Zoom lens and imaging device

Abstract

The invention relates to the field of optics, in particular to a zoom lens and an imaging device.The zoom lens is sequentially composed of a first fixed lens group with positive focal power, a zoom lens group with negative focal power, a second fixed lens group with positive focal power and a focusing lens group with positive focal power from the object plane side to the image plane side; the zoom lens group and the focusing lens group move along the main optical axis direction of the zoom lens; the zoom lens satisfies the following conditional expressions: 1.6 < fno < 1.8; 2 < ft / fw < 3; wherein fw is the focal length of the zoom lens in a wide-angle state, ft is the focal length of the zoom lens in a telescopic state, and fno is the number of apertures of the zoom lens. According to the zoom lens, the effect of the constant aperture of the small-magnification zoom lens is achieved, the focusing time of the zoom lens is shortened, the resolving power of the zoom lens is improved, and the user experience is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optics, in particular to a zoom lens and an imaging device. BACKGROUND

[0002] A zoom lens is a lens that can change the focal length within a certain range, thereby obtaining different field angles, different image sizes and different scene ranges. The zoom lens can change the shooting range by changing the focal length without changing the shooting distance, thus being very beneficial to picture composition.

[0003] At present, the existing small-magnification zoom lens usually has a small volume and a small total optical length. Thus, the aperture of the zoom lens changes greatly during shooting. When shooting scenes at different focal lengths, the brightness changes greatly, the imaging of the zoom lens is unstable, and the focusing time is long, thereby reducing the user experience. SUMMARY

[0004] The present application will solve the existing technical problems, provide a zoom lens and an imaging device, and realize the constant aperture effect of the small-magnification zoom lens on the basis of a large field angle, thereby increasing the image brightness of the zoom lens and improving the user experience.

[0005] The technical scheme provided by the present application is as follows:

[0006] A zoom lens, which comprises, from the object side to the image side, a first fixed lens group with positive refractive power, a variable magnification lens group with negative refractive power, a second fixed lens group with positive refractive power, and a focusing lens group with positive refractive power.

[0007] The variable magnification lens group and the focusing lens group move along the main optical axis direction of the zoom lens.

[0008] The zoom lens satisfies the following conditional expression:

[0009] 1.6 < fno < 1.8;

[0010] 2 < ft / fw < 3;

[0011] Wherein, fw is the focal length of the zoom lens in the wide-angle state, ft is the focal length of the zoom lens in the telephoto state, and fno is the aperture number of the zoom lens.

[0012] Through the above structure and parameter limitation, the constant aperture effect of the small-magnification zoom lens is realized, the focusing time of the zoom lens is reduced, the resolving power of the zoom lens is increased, and the user experience is improved.

[0013] Preferably, the first fixed lens group sequentially comprises, from the object side to the image side, a first fixed lens with negative focal power, a second fixed lens with positive focal power, and a third fixed lens with positive focal power; the first fixed lens and the second fixed lens are cemented.

[0014] Preferably, the variable magnification lens group sequentially comprises, from the object side to the image side, a first variable magnification lens with negative focal power, a second variable magnification lens with negative focal power, a third variable magnification lens with positive focal power, and a fourth variable magnification lens with negative focal power; the second variable magnification lens and the third variable magnification lens are cemented.

[0015] Preferably, the second fixed lens group sequentially comprises, from the object side to the image side, a fourth fixed lens with positive focal power, a fifth fixed lens with negative focal power, a sixth fixed lens with positive focal power, a seventh fixed lens with negative focal power, and an eighth fixed lens with positive focal power; the sixth fixed lens, the seventh fixed lens, and the eighth fixed lens together form a three-cemented lens.

[0016] Preferably, the second fixed lens group sequentially comprises, from the object side to the image side, a fifth fixed lens with negative focal power, a sixth fixed lens with positive focal power, a seventh fixed lens with negative focal power, and an eighth fixed lens with positive focal power; the sixth fixed lens, the seventh fixed lens, and the eighth fixed lens together form a three-cemented lens.

[0017] Preferably, the focusing lens group sequentially comprises, from the object side to the image side, a first focusing lens with positive focal power, a second focusing lens with negative focal power, a third focusing lens with positive focal power, a fourth focusing lens with negative focal power, a fifth focusing lens with positive focal power, and a sixth focusing lens with negative focal power; the first focusing lens and the second focusing lens are cemented, and the third focusing lens and the fourth focusing lens are cemented.

[0018] Preferably, the second fixed lens group and / or the focusing lens group comprises an aspherical lens.

[0019] In the technical solution, the use of the aspherical lens reduces the number of lenses in the zoom lens, thereby reducing the size of the zoom lens.

[0020] Preferably, the variable magnification lens group satisfies the following conditional expression:

[0021] 1 < XG2 / fw < 2;

[0022] wherein XG2 is the maximum movement distance of the variable magnification lens group.

[0023] In the technical solution, by limiting the above parameters, the size of the zoom lens is reduced to a certain extent on the basis of realizing a small magnification of the zoom lens, thereby realizing the miniaturization of the zoom lens.

[0024] Preferably, the focusing lens group satisfies the following conditional expression:

[0025] 15 < XG2 / XG4 < 25;

[0026] Wherein, XG4 is the maximum moving distance of the focusing lens group.

[0027] In the technical solution, by limiting the above parameters, the maximum moving distance of the focusing lens group is reduced to some extent, so that the focal length of the zoom lens can be adjusted, and the zoom lens can be miniaturized.

[0028] Preferably, the zoom lens satisfies the following conditional expression:

[0029] DG24 / LG24m > 0.7;

[0030] Wherein, DG24 is the sum of the lens thicknesses of all lenses in the second fixed lens group to the focusing lens group, and LG24m is the minimum optical total length of the second fixed lens group to the focusing lens group.

[0031] In the technical solution, by limiting the thickness of the group in the zoom lens, the gap in the second fixed lens group to the focusing lens group is reduced, the space utilization in the zoom lens is increased, and the zoom lens is miniaturized.

[0032] One of the purposes of the present application is also to provide an imaging device, comprising: a zoom lens; and an imaging element configured to receive an image formed by the zoom lens.

[0033] Compared with the prior art, the zoom lens and the imaging device provided by the present application have the following beneficial effects:

[0034] 1. The present application realizes the constant aperture effect of the small magnification zoom lens, reduces the focusing time of the zoom lens, increases the resolving power of the zoom lens, and increases the user experience.

[0035] 2. By limiting the above parameters, the maximum moving distance of the focusing lens group is reduced to some extent, so that the focal length of the zoom lens can be adjusted, and the zoom lens can be miniaturized.

[0036] 3. By limiting the thickness of the group in the zoom lens, the gap in the second fixed lens group to the focusing lens group is reduced, the space utilization in the zoom lens is increased, and the zoom lens is miniaturized. BRIEF DESCRIPTION OF DRAWINGS

[0037] The above characteristics, technical features, advantages and implementation modes of the zoom lens and the imaging device will be further described in a clear and easy-to-understand manner in combination with the preferred embodiments and the accompanying drawings.

[0038] Figure 1 is a structural schematic diagram of a zoom lens according to the present application;

[0039] Figure 2 is an aberration diagram of the zoom lens according to the present application in a wide-angle state;

[0040] Figure 3 is a coma diagram of the zoom lens according to the present application in a wide-angle state;

[0041] Figure 4 is an aberration diagram of the zoom lens according to the present application in a telephoto state;

[0042] Figure 5 is a coma diagram of the zoom lens according to the present application in a telephoto state;

[0043] Figure 6 is a structural schematic diagram of another zoom lens according to the present application;

[0044] Figure 7 is an aberration diagram of the zoom lens according to the present application in a wide-angle state;

[0045] Figure 8 is a coma diagram of the zoom lens according to the present application in a wide-angle state;

[0046] Figure 9 is an aberration diagram of the zoom lens according to the present application in a telephoto state;

[0047] Figure 10 is a coma diagram of the zoom lens according to the present application in a telephoto state.

[0048] BRIEF DESCRIPTION OF DRAWINGS G1, first fixed lens group; G2, variable magnification lens group; G3, second fixed lens group; G4, focusing lens group; G5, auxiliary component; a1, first fixed lens; a2, second fixed lens; a3, third fixed lens; a4, fourth fixed lens; a5, fifth fixed lens; a6, sixth fixed lens; a7, seventh fixed lens; a8, eighth fixed lens; b1, first variable magnification lens; b2, second variable magnification lens; b3, third variable magnification lens; b4, fourth variable magnification lens; c1, first focusing lens; c2, second focusing lens; c3, third focusing lens; c4, fourth focusing lens; c5, fifth focusing lens; c6, sixth focusing lens; STO, stop; CG1, first protective glass; CG2, second protective glass. DETAILED DESCRIPTION

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] To keep the drawings concise, each figure only schematically shows the parts relevant to the invention, and these do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some figures, only one of components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0051] Example 1

[0052] like Figure 1 and Figure 6 As shown, a zoom lens is composed of a first fixed lens group G1 with positive optical power, a zoom lens group G2 with negative optical power, a second fixed lens group G3 with positive optical power, and a focusing lens group G4 with positive optical power, arranged sequentially from the object plane side to the image plane side.

[0053] The zoom lens group G2 and the focusing lens group G4 move along the main optical axis of the zoom lens.

[0054] The zoom lens satisfies the following condition:

[0055] 1.6 < fno < 1.8;

[0056] 2 < ft / fw < 3;

[0057] Where fw is the focal length of the zoom lens in wide-angle mode, ft is the focal length of the zoom lens in telephoto mode, and fno is the aperture number of the zoom lens.

[0058] By limiting the structure and parameters described above, a constant aperture effect is achieved for a low-magnification zoom lens, reducing the focusing time of the zoom lens, increasing the resolution of the zoom lens, and improving the user experience.

[0059] The first fixed lens group G1 consists of a first fixed lens a1 with negative optical power, a second fixed lens a2 with positive optical power, and a third fixed lens a3 with positive optical power, arranged sequentially from the object plane side to the image plane side; the first fixed lens a1 and the second fixed lens a2 are cemented together.

[0060] The variable magnification lens group G2 is composed of a first variable magnification lens b1 with negative focal power, a second variable magnification lens b2 with negative focal power, a third variable magnification lens b3 with positive focal power, and a fourth variable magnification lens b4 with negative focal power in order from the object side to the image side, and the second variable magnification lens b2 and the third variable magnification lens b3 are cemented.

[0061] The second fixed lens group G3 is composed of a fourth fixed lens a4 with positive focal power, a fifth fixed lens a5 with negative focal power, a sixth fixed lens a6 with positive focal power, a seventh fixed lens a7 with negative focal power, and an eighth fixed lens a8 with positive focal power in order from the object side to the image side; the sixth fixed lens a6, the seventh fixed lens a7, and the eighth fixed lens a8 together form a three-cemented lens.

[0062] Or

[0063] The second fixed lens group G3 is composed of a fifth fixed lens a5 with negative focal power, a sixth fixed lens a6 with positive focal power, a seventh fixed lens a7 with negative focal power, and an eighth fixed lens a8 with positive focal power in order from the object side to the image side; the sixth fixed lens a6, the seventh fixed lens a7, and the eighth fixed lens a8 together form a three-cemented lens.

[0064] The focusing lens group G4 is composed of a first focusing lens c1 with positive focal power, a second focusing lens c2 with negative focal power, a third focusing lens c3 with positive focal power, a fourth focusing lens c4 with negative focal power, a fifth focusing lens c5 with positive focal power, and a sixth focusing lens c6 with negative focal power in order from the object side to the image side; the first focusing lens c1 and the second focusing lens c2 are cemented, and the third focusing lens c3 and the fourth focusing lens c4 are cemented.

[0065] The second fixed lens group G3 and / or the focusing lens group G4 comprises an aspherical lens.

[0066] By using the aspherical lens, the number of lenses in the zoom lens is reduced, and thus the volume of the zoom lens is reduced.

[0067] The variable magnification lens group G2 satisfies the following conditional expression:

[0068] 1 < XG2 / fw < 2;

[0069] Wherein, XG2 is the maximum moving distance of the variable magnification lens group G2.

[0070] By limiting the above parameters, on the basis of realizing small magnification of the zoom lens, the volume of the zoom lens is reduced to a certain extent, and the miniaturization of the zoom lens is realized.

[0071] The focusing lens group G4 satisfies the following conditional expression:

[0072] 15 < XG2 / XG4 < 25;

[0073] XG4 is the maximum moving distance of the focusing lens group G4.

[0074] By limiting the above parameters, by reducing the maximum moving distance of the focusing lens group G4 to some extent, the adjustment of the focal length of the zoom lens can be realized, and the miniaturization of the zoom lens can also be realized.

[0075] The zoom lens satisfies the following conditional expression:

[0076] DG24 / LG24m > 0.7;

[0077] DG24 is the sum of the thicknesses of all lenses in the second fixed lens group G3 to the focusing lens group G4, and LG24m is the minimum total optical length of the second fixed lens group G3 to the focusing lens group G4.

[0078] By limiting the thickness of the group in the zoom lens, the gap in the second fixed lens group G3 to the focusing lens group G4 is reduced, the space utilization in the zoom lens is increased, and the miniaturization of the zoom lens is realized.

[0079] Embodiment 2

[0080] As shown in Figures 1 to 5 A zoom lens, the zoom lens is composed of a first fixed lens group G1 with positive focal power, a variable magnification lens group G2 with negative focal power, a second fixed lens group G3 with positive focal power, a focusing lens group G4 with positive focal power and an auxiliary assembly G5 from the object side to the image side in order;

[0081] The variable magnification lens group G2 and the focusing lens group G4 move along the direction of the main optical axis of the zoom lens.

[0082] The first fixed lens group G1 is composed of a first fixed lens a1 with negative focal power, a second fixed lens a2 with positive focal power and a third fixed lens a3 with positive focal power from the object side to the image side in order; the first fixed lens a1 and the second fixed lens a2 are cemented.

[0083] The variable magnification lens group G2 is composed of a first variable magnification lens b1 with negative focal power, a second variable magnification lens b2 with negative focal power, a third variable magnification lens b3 with positive focal power and a fourth variable magnification lens b4 with negative focal power from the object side to the image side in order, and the second variable magnification lens b2 and the third variable magnification lens b3 are cemented.

[0084] The second fixed lens group G3 is composed of a fourth fixed lens a4 with positive refractive power, a fifth fixed lens a5 with negative refractive power, a sixth fixed lens a6 with positive refractive power, a seventh fixed lens a7 with negative refractive power, and an eighth fixed lens a8 with positive refractive power, sequentially from the object side to the image side; the sixth fixed lens a6, the seventh fixed lens a7, and the eighth fixed lens a8 together form a triplet.

[0085] The focusing lens group G4 is composed of a first focusing lens c1 with positive refractive power, a second focusing lens c2 with negative refractive power, a third focusing lens c3 with positive refractive power, a fourth focusing lens c4 with negative refractive power, a fifth focusing lens c5 with positive refractive power, and a sixth focusing lens c6 with negative refractive power, sequentially from the object side to the image side; the first focusing lens c1 and the second focusing lens c2 are cemented, and the third focusing lens c3 and the fourth focusing lens c4 are cemented.

[0086] The auxiliary assembly G5 is composed of a first protective glass CG1 and a second protective glass CG2, sequentially from the object side to the image side.

[0087] The basic lens data of the zoom lens of the present embodiment is shown in Table 1, the variable parameters in Table 1 are shown in Table 2, and the aspheric surface coefficients are shown in Table 3.

[0088] The surface number column shows the surface number when the surface on the object side is set as the first surface and the number is increased one by one as it goes toward the image side; the surface type column shows the surface type of a certain lens; the curvature radius column shows the curvature radius of a certain lens, and the curvature radius is positive when the surface is curved toward the object side and is negative when the surface is curved toward the image side; the center thickness column shows the surface interval on the optical axis of each surface and the surface adjacent to it on the image side; the refractive index column shows the refractive index of a certain lens; and the Abbe number column shows the Abbe number of a certain lens.

[0089] In Table 2, the WIDE column shows the specific values of each variable parameter when the zoom lens is in the wide-angle end state, and the TELE column shows the specific values of each variable parameter when the zoom lens is in the telephoto end state.

[0090] In Table 3, K is the conic coefficient, e is the scientific notation number, for example, e-005 represents 10 -5 .

[0091]

Table 1

[0092]

[0093]

[0094]

Table 2

[0095] Wide TELE D1 0.6 25.59 D2 28.07 3.08 D3 2.51 1.34 D4 2.73 3.9

[0096] Table 3

[0097]

[0098] In this embodiment, fw = 16mm, ft = 39.99mm, ft / fw = 2.5; fno = 1.62~1.65, TTL = 129.99mm;

[0099] Wherein, fw is the focal length of the zoom lens in wide-angle mode, ft is the focal length of the zoom lens in telephoto mode, fno is the aperture number of the zoom lens, and TTL is the total optical length of the zoom lens.

[0100] XG2=24.99mm, XG2 / fw=1.56;

[0101] XG4=1.17mm, XG4 / XG2=21.4;

[0102] Wherein, XG2 is the maximum moving distance of the zoom lens group G2, and XG4 is the maximum moving distance of the focusing lens group G4.

[0103] DG24=49.28mm; LG24m=68.63mm; DG24 / LG24m=0.718;

[0104] Wherein, DG24 is the sum of the lens thicknesses of all lenses in the second fixed lens group G3 to the focusing lens group G4, and LG24m is the minimum total optical length of the second fixed lens group G3 to the focusing lens group G4.

[0105] Example 3

[0106] like Figures 6 to 10 As shown, a zoom lens is composed of a first fixed lens group G1 with positive optical power, a zoom lens group G2 with negative optical power, a second fixed lens group G3 with positive optical power, a focusing lens group G4 with positive optical power, and an auxiliary component G5, arranged sequentially from the object plane side to the image plane side.

[0107] The zoom lens group G2 and the focusing lens group G4 move along the main optical axis of the zoom lens.

[0108] The first fixed lens group G1 consists of a first fixed lens a1 with negative optical power, a second fixed lens a2 with positive optical power, and a third fixed lens a3 with positive optical power, arranged sequentially from the object plane side to the image plane side; the first fixed lens a1 and the second fixed lens a2 are cemented together.

[0109] The variable magnification lens group G2 is composed of, in order from the object side to the image side, a first variable magnification lens bl of negative refractive power, a second variable magnification lens b2 of negative refractive power, a third variable magnification lens b3 of positive refractive power, and a fourth variable magnification lens b4 of negative refractive power, and the second variable magnification lens b2 and the third variable magnification lens b3 are cemented.

[0110] The second fixed lens group G3 is composed of, in order from the object side to the image side, a fifth fixed lens a5 of negative refractive power, a sixth fixed lens a6 of positive refractive power, a seventh fixed lens a7 of negative refractive power, and an eighth fixed lens a8 of positive refractive power; the sixth fixed lens a6, the seventh fixed lens a7, and the eighth fixed lens a8 together constitute a three-cemented lens.

[0111] The focusing lens group G4 is composed of, in order from the object side to the image side, a first focusing lens cl of positive refractive power, a second focusing lens c2 of negative refractive power, a third focusing lens c3 of positive refractive power, a fourth focusing lens c4 of negative refractive power, a fifth focusing lens c5 of positive refractive power, and a sixth focusing lens c6 of negative refractive power; the first focusing lens cl and the second focusing lens c2 are cemented, and the third focusing lens c3 and the fourth focusing lens c4 are cemented.

[0112] The auxiliary assembly G5 is composed of, in order from the object side to the image side, a first protective glass CG1 and a second protective glass CG2.

[0113] The basic lens data of the zoom lens of the present embodiment is shown in Table 4, the variable parameters in Table 4 are shown in Table 5, and the aspheric surface coefficients are shown in Table 6.

[0114] In the surface number column, the surface numbers are shown when the surfaces on the object side are set as the first surface and the numbers are sequentially increased as they go toward the image side; in the surface type column, the surface types of certain lenses are shown; in the radius of curvature column, the radius of curvature of certain lenses is shown, and the radius of curvature is positive when the surface is curved toward the object side and is negative when the surface is curved toward the image side; in the center thickness column, the surface separation on the optical axis of each surface and the surface on its image side is shown; in the refractive index column, the refractive index of certain lenses is shown; and in the Abbe number column, the Abbe number of certain lenses is shown.

[0115] In Table 5, the specific values of each variable parameter when the zoom lens is in the wide-angle end state are shown in the WIDE column, and the specific values of each variable parameter when the zoom lens is in the telephoto end state are shown in the TELE column.

[0116] In Table 6, K is the conic coefficient, e is the scientific notation number, for example, e-005 represents 10 -5 .

[0117] [Table 4]

[0118]

[0119]

[0120] Table 5

[0121] Wide TELE D1 0.58 23.02 D2 24.57 2.13 D3 2.6 1.3 D4 2.91 4.21

[0122] Table 6

[0123]

[0124] In this embodiment, fw=16.5mm, ft=37.5mm, ft / fw=2.27; fno=1.62~1.65, TTL=130.01mm;

[0125] wherein, fw is the focal length of the wide-angle state of the zoom lens, ft is the focal length of the telephoto state of the zoom lens, fno is the aperture number of the zoom lens, and TTL is the total optical length of the zoom lens.

[0126] XG2=22.44mm, XG2 / fw=1.36;

[0127] XG4=1.3mm, XG4 / XG2=17.3;

[0128] wherein, XG2 is the maximum moving distance of the variable magnification lens group G2, and XG4 is the maximum moving distance of the focusing lens group G4.

[0129] DG24=55.89mm; LG24m=71.39mm; DG24 / LG24m=0.783;

[0130] wherein, DG24 is the sum of the thicknesses of all lenses in the second fixed lens group G3 to the focusing lens group G4, and LG24m is the minimum total optical length of the second fixed lens group G3 to the focusing lens group G4.

[0131] Embodiment 4

[0132] An imaging device, such as Figure 1 As shown in FIG. 10, the imaging device comprises the zoom lens as described in any of the above embodiments, and an imaging element configured to receive an image formed by the zoom lens.

[0133] It should be noted that the above embodiments can be freely combined as needed. The above description is only the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A zoom lens, characterized in that, The zoom lens comprises, in order from the object side to the image side, a first fixed lens group with positive refractive power, a zoom lens group with negative refractive power, a second fixed lens group with positive refractive power, and a focusing lens group with positive refractive power. The zoom lens group and the focusing lens group move along the main optical axis of the zoom lens. The zoom lens satisfies the following conditional expressions: 1.6 < fno < 1.8; 2 < ft / fw < 3; wherein fw is the focal length of the zoom lens in a wide-angle state, ft is the focal length of the zoom lens in a telephoto state, and fno is the aperture number of the zoom lens.

2. The zoom lens according to claim 1, wherein the first fixed lens group comprises, in order from the object side to the image side, a first fixed lens with negative refractive power, a second fixed lens with positive refractive power, and a third fixed lens with positive refractive power, and the first fixed lens and the second fixed lens are cemented.

3. The zoom lens according to claim 1, wherein the zoom lens group comprises, in order from the object side to the image side, a first zoom lens with negative refractive power, a second zoom lens with negative refractive power, a third zoom lens with positive refractive power, and a fourth zoom lens with negative refractive power, and the second zoom lens and the third zoom lens are cemented.

4. The zoom lens according to claim 1, wherein the second fixed lens group comprises, in order from the object side to the image side, a fourth fixed lens with positive refractive power, a fifth fixed lens with negative refractive power, a sixth fixed lens with positive refractive power, a seventh fixed lens with negative refractive power, and an eighth fixed lens with positive refractive power, and the sixth fixed lens, the seventh fixed lens, and the eighth fixed lens are cemented.

5. The zoom lens according to claim 1, wherein the second fixed lens group comprises, in order from the object side to the image side, a fifth fixed lens with negative refractive power, a sixth fixed lens with positive refractive power, a seventh fixed lens with negative refractive power, and an eighth fixed lens with positive refractive power, and the sixth fixed lens, the seventh fixed lens, and the eighth fixed lens are cemented.

6. The zoom lens according to claim 1, wherein the focusing lens group comprises, in order from the object side to the image side, a first focusing lens with positive refractive power, a second focusing lens with negative refractive power, a third focusing lens with positive refractive power, a fourth focusing lens with negative refractive power, a fifth focusing lens with positive refractive power, and a sixth focusing lens with negative refractive power, and the first focusing lens and the second focusing lens are cemented, and the third focusing lens and the fourth focusing lens are cemented.

7. The zoom lens according to claim 1, wherein the second fixed lens group and / or the focusing lens group comprises an aspherical lens.

8. The zoom lens according to claim 1, wherein the zoom lens group satisfies the following conditional expression: 1 < XG2 / fw < 2; wherein XG2 is the maximum moving distance of the zoom lens group.

9. The zoom lens according to claim 8, wherein the focusing lens group satisfies the following conditional expression: 15 < XG2 / XG4 < 25; ​ ​ ​ ​ ​ ​ ​ ​ wherein XG4 is a maximum moving distance of the focus lens group.

10. The zoom lens according to claim 1, characterized in that: the zoom lens satisfies the following conditional expression: DG24 / LG24m > 0.7; wherein DG24 is a sum of lens thicknesses of all lenses in the second fixed lens group to the focus lens group, and LG24m is a minimum optical total length from the second fixed lens group to the focus lens group.

11. An image forming apparatus characterized by comprising: comprising: the zoom lens according to any one of claims 1 to 10; and an imaging element configured to receive an image formed by the zoom lens.

Images