CN115291376B - Zoom lens - Google Patents
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- CN115291376B CN115291376B CN202211231431.XA CN202211231431A CN115291376B CN 115291376 B CN115291376 B CN 115291376B CN 202211231431 A CN202211231431 A CN 202211231431A CN 115291376 B CN115291376 B CN 115291376B
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/16—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group
- G02B15/177—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective with interdependent non-linearly related movements between one lens or lens group, and another lens or lens group having a negative front lens or group of lenses
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Abstract
The invention provides a zoom lens, which comprises four groups of lens groups in total, wherein the four groups of lens groups are sequentially arranged from an object side to an imaging surface along an optical axis as follows: the first lens group having negative power includes: a first lens having a negative power, a second lens having a negative power; the second lens group having positive optical power includes: the lens comprises a third lens with positive focal power, a diaphragm, a fourth lens with positive focal power and a fifth lens with positive focal power; the third lens group having negative power includes: a sixth lens having positive power, a seventh lens having negative power, an eighth lens having positive power; the fourth lens group having positive optical power includes: a ninth lens having positive optical power, and a tenth lens having positive optical power. The zoom lens has the advantages of large field of view, large aperture and miniaturization.
Description
Technical Field
The invention relates to the technical field of imaging lenses, in particular to a zoom lens.
Background
With the continuous advance of the technology, the requirements of consumers on security lenses are higher and higher, and on one hand, the wide-angle zoom lens is applicable to various monitoring scenes due to the variable focal length; the other party is more and more popular in the security market because of the large field angle, and the targets in a wider range can be monitored. However, the aperture of the current wide-angle zoom lens is usually not very large, and only has the maximum aperture of F1.6 to F1.8, and the focusing difficulty and the off-axis aberration correction difficulty of the wide-angle zoom lens are multiplied along with the increase of the aperture.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a zoom lens having advantages of a large field of view, a large aperture, a high pixel count, and a small size.
In order to realize the purpose, the technical scheme of the invention is as follows:
a zoom lens comprises four groups of lenses, and the four groups of lenses are as follows from an object side to an imaging surface along an optical axis:
the first lens group having negative power includes: a first lens having a negative power, a second lens having a negative power;
the second lens group having positive optical power includes: the lens comprises a third lens with positive focal power, a diaphragm, a fourth lens with positive focal power and a fifth lens with positive focal power;
the third lens group having negative power includes: a sixth lens having positive optical power, a seventh lens having negative optical power, an eighth lens having positive optical power;
the fourth lens group having positive optical power includes: a ninth lens having positive optical power, a tenth lens having positive optical power.
Preferably, the object-side surface of the first lens element is convex, and the image-side surface of the first lens element is concave; the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface.
Preferably, the effective focal length f of the zoom lens in the wide angle state W And effective focal length f in a telephoto state T Satisfies the following conditions: f. of T /f W ＜2.0。
Preferably, the effective focal length f and the total optical length TTL of the zoom lens satisfy: TTL/f is more than 10.0 and less than 22.0.
Preferably, the total optical length TTL of the zoom lens and the real image height IH corresponding to the maximum field angle satisfy: 8.5 < TTL/IH < 9.5.
Preferably, the effective focal length f of the zoom lens in the wide-angle state W Focal length f of the first lens group G1 Satisfies the following conditions: -3.0 < f G1 /f W ＜-2.0。
Preferably, a focal length f of the second lens group in a wide angle state of the zoom lens WG2 And a focal length f of the second lens group in a telephoto state TG2 Satisfies the following conditions: 1.0 < f TG2 /f WG2 ＜2.0。
Preferably, a focal length f of the third lens group in a wide angle state of the zoom lens WG3 And a focal length f of the third lens group in a telephoto state TG3 Satisfies the following conditions: f is more than 0.9 TG3 /f WG3 ＜1.1。
Preferably, the focal length f of the second lens group G2 Focal length f of the third lens group G3 Satisfies the following conditions: -4.0＜f G2 /f G3 ＜-2.0。
Preferably, the effective focal length f of the zoom lens in the wide angle state W Focal length f of the fourth lens group G4 Satisfies the following conditions: 1.0 < f G4 /f W ＜2.0。
Compared with the prior art, the invention has the beneficial effects that: the zoom lens has the advantages of large field of view, large aperture, high pixels and miniaturization through reasonable combination of the lens shapes and focal powers between the lenses.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural view of a wide-angle state of a zoom lens in embodiment 1 of the present invention;
FIG. 2 is a field curvature curve diagram of a wide-angle state of a zoom lens in embodiment 1 of the present invention;
FIG. 3 is a diagram showing F-tan θ distortion curves at a wide angle of a zoom lens in embodiment 1 of the present invention;
FIG. 4 is a MTF curve of the wide-angle state of the zoom lens in embodiment 1 of the present invention;
fig. 5 is a schematic structural view of a zoom lens in a telephoto state in embodiment 1 of the present invention;
fig. 6 is a field curvature graph of the zoom lens in a telephoto state in embodiment 1 of the present invention;
FIG. 7 is a graph showing F-tan θ distortion in a telephoto state of the zoom lens in embodiment 1 of the present invention;
FIG. 8 is a graph showing MTF curves in a telephoto state of the zoom lens in embodiment 1 of the present invention;
fig. 9 is a schematic structural view of a wide-angle state of a zoom lens in embodiment 2 of the present invention;
FIG. 10 is a field curvature curve diagram of a zoom lens in a wide angle state in embodiment 2 of the present invention;
FIG. 11 is a diagram showing F-tan θ distortion curves at a wide angle of a zoom lens in embodiment 2 of the present invention;
FIG. 12 is a MTF curve of the wide-angle state of the zoom lens in embodiment 2 of the present invention;
fig. 13 is a schematic structural view of a zoom lens in a telephoto state in embodiment 2 of the present invention;
fig. 14 is a field curvature graph of the zoom lens in a telephoto state in embodiment 2 of the present invention;
fig. 15 is a graph showing F-tan θ distortion in a telephoto state of the zoom lens in embodiment 2 of the present invention;
fig. 16 is an MTF graph in the telephoto state of the zoom lens in embodiment 2 of the present invention;
fig. 17 is a schematic structural view of a wide-angle state of a zoom lens in embodiment 3 of the present invention;
FIG. 18 is a field curvature diagram of a wide-angle state of a zoom lens in embodiment 3 of the present invention;
FIG. 19 is a diagram showing F-tan θ distortion curves at a wide angle of a zoom lens in embodiment 3 of the present invention;
FIG. 20 is a MTF graph of the wide-angle state of the zoom lens in embodiment 3 of the present invention;
fig. 21 is a schematic structural view of a zoom lens in a telephoto state in embodiment 3 of the present invention;
fig. 22 is a field curvature graph of the zoom lens in a telephoto state in embodiment 3 of the present invention;
fig. 23 is a graph showing F-tan θ distortion in a telephoto state of the zoom lens in embodiment 3 of the present invention;
fig. 24 is an MTF graph in a telephoto state of the zoom lens in embodiment 3 of the present invention;
fig. 25 is a schematic structural view of a wide-angle state of a zoom lens in embodiment 4 of the present invention;
FIG. 26 is a field curvature diagram of a wide-angle state of a zoom lens in embodiment 4 of the present invention;
FIG. 27 is a diagram showing F-tan θ distortion curves at a wide angle of a zoom lens in embodiment 4 of the present invention;
FIG. 28 is a MTF curve of the wide-angle state of the zoom lens in embodiment 4 of the present invention;
fig. 29 is a schematic configuration diagram of a telephoto state of the zoom lens in embodiment 4 of the present invention;
fig. 30 is a field curvature graph in a telephoto state of the zoom lens in embodiment 4 of the present invention;
fig. 31 is a graph showing F-tan θ distortion in a telephoto state of the zoom lens in embodiment 4 of the present invention;
fig. 32 is a MTF graph showing the telephoto state of the zoom lens in embodiment 4 of the present invention.
The following detailed description will further illustrate the invention in conjunction with the above-described figures.
Detailed Description
For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of embodiments of the application and does not limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in this specification the expressions first, second, third etc. are only used to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present invention.
In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.
Herein, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.
It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to examples or illustrations.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
The zoom lens according to the embodiment of the present invention includes, in order from an object side to an image side: the lens comprises a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a third lens group G3 with negative focal power, a fourth lens group G4 with positive focal power, a filter A1 and protective glass A2.
The first lens group G1 includes: the first lens with negative focal power has a convex object-side surface and a concave image-side surface; the second lens with negative focal power has a concave object-side surface and a convex image-side surface.
The second lens group G2 includes: the third lens with positive focal power has a convex object-side surface and a convex image-side surface; a diaphragm ST; a fourth lens element with positive refractive power having a concave object-side surface and a convex image-side surface; and the image side surface of the fifth lens with positive focal power is convex.
The third lens group G3 includes: a sixth lens element having a positive refractive power, wherein both the object-side surface and the image-side surface are convex; a seventh lens element having a negative refractive power, both the object-side surface and the image-side surface of which are concave surfaces; the eighth lens element with positive refractive power has a convex object-side surface and a concave image-side surface.
The fourth lens group G4 includes: a ninth lens having a positive refractive power, both the object-side surface and the image-side surface of which are convex surfaces; the tenth lens with positive focal power has a convex object-side surface and a concave image-side surface.
The second lens group G2 can move along the optical axis and is used for realizing optical zooming of the zoom lens between a wide angle state and a telephoto state; the third lens group G3 can move along the optical axis and is used for compensating the change of the image surface position of the zoom lens in the optical zooming process.
In some embodiments, a diaphragm for limiting light beams can be arranged between the third lens and the fourth lens, so that ghost images of the zoom lens can be reduced, light rays entering the optical system can be converged, and the rear end aperture of the zoom lens can be reduced; moreover, the diaphragm is arranged at the position, so that the zoom lens has a larger aperture, and the performance requirement of the zoom lens for the large aperture is met.
In some embodiments, the effective focal length f in the wide angle state of the zoom lens W And effective focal length f in a telephoto state T Satisfies the following conditions: f. of T /f W Is less than 2.0. The zoom lens meets the range, is beneficial to realizing continuous zooming, and ensures that the zoom lens has good imaging quality in different scenes.
In some embodiments, the maximum field angle FOV at the wide angle state of the zoom lens W Satisfies the following conditions: FOV not more than 90 DEG W (ii) a Maximum field angle FOV of zoom lens in focus T Satisfies the following conditions: FOV (field of View) T Less than or equal to 46 degrees. The method meets the range, and can meet the requirement on the mainstream field angle in the security monitoring application scene.
In some embodiments, the effective focal length f and the total optical length TTL of the zoom lens satisfy: TTL/f is more than 10.0 and less than 22.0. The zoom lens can effectively limit the length of the zoom lens and realize the miniaturization of the zoom lens.
In some embodiments, the total optical length TTL of the zoom lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is more than 8.5 and less than 9.5. The zoom lens meets the range, the total length of the zoom lens is favorably shortened while good imaging quality is considered, the zoom lens is miniaturized, and the requirements of miniaturization and large image surface in a security monitoring application scene are met.
In some embodiments, total optical length TTL of wide angle state of zoom lens W And optical back focus BFL satisfies: BFL/TTL is more than 0.02 W . The method meets the range, is favorable for obtaining balance between good imaging quality and easy-to-assemble optical back focal length, and reduces the difficulty of the camera module assembly process while ensuring the imaging quality of the zoom lens.
In some embodiments, the effective focal length f in the wide-angle state of the zoom lens W Focal length f of the first lens group G1 G1 Satisfies the following conditions: -3.0 < f G1 /f W < -2.0. Satisfy above-mentioned scope, through the focus of each lens of rational distribution first battery of lens G1, can effectively avoid the outer light of visual field to reach the imaging surface, promote zoom's imaging quality.
In some embodiments, the focal length f of the second lens group G2 of the zoom lens G2 Focal length f of the third lens group G3 G3 Satisfies the following conditions: -4.0 < f G2 /f G3 < -2.0. The zoom lens has the advantages that the range is met, various aberrations of the zoom lens can be effectively balanced through reasonably distributing the focal lengths of the second lens group and the third lens group, and the imaging quality of the zoom lens is improved.
In some embodiments, the effective focal length f in the wide angle state of the zoom lens W Focal length f of fourth lens group G4 G4 Satisfies the following conditions: 1.0 < f G4 /f W Is less than 2.0. Satisfying the above range, the zoom lens can be effectively corrected by reasonably distributing the focal lengths of the lenses of the fourth lens groupAnd various aberrations improve the imaging quality of the zoom lens.
In some embodiments, the effective focal length f in the wide-angle state of the zoom lens W Distance CT on optical axis from the first lens group G1 and the second lens group G2 1 Satisfies the following conditions: CT of 4.0 < 1 /f W Is less than 5.5. Satisfying the above range, the length of the zoom lens can be effectively limited, and the zoom lens can be miniaturized.
In some embodiments, the effective focal length f in the telephoto state of the zoom lens t Distance CT on optical axis from the second lens group G2 and the third lens group G3 3 Satisfies the following conditions: 1.45 < CT 3 /f t Is less than 1.65. Satisfying the above range, the length of the zoom lens can be effectively limited, and the zoom lens can be miniaturized.
In order to enable the system to have better optical performance, a plurality of aspheric lenses are adopted in the lens, and the surface shapes of the aspheric surfaces of the zoom lens satisfy the following equation:
wherein z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance between the optical axis and the curved surface, c is the curvature of the vertex of the curved surface, K is the coefficient of the quadric surface, and A, B, C, D, E, F, G, H are the coefficients of the second order, the fourth order, the sixth order, the eighth order, the tenth order, the twelfth order, the fourteenth order and the sixteenth order curved surfaces respectively.
The invention is further illustrated below in the following examples. In various embodiments, the thickness, the curvature radius, and the material selection part of each lens in the zoom lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the innovative points of the present invention should be construed as being equivalent substitutions and shall be included within the scope of the present invention.
Example 1
Referring to fig. 1 and fig. 5, there are shown schematic structural diagrams of a zoom lens according to embodiment 1 of the present invention, the zoom lens sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a third lens group G3 with negative focal power, a fourth lens group G4 with positive focal power, an optical filter A1 and protective glass A2.
The first lens group G1 includes: a first lens element L1 having a negative refractive power, wherein an object-side surface S1 is a convex surface, and an image-side surface S2 is a concave surface; the second lens element L2 with negative refractive power has a concave object-side surface S3 and a convex image-side surface S4.
The second lens group G2 includes: a third lens L3 with positive focal power, wherein the object side surface S5 and the image side surface S6 are convex surfaces; a diaphragm ST; a fourth lens element L4 having a positive refractive power, the object-side surface S7 being concave and the image-side surface S8 being convex; the fifth lens element L5 having positive refractive power has a concave object-side surface S9 and a convex image-side surface S10.
The third lens group G3 includes: a sixth lens L6 having positive refractive power, both of the object-side surface S11 and the image-side surface S12 being convex; a seventh lens L7 having a negative refractive power, the object-side surface S13 and the image-side surface S14 of which are both concave; the eighth lens element L8 having positive refractive power has a convex object-side surface S15 and a concave image-side surface S16.
The fourth lens group G4 includes: a ninth lens L9 having positive refractive power, both of which have convex object-side surfaces S17 and image-side surfaces S18; the tenth lens L10 having positive refractive power has a convex object-side surface S19 and a concave image-side surface S20.
The second lens group G2 can move along the optical axis and is used for realizing the optical zooming of the zoom lens between a wide-angle state and a long-focus state, and the third lens group G3 can move along the optical axis and is used for compensating the change of the image surface position of the zoom lens in the optical zooming process;
the object side surface S21 and the image side surface S22 of the optical filter A1 are both planes;
the object side surface S23 and the image side surface S24 of the protective glass A2 are both planes;
the image forming surface S25 is a plane.
Relevant parameters of each lens in the zoom lens in embodiment 1 are shown in table 1-1.
TABLE 1-1
The surface shape parameters of the aspherical lens of the zoom lens in embodiment 1 are shown in tables 1 to 2.
Tables 1 to 2
The variable pitch values of the zoom lens in embodiment 1 are shown in tables 1 to 3.
Tables 1 to 3
Fig. 2 shows a field curvature curve in a wide-angle state of the zoom lens in example 1, which shows the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, the horizontal axis shows a shift amount (unit: mm), and the vertical axis shows a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within +/-0.06 mm, which shows that the field curvature can be well corrected in the wide-angle state of the zoom lens.
Fig. 3 shows an F-tan θ distortion curve in the wide-angle state of the zoom lens in example 1, which shows F-tan θ distortions at different image heights of light rays of different wavelengths on the image forming surface, the abscissa axis shows F-tan θ distortion (unit:%) and the ordinate axis shows half field angle (unit:%). As can be seen from the figure, the distortion of F-tan theta of the zoom lens is controlled within +/-16%, and the fact that the distortion of F-tan theta can be well corrected in the wide-angle state of the zoom lens is demonstrated.
Fig. 4 shows a MTF (modulation transfer function) graph of the wide-angle state of the zoom lens in embodiment 1, which represents the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly reduced in the process from the center to the edge field of view, and the image quality and the detail resolution capability are good under the conditions of low frequency and high frequency.
Fig. 6 shows a field curvature curve in a telephoto state of the zoom lens in embodiment 1, which represents the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane, the horizontal axis represents a shift amount (unit: mm), and the vertical axis represents a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.10 mm, which shows that the field curvature can be well corrected in the telephoto state of the zoom lens.
Fig. 7 shows an F-tan θ distortion curve showing F-tan θ distortion at different image heights on the image forming plane for light rays of different wavelengths in the focal state of the zoom lens in example 1, with the abscissa showing F-tan θ distortion (unit:%) and the ordinate showing half field angle (unit:%). As can be seen from the figure, the distortion of F-tan theta of the zoom lens is controlled within +/-35%, which shows that the zoom lens can better correct the distortion of F-tan theta in a long focal state.
Fig. 8 is a graph showing MTF (modulation transfer function) curves in the telephoto state of the zoom lens in embodiment 1, which shows the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis showing the spatial frequency (unit: lp/mm) and the vertical axis showing the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve decreases uniformly and smoothly in the process from the center to the edge field of view, and has good imaging quality and good detail resolution capability in both low frequency and high frequency.
Example 2
Referring to fig. 9 and 13, there are shown schematic structural diagrams of a zoom lens according to embodiment 2 of the present invention, the zoom lens sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a third lens group G3 with negative focal power, a fourth lens group G4 with positive focal power, a filter A1 and protective glass A2.
The first lens group G1 includes: a first lens element L1 having a negative refractive power, wherein an object-side surface S1 is a convex surface, and an image-side surface S2 is a concave surface; the second lens element L2 with negative refractive power has a concave object-side surface S3 and a convex image-side surface S4.
The second lens group G2 includes: a third lens L3 with positive focal power, wherein the object side surface S5 and the image side surface S6 are convex surfaces; a diaphragm ST; a fourth lens element L4 having a positive refractive power, the object-side surface S7 being concave and the image-side surface S8 being convex; the fifth lens element L5 having positive refractive power has a concave object-side surface S9 and a convex image-side surface S10.
The third lens group G3 includes: a sixth lens L6 having positive refractive power, both of the object-side surface S11 and the image-side surface S12 being convex; a seventh lens L7 having a negative refractive power, the object-side surface S13 and the image-side surface S14 of which are both concave; the eighth lens element L8 having positive refractive power has a convex object-side surface S15 and a concave image-side surface S16.
The fourth lens group G4 includes: a ninth lens L9 having positive refractive power, both of which have convex object-side surfaces S17 and image-side surfaces S18; the tenth lens L10 having positive refractive power has a convex object-side surface S19 and a concave image-side surface S20.
The second lens group G2 can move along the optical axis and is used for realizing the optical zooming of the zoom lens between a wide-angle state and a long-focus state, and the third lens group G3 can move along the optical axis and is used for compensating the change of the image surface position of the zoom lens in the optical zooming process.
Relevant parameters of each lens in the zoom lens in embodiment 2 are shown in table 2-1.
TABLE 2-1
The surface shape parameters of the aspherical lens of the zoom lens in embodiment 2 are shown in table 2-2.
Tables 2 to 2
The variable pitch values of the zoom lens in embodiment 2 are shown in tables 2 to 3.
Tables 2 to 3
Fig. 10 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in a wide-angle state of the zoom lens in example 2, in which the horizontal axis shows a shift amount (unit: mm) and the vertical axis shows a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within +/-0.10 mm, which shows that the field curvature can be well corrected in the wide-angle state of the zoom lens.
Fig. 11 shows an F-tan θ distortion curve in the wide-angle state of the zoom lens in example 2, which shows F-tan θ distortions at different image heights of light rays of different wavelengths on the image forming surface, the abscissa axis shows F-tan θ distortion (unit:%) and the ordinate axis shows half field angle (unit:%). As can be seen from the figure, the F-tan θ distortion of the zoom lens is controlled within ± 16%, which shows that the wide angle state of the zoom lens can correct the F-tan θ distortion well.
Fig. 12 shows a MTF (modulation transfer function) graph of the wide-angle state of the zoom lens in embodiment 2, which represents the lens imaging modulation degree of different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good in both the low frequency and the high frequency.
Fig. 14 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in the telephoto state and in the sagittal image plane in example 2, with the horizontal axis showing the amount of displacement (unit: mm) and the vertical axis showing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.12 mm, which shows that the field curvature can be better corrected in the zoom lens long-focus state.
Fig. 15 shows an F-tan θ distortion curve of the zoom lens in the telephoto state in example 2, which shows F-tan θ distortions at different image heights on the image forming plane for light rays of different wavelengths, the abscissa shows the F-tan θ distortion (unit:%), and the ordinate shows the half field angle (unit:%). As can be seen from the figure, the distortion of F-tan theta of the zoom lens is controlled within +/-35%, which shows that the zoom lens can better correct the distortion of F-tan theta in a long focal state.
Fig. 16 is a graph showing MTF (modulation transfer function) curves in the telephoto state of the zoom lens in embodiment 2, in which the horizontal axis represents spatial frequencies (unit: lp/mm) and the vertical axis represents MTF values, and the degree of modulation of lens imaging at different spatial frequencies for each field of view. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good in both the low frequency and the high frequency.
Example 3
Referring to fig. 17 and 21, there are shown schematic structural diagrams of a zoom lens according to embodiment 3 of the present invention, the zoom lens sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a third lens group G3 with negative focal power, a fourth lens group G4 with positive focal power, an optical filter A1 and protective glass A2.
The first lens group G1 includes: a first lens element L1 having a negative refractive power, wherein an object-side surface S1 is a convex surface, and an image-side surface S2 is a concave surface; the object-side surface S3 of the second lens element L2 with negative refractive power is concave, and the image-side surface S4 is convex.
The second lens group G2 includes: a third lens element L3 with positive focal power, wherein the object-side surface S5 and the image-side surface S6 are convex surfaces; a diaphragm ST; a fourth lens element L4 with positive refractive power, which has a concave object-side surface S7 and a convex image-side surface S8; the fifth lens element L5 with positive refractive power has a concave object-side surface S9 and a convex image-side surface S10.
The third lens group G3 includes: a sixth lens L6 having positive refractive power, both of the object-side surface S11 and the image-side surface S12 being convex; a seventh lens L7 having a negative refractive power, the object-side surface S13 and the image-side surface S14 of which are both concave; the eighth lens element L8 having positive refractive power has a convex object-side surface S15 and a concave image-side surface S16.
The fourth lens group G4 includes: a ninth lens L9 having positive refractive power, both of which have convex object-side surfaces S17 and image-side surfaces S18; the tenth lens L10 having positive refractive power has a convex object-side surface S19 and a concave image-side surface S20.
The second lens group G2 can move along the optical axis and is used for realizing the optical zooming of the zoom lens between a wide-angle state and a long-focus state, and the third lens group G3 can move along the optical axis and is used for compensating the change of the image surface position of the zoom lens in the optical zooming process.
Relevant parameters of each lens in the zoom lens in embodiment 3 are shown in table 3-1.
TABLE 3-1
The surface shape parameters of the aspherical lens of the zoom lens in embodiment 3 are shown in table 3-2.
TABLE 3-2
The variable pitch values of the zoom lens in embodiment 3 are shown in tables 3 to 3.
Tables 3 to 3
Fig. 18 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in a wide-angle state of the zoom lens in example 3, in which the horizontal axis shows a shift amount (unit: mm) and the vertical axis shows a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within +/-0.10 mm, which shows that the field curvature can be well corrected in the wide-angle state of the zoom lens.
Fig. 19 shows F-tan θ distortion curves in a wide-angle state of the zoom lens in example 3, where F-tan θ distortion is shown at different image heights on an image forming plane for light beams of different wavelengths, the abscissa shows F-tan θ distortion (unit:%), and the ordinate shows a half field angle (unit:%). As can be seen from the figure, the F-tan θ distortion of the zoom lens is controlled within ± 16%, which shows that the wide angle state of the zoom lens can correct the F-tan θ distortion well.
Fig. 20 shows a MTF (modulation transfer function) graph of the wide-angle state of the zoom lens in embodiment 3, which represents the lens imaging modulation degree of different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. It can be seen from the figure that the MTF values of the present embodiment are both above 0.5 in the full field of view, and in the range of 0 to 160lp/mm, the MTF curves decrease uniformly and smoothly in the process from the center to the edge field of view, and have good imaging quality and good detail resolution capability in both low and high frequencies.
Fig. 22 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in the telephoto state and in the sagittal image plane in example 3, with the horizontal axis showing the amount of displacement (unit: mm) and the vertical axis showing the half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.12 mm, which shows that the field curvature can be better corrected in the zoom lens long-focus state.
Fig. 23 shows an F-tan θ distortion curve of the zoom lens in the telephoto state in example 3, which shows F-tan θ distortions at different image heights on the image forming plane for light rays of different wavelengths, the abscissa shows the F-tan θ distortion (unit:%), and the ordinate shows the half field angle (unit:%). As can be seen from the figure, the distortion of the F-tan theta of the zoom lens is controlled within +/-35%, and the zoom lens in a long focal state can better correct the distortion of the F-tan theta.
Fig. 24 is a graph showing MTF (modulation transfer function) in the telephoto state of the zoom lens in embodiment 3, which represents the lens imaging modulation degree for different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good in both the low frequency and the high frequency.
Example 4
Referring to fig. 25 and 29, there are shown schematic structural diagrams of a zoom lens according to embodiment 4 of the present invention, the zoom lens sequentially includes, from an object side to an image plane along an optical axis: the lens comprises a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a third lens group G3 with negative focal power, a fourth lens group G4 with positive focal power, a filter A1 and protective glass A2.
The first lens group G1 includes: a first lens element L1 having a negative refractive power, wherein an object-side surface S1 is a convex surface, and an image-side surface S2 is a concave surface; the second lens element L2 with negative refractive power has a concave object-side surface S3 and a convex image-side surface S4.
The second lens group G2 includes: a third lens element L3 with positive focal power, wherein the object-side surface S5 and the image-side surface S6 are convex surfaces; a diaphragm ST; a fourth lens element L4 having positive refractive power, the object-side surface S7 of which is concave and the image-side surface S8 of which is convex; the fifth lens L5 having positive refractive power has a convex object-side surface S9 and a convex image-side surface S10.
The third lens group G3 includes: a sixth lens L6 having positive refractive power, both of the object-side surface S11 and the image-side surface S12 being convex; a seventh lens L7 having a negative refractive power, the object-side surface S13 and the image-side surface S14 of which are both concave; the eighth lens element L8 having positive refractive power has a convex object-side surface S15 and a concave image-side surface S16.
The fourth lens group G4 includes: a ninth lens L9 having positive refractive power, both of which have convex object-side surfaces S17 and image-side surfaces S18; the tenth lens L10 having positive refractive power has a convex object-side surface S19 and a concave image-side surface S20.
The second lens group G2 can move along the optical axis and is used for realizing the optical zooming of the zoom lens between a wide-angle state and a long-focus state, and the third lens group G3 can move along the optical axis and is used for compensating the change of the image surface position of the zoom lens in the optical zooming process.
Relevant parameters of each lens in the zoom lens in embodiment 4 are shown in table 4-1.
TABLE 4-1
The surface shape parameters of the aspherical lens of the zoom lens in embodiment 4 are shown in table 4-2.
TABLE 4-2
The variable pitch values of the zoom lens in embodiment 4 are shown in table 4-3.
Tables 4 to 3
Fig. 26 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in a wide-angle state of the zoom lens in example 4, in which the horizontal axis shows a shift amount (unit: mm) and the vertical axis shows a half field angle (unit: °). As can be seen from the figure, the field curvature of the meridional image surface and the sagittal image surface is controlled within +/-0.10 mm, which shows that the field curvature can be well corrected in the wide-angle state of the zoom lens.
Fig. 27 shows F-tan θ distortion curves in the wide-angle state of the zoom lens in example 4, which show F-tan θ distortions at different image heights on the image forming surface for light rays of different wavelengths, with the abscissa showing F-tan θ distortion (unit:%) and the ordinate showing half field angle (unit:%). As can be seen from the figure, the F-tan θ distortion of the zoom lens is controlled within ± 16%, which shows that the wide angle state of the zoom lens can correct the F-tan θ distortion well.
Fig. 28 is a graph showing MTF (modulation transfer function) in the wide-angle state of the zoom lens in embodiment 4, which represents the degree of modulation of lens imaging at different spatial frequencies for each field of view, with the horizontal axis representing the spatial frequency (unit: lp/mm) and the vertical axis representing the MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good in both the low frequency and the high frequency.
Fig. 30 is a field curvature graph showing the degree of curvature of light rays of different wavelengths on a meridional image plane and a sagittal image plane in the telephoto state and in the half angle of field (unit: °), in example 4, on the horizontal axis and on the vertical axis, respectively. As can be seen from the figure, the field curvature of the meridional image plane and the sagittal image plane is controlled within +/-0.06 mm, which shows that the zoom lens can excellently correct the field curvature in the long-focus state.
Fig. 31 shows an F-tan θ distortion curve of a zoom lens in a telephoto state in example 4, which shows F-tan θ distortions at different image heights on an image forming plane for light rays of different wavelengths, the abscissa shows the F-tan θ distortion (unit:%), and the ordinate shows a half field angle (unit:%). As can be seen from the figure, the distortion of F-tan theta of the zoom lens is controlled within +/-35%, which shows that the zoom lens can better correct the distortion of F-tan theta in a long focal state.
Fig. 32 is a graph showing MTF (modulation transfer function) curves in the telephoto state of the zoom lens in example 4, in which the horizontal axis represents spatial frequencies (unit: lp/mm) and the vertical axis represents MTF values, and the degree of modulation of lens imaging at different spatial frequencies for each field of view. As can be seen from the figure, the MTF value of the present embodiment is above 0.5 in the whole field of view, and in the range of 0-160 lp/mm, the MTF curve is uniformly and smoothly dropped in the process from the center to the edge field of view, and the image quality and the detail resolution are good in both the low frequency and the high frequency.
Please refer to tables 5-1 and 5-2, which show the optical characteristics of the zoom lens according to the above embodiments, including the effective focal length f, total optical length TTL, aperture FNO, real image height IH, and maximum field angle FOV of the zoom lens, and the values corresponding to each conditional expression in the embodiments.
TABLE 5-1
TABLE 5-2
In summary, the zoom lens according to the embodiment of the invention achieves the advantages of large field of view, large aperture, high pixel and miniaturization by reasonably matching the lens shapes and focal power combinations among the lenses.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above embodiments only show several embodiments of the present invention, and the description is specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A zoom lens, comprising four groups of lenses, is characterized in that the zoom lens comprises, from an object side to an image plane along an optical axis:
the first lens group having negative power includes: a first lens having a negative focal power, a second lens having a negative focal power;
the second lens group having positive optical power includes: the lens comprises a third lens with positive focal power, a diaphragm, a fourth lens with positive focal power and a fifth lens with positive focal power;
the third lens group having negative power includes: a sixth lens having positive optical power, a seventh lens having negative optical power, an eighth lens having positive optical power;
the fourth lens group having positive optical power includes: a ninth lens having positive optical power, a tenth lens having positive optical power.
2. The zoom lens according to claim 1, wherein the first lens has a convex object-side surface and a concave image-side surface; the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface.
3. The zoom lens according to claim 1, wherein an effective focal length f in a wide-angle state of the zoom lens W And effective focal length f in a telephoto state T Satisfies the following conditions: f. of T /f W ＜2.0。
4. The zoom lens according to claim 1, wherein the effective focal length f and the total optical length TTL of the zoom lens satisfy: TTL/f is more than 10.0 and less than 22.0.
5. The zoom lens of claim 1, wherein the total optical length TTL of the zoom lens and the real image height IH corresponding to the maximum field angle satisfy: TTL/IH is more than 8.5 and less than 9.5.
6. The zoom lens according to claim 1, wherein an effective focal length f in a wide-angle state of the zoom lens W Focal length f of the first lens group G1 Satisfies the following conditions: -3.0 < f G1 /f W ＜-2.0。
7. The zoom lens of claim 1, wherein the zoom lens has a wide angleFocal length f of the second lens group in state WG2 And a focal length f of the second lens group in a telephoto state TG2 Satisfies the following conditions: 1.0 < f TG2 /f WG2 ＜2.0。
8. The zoom lens according to claim 1, wherein a focal length f of the third lens group in a wide angle state of the zoom lens WG3 And a focal length f of the third lens group in a telephoto state TG3 Satisfies the following conditions: f is more than 0.9 TG3 /f WG3 ＜1.1。
9. The zoom lens according to claim 1, wherein a focal length f of the second lens group G2 Focal length f of the third lens group G3 Satisfies the following conditions: -4.0 < f G2 /f G3 ＜-2.0。
10. The zoom lens according to claim 1, wherein an effective focal length f in a wide-angle state of the zoom lens W Focal length f of the fourth lens group G4 Satisfies the following conditions: 1.0 < f G4 /f W ＜2.0。
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