Zoom lens

Abstract

The present invention relates to a zoom lens, which comprises, in order from the object side to the image side along the optical axis: a first fixed lens group (G1) with positive focal power, a first zoom lens group (G2) with negative focal power, an aperture stop (STO), a second fixed lens group (G3) with positive focal power, a second zoom lens group (G4) with positive focal power, and a focus lens group (G5) with positive focal power. The first zoom lens group (G2), the second zoom lens group (G4) and the focus lens group (G5) can all move along the optical axis, and a focal length (FG5) of the focus lens group (G5) and a focal length (FW) of the zoom lens at a wide angle end satisfy a relationship of 4.0≤FG5 / FW≤5.0. The zoom lens of the present invention has a zoom ratio of more than 25 times and a maximum aperture of F1.6, taking into account a large zoom ratio, a wide angle, low distortion and a smaller size, and effectively corrects chromatic aberration, making the purple fringing of the full focal length less than 4 pixels, and ensuring that the resolution of the full focal length meets 4K imaging.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a zoom lens. Background Art

[0002] With the development of the internet and the increasing demand for video conferencing, and the advent of the 5G era, the high-end market is demanding ever-higher image clarity, with 4K resolution becoming mainstream. Existing high-magnification zoom lenses, most of which have a resolution of around 2M, no longer meet current user needs. Furthermore, optical system miniaturization is generally difficult due to the limitations of high magnification, wide angle, and low distortion. Furthermore, existing high-magnification zoom lenses on the market often suffer from severe purple fringing, which severely impacts the overall image quality. Summary of the Invention

[0003] To overcome the defects in the above-mentioned prior art, the present invention provides a zoom lens with a zoom ratio of more than 25 times and a maximum aperture of F1.6. It takes into account a large zoom ratio, wide angle, low distortion and smaller size, effectively corrects chromatic aberration, makes the purple fringing of the entire focal length less than 4 pixels, has a good purple fringing effect, and ensures that the resolution of the entire focal length meets 4K imaging.

[0004] To achieve the above-mentioned objectives, the present invention provides a zoom lens comprising, in order from the object side to the image side along the optical axis, a first fixed lens group with positive optical power, a first zoom lens group with negative optical power, an aperture stop, a second fixed lens group with positive optical power, a second zoom lens group with positive optical power, and a focus lens group with positive optical power. The first zoom lens group, the second zoom lens group, and the focus lens group are all movable along the optical axis. The focal length FG5 of the focus lens group and the focal length FW of the zoom lens at the wide-angle end satisfy the relationship: 4.0≤FG5 / FW≤5.0.

[0005] According to one aspect of the present invention, the focal length FG1 of the first fixed lens group satisfies the relationship: 8.5≤FG1 / FW≤10.5;

[0006] The focal length FG2 of the first zoom lens group satisfies the relationship: -2.5≤FG2 / FW≤-1.5;

[0007] The focal length FG4 of the second zoom lens group satisfies the relationship: 4.2≤FG4 / FW≤5.0;

[0008] Wherein, FW is the focal length of the zoom lens at the wide-angle end.

[0009] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0010] The first fixed lens group includes, in sequence, a first lens with negative optical power, a second lens with positive optical power, a third lens with positive optical power, and a fourth lens with positive optical power;

[0011] The first lens and the second lens are cemented together to form a cemented lens.

[0012] According to one aspect of the present invention, the object-side surface of the first lens is convex and the image-side surface is concave;

[0013] The object-side surfaces of the second lens, the third lens, and the fourth lens are all convex.

[0014] According to one aspect of the present invention, the Abbe number Ab2 of the material of the second lens, the Abbe number Ab3 of the material of the third lens, and the Abbe number Ab4 of the material of the fourth lens respectively satisfy the following relationships: Ab2≥70; Ab3≥70; Ab4≥65.

[0015] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0016] The first zoom lens group includes, in sequence, a fifth lens with negative optical power, a sixth lens with negative optical power, a seventh lens with negative optical power, and an eighth lens with positive optical power.

[0017] According to one aspect of the present invention, the image-side surfaces of the fifth lens and the sixth lens are both concave;

[0018] The object-side surface and the image-side surface of the seventh lens are both concave;

[0019] The object-side surface and the image-side surface of the eighth lens are both convex.

[0020] According to one aspect of the present invention, the seventh lens and the eighth lens are cemented together to form a doublet lens.

[0021] According to one aspect of the present invention, the Abbe number Ab7 of the material of the seventh lens satisfies the relationship: Ab7≥70.

[0022] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0023] The second fixed lens group includes, in sequence, a ninth lens having positive optical power and a tenth lens having negative optical power.

[0024] According to one aspect of the present invention, both the object-side surface and the image-side surface of the ninth lens are convex.

[0025] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0026] The second zoom lens group includes, in sequence, an eleventh lens having positive optical power, a twelfth lens having negative optical power, a thirteenth lens having positive optical power, a fourteenth lens having positive optical power, and a fifteenth lens having negative optical power.

[0027] According to one aspect of the present invention, the object-side surface and the image-side surface of the eleventh lens are both convex;

[0028] The object side surfaces of the thirteenth lens and the fourteenth lens are both convex;

[0029] The image-side surface of the fifteenth lens is concave.

[0030] According to one aspect of the present invention, the material Abbe number Ab of the thirteenth lens 13 Satisfy the relationship: Ab 13 ≥70.

[0031] According to one aspect of the present invention, the material Abbe number Ab of the fourteenth lens 14 Satisfy the relationship: Ab 14 ≤25.

[0032] According to one aspect of the present invention, along the direction from the object side to the image side of the optical axis,

[0033] The focusing lens group sequentially includes a sixteenth lens with positive or negative optical power, a seventeenth lens with positive or negative optical power, and an eighteenth lens with positive or negative optical power.

[0034] According to one aspect of the present invention, the zoom lens includes at least one glass aspherical lens.

[0035] According to one aspect of the present invention, the stroke D2 of the first zoom lens group and the stroke D4 of the second zoom lens group satisfy the relationship: 1.5≤|D2 / D4|≤2.0.

[0036] According to one aspect of the present invention, the focal length FG2 of the first zoom lens group and the focal length FG4 of the second zoom lens group satisfy the relationship: -0.46≤FG2 / FG4≤-0.30.

[0037] According to one aspect of the present invention, the maximum lens diameter ΦG1 of the first fixed lens group and the total length TTL of the zoom lens satisfy the relationship: ΦG1 / TTL≤0.4.

[0038] According to the solution of the present invention, by adopting a five-group architecture of "positive-negative-positive-positive-positive" and a three-group linkage method of "two zooms, one focus", the zoom lens can achieve a zoom ratio of more than 25 times and a maximum aperture of F1.6. The rational design of the above-mentioned architecture effectively corrects large-angle distortion, and the maximum optical distortion of the entire focal length is less than 5%, making the imaging picture uniform and undistorted. In addition, by specifically combining the focal length of the five groups, the shape of the object side and image side of each lens in the five groups, and the rational combination of lens surface shapes, while achieving a large zoom ratio and wide-angle low distortion, it also takes into account the smaller size and miniaturization of the optical system, while ensuring that the resolution of the entire focal length meets 4K imaging.

[0039] By carefully selecting specific glass materials for the 18 lenses, optimally combining cemented lenses, and distributing focal lengths, chromatic aberration is effectively corrected, minimizing purple fringing to less than four pixels across the entire focal range. This results in excellent imaging, enhanced purple fringing, and improved chromatic aberration. Furthermore, effective correction of lens component tolerances ensures excellent assembly and processability, improving the resolution of the zoom lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram schematically illustrates the structure of a zoom lens according to Embodiment 1 of the present invention;

[0041] Figure 2 Schematically showing a defocus curve of the zoom lens at the wide-angle end according to Example 1 of the present invention;

[0042] Figure 3 Schematically showing a defocus curve of the zoom lens at the telephoto end according to Example 1 of the present invention;

[0043] Figure 4 A schematic diagram schematically illustrates the structure of a zoom lens according to Embodiment 2 of the present invention;

[0044] Figure 5 Schematically showing a defocus curve of the zoom lens at the wide-angle end according to Example 2 of the present invention;

[0045] Figure 6 Schematically showing a defocus curve of the zoom lens at the telephoto end according to Example 2 of the present invention;

[0046] Figure 7 A schematic diagram schematically illustrates the structure of a zoom lens according to Embodiment 3 of the present invention;

[0047] Figure 8 Schematically showing a defocus curve of the zoom lens at the wide-angle end according to Example 3 of the present invention;

[0048] Figure 9 The figure schematically shows the defocus curve of the zoom lens at the telephoto end according to Example 3 of the present invention. DETAILED DESCRIPTION

[0049] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0050] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0051] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0052] like Figure 1 As shown, the zoom lens of the present invention comprises, in order from the object side to the image side along the optical axis: a first fixed lens group G1 with positive optical power, a first zoom lens group G2 with negative optical power, an aperture stop STO, a second fixed lens group G3 with positive optical power, a second zoom lens group G4 with positive optical power, and a focus lens group G5 with positive optical power. The first and second zoom lens groups G2 and G4 are movable along the optical axis for optical zooming between the wide-angle and telephoto ends of the zoom lens. The focus lens group G5 is also movable along the optical axis to compensate for changes in the image plane position during optical zooming. Furthermore, the focal length FG5 of the focus lens group G5 and the focal length FW of the zoom lens at the wide-angle end satisfy the relationship: 4.0 ≤ FG5 / FW ≤ 5.0. This achieves compatibility between high magnification and compact size, ensuring 4K resolution across the entire focal range of the lens.

[0053] By employing a five-group "positive-negative-positive-positive-positive" architecture and a three-group linkage approach (two zooms, one focus), the zoom lens of this invention rationally allocates the optical power, focal length, and object and image-side shapes of each lens within the five groups, resulting in a zoom ratio exceeding 25x and a maximum aperture of F1.6. This rational design effectively corrects wide-angle distortion, with maximum optical distortion of less than 5% across the entire focal range, ensuring uniform, undistorted imaging. While achieving a large zoom ratio, wide angle, and low distortion, it also ensures 4K resolution across the entire focal range.

[0054] In the present invention, the focal length FG1 of the first fixed lens group G1, the focal length FG2 of the first zoom lens group G2, and the focal length FG4 of the second zoom lens group G4 respectively satisfy the following relationships:

[0055] 8.5≤FG1 / FW≤10.5;

[0056] -2.5≤FG2 / FW≤-1.5;

[0057] 4.2≤FG4 / FW≤5.0;

[0058] Here, FW is the focal length of the zoom lens at the wide-angle end.

[0059] In this invention, along the optical axis from the object side to the image side, the first fixed lens group G1 comprises, in order: a first lens L1 having negative refractive power, a second lens L2 having positive refractive power, a third lens L3 having positive refractive power, and a fourth lens L4 having positive refractive power. The object-side surface of the first lens L1 is convex and its image-side surface is concave. The object-side surfaces of the second lens L2, the third lens L3, and the fourth lens L4 are all convex.

[0060] In this invention, along the optical axis from the object side to the image side, the first zoom lens group G2 comprises, in order: a fifth lens element L5 having negative refractive power, a sixth lens element L6 having negative refractive power, a seventh lens element L7 having negative refractive power, and an eighth lens element L8 having positive refractive power. The image-side surfaces of the fifth lens element L5 and the sixth lens element L6 are both concave, the object-side and image-side surfaces of the seventh lens element L7 are both concave, and the object-side and image-side surfaces of the eighth lens element L8 are both convex.

[0061] In the present invention, along the optical axis from the object side to the image side, the second fixed lens group G3 includes: a ninth lens L9 with positive optical power and a tenth lens L10 with negative optical power. Both the object-side and image-side surfaces of the ninth lens L9 are convex.

[0062] In the present invention, the second zoom lens group G4 comprises, along the optical axis from the object side to the image side, an eleventh lens group L11 having positive refractive power, a twelfth lens group L12 having negative refractive power, a thirteenth lens group L13 having positive refractive power, a fourteenth lens group L14 having positive refractive power, and a fifteenth lens group L15 having negative refractive power. The object-side and image-side surfaces of the eleventh lens group L11 are both convex, the object-side surfaces of the thirteenth lens group L13 and the fourteenth lens group L14 are both convex, and the image-side surface of the fifteenth lens group L15 is concave.

[0063] In the present invention, along the direction from the object side to the image side of the optical axis, the focusing lens group G5 includes: a sixteenth lens L16 with positive or negative optical power, a seventeenth lens L17 with positive or negative optical power, and an eighteenth lens L18 with positive or negative optical power.

[0064] In this invention, the zoom lens includes at least one glass aspherical lens. This combination of spherical and aspherical lenses effectively corrects various aberrations within the zoom lens, improving resolution. By rationally distributing the focal powers of the 18 lenses and selecting specific glass materials, chromatic aberration is corrected, reducing purple fringing to less than four pixels across the entire focal range, resulting in excellent imaging quality. Furthermore, the five specific focal powers, determined by the focal powers of each lens in the five lens groups, effectively correct for lens component tolerances and ensure excellent assembly and processability.

[0065] In the present invention, first lens L1 and second lens L2 are cemented together to form a doublet. Seventh lens L7 and eighth lens L8 are cemented together to form a doublet. This doublet effectively corrects chromatic aberration, improves the resolution of the zoom lens, and enhances its ease of assembly.

[0066] In this invention, the Abbe number Ab2 of the material of second lens L2, the Abbe number Ab3 of the material of third lens L3, and the Abbe number Ab4 of the material of fourth lens L4 respectively satisfy the following relationships: Ab2 ≥ 70; Ab3 ≥ 70; and Ab4 ≥ 65. By designing and combining different Abbe coefficients for second through fourth lenses L2 through L4, chromatic aberration at the telephoto end of the zoom lens can be effectively corrected, further improving resolution.

[0067] The Abbe number Ab7 of the material of seventh lens element L7 satisfies the relationship: Ab7 ≥ 70, and the Abbe number Ab13 of the material of thirteenth lens element L13 satisfies the relationship: Ab13 ≥ 70. The Abbe coefficients of seventh and thirteenth lens elements L7 and L13 have been designed to effectively correct chromatic aberration of the zoom lens and improve imaging resolution. The Abbe number Ab14 of the material of fourteenth lens element L14 satisfies the relationship: Ab14 ≤ 25, effectively correcting chromatic aberration and reducing purple fringing.

[0068] In the present invention, the stroke D2 of the first zoom lens group G2 and the stroke D4 of the second zoom lens group G4 satisfy the relationship: 1.5 ≤ |D2 / D4| ≤ 2.0. The focal length FG2 of the first zoom lens group G2 and the focal length FG4 of the second zoom lens group G4 satisfy the relationship: -0.46 ≤ FG2 / FG4 ≤ -0.30. By designing and combining the stroke ratio and focal length ratio of the first zoom lens group G2 and the second zoom lens group G4, a zoom lens can achieve both high magnification and compact size.

[0069] In the present invention, the maximum lens diameter ΦG1 of the first fixed lens group G1 and the total optical length TTL of the zoom lens satisfy the relationship: ΦG1 / TTL ≤ 0.4. By limiting the ratio and range of the maximum lens diameter ΦG1 of the first fixed lens group G1 to the total optical length TTL of the lens, the zoom lens can be further miniaturized.

[0070] The zoom lens is described below using three specific embodiments. In each of the following embodiments, the object side is denoted as OBJ, the image side is denoted as IMA, the aperture stop STO is denoted as one surface, and the cemented surface of the cemented lens assembly is denoted as one surface. For example, a doublet lens composed of two cemented lenses has three surfaces.

[0071] Parameters of various embodiments that specifically meet the above conditional formula are shown in Table 1 below:

[0072] Relational Example 1 Example 2 Example 3 8.5≤FG1 / FW≤10.5 9.85 8.8 10.32 -2.5≤FG2 / FW≤-1.5 -2.37 -1.86 -1.66 4.2≤FG4 / FW≤5.0 4.43 4.97 4.76 4.0≤FG5 / FW≤5.0 4.82 4.14 4.6 Ab2≥70 81.6 81.6 71.5 Ab3≥70 81.6 81.6 81.6 Ab4≥65 81.6 68.6 81.6 Ab7≥70 71.5 81.6 81.6 Ab13≥70 90.2 81.6 95.1 Ab14≤25 17.9 17.9 16.5 1.5≤|D2 / D4|≤2.0 1.84 1.77 1.51 -0.46≤FG2 / FG4≤-0.30 -0.37 -0.33 -0.44 ΦG1 / TTL≤0.4 0.38 0.37 0.35

[0073] Table 1

[0074] In the present invention, the aspherical lens of the zoom lens satisfies the following formula:

[0075]

[0076] In the above formula, z is the axial distance from the surface to the vertex at a height h perpendicular to the optical axis along the optical axis; c represents the curvature at the vertex of the aspheric surface; k is the quadratic constant of the surface; A4, A6, A8, A 10 、A 12 、A 14 、A 16 ···represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order···aspheric coefficients respectively.

[0077] Example 1

[0078] The parameters of each lens of the zoom lens of this embodiment include: surface type, curvature radius (R value), thickness, refractive index of the material, and Abbe number, as shown in Table 2 below:

[0079]

[0080]

[0081] Table 2

[0082] The aspheric coefficients of the aspheric lenses of the zoom lens of this embodiment include: the quadratic surface constant K, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , as shown in Table 3 below.

[0083]

[0084]

[0085] Table 3

[0086] The zoom data at the wide-angle end and the telephoto end of the zoom lens of this embodiment are shown in Table 4 below.

[0087] Wide-angle end Telephoto end T1 0.8 40.8 T2 40.5 0.5 T3 23.2 1.5 T4 2.8 11.8 T5 2.9 15.6

[0088] Table 4

[0089] See also Figures 1 to 3 , combined with Table 1 to Table 4, in this embodiment, the zoom lens uses a total of 18 lenses. One of the lenses is a glass aspheric lens, and one lens is a plastic aspheric lens. The wide-angle end aperture of this lens can reach 1.6, the magnification ratio exceeds 25 times, it can effectively correct position chromatic aberration and magnification chromatic aberration, has a good purple fringing effect, a maximum distortion of less than 5%, no defocus in the temperature range of -30℃ to +70℃, and a full focal length 4K resolution. The zoom lens achieves wide angle, low distortion, small size, large aperture, small temperature drift, and is suitable for a variety of scenarios. While maintaining good optical performance, the zoom lens has good assembly tolerance, is conducive to production assembly, and has a high production yield. Figures 2 to 3 This reflects the above performance of the zoom lens of this embodiment.

[0090] Example 2

[0091] The parameters of each lens of the zoom lens of this embodiment include: surface type, curvature radius (R value), thickness, refractive index of the material, and Abbe number, as shown in Table 5 below:

[0092]

[0093]

[0094] Table 5

[0095] The aspheric coefficients of the aspheric lenses of the zoom lens of this embodiment include: the quadratic surface constant K, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , as shown in Table 6 below.

[0096] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S20 0.3843 -2.8584E-05 6.7744E-08 3.7630E-10 2.4369E-12 S21 0.0000 1.8646E-05 -7.5123E-08 9.1830E-10 0.0000E+00 S34 0.0000 -5.2341E-06 -2.8625E-07 0.0000E+00 0.0000E+00 S35 0.0000 5.8761E-05 3.3359E-08 0.0000E+00 0.0000E+00

[0097] Table 6

[0098] The zoom data at the wide-angle end and the telephoto end of the zoom lens of this embodiment are shown in Table 7 below.

[0099]

[0100]

[0101] Table 7

[0102] See also Figures 4 to 6 Combining Tables 1, 5, and 7, in this embodiment, the zoom lens utilizes a total of 18 lenses. Two of these lenses are glass aspherical lenses. This zoom lens boasts an aperture of up to 1.6 at the wide-angle end, a zoom ratio exceeding 25x, corrects positional and magnification chromatic aberrations, achieves excellent purple fringing, maintains focus within a temperature range of -30°C to +70°C, exhibits maximum distortion of less than 5%, and achieves 4K resolution at all focal lengths. This lens combines a small size, a large aperture, and minimal temperature drift, making it suitable for a variety of scenarios. Figures 5 and 6 This reflects the above performance of the zoom lens of this embodiment.

[0103] Example 3

[0104] The parameters of each lens of the zoom lens of this embodiment include: surface type, curvature radius (R value), thickness, refractive index of the material, and Abbe number, as shown in Table 8 below:

[0105]

[0106]

[0107] Table 8

[0108] The aspheric coefficients of the aspheric lenses of the zoom lens of this embodiment include: the quadratic surface constant K, the fourth-order aspheric coefficient A4, the sixth-order aspheric coefficient A6, the eighth-order aspheric coefficient A8, the tenth-order aspheric coefficient A 10 , as shown in Table 9 below.

[0109] Surface number K <![CDATA[A4]]> <![CDATA[A6]]> <![CDATA[A8]]> <![CDATA[A 10 ]]> S20 0.2691 -2.2796E-05 -1.0064E-07 6.3012E-10 -1.8090E-12 S21 -0.6044 1.4078E-05 -1.2716E-07 1.4510E-09 -5.1881E-12 S34 4.8248 -1.6030E-05 -1.2930E-06 3.1875E-08 -6.8574E-10 S35 1.3958 1.1694E-04 -2.3764E-07 2.5964E-08 -5.0508E-10

[0110] Table 9

[0111] The zoom data at the wide-angle and telephoto ends of the zoom lens of this embodiment are shown in Table 10 below.

[0112] Wide-angle end Telephoto end T1 0.8 40.5 T2 40.8 1.1 T3 27.8 1.5 T4 2.8 12.3 T5 2.9 19.7

[0113] Table 10

[0114] See also Figures 7 to 9, combined with Table 1, Table 8 to Table 10, in this embodiment, the zoom lens uses a total of 18 lenses. One of the lenses is a glass aspheric lens, and one lens is a plastic aspheric lens. The zoom lens has an aperture of up to 1.6 at the wide-angle end, a zoom ratio of more than 25 times, a maximum distortion of less than 4%, corrects positional chromatic aberration and magnification chromatic aberration, has a good purple fringing effect, does not lose focus in the temperature range of -30℃ to +70℃, and has a full focal length 4K resolution. This lens combines small size, wide angle, low distortion, large aperture and small temperature drift, making it suitable for a variety of scenarios. Figures 8 and 9 This reflects the above performance of the zoom lens of this embodiment.

[0115] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A zoom lens, comprising, in order from the object side to the image side along the optical axis: A first fixed lens group (G1) with positive optical power, a first zoom lens group (G2) with negative optical power, an aperture stop (STO), a second fixed lens group (G3) with positive optical power, a second zoom lens group (G4) with positive optical power, and a focus lens group (G5) with positive optical power, a total of five lens groups, the first zoom lens group (G2), the second zoom lens group (G4) and the focus lens group (G5) can all move along the optical axis, characterized in that, The first zoom lens group (G2) comprises, in sequence, a fifth lens (L5) with negative optical power, a sixth lens (L6) with negative optical power, a seventh lens (L7) with negative optical power, and an eighth lens (L8) with positive optical power, a total of four lenses; The second zoom lens group (G4) includes, in sequence, an eleventh lens (L11) with positive optical power, a twelfth lens (L12) with negative optical power, a thirteenth lens (L13) with positive optical power, a fourteenth lens (L14) with positive optical power, and a fifteenth lens (L15) with negative optical power, a total of five lenses; The focal length FG5 of the focus lens group (G5) and the focal length FW of the zoom lens at the wide angle end satisfy the relationship: 4.0≤FG5 / FW≤5.

0.

2. The zoom lens according to claim 1, wherein: Along the direction from the object side to the image side of the optical axis, The first fixed lens group (G1) comprises, in sequence, a first lens (L1) with negative optical power, a second lens (L2) with positive optical power, a third lens (L3) with positive optical power, and a fourth lens (L4) with positive optical power, a total of four lenses; The first lens (L1) and the second lens (L2) are cemented together to form a cemented lens.

3. The zoom lens according to claim 2, wherein: The object side surface of the first lens (L1) is convex and the image side surface is concave; The object-side surfaces of the second lens (L2), the third lens (L3) and the fourth lens (L4) are all convex.

4. The zoom lens according to claim 2, wherein: The Abbe number Ab2 of the material of the second lens (L2), the Abbe number Ab3 of the material of the third lens (L3), and the Abbe number Ab4 of the material of the fourth lens (L4) respectively satisfy the following relationships: Ab2≥70; Ab3≥70; Ab4≥65.

5. The zoom lens according to claim 1, wherein: The image side surfaces of the fifth lens (L5) and the sixth lens (L6) are both concave; The object-side surface and the image-side surface of the seventh lens (L7) are both concave; The object-side surface and the image-side surface of the eighth lens (L8) are both convex.

6. The zoom lens according to claim 1, wherein: The seventh lens (L7) and the eighth lens (L8) are cemented together to form a doublet lens.

7. The zoom lens according to claim 1, wherein: The material Abbe number Ab7 of the seventh lens (L7) satisfies the relationship: Ab7≥70.

8. The zoom lens according to claim 1, wherein: Along the direction from the object side to the image side of the optical axis, The second fixed lens group (G3) includes, in sequence, a ninth lens (L9) with positive optical power and a tenth lens (L10) with negative optical power, a total of two lenses.

9. The zoom lens according to claim 8, wherein: The object-side surface and the image-side surface of the ninth lens (L9) are both convex.

10. The zoom lens according to claim 1, wherein: The object side surface and the image side surface of the eleventh lens (L11) are both convex; The object side surfaces of the thirteenth lens (L13) and the fourteenth lens (L14) are both convex; The image-side surface of the fifteenth lens (L15) is concave.

11. The zoom lens according to claim 1, wherein: The material Abbe number Ab of the thirteenth lens (L13) 13 Satisfy the relationship: Ab 13 ≥70.

12. The zoom lens according to claim 1, wherein: The material Abbe number Ab of the fourteenth lens (L14) 14 Satisfy the relationship: Ab 14 ≤25.

13. The zoom lens according to claim 1, wherein: Along the direction from the object side to the image side of the optical axis, The focus lens group (G5) includes, in sequence, a sixteenth lens (L16) with positive or negative optical power, a seventeenth lens (L17) with positive or negative optical power, and an eighteenth lens (L18) with positive or negative optical power, a total of three lenses.

14. The zoom lens according to any one of claims 1 to 13, characterized in that: The focal length FG1 of the first fixed lens group (G1) satisfies the relationship: 8.5≤FG1 / FW≤10.5; The focal length FG2 of the first zoom lens group (G2) satisfies the relationship: -2.5≤FG2 / FW≤-1.5; The focal length FG4 of the second zoom lens group (G4) satisfies the relationship: 4.2≤FG4 / FW≤5.0; Wherein, FW is the focal length of the zoom lens at the wide-angle end.

15. The zoom lens according to any one of claims 1 to 13, characterized in that: The zoom lens comprises at least one glass aspherical lens.

16. The zoom lens according to any one of claims 1 to 13, characterized in that: The stroke D2 of the first zoom lens group (G2) and the stroke D4 of the second zoom lens group (G4) satisfy the relationship: 1.5≤|D2 / D4|≤2.

0.

17. The zoom lens according to any one of claims 1 to 13, characterized in that: The focal length FG2 of the first zoom lens group (G2) and the focal length FG4 of the second zoom lens group (G4) satisfy the relationship: -0.46≤FG2 / FG4≤-0.

30.

18. The zoom lens according to any one of claims 1 to 13, characterized in that: The maximum lens diameter ΦG1 of the first fixed lens group (G1) and the total length TTL of the zoom lens satisfy the relationship: ΦG1 / TTL≤0.4.

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