CN109856787B - zoom lens - Google Patents
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- CN109856787B CN109856787B CN201811623338.7A CN201811623338A CN109856787B CN 109856787 B CN109856787 B CN 109856787B CN 201811623338 A CN201811623338 A CN 201811623338A CN 109856787 B CN109856787 B CN 109856787B
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- 230000003287 optical effect Effects 0.000 claims abstract description 10
- 230000004075 alteration Effects 0.000 description 19
- 230000000694 effects Effects 0.000 description 7
- 239000011521 glass Substances 0.000 description 4
- 230000007547 defect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 206010010071 Coma Diseases 0.000 description 1
- 201000009310 astigmatism Diseases 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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Abstract
The invention belongs to the technical field of optical devices, and particularly relates to a zoom lens, which sequentially comprises a first lens group G1 with positive diopter, a second lens group G2 with negative diopter, a third lens group G3 with positive diopter and a fourth lens group G4 with positive diopter from an object side to an image plane side; when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved from the object side to the image side, the third lens group G3 is moved from the object side to the image side, the halfway return is moved from the image side to the object side, and the fourth lens group G4 is moved from the image side to the object side; the first lens group G1 comprises a negative diopter front group G1a formed by three negative lenses, a middle group G1b formed by two positive lenses and a positive diopter rear group G1c, and when an object moves from infinity to close distance, the middle group G1b moves from the object side to the image plane side to realize focusing; the zoom lens provided by the invention has the advantages of small volume, high performance and low cost, and the zoom magnification exceeds 3 times.
Description
Technical Field
The invention belongs to the technical field of optical devices, and particularly relates to a zoom lens.
Background
Currently, most of known zoom film lenses have a structure in which a first group of fixed lenses with positive diopters is combined with a plurality of moving groups, such as disclosed in japanese patent application laid-open No. 2015-4917: the first group is fixed in positive diopter from one side of the object, the second group is respectively moved to the 2 nd group of negative diopter, the 3 rd lens group of negative diopter, the 4 th group of positive diopter, the 5 th group of fixed positive diopter and other groups, and when the object moves from infinity to close distance, the combination Jiao Zu is a part of the middle of the first group, and the lens moves to the image plane direction for focusing.
There are also Japanese patent laid-open No. 2015-18083: the first group is fixed in positive diopter from one side of the object, the second group is respectively moved to the 2 nd group of negative diopter, the 3 rd lens group of negative diopter, the 4 th group of negative diopter, the 5 th group of fixed positive diopter and other groups, and when the object moves from infinity to close distance, the combination Jiao Zu is a part of the middle of the first group, and the image surface direction is moved to focus.
Although the structure realizes high performance including more than 3 times of zooming function, the structure is complicated due to excessive moving groups, and the defects of huge volume, high manufacturing difficulty, high cost and the like are caused by adopting aspheric correction.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a zoom lens which has the advantages of simple structure, small volume and low manufacturing cost.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
a zoom lens including, in order from an object side to an image plane side, a first lens group G1 of positive diopter, a second lens group G2 of negative diopter, a third lens group G3 of positive diopter, and a fourth lens group G4 of positive diopter;
wherein, when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved from the object side to the image side, the third lens group G3 is moved from the object side to the image side, the halfway folding is moved from the image side to the object side, and the fourth lens group G4 is moved from the image side to the object side;
the first lens group G1 comprises a negative diopter front group G1a formed by three negative lenses, a middle group G1b formed by two positive lenses and a positive diopter rear group G1c, and when an object moves from infinity to close distance, the middle group G1b is moved from the object side to the image plane side to realize focusing;
the zoom lens also satisfies the following conditional expression:
3≤WL/F1b≤7 (1)
2.5≤|F1c/F1b|≤6.5 (2)
0.1≤|Tbc/Fw|≤0.4 (3)
wherein,,
WL: the optical full length of the zoom lens; the total optical length is the distance from the first surface to the image surface;
f1b: a focal length of the intermediate group G1b of the first lens group G1;
f1c: a focal length of a rear group G1c of the first lens group G1;
tbc: in the infinity state, the air spaces of the intermediate group G1b and the rear group G1c in the first lens group G1;
fw: in the infinity state, the optical system at the wide-angle end has a focal length.
Preferably, the first lens group G1 satisfies the following conditional expression:
0.5≤|F1a/F1|≤0.8 (4)
wherein,,
f1a: a focal length of the front group G1a in the first lens group G1;
f1: in the infinity state, the focal length of the first lens group G1.
Preferably, the third lens group G3 is folded halfway when moving from the wide-angle end to the telephoto end, forms a U-shaped movement locus, and satisfies the following conditional expression:
0.5≤(S2+S3+S4)/(Fw×Z)≤0.8 (5)
wherein,,
s2: a total movement amount of the second lens group G2 upon zooming from the wide-angle end to the telephoto end;
s3: a total movement amount of the third lens group G3 upon zooming from the wide-angle end to the telephoto end;
s4: a total movement amount of the fourth lens group G4 upon zooming from the wide-angle end to the telephoto end;
fw: in an infinity state, an optical system focal length at a wide-angle end;
z: zoom magnification.
In the present invention, if the upper limit of the conditional expression (1) is exceeded, the total lens length is too long, or the diopter of the intermediate group G1b is too strong, which may result in a huge volume, or the performance is low because the diopter of the focal group is too strong; if the lower limit of the conditional expression (1) is exceeded, although miniaturization can be achieved, the focal group diopter is too weak, the focal length of movement is large, and the near-shooting ability is difficult to achieve.
In the present invention, if the upper limit of the conditional expression (2) is exceeded, the diopter of the intermediate group G1b of the first lens group G1 is strong, and although the near-field power is improved, too strong causes spherical aberration, distortion and other various aberrations which cannot be corrected well, and if the lower limit of the conditional expression (2) is exceeded, the performance is easily corrected, but the diopter of the intermediate group G1b is too weak, and the amount of focal shift is increased, and the volume is also increased, and if the volume is controlled, the near-field power is reduced, so that a good balance between the volume and the performance cannot be achieved.
In the present invention, if the upper limit of the conditional expression (3) is exceeded, the interval between the intermediate group G1b and the rear group G1c in the first lens group G1 is too large, and although the near-field photographing capability is easy to realize, the lens volume is large, and especially the front group large-caliber lens weight is drastically increased, and the volume, the cost and the processing difficulty are all increased, so that the small-sized and low-cost zoom lens cannot be realized. If the lower limit of the conditional expression (3) is exceeded, the interval between the intermediate group G1b and the rear group G1c is too small, and although miniaturization is easy to achieve, the total Jiao Jiange is small, and it is difficult to achieve good near-field shooting ability.
In the present invention, if the upper limit of the conditional expression (4) is exceeded, the negative refractive power of the front group G1a in the first lens group G1 is too weak, and since both the intermediate group G1b and the rear group G1c are positive refractive powers, it is difficult to achieve the function of correcting the positive and negative aberrations with each other, and also the wide-angle effect cannot be achieved because the negative refractive power is too weak. If the lower limit of the conditional expression (4) is exceeded, although a good positive and negative aberration correction effect can be achieved, excessive aberrations such as edge coma and astigmatism are generated because the negative diopter is too strong, and the correction of the aberrations is difficult.
In the present invention, if the upper limit of the conditional expression (5) is exceeded, the movement amounts of the second lens group G2, the third lens group G3, and the fourth lens group G4 are excessively large, and although the high magnification effect can be satisfactorily achieved, the optical system is bulky, and the cost increases. If the lower limit of the conditional expression (5) is exceeded, although a small volume can be achieved, if the same zoom magnification is to be achieved, the diopter of each lens group is increased, which causes various aberrations to occur, and it is difficult to achieve a high performance requirement.
Compared with the prior art, the invention has the following technical effects:
the invention can realize the effects of small volume, high performance and low cost by reasonable lens group matching and appointed moving modes, and realize the zoom lens with the zoom multiplying power exceeding 3 times.
Drawings
Fig. 1 is a schematic view of a zoom lens provided in embodiment 1;
fig. 2 shows infinity, spherical aberration, field curvature aberration, distortion aberration and chromatic aberration of magnification for the closest distance taken in example 1;
fig. 3 is a schematic view of a zoom lens provided in embodiment 2;
fig. 4 shows infinity, spherical aberration, field curvature aberration, distortion aberration and chromatic aberration of magnification for the closest distance taken in example 2.
Detailed Description
The invention is further described in the following with reference to specific embodiments in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the invention easy to understand.
Example 1
As shown in fig. 1, the lens system includes four parts, in order from an object side to an image plane side, a first lens group G1 of positive refractive power, a second lens group G2 of negative refractive power, a third lens group G3 of positive refractive power, and a fourth lens group G4 of positive refractive power;
when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved from the object side to the image plane side by an amount S2, the third lens group G3 is first moved from the object side to the image plane side, halfway folding is moved from the image plane side to the object side, the total amount of movement is S3, and the fourth lens group G4 is moved from the image plane side to the object side; the first lens group G1 is composed of three parts, namely a negative diopter front group G1a composed of three negative lenses, a middle group G1b composed of two positive lenses and a positive diopter rear group G1 c; when the object moves from infinity to a close distance, the intermediate group G1b is brought into focus by the object side to the image plane side.
The spherical aberration, curvature of field, distortion, and chromatic aberration of magnification at infinity in example 1 are shown in fig. 2.
The data for example 1 are as follows:
wherein,,
r (mm): radius of curvature of each face;
d (mm): each lens spacing and lens thickness;
nd: refractive index of each glass of d-line;
vd: abbe number of the glass;
focal distance: 20.8060-36.2317-77.8754;
Fno：2.8～2.8～2.8；
half angle ω: 34.65-20.5-9.85;
| focal distance | 20.806 | 36.2317 | 77.8754 |
| D(6) | 0.8054 | 0.8054 | 0.8054 |
| D(10) | 5.4231 | 5.4231 | 5.4231 |
| D(15) | 0.9665 | 18.1879 | 29.5193 |
| D(23) | 33.9078 | 22.2733 | 1.4163 |
| D(28) | 21.6004 | 12.1571 | 10.0212 |
| D(36) | 28.2757 | 32.1271 | 43.7612 |
Example 2
As shown in fig. 3, four portions including a first lens group G1 of positive diopter, a second lens group G2 of negative diopter, a third lens group G3 of positive diopter, and a fourth lens group G4 of positive diopter in this order from the object side to the image plane side;
when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved from the object side to the image plane side by an amount S2, the third lens group G3 is first moved from the object side to the image plane side, halfway folding is moved from the image plane side to the object side, the total amount of movement is S3, and the fourth lens group G4 is moved from the image plane side to the object side; the first lens group G1 is composed of three parts, namely a negative diopter front group G1a composed of three negative lenses, a middle group G1b composed of two positive lenses and a positive diopter rear group G1 c; when the object moves from infinity to a close distance, the intermediate group G1b is brought into focus by the object side to the image plane side.
The spherical aberration, curvature of field, distortion, and chromatic aberration of magnification at infinity in example 2 at the closest shooting distance are shown in fig. 4.
The data for example 2 are as follows:
wherein,,
r (mm): radius of curvature of each face;
d (mm): each lens spacing and lens thickness;
nd: refractive index of each glass of d-line;
vd: abbe number of the glass;
focal distance: 23.0191-40.1343-86.2597;
Fno：2.8～2.8～2.8；
half angle ω:32.2 to 18.9 to 9.05;
| focal distance | 23.0191 | 40.1343 | 86.2597 |
| D(6) | 1.7834 | 1.7834 | 1.7834 |
| D(10) | 4.7568 | 4.7568 | 4.7568 |
| D(15) | 1.1774 | 18.6681 | 29.7437 |
| D(23) | 38.977 | 25.4396 | 1.6766 |
| D(29) | 18.0305 | 9.3741 | 7.7281 |
| D(37) | 31.326 | 36.0291 | 50.3625 |
The condition is satisfied:
| example 1 | Example 2 | |
| The condition (1) is that WL/F1b is not less than 3 and not more than 7 | 5.802 | 5.752 |
| The condition (2) is that the ratio of F1c to F1b is less than or equal to 2.5 and less than or equal to 6.5 | 5.156 | 3.706 |
| Conditional (3) 0.1-0.4 of Tbc/Fw | 0.261 | 0.207 |
| Conditional (4) that the content of F1a/F1 is less than or equal to 0.5 and less than or equal to 0.8 | 0.656 | 0.615 |
| The condition (5) is that (S2+S3+S4)/(Fw×Z) is less than or equal to 0.5 and less than or equal to 0.8 | 0.616 | 0.652 |
By the technical scheme provided by the invention, the lens comprises four parts, namely a first lens group G1 with positive diopter, a second lens group G2 with negative diopter, a third lens group G3 with positive diopter and a fourth lens group G4 with positive diopter from the object side to the image plane side in the embodiment 1 and the embodiment 2;
when zooming from the wide-angle end to the telephoto end, the first lens group G1 is fixed, the second lens group G2 is moved from the object side to the image plane side by an amount S2, the third lens group G3 is first moved from the object side to the image plane side, halfway folding is moved from the image plane side to the object side, the total amount of movement is S3, and the fourth lens group G4 is moved from the image plane side to the object side; the first lens group G1 is composed of three parts, namely a negative diopter front group G1a composed of three negative lenses, a middle group G1b composed of two positive lenses and a positive diopter rear group G1 c; when the object moves from infinity to a close distance, the intermediate group G1b is brought into focus by the object side to the image plane side. Because the focal length of each lens group is optimally matched with the appointed moving track of each lens group, the lens group is reduced in quantity, the structure is simplified, the size is small, the expensive aspheric surface is eliminated, the processing difficulty is reduced, the effects of low cost, high performance and the zooming multiplying power exceeding 3 times are realized. The lens can be widely applied to the fields of digital camera lenses and video camera lenses, in particular to film lenses and the like.
The foregoing has outlined and described the basic principles, main features and features of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made therein without departing from the spirit and scope of the invention, which is defined by the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (3)
1. A zoom lens, characterized in that: a first lens group (G1) of positive diopter, a second lens group (G2) of negative diopter, a third lens group (G3) of positive diopter and a fourth lens group (G4) of positive diopter are included in this order from the object side to the image plane side;
wherein, when zooming from the wide-angle end to the telephoto end, the first lens group (G1) is fixed, the second lens group (G2) moves from the object side to the image side, the third lens group (G3) moves from the object side to the image side, the halfway foldback moves from the image side to the object side, and the fourth lens group (G4) moves from the image side to the object side;
the first lens group (G1) comprises a negative diopter front group (G1 a) formed by three negative lenses, a middle group (G1 b) formed by two positive lenses and a positive diopter rear group (G1 c), and when an object moves from infinity to close distance, the middle group (G1 b) is formed by moving from the object side to the image plane side to realize focusing;
the zoom lens also satisfies the following conditional expression:
3 ≤ WL/F1b ≤ 7 （1）
2.5 ≤ ｜F1c/F1b｜ ≤ 6.5 （2）
0.1 ≤ ｜Tbc/Fw｜ ≤ 0.4 （3）
wherein,,
WL: the optical full length of the zoom lens;
f1b: a focal length of an intermediate group (G1 b) of the first lens group (G1);
f1c: a focal length of a rear group (G1 c) of the first lens group (G1);
tbc: in an infinity state, air gaps of the intermediate group (G1 b) and the rear group (G1 c) in the first lens group (G1);
fw: in the infinity state, the optical system at the wide-angle end has a focal length.
2. The zoom lens according to claim 1, wherein the first lens group (G1) satisfies the following conditional expression:
0.5 ≤ ｜F1a/F1｜ ≤ 0.8 （4）
wherein,,
f1a: a focal length of a front group (G1 a) in the first lens group (G1);
f1: in an infinity state, the focal length of the first lens group (G1) is set.
3. The zoom lens according to claim 1 or 2, wherein the third lens group (G3) is folded halfway and forms a U-shaped movement locus when moving from the wide-angle end to the telephoto end, and satisfies the following conditional expression:
0.5 ≤（S2+S3+S4）/(Fw×Z) ≤ 0.8 （5）
wherein,,
s2: a total movement amount of the second lens group (G2) when zooming from the wide-angle end to the telephoto end;
s3: a total movement amount of the third lens group (G3) upon zooming from the wide-angle end to the telephoto end;
s4: a total movement amount of the fourth lens group (G4) when zooming from the wide-angle end to the telephoto end;
fw: in an infinity state, an optical system focal length at a wide-angle end;
z: zoom magnification.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811623338.7A CN109856787B (en) | 2018-12-28 | 2018-12-28 | zoom lens |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811623338.7A CN109856787B (en) | 2018-12-28 | 2018-12-28 | zoom lens |
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| CN109856787A CN109856787A (en) | 2019-06-07 |
| CN109856787B true CN109856787B (en) | 2023-10-20 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP7516132B2 (en) | 2020-06-29 | 2024-07-16 | キヤノン株式会社 | Zoom lens and imaging device |
| JP7536526B2 (en) | 2020-06-29 | 2024-08-20 | キヤノン株式会社 | Zoom lens and imaging device |
| CN111650734B (en) * | 2020-08-10 | 2020-12-29 | 嘉兴中润光学科技有限公司 | Large wide-angle camera device and zoom lens |
| CN113721352B (en) * | 2021-09-01 | 2024-10-22 | 安徽长庚光学科技有限公司 | Micro-distance deformed wide screen lens and digital camera and video camera with same |
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| CN102955231A (en) * | 2011-08-22 | 2013-03-06 | 株式会社腾龙 | Large-aperture zoom lens |
| JP2015004917A (en) * | 2013-06-24 | 2015-01-08 | キヤノン株式会社 | Zoom lens and image capturing device having the same |
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| JP2017181720A (en) * | 2016-03-30 | 2017-10-05 | キヤノン株式会社 | Zoom lens and imaging apparatus having the same |
| CN209248146U (en) * | 2018-12-28 | 2019-08-13 | 安徽长庚光学科技有限公司 | Zoom lens |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6693750B2 (en) * | 2001-09-19 | 2004-02-17 | Nikon Corporation | Zoom lens system |
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- 2018-12-28 CN CN201811623338.7A patent/CN109856787B/en active Active
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|---|---|---|---|---|
| CN102308243A (en) * | 2009-02-05 | 2012-01-04 | 株式会社腾龙 | Macro Lens |
| CN102955231A (en) * | 2011-08-22 | 2013-03-06 | 株式会社腾龙 | Large-aperture zoom lens |
| JP2015004917A (en) * | 2013-06-24 | 2015-01-08 | キヤノン株式会社 | Zoom lens and image capturing device having the same |
| EP2824496A1 (en) * | 2013-07-10 | 2015-01-14 | Canon Kabushiki Kaisha | Zoom lens and image pickup apparatus inculding the same |
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