CN106950682B - Medium-long focal length lens - Google Patents
Medium-long focal length lens Download PDFInfo
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- CN106950682B CN106950682B CN201710296806.3A CN201710296806A CN106950682B CN 106950682 B CN106950682 B CN 106950682B CN 201710296806 A CN201710296806 A CN 201710296806A CN 106950682 B CN106950682 B CN 106950682B
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- 230000003287 optical effect Effects 0.000 claims abstract description 37
- 239000011521 glass Substances 0.000 claims description 8
- 239000002759 woven fabric Substances 0.000 claims 1
- 230000004075 alteration Effects 0.000 abstract description 10
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 6
- 210000001747 pupil Anatomy 0.000 description 4
- 201000009310 astigmatism Diseases 0.000 description 3
- 230000005499 meniscus Effects 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
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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
- G02B13/02—Telephoto objectives, i.e. systems of the type + - in which the distance from the front vertex to the image plane is less than the equivalent focal length
Abstract
The invention discloses a medium-long focal length lens, which is distributed along an object side to an image side on an optical axis in sequence: a first lens having a positive optical power; a second lens having a negative optical power; a third lens having a negative optical power; a fourth lens having positive optical power; and 1.6-Ap EFL/FL <7, wherein EFL is the effective focal length of the intermediate-length focal lens, and FL is the distance from the vertex of the lens, closest to the image plane, of the system to the image plane. The medium-long focal length lens realizes focusing by moving a single group of lenses, has less lenses, can ensure aberration, has small focusing load, easily ensures focusing speed, has small lens volume and low cost, and is beneficial to mass production.
Description
Technical Field
The invention relates to the field of optical devices, in particular to a medium and long focal length lens.
Background
At present, the known medium and long focal length lenses with the drawing angles between 20 and 30 degrees are all focused by moving a plurality of groups of lenses or a whole group of lenses, and in order to control aberration and length, a large number of lenses are introduced, so that more lenses are needed, the focusing load is large, the focusing speed is not guaranteed well, and meanwhile, the lenses are large in size and high in cost, so that a great burden is caused to consumers.
Disclosure of Invention
The invention provides a medium-long focal length lens which has the advantages of good imaging effect, high cost performance, focusing of a single group of lenses, short length and small volume.
The invention provides a medium-long focal length lens, which is characterized in that the optical axis of the lens is distributed from an object side to an image side in sequence:
a first lens having a positive optical power;
a second lens having a negative optical power;
a third lens having a negative optical power;
a fourth lens having a positive optical power;
1.6< -EFL/FL <7, wherein EFL is the effective focal length of the intermediate-long focal length lens, and FL is the distance from the vertex of the lens, closest to the image plane, of the system to the image plane.
In one embodiment, the third and fourth lenses are cemented and fixed to form a floating focusing lens group, and the stroke of the floating focusing lens group satisfies the following conditions: 0.03 and less than 0.08 in terms of L/EFL, wherein L is the total stroke of the floating focusing lens group, and EFL is the effective focal length of the intermediate telephoto lens.
In one embodiment, the optical system further comprises an optical stop, wherein the optical stop is positioned between the second lens and the third lens.
In one embodiment, the first through fourth lenses of the system have at least one cemented lens set, and at least one lens is made of 1.42-n-type yarns 1.62 and 65-lambda <95, wherein n is the refractive index of glass and lambda is the Abbe number of glass.
In one embodiment, the optical lens further comprises a fifth lens with negative optical power, wherein the object side surface of the fifth lens is convex, and the image side surface of the fifth lens is concave.
In one embodiment, the zoom lens further comprises a sixth lens with positive optical power, wherein the object side surface of the sixth lens is concave, and the image side surface of the sixth lens is convex.
In one embodiment, the optical lens further comprises a seventh lens with negative optical power, wherein the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface.
In one embodiment, the eighth lens element with positive optical power has a convex object-side surface and a convex image-side surface.
In one embodiment, the system satisfies: 0.8< -fs/EFL <2, where fs is the focal length of the positive power lens closest to the image side of the system, EFL is the system effective focal length, and the positive power lens closest to the image side is meniscus shaped.
Compared with the prior art, the invention has the following beneficial effects:
the medium-long focal length lens realizes focusing by moving the single group of lenses, has less lenses, can ensure aberration, has small focusing load, easy guarantee of focusing speed, small lens volume and low cost, and is beneficial to mass production.
Drawings
Fig. 1 is a schematic structural diagram of a middle-and-long-focus lens according to an embodiment of the present invention.
Fig. 2 is a graph of axial chromatic aberration of the intermediate telephoto lens according to the embodiment.
Fig. 3 is an astigmatism diagram of the telephoto lens according to the embodiment.
Fig. 4 is a distortion diagram of the intermediate-telephoto lens according to the embodiment.
Fig. 5 is a chromatic aberration of magnification diagram of the intermediate-telephoto lens according to the embodiment.
Detailed Description
For further explanation of the principles and construction of the present invention, reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
The utility model provides a medium telephoto lens, its distribution is along object side to image side on the optical axis in proper order:
a first lens 1 having a positive optical power;
a second lens 2 having a negative optical power;
a third lens 3 having a negative optical power;
a fourth lens 4 having positive optical power;
1.6< -EFL/FL <7, wherein EFL is the effective focal length of the intermediate-long focal length lens, and FL is the distance from the vertex of the lens, closest to the image plane, of the system to the image plane. The lens closest to the image plane is not the fourth lens here. When the ratio is less than 1.6, the optical structure is liable to become an inverse remote structure having a large viewing angle or a long back focus. When the ratio is greater than 7, the viewing angle is small, and the system is easily too long, which is not favorable for miniaturization.
The third lens 3 and the fourth lens 4 are fixedly glued to form a floating focusing lens group, and the stroke of the floating focusing lens group meets the following requirements: 0.03 and less than 0.08 in terms of L/EFL, wherein L is the total stroke of the floating focusing lens group, and EFL is the effective focal length of the intermediate telephoto lens.
The intermediate telephoto lens further comprises a diaphragm 10, and the diaphragm 10 is located between the second lens 2 and the third lens 3.
In another embodiment, the first through fourth lenses of the system have at least one cemented, fixed lens group, i.e., the first lens and/or the second lens. The second lens is fixed with the third lens and/or cemented. And at least one lens satisfies the conditions that 1.42< -n < -1.62 and 65< lambda <95, wherein n is the refractive index of glass, and lambda is the Abbe number of the glass.
In another embodiment, the telephoto lens system further includes a fifth lens 5 having a negative power, and having a convex object-side surface and a concave image-side surface. The sixth lens element 6 having positive refractive power has a concave object-side surface and a convex image-side surface. The seventh lens element 7 with negative refractive power has a concave object-side surface and a convex image-side surface. The eighth lens element 8 having positive refractive power has a convex object-side surface and a convex image-side surface.
In addition, the system of the medium-long focal length lens satisfies: 0.8< -fs/EFL <2, wherein fs is the focal length of the positive power lens closest to the image side surface of the system, and EFL is the effective focal length of the system. The positive power lens closest to the image side surface is meniscus-shaped. The lens is mainly used for eliminating the residual spherical aberration of the system.
The following further describes the intermediate telephoto lens in a specific embodiment.
The intermediate telephoto lens comprises, in order from an object side to an image side:
the first lens 1 with positive focal power has a convex object-side surface and comprises a first spherical convex surface and a second spherical convex surface.
The object side surface of the second lens 2 with negative focal power is concave, and comprises a third spherical convex surface, a fourth spherical concave surface or a plane surface.
The third lens 3 with negative focal power has a convex object-side surface and includes a fifth spherical convex surface and a sixth spherical concave surface.
The fourth lens 4 with positive focal power has a convex object-side surface, and includes a seventh spherical convex surface and an eighth spherical concave surface.
The fifth lens 5 with negative focal power has a convex object-side surface and comprises a ninth spherical convex surface and a tenth spherical concave surface.
The object side surface of the sixth lens 6 with positive focal power is a concave surface and comprises an eleventh spherical convex surface and a twelfth spherical convex surface.
The seventh lens 7 with negative focal power has a concave object-side surface and includes a thirteenth spherical concave surface and a fourteenth spherical convex surface.
The eighth lens 8 with positive optical power has a convex object-side surface, and includes a fifteenth convex spherical surface and a sixteenth convex spherical surface.
Wherein, the second spherical surface of the first lens 1 is cemented with the third spherical surface of the second lens 2, and the sixth spherical surface of the third lens 3 is cemented with the seventh spherical surface of the fourth lens 4.
A lens group formed by gluing the third lens 3 and the fourth lens 4 is used as a floating focusing lens group, and when the lens group moves towards the image side, the focusing is realized by remote distance. A diaphragm 10 is located between the second lens 2 and the third lens 3.
The system satisfies 1.6< EFL/FL <7, wherein EFL is the effective focal length of the system, and FL is the optical back focus of the system, namely the distance from the vertex of the lens closest to the image plane. In this embodiment, the lens closest to the image plane is the eighth lens. The first lens, the second lens, the third lens and the fourth lens of the system have at least one group of cemented lenses, and at least one lens satisfies the following conditions: n is more than 1.42 and less than 1.62, and lambda is more than 65 and less than 95, wherein n is the refractive index of the glass, and lambda is the Abbe number of the glass.
The system meets the following requirements: fs/EFL is more than 0.8 and less than 2, wherein fs is the focal length of the last meniscus positive focal power lens of the system, and EFL is the effective focal length of the system.
Hereinafter, the medium telephoto lens is described in detail with a specific embodiment. System parameters: TTL =56.2; EFL =50.2; h =21.6; f/# =2.4; the thickness column has a value of "/" before the interval at infinity, and "/" after the interval at the latest focus.
| Surface type | Radius of curvature | Thickness of | Material | Effective half caliber |
| Article surface | All-round | Infinite/600 | All-round | |
| The first spherical surface | 28 | 4.47 | 1.50/81.59 | 11 |
| Second spherical surface | -42.78 | 0.8 | 1.62/60.37 | 11 |
| Third sphere | All-round | 2.096 | 11 | |
| Diaphragm | All-round | 3.47/1 | 9.4 | |
| Fifth spherical surface | 16.83 | 8 | 1.85/23.79 | 9.6 |
| Sixth spherical surface | 8.765 | 4 | 1.50/81.59 | 6.6 |
| Diaphragm | 67.49 | 1.14/3.61 | 6.2 | |
| The seventh spherical surface | 37.48 | 0.95 | 1.60/38.01 | 9.6 |
| The eighth (ninth) spherical surface | 12.79 | 3.39 | 6.6 | |
| Tenth spherical surface | -16.5 | 3.6 | 1.72/29.51 | 6.6 |
| Eleventh spherical surface | -14.6 | 2.67 | 9.6 | |
| Twelfth sphere surface | -11.97 | 1.15 | 1.50/81.59 | 7.96 |
| Thirteenth sphere | -73.2 | 0.1 | 9.6 | |
| Fourteenth sphere | 35.74 | 4 | 1.71/53.87 | 10.5 |
| Fifteenth spherical surface | -35.74 | 15.15 | 10.5 | |
| Image plane | Go to nothing | 11 |
Fig. 2 is an on-axis chromatic aberration diagram of the intermediate-telephoto lens according to the embodiment of the present invention, where the on-axis chromatic aberration diagram shows the degree of deviation of different bands from ideal image plane positions in different pupil bands. The horizontal axis represents offset and the vertical axis represents normalized pupil band. Looking primarily at the smallest offset for all wavelengths near the 0.707 pupil band, the transverse axis distance for the wavelengths 486.1nm and 546.1nm, which are farthest apart in the 0.707 pupil band, is about 0.05mm, as in this figure.
Fig. 3 is an astigmatism graph of a medium-telephoto lens according to an embodiment of the invention. Astigmatism represents the degree of deviation of the image field from the ideal image field in the design meridional and sagittal directions. The horizontal axis represents the offset amount, and the vertical axis represents the half image height. If the image field deviation of the image system is within 0.1 in the whole field of view, the maximum deviation of the meridional and sagittal curves is about 0.05.
Fig. 4 is a distortion plot of a wide-angle lens according to an embodiment of the present invention. The distortion map represents the difference between the actual image height and the ideal image height. The horizontal axis represents the distortion percentage and the vertical axis represents the half-image height. It can be seen that the distortion of the system is within 0.5%, and the human eye generally cannot distinguish the distortion of the photographed object.
Fig. 5 is a graph of chromatic aberration of magnification of the wide-angle lens according to the embodiment of the present invention. From this figure the total field of view of the system is at most around 14 microns.
The medium and long focal length lens of the invention realizes focusing by moving a single group of lenses, has less lenses, can ensure aberration, has small focusing load, easy guarantee of focusing speed, small lens volume and low cost, and is beneficial to mass production.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all equivalent structural changes made by using the contents of the present specification and the drawings are included in the present invention.
Claims (4)
1. The medium-long focal length lens is characterized in that the optical axis is distributed along the object side to the image side in sequence:
the first lens with positive focal power has a convex object-side surface and a convex image-side surface;
a second lens having a negative optical power;
a third lens having a negative optical power;
a fourth lens having a positive optical power;
the optical lens also comprises a fifth lens with negative focal power, wherein the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a concave surface;
the lens also comprises a sixth lens with positive focal power, wherein the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface;
the optical lens also comprises a seventh lens with negative focal power, wherein the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface;
an eighth lens element with positive refractive power having a convex object-side surface and a convex image-side surface;
1.6-woven fabric EFL/FL <7, wherein FL is the distance from the top point of a lens, closest to an image surface, of a system to the image surface;
the third lens and the fourth lens are fixedly glued to form a floating focusing lens group, and the stroke of the floating focusing lens group meets the following requirements: 0.03 and less than 0.08 in terms of L/EFL, wherein L is the total stroke of the floating focusing lens group, and EFL is the effective focal length of the intermediate telephoto lens system;
the total number of lenses having optical power was 8.
2. The intermediate telephoto lens according to claim 1, further comprising an optical stop, the optical stop being located between the second lens and the third lens.
3. The intermediate telephoto lens as claimed in claim 1, wherein the first lens and the second lens are cemented; the third lens and the fourth lens are glued; and at least one lens satisfies the conditions that 1.42 and n are woven into 1.62 and 65< lambda <95, wherein n is the refractive index of glass and lambda is the Abbe number of the glass.
4. The intermediate telephoto lens as claimed in claim 1, wherein the system satisfies: 0.8 & lt fs/EFL <2, wherein fs is the focal length of the positive power lens closest to the image side of the system, EFL is the effective focal length of the system, and the positive power lens closest to the image side is meniscus-shaped.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201710296806.3A CN106950682B (en) | 2017-04-28 | 2017-04-28 | Medium-long focal length lens |
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| CN201710296806.3A CN106950682B (en) | 2017-04-28 | 2017-04-28 | Medium-long focal length lens |
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| CN106950682B true CN106950682B (en) | 2023-02-10 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113985584B (en) * | 2017-11-22 | 2024-03-29 | 浙江舜宇光学有限公司 | Optical imaging lens |
| WO2021128394A1 (en) * | 2019-12-28 | 2021-07-01 | 诚瑞光学(常州)股份有限公司 | Camera optical lens |
| CN112505879B (en) * | 2020-11-18 | 2023-11-24 | 西安玄瑞光电科技有限公司 | Wide-view-field long-focus high-resolution lens |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP3715735B2 (en) * | 1997-01-24 | 2005-11-16 | マミヤ・オーピー株式会社 | telescope lens |
| JP2002196241A (en) * | 2000-12-27 | 2002-07-12 | Asahi Optical Co Ltd | Zoom lens system |
| JP6015333B2 (en) * | 2012-10-16 | 2016-10-26 | リコーイメージング株式会社 | Large aperture telephoto lens system |
| JP2015004717A (en) * | 2013-06-19 | 2015-01-08 | リコーイメージング株式会社 | Single focus lens system |
| CN203981958U (en) * | 2014-06-26 | 2014-12-03 | 北京蓝思泰克科技有限公司 | A kind of large zoom ratio medium wave infrared continuous zoom lens |
| CN206920691U (en) * | 2017-04-28 | 2018-01-23 | 深圳市东正光学技术有限公司 | Middle telephoto lens |
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Address after: 518172 the whole floor of 6 / F, building 1, xinwujing Industrial Park, No. 32, cuibao Road, Baolong street, Longgang District, Shenzhen, Guangdong Province Applicant after: Shenzhen Dongzheng Optical Technology Co.,Ltd. Address before: 518116 east area, 10th floor, tianhengda Industrial Park, No. 2, Chengxin Road, Baolong Industrial Zone, Longgang street, Longgang District, Shenzhen, Guangdong Province Applicant before: SHENZHEN DZO OPTICS TECHNOLOGY Co.,Ltd. |
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