CN115327756A - Zoom lens - Google Patents
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- CN115327756A CN115327756A CN202211264840.XA CN202211264840A CN115327756A CN 115327756 A CN115327756 A CN 115327756A CN 202211264840 A CN202211264840 A CN 202211264840A CN 115327756 A CN115327756 A CN 115327756A
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- G—PHYSICS
- G02—OPTICS
- 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
- G02B15/143—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 having three groups only
- G02B15/1435—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 having three groups only the first group being negative
- G02B15/143507—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 having three groups only the first group being negative arranged -++
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
- G02B13/0045—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface having five or more lenses
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Abstract
The invention provides a zoom lens, which comprises three groups of lens groups in total, wherein the three groups of lens groups are as follows from an object side to an imaging surface along an optical axis in sequence: the first lens group having negative power includes: a first lens having a negative optical power; the second lens group having positive optical power includes: a second lens having negative focal power, a third lens having positive focal power; a diaphragm; the third lens group having positive optical power includes: the lens system comprises a fourth lens with negative focal power, a fifth lens with positive focal power, a sixth lens with positive focal power and a seventh lens with focal power. The zoom lens has the advantages of high imaging quality, miniaturization and easy processing.
Description
Technical Field
The invention relates to the technical field of imaging lenses, in particular to a zoom lens.
Background
With the development of smart phones, users have higher and higher requirements on the photographing level and the photographing quality of the smart phones, and in the prior art, the effect of optical zooming is achieved by setting a plurality of fixed-focus lenses and by using digital hybrid zooming and switching between the lenses. However, zooming in this way is not only less effective, but also takes up a large space and is costly. The continuous optical zooming has longer shooting distance and more real detailed embodiment, and can realize the multi-magnification focusing function and meet the shooting requirements of users in different scenes. However, such zoom lenses generally have the problems of large size, low assembly yield, low imaging quality, and the like.
Therefore, it is an urgent need to design a zoom lens with high imaging quality, small size and good processing characteristics.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a zoom lens having advantages of high imaging quality, miniaturization, and easy processing.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a zoom lens comprises three groups of lens groups, which 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 optical power;
the second lens group having positive optical power includes: a second lens having a negative refractive power, a third lens having a positive refractive power;
a diaphragm;
the third lens group having positive optical power includes: the lens system comprises a fourth lens with negative focal power, a fifth lens with positive focal power, a sixth lens with positive focal power and a seventh lens with focal power.
Preferably, both the object-side surface and the image-side surface of the first lens are concave.
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 total optical length TTL of the zoom lens in the wide-angle state W And total optical length TTL in long focus state T Satisfies the following conditions: TTL (transistor-transistor logic) T /TTL W ＜1.5。
Preferably, the total optical length TTL of the zoom lens and the real image height IH corresponding to the maximum field angle satisfy: 3.5 < TTL/IH < 5.5.
Preferably, the total optical length TTL of the zoom lens in the wide-angle state W And optical back focus BFL meets the following requirements: BFL/TTL of 0.35 < W 。
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, the effective focal length f of the zoom lens in the wide angle state W Focal length f of the second lens group G2 Satisfies the following conditions: 25 < | f G2 /f W |。
Preferably, the effective focal length f of the zoom lens in the wide angle state W Focal length f of the third lens group G3 Satisfies the following conditions: 1.0 < f G3 /f W ＜1.5。
Preferably, the effective focal length f of the second lens 2 And an effective focal length f of the third lens 3 Satisfies the following conditions: -1.2 < f 2 /f 3 ＜-0.8。
Compared with the prior art, the invention has the beneficial effects that: the zoom lens has the advantages of being high in imaging quality, small in size and easy to machine through reasonable matching of the lens shape and the focal power combination among 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 diagram 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 an MTF graph 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 diagram of a wide-angle state of a zoom lens in embodiment 2 of the present invention;
FIG. 11 is a graph showing the F-tan θ distortion at the wide angle of the zoom lens in embodiment 2 of the present invention;
FIG. 12 is a MTF curve diagram 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 a 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 configuration diagram of a telephoto state of the zoom lens in embodiment 3 of the present invention;
fig. 22 is a field curvature graph in a telephoto state of the zoom lens 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 a graph showing MTF in the telephoto state of the zoom lens in embodiment 3 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, the use of "may" mean "one or more embodiments of the application" when describing embodiments of the application. Also, the term "exemplary" is intended to refer to an example or illustration.
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 the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
The zoom lens according to the embodiment of the present invention includes, in order from an object side to an image side: a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a diaphragm ST, a third lens group G3 with positive focal power and a filter A1.
The first lens group G1 includes: the first lens with negative focal power has a concave object-side surface and a concave image-side surface.
The second lens group G2 includes: a second lens with negative focal power, wherein the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the third lens with positive focal power has a convex object-side surface and a concave image-side surface.
The third lens group G3 includes: a fourth lens with negative focal power, wherein the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a concave surface; a fifth lens element having a positive refractive power, the object-side surface and the image-side surface of the fifth lens element being convex; a sixth lens element having a positive refractive power, the object-side surface of which is concave and the image-side surface of which is convex; and the seventh lens with the 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 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.
In some embodiments, a stop for limiting light beams may be disposed between the second lens group G2 and the third lens group G3, so as to reduce ghost images of the zoom lens, facilitate converging light rays entering the optical system, and reduce the rear aperture of the zoom lens.
In some embodiments, the effective focal length f of 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 increasing the field angle difference of the zoom lens, reduces distortion 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 of 43 degrees or less W (ii) a Maximum field angle FOV of zoom lens in focus T Satisfies the following conditions: FOV (field of View) T Is less than or equal to 23 degrees. The range is met, the shooting requirement for a remote object can be met, and the background highlighting focusing main body is effectively virtualized.
In some embodiments, the aperture value FNO of the zoom lens satisfies: FNO is more than 1.85 and less than 3.85. Satisfying the above range is advantageous for realizing large aperture characteristics, and especially, ensuring the clarity of the image while realizing blurring foreground and background in a telephoto state.
In some embodiments, total optical length TTL of wide angle state of zoom lens W And total optical length TTL in long focus state T Satisfies the following conditions: TTL (transistor-transistor logic) T /TTL W Is less than 1.5. Satisfying the above range, zooming can be effectively restrictedThe length of the lens realizes 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 3.5 and less than 5.5. The zoom lens meets the range, is favorable for shortening the total length of the zoom lens while giving consideration to good imaging quality, and meets the requirements of miniaturization and large image surface of the zoom lens.
In some embodiments, total optical length TTL of wide angle state of zoom lens W And optical back focus BFL meets the following requirements: BFL/TTL of 0.35 < W . The method meets the range, is favorable for balancing the good imaging quality and the optical back focal length easy to assemble, ensures the imaging quality of the zoom lens, and reduces the difficulty of the camera module assembly process.
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 Satisfies the following conditions: -3.0 < f G1 /f W < -2.0. Satisfy above-mentioned scope, through the focus of rational distribution first battery of lens, can effectively avoid the outer light of visual field to reach the imaging surface, promote zoom's imaging quality.
In some embodiments, the effective focal length f in the wide-angle state of the zoom lens W Focal length f of the second lens group G2 Satisfies the following conditions: 25 < | f G2 /f W L. Satisfy above-mentioned scope, can be in charge of the focus control of the second lens group of the function of zooming in great scope, can make light can be gentle enter into the third lens group from the second lens group, promote zoom's the imaging quality.
In some embodiments, the effective focal length f in the wide angle state of the zoom lens W Focal length f of the third lens group G3 Satisfies the following conditions: 1.0 < f G3 /f W Is less than 1.5. Satisfying the above range, the focal length of the third lens group responsible for the compensation function can be controlled within a small range, which is advantageous for achieving stable zooming of the zoom lens between the wide angle state and the telephoto state.
In some embodiments, the effective focal length f of the second lens 2 And the effective focal length f of the third lens 3 Satisfies the following conditions: -1.2 < f 2 /f 3 < -0.8. The zoom lens meets the range, is favorable for balancing the spherical aberration and the curvature of field of the second lens group, and improves the imaging quality of the zoom lens.
In some embodiments, the effective focal length f of the zoom lens and the distance CT on the optical axis between the first lens group and the second lens group 1 Satisfies the following conditions: 0 < CT 1 The/f is less than 0.8. 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 of the zoom lens is equal to the distance CT on the optical axis between the second lens group and the third lens group 3 Satisfies the following conditions: 0 < CT 3 The/f is less than 0.9. The zoom lens can effectively limit the length of the zoom lens and realize the miniaturization of the zoom lens.
In order to enable the system to have better optical performance, a plurality of aspheric lenses are adopted in the lens, and the 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 direction of the optical axis, 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, I and J 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, the sixteenth order, the eighteenth order and the twentieth order.
The invention is further illustrated below in the following examples. In the various embodiments, the thickness, the curvature radius, and the material selection part of each lens in the zoom lens are different, and specific differences can be referred to the parameter tables of the various embodiments. The following examples are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the following examples, and any other changes, substitutions, combinations or simplifications which do not depart from the gist of the present invention should be construed as being equivalent replacements 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: a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a diaphragm ST, a third lens group G3 with positive focal power and a filter A1.
The first lens group G1 includes: the object-side surface S1 and the image-side surface S2 of the first lens L1 having a negative refractive power are both concave.
The second lens group G2 includes: a second lens element L2 with negative power, wherein the object-side surface S3 is convex and the image-side surface S4 is concave; the third lens element L3 with positive refractive power has a convex object-side surface S5 and a concave image-side surface S6.
The third lens group G3 includes: a fourth lens element L4 having a negative refractive power, the object-side surface S7 being convex and the image-side surface S8 being concave; a fifth lens L5 having positive refractive power, both of an object-side surface S9 and an image-side surface S10 of which are convex surfaces; a sixth lens element L6 having positive refractive power, the object-side surface S11 being concave, and the image-side surface S12 being convex; the seventh lens element L7 having negative refractive power has a convex object-side surface S13 and a concave image-side surface S14.
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 S15 and the image side surface S16 of the optical filter A1 are both planes;
the image formation surface S17 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 plane and the sagittal image plane is controlled within ± 0.08mm, 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 F-tan θ distortion of the zoom lens is controlled to within ± 2%, indicating that the wide-angle state of the zoom lens can excellently correct the F-tan θ distortion.
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 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 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 +/-0.12 mm, which shows that the zoom lens can excellently correct the field curvature in the long-focus state.
Fig. 7 shows an F-tan θ distortion curve of a zoom lens in a telephoto state in example 1, which shows F-tan θ distortions of light rays having different wavelengths at different image heights on an image forming plane, 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 +/-2%, and the zoom lens in a long focal state can excellently correct the distortion of F-tan theta.
Fig. 8 is a graph showing MTF (modulation transfer function) in the telephoto state of the zoom lens in embodiment 1, 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. 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: a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a diaphragm ST, a third lens group G3 with positive focal power and a filter A1.
The first lens group G1 includes: the first lens L1 having negative refractive power has a concave object-side surface S1 and a concave image-side surface S2.
The second lens group G2 includes: a second lens element L2 with negative power, wherein the object-side surface S3 is convex and the image-side surface S4 is concave; the third lens element L3 having positive refractive power has a convex object-side surface S5 and a concave image-side surface S6.
The third lens group G3 includes: a fourth lens element L4 with negative refractive power, wherein the object-side surface S7 is convex and the image-side surface S8 is concave; a fifth lens L5 having positive refractive power, both of the object-side surface S9 and the image-side surface S10 of which are convex surfaces; a sixth lens element L6 having a positive refractive power, the object-side surface S11 being concave and the image-side surface S12 being convex; the seventh lens element L7 having positive refractive power has a convex object-side surface S13 and a concave image-side surface S14.
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, 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 type 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 plane and the sagittal image plane is controlled within +/-0.09 mm, which shows that the field curvature can be well corrected in the wide-angle state of the zoom lens.
Fig. 11 shows F-tan θ distortion curves in the wide-angle state of the zoom lens in example 2, in which F-tan θ distortion at different image heights on the image forming surface is shown for light rays of different wavelengths, the abscissa shows F-tan θ distortion (unit:%), and the ordinate shows half field angle (unit:%). As can be seen from the figure, the F-Tan theta distortion of the zoom lens is controlled within + -3%, which shows that the wide-angle state of the zoom lens can excellently correct the F-Tan theta distortion.
Fig. 12 is a graph showing MTF (modulation transfer function) in the wide-angle state of the zoom lens in embodiment 2, which represents the lens imaging modulation degree for different spatial frequencies in each field, 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 +/-2%, which shows that the zoom lens in a long focal state can excellently correct the distortion of F-tan theta.
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. It can be seen from the figure that the MTF values of the present embodiment are both above 0.4 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.
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: a first lens group G1 with negative focal power, a second lens group G2 with positive focal power, a diaphragm ST, a third lens group G3 with negative focal power and a filter A1.
The first lens group G1 includes: the first lens L1 having negative refractive power has a concave object-side surface S1 and a concave image-side surface S2.
The second lens group G2 includes: a second lens element L2 with negative power, wherein the object-side surface S3 is convex and the image-side surface S4 is concave; the third lens element L3 having positive refractive power has a convex object-side surface S5 and a concave image-side surface S6.
The third lens group G3 includes: a fourth lens element L4 with negative refractive power, wherein the object-side surface S7 is convex and the image-side surface S8 is concave; a fifth lens L5 having positive refractive power, both of the object-side surface S9 and the image-side surface S10 of which are convex surfaces; a sixth lens element L6 having positive refractive power, the object-side surface S11 being concave, and the image-side surface S12 being convex; the seventh lens element L7 having positive refractive power has a convex object-side surface S13 and a concave image-side surface S14.
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 type 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 table 3-3.
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 an F-tan θ distortion curve in the wide-angle state of the zoom lens in example 3, 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 to within ± 4%, indicating that the wide-angle state of the zoom lens can excellently correct the F-tan θ distortion.
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 0.4 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 a meridional image plane and a sagittal image plane is controlled within +/-0.08 mm, which shows that the field curvature can be excellently corrected in a zoom lens telephoto 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 F-tan theta of the zoom lens is controlled within +/-2%, which shows that the zoom lens in a long focal state can excellently correct the distortion of 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.
Please refer to table 4, which shows the optical characteristics of the above embodiments, including the effective focal length f, the total optical length TTL, the aperture FNO, the real image height IH, and the maximum field angle FOV of the zoom lens, and the values corresponding to each conditional expression in the embodiments.
TABLE 4
In summary, the zoom lens according to the embodiment of the invention achieves the advantages of high imaging quality, miniaturization and easy processing by reasonably matching the lens shape and the focal power combination 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 examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the 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, which comprises three groups of lens groups, is characterized in that the zoom lens sequentially comprises the following components 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 optical power;
the second lens group having positive optical power includes: a second lens having a negative refractive power, a third lens having a positive refractive power;
a diaphragm;
the third lens group having positive optical power includes: the lens system comprises a fourth lens with negative focal power, a fifth lens with positive focal power, a sixth lens with positive focal power and a seventh lens with focal power.
2. The zoom lens according to claim 1, wherein both the object-side surface and the image-side surface of the first lens are concave surfaces.
3. The zoom lens according to claim 1, wherein an effective focal length f at a wide angle of the zoom lens W And effective focal length f in the telephoto state T Satisfies the following conditions: f. of T /f W ＜2.0。
4. The zoom lens of claim 1, wherein TTL is a total optical length at a wide angle of the zoom lens W And total optical length TTL in long focus state T Satisfies the following conditions: TTL (transistor-transistor logic) T /TTL W ＜1.5。
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: 3.5 < TTL/IH < 5.5.
6. The zoom lens of claim 1, wherein TTL is a total optical length at a wide angle of the zoom lens W And optical back focus BFL satisfies: BFL/TTL is more than 0.35 W 。
7. 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。
8. 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 second lens group G2 Satisfies the following conditions: 25 < | f G2 /f W |。
9. 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 third lens group G3 Satisfies the following conditions: 1.0 < f G3 /f W ＜1.5。
10. The zoom lens according to claim 1, wherein an effective focal length f of the second lens 2 And an effective focal length f of the third lens 3 Satisfies the following conditions: -1.2 < f 2 /f 3 ＜-0.8。
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| CN116755225A (en) * | 2023-08-21 | 2023-09-15 | 江西联创电子有限公司 | optical lens |
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