, and is a region where the distance of light rays from the optical axis (OA) is almost zero. Hereinafter, the term optical axis may include the center of each lens or a very narrow region near the optical axis.

[0041] The optical axis (OA) may refer to the central axis on the path of light where light incident from the second direction (Y-axis direction) is bent into the first direction (X-axis direction) by a prism lens.

[0043] The optical system (1000) according to the present embodiment may include a plurality of lens groups. Specifically, the optical system (1000) may include a plurality of lens groups, each including at least one lens. For example, the optical system (1000) may include a first lens group (LG1), a second lens group (LG2), a third lens group (LG3), and an image sensor (400) that are sequentially arranged from the object side toward the image sensor.

[0044] Each of the first to third lens groups (LG1, LG2, LG3) may have a positive (+) or negative (-) refractive power. The first lens group (LG1) and the second lens group (LG2) may have refractive powers of different signs. For example, the first lens group (LG1) may have a negative (-) refractive power, and the second lens group (LG2) may have a positive (+) refractive power. The second lens group (LG2) and the third lens group (LG3) may have refractive powers of different signs. For example, the second lens group (LG2) may have a positive (+) refractive power, and the second lens group (LG3) may have a negative (-) refractive power.

[0045] At least one of the first to third lens groups (LG1, LG2, LG3) may be provided to be movable in the direction of the optical axis (OA). By setting at least one lens group as a movable group, the stroke can be reduced. Specifically, two or more of the plurality of lens groups (LG1, LG2, LG3) may be provided to be movable, and the remaining lens groups may be fixed. In this embodiment, the first lens group (LG1) may be placed in a fixed position, and the second lens group (LG2) and the third lens group (LG3) may be provided to be movable in the direction of the optical axis (OA).

[0046] The first lens group (LG1) may include a plurality of lenses. The first lens group (LG1) may include three lenses. An optical path control member (111) may be disposed on the object side of the first lens group (LG1).

[0047] The optical system (1000) can reduce the thickness in a first direction (Y-axis direction) perpendicular to the optical axis (OA) direction (X-axis direction) of the optical system (1000) by including an optical path control member (111). If the optical system (1000) does not include an optical path control member (111), a plurality of lenses within an optical device including the optical system (1000) may be arranged to extend in a direction perpendicular to the surface of the optical device.

[0048] Accordingly, multiple lenses have a high height in a direction perpendicular to the surface of the optical device, and it may be difficult to form the thickness of the optical device into an ultra-thin shape. The optical path control member (111) can change light incident in a direction perpendicular to the plane of the optical device into a direction parallel to the surface of the optical device. That is, multiple lenses included in the optical system (1000) can be arranged to extend in a direction parallel to the surface of the optical device, and the optical device can be formed with a thin thickness.

[0049] A driving member (not shown) may be connected to an optical path control member (111). The driving member may include at least one actuator. For example, the driving member may include at least one of a VCM (Voice Coil Motor), a piezoelectric device, a shape memory alloy, or a MEMS device as the actuator. The driving member may move the optical path control member (111) using the driving force of the actuator. For example, the driving member may tilt the optical path control member (111) along a first axis (Y-axis) or a second axis (X-axis). Accordingly, the camera module (1520) can correct shaking.

[0050] It includes a detection unit (not shown) for detecting shaking of the camera module (1520), and the detection unit can detect rotation and position changes applied to the camera module (1520). The detection unit may include at least one of a sensor that detects changes in angular velocity, for example, a gyro sensor, and an acceleration sensor that detects changes in acceleration.

[0051] The camera module (1520) can control the movement of the optical path control member (111) by means of a control signal. Specifically, if shaking occurs in the camera module (1520), information regarding the shaking, such as the degree of rotation and position change of the sensors, can be detected, and correction for the shaking can be performed.

[0052] Accordingly, the camera module (1520) according to the embodiment can effectively correct shaking caused by rotation and shaking caused by changes in position when photographing a subject located at infinity or macro distance. Therefore, the camera module (1520) can have improved optical characteristics.

[0053] A plurality of lenses included in the first lens group (LG1) may have a set spacing. Specifically, the spacing between the plurality of lenses included in the first lens group (LG1) may remain constant and not change in the operation mode described later. For example, the spacing between the first lens (101) and the second lens (102), and the spacing between the second lens (102) and the third lens (103), may remain constant and not change according to the operation mode described later.

[0054] The second lens group (LG2) may include a plurality of lenses. The second lens group (LG2) may include two or more lenses. The plurality of lenses included in the second lens group (LG2) may have a set spacing. Specifically, the spacing between the plurality of lenses included in the second lens group (LG2) may remain constant and not change in the operation mode described later. For example, the spacing between the fourth lens (104) and the fifth lens (105) may remain constant and not change according to the operation mode described later.

[0055] The third lens group (LG3) may include a plurality of lenses. Specifically, the third lens group (LG3) may include three or more lenses having opposite refractive powers. For example, the third lens group (LG3) may include three lenses.

[0056] Multiple lenses included in the third lens group (LG3) may have set spacing. Specifically, the spacing between multiple lenses included in the third lens group (LG3) may remain constant and not change in the operation mode described later. For example, the spacing between the sixth lens (106) and the seventh lens (107), and the spacing between the seventh lens (107) and the eighth lens (108), may remain constant and not change according to the operation mode described later.

[0058] That is, the optical system (1000) may include a plurality of lens groups (LG1, LG2, LG3) and an image sensor (400) arranged sequentially from the object side toward the sensor. Additionally, the optical system (1000) may include a plurality of lenses included in the lens groups (LG1, LG2, LG3), for example, a first lens (101), a second lens (102), a third lens (103), a fourth lens (104), a fifth lens (105), a sixth lens (106), a seventh lens (107), and an eighth lens (108).

[0059] The first lens group (LG1) may include a first lens (101), a second lens (102), and a third lens (103). The second lens group (LG2) may include a fourth lens (104) and a fifth lens (105). The third lens group (LG3) may include a sixth lens (106), a seventh lens (107), and an eighth lens (108). The first lenses (101) through the eighth lenses (108) and the image sensor (400) may be arranged sequentially from the object side of the optical system (1000) toward the sensor.

[0060] Each of the plurality of lenses may include an effective region and an ineffective region. The effective region may be a region through which light incident on each of the first lens (101) to the eighth lens (108) passes. That is, the effective region may be a region where the incident light is refracted to realize optical characteristics.

[0061] The non-effective region may be positioned around the perimeter of the effective region. The non-effective region may be an area where light is not incident. In other words, the non-effective region may be an area unrelated to optical properties. Additionally, the non-effective region may be an area fixed to a barrel (not shown) that accommodates the lens.

[0062] Referring to FIG. 8, at least one of the first lens (101) to the eighth lens (108) in the optical system (1000) according to the present embodiment may have a D-cut technique applied. When the D-cut technique is applied, the height of the entire optical system may be reduced by cutting off a portion of the lens effective diameter or rib. Here, the height of the entire optical system may refer to the length in a direction perpendicular to the optical axis, rather than the TTL. The D-cut lens may have a non-circular shape, and the length (A) in the first direction (Y-axis direction) and the length (B) in the second direction (X-axis direction) may be different.

[0064] The image sensor (400) can detect light. The image sensor (400) can detect light that has passed through a plurality of lenses, for example, the first lens (101) to the eighth lens (108) in sequence. The image sensor (400) may include a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS), etc.

[0065] The optical system (1000) may further include a filter (500). The filter (500) may be placed between a plurality of lenses and an image sensor (400). The filter (500) may be placed between the image sensor (400) and the third lens group (LG3) that is closest to the image sensor (400) among a plurality of lens groups (LG1, LG2, LG3). For example, the filter (500) may be placed between the image sensor (400) and the last lens of the fifth lens group (LG5) that is closest to the image sensor (400) among the plurality of lenses.

[0066] The filter (500) may include at least one of an optical filter, such as an infrared filter or a cover glass. The filter (500) may pass light of a set wavelength band and filter light of a different wavelength band. If the filter (500) includes an infrared filter, it may block radiant heat emitted from external light from being transmitted to the image sensor (400). Additionally, the filter (500) may transmit visible light and reflect infrared light.

[0067] The optical system (1000) may include an aperture (not shown). The aperture can control the amount of light incident on the optical system (1000). The aperture may be placed between two adjacent lens groups. The aperture may be placed between a first lens group (LG1) and a second lens group (LG2). The aperture may be placed on the sensor side of a third lens (103) that is closest to the sensor side in the first lens group (LG1). The aperture may be placed on the object side of a fourth lens (104) that is closest to the object side in the second lens group (LG2).

[0068] The aperture may be positioned in front of the first lens (101) or between two selected lenses among the first lens (101) to the eighth lens (108). For example, the aperture may be positioned between the third lens (1043) and the fourth lens (104). Additionally, at least one of the first lens (101) to the eighth lens (108) may function as an aperture. For example, the object side or sensor side of one of the selected lenses among the first lens (101) to the eighth lens (108) may function as an aperture that controls the amount of light.

[0070] The optical system according to the present embodiment of the invention will be described.

[0071] FIG. 1 is a configuration diagram of an optical system according to the present embodiment operating in a first mode, FIG. 2 is a configuration diagram of an optical system according to the present embodiment operating in a third mode, FIG. 3 is a table showing the aspherical coefficients of the lenses in the optical system according to the present embodiment, FIG. 4 is a table showing the thickness of each lens and the spacing between adjacent lenses in the optical system according to the present embodiment, FIG. 5 is a table showing the Sag values ​​of the lens surfaces of the first to eighth lenses in the optical system according to the present embodiment, FIG. 6 is a table showing the Slope Angle values ​​of the lens surfaces of the first to eighth lenses in the optical system according to the present embodiment, and FIG. 7 is a graph showing data on the aberration characteristics of the optical system according to the present embodiment operating in a third mode.

[0072] Referring to FIGS. 1 and 2, the optical system (1000) includes a lens portion, and the lens portion may include a first lens (101) to an eighth lens (108). The first to eighth lenses (101-108) may be arranged sequentially along the optical axis (OA) of the optical system (1000). Light corresponding to information about an object may pass through the first to eighth lenses (101-108) and a filter (500) and be incident on an image sensor (400).

[0073] The optical path control member (111) can change the path of light incident from the outside. The optical path control member (111) can be positioned closest to the object side. The optical path control member (111) can be positioned on the object side of the first lens (101). The optical path control member (111) may include a reflector and a prism.

[0074] The optical path control member (111) can rotate the optical path by 90°. The optical path control member (111) includes an incident surface (P1) into which light is incident, a reflective surface (RS1) that reflects the incident light, and an exit surface (P2) that emits the reflected light. The reflective surface (RS1) has an inclination angle of 45° and reflects the main beam of the incident light by 90°, thereby serving to reflect the incident light to the third lens (103). The optical path control member (111) can change the path of the light to the first direction (X-axis direction) by reflecting the light incident in the second direction (Y-axis direction).

[0075] The first lens (101) may be positioned closest to the object side. The first lens (101) may be positioned furthest from the sensor side. The first lens (101) may have a positive (+) refractive power at the optical axis (OA). The first lens (101) may include a plastic material or a glass material, and may be, for example, a plastic material.

[0076] With respect to the optical axis (OA), the first surface (S1) on the object side of the first lens (101) may be convex, and the second surface (S2) on the sensor side may be concave. The first lens (101) may have a meniscus shape with the object side being convex. The first lens (101) may have a meniscus shape with the sensor side being concave. The first lens (101) may have an aspherical surface. The aspherical coefficients of the first and second surfaces (S1, S2) may be provided as L1S1 and L1S2 of FIG. 3. At least one or both of the first surface (S1) and the second surface (S2) of the first lens (101) may be provided without a critical point from the optical axis to the end of the effective area.

[0077] The second lens (102) may be positioned second from the object side. The second lens (102) may be positioned seventh from the sensor side. The second lens (102) may be positioned between the first lens (101) and the third lens (103). The second lens (102) may have a positive (+) refractive power. The second lens (102) may include plastic or glass material. For example, the second lens (102) may be provided with plastic material.

[0078] With respect to the optical axis, the object-side third surface (S3) of the second lens (102) may be convex, and the sensor-side fourth surface (S4) may be convex. The second lens (102) may have a shape with both sides convex. The second lens (102) may have an aspherical surface. The aspherical coefficients of the third surface (S3) and the fourth surface (S4) may be provided as L2S1 and L2S2 of FIG. 2. At least one or both of the third surface (S3) and the fourth surface (S4) of the second lens (102) may be provided without a threshold point from the optical axis to the end of the effective area.

[0079] The third lens (103) may be positioned as the third lens from the object side. The third lens (103) may be positioned as the sixth lens from the sensor side. The third lens (103) may be positioned between the second lens (102) and the fourth lens (104). The third lens (103) may have a negative (-) refractive power at the optical axis (OA). The third lens (103) may include plastic or glass material.

[0080] For example, the third lens (103) may be provided with a glass mold material. A glass mold lens may be made of glass material. A glass mold lens may be manufactured by placing an optical glass ingot inside a mold that will have an aspherical shape and through a heating and compression process. A lens made of glass mold material can be designed with a wide range of refractive indices, which is advantageous for correcting aberrations, and can reduce the TTL and stroke length of the moving group of the optical system (1000).

[0081] With respect to the optical axis, the object-side fifth surface (S5) of the third lens (103) may be concave, and the sensor-side sixth surface (S6) may be concave. The third lens (103) may have a shape in which both sides are concave on the optical axis (OA). The third lens (103) may have an aspherical surface. The aspherical coefficients of the fifth surface (S5) and the sixth surface (S6) may be provided as L3S1 and L3S2 of FIG. 3. At least one or both of the fifth surface (S5) and the sixth surface (S6) of the third lens (103) may be provided without a threshold point from the optical axis to the end of the effective area.

[0082] The aperture (Stop) can be positioned between the sensor-side lens of the first lens group (LG1) and the object-side lens of the second lens group (LG2). The aperture (Stop) can be positioned between the third lens (103) and the fourth lens (104). The aperture can reduce TTL within the angle of view range, and the optical system can be miniaturized. Accordingly, a decrease in yield by weight of the optical system can be prevented, and production efficiency can be improved. In addition, the optical system can be miniaturized by reducing TTL within a diagonal angle of view (FOV) of 10 to 30 degrees.

[0083] The fourth lens (104) may be positioned as the fourth lens from the object side. The fourth lens (104) may be positioned as the fifth lens from the sensor side. The fourth lens (104) may be positioned between the third lens (103) and the fifth lens (105). The fourth lens (104) may have a positive (+) refractive power. The fourth lens (104) may include plastic or glass materials. For example, the fourth lens (104) may be provided with a plastic material.

[0084] With respect to the optical axis, the object-side 7th surface (S7) of the 4th lens (104) may be convex, and the sensor-side 8th surface (S8) may be convex. The 4th lens (104) may have a shape with both sides convex. The 4th lens (104) may have an aspherical surface. The aspherical coefficients of the 7th surface (S7) and the 8th surface (S8) may be provided as L4S1 and L4S2 of FIG. 3. At least one or both of the 7th surface (S7) and the 8th surface (S8) of the 4th lens (104) may be provided without a threshold point from the optical axis to the end of the effective area.

[0085] The fifth lens (105) may be positioned as the fifth lens from the object side. The fifth lens (105) may be positioned as the fourth lens from the sensor side. The fifth lens (105) may be positioned between the fourth lens (104) and the sixth lens (106). The fifth lens (105) may have a positive (+) or negative (-) refractive power at the optical axis (OA). The fifth lens (105) may have a negative (-) refractive power. The fifth lens (105) may include plastic or glass materials. For example, the fifth lens (105) may be provided with a plastic material.

[0086] With respect to the optical axis (OA), the fifth lens (105) may have a concave ninth surface (S9) on the object side and a convex tenth surface (S10) on the sensor side. The fifth lens (105) may have a meniscus shape with the object side being concave. The fifth lens (105) may have a meniscus shape with the sensor side being convex. The fifth lens (105) may have an aspherical surface. The aspherical coefficients of the ninth surface (S9) and the tenth surface (S10) may be provided as L5S1 and L5S2 of FIG. 3. At least one or both of the ninth surface (S9) and the tenth surface (S10) of the fifth lens (105) may be provided without a threshold point from the optical axis to the end of the effective area.

[0087] The sixth lens (106) may be positioned as the sixth lens from the object side. The sixth lens (106) may be positioned as the third lens from the sensor side. The sixth lens (106) may be positioned between the fifth lens (105) and the seventh lens (107). The sixth lens (106) may have a positive (+) or negative (-) refractive power at the optical axis (OA). The sixth lens (106) may have a negative (-) refractive power. The sixth lens (106) may include plastic or glass materials. For example, the sixth lens (106) may be provided with a plastic material.

[0088] With respect to the optical axis (OA), the 6th lens (106) may have an object-side 11th surface (S11) that is concave and a sensor-side 12th surface (S12) that is concave. The 6th lens (106) may have a shape with both sides concave. The 6th lens (106) may have an aspherical surface. The aspherical coefficients of the 11th surface (S11) and the 12th surface (S12) may be provided as L6S1 and L6S2 of FIG. 3. At least one or both of the 11th surface (S11) and the 12th surface (S12) of the 6th lens (106) may be provided without a threshold point from the optical axis to the end of the effective area.

[0089] The seventh lens (107) may be positioned as the seventh lens from the object side. The seventh lens (107) may be positioned as the second lens from the sensor side. The seventh lens (107) may be positioned between the sixth lens (106) and the eighth lens (108). The seventh lens (107) may have a positive (+) or negative (-) refractive power at the optical axis (OA). The seventh lens (107) may have a positive (+) refractive power. The seventh lens (107) may include plastic or glass materials. For example, the seventh lens (107) may be provided with a plastic material.

[0090] With respect to the optical axis (OA), the 7th lens (107) may have a concave 13th surface (S13) on the object side and a convex 14th surface (S14) on the sensor side. The 7th lens (107) may have a meniscus shape with the object side being concave. The 7th lens (107) may have a meniscus shape with the sensor side being convex. The 7th lens (107) may have an aspherical surface. The aspherical coefficients of the 13th surface (S13) and the 14th surface (S14) may be provided as L7S1 and L7S2 of FIG. 3. At least one or both of the 13th surface (S13) and the 14th surface (S14) of the 7th lens (107) may be provided without a critical point from the optical axis to the end of the effective area.

[0091] The eighth lens (108) may be positioned closest to the sensor side. The eighth lens (108) may be positioned furthest from the object side. The eighth lens (108) may have negative (-) refractive power. The eighth lens (108) may include plastic or glass material. For example, the eighth lens (108) may be provided with plastic material.

[0092] With respect to the optical axis (OA), the 8th lens (108) may have a convex shape on the object-side 15th surface (S15) and a concave shape on the sensor-side 16th surface (S16). The 8th lens (108) may have a meniscus shape that is convex toward the object side. The 8th lens (108) may have a meniscus shape that is concave toward the sensor side. The 8th lens (108) may have an aspherical shape. The aspherical coefficients of the 15th surface (S15) and the 16th surface (S16) may be provided as L8S1 and L8S2 of FIG. 3.

[0093] The 15th surface (S15) of the 8th lens (108) may be provided without a critical point from the optical axis to the end of the effective area. The 16th surface (S16) of the 8th lens (108) may have a critical point from the optical axis to the end of the effective area. If the 16th surface (S16) has a critical point, it may be located in the range of 35% to 55% of the effective radius from the optical axis, preferably in the range of 40% to 50%. The critical point of the 16th surface (S16) may be located in the range of 1.0 mm to 2.5 mm from the optical axis, preferably in the range of 1.5 mm to 2.0 mm. The critical point of the 16th surface (S16) is a point where the sign of the slope value with respect to the optical axis and the direction perpendicular to the optical axis changes from positive (+) to negative (-) or from negative (-) to positive (+), and may mean a point where the slope value is 0. In addition, the critical point of the 16th surface (S16) may be a point where the slope value of the tangent line passing through the lens surface increases and then decreases, or a point where it decreases and then increases.

[0095] Lens Surface Radius Thickness nd vd SemiAperture Prism P1 Infinity 8.800 1.855 　 8.200 　 P2 Infinity 0.650 　 　 8.817 1 S1 8.744 2.763 1.547 56.332 8.200 　 S2 42.786 1.445 　 　 7.623 2 S3 59.848 0.834 1.669 20.348 7.047 　 S4 -79.016 1.353 　 　 6.890 3 S5 -16.074 0.400 1.811 40.730 6.248 　 S6 8.891 가변(D1) 　 　 6.182 4 S7 5.747 2.471 1.547 56.332 6.720 　 S8 -8.795 0.030 　 　 6.631 5 S9 -11.186 2.900 1.621 25.950 6.546 　 S10 -67.577 가변(D2) 　 　 5.945 6 S11 -572.557 2.819 1.679 19.239 5.650 　 S12 13.365 1.198 　 　 5.394 7 S13 -18.226 2.396 1.679 19.239 5.547 　 S14 -7.158 0.150 　 　 6.155 8 S15 160.636 0.749 1.547 56.332 6.108 　 S16 8.375 가변(D3) 　 　 6.381 Filter 　 Infinity 0.210 1.519 　 6.971 　 　 Infinity 0.712 　 　 6.984 Image 　 0.000 0.000 　 　 7.057

[0097] Table 1 shows the surface number, radius of curvature, thickness of the center of each lens or distance between lens surfaces, index, nd, Abbe number (Abbe,vd), effective radius (Semi Aperture), and focal length of the lens according to the present embodiment of the present invention. At this time, the units of the radius of curvature and the thickness or distance may be mm.

[0099] wide middle tele D1 8.000 3.913 0.713 D2 3.451 2.013 2.138 D3 3.117 8.641 11.718

[0101] Table 2 relates to the spacing between lenses (D1, D2, D3) that varies when operating in any one of the first to third modes in the optical system according to the present embodiment of the invention. Here, the first mode may mean a wide angle, the second mode may mean a middle angle, and the third mode may mean a telephoto angle. The wide angle may be referred to as a wide angle, and the telephoto angle may be referred to as a telephoto.

[0102] In the optical system according to the present embodiment of the invention, the distance between adjacent lens groups may change during the process of changing the magnification from a first mode to a third mode. The first lens group (LG1) is fixed, and only the second and third lens groups (LG2, LG3) may move. The first lens group (LG1) may be a fixed group, and the second and third lens groups (LG2, LG3) may be moving groups.

[0103] The second lens group (LG2) is a moving group that zooms to change the magnification, and the third lens group (LG3) may be a moving group for AF correction functions. For zoom magnification, the fourth lens (104), which is positioned closest to the object side in the second lens group (LG2), may be convex on both sides of the optical axis, have the smallest focal length, and have the largest refractive power. The combined refractive power of the first lens group (LG1) must be negative (-) so that light can be spread well to the second lens group (LG2) that performs the zoom magnification function, thereby enabling the implementation of an appropriate zoom magnification in the optical system (1000).

[0104] When operating from the first mode to the second mode, the distance (D1) between the first lens group (LG1) and the second lens group (LG2) is reduced, the distance (D2) between the second lens group (LG2) and the third lens group (LG3) is reduced, and the distance (D3) between the third lens group (LG3) and the filter (500) can be increased.

[0105] When operating from the second mode to the third mode, the distance (D1) between the first lens group (LG1) and the second lens group (LG2) decreases, the distance (D2) between the second lens group (LG2) and the third lens group (LG3) increases, and the distance (D3) between the third lens group (LG3) and the filter (500) can increase.

[0106] When operating from the first mode to the third mode, the distance (D1) between the first lens group (LG1) and the second lens group (LG2) is reduced, the distance (D2) between the second lens group (LG2) and the third lens group (LG3) is reduced, and the distance (D3) between the third lens group (LG3) and the filter (500) can be increased.

[0107] The stroke length of the second lens group (LG2) can be 5 mm to 10 mm, and preferably about 7.287 mm. The stroke length of the third lens group (LG3) can be 5 mm to 10 mm, and preferably about 8.600 mm.

[0108] The stroke length of the second lens group (LG2) may be smaller than the stroke length of the third lens group (LG3). The second lens group (LG2) and the third lens group (LG3) may have different moving speeds. The moving speed of the second lens group (LG2) may be smaller than the moving speed of the third lens group (LG3). In this embodiment, the magnification of the wide-angle end and the telephoto end may satisfy a range of 2 to 4 times, and may satisfy a magnification of approximately 2.807 times.

[0110] EFL(f)_wide 19.640 BFL_wide 4.040 EFL(f)_mid 29.239 BFL_mid 9.564 EFL(f)_tele 39.259 BFL_tele 12.640 EPD_wide 6.960 SD_wide 16.165 EPD_mid 8.002 SD_mid 14.727 EPD_tele 8.200 SD_tele 14.851 Fno_wide 2.822 FOV_wide 20.611 Fno_mid 3.654 FOV_mid 13.855 Fno_tele 4.788 FOV_tele 10.291 f1 19.539 ET1 1.883 f2 51.035 ET2 0.683 f3 -7.010 ET3 1.055 f4 6.763 ET4 1.044 f5 -22.034 ET5 0.170 f6 -19.183 ET6 3.423 f7 15.952 ET7 0.617 f8 -16.188 ET8 0.335 f_LG1 -32.596 L_CT_max 2.900 f_LG2 9.333 L_CT_min 0.400 f_LG3 -19.493 L_CT_aver 1.917 CA_Max 7.912 TD_LG1 6.796 CA_Min 5.522 TD_LG2 5.401 CA_Aver 6.454 TD_LG3 7.313 LG2_stroke 7.287 ΣCT 15.334 LG3_stroke 8.600 ImgH 7.056 TTL 35.000

[0112] Table 3 relates to the items of the mathematical formulas described above in the optical system (1000) of the present embodiment, and includes the effective focal length (F) (mm), BFL (Back Focal Length) (mm), EPD (mm), SD (mm) which is the optical axis distance from the aperture (STOP) to the 16th plane (S16), Fno, FOV (degree), the focal lengths (f1-f8) (mm) of the first to eighth lenses (101-108), the edge thickness (ET1-ET8), the focal lengths (f_LG1, f_LG2, f_LG3) (mm) of the first to third lens groups (LG1, LG2, LG3), the stroke length (LG2_stroke) of the second lens group (LG2), the stroke length (G3_stroke) of the third lens group (LG3), and the entire optical system (1000). This concerns the optical axis distances TTL (mm), ImgH (mm), maximum effective diameter (CA_Max), minimum effective diameter (CA_Min), average effective diameter (CA_Aver), maximum center thickness (L_CT_max), minimum center thickness (L_CT_min), and average center thickness (L_CT_aver) among the first to eighth lenses (101-108), and the lengths of each lens group in the optical axis direction (TD_LG1, TD_LG2, TD_LG3), etc.

[0114] The center thickness of the first to eighth lenses (101 to 108) is denoted as CT1 to CT8, the edge thickness at the end of the effective area of ​​each lens is denoted as ET1 to ET8, the center gap between two adjacent lenses is denoted as CG1 to CG7, and the edge gap between the edges of each lens is denoted as EG1 to EG7. BFL (Back focal length) is the optical axis distance from the image sensor (400) to the center of the last lens. TTL is the optical axis distance from the center of the first surface (S1) of the first lens (101) to the top surface of the image sensor (400). The description of the relationship between the optical path control members (111) is partially omitted below.

[0116] When comparing the absolute values ​​of the radius of curvature of each lens, the radius of curvature of the eleventh surface (S11) of the sixth lens (106) at the optical axis (OA) may be the maximum among the lenses, and the radius of curvature of the seventh surface (S7) of the fourth lens (104) may be the minimum among the lenses. The absolute value of the radius of curvature of the first surface (S1) of the first lens (101) may be smaller than the absolute value of the radius of curvature of the second surface (S2). The absolute value of the radius of curvature of the third surface (S3) of the second lens (102) may be smaller than the absolute value of the radius of curvature of the fourth surface (S4). The absolute value of the radius of curvature of the fifth surface (S5) of the third lens (103) may be larger than the absolute value of the radius of curvature of the sixth surface (S6). The absolute value of the radius of curvature of the 7th surface (S7) of the 4th lens (104) may be smaller than the absolute value of the radius of curvature of the 8th surface (S8). The absolute value of the radius of curvature of the 9th surface (S9) of the 5th lens (105) may be smaller than the absolute value of the radius of curvature of the 10th surface (S10). The absolute value of the radius of curvature of the 11th surface (S11) of the 6th lens (106) may be larger than the absolute value of the radius of curvature of the 12th surface (S12). The absolute value of the radius of curvature of the 13th surface (S13) of the 7th lens (107) may be larger than the absolute value of the radius of curvature of the 14th surface (S14). The absolute value of the radius of curvature of the 15th surface (S15) of the 8th lens (108) may be larger than the absolute value of the radius of curvature of the 16th surface (S16).

[0117] The ratio of the radius of curvature of each lens can satisfy the following conditions.

[0118] Condition 1: 0.1 < |L1R1 / L1R2| < 0.5

[0119] Condition 2: 0.5 < |L2R1 / L2R2| < 1

[0120] Condition 3: 1.5 < |L3R1 / L3R2| < 2

[0121] Condition 4: 0.5 < |L4R1 / L4R2| < 1

[0122] Condition 5: 0.1 < |L5R1 / L5R2| < 0.5

[0123] Condition 6: 30 < |L6R1 / L6R2| < 50

[0124] Condition 7: 2.5 < |L7R1 / L7R2| < 3

[0125] Condition 8: 15 < |L8R1 / L8R2| < 20

[0127] When describing the center thickness of the lenses based on the optical axis, the center thickness (CT5) of the fifth lens (105) is the largest among the lenses, and the center thickness (CT3) of the third lens (103) is the smallest among the lenses. The difference between the maximum center thickness and the minimum center thickness among the lenses may be in the range of 2 mm or more and 3 mm or less.

[0128] The center thickness of each lens can satisfy any one of the following conditions.

[0129] Condition 1: CT5, CT6 > CT1 > CT2, CT3, CT4, CT7, CT8

[0130] Condition 2: CT1, CT4, CT5, CT6, CT7 > CT2 > CT3, CT8

[0131] Condition 3: CT1, CT2, CT4, CT5, CT6, CT7, CT8 > CT3

[0132] Condition 4: CT1, CT5, CT6 > CT4 > CT2, CT3, CT7, CT8

[0133] Condition 5: CT5 > CT1, CT2, CT3, CT4, CT6, CT7, CT8

[0134] Condition 6: CT5 > CT6 > CT1, CT2, CT3, CT4, CT7, CT8

[0135] Condition 7: CT1, CT4, CT5, CT6 > CT7 > CT2, CT3, CT8

[0136] Condition 8: CT1, CT2, CT4, CT5, CT6, CT7 > CT8 > CT3

[0138] When zooming, the distance between the first lens (101) and the second lens (102) (CG1), the distance between the second lens (102) and the third lens (103) (CG2), the distance between the fourth lens (104) and the fifth lens (105) (CG4), the distance between the sixth lens (106) and the seventh lens (107) (CG6), and the distance between the seventh lens (107) and the eighth lens (108) (CG7) do not change, while the distance between the third lens (103) and the fourth lens (104) (CG3) and the distance between the fifth lens (105) and the sixth lens (106) (CG5) may change. Among the center distances between the lenses that do not change, the center distance between the first lens (101) and the second lens (102) (CG1) is maximum, and the center distance between the fourth lens (104) and the fifth lens (105) (CG4) may be minimum. The difference between the maximum center gap and the minimum center gap among the spaced-out lens gaps may be 1 mm or more, for example, in the range of 1 mm to 1.5 mm.

[0139] The center spacing between each lens can satisfy the following conditions.

[0140] Condition 1: CG1 > CG2, CG4, CG6, CG7

[0141] Condition 2: CG1 > CG2 > CG41, CG6, CG7

[0142] Condition 3: CG1, CG2, CG6, CG7 > CG4

[0143] Condition 4: CG1, CG2 > CG6 > CG4, CG7

[0144] Condition 5: CG1, CG2, CG6 > CG7 > CG4

[0146] Regarding the effective aperture, the lens having the maximum effective aperture may be the first lens (101). Here, the effective aperture is the average of the effective aperture on the object side and the effective aperture on the sensor side of each lens. The lens surface having the maximum effective aperture may be the first surface (S1) of the first lens (101). The lens having the minimum effective aperture may be the sixth lens (106). The lens surface having the minimum effective aperture may be the twelfth surface (S12) of the sixth lens (106).

[0147] The effective diameter of each lens can satisfy any one of the following conditions.

[0148] Condition 1: CA_L1 > CA_L2, CA_L3, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8

[0149] Condition 2: CA_L1 > CA_L2 > CA_L3, CA_L4, CA_L5, CA_L6, CA_L7, CA_L8

[0150] Condition 3: CA_L1, CA_L2, CA_L4, CA_L5, CA_L8 > CA_L3 > CA_L6, CA_L7

[0151] Condition 4: CA_L1, CA_L2 > CA_L4 > CA_L3, CA_L5, CA_L6, CA_L7, CA_L8

[0152] Condition 5: CA_L1, CA_L2, CA_L4 > CA_L5 > CA_L3, CA_L6, CA_L7, CA_L8

[0153] Condition 6: CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L7, CA_L8 > CA_L6

[0154] Condition 7: CA_L1, CA_L2, CA_L3, CA_L4, CA_L5, CA_L8 > CA_L7 > CA_L6

[0155] Condition 8: CA_L1, CA_L2, CA_L4, CA_L5 > CA_L8 > CA_L3, CA_L6, CA_L7

[0157] Regarding the refractive index, the refractive index of the third lens (103) is the maximum among the lenses and may be greater than 1.7, for example, greater than 1.8. The refractive indices of the first lens (101), the fourth lens (104), and the eighth lens (108) are the minimum among the lenses and may be less than 1.6, for example, less than 1.55. The difference between the maximum and minimum refractive indices may be 0.2 or greater.

[0158] The refractive index of each lens can satisfy any one of the following conditions.

[0159] Condition 1: n2, n3, n5, n6, n7 > n1 = n4 = n8

[0160] Condition 2: n3, n6, n7 > n2 > n1, n4, n5, n8

[0161] Condition 3: n3 > n1, n2, n4, n5, n6, n7, n8

[0162] Condition 4: n2, n3, n6, n7 > n5 > n1, n4, n8

[0163] Condition 5: n3 > n6 = n7 > n1, n2, n4, n5, n8

[0165] When comparing the Abbe numbers, the Abbe numbers of the first lens (101), the fourth lens (104), and the eighth lens (108) are the maximum among the lenses and may be 50 or more. The Abbe numbers of the sixth lens (106) and the seventh lens (107) are the minimum among the lenses and may be 20 or less. The difference between the maximum refractive index and the minimum Abbe number may be 30 or more.

[0166] The Abbe number of each lens can satisfy any one of the following conditions.

[0167] Condition 1: v1 = v4 = v8 > v3, v5, v2, v7, v6

[0168] Condition 2: v1, v3, v4, v5, v8 > v2 > v6, v7

[0169] Condition 3: v1, v4, v8 > v3 > v2, v5, v6, v7

[0170] Condition 4: v1, v3, v4, v8 > v5 > v2, v6, v7

[0171] Condition 5: v1, v2, v3, v4, v5, v8 > v6 = v7

[0173] The focal lengths (F1, F2, F4, F7) of the 1st, 2nd, 4th, and 7th lenses (101, 102, 104, 107) may have a positive (+) sign. The 1st, 2nd, 4th, and 7th lenses (101, 102, 104, 107) may have a positive (+) refractive power. The focal lengths (F3, F5, F6, F8) of the 3rd, 5th, 6th, and 8th lenses (103, 105, 106, 108) may have a negative (-) sign. The 3rd, 5th, 6th, and 8th lenses (103, 105, 106, 108) may have a negative (-) refractive power.

[0174] When comparing the absolute values ​​of the focal lengths, the focal length of the second lens (102) is the maximum among the lenses and may be 40 or more and 60 or less. The focal length of the fourth lens (104) is the minimum among the lenses, and the absolute value of the focal length of the fourth lens (104) may be 5 or more and 8 or less.

[0175] The absolute value of the focal length of each lens can satisfy any one of the following conditions.

[0176] Condition 1: |f2|, |f5| > |f1| > |f3|, |f4|, |f6|, |f7|, |f8|

[0177] Condition 2: |f2| > |f1|, |f3|, |f4|, |f5|, |f6|, |f7|, |f8|

[0178] Condition 3: |f1|, |f2|, |f5|, |f6|, |f7|, |f8| > |f3| > |f4|

[0179] Condition 4: |f1|, |f2|, |f3|, |f5|, |f6|, |f7|, |f8|> |f4|

[0180] Condition 5: |f2| > |f5| > |f1|, |f3|, |f4|, |f6|, |f7|, |f8|

[0181] Condition 6: |f1|, |f2|, |f5| > |f6| > |f3|, |f4|, |f7|, |f8|

[0182] Condition 7: |f1|, |f2|, |f5|, |f6|, |f8| > |f7| > |f3|, |f4|

[0183] Condition 8: |f1|, |f2|, |f5|, |f6| > |f8| > |f3|, |f4|, |f7|

[0185] The combined focal length (f_LG1) of the first lens group (LG1) can have a negative (-) sign. The first lens group (LG1) can have a negative (-) combined refractive power. The combined focal length (f_LG2) of the second lens group (LG2) can have a positive (+) sign. The second lens group (LG2) can have a positive (+) combined refractive power. The combined focal length (f_LG3) of the third lens group (LG3) can have a negative (-) sign. The third lens group (LG3) can have a negative (-) combined refractive power. Through this, light incident from the object side can move away from the optical axis direction and then converge back towards the optical axis direction, thereby forming a stable optical path.

[0186] When comparing the absolute values ​​of the combined focal lengths of the first to third lens groups (LG1, LG2, LG3), the combined focal length of the first lens group (LG1) may be the largest, and the combined focal length of the second lens group (LG2) may be the smallest. The relationship between the combined focal lengths of the first to third lens groups (LG1, LG2, LG3) may satisfy |f_LG1| > |f_LG3| > |f_LG2|.

[0188] The thickness (T1) of the first lens (101) may be minimum at the edge and maximum at the center, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T2) of the second lens (102) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T3) of the third lens (103) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 2.5 to 3 times the minimum thickness. The thickness (T4) of the fourth lens (104) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness. The thickness (T5) of the fifth lens (105) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 15 to 20 times the minimum thickness. The thickness (T6) of the sixth lens (106) may be minimum at the center and maximum at the edge, and the maximum thickness is in the range of 1 to 1.5 times the minimum thickness. The thickness (T7) of the seventh lens (107) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 3.5 to 4 times the minimum thickness. The thickness (T8) of the eighth lens (108) may be maximum at the center and minimum at the edge, and the maximum thickness is in the range of 2 to 2.5 times the minimum thickness.

[0190] The thickness of each lens can satisfy any one of the following conditions.

[0191] Condition 1: 1 < CT1 / ET1 < 1.5, 0.5 < ET1 / CT1 < 1

[0192] Condition 2: 1 < CT2 / ET2 < 1.5, 0.5 < ET2 / CT2 < 1

[0193] Condition 3: 0.1 < CT3 / ET3 < 0.5, 2.5 < ET3 / CT3 < 3

[0194] Condition 4: 2 < CT4 / ET4 < 2.5, 0.1 < ET4 / CT4 < 0.5

[0195] Condition 5: 15 < CT5 / ET5 < 20, 0.01 < ET5 / CT5 < 0.1

[0196] Condition 6: 0.5 < CT6 / ET6 < 1, 1 < ET6 / CT6 < 1.5

[0197] Condition 7: 3.5 < CT7 / ET7 < 4, 0.1 < ET7 / CT7 < 0.5

[0198] Condition 8: 2 < CT8 / ET8 < 2.5, 0.1 < ET8 / CT8 < 0.5

[0199] Condition 9: 1.5 < ΣCT / ΣET < 2, 0.5 < ΣET / ΣCT < 1

[0201] Among the gaps (G1-G8) between the lenses, the gap (G1) between the first and second lenses (101, 102) may have a maximum center and a minimum edge. The gap (G2) between the second and third lenses (102, 103) may have a minimum edge and a maximum center. The gap (G3) between the third and fourth lenses (103, 104) may have a maximum edge and a minimum center. The gap (G4) between the fourth and fifth lenses (104, 105) may have a maximum edge and a minimum center. The fifth gap (G5) between the fifth and sixth lenses (105, 106) may have a minimum center and a maximum edge. The sixth gap (G6) between the sixth and seventh lenses (106, 107) may have a maximum center and a minimum edge. The seventh gap (G7) between the seventh and eighth lenses (107, 108) may have a minimum center and a maximum edge.

[0203] FIG. 7 is a graph showing the aberration characteristics at the telescopic end of the optical system according to the present embodiment. The aberration graph in FIG. 7 shows the longitudinal spherical aberration, astigmatic field curves, and distortion measured from left to right. In FIG. 7, the X-axis may represent the focal length (mm) and distortion (%), and the Y-axis may represent the height of the image. Additionally, the graph for longitudinal spherical aberration is for light in the wavelength bands of approximately 435 nm, approximately 486 nm, approximately 546 nm, approximately 587 nm, and approximately 656 nm, and the graphs for astigmatic field curves and distortion are for light in the wavelength band of approximately 546 nm. In the aberration diagram of FIG. 7, it can be interpreted that the closer the curves at the telescopic end are to the Y-axis, the better the aberration correction function is. In the optical system (1000) according to the present embodiment, it can be seen that the measured values ​​are adjacent to the Y-axis in almost all areas. That is, the optical system (1000) according to the present embodiment has improved resolution and can have good optical performance not only in the center of the field of view (FOV) but also in the periphery.

[0205] The optical system (1000) according to the present embodiment disclosed above may satisfy at least one or two of the mathematical formulas described below. Accordingly, the optical system (1000) according to the present embodiment may have improved optical characteristics. For example, if the optical system (1000) satisfies at least one mathematical formula, the optical system (1000) can effectively control aberration characteristics such as chromatic aberration and distortion aberration, and may have good optical performance not only at the center of the field of view (FOV) but also at the periphery. In addition, the optical system (1000) may have improved resolution. Furthermore, regarding the meaning of the thickness of the lens at the optical axis (OA) and the spacing of adjacent lenses at the optical axis (OA) described in the mathematical formulas, one may refer to the present embodiment disclosed above.

[0207] [Mathematical Formula 1]

[0208] 2 < EFL_wide / L1R1 < 3

[0209] In Equation 1, EFL_wide is the total focal length of the optical system (1000) in the first mode, which is wide angle, and L1R1 represents the radius of curvature of the first surface (S1) of the first lens (101). When Equation 1 is satisfied, the radius of curvature of the first lens (101, 201), which has a significant influence on the optical system (1000), can be appropriately set to suppress the degradation of optical characteristics, and the optical system (1000) can control the incident light and set factors that affect aberrations. In this embodiment, Equation 1 can preferably satisfy 2 < EFL_wide / L1R1 < 2.5.

[0211] [Mathematical Formula 2]

[0212] 1 < L1R1 / EPD_wide < 2

[0213] In Equation 2, L1R1 represents the radius of curvature of the first surface (S1) of the first lens (101), and EPD_wide represents the diameter of the entrance pupil (effective aperture) in the first mode, the wide angle end (wide). If Equation 2 is satisfied, an image with brightness suitable for shooting can be provided, and a large amount of light can be received by the image sensor. In this embodiment, Equation 2 preferably satisfies 1 < L1R1 / EPD_wide < 1.5.

[0215] [Mathematical Formula 3]

[0216] 0.1 < Fno_wide / L1R1 < 1

[0217] In Equation 3, Fno_wide represents the F-number in the first mode, the wide angle section, and L1R1 represents the radius of curvature of the first surface (S1) of the first lens (101). If Equation 3 is satisfied, an image with brightness suitable for shooting can be provided, and a large amount of light can be received by the image sensor. In addition, the degradation of optical performance due to temperature changes can be improved. In this embodiment, Equation 3 preferably satisfies 0.1 < Fno_wide / L1R1 < 0.5.

[0219] [Mathematical Formula 4]

[0220] 3 < TTL / L1R1 < 5

[0221] In Equation 4, TTL (Total track length) refers to the distance (mm) along the optical axis (OA) from the vertex of the first surface (S1) of the first lens (101) to the top surface of the image sensor (300), and L1R1 refers to the radius of curvature of the first surface (S1) of the first lens (101). When Equation 4 is satisfied, the optical system (1000) can have an appropriate focal length within the set TTL range, and image formation can be achieved while maintaining an appropriate focal length for the mobile optical system. If it is below the lower limit of Equation 4, it is necessary to increase the refractive power of the lenses, making it difficult to correct spherical aberration or distortion aberration; if it exceeds the upper limit of Equation 4, the effective aperture or TTL of the lenses becomes longer, which may cause a problem where the imaging lens system becomes larger. In this embodiment, Equation 4 preferably satisfies 3.5 < TTL / L1R1 < 4.5.

[0223] [Mathematical Formula 5]

[0224] 3 < L1R2 / L1R1 < 5

[0225] In Equation 5, L1R1 represents the radius of curvature of the first surface (S1) of the first lens (101), and L1R2 represents the radius of curvature of the second surface (S2) of the first lens (101). When Equation 5 is satisfied, light incident on the optical system (1000) can be refracted to maintain an appropriate focal length and form an image. In this embodiment, Equation 5 can preferably satisfy 4 < L1R2 / L1R1 < 5.

[0227] [Mathematical Formula 6]

[0228] 0.5 < EFL_wide / f1 < 1.5

[0229] In Equation 6, EFL_wide is the total focal length of the optical system (1000) in the first mode, which is wide angle, and F1 is the focal length of the first lens (101). When Equation 6 is satisfied, the optical system (1000) can have a set angle of view and an appropriate focal length, and a mobile optical system can be provided. In addition, the angle of view can be set large within an appropriate TTL range through the first lens (101, 201) having a positive (+) refractive power. If it is below the lower limit of Equation 6, the effective aperture or TTL of the lenses becomes longer, and a problem may occur where the imaging lens system becomes large. If it exceeds the upper limit of Equation 6, the influence of the first lens (101) in the entire optical system decreases, and it is necessary to increase the refractive power of the lenses, which makes it difficult to correct spherical aberration or distortion aberration. In this embodiment, mathematical formula 6 can preferably satisfy 0.8 < EFL_wide / f1 < 1.2.

[0231] [Mathematical Formula 7]

[0232] L1R1 > 0, L1R2 > 0

[0233] In Equation 7, L1R1 represents the radius of curvature of the first surface (S1) of the first lens (101), and L1R2 represents the radius of curvature of the second surface (S2) of the first lens (101). When Equation 7 is satisfied, light incident on the optical system (1000) can be refracted to maintain an appropriate focal length and form an image.

[0235] [Mathematical Formula 8]

[0236] 20 < │f_LG1│ < 40

[0237] In Equation 8, LG1_F is the combined focal length of the first lens group (LG1). When Equation 8 is satisfied, the light path incident from the entire optical system is set, and the optical system can have good optical performance at the set angle of view and focal length. In this embodiment, Equation 8 can preferably satisfy 30 < │f_LG1│ < 35.

[0239] [Mathematical Formula 9]

[0240] 5 < │f_LG2│ < 10

[0241] In Equation 9, LG2_F is the combined focal length of the second lens group (LG2). When Equation 9 is satisfied, the light path incident from the entire optical system is set, and the optical system can have good optical performance at the set angle of view and focal length. In this embodiment, Equation 9 can preferably satisfy 7 < │f_LG2│ < 10.

[0243] [Mathematical Formula 10]

[0244] 10< │f_LG3│ < 30

[0245] In Equation 10, LG3_F is the combined focal length of the third lens group (LG3). When Equation 10 is satisfied, the light path incident from the entire optical system is set, and the optical system can have good optical performance at the set angle of view and focal length. In this embodiment, Equation 10 preferably satisfies 15 < │f_LG3│ < 20.

[0247] [Mathematical Formula 11]

[0248] 1.7 < n3 < 1.9

[0249] In Equation 11, n3 is the refractive index of the third lens (103). When Equation 11 is satisfied, the third lens (103) is the lens positioned closest to the sensor side in the first lens group (LG1), and chromatic aberration can be minimized by having a high refractive index. In this embodiment, Equation 11 can preferably satisfy 1.8 < n3 < 1.9.

[0251] [Mathematical Formula 12]

[0252] 30 < v3 < 55

[0253] In Equation 12, n3 is the Abbe number of the third lens (103). When Equation 12 is satisfied, the third lens (103) is the lens positioned closest to the sensor side in the first lens group (LG1), and chromatic aberration can be minimized by having a low Abbe number. In this embodiment, Equation 12 preferably satisfies 35 < v3 < 45.

[0255] [Mathematical Formula 13]

[0256] 20 < TTL < 36

[0257] In Equation 13, TTL (Total track length) refers to the distance (mm) along the optical axis (OA) from the center of the first surface (S1) of the first lens (101) to the top surface of the image sensor (300). If Equation 13 is satisfied, a suitable mobile optical system can be provided. In this embodiment, Equation 13 preferably satisfies 33 < TTL < 37.

[0259] [Mathematical Formula 14]

[0260] 5 < LG2 Stroke < 8

[0261] Equation 14 can set the range of the stroke length (LG2_stroke) of the second lens group (LG2). If the upper limit of Equation 14 is exceeded, the stroke length of the second lens group (LG2) increases during focusing, making it difficult to miniaturize the zoom lens. If the lower limit of Equation 14 is less than, the performance of the zoom optical system may be degraded. In this embodiment, Equation 14 can preferably satisfy 7 < LG2_stroke < 8.

[0263] [Mathematical Formula 15]

[0264] 7 < LG3 Stroke < 9

[0265] Equation 15 can set the range of the stroke length (LG3_stroke) of the third lens group (LG3). If the upper limit of Equation 15 is exceeded, the stroke length of the third lens group (LG3) increases during focusing, making it difficult to miniaturize the zoom lens. If the lower limit of Equation 15 is not met, the performance of the zoom optical system may be degraded. In this embodiment, Equation 15 can preferably satisfy 8 < LG3_stroke < 9.

[0267] [Mathematical Formula 16]

[0268] 3 < CA_max < 5

[0269] In Equation 16, CA_max represents the maximum effective aperture among the object sides and sensor sides of the lenses. If Equation 16 is satisfied, the optical system can maintain good optical performance and set a size for a slim and compact structure. In this embodiment, Equation 16 preferably satisfies 4 < CA_max < 5.

[0271] [Mathematical Formula 17]

[0272] 1.8 < nP1 < 1.9

[0273] In Equation 17, nP1 is the refractive index of the optical path control member (111). If Equation 17 is satisfied, the thickness in the direction perpendicular to the optical axis of the optical system (1000) can be reduced, and the degradation of the optical performance of the optical system (1000) can be minimized. In this embodiment, Equation 17 can preferably satisfy 1.83 < nP1 < 1.86.

[0275] [Mathematical Formula 18]

[0276] 0.1 < TD_LG2 / TD_LG3 < 1

[0277] Equation 18 can establish a relationship between the length (TD_LG2) of the second lens group (LG2) in the optical axis direction and the length (TD_LG3) of the third lens group (LG3) in the optical axis direction. Equation 18 is a condition for reducing aberrations and improving optical performance. The second lens group (LG2) and the third lens group (LG3) satisfying Equation 18 can appropriately correct astigmatism and coma aberrations. In addition, the overall length of the zoom optical system having an appropriate zoom magnification can be reduced. In this embodiment, Equation 18 can preferably satisfy 0.5 < TD_LG2 / TD_LG3 < 1.

[0279] [Mathematical Formula 19]

[0280] 1.5 < f_tele / f_wide < 2.5

[0281] Equation 19 can establish the relationship between the total focal length (f_tele) of the optical system (1000) in the third mode (tele) and the total focal length (f_wide) of the optical system (1000) in the first mode (wide). f_tele / f_wide may be referred to as the magnification ratio or zoom magnification of the zoom lens optical system. Equation 19 is a condition for limiting zoom optical performance.

[0282] If the upper limit of Equation 19 is exceeded, it is difficult to secure optical performance due to chromatic aberration in the telephoto end (tele), and the amount of movement of each lens group increases significantly during zooming, making mechanical miniaturization difficult. If it is below the lower limit of Equation 19, it is difficult to secure performance as a zoom optical system. A zoom optical system satisfying Equation 19 can secure substantially useful optical performance. In this embodiment, Equation 19 can preferably satisfy 1.5 < f_tele / f_wide < 2.

[0284] [Mathematical Formula 20]

[0285] 3 < TTL / CA_max < 5

[0286] In Equation 20, CA_max represents the largest effective diameter (mm) among the object side and sensor side of the plurality of lenses, and TTL (Total track length) represents the distance (mm) along the optical axis (OA) from the vertex of the first surface (S1) of the first lens (101) to the top surface of the image sensor (300). Equation 20 establishes the relationship between the total optical axis length of the optical system and the maximum effective diameter, thereby providing an improved mobile optical system. In this embodiment, Equation 20 preferably satisfies 4 < TTL / CA_max < 5.

[0288] [Mathematical Formula 21]

[0289] 4 < TTL / ImgH < 6

[0290] In Equation 21, TTL (Total track length) refers to the distance (mm) along the optical axis (OA) from the vertex of the first surface (S1) of the first lens to the top surface of the image sensor (300), and ImgH refers to the maximum diagonal length of the image sensor (300). When Equation 21 is satisfied, the optical system (1000) can have a TTL for application to the mobile image sensor (300), thereby providing improved image quality. If it is below the lower limit of Equation 2, it is necessary to increase the refractive power of the lenses, making it difficult to correct spherical aberration or distortion aberration; if it exceeds the upper limit of Equation 2, the effective aperture or TTL of the lenses becomes longer, which may cause a problem where the imaging lens system becomes larger. In the embodiment, Equation 21 preferably satisfies 4 < TTL / ImgH < 5.

[0292] [Mathematical Formula 22]

[0293] 2 < f_wide / ImgH < 3

[0294] In Equation 22, f_wide is the total effective focal length of the optical system (1000) in the first mode, which is wide, and ImgH represents the maximum diagonal length of the image sensor (300). If Equation 22 is satisfied, the mobile image sensor (300) can have improved aberration characteristics in terms of size. In this embodiment, Equation 22 preferably satisfies 2.5 < F_wide / ImgH < 3.

[0296] [Mathematical Formula 23]

[0297] 3 < f_tele / ImgH < 5

[0298] In Equation 23, f_tele is the total effective focal length of the optical system (1000) in the telescopic end (tele), which is the third mode, and ImgH represents the maximum diagonal length of the image sensor (300). If Equation 23 is satisfied, the mobile image sensor (300) may have improved aberration characteristics in terms of size. In this embodiment, Equation 23 preferably satisfies 4 < f_tele / ImgH < 5.

[0300] [Mathematical Formula 24]

[0301] 1 < CA_max / CA_min < 2

[0302] In Equation 24, CA_max represents the maximum effective diameter among the object sides and sensor sides of the lenses, and CA_min represents the minimum effective diameter among the object sides and sensor sides of the lenses. When Equation 24 is satisfied, the optical system can set a size for a slim and compact structure while maintaining optical performance. In this embodiment, Equation 24 preferably satisfies 1 < CA_max / CA_min < 1.5.

[0304] [Mathematical Formula 25]

[0305] 1 < CA_max / ImgH < 2

[0306] In Equation 25, CA_max represents the maximum effective diameter among the object sides and sensor sides of the lenses, and ImgH represents the maximum diagonal length of the image sensor (300). When Equation 25 is satisfied, the optical system can maintain good optical performance and set a size for a slim and compact structure. In this embodiment, Equation 25 can preferably satisfy 1 < CA_max / ImgH < 1.5.

[0308] [Mathematical Formula 26]

[0309]

[0310] In Equation 26, Z represents Sag, which can mean the distance in the direction of the optical axis from any position on the aspherical surface to the vertex of the aspherical surface. Y represents the distance in the direction perpendicular to the optical axis from any position on the aspherical surface to the optical axis. c can represent the curvature of the lens, and K can represent the conic constant. Additionally, A, B, C, D, E, and F can represent the aspheric constants.

[0312] The optical system (1000) according to the present embodiment may satisfy at least one or two of the mathematical formulas 1 to 26. In this case, the optical system (1000) may have improved optical characteristics. Specifically, when the optical system (1000) satisfies at least one or two of the mathematical formulas 1 to 26, the optical system (1000) may have improved resolution and may improve aberration and distortion characteristics. In addition, the optical system (1000) may secure a Back Focal Length (BFL) for applying a mobile image sensor (300), compensate for the degradation of optical characteristics due to temperature changes, and minimize the gap between the last lens and the image sensor (300), thereby having good optical performance in the center and periphery of the field of view (FOV).

[0314] Table 4 shows the result values ​​for the above-described mathematical formulas 1 to 25 in the optical system (1000) of the embodiment. Referring to Table 6, it can be seen that the optical system (1000) satisfies at least one, two or more, or three or more of mathematical formulas 1 to 25. Specifically, it can be seen that the optical system (1000) according to the embodiment satisfies all of mathematical formulas 1 to 25. Accordingly, the optical system (1000) can have good optical performance and excellent optical characteristics at the center and periphery of the field of view (FOV).

[0316] 수학식 본 실시예 1 2 < EFL_wide / L1R1 < 3 2.246 2 1 < L1R1 / EPD_wide < 2 1.256 3 0.1 < Fno_wide / L1R1 < 1 0.323 4 3 < TTL / L1R1 < 5 4.003 5 3 < L1R2 / L1R1 < 5 4.893 6 0.5 < EFL_wide / f1 < 1.5 1.005 7 L1R1 > 0, L1R2 > 0 만족 8 20 < │f_LG1│ < 40 32.596 9 5 < │f_LG2│ < 10 9.333 10 10< │f_LG3│ < 30 19.493 11 1.7 < n3 < 1.9 1.811 12 30 < v3< 55 40.730 13 20 < TTL < 36 35.000 14 5 < LG2 Stroke < 8 7.287 15 7 < LG3 Stroke < 9 8.600 16 3 < CA_max < 5 4.100 17 1.8 < nP1 < 1.9 1.855 18 0.1 < TD_LG2 / TD_LG3 < 1 0.739 19 1.5 < f_tele / f_wide < 2.5 1.999 20 3 < TTL / CA_max < 5 4.424 21 4 < TTL / ImgH < 6 4.960 22 2 < f_wide / ImgH < 3 2.783 23 5 < f_tele / ImgH < 6 5.564 24 1 < CA_max / CA_min < 2 1.433 25 1 < CA_max / ImgH < 2 1.121

[0318] FIG. 9 is an example of a portable terminal having an optical system according to the present embodiment. As illustrated in FIG. 9, the portable terminal (1500) may include a camera module (1520), a flash module (1530), and an autofocus device (1510) provided on one side or the rear side. Here, the autofocus device (1510) may include a surface-emitting laser element and a light receiver disclosed above as a light-emitting layer.

[0319] The flash module (1530) may include an emitter that emits light inside it. The flash module (1530) may be operated by the camera operation of the mobile terminal or by the control of the user. The camera module (1520) may include an image capturing function and an autofocus function. For example, the camera module (1520) may include an autofocus function using an image.

[0320] The autofocus device (1510) may include an autofocus function using a laser. The autofocus device (1510) may be primarily used under conditions where the autofocus function using the image of the camera module (1520) is degraded. Additionally, although not shown in the drawing, at least one additional camera module may be disposed on the front of the mobile terminal (1500). At least one of the camera modules within the mobile terminal may have the tele-type folded optical system disclosed above.

[0321] An optical system or camera module according to an embodiment of the invention, and a lens assembly according to various embodiments, may be applied to an electronic device employing an image sensor, for example. A lens assembly according to an exemplary embodiment may be applied to various electronic devices such as digital cameras, interchangeable lens cameras, video cameras, mobile phone cameras, cameras for small mobile devices, VR, AR, drones, or manned / unmanned aircraft.

[0322] The features, structures, effects, etc. described in the embodiments above are included in at least one embodiment of the present invention and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment may be combined or modified and implemented in other embodiments by a person skilled in the art to which the embodiments belong. Therefore, details regarding such combinations and modifications should be interpreted as being included within the scope of the present invention.

[0323] Furthermore, although the invention has been described above with reference to embodiments, this is merely illustrative and does not limit the invention. Those skilled in the art will understand that various modifications and applications not exemplified above are possible within the scope of the essential characteristics of the embodiments. For example, each component specifically shown in the embodiments may be modified and implemented. Differences related to such modifications and applications should be interpreted as being included within the scope of the invention as defined in the appended claims.

Claims

Claim 1 An optical system comprising first to third lens groups arranged along an optical axis, wherein the first lens group has a negative (-) refractive power, the second lens group has a positive (+) refractive power, and the third lens group has a negative (-) refractive power, wherein the first lens group is a fixed group, and the second lens group and the third lens group are moving groups, and the stroke length of the second lens group is smaller than the stroke length of the third lens group. Claim 2 In claim 1, the lens positioned closest to the object side in the second lens group is an optical system having a shape that is convex on both sides at the optical axis. Claim 3 In claim 1, the lens positioned closest to the sensor side in the first lens group is an optical system having a shape in which both sides are concave at the optical axis. Claim 4 An optical system according to claim 1, wherein the first lens group comprises a first lens having a positive (+) refractive power, a second lens having a positive (+) refractive power, and a fourth lens having a negative (-) refractive power, and the second lens group comprises a fifth lens having a positive (+) refractive power and a sixth lens having a negative (-) refractive power. Claim 5 In claim 1, the third lens group comprises a sixth lens having negative (-) refractive power, a seventh lens having positive (+) refractive power, and an eighth lens having negative (-) refractive power, forming an optical system. Claim 6 An optical system according to claim 1, wherein an optical path control member is disposed on the object side of the first lens group, and an aperture is disposed between the first lens group and the second lens group. Claim 7 In claim 1, the first to third lens groups comprise two or more lenses having different refractive powers. Claim 8 In claim 1, the lens positioned closest to the object side in the first lens group is an optical system having a meniscus shape that is convex toward the object side from the optical axis. Claim 9 An optical system satisfying the following conditional equation in claim 1: <Conditional Equation> 0.1 < TD_LG2 / TD_LG3 < 1 (wherein TD_LG2 is the length of the second lens group in the direction of the optical axis, and TD_LG3 is the length of the third lens group in the direction of the optical axis.) Claim 10 An optical system according to claim 1 that satisfies the following conditional equation: <Conditional Equation> 1.7 < n3 < 1.9 (wherein n3 is the refractive index of the third lens.) Claim 11 An optical system comprising first to eight lenses arranged along an optical axis, wherein the first lens has a positive (+) refractive power, the second lens has a positive (+) refractive power, the third lens has a negative (-) refractive power, the fourth lens has a positive (+) refractive power, the fifth lens has a negative (-) refractive power, the sixth lens has a negative (-) refractive power, the seventh lens has a positive (+) refractive power, and the eighth lens has a negative (-) refractive power, wherein the third lens has a concave shape on both sides along the optical axis, and the fourth lens has a convex shape on both sides along the optical axis. Claim 12 In claim 11, the optical system in which the first lens among the first to eight lenses has the largest effective diameter. Claim 13 In claim 11, the optical system in which the first lens at the optical axis has a meniscus shape that is convex toward the object. Claim 14 An optical system according to claim 11, wherein an optical path control member is disposed on the object side of the first lens, and an aperture is disposed between the third lens and the fourth lens. Claim 15 In Clause 11, an optical system satisfying the following conditional equation: <Conditional Equation> 4 < TTL / ImgH < 6 (wherein TTL is the optical axis distance from the vertex of the object side of the first lens to the top plane of the image sensor, and ImgH is the maximum diagonal length of the image sensor.)

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