GB2131198A - Wide angle lens having four lenses - Google Patents
Wide angle lens having four lenses Download PDFInfo
- Publication number
- GB2131198A GB2131198A GB08326660A GB8326660A GB2131198A GB 2131198 A GB2131198 A GB 2131198A GB 08326660 A GB08326660 A GB 08326660A GB 8326660 A GB8326660 A GB 8326660A GB 2131198 A GB2131198 A GB 2131198A
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- GB
- United Kingdom
- Prior art keywords
- lens
- lens group
- fno
- astigmatism
- spherical aberration
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000004075 alteration Effects 0.000 claims abstract description 50
- 230000005499 meniscus Effects 0.000 claims abstract description 3
- 201000009310 astigmatism Diseases 0.000 claims description 16
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 2
- 230000003287 optical effect Effects 0.000 abstract description 2
- 238000010276 construction Methods 0.000 abstract 1
- 206010010071 Coma Diseases 0.000 description 8
- 230000006866 deterioration Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/04—Reversed telephoto objectives
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/34—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having four components only
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
This wide angle lens is used for an optical system whose image plane size is small such as a disk camera or facsimile. This lens system comprises a first biconvex lens in which an intense convex surface is directed towards an object, a second biconcave lens in which an intense concave surface is directed towards an image, a third biconvex lens, and a fourth negative meniscus lens in which a convex surface is directed towards the image and satisfies four specified conditions. This lens system is simple in construction, comprises four groups and four lenses, can provide adequate correction of aberration without use of aspherical surface, and is of a small type in which the telephoto index is less than 1.2. <IMAGE>
Description
SPECIFICATION
Wide angle lens
The present invention relates to a wide angle lens having an angle of view of approximately 57 degrees and a brightness of approximately F2.8, and particularly, to a wide angle lens used for an optical system whose image plane size is relatively small such as a disk camera, facsimile or the like.
In the past, a lens system of this kind has not taken into consideration the compactness of a lens because the focal length thereof is small, and the lens system had a great telephoto index. A lens for a disk camera recently developed has been designed so that the telephoto index was made to be small by employment of an aspherical surface.
However, the use of an aspherical surface increases the cost of the lens.
The present invention is intended to provide a wide angle lens which comprises four groups and four lenses, which can adequately make aberration correction of small telephoto index with only a spherical surface without use of an aspherical surface and which is suitable for the above-described uses.
The invention provides a wide angle lens comprising a first lens group composed of a biconvex lens in which an intense convex surface is directed towards an object, a second lens group composed of a biconcave lens in which an intense concave surface is directed towards an image, a third lens group which is a biconvex lens, and a fourth lens group which is a negative meniscus in which a convex surface is directed towards an image, arranged in order from the object side, said wide angle lens being satisfied with the following conditions: -o.o5/f < 1/f1.2 < 0.15/f . . . (1) 1.27/f < 1/f1.2.3 < 1.55/f . . . (2) 0.22f < D6 < 0.36f . . . (3)
N1, N2, N4 > 1.75, N3 > 1.68 .. (4) where
f : focal length of the whole system fls : synthesized focal length of the first and second lens groups fas 2.3: synthesized focal length of the first to third lens groups
D6 : spacing between the third lens group and the fourth lens group
R7 : radius of curvature of the fourth lens group on the object side N1 : refractive index of niter of the ith lens group.
The telephoto index could be made to hold its value less than approximately 1.2.
In the lens of the present invention, a diaphragm is disposed between the second lens group and the third lens group in order to improve the condition of out-of-axis light flux. To this end, a negative distortion aberration occurring in the third lens group is corrected by use of a biconcex lens in the first lens group.
The aforesaid conditions (1) and (2) are the conditions necessary to proper spherical aberration, coma aberration and distortion aberration.
If the value becomes below the lower limit of the condition (1), the focal length of the first lens group becomes long or the focal length of the second lens group becomes short, and therefore, the over coma flare and the great under distortion aberration occur. Further, since the position of the principal point is moved toward the image, the telephot index becomes great. Conversely, if the value exceeds the upper limit, the focal length of the first lens group becomes short or the focal length of the second lens group becomes long, and therefore, the great under spherical aberration occurs.
If the value becomes below the lower limit of the condition (2), the over coma flare occurs and the telephoto index further becomes great. Conversely, if the value exceeds the upper limit, the under coma flare, the great under distortion aberration and the under spherical aberration occur.
The condition (3) is the condition necessary to maintain the telephoto index to be small while holing various aberrations within a suitable range.
If the value becomes below the lower limit of the condition (3), it is necessary that to maintain the telephoto index to be small, 1/f1.2 be made to be greater than the upper limit of the condition (1) or 1/f1.2.3 be made to be greater than the upper limit of the condition (2). Conversely, if the value exceeds the upper limit of the condition (3), the telephoto index becomes small but the fourth lens group is greatly moved away from the third lens group, and therefore, correction of the spherical aberration and coma aberration is difficult to make.
The condition (4) is the condition necessary to maintain the Petzval's sum of the whole system within a proper range and to maintain the spherical aberration and coma aberration in a proper range and is the condition necessary to maintain the telephoto index to be small. If the refractive indexes N1 and N3 of the convex lens group become smaller than the lower limit, the radius of curvature of the convex lens group becomes small, and therefore, the Petzval's sum becomes great and the curve of an image surface becomes large. Furthermore, the spherical abberation is short in correction.
Conversely, if the refractive indexes N2 and N4 of the concave lens group become smaller than the lower limit of the condition (4), the radius of curvature of the concave lens group becomes small, and therefore, the
Petzval's sum becomes small, and the image surface is bended towards the image, as a consequence of which astigmatic difference becomes large and the over coma flare occurs.
Even if the refractive index of each lens group becomes smaller than the lower limit of the condition (4), each of the aberrations can be well corrected. However, the present invention is concerned with the lens system whose focal length is small, and therefore, the readiness of working each of the lens groups has to be taken into consideration. If the refractive index of the convex lens group becomes smaller than the lower limit of the condition (4), the aforementioned deterioration of aberrations brings forth. The refractive index of the concave lens group becomes small, the radius of curvature of the convex lens group becomes small, and therefore, working of lens becomes difficult unless the thickness of the convex lens above the axis is increased.However, if the thickness of the convex lens group above the axis is increased, the telephoto index of the lens system cannot be maintained to be small.
Brief description of the drawings
Figure lisa sectional view of a lens in a first embodiment of the present invention;
Figures 2, 3, 4, 5, 6, 7, 8 and 9 are aberration curves of embodiment 1, embodiment 2, embodiment 3, embodiment 4, embodiment 5, embodiment 6, embodiment 7 and embodiment 8, respectively.
Detailed description of the preferred embodiments
In the following, embodiments of the lens system in accordance with the present invention will be described.
In addition to the above-described conditions, in the lens system of the present invention, R7 is desirably satisfied with the following condition in order to hold the spherical aberration and coma aberration within the proper range. All the embodiments are satisfied with even this condition.
-0.4f < R7 < -0.32f . . . (5)
In the embodiments, a reference character R designates the radius of curvature, D the spacing between surfaces, N the refractive index, Vthe Abbe number, and Tthe telephone index.
Embodiment 1
f = 10 FNo = 2.87 2w = 57 30' Surface No. R D N V
1 4.8462 1.3550 1.834 37.2
2 -37.7386 0.116
3 -10.9661 0.3985 1.80518 25.4
4 5.3667 1.7934
5 8.4179 1.8970 1.7225 49.6
6 -8.4179 2.5905
7 -3.6498 0.5580 1.834 37.2
8 -8.3693
T=1.197 1/f1,2=0.0538/f 1/f1.2.3 1.4861/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 2.
Embodiment2
f = 10 FNO = 2.87 2w = 57 24' Surface No. R D N V
1 4.7557 1.440 1.8044 39.6
2 -41.0084 0.120
3 -10.71 0.480 1.7847 26.2
4 5.2819 1.600
5 8.304 2.000 1.7725 49.6
6 -8.304 2.560
7 -3.6302 0.560 1.834 37.2
8 -8.0407
T=1.198 1/f1.2=0.041 5/f 1/f1.2.3= 1.452/f
The spherical aberration, astigmatism and distortion abberation curves are shown in Figure 3.
Embodiment 3
f = 10 FNo = 2.87 2w = 57931' Surface No. R D N V
1 4.7667 1.36 1.834 37.2
2 -34.8295 0.112
3 -11.1529 0.40 1.80518 25.4
4 5.2834 1.80
5 8.48 2.08 1.7725 49.6
6 -8.48 2.44
7 -3.7396 0,56 1.834 37.2
8 -8.9658
T=1.199 1/f12=0.0982/f 1/f1.2.3 1.4688/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 4.
Embodiment 4
f = 10 FNo = 2.87 2w =57026' Surface No. R D N V
1 4.7929 1.440 1.834 37.2
2 -37.1508 0.112
3 -10.7251 0.480 1.80518 25.4
4 5.0617 1.600
5 8.8201 1.840 1.7725 49.6
6 -7.9615 2.720
7 -3.7125 0.56 1.834 37.2
8 -7.9804
T=1.195 1/f1.2=0.0181/f 1/f1.2.3=1 .4300/f
The spherical aberratin, astigmatism and distortion aberration curves are shown in Figure 5.
Embodiment5
f = 10 FNO = 2.87 2w = 57 32' Surface No. R D N V
1 4.7655 1.440 1.8044 39.6
2 -51.0659 0.120
3 - 11.0890 0.480 1.7847 26.2
4 5.3157 1.60
5 8.0697 2.00 1.7725 49.6
6 -8.5244 2.56
7 -3.5572 0.56 1.8044 39.6
8 -7.9360
T=1.199 1/f1.2=0.031 2/f 1/f1.2.3= 1.4500/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 6.
Embodiment 6
f = 10 FNo = 2.87 2w = 56 26' Surface No. R D N V
1 5.0040 1.360 1.834 37.2
2 -26,5336 0.112
3 -10.2108 0.400 1.80518 25.4
4 5.5457 1.800
5 . 8.9361 1.760 1.7725 49.6
6 -8.8725 3.067
7 -3.6489 0.560 1.834 37.2
8 -8.3905
T=1.188 1/f1.2=0.09681/f 1/f123=1.4143/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 7.
Embodiment 7
f = 10 FNo = 2.87 2w = 56 12'
Surface No. R D N V
1 > 4.7376 1.360 1.834 37.2
2 -31.2778 0.112
3 -10.4125 0.400 1.80518 25.4
4 5.4265 1.680
5 8.8178 1.760 1.7725 49.6
6 -8.4804 2.640
7 -3.5532 0.560 1.834 37.2
8 -8.6972
T=1.156 1/f1.2=0.1241/f 1/f123=1.4734/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 8.
Embodiment 8
f = 10 FNo = 2.87 2w = 56012" Surface No. R D N V
1 4.7609 1.361 1.834 37.2
2 -20.7085 0.080
3 -10.0598 0.398 1.7847 26.2
4 4.6814 1.798
5 8.4970 1.870 1.713 53.9
6 -8.4970 3.342
7 -3.7758 0.557 1.834 37.2
8 -8.1532
T=1.196 1/f.2=0.0599/f 1/f1 .2.3=1.3523/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 9.
Claims (10)
1. A wide angle lens comprising a first lens group composed of a biconvex lens in which an intense convex surface is directed towards an object, a second lens group composed of a biconcave lens in which an intense concave surface is directed towards an image, a third lens group which is a biconvex lens, and a fourth lens group which is a negative meniscus in which a convex surface is directed towards an image, arranged in order from the object side, said wide angle lens being satisfied with the following conditions: -0.05/f < 1/fl.2 < 0.15/f 1.27/f < 1/fl.2.3 < 1.55/f 0.22f < Ds < 0.36 f
N1, N2, N4 > 1.75 N3 > 1.68 where
f : focal length of the whole system f12 : synthesized focal length of the first and second lens groups f1.2.3 : synthesized focal length of the first, second and third groups D5 : spacing between the third lens group and the fourth lens group
R7 : radius of curvature of the fourth lens group on the object side Ni : refractive index of niter of the ith lens group
2. A wide angle lens of claim 1, which is satisfied with
-0.4 f < R7 < -3.2 f where R7: radius of curvature of the fourth lens group on the object side.
3. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w = 57 30' Surface No. R D N V
1 4.8462 1.3550 1.834 37.2
2 -37.7386 0.116
3 -10.9661 0.3985 1.80518 25.4
4 5.3667 1.7934
5 8.4179 1.8970 1.7725 49.6
6 -8.4179 2.5905
7 -3.6498 0.5580 1.834 37.2
8 -8.3693
T=1.197 1/f1.2=0.0538/f 1/f1.2.3 1.4681/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 2.
4. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w =57024' Surface No. R D N V
1 4.7557 1.440 1.8044 39.6
2 -41.0084 0.120
3 -10.71 0.480 1.7847 26.2
4 5.2819 1.600
5 8.304 2.000 1.7725 49.6
6 -8.304 2.560
7 -3.6302 0.560 1.834 37.2
8 -8.0407
T=1.198 1/f1.2=0.041 5/f 1/f1.23= 1.452/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 3.
5. A lens of claim 2 having the following data:
f=10 FNo = 2.87 2w = 57031'
Surface No. R D N V
1 4.7667 1.36 1.834 37.2
2 -34.8295 0.112
3 -11.1529 0.40 1.80518 25.4
4 5.2834 1.80
5 8.48 - 2.08 1.7725 49.6
6 -8.48 > 2.44 7 -3.7396 0.56 1.834 37.2
8 -8.9658
T=1.199 1/f1 ,2=0.0982/f 1/f1 .2,3=1.4688/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 4.
6. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w =57"26' Surface No. R D N V
1 4.7929 1.440 1.834 37.2
2 -37.1508 0.112
3 -10.7251 0.480 1.80518 25.4
4 5.0617 1.600
5 8.8201 1.840 1.7725 49.6
6 -7.9615 2.720
7 -3.7125 0.56 1.834 37.2
8 -7.9804
T=1.195 1/f1,2=0.01 81/f 1/f1,2,3= 1.4300/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 5.
7. A lens of claim 2 having the following data:
f = 10 FNO = 2.87 2w = 57 32' Surface No. R D N V
1 4.7655 1.440 1.8044 39.6
2 -51.0659 0.120
3 -11.0890 0.480 1.7847 26.2
4 5.3157 1.60
5 8.0697 2.00 1.7725 49.6
6 -8.5244 2.56
7 -3.5572 0.56 1.8044 39.6
8 -7.9360
T=1.199 1f/f1.2=0.031 2/f 1/123=1.4500/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 6.
8. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w = 56026' Surface No. R D N V
1 5.0040 1.360 1.834 37.2
2 -25,5336 0.112
3 -10.2108 0.400 1.80518 25.4
4 5.5457 1.800
5 8.9361 1.760 1.7725 49.6
6 -8.8725 3.067
7 -3.6489 0.560 1.834 37.2
8 -8.3905
T=1.188 1/f1.2=0.09681/f 1/f1.2.3= 1.4143/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 7.
9. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w = 56 12' Surface No. R D N V
1 4.7376 1.360 1.834 37.2
2 -31.2778 0.112
3 -10.4125 0.400 1.80518 25.4
4 5.4265 1.680
5 8.8178 1.760 1.7725 49.6
6 -8.4804 2.640
7 -3.5532 0.560 1.834 37.2
8 -8.6972
T=1.156 1/f12=0.1241/f 1/fX 23=1.4734/f The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 8.
10. A lens of claim 2 having the following data:
f = 10 FNo = 2.87 2w = 56012'
Surface No. R D N V
1 4.7609 1.361 1.834 37.2
2 -20.7085 0.080
3 -10.0598 0.398 1.7847 26.2
4 4.6814 1.798
5 8.4970 1.870 1.713 53.9
6 -8.4970 3.342
7 -3.7758 0.557 1.834 37.2
8 -8.1532
T=1.196 1/f1 .2=0.0599/f 1/f1 .2.3=1.3523/f
The spherical aberration, astigmatism and distortion aberration curves are shown in Figure 9.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57174467A JPS5964809A (en) | 1982-10-06 | 1982-10-06 | Wide angle lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8326660D0 GB8326660D0 (en) | 1983-11-09 |
| GB2131198A true GB2131198A (en) | 1984-06-13 |
Family
ID=15978989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08326660A Withdrawn GB2131198A (en) | 1982-10-06 | 1983-10-05 | Wide angle lens having four lenses |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5964809A (en) |
| DE (1) | DE3336433A1 (en) |
| GB (1) | GB2131198A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5966251A (en) * | 1997-03-26 | 1999-10-12 | Fuji Photo Optical Co., Ltd. | Imaging lens |
| RU2183341C1 (en) * | 2000-10-26 | 2002-06-10 | Открытое акционерное общество "Красногорский завод им. С.А. Зверева" | Wide-aperture lens |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4688906A (en) * | 1985-12-30 | 1987-08-25 | Capitol Records | Three dimensional reflex lens systems |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB618360A (en) * | 1946-10-25 | 1949-02-21 | Eastman Kodak Co | Improvements in or relating to photographic objectives |
| GB1454044A (en) * | 1973-01-26 | 1976-10-27 | Minnesota Mining & Mfg | Camera |
| GB2036366A (en) * | 1978-11-28 | 1980-06-25 | Olympus Optical Co | Lens system having four elements |
-
1982
- 1982-10-06 JP JP57174467A patent/JPS5964809A/en active Granted
-
1983
- 1983-10-05 GB GB08326660A patent/GB2131198A/en not_active Withdrawn
- 1983-10-06 DE DE19833336433 patent/DE3336433A1/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB618360A (en) * | 1946-10-25 | 1949-02-21 | Eastman Kodak Co | Improvements in or relating to photographic objectives |
| GB1454044A (en) * | 1973-01-26 | 1976-10-27 | Minnesota Mining & Mfg | Camera |
| GB2036366A (en) * | 1978-11-28 | 1980-06-25 | Olympus Optical Co | Lens system having four elements |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5966251A (en) * | 1997-03-26 | 1999-10-12 | Fuji Photo Optical Co., Ltd. | Imaging lens |
| RU2183341C1 (en) * | 2000-10-26 | 2002-06-10 | Открытое акционерное общество "Красногорский завод им. С.А. Зверева" | Wide-aperture lens |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0250445B2 (en) | 1990-11-02 |
| JPS5964809A (en) | 1984-04-12 |
| GB8326660D0 (en) | 1983-11-09 |
| DE3336433A1 (en) | 1984-04-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |