JPH04335609A - Small-sized wide-angle lens - Google Patents
Small-sized wide-angle lensInfo
- Publication number
- JPH04335609A JPH04335609A JP3107321A JP10732191A JPH04335609A JP H04335609 A JPH04335609 A JP H04335609A JP 3107321 A JP3107321 A JP 3107321A JP 10732191 A JP10732191 A JP 10732191A JP H04335609 A JPH04335609 A JP H04335609A
- Authority
- JP
- Japan
- Prior art keywords
- lens
- lens component
- negative
- component
- positive
- 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.)
- Granted
Links
- 230000005499 meniscus Effects 0.000 claims abstract description 11
- 230000004075 alteration Effects 0.000 abstract description 36
- 230000014509 gene expression Effects 0.000 abstract description 18
- 239000002131 composite material Substances 0.000 abstract description 3
- 201000009310 astigmatism Diseases 0.000 description 12
- 238000010586 diagram Methods 0.000 description 12
- 230000000694 effects Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 230000002093 peripheral effect Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005282 brightening Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、３５ｍｍ判のコンパク
トなレンズシャッターカメラ及びレンジファインダー付
きカメラ等の使用に適した広角レンズに関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-angle lens suitable for use in 35 mm compact lens shutter cameras, cameras with rangefinders, and the like.
【０００２】0002
【従来の技術】従来より知られている負正負の屈折力配
分を有する対象型広角レンズのタイプとして、ビオゴン
型やアビオゴン型等が存在している。負正負の対称型で
あるビオゴン型広角レンズは，広い画角を包括でき、歪
曲収差を小さくおさえることができる。また、負正負の
屈折力配分をとることからトポゴン型広角レンズやオル
ソメータ型広角レンズ等に比べ、周辺光量を多くできる
という利点を有していた。そして、これらの基本的な型
式を発展させ、Ｆナンバーを明るくした例が、特開昭５
４−７０８２６号公報に、また最少枚数で構成した例が
、特公昭５１−２４８８６及び特開昭５６−１４０３１
１公報に示されている。2. Description of the Related Art Conventionally known types of symmetrical wide-angle lenses having negative, positive and negative refractive power distribution include the Biogon type and the Abiogon type. The Biogon wide-angle lens, which is a negative-positive-negative symmetrical lens, can cover a wide angle of view and can keep distortion to a small level. Furthermore, since it has a negative, positive and negative refractive power distribution, it has the advantage of being able to increase the amount of peripheral light compared to a topogon type wide-angle lens, an orthometer type wide-angle lens, etc. An example of developing these basic models and brightening the F number is the JP-A-5.
4-70826, and examples of configurations with the minimum number of sheets are published in Japanese Patent Publication No. 51-24886 and Japanese Patent Application Laid-open No. 56-14031.
This is shown in Publication No. 1.
【０００３】0003
【発明が解決しようとする課題】しかしながら、ビオゴ
ン型広角レンズは構成枚数が多く、レンズ系全厚（レン
ズの最も物体側の面から最も像側の面までの厚み）が厚
く、しかもＦナンバーが暗いという欠点を有していた。
また、特開昭５４−７０８２６号公報に示されているレ
ンズ系は、Ｆナンバーは明るいがレンズ系全厚が厚く、
構成枚数も多く、コンパクト化、低コスト化の点で十分
とはいえなかった。また、特公昭５１−２４８８６号公
報、特開昭５６−１４０３１１号公報に示されているレ
ンズ系は６枚構成であり、この型式のレンズ系としては
最低枚数で構成されている。しかし、レンズ系の全長が
長く、Ｆナンバーも暗く、好ましくなかった。[Problems to be Solved by the Invention] However, the Biogon type wide-angle lens has a large number of elements, the total thickness of the lens system (thickness from the surface closest to the object side to the surface closest to the image side), and the F number is large. It had the disadvantage of being dark. In addition, the lens system shown in Japanese Patent Application Laid-Open No. 54-70826 has a bright F number, but the total thickness of the lens system is thick.
The number of components was large, and it could not be said to be sufficient in terms of compactness and cost reduction. Further, the lens systems shown in Japanese Patent Publication No. 51-24886 and Japanese Patent Application Laid-open No. 56-140311 are composed of six lenses, which is the minimum number of lens systems of this type. However, the overall length of the lens system was long and the F number was dark, which was not desirable.
【０００４】本発明はこの様な従来の問題点を解決し、
レンズ系全厚の薄肉化、大口径化、構成枚数の軽減を実
現し、低コストでコンパクトな対称型広角レンズを提供
するものである。The present invention solves these conventional problems,
The overall thickness of the lens system has been reduced, the aperture has been increased, and the number of lenses has been reduced to provide a compact, symmetrical wide-angle lens at low cost.
【０００５】[0005]
【課題を解決する為の手段】物体側から順に、物体側に
凸面を向けた負メニスカスレンズの第１レンズ成分Ｌ１
、正レンズと負レンズの貼り合わせからなり物体側に
凸面を向けた接合正レンズの第２レンズ成分Ｌ２ 、負
レンズと正レンズの貼り合わせからなり像側に凸面を向
けた接合正レンズの第３レンズ成分Ｌ３ 、像側に凸面
を向けた負メニスカスレンズの第４レンズ成分Ｌ４ に
より構成され、前記第２レンズ成分Ｌ２ と前記第３レ
ンズ成分Ｌ３ との間に配置された絞りを有し、かつ以
下の条件を満足する。[Means for solving the problem] First lens component L1 of a negative meniscus lens having a convex surface facing the object side in order from the object side.
, a second lens component L2 of a cemented positive lens consisting of a positive lens and a negative lens bonded together with a convex surface facing the object side; a second lens component L2 of a cemented positive lens consisting of a negative lens and a positive lens bonded together with a convex surface facing the image side; 3 lens components L3, and a 4th lens component L4 which is a negative meniscus lens with a convex surface facing the image side, and has an aperture disposed between the second lens component L2 and the third lens component L3; and satisfy the following conditions.
【０００６】[0006]
【数４】[Math 4]
【０００７】ｔ１ ：前記第１レンズ成分Ｌ１ の最も
像側の面から前記第２レンズ成分
Ｌ２ の最も物体側の面までの軸上空気間隔ｔ３ ：前
記第３レンズ成分Ｌ３ の最も像側の面から前記第４レ
ンズ成分
Ｌ４ の最も物体側の面までの軸上空気間隔ｎ２１：前
記第２レンズ成分Ｌ２ 中の物体側の正レンズのｄ線に
対する屈折率
ｎ２２：前記第２レンズ成分Ｌ２ 中の像側の負レンズ
のｄ線に対する屈折率
ｎ３１：前記第３レンズ成分Ｌ３ 中の物体側の負レン
ズのｄ線に対する屈折率
ｎ３２：前記第３レンズ成分Ｌ３ 中の像側の正レンズ
のｄ線に対する屈折率
ｆ ：全系の焦点距離t1: On-axis air distance from the most image-side surface of the first lens component L1 to the most object-side surface of the second lens component L2 t3: The most image-side surface of the third lens component L3 axial air distance n21 from to the most object-side surface of the fourth lens component L4: refractive index n22 for the d-line of the object-side positive lens in the second lens component L2: Refractive index n31 for the d-line of the negative lens on the image side: Refractive index n32 for the d-line of the negative lens on the object side in the third lens component L3: d-line of the positive lens on the image side in the third lens component L3 refractive index f: focal length of the entire system
【０００８】[0008]
【作用】本発明においては第２レンズ成分Ｌ２ と第３
レンズ成分Ｌ３ とが正屈折力を有し、全体として負正
負の屈折力配置を有している。第１レンズ成分Ｌ１ 及
び第４レンズ成分Ｌ４ はそれぞれ、像面弯曲や非点収
差を十分に補正するために、絞りに対して凹面を向けた
負のメニスカスレンズで構成されている。前述した通り
、負のメニスカスレンズを用いることによって、画角を
より大きくすることが可能となり、周辺光量の増大にも
つながる。[Operation] In the present invention, the second lens component L2 and the third lens component L2
The lens component L3 has a positive refractive power, and the entire lens component has a negative-positive-negative refractive power arrangement. The first lens component L1 and the fourth lens component L4 are each composed of a negative meniscus lens with a concave surface facing the aperture in order to sufficiently correct field curvature and astigmatism. As mentioned above, by using a negative meniscus lens, it is possible to further increase the angle of view, which also leads to an increase in the amount of peripheral light.
【０００９】物体側から順に正レンズと負レンズの貼り
合わせレンズの第２レンズ成分Ｌ２ 、及び物体側から
順に負レンズと正レンズの貼り合わせレンズの第３レン
ズ成分Ｌ３ は、それぞれ球面収差を十分に補正できる
構成であり、歪曲収差等の収差補正も考慮し、絞りに対
して対称な形状とした。もし、第２レンズ成分Ｌ２ を
物体側から順に負レンズと正レンズの接合レンズ、第３
レンズ成分Ｌ３ を物体側から順に正レンズと負レンズ
の接合レンズにおきかえた場合、球面収差の補正が困難
になり、大口径化には不利である。また、本発明では、
各条件に示すごとく各レンズの空気間隔及び各レンズの
厚さの選択が重要である。The second lens component L2 of a composite lens consisting of a positive lens and a negative lens in order from the object side, and the third lens component L3 of a composite lens consisting of a negative lens and a positive lens in order from the object side, are designed to sufficiently compensate for spherical aberration. The lens is designed to be symmetrical with respect to the aperture, taking into consideration the correction of aberrations such as distortion. If the second lens component L2 is a cemented lens of a negative lens and a positive lens in order from the object side,
If the lens component L3 is replaced with a cemented lens of a positive lens and a negative lens in order from the object side, it becomes difficult to correct spherical aberration, which is disadvantageous for increasing the aperture. Furthermore, in the present invention,
As shown in each condition, it is important to select the air spacing between each lens and the thickness of each lens.
【００１０】次に各条件式についての説明をする。一般
に、負正負の絞りに対して対称性を持つビオゴン型の様
なレンズの場合、負の第１レンズ群（第１レンズ成分Ｌ
１ ）及び、最も像側の負のレンズ群（第４レンズ成分
Ｌ４）とその間の正のレンズ群との間の空気間隔（ｔ１
及びｔ３）は、広いほどペッツバール和を適切な値に
保つ自由度が増加する。そして、構成枚数の少ないレン
ズでも良好なペッツバール和を設定することが可能にな
り、非点収差や像面弯曲も小さくすることができる。し
かしながら、あまりにも前記空気間隔ｔ１ 及びｔ３
が大きいと、レンズ全厚が大きく、前玉径及び後玉径が
大きくなり、レンズ系全体の大型化につながり好ましく
ない。逆に前記空気間隔ｔ１ 及びｔ３ が非常に小さ
くなると、結果的にペッツバール和が正の方向へ変位し
、非点収差、像面弯曲の補正が困難となるばかりか、絞
りより離れたレンズにおいて軸上光線と軸外光線との分
離が悪くなるため、他の軸上収差も軸外収差の補正バラ
ンスを適切に保つことが困難になる。Next, each conditional expression will be explained. Generally, in the case of a biogon type lens which has symmetry with respect to a negative, positive and negative aperture, the negative first lens group (the first lens component L
1) and the air distance (t1) between the negative lens group closest to the image side (fourth lens component L4) and the positive lens group therebetween.
and t3), the wider the range, the greater the degree of freedom to maintain the Petzval sum at an appropriate value. Furthermore, it is possible to set a good Petzval sum even with a lens having a small number of lenses, and it is also possible to reduce astigmatism and field curvature. However, too said air spacing t1 and t3
If is large, the total lens thickness becomes large, and the front lens diameter and rear lens diameter become large, leading to an increase in the size of the entire lens system, which is undesirable. On the other hand, if the air distances t1 and t3 become extremely small, the Petzval sum will shift in the positive direction, making it difficult to correct astigmatism and field curvature. Since the separation between the upper ray and the off-axis ray becomes poor, it becomes difficult to maintain an appropriate balance of correction for other axial aberrations as well as off-axis aberrations.
【００１１】これらの原因になっているペッツバール和
は、正レンズと負レンズの適切な屈折率を設定すること
によってある程度改善することが可能である。特に接合
正レンズの第２レンズ成分Ｌ２ 及び第３レンズ成分Ｌ
３ の適切な屈折率の設定が必要となる。従って接合正
レンズの第２レンズ成分Ｌ２ 及び第３レンズ成分Ｌ３
中の正レンズには、負レンズよりも高屈折率のガラス
を使用し、ペッツバール和を小さくする。一般に正の屈
折力を有する貼り合わせレンズにおいて、正レンズに高
屈折率ガラスを用い、負レンズに低屈折率ガラスを用い
る場合、球面収差が補正できなくなり、Ｆナンバーを明
るくすることができない。本発明の場合、第１レンズ成
分Ｌ１ と第２レンズ成分のＬ２ の空気間隔ｔ１ 及
び第３レンズ成分Ｌ３ と第４レンズ成分Ｌ４ の空気
間隔ｔ３ に存在する空気レンズ等によって、球面収差
を補正し、Ｆナンバーを明るくすることができる。従っ
て、前記空気間隔ｔ１ 及びｔ３ と各レンズの屈折率
を決定すると同時に、適切な値にする必要がある。そし
て空気間隔ｔと屈折率ｎとの適切な比を保つことにより
、非点収差及び像面弯曲を悪化させることなく、前記空
気間隔ｔ１ 及びｔ３ を小さくすることができ、レン
ズの全厚を小さくすることができる。[0011] The Petzval sum, which is the cause of these problems, can be improved to some extent by setting appropriate refractive indexes for the positive lens and the negative lens. In particular, the second lens component L2 and the third lens component L of the cemented positive lens
It is necessary to set an appropriate refractive index of 3. Therefore, the second lens component L2 and the third lens component L3 of the cemented positive lens
The positive lens inside uses glass with a higher refractive index than the negative lens to reduce the Petzval sum. In general, in a laminated lens having positive refractive power, when a high refractive index glass is used for the positive lens and a low refractive index glass is used for the negative lens, spherical aberration cannot be corrected and the F number cannot be made bright. In the case of the present invention, spherical aberration is corrected by an air lens or the like existing at an air distance t1 between the first lens component L1 and the second lens component L2 and an air distance t3 between the third lens component L3 and the fourth lens component L4. , it is possible to brighten the F number. Therefore, it is necessary to determine the air distances t1 and t3 and the refractive index of each lens, and at the same time set them to appropriate values. By maintaining an appropriate ratio between the air spacing t and the refractive index n, the air spacings t1 and t3 can be reduced without worsening astigmatism and field curvature, and the total thickness of the lens can be reduced. can do.
【００１２】条件式（１）、（２）はレンズのコンパク
ト化と軸外収差、特に非点収差及び像面弯曲の補正に関
する条件である。
条件式（１）の下限を下まわる時、以下の２通りの場合
が考えられる。
■ 第２レンズ成分Ｌ２ 中の正レンズと負レンズの
屈折率差が非常に小さい場合。
■ 第１レンズ成分Ｌ１ と第２レンズ成分Ｌ２ の
間の空気間隔ｔ１ が、非常に大きい場合。Conditional expressions (1) and (2) are conditions regarding making the lens compact and correcting off-axis aberrations, particularly astigmatism and field curvature. When the lower limit of conditional expression (1) is exceeded, the following two cases can be considered. ■ When the difference in refractive index between the positive lens and the negative lens in the second lens component L2 is very small. (2) When the air distance t1 between the first lens component L1 and the second lens component L2 is very large.
【００１３】■の場合は、ペッツバール和が大きく正の
値をとるために非点収差及び像面弯曲の補正が困難とな
る。■の場合はレンズの全厚Ｄが大きくなり、レンズの
前玉径、後玉径も増大し大型化するので好ましくない。
条件式（１）の上限を上まわる時、以下の２通りの場合
が考えられる。
■ 第２レンズ成分Ｌ２ の中の正レンズと負レンズ
の屈折率差が非常に大きい場合。
■ 第１レンズ成分Ｌ１ と第２レンズ成分Ｌ２ と
の間の空気間隔ｔ１ が非常に小さい場合。In case (2), the Petzval sum is large and takes a positive value, making it difficult to correct astigmatism and field curvature. In case (2), the total thickness D of the lens increases, and the diameters of the front and rear lenses also increase, making the lens larger, which is not preferable. When the upper limit of conditional expression (1) is exceeded, the following two cases can be considered. ■ When the difference in refractive index between the positive lens and the negative lens in the second lens component L2 is very large. (2) When the air distance t1 between the first lens component L1 and the second lens component L2 is very small.
【００１４】■の場合、ペッツバール和には有効である
が、結果的に接合された正・負レンズの分散の差が少な
くなり、色収差の補正が困難となり好ましくない。また
、球面収差の補正も困難になりＦナンバーを明るくでき
なくなる。■の場合、絞りより離れたレンズにおいて軸
外光線と軸上光線との分離が悪くなるため、軸外収差と
軸上収差の収差補正のバランスが悪化し、特に非点収差
及び像面弯曲が補正困難となり、さらにサジタル像面が
大きく弯曲してしまう。そのため、良好な性能は得られ
ない。したがって、この範囲が望ましい。ましい。In the case of (2), although it is effective for Petzval sum, the difference in dispersion between the cemented positive and negative lenses becomes small as a result, making it difficult to correct chromatic aberration, which is not preferable. Furthermore, it becomes difficult to correct spherical aberration, making it impossible to make the F number brighter. In the case of (2), the separation of off-axis and on-axis rays deteriorates in a lens that is far from the aperture, which worsens the balance between off-axis and on-axis aberration correction, and particularly reduces astigmatism and field curvature. Correction becomes difficult, and the sagittal image plane becomes greatly curved. Therefore, good performance cannot be obtained. Therefore, this range is desirable. Delicious.
【００１５】条件（２）の下限を下まわる時、以下の２
通りの場合が考えられる。
■ 第３レンズ成分Ｌ３ 中の負レンズ、正レンズの
屈折率差が非常に小さい場合■ 第３レンズ成分Ｌ３
と第４レンズ成分Ｌ４ との間の空気間隔ｔ３ が非
常に大きい場合。■の場合は、ペッツバール和がより大
きく正の値をとるため、非点収差及び像面弯曲の補正が
困難になる。
■の場合は、レンズの全厚が大きくなり、レンズの前玉
径、後玉径も増大し、レンズ系全体の大型化をまねき好
ましくない。又コストアップにもつながり好ましくない
。[0015] When the lower limit of condition (2) is below, the following two
A possible case is a street. ■ When the refractive index difference between the negative and positive lenses in the third lens component L3 is very small ■ The third lens component L3
and the fourth lens component L4 is very large. In case (2), the Petzval sum is larger and takes a positive value, making it difficult to correct astigmatism and field curvature. In case (2), the total thickness of the lens becomes large, and the diameters of the front and rear lenses also increase, which leads to an increase in the size of the entire lens system, which is not preferable. This is also undesirable as it leads to increased costs.
【００１６】条件（２）の上限を上まわる時、以下の２
通りの場合が考えられる。
■ 第３レンズ成分Ｌ３ 中の負レンズ・正レンズの
屈折率差が非常に大きい場合。■ 第３レンズ成分Ｌ
３ と第４レンズ成分Ｌ４ の間の空気間隔ｔ３ が非
常に小さい場合がある。[0016] When the upper limit of condition (2) is exceeded, the following 2
A possible case is a street. ■ When the difference in refractive index between the negative and positive lenses in the third lens component L3 is extremely large. ■ Third lens component L
3 and the fourth lens component L4 may be very small.
【００１７】■の場合、ペッツバール和には有効である
が、接合された負レンズの分散の差が少なくなり、色収
差の補正が困難となり、好ましくない。また、球面収差
の補正も困難になり、Ｆナンバーを明るくすることがで
きなくなる。■の場合、絞りより離れたレンズにおいて
軸外光線と軸上光線との分離が悪くなり、軸外収差と軸
上収差との収差補正のバランスが悪化し、特に非点収差
、及び像面弯曲が補正困難になり、さらにサジタル像面
が大きく弯曲する様になり、良好な性能は得られない。
本発明の効果を十分発揮させるためには、下限を０．８
５とすればより良い結果が得られる。In the case of (2), although it is effective for Petzval sum, the difference in dispersion between the cemented negative lenses decreases, making it difficult to correct chromatic aberration, which is not preferable. Furthermore, it becomes difficult to correct spherical aberration, making it impossible to increase the F number. In the case of (2), the separation of off-axis and on-axis rays becomes worse in the lens located further away from the aperture, and the balance of aberration correction between off-axis and on-axis aberrations deteriorates, especially astigmatism and field curvature. becomes difficult to correct, and furthermore, the sagittal image plane becomes largely curved, making it impossible to obtain good performance. In order to fully exhibit the effects of the present invention, the lower limit must be set to 0.8
A value of 5 will give better results.
【００１８】以上の如き本発明の構成において、以下の
ごとき条件式（３）及び（４）を満たすことが望ましい
。In the configuration of the present invention as described above, it is desirable that the following conditional expressions (3) and (4) be satisfied.
【００１９】[0019]
【数５】[Math 5]
【００２０】Ｄ ：レンズの最も物体側の面から最も
像側の面までの軸上距離
ｔ２ ：正レンズと負レンズの貼り合わせからなり物体
側に凸面を向けた
接合正レンズの第２レンズ成分Ｌ２ の最も像側の面か
ら負レンズと正レンズの貼り合わせからなり像側に凸面
を向けた接合正レンズの第３レンズ成分Ｌ３ の最も物
体側の面までの軸上空気間隔
条件式（３）は、第１レンズ成分Ｌ１ と第２レンズ成
分Ｌ２ との間の空気間隔ｔ１ 及び第３レンズ成分Ｌ
３ と第４レンズ成分Ｌ４ との間の空気間隔ｔ３ と
の合成された空気間隔を更に規定する条件である。条件
式（３）の下限を下まわると、レンズの全厚は小さくな
るが、軸上光線と軸外光線との分離が難しくなり、収差
補正の自由度が不足してしまい、結果的に非点収差、像
面弯曲が悪化する。そして、各レンズが物理的に干渉す
る可能性も発生し、好ましくない。逆に上限を上まわる
と、球面収差の補正に利用している空気レンズの作用が
弱まるので好ましくないばかりか、レンズの全厚が厚く
なるのでコンパクト化に反し好ましくない。尚、本発明
の効果を発揮するには、下限を０．０８とし、上限を０
．３４にすると更に良好な結果が得られる。D: Axial distance t2 from the surface closest to the object side of the lens to the surface closest to the image side: Second lens component of a cemented positive lens consisting of a positive lens and a negative lens, with the convex surface facing the object side. The axial air distance conditional expression (3 ) is the air distance t1 between the first lens component L1 and the second lens component L2 and the third lens component L
3 and the air distance t3 between the fourth lens component L4. When the lower limit of conditional expression (3) is below, the total thickness of the lens becomes smaller, but it becomes difficult to separate axial rays and off-axis rays, and the degree of freedom for correcting aberrations is insufficient, resulting in non-standard performance. Point aberration and field curvature worsen. Additionally, there is a possibility that the lenses may physically interfere with each other, which is not preferable. On the other hand, if it exceeds the upper limit, this is not only undesirable because the effect of the air lens used to correct spherical aberration is weakened, but also the total thickness of the lens becomes thick, which is undesirable because it goes against the grain of compactness. In addition, in order to exhibit the effect of the present invention, the lower limit should be 0.08 and the upper limit should be 0.
．． Even better results can be obtained by setting it to 34.
【００２１】条件（４）は第２レンズ成分Ｌ２ と第３
レンズ成分Ｌ３ の間の空気間隔ｔ２ を規定するもの
である。本発明を、コンパクトなレンズシャッターカメ
ラやいわゆるコンパクトカメラ等に用いる場合、第２レ
ンズ成分Ｌ２ と第３レンズ成分Ｌ３ との間にシャッ
ター及び絞りＳを入れる必要があり、ある一定以上の空
気間隔が必要である。従って下限を下まわると、シャッ
ター及び絞りが構造上入らなくなる。逆に上限をこえる
と、最大画角の斜光線の入射する位置が各レンズ面のよ
り光軸から離れた部分になり、周辺光量の低下につなが
る。それを補うために有効径を大きくすれば、レンズ全
体の大型化につながり好ましくない。しかも、周辺斜光
線の屈折角が大きくなるので高次収差が発生し、特に軸
外収差が悪化し好ましくない。更に本発明の効果を発揮
させるには下限を０．１ とし、上限を０．３５とする
とより良好な結果がえられる。Condition (4) is the second lens component L2 and the third lens component L2.
This defines the air distance t2 between the lens components L3. When the present invention is used in a compact lens shutter camera or a so-called compact camera, it is necessary to insert a shutter and an aperture S between the second lens component L2 and the third lens component L3, and an air gap of more than a certain level is required. is necessary. Therefore, below the lower limit, the shutter and diaphragm will not fit structurally. On the other hand, when the upper limit is exceeded, the incident position of the oblique ray at the maximum angle of view becomes a part of each lens surface that is further away from the optical axis, leading to a decrease in the amount of peripheral light. Increasing the effective diameter to compensate for this would lead to an increase in the size of the entire lens, which is undesirable. Furthermore, since the refraction angle of the peripheral oblique ray becomes large, higher-order aberrations occur, and in particular, off-axis aberrations worsen, which is undesirable. Furthermore, in order to exhibit the effects of the present invention, better results can be obtained by setting the lower limit to 0.1 and setting the upper limit to 0.35.
【００２２】本発明においては、更に次のような条件式
（５）及び（７）を満たすことが望ましい。In the present invention, it is further desirable that the following conditional expressions (5) and (7) be satisfied.
【００２３】[0023]
【数６】[Math 6]
【００２４】ｄ２１：正レンズと負レンズの貼り合わせ
からなり物体側に凸面を向けた接合正レンズの第２レン
ズ成分Ｌ２ 中の物体側正レンズの中心厚ｄ３２：負レ
ンズと正レンズの貼り合わせからなり像側に凸面を向け
た接合正レンズの第３レンズ成分Ｌ３ 中の像側の正レ
ンズの中心厚
条件式（５）はレンズの全厚Ｄ即ち、第１レンズ成分Ｌ
１ の最も物体側の面から、第４レンズ成分Ｌ４ の最
も像側の面までの全厚を規定する条件である。本発明は
、一般的な対称型レンズに比べバックフォーカスは長い
がレンズの全厚Ｄは小さい。言い換えれば、レンズ全長
（レンズの全厚Ｄ＋バックフォーカス）は比較的大きく
、レンズの全厚が小さいのが特徴である。これはコンパ
クトなレンズシャッターカメラやレンジファインダー付
カメラ等に組み入れる時に、沈胴式にすればコンパクト
に収納することが出き、レンズの全厚が小さい方が現実
的に有効である。条件式（５）の下限を下まわると、絞
りよりはなれたレンズにおいて軸上光線と軸外光線との
分離が悪くなり、各収差の補正バランスがとれなくなり
、Ｆ２．８ 程度の明るさを実現しつつ広角化すること
が困難になる。又、上限を上まわると、収差補正上は有
利な方向であるがレンズの全厚が大きくなり、本発明の
目的からはずれ好ましくない。又、本発明の効果を十分
発揮するためには下限を０．５５、上限を１．２ とす
ればさらに良い結果が得られる。d21: Second lens component L2 of a cemented positive lens consisting of a positive lens and a negative lens, with the convex surface facing the object side. d32: Center thickness of the object side positive lens in the second lens component L2: A negative lens and a positive lens bonded together. The third lens component L3 is a cemented positive lens with a convex surface facing the image side.
This condition defines the total thickness from the surface closest to the object side of L4 to the surface closest to the image side of the fourth lens component L4. The present invention has a longer back focus than a general symmetrical lens, but the total thickness D of the lens is small. In other words, the lens is characterized in that the total length (total lens thickness D+back focus) is relatively large and the total lens thickness is small. When this lens is incorporated into a compact lens shutter camera or a camera with a rangefinder, it can be stored compactly by making it collapsible, and it is actually more effective if the overall thickness of the lens is small. When the lower limit of conditional expression (5) is below, the separation of axial rays and off-axis rays becomes poor in the lens located far from the aperture, and the correction balance of each aberration cannot be maintained, resulting in a brightness of about F2.8. It becomes difficult to widen the angle of view at the same time. On the other hand, if it exceeds the upper limit, although this is advantageous in terms of aberration correction, the total thickness of the lens increases, which is not preferable as it deviates from the object of the present invention. Further, in order to fully exhibit the effects of the present invention, even better results can be obtained by setting the lower limit to 0.55 and the upper limit to 1.2.
【００２５】条件式（６）、（７）は接合された正レン
ズの第２レンズ成分Ｌ２ 及び第３レンズ成分Ｌ３ 中
の正レンズの中心厚に関する条件である。これら正レン
ズの中心厚は、特に球面収差の補正に有効に作用してい
る。
本発明のごとくＦ２．８ 程度とこのタイプとしては大
口径比のレンズを実現するには、軸外収差以外にも球面
収差の良好な補正が必要になる。Conditional expressions (6) and (7) are conditions regarding the center thickness of the positive lens in the second lens component L2 and third lens component L3 of the cemented positive lens. The center thickness of these positive lenses is particularly effective in correcting spherical aberration. In order to realize a lens with a large aperture ratio of approximately F2.8 as in the present invention, it is necessary to properly correct spherical aberrations in addition to off-axis aberrations.
【００２６】条件式（６）の下限を下まわると球面収差
の補正が困難となり、また結果的に接合された第２レン
ズ成分Ｌ２ の中の正レンズの縁厚が薄くなるので製造
上好ましくない。逆に上限を上まわると、接合された第
２レンズ成分Ｌ２ の中の正レンズの中心厚が非常に大
きくなる。従って球面収差の補正には良いが、レンズの
全厚Ｄが大きくなり各レンズの径の大型化し、結果的に
レンズ全体の大型化につながり好ましくない。従って、
現実的にはこの範囲が望ましい。If the lower limit of conditional expression (6) is not reached, it becomes difficult to correct spherical aberration, and as a result, the edge thickness of the positive lens in the cemented second lens component L2 becomes thinner, which is unfavorable in terms of manufacturing. . On the other hand, if it exceeds the upper limit, the center thickness of the positive lens in the cemented second lens component L2 becomes very large. Therefore, although it is good for correcting spherical aberration, the total thickness D of the lens becomes large and the diameter of each lens becomes large, which is undesirable because it results in an increase in the size of the entire lens. Therefore,
This range is realistically desirable.
【００２７】条件式（７）の下限を下まわると、球面収
差の良好な補正が困難になる。又、結果的に接合された
第３レンズ成分の中の正レンズの縁厚が薄くなるので、
製造上好ましくない。又、逆に上限を上まわると、接合
された第３レンズ成分Ｌ３ の中の正レンズの中心厚が
非常に大きく、レンズ全厚Ｄが大きくなる。そのため、
各レンズの径が大型化し、結果的にレンズ全体の大型化
を招き好ましくない。又、非常に中心厚が厚いと、製造
上も困難となり、コストアップにつながり好ましくない
。When the lower limit of conditional expression (7) is exceeded, it becomes difficult to satisfactorily correct spherical aberration. Also, as a result, the edge thickness of the positive lens in the cemented third lens component becomes thinner.
Unfavorable for manufacturing. On the other hand, when the upper limit is exceeded, the center thickness of the positive lens in the cemented third lens component L3 becomes very large, and the total lens thickness D becomes large. Therefore,
This increases the diameter of each lens, resulting in an increase in the size of the entire lens, which is undesirable. Further, if the center thickness is extremely thick, it becomes difficult to manufacture, leading to an increase in cost, which is undesirable.
【００２８】更に、本発明に以下の条件を付加すればよ
り良好な結果が得られる。Furthermore, better results can be obtained by adding the following conditions to the present invention.
【００２９】[0029]
【数７】[Math 7]
【００３０】ｑ１ ：第１レンズ成分Ｌ２ の形状因子
ｑ４ ：第４レンズ成分Ｌ４ の形状因子尚、形状因子
ｑの式を以下に示す。q1: Shape factor of the first lens component L2 q4: Shape factor of the fourth lens component L4 The formula for the shape factor q is shown below.
【００３１】[0031]
【数８】[Math. 8]
【００３２】ｒ１ ：物体側レンズ面の曲率半径ｒ２
：像側レンズ面の曲率半径
条件式（８）、（９）は、最も物体側のレンズ成分と最
も像側のレンズ成分の形状に関する式である。そして、
（１０） は形状因子ｑを求める式である。r1: radius of curvature r2 of the object side lens surface
: The radius of curvature of the image side lens surface conditional expressions (8) and (9) are expressions regarding the shapes of the lens component closest to the object side and the lens component closest to the image side. and,
(10) is the formula for determining the shape factor q.
【００３３】条件式（８）の下限を下まわると、第１レ
ンズ成分Ｌ１ の各面の曲率半径が非常に小さくなるた
めに製造上困難になるばかりか、第１レンズ成分Ｌ１
と第２レンズ成分Ｌ２ との間の空気間隔ｔ１ が結果
的に大きくなり好ましくない。逆に上限を上まわる場合
、軸外光線に対し、第一面での屈折が大きくなり、結果
的に像面弯曲および非点収差が悪化する。If the lower limit of conditional expression (8) is not reached, the radius of curvature of each surface of the first lens component L1 becomes very small, which not only makes it difficult to manufacture, but also makes it difficult to manufacture the first lens component L1.
As a result, the air distance t1 between the lens component L2 and the second lens component L2 becomes large, which is not preferable. Conversely, when the upper limit is exceeded, refraction of off-axis rays at the first surface becomes large, resulting in worsening of field curvature and astigmatism.
【００３４】条件式（９）の下限を下まわると、軸外光
線に対し、第４レンズ成分Ｌ４ の最後面での屈折が非
常に大きくなり、結果的に像面弯曲および非点収差が悪
化する。逆に上限を上まわれば、第４レンズ成分の各面
の曲率半径が小さくなり、製造上困難になるばかりか、
第３レンズ成分Ｌ３ との間の空気間隔ｔ３ が結果的
に大きくなるため、コンパクト化に反し好ましくない。
したがって現実的にはこの範囲が好ましい。When the lower limit of conditional expression (9) is exceeded, the refraction of off-axis rays at the rearmost surface of the fourth lens component L4 becomes extremely large, resulting in worsening of field curvature and astigmatism. do. On the other hand, if it exceeds the upper limit, the radius of curvature of each surface of the fourth lens component becomes small, which not only makes it difficult to manufacture, but also
As a result, the air distance t3 between the third lens component L3 and the third lens component L3 becomes large, which is undesirable because it goes against compactness. Therefore, this range is actually preferable.
【００３５】[0035]
【実施例】第１実施例から第６実施例は、物体側から順
に物体側に凸面を向けた負メニスカスレンズの第１レン
ズ成分Ｌ１ 、正レンズと負レンズの貼り合わせからな
り物体側に凸面を向けた接合正レンズの第２レンズ成分
Ｌ２、負レンズと正レンズの貼り合わせからなり像側に
凸面を向けた接合正レンズの第３レンズ成分Ｌ３ 、像
側に凸面を向けた負メニスカスレンズの第４レンズ成分
Ｌ４ により構成され、前記第２レンズ成分Ｌ２ と前
記第３レンズ成分Ｌ３ との間に配置された絞りを有す
る。[Example] In the first to sixth embodiments, the first lens component L1 is a negative meniscus lens with a convex surface facing the object side in order from the object side, and the first lens component L1 is a negative meniscus lens with a positive lens and a negative lens bonded together and has a convex surface facing the object side. The second lens component L2 is a cemented positive lens with a convex surface facing the image side, and the third lens component L3 is a cemented positive lens consisting of a negative lens and a positive lens with a convex surface facing the image side.A negative meniscus lens with a convex surface facing the image side. , and has an aperture disposed between the second lens component L2 and the third lens component L3.
【００３６】以下に本発明の各実施例の諸元の値を掲げ
る。実施例の諸元表中における左端の数字は、物体側か
らの順序を表し、ｒはレンズ面の曲率半径、ｄはレンズ
面間隔、屈折率ｎ及びアッベ数νはｄ線（λ＝５８７．
６ｎｍ）に対する値である。The values of the specifications of each embodiment of the present invention are listed below. The leftmost number in the specification table of the example indicates the order from the object side, r is the radius of curvature of the lens surface, d is the distance between lens surfaces, refractive index n and Abbe number ν are the d-line (λ = 587.
6 nm).
【００３７】[0037]
【実施例１】ｆ＝２８．６ ＦＮＯ＝２．９０ ２ω＝７５．３°[Example 1] f=28.6 FNO=2.90 2ω=75.3°
【００３８】[0038]
【数９】[Math. 9]
【００３９】[0039]
【実施例２】ｆ＝２８．６ ＦＮＯ＝２．９０ ２ω＝７５．３°[Example 2] f=28.6 FNO=2.90 2ω=75.3°
【００４０】[0040]
【数１０】[Math. 10]
【００４１】[0041]
【実施例３】ｆ＝２８．６ ＦＮＯ＝２．８３ ２ω＝７５．１°[Example 3] f=28.6 FNO=2.83 2ω=75.1°
【００４２】[0042]
【数１１】[Math. 11]
【００４３】[0043]
【実施例４】ｆ＝２８．６ ＦＮＯ＝２．９０ ２ω＝７４．６°[Example 4] f=28.6 FNO=2.90 2ω=74.6°
【００４４】[0044]
【数１２】[Math. 12]
【００４５】[0045]
【実施例５】ｆ＝２８．６ ＦＮＯ＝２．９０ ２ω＝７４．９°[Example 5] f=28.6 FNO=2.90 2ω=74.9°
【００４６】[0046]
【数１３】[Math. 13]
【００４７】[0047]
【実施例６】ｆ＝２８．６ ＦＮＯ＝２．９０ ２ω＝７４．９°[Example 6] f=28.6 FNO=2.90 2ω=74.9°
【００４８】[0048]
【数１４】[Math. 14]
【００４９】尚、本発明の第１レンズ成分Ｌ１ または
第４レンズ成分Ｌ４ に非球面レンズを導入すれば、更
に非点収差や像面湾曲が良好にでき、さらに広角化でき
る。
また、第２レンズ成分Ｌ２ または第３レンズ成分Ｌ３
に非球面レンズを導入することにより更に球面収差を
補正でき、より大口径化することが可能であることは一
般的な非球面レンズの使用方法から言うまでもない。If an aspherical lens is introduced into the first lens component L1 or the fourth lens component L4 of the present invention, astigmatism and field curvature can be further improved, and the angle of view can be further widened. Also, the second lens component L2 or the third lens component L3
It goes without saying from the general usage of aspherical lenses that by introducing an aspherical lens into the lens, it is possible to further correct spherical aberration and increase the aperture.
【００５０】[0050]
【発明の効果】以上の如く本発明によれば、非常に少な
いレンズ構成枚数でＦ２．８ 程度の明るい広角レンズ
を実現することができ、コンパクトなレンズシャッター
式カメラやレンジファインダー付カメラ等に適用できる
。また、レンズの全厚が小さいのでカメラボディの中に
沈胴する方式をとれば、更にレンズの全厚が非常に薄く
なる。また、本発明は３５ｍｍ判カメラに限られず、大
判カメラ用レンズ等にも使用が可能である。[Effects of the Invention] As described above, according to the present invention, a bright wide-angle lens of approximately F2.8 can be realized with a very small number of lens components, and is applicable to compact lens-shutter cameras, cameras with rangefinders, etc. can. Furthermore, since the total thickness of the lens is small, if a method is adopted in which the lens is retracted into the camera body, the total thickness of the lens becomes even thinner. Furthermore, the present invention is not limited to 35 mm cameras, but can also be used for lenses for large format cameras, etc.
【図１】本発明の実施例１のレンズ構成図FIG. 1: Lens configuration diagram of Example 1 of the present invention
【図２】本発
明の実施例１の収差図[Fig. 2] Aberration diagram of Example 1 of the present invention
【図３】本発明の実施例２のレンズ構成図FIG. 3: Lens configuration diagram of Example 2 of the present invention
【図４】本発
明の実施例２の収差図[Fig. 4] Aberration diagram of Example 2 of the present invention
【図５】本発明の実施例３のレンズ構成図FIG. 5: Lens configuration diagram of Example 3 of the present invention
【図６】本発
明の実施例３の収差図[Fig. 6] Aberration diagram of Example 3 of the present invention
【図７】本発明の実施例４のレンズ構成図FIG. 7: Lens configuration diagram of Example 4 of the present invention
【図８】本発
明の実施例４の収差図[Fig. 8] Aberration diagram of Example 4 of the present invention
【図９】本発明の実施例５のレンズ構成図FIG. 9: Lens configuration diagram of Example 5 of the present invention
【図１０】本
発明の実施例５の収差図FIG. 10: Aberration diagram of Example 5 of the present invention
【図１１】本発明の実施例６のレンズ構成図FIG. 11: Lens configuration diagram of Example 6 of the present invention
【図１２】
本発明の実施例６の収差図[Figure 12]
Aberration diagram of Example 6 of the present invention
Ｌ１，Ｌ２，Ｌ３，Ｌ４ ・・・各レンズ成分Ｓ・・・
絞りL1, L2, L3, L4...Each lens component S...
aperture
Claims (2)
た負メニスカスレンズの第１レンズ成分Ｌ１ 、正レン
ズと負レンズの貼り合わせからなり物体側に凸面を向け
た接合正レンズの第２レンズ成分Ｌ２ 、負レンズと正
レンズの貼り合わせからなり像側に凸面を向けた接合正
レンズの第３レンズ成分Ｌ３ 、像側に凸面を向けた負
メニスカスレンズの第４レンズ成分Ｌ４ により構成さ
れ、前記第２レンズ成分Ｌ２ と前記第３レンズ成分Ｌ
３ との間に配置された絞りを有し、かつ以下の条件を
満足することを特徴とする小型の広角レンズ。 【数１】 ｔ１ ：前記第１レンズ成分Ｌ１ の最も像側の面から
前記第２レンズ成分 Ｌ２ の最も物体側の面までの軸上空気間隔ｔ３ ：前
記第３レンズ成分Ｌ３ の最も像側の面から前記第４レ
ンズ成分 Ｌ４ の最も物体側の面までの軸上空気間隔ｎ２１：前
記第２レンズ成分Ｌ２ 中の物体側の正レンズのｄ線に
対する屈折率 ｎ２２：前記第２レンズ成分Ｌ２ 中の像側の負レンズ
のｄ線に対する屈折率 ｎ３１：前記第３レンズ成分Ｌ３ 中の物体側の負レン
ズのｄ線に対する屈折率 ｎ３２：前記第３レンズ成分Ｌ３ 中の像側の正レンズ
のｄ線に対する屈折率 ｆ ：全系の焦点距離1. In order from the object side, a first lens component L1 of a negative meniscus lens with a convex surface facing the object side, a second lens component L1 of a cemented positive lens consisting of a bonded positive lens and a negative lens with a convex surface facing the object side. A third lens component L2 is a cemented positive lens consisting of a negative lens and a positive lens and has a convex surface facing the image side, and a fourth lens component L4 is a negative meniscus lens with a convex surface facing the image side. , the second lens component L2 and the third lens component L
3. A small wide-angle lens characterized by having an aperture disposed between and satisfying the following conditions. [Equation 1] t1: On-axis air distance from the most image-side surface of the first lens component L1 to the most object-side surface of the second lens component L2 t3: The most image-side surface of the third lens component L3 On-axis air distance n21 from the surface to the most object-side surface of the fourth lens component L4: Refractive index n22 for the d-line of the object-side positive lens in the second lens component L2: Medium of the second lens component L2 refractive index n31 for the d-line of the image-side negative lens in the third lens component L3: refractive index n32 for the d-line of the object-side negative lens in the third lens component L3: d of the image-side positive lens in the third lens component L3 Refractive index for the line f: Focal length of the entire system
下の条件を満足することを特徴とする小型の広角レンズ
。 【数２】 Ｄ ：レンズの最も物体側の面から最も像側の面まで
の軸上距離 ｔ２ ：前記第２レンズ成分Ｌ２ の最も像側の面から
前記第３レンズ成分 Ｌ３ の最も物体側の面までの軸上空気間隔【請求項３
】 請求項２記載の広角レンズにおいて以下の条件を
満足することを特徴とする小型の広角レンズ。 【数３】 ｄ２１：前記第２レンズ成分Ｌ２ 中の物体側正レンズ
の中心厚 ｄ３２：前記第３レンズ成分Ｌ３ 中の像側の正レンズ
の中心厚2. A compact wide-angle lens according to claim 1, characterized in that the wide-angle lens satisfies the following conditions. [Equation 2] D: Axial distance t2 from the most object-side surface of the lens to the most image-side surface t2: Axial distance from the most image-side surface of the second lens component L2 to the most object-side surface of the third lens component L3 On-axis air gap to the surface [Claim 3
A compact wide-angle lens according to claim 2, characterized in that the wide-angle lens satisfies the following conditions. [Equation 3] d21: Center thickness of the object-side positive lens in the second lens component L2 d32: Center thickness of the image-side positive lens in the third lens component L3
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3107321A JP3038974B2 (en) | 1991-05-13 | 1991-05-13 | Small wide-angle lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3107321A JP3038974B2 (en) | 1991-05-13 | 1991-05-13 | Small wide-angle lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04335609A true JPH04335609A (en) | 1992-11-24 |
| JP3038974B2 JP3038974B2 (en) | 2000-05-08 |
Family
ID=14456103
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3107321A Expired - Lifetime JP3038974B2 (en) | 1991-05-13 | 1991-05-13 | Small wide-angle lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3038974B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005266771A (en) * | 2004-02-18 | 2005-09-29 | Fujinon Corp | Image reading lens and image reader |
| JP2006285158A (en) * | 2005-03-10 | 2006-10-19 | Fujinon Corp | Image-reading lens and image reader |
| JP2009216858A (en) * | 2008-03-10 | 2009-09-24 | Fujinon Corp | Imaging lens and imaging apparatus |
| WO2012057021A1 (en) * | 2010-10-25 | 2012-05-03 | 富士フイルム株式会社 | Image capture optical assembly and image capture device |
| US10670833B2 (en) | 2017-05-08 | 2020-06-02 | Largan Precision Co., Ltd. | Imaging lens assembly, imaging apparatus and electronic device |
-
1991
- 1991-05-13 JP JP3107321A patent/JP3038974B2/en not_active Expired - Lifetime
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005266771A (en) * | 2004-02-18 | 2005-09-29 | Fujinon Corp | Image reading lens and image reader |
| JP4699032B2 (en) * | 2004-02-18 | 2011-06-08 | 富士フイルム株式会社 | Image reading lens and image reading apparatus |
| JP2006285158A (en) * | 2005-03-10 | 2006-10-19 | Fujinon Corp | Image-reading lens and image reader |
| JP4738879B2 (en) * | 2005-03-10 | 2011-08-03 | 富士フイルム株式会社 | Image reading lens and image reading apparatus |
| JP2009216858A (en) * | 2008-03-10 | 2009-09-24 | Fujinon Corp | Imaging lens and imaging apparatus |
| WO2012057021A1 (en) * | 2010-10-25 | 2012-05-03 | 富士フイルム株式会社 | Image capture optical assembly and image capture device |
| JPWO2012057021A1 (en) * | 2010-10-25 | 2014-05-12 | 富士フイルム株式会社 | Imaging optical system and imaging apparatus |
| JP5690354B2 (en) * | 2010-10-25 | 2015-03-25 | 富士フイルム株式会社 | Imaging optical system and imaging apparatus |
| US9395515B2 (en) | 2010-10-25 | 2016-07-19 | Fujifilm Corporation | Imaging optical system and imaging device |
| US10670833B2 (en) | 2017-05-08 | 2020-06-02 | Largan Precision Co., Ltd. | Imaging lens assembly, imaging apparatus and electronic device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3038974B2 (en) | 2000-05-08 |
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