JP2984484B2 - Rear focus zoom lens - Google Patents
Rear focus zoom lensInfo
- Publication number
- JP2984484B2 JP2984484B2 JP4303929A JP30392992A JP2984484B2 JP 2984484 B2 JP2984484 B2 JP 2984484B2 JP 4303929 A JP4303929 A JP 4303929A JP 30392992 A JP30392992 A JP 30392992A JP 2984484 B2 JP2984484 B2 JP 2984484B2
- Authority
- JP
- Japan
- Prior art keywords
- lens
- lens group
- wide
- refractive power
- object side
- 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.)
- Expired - Lifetime
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、リヤーフォーカス式の
ズームレンズに関し、特に写真用やビデオカメラ等に好
適で、画角が広く（広角端２ω≧６５°）、高変倍比
（１０倍以上）を確保しながらも、前玉径が小さく全体
としてコンパクトなリヤーフォーカス式のズームレンズ
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear focus type zoom lens, and more particularly to a rear focus type zoom lens which is suitable for a photograph or a video camera, has a wide angle of view (wide angle end 2.omega..gtoreq.65.degree.), And has a high zoom ratio (10 times). The present invention relates to a rear-focus type zoom lens that has a small front lens diameter and is compact as a whole while ensuring the above.
【０００２】[0002]
【従来の技術】最近、ホームビデオカメラ本体の小型軽
量化に伴い、撮像用ズームレンズの小型化にもめざまし
い進歩が見られ、特に全長の短縮化や前玉径の小型化、
構成の簡略化に力が注がれている。2. Description of the Related Art In recent years, as home video cameras have become smaller and lighter, remarkable progress has been made in miniaturization of imaging zoom lenses.
A great deal of effort has been put into simplifying the configuration.
【０００３】これらの目的を達成するひとつの手段とし
て、物体側の第１レンズ群以外のレンズ群を移動させて
フォーカスを行う、所謂リヤーフォーカス式のズームレ
ンズが知られている。As one means for achieving these objects, there is known a so-called rear focus type zoom lens which performs focusing by moving a lens group other than the first lens group on the object side.
【０００４】一般にリヤーフォーカス式のズームレンズ
は、第１レンズ群を移動させてフォーカスを行うズーム
レンズに比べて、第１レンズ群の有効径が小さくなり、
レンズ系全体の小型化が容易になる。又近接撮影、特に
極近接撮影が可能となり、更に比較的小型軽量のレンズ
群を移動させて行っているので、レンズ群の駆動力が小
さくてすみ迅速な焦点合わせができる特長を持ってい
る。In general, a rear focus type zoom lens has a smaller effective diameter of the first lens group than a zoom lens which performs focusing by moving the first lens group.
The size of the entire lens system can be easily reduced. In addition, close-up photography, particularly very close-up photography, is possible. Further, since the relatively small and lightweight lens group is moved, the driving force of the lens group is small, so that quick focusing can be performed.
【０００５】この様なリヤーフォーカス式のズームレン
ズとして例えば、特開昭６２−２４２１３号公報、特開
昭６３−２４７３１６号公報等では物体側より順に正の
第１レンズ群、負の第２レンズ群、正の第３レンズ群、
正の第４レンズ群を有し、第２レンズ群を移動させて変
倍を行い、第４レンズ群で変倍に伴う像面変動を補正す
ると共に、フォーカシングを行うズームレンズを開示し
ている。[0005] As such a rear focus type zoom lens, for example, Japanese Patent Application Laid-Open Nos. 62-24213 and 63-247316 disclose a positive first lens group and a negative second lens in order from the object side. Group, positive third lens group,
A zoom lens having a positive fourth lens group, performing zooming by moving the second lens group, correcting the image plane variation due to zooming with the fourth lens group, and performing focusing is disclosed. .
【０００６】特開昭５８−１６０９１３号公報では、物
体側より順に正の屈折力の第１レンズ群、負の屈折力の
第２レンズ群、正の屈折力の第３レンズ群そして正の屈
折力の第４レンズ群の４つのレンズ群を有し、第１レン
ズ群と第２レンズ群を移動させて変倍を行い、変倍に伴
う像面移動を第４レンズ群を移動させて行っている。そ
してこれらのレンズ群のうち１つ又は２つ以上のレンズ
群を移動させてフォーカスを行っている。しかし以上の
例は、変倍機能の大半を開口絞りより物体側の移動レン
ズ群で行っている為、広角端の焦点距離時に前玉と開口
絞りの間に多くのスペースを要し、全系の入射瞳位置が
深くなりやすく、前玉径は巨大にならざるを得なかっ
た。JP-A-58-160913 discloses a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, and a positive refraction in order from the object side. It has four lens groups, a fourth lens group for power, and performs zooming by moving the first lens group and the second lens group, and performs image plane movement accompanying zooming by moving the fourth lens group. ing. Then, focusing is performed by moving one or more of these lens groups. However, in the above example, most of the zooming function is performed by the moving lens group on the object side of the aperture stop, so a large amount of space is required between the front lens and the aperture stop at the focal length at the wide-angle end. The entrance pupil position of the lens was likely to be deep, and the front lens diameter had to be huge.
【０００７】一方、本出願人は、特開昭６１−２９６３
１７号公報等で、開口絞りより後方のレンズ群をズーミ
ングに際して光軸上移動可能とし、変倍機能を分担させ
ることによって、前玉と開口絞りの間の距離を短くし前
玉径の小型化を図っている。しかしこうした従来のズー
ムレンズは、ズーミング中固定の開口絞りの両側のレン
ズ群が動くため機構上複雑になりがちである。また第１
レンズ群でフォーカスを行っている為に至近距離での周
辺画角への光束を確保するため前玉径が大型化し、これ
を小型化のためにリヤーフォーカス方式に適応しようと
すると、最適な屈折力配置ではなかったり、リヤーフォ
ーカシングに伴うフォーカス収差変動が充分に補正され
ていないといった問題があった。On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 61-2963.
In Japanese Patent Publication No. 17 (1994), etc., the distance between the front lens and the aperture stop is shortened by making the lens group behind the aperture stop movable on the optical axis during zooming and sharing the variable power function, thereby reducing the diameter of the front lens. Is being planned. However, such conventional zoom lenses tend to be mechanically complex because the lens groups on both sides of the fixed aperture stop move during zooming. Also the first
Because the lens group focuses, the diameter of the front lens becomes large to secure the luminous flux to the peripheral angle of view at a close distance, and when trying to adapt it to the rear focus method for miniaturization, optimal refraction There is a problem that the arrangement is not the force arrangement or that the fluctuation of the focus aberration due to the rear focusing is not sufficiently corrected.
【０００８】一方、本出願人は特開昭５６−４８６０７
号公報（特公昭６１−４４２８８号公報）では、物体側
より順にズーミング中固定でフォーカスを行う正の屈折
力の第１レンズ群、ズーミング中変倍の為に移動する負
の屈折力の第２レンズ群、像面位置を一定にするため移
動する第３レンズ群、そして、ズーミング中固定の正の
屈折力の第４レンズ群の４つのレンズ群を有するズーム
レンズを提案している。この提案では、最も前玉径が大
きくなる広角端もしくは広角端から多少ズームした位置
でリレーレンズ前面に有る絞りを第１面方向に近づけれ
ば、前玉径の縮小に有利であるとし、実施例では絞りを
移動させている。更に、絞りと第３レンズ群が一体で動
かすことも提案している。しかしながら、第１レンズ群
でフォーカスを行っている為に至近距離での周辺画角へ
の光束を確保するため前玉径が大型化し、これを小型化
のためにリヤーフォーカス方式に適応しようとすると、
最適な屈折力配置ではなかったり、リヤーフォーカシン
グに伴うフォーカス収差変動が充分に補正されていない
といった問題があった。On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 56-48607.
In Japanese Patent Application Publication (JP-B-61-44288), a first lens unit having a positive refractive power for focusing and fixed during zooming in order from the object side, and a second lens unit having a negative refractive power moving for zooming during zooming. A zoom lens having four lens groups, a lens group, a third lens group that moves to keep the image plane position constant, and a fourth lens group having a positive refractive power fixed during zooming is proposed. According to this proposal, it is advantageous to reduce the diameter of the front lens if the stop located on the front surface of the relay lens is closer to the first surface direction at the wide-angle end where the front lens diameter is the largest or at a position slightly zoomed from the wide-angle end. In the example, the aperture is moved. Furthermore, it has been proposed that the stop and the third lens group move integrally. However, since the first lens group focuses, the diameter of the front lens becomes large in order to secure a luminous flux to the peripheral angle of view at a close distance, and if this is to be adapted to the rear focus method for miniaturization, ,
There are problems that the refractive power is not optimally arranged and that the fluctuation of the focus aberration due to the rear focusing is not sufficiently corrected.
【０００９】また同様に、特開昭５７−１１１５０７号
公報においても、ズーミング中固定でフォーカスを行う
正の屈折力の第１レンズ群、負の屈折力の第２レンズ
群、正の屈折力の第３レンズ群を有し、これら第２レン
ズ群と第３レンズ群がズーミング中反対方向に動き、第
３レンズ群には２つの正レンズ群があり、それぞれが別
々の動きをする所謂正負正正の４群構成のズームレンズ
を提案している。この提案では、アパーチャストップ
（開口絞り）を第３レンズ群内に位置決めされていると
している。しかしながらこの構成では、第２レンズ群と
第３レンズ群が逆の方向に動くため、第２・３レンズ群
の間隔を広角端で広くあける必要があり、また絞りが第
３レンズ群内にあるため広角端における入射瞳位置が最
も像面側にあることになり前玉径・全系の小型化には適
当でない。この場合も、第１レンズ群でフォーカスを行
っている為に、至近距離での周辺画角への光束を確保す
るため前玉径が大型化し、これを小型化のためにリヤー
フォーカス方式に適応しようとすると、最適な屈折力配
置ではなかったり、リヤーフォーカシングに伴うフォー
カス収差変動が充分に補正されていないといった問題が
あった。Similarly, Japanese Patent Application Laid-Open No. 57-111507 also discloses a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive lens having a positive refractive power. The zoom lens has a third lens group. The second lens group and the third lens group move in opposite directions during zooming. The third lens group includes two positive lens groups. A positive four-group zoom lens is proposed. In this proposal, an aperture stop (aperture stop) is positioned in the third lens group. However, in this configuration, since the second lens group and the third lens group move in opposite directions, it is necessary to widen the interval between the second and third lens groups at the wide-angle end, and the stop is in the third lens group. Therefore, the entrance pupil position at the wide-angle end is closest to the image plane, which is not suitable for downsizing the front lens diameter and the entire system. Also in this case, since the first lens group focuses, the diameter of the front lens becomes large to secure the luminous flux to the peripheral angle of view at a close distance, and this is adapted to the rear focus method for downsizing. If this is attempted, there is a problem that the refractive power arrangement is not optimal, and the fluctuation of the focus aberration due to the rear focusing is not sufficiently corrected.
【００１０】また、特開平３−２００１１３号公報で
も、同様な構成で、物体側から順にズーミング中固定の
正の第１レンズ群、変倍のため前後に移動する負の第２
レンズ群、第２レンズ群の動きに関連して移動する正の
第３レンズ群、変倍にともなう焦点位置の補正を一部ま
たは全部を移動させて行う正の第４レンズ群から成るズ
ームレンズを提案している。この提案によると、第２レ
ンズ群の動きに関連して移動する正の第３レンズ群の動
きとは、第４レンズ群で行う像面移動補正量を軽減させ
るために行うもので、補正機能の一部を第３レンズ群に
分担させるための動きである。具体的には、中間焦点距
離から望遠端にかけて像側から物体側に移動する事が望
ましいとしている。しかしながらこの構成では、前記公
知例と同様に、第２レンズ群と第３レンズ群が逆の方向
に動くため、第２・３レンズ群の間隔を広角側で広くあ
ける必要があり、広角端における入射瞳位置が最も像面
側にあることになり前玉径・全系の小型化には適当でな
い。In Japanese Patent Application Laid-Open No. 3-200113, a positive first lens unit fixed during zooming in order from the object side and a negative second lens unit moving back and forth for zooming are similarly constructed from the object side.
A zoom lens including a lens group, a positive third lens group that moves in association with the movement of the second lens group, and a positive fourth lens group that moves a part or all of the focal position accompanying zooming. Has been proposed. According to this proposal, the movement of the positive third lens group that moves in relation to the movement of the second lens group is performed to reduce the amount of image plane movement correction performed by the fourth lens group, and the correction function Are movements for sharing a part of the third lens group with the third lens group. Specifically, it is desirable to move from the image side to the object side from the intermediate focal length to the telephoto end. However, in this configuration, the second lens group and the third lens group move in opposite directions, as in the above-described known example, so that it is necessary to widen the interval between the second and third lens groups on the wide-angle side. The entrance pupil position is closest to the image plane, which is not suitable for downsizing the front lens diameter and the entire system.
【００１１】また、同様に特開平３−１５８８１３号公
報でも、物体側より順に正の第１レンズ群、負の第２レ
ンズ群、正の第３レンズ群、正の第４レンズ群より構成
され、第２レンズ群と第３レンズ群を光軸に沿って移動
させて変倍を行い、開口絞りを第３レンズ群と一体で移
動させるズームレンズを開示している。この提案による
と広角端から望遠端へのズーミングに伴い第２レンズ群
と第３レンズ群の間隔は減少している。また実施例にお
いても開口絞りを有する第３レンズ群が、広角端で最も
像側に位置しており、最も前玉径が大きくなる広角端も
しくは広角端から多少ズームした位置で、絞りのある第
３レンズ群近傍が最も像側付近にあり入射瞳位置が奥ま
ってしまい、前玉径の縮小に不利であり、また歪曲も大
きく前玉径の縮小化・全系の小型化を行うには適当では
ないといった欠点があった。[0011] Similarly, in Japanese Patent Application Laid-Open No. 3-15813, the lens system is composed of a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group in this order from the object side. Discloses a zoom lens in which the second lens group and the third lens group are moved along the optical axis to perform zooming, and the aperture stop is moved integrally with the third lens group. According to this proposal, the distance between the second lens group and the third lens group decreases with zooming from the wide-angle end to the telephoto end. Also in the embodiment, the third lens group having the aperture stop is located closest to the image at the wide-angle end, and at the wide-angle end where the front lens diameter is the largest or at a position slightly zoomed from the wide-angle end, the third lens group with the stop is provided. The vicinity of the three lens groups is closest to the image side, and the entrance pupil position is deep. This is disadvantageous for reducing the front lens diameter, and also has large distortion, which is suitable for reducing the front lens diameter and miniaturizing the entire system. There was a disadvantage that it was not.
【００１２】これらに対して、本出願人は、特開平３−
２１５８１０号公報において、物体側より順に、正の屈
折力の第１レンズ群、負の屈折力を有する第２レンズ
群、絞り、正の屈折力を有する第３レンズ群、そして正
の第４レンズ群を有し、広角端から望遠端への変倍に際
して第２レンズ群を像面側に移動させると共に、絞り、
第３レンズ群、第４レンズ群をいずれも物体側に凸形状
の軌跡を有するように互いに独立に移動させ、距離合わ
せに第４レンズ群を移動させリヤーフォーカス式ズーム
レンズを提案している。本提案によれば絞りと、第３レ
ンズ群の間隔をある程度確保する事が必要となり、また
第２レンズ群、絞り、第３レンズ群、第４レンズ群がそ
れぞれ互いに独立にかなり異なった移動をするので機構
上複雑になり易いという欠点があった。また、第３レン
ズ群と絞りがズーミング中別々な動きをして第３レンズ
群に対して瞳の位置が変動するので、第３レンズ群で変
動を押さえている球面収差やコマ収差、軸上色収差が、
大きく変動して適当ではない。また、本構成では、広角
化（２ω≧６０°）に対してまだまだ不十分であり、広
角化に最適なパワー配置・群移動になっていなかった。On the other hand, the present applicant has disclosed in
In the publication No. 215810, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a diaphragm, a third lens group having a positive refractive power, and a positive fourth lens The zoom lens has a lens group, and moves the second lens group toward the image plane when zooming from the wide-angle end to the telephoto end.
A rear focus zoom lens has been proposed in which the third lens group and the fourth lens group are independently moved so as to have a locus convex toward the object side, and the fourth lens group is moved in accordance with the distance. According to this proposal, it is necessary to secure a certain distance between the diaphragm and the third lens group, and the second lens group, the diaphragm, the third lens group, and the fourth lens group move significantly differently independently of each other. Therefore, there is a drawback that the mechanism tends to be complicated. Also, since the third lens group and the diaphragm move differently during zooming and the pupil position changes with respect to the third lens group, spherical aberration, coma aberration, and on-axis fluctuation which are suppressed by the third lens group. Chromatic aberration
It is not suitable because it fluctuates greatly. Further, this configuration is still insufficient for widening the angle (2ω ≧ 60 °), and the power arrangement and group movement are not optimal for widening the angle.
【００１３】[0013]
【発明が解決しようとしている課題】以上述べたよう
に、一般にズームレンズにおいて、前玉径・全系の小型
化を達成するには、第１レンズ群による距離合わせより
も、所謂リヤーフォーカス方式の方が適している。As described above, in order to reduce the front lens diameter and the overall size of a zoom lens, a so-called rear focus system is generally used rather than a distance adjustment by the first lens group. Is more suitable.
【００１４】しかしながら、従来の例えば特開昭６２−
２４２１３号公報、特開昭６３−２４７３１６号公報等
において、更に広角化を図ろうとすると、広角端寄りの
中間ズーム位置において第１レンズ群への軸外光束の入
射高が高くなり、この結果第１レンズ群のレンズ有効径
が増大してくる。第１レンズ群の有効径を小さくするた
めに第１レンズ群と絞りの間隔を短くする方法がある。
しかしながら主変倍レンズ群である第２レンズ群が、第
１レンズ群と絞りの間にあり、第１レンズ群と絞りの間
隔を縮めると第２レンズ群の変倍のための移動スペース
が不足となり、所望の変倍比、特に１０倍以上の変倍比
は確保できなくなる。第１レンズ群と絞りの間隔を縮め
た状態で、所望の変倍比を得ようとすると、第２レンズ
群の負の屈折力が強くなり、ペッツバール和が負に増大
し、像面がオーバーに倒れがちとなり不適当である。ま
た第２レンズ群のピント面に対する敏感度が大きくなり
製造精度が厳しくなり適当でなかった。[0014] However, for example, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Laid-Open Nos. 24213 and 63-247316, when an attempt is made to further increase the angle of view, the incident height of the off-axis light beam to the first lens group increases at the intermediate zoom position near the wide-angle end. The effective lens diameter of one lens group increases. In order to reduce the effective diameter of the first lens group, there is a method of shortening the distance between the first lens group and the stop.
However, the second lens group, which is the main zoom lens group, is located between the first lens group and the aperture, and if the distance between the first lens group and the aperture is reduced, the moving space for zooming the second lens group is insufficient. Therefore, a desired zoom ratio, particularly a zoom ratio of 10 or more, cannot be secured. If an attempt is made to obtain a desired zoom ratio in a state where the distance between the first lens unit and the aperture is reduced, the negative refractive power of the second lens unit becomes strong, the Petzval sum increases negatively, and the image plane becomes over. It is unsuitable because it tends to collapse. In addition, the sensitivity of the second lens group to the focal plane increases, and the manufacturing accuracy becomes severe, which is not appropriate.
【００１５】本発明の目的は、上記従来例の欠点を改善
し、特に本出願人提案の特開平３−２１５８１０号公報
の改良に関し、前玉径の小型化を行い、更に広角（２ω
＞６５°）・高変倍（１０倍以上）を確保し、機構を含
めた簡略化・小型軽量化を図りつつ、全ズーム域・全物
体距離にわたって良好な性能を有する、小型で広角化を
図った歪曲の少ないリヤーフォーカス式のズームレンズ
の提供を目的とする。An object of the present invention is to improve the drawbacks of the above-mentioned conventional example, and particularly to the improvement of Japanese Patent Application Laid-Open No. 3-215810 proposed by the present applicant.
> 65 °), high zoom ratio (10 times or more), small size and wide angle with good performance over the entire zoom range and all object distances while simplifying and reducing the size and weight including the mechanism. It is an object of the present invention to provide a rear-focus type zoom lens with little distortion.
【００１６】[0016]
【課題を解決するための手段】かかる目的のために、本
発明は、物体側から、正の屈折力の第１レンズ群、負の
屈折力の第２レンズ群、絞りを有する正の屈折力の第３
レンズ群、そして正の屈折力の第４レンズ群の順に構成
され、広角端から望遠端への変倍に際に、前記第２レン
ズ群を像面側に移動させると共に、前記第３レンズ群を
前記絞りと一体で物体側に凸状の軌跡を有するように移
動させ、前記第４レンズ群を物体側に凸状の軌跡を有す
るよう互いに独立に移動させて行い、合焦の際には前記
第４レンズ群を移動させてフォーカシングを行うズーム
レンズであって、最も物体側のレンズの外径をφ1 、広
角端の全系の焦点距離をＦｗとするとき、 ０．１４＜Ｆｗ／φ1 ＜０．２３ なる条件式を満足させたことにある。For this purpose, the present invention provides, from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a positive refractive power having a stop. The third
A lens group, and a fourth lens group having a positive refractive power. The second lens group is moved to the image plane side during zooming from the wide-angle end to the telephoto end, and the third lens group is moved. Is moved integrally with the stop so as to have a locus convex toward the object side, and the fourth lens group is moved independently so as to have a locus convex toward the object side. 0.14 <Fw / φ1 where the outer diameter of the lens closest to the object side is φ1 and the focal length of the entire system at the wide-angle end is Fw, wherein the zoom lens performs focusing by moving the fourth lens group. <0.23 has been satisfied.
【００１７】[0017]
【００１８】[0018]
【００１９】[0019]
【００２０】[0020]
【００２１】本発明は以上の条件式を満足するように構
成することにあるが、本実施例のズームレンズを設計す
る際の一つの指針を与える条件式も示しておく。The present invention is configured to satisfy the above-mentioned conditional expressions. However, conditional expressions which provide one guideline when designing the zoom lens of this embodiment are also shown.
【００２２】[0022]
【実施例】図１〜図１３は本発明に関する数値実施例の
レンズ断面図、及び諸収差図である。尚図において
（Ｂ）、（Ｃ）、（Ｄ）は各々広角端、中間ズーム位
置、望遠端における諸収差図を示す。1 to 13 are a lens sectional view and various aberration diagrams of a numerical example according to the present invention. In the figures, (B), (C), and (D) show various aberration diagrams at the wide-angle end, the intermediate zoom position, and the telephoto end, respectively.
【００２３】Ｉは正の屈折力を有する第１レンズ群、Ｉ
Ｉは負の屈折力を有する第２レンズ群、ＩＩＩは正の屈
折力を有する第３レンズ群、ＩＶは正の屈折力を有する
第４レンズ群でＳは第３レンズ群前方に固定された絞り
である。そして広角端から望遠端へのズーミングを第２
レンズ群ＩＩ、第３レンズ群そして第４レンズ群ＩＶを
矢印で示す通り移動させて行う一方、第４レンズ群ＩＶ
を移動させてフォーカシングを行っている。第１レンズ
群は常に静止している。I is a first lens group having a positive refractive power, I
I is a second lens group having a negative refractive power, III is a third lens group having a positive refractive power, IV is a fourth lens group having a positive refractive power, and S is fixed in front of the third lens group. Aperture. Zooming from the wide-angle end to the telephoto end is the second
The operation is performed by moving the lens group II, the third lens group, and the fourth lens group IV as shown by arrows, while the fourth lens group IV
Is moving to focus. The first lens group is always stationary.
【００２４】そして（１）〜（５）の各条件をそれぞれ
満足している。Each of the conditions (1) to (5) is satisfied.
【００２５】本実施例においては、まず物体側から順に
正の屈折力の第１レンズ群、負の屈折力の第２レンズ
群、絞りを有する正の屈折力の第３レンズ群、そして正
の屈折力の第４レンズ群を有し、広角端から望遠端への
変倍に際して、前記第２レンズ群を像面側に移動させる
と共に、前記第３レンズ群と絞りは、一体で物体側に凸
状の軌跡を有するように移動させ、前記第４レンズ群も
物体側に凸状の軌跡で移動させ、合焦の際には、前記第
４レンズ群を移動させてフォーカシングを行い以下の条
件を満足させている。In this embodiment, first, from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power having a stop, and a positive lens unit. A fourth lens unit having a refractive power, and moving the second lens unit toward the image plane side during zooming from the wide-angle end to the telephoto end, and the third lens unit and the diaphragm are integrally moved toward the object side. The lens is moved so as to have a convex locus, the fourth lens group is also moved along the convex locus toward the object side, and at the time of focusing, the fourth lens group is moved to perform focusing and the following conditions are satisfied. Are satisfied.
【００２６】 −０．３＜Ｍ３ｍａｘ／φ1 ＜−０．０４…（１） 但しここで、Ｍ３ｍａｘは広角端からの、第３レンズ群
と絞りの光軸上の移動量最大値であり（物体側に移動す
るのを“−”とする。）最も物体側のレンズの外径をφ
1 とする。−0.3 <M3max / φ 1 <−0.04 (1) where M3max is the maximum movement amount of the third lens unit and the stop on the optical axis from the wide-angle end ( The movement toward the object side is “-”.) The outer diameter of the lens closest to the object side is φ
Set to 1 .
【００２７】従来のズームレンズでは、第１レンズ群へ
の軸外光束の入射高は、入射瞳が第１レンズ群から深い
所（奥まったところ）にあるため、広角端寄りの中間ズ
ーム位置で最も高くなる。この入射高の最も高い位置
を、入射瞳即ち絞りを移動させることにより、広角端近
傍に設定できれば第１レンズ群の外径を最も効率的に小
さくできることになる。そのためには、第３レンズ群と
絞りは、一体で物体側に凸状の軌跡を有するように移動
させるのが、前玉径の小型化、及び機構上の簡略化にも
好ましい。In the conventional zoom lens, the incident height of the off-axis light beam to the first lens group is at an intermediate zoom position near the wide-angle end because the entrance pupil is deep (deep) from the first lens group. Will be the highest. By moving the entrance pupil, that is, the stop, to a position near the wide-angle end by moving the entrance height, the outer diameter of the first lens group can be reduced most efficiently. For this purpose, it is preferable to move the third lens group and the aperture so as to have a locus convex toward the object side as a unit, in order to reduce the diameter of the front lens and to simplify the mechanism.
【００２８】この際には、第１レンズ群はズーミング中
固定になっている方が、機構上の簡略化のためにも良
い。In this case, it is better for the first lens group to be fixed during zooming in order to simplify the mechanism.
【００２９】また、合焦の際には、前記第４レンズ群を
移動させてフォーカシングを行うこととしているが、一
般に知られている第１レンズ群を光軸上移動させて距離
合わせを行う所謂前玉フォーカス方式は、広角側で至近
距離撮影時に周辺画面に光束を確保するために前玉径が
大きくなりがちとなる。このため、このフォーカス方式
では、本発明の目的のひとつである小型化は難しくなる
ので、前述したような第４レンズ群にフォーカス機能を
持たせることが必要である。In focusing, the fourth lens group is moved to perform focusing. However, a generally known first lens group is moved on the optical axis to perform distance adjustment. The front lens focus method tends to increase the diameter of the front lens in order to secure a luminous flux on the peripheral screen at the time of shooting at a close range on the wide angle side. For this reason, in this focusing method, downsizing, which is one of the objects of the present invention, becomes difficult, and it is necessary to provide the fourth lens group with a focusing function as described above.
【００３０】特に規定している（１）式は、上述した第
１レンズ群の外径を効果的に小さくするための、具体的
な第３レンズ群と絞りの移動を述べたものである。The formula (1), which is particularly specified, specifically describes the movement of the third lens unit and the stop for effectively reducing the outer diameter of the first lens unit.
【００３１】この（１）式の上限を越えると、上述した
第１レンズ群への軸外光束の入射高の最も高い位置が、
広角端寄りの中間ズーム位置で最も高くなり前玉径を効
果的に出来ず、大型化してしまう。また下限値を越える
と、第３レンズ群の移動量が大きくなるため全長の大型
化を招き適当でない。When the value exceeds the upper limit of the expression (1), the highest position of the incident height of the off-axis light beam on the first lens unit is as follows.
At the middle zoom position near the wide-angle end, it becomes highest and the diameter of the front lens cannot be effectively increased, resulting in an increase in size. If the lower limit value is exceeded, the amount of movement of the third lens unit becomes large, which leads to an increase in the overall length, which is not appropriate.
【００３２】このように設定することにより、第１レン
ズ群の外径を最も効率的に小さくでき、この結果小型化
を図ったズームレンズが達成できる。With such a setting, the outer diameter of the first lens group can be reduced most efficiently, and as a result, a zoom lens with a reduced size can be achieved.
【００３３】ここで論じている前玉径φ1 とは、第１レ
ンズの光学有効径に準ずるもので、実際のレンズ外径の
ことである。前玉径φ1 は、第１レンズの光学有効径よ
り０〜６％程度大きいものを示す。The front lens diameter φ 1 discussed here is equivalent to the optical effective diameter of the first lens and is an actual lens outer diameter. Front lens diameter phi 1 shows those about 6% greater than the optical effective diameter of the first lens.
【００３４】また、効果的に前玉径を小さくするには、
前記絞りが第３レンズ群の最も物体側に配置されている
のが、入射瞳が第１レンズ群から最も浅いところになる
ため第１レンズ群の外径を最も効果的に小さくするのに
有効である。In order to effectively reduce the diameter of the front lens,
Since the stop is disposed closest to the object side of the third lens group, the entrance pupil is located at the shallowest position from the first lens group, so that the outer diameter of the first lens group is most effectively reduced. It is.
【００３５】また、大幅な広角化を達成するには、更に
以下の条件式を満たしているのが好ましい。In order to achieve a wide angle, it is preferable that the following conditional expression is further satisfied.
【００３６】０．１４＜Ｆｗ／φ1 ＜０．２３…（２） ここで、Ｆｗは広角端の全系の焦点距離である。0.14 <Fw / φ 1 <0.23 (2) where Fw is the focal length of the entire system at the wide-angle end.
【００３７】一般に広角端の焦点距離Ｆｗが短くなる
と、前玉径φ1 は大きくなる。逆に広角端の焦点距離Ｆ
ｗが長めになると、レンズの望遠端の明るさにもよるが
前玉径φ1 は小さくなる。第（２）式は、小型で広角の
ズームレンズを達成するための前玉径と広角端の焦点距
離の適切なバランスを提示したものである。この（１）
式の上限・下限どちらを逸脱しても小型で広角のズーム
レンズの提供はできなくなる。具体的には、上限を逸脱
すると望遠寄りのズームレンズになり、下限を逸脱する
と大型のズームレンズになりがちとなる。In general, when the focal length Fw at the wide-angle end becomes shorter, the front lens diameter φ 1 becomes larger. Conversely, the focal length F at the wide-angle end
When w is longer, depending on the brightness front lens diameter phi 1 of the telephoto end of the lens is reduced. Equation (2) presents an appropriate balance between the front lens diameter and the focal length at the wide-angle end for achieving a small, wide-angle zoom lens. This (1)
Deviating from either the upper limit or the lower limit of the formula makes it impossible to provide a small and wide-angle zoom lens. Specifically, when the value deviates from the upper limit, the zoom lens is closer to the telephoto, and when the value deviates from the lower limit, the zoom lens tends to be large.
【００３８】また、第１レンズ群への軸外光束の入射高
の最も高い位置を、広角端近傍に設定するための、第３
レンズ群と絞りの適切な移動は、全ズーム領域において
は以下の位置になっているのが好ましい。A third position for setting the highest position of the incident height of the off-axis light beam to the first lens group near the wide-angle end.
The appropriate movement of the lens group and the aperture is preferably at the following positions in the entire zoom range.
【００３９】 ０．０５＜（Ｆｍ−Ｆｗ）／（Ｆｔ−Ｆｗ）＜０．３…（３） 但し、Ｆｗ、Ｆｔは、それぞれ広角端と望遠端の全系の
焦点距離。Ｆｍは、第３レンズ群と絞りが最も物体側に
移動する位置の全系の焦点距離（Ｍ３ｍａｘを達成する
時の焦点距離）である。この（３）式の上限・下限どち
らに逸脱しても、第１レンズ群への軸外光束の入射高の
最も高い位置を広角端近傍に設定できず、第３レンズ群
と絞りの適切な移動は与えられない。即ち前玉径、全系
の大型化につながり適当ではない。0.05 <(Fm−Fw) / (Ft−Fw) <0.3 (3) where Fw and Ft are the focal lengths of the entire system at the wide-angle end and the telephoto end, respectively. Fm is the focal length (focal length when M3max is achieved) of the entire system at the position where the third lens group and the diaphragm move to the object side most. Regardless of either the upper limit or the lower limit of the equation (3), the highest position of the incident height of the off-axis light beam to the first lens group cannot be set near the wide-angle end, so that the third lens group and the stop can be appropriately adjusted. No movement is given. That is, it is not appropriate because it leads to an increase in the front lens diameter and the entire system.
【００４０】前玉径の小型化と光学全長を短くするため
には、第２レンズ群の移動と第３レンズ群の移動を適当
に選択する必要がある。In order to reduce the diameter of the front lens and shorten the overall optical length, it is necessary to appropriately select the movement of the second lens unit and the movement of the third lens unit.
【００４１】上述したＦｍの位置までは、第２レンズ群
と第３レンズ群は反対方向に動くわけであり、機構的に
相互に干渉してはいけない。また主変倍レンズ群である
第２レンズ群の移動量は、そのまま変倍比に関わるもの
であり、全長との相関を適当に取っておく必要がある。
そのためには以下の条件式を満足しているのが好まし
い。Up to the position Fm, the second lens unit and the third lens unit move in opposite directions, and must not mechanically interfere with each other. Further, the movement amount of the second lens unit, which is the main variable power lens unit, directly relates to the variable power ratio, and it is necessary to appropriately correlate the total length with the total length.
For this purpose, it is preferable that the following conditional expression is satisfied.
【００４２】 −０．４＜Ｍ３ｍａｘ／Ｍ２＜−０．０４…（４） ここでＭ２は広角端から望遠端への変倍に伴う第２レン
ズ群の移動量である。この（４）式の上限値を越える
と、第２レンズ群の移動量が大きくなり全長、前玉径が
大きくなったり、Ｍ３ｍａｘの絶対値が小さくなり第１
レンズ群への軸外光束の入射高の最も高い位置を広角端
近傍に設定できず、前玉径の大型化につながり適当でな
い。また上限値を越えると、第２レンズ群の移動量が小
さくなり所望の望遠比が確保できず、またＭ３ｍａｘの
絶対値が大きくなり全系の大型化や、２・３レンズ群の
干渉を起こしやすくなり適当でない。−0.4 <M3max / M2 <−0.04 (4) Here, M2 is the amount of movement of the second lens unit accompanying zooming from the wide-angle end to the telephoto end. When the value exceeds the upper limit of the expression (4), the moving amount of the second lens unit becomes large, the total length and the diameter of the front lens become large, and the absolute value of M3max becomes small.
The highest position of the incident height of the off-axis light beam to the lens group cannot be set near the wide angle end, which leads to an increase in the diameter of the front lens, which is not appropriate. If the value exceeds the upper limit, the amount of movement of the second lens unit becomes small, so that a desired telephoto ratio cannot be secured, and the absolute value of M3max becomes large, resulting in an increase in the size of the entire system and interference of the 2.3 lens unit. It is not suitable because it becomes easy.
【００４３】広角端の画角を広く設定するためには、広
角端において正の第１レンズ群と負の第２レンズ群の主
点間隔ｅ１が短ければ更に全系の焦点距離を短くでき広
角化が可能となる。但し第１レンズ群と第２レンズ群の
間には最低限の空気間隔が必要であり、相互にぶつかっ
ては適当でない。そのため第１レンズ群の像側主点位置
が第２レンズ群寄りに設定されているか、第２レンズ群
の物体側主点が第１レンズ群寄りに設定されているのが
好ましい。特に第１レンズ群においては前玉径の大きさ
にも絡むので以下の条件式を満たすのが好ましい。In order to set a wide angle of view at the wide-angle end, if the distance e1 between the principal points of the first positive lens unit and the second negative lens unit at the wide-angle end is short, the focal length of the entire system can be further reduced. Is possible. However, a minimum air gap is required between the first lens group and the second lens group, and it is not appropriate to collide with each other. Therefore, it is preferable that the image-side principal point of the first lens group is set closer to the second lens group, or that the object-side principal point of the second lens group is set closer to the first lens group. In particular, in the first lens group, it is preferable to satisfy the following conditional expression because the size of the front lens is also involved.
【００４４】−０．１＜Ｈ1 ′／Ｆ1 ＜０．１…（５） ここで、Ｈ1 ′は、第１レンズ群の最も像側の面の頂点
と第１レンズ群の像側主点の間隔（−は物体側、＋は像
側）で、Ｆ1 は、第１レンズ群の焦点距離を表す。この
式は、前述したように第１レンズ群と第２レンズ群の主
点間隔を短くするために必要なものである。下限値を越
えると、第１レンズ群の主点位置が物体側に行き過ぎ前
述したｅ１を短くできなくなり所望の広角にならない。
上限値を越えると、第１レンズ群と第２レンズ群の間隔
が広がり、前玉径が大きくなり適当でない。-0.1 <H 1 ′ / F 1 <0.1 (5) where H 1 ′ is the vertex of the surface closest to the image side of the first lens unit and the image side of the first lens unit. interval in the main point (- the object side, + the image side) in, F 1 represents the focal length of the first lens group. This equation is necessary to shorten the distance between the principal points of the first lens group and the second lens group as described above. If the lower limit value is exceeded, the principal point position of the first lens group goes too far to the object side, and the above-mentioned e1 cannot be shortened, and the desired wide angle cannot be obtained.
When the value exceeds the upper limit, the distance between the first lens unit and the second lens unit increases, and the diameter of the front lens becomes large, which is not appropriate.
【００４５】更に、全系を小型化にするときは、以下の
条件を満たすのが好ましい。Further, when miniaturizing the entire system, it is preferable to satisfy the following conditions.
【００４６】２．５＜Ｂｆｗ／Ｆｗ＜４．０…（６） ここで、Ｂｆｗは広角端での、物体距離無限遠時のバッ
クフォーカス（ガラスブロック、フィルター等実施例中
の“Ｇ”を除く）である。この式（６）は、全系を効果
的に小型化するのに必要な式であり、下限値を越える
と、フィルター等のブロックを入れるのが無理になるば
かりでなく、射出瞳が短めとなり、撮像素子への結像が
テレセントリック系からズレることになり不適当であ
る。また上限値を越えると大型化して不適当である。2.5 <Bfw / Fw <4.0 (6) where Bfw is the back focus at the wide-angle end when the object distance is infinity (“G” in the embodiment such as a glass block, a filter, etc.) Excluding). Equation (6) is an equation necessary for effectively reducing the size of the entire system. If the lower limit is exceeded, not only is it impossible to insert a block such as a filter, but also the exit pupil becomes shorter. However, the image formation on the image sensor is shifted from the telecentric system, which is inappropriate. On the other hand, if the ratio exceeds the upper limit, the size becomes large, which is not suitable.
【００４７】また、前玉径を小型にするには以下の式を
満たすのが好ましい。In order to reduce the diameter of the front lens, it is preferable to satisfy the following expression.
【００４８】５．７＜Ｆ1 ／Ｆｗ＜９．０…（７） この式は、第２レンズ群に対する物点、即ち倍率に係わ
る式である。全系を小さく設定するには、第２レンズ群
がズーミングに際して等倍を挟んでいるのが好ましい。
等倍を挟むと第４レンズ群のズーミングの軌跡は略往復
になり、最も効果的なスペース効率で高変倍が可能とな
る。具体的には、この（７）式の上限を越えると、第２
レンズ群に対する物点が遠くなり、第２レンズ群の結像
倍率が低くなり、効果的な小型化が難しくなる。更に、
第１レンズ群と第２レンズ群の間隔が大きくなり小型化
の達成が難しくなる。また下限値を越えると、第２レン
ズ群の倍率が大きくなり、高倍化の達成が難しくなり本
発明の目的を達成できない。5.7 <F 1 /Fw<9.0 (7) This equation relates to the object point for the second lens group, that is, the magnification. In order to set the entire system to be small, it is preferable that the second lens group has the same magnification during zooming.
When the same magnification is interposed, the locus of zooming of the fourth lens group is substantially reciprocating, and high zooming is possible with the most effective space efficiency. Specifically, if the upper limit of the equation (7) is exceeded, the second
The object point with respect to the lens group becomes far, the imaging magnification of the second lens group becomes low, and it is difficult to effectively reduce the size. Furthermore,
The distance between the first lens group and the second lens group increases, and it is difficult to achieve miniaturization. If the lower limit value is exceeded, the magnification of the second lens group becomes large, and it is difficult to achieve high magnification, and the object of the present invention cannot be achieved.
【００４９】一方、更にズーミングに伴う物体距離無限
遠時の第４レンズ群の広角端からの移動量の最大値をＭ
４ｍａｘとするとき以下の条件式を満たしているのが好
ましい。On the other hand, the maximum value of the amount of movement of the fourth lens unit from the wide-angle end when the object distance is infinity due to zooming is M
When it is set to 4max, it is preferable that the following conditional expression is satisfied.
【００５０】Ｍ４ｍａｘ／Ｍ３ｍａｘ＞１．２…（８） この式は、前玉径を小型にしつつ、全長を短くするため
の式である。主に像面移動の補正に移動する第４レンズ
群の移動に対して、絞り群である第３レンズ群の移動を
適切に選択する事により前玉径・全長の小型化を達成で
きる。（８）の下限を越えると第３レンズ群の移動量が
大きくなり前玉径・全長が大型化し適当でない。M4max / M3max> 1.2 (8) This equation is for reducing the front lens diameter and shortening the overall length. By appropriately selecting the movement of the third lens group, which is the diaphragm group, with respect to the movement of the fourth lens group mainly moving to correct the image plane movement, the front lens diameter and the overall length can be reduced. If the lower limit of (8) is exceeded, the amount of movement of the third lens unit becomes large, and the front lens diameter and overall length become large, which is not appropriate.
【００５１】またＭ３ｍａｘを達成するときの全系の焦
点距離をＦｍ、Ｍ４ｍａｘを達成するときの全系の焦点
距離をＦｎとするとき、以下の様になっているのが小型
化に適当である。When the focal length of the entire system for achieving M3max is Fm and the focal length of the entire system for achieving M4max is Fn, the following is appropriate for miniaturization. .
【００５２】Ｆｍ＜Ｆｎ…（８）′Fm <Fn (8) '
【００５３】最後に、第（５）式の所でも述べたよう
に、広角化に第１レンズ群と第２レンズ群の主点間隔ｅ
１を広角端でいかに小さくできるかは重要な点のひとつ
である。そのためには第１レンズ群の形状は具体的には
以下のような構成が好ましい。Lastly, as described in the expression (5), the principal point distance e between the first lens unit and the second lens unit is set to widen the angle.
One of the important points is how to make 1 smaller at the wide-angle end. For this purpose, the first lens group preferably has the following specific configuration.
【００５４】第１レンズ群の物体側より順に、物体側に
凸面を有する負メニスカスレンズＬ１１、空気間隔を空
けて、物体側に凸面を有する正レンズＬ１２、更に物体
側に凸面を有する正レンズＬ１３で構成され、前記Ｌ１
１、Ｌ１２で構成される空気レンズは、負の屈折力を有
することである。In order from the object side of the first lens group, a negative meniscus lens L11 having a convex surface on the object side, a positive lens L12 having a convex surface on the object side with an air gap, and a positive lens L13 having a convex surface on the object side L1
1. The air lens constituted by L12 has a negative refractive power.
【００５５】また別の構成としては、物体側から順に、
両凹レンズＬ１１、それと貼り合わされる正レンズＬ１
２、そして少なくとも１枚の正レンズを配置する構成で
も良い。As another configuration, in order from the object side,
Biconcave lens L11, positive lens L1 bonded to it
2, and at least one positive lens may be arranged.
【００５６】このような構成にする事により、第１レン
ズ群の像側主点が第２レンズ群寄りに設定され、広角端
における第１レンズ群と第２レンズ群の主点間隔ｅ１が
短く取れ広角化には有効である。With this configuration, the image-side principal point of the first lens group is set closer to the second lens group, and the principal point distance e1 between the first lens group and the second lens group at the wide-angle end is reduced. This is effective for widening the angle.
【００５７】また、第２レンズ群においても、ｅ１を広
角端で短くする為に、第２レンズ群の物体側主点を物体
側に設定するような構成にすることが、広角化には望ま
しい。Also, in the second lens group, it is desirable to set the object side principal point of the second lens group to the object side in order to shorten e1 at the wide angle end. .
【００５８】具体的には、第２レンズ群の物体側より順
に、物体側に凸面を有する負メニスカスレンズＬ２１、
両凹の負レンズＬ２１、空気間隔を挟んで正レンズＬ２
３の順に配置することである。この空気間隔によって第
２レンズ群の物体側主点が第１レンズ寄りになり、広角
側におけるｅ１を短く取りやすくなり広角化に有効であ
る。Specifically, in order from the object side of the second lens group, a negative meniscus lens L21 having a convex surface on the object side,
Biconcave negative lens L21, positive lens L2 with air spacing
3 in that order. Due to this air space, the object-side principal point of the second lens group is closer to the first lens, e1 on the wide-angle side can be easily shortened, and this is effective for widening the angle.
【００５９】以上説明したように構成することにより、
前玉径が小型で、画角が広く（２ω＞６５°）、高変倍
比を確保しつつ（１０倍以上）、機構を含めた簡略化・
小型軽量化を図った、全ズーム域・全物体距離にわたっ
て良好な性能を有する、リヤーフォーカス式のズームレ
ンズの提供が可能となる。With the configuration as described above,
The front lens diameter is small, the angle of view is wide (2ω> 65 °), and a high zoom ratio is ensured (10 times or more).
It is possible to provide a rear-focus type zoom lens that has a small size and a light weight and has good performance over the entire zoom range and all object distances.
【００６０】以下に、本発明の実施例を記載する。Hereinafter, examples of the present invention will be described.
【００６１】数値実施例において、ｒｉは物体側より順
に第ｉ番目のレンズ面の曲率半径、ｄｉは物体側より順
に第ｉ番目のレンズ厚及び空気間隔、ｎｉとνｉはそれ
ぞれ物体側より順に第ｉ番目のレンズの屈折率とアッベ
数である。In the numerical examples, ri is the radius of curvature of the i-th lens surface in the order from the object side, di is the i-th lens thickness and air gap in the order from the object side, and ni and νi are those in the order from the object side. The refractive index and Abbe number of the i-th lens.
【００６２】非球面形状は、光軸方向にＸ軸、光軸と垂
直な方向にＹ軸、光の進行方向を正とし、レンズの頂点
とＸ軸の交点を原点に採り、ｒをレンズ面の近軸曲率半
径、ｋ、Ａ2 、Ａ3 、Ａ4 、Ａ5 を非球面係数とすると
き、The aspherical shape has an X-axis in the optical axis direction, a Y-axis in a direction perpendicular to the optical axis, a positive traveling direction of light, a point of intersection between the vertex of the lens and the X-axis taken as an origin, and r as a lens surface. When the paraxial radius of curvature, k, A 2 , A 3 , A 4 , and A 5 are aspheric coefficients,
【００６３】[0063]
【外１】 なる式で表されるものである。[Outside 1] It is represented by the following formula.
【００６４】また例えば『Ｄ−０３』の表示は『１
０-3』を意味する。For example, "D-03" is displayed as "1".
0 -3 ].
【００６５】また、数値実施例におけるＧ（ｒ２３、ｒ
２４等）は、光学フィルター、フェースプレート等を示
す。In addition, G (r23, r
24) shows an optical filter, a face plate and the like.
【００６６】本実施例中では、第１レンズ群はズーミン
グ中固定である。In this embodiment, the first lens unit is fixed during zooming.
【００６７】絞りと第３レンズ群の移動量が大きめにな
ると、特にズーミングの中間領域で球面収差のズーム変
動が大きくなり、球面収差が補正過剰となりがちにな
る。これを除去するには、第３レンズ群の絞り近傍の面
に非球面を導入するのが好ましい。具体的な非球面の形
状は、例外もあるが、レンズ周辺に向うに従い、正の屈
折力が弱くなるか、負の屈折力が強くなる構成のものが
好ましい。When the amount of movement between the diaphragm and the third lens unit is relatively large, the zoom fluctuation of spherical aberration becomes large, especially in the middle area of zooming, and spherical aberration tends to be overcorrected. In order to eliminate this, it is preferable to introduce an aspherical surface on the surface of the third lens group near the stop. The specific shape of the aspheric surface is not limited, but it is preferable that the positive refractive power becomes weaker or the negative refractive power becomes stronger toward the periphery of the lens.
【００６８】第２実施例から第８実施例までは、第３レ
ンズ群に非球面を導入した例である。The second to eighth embodiments are examples in which an aspheric surface is introduced into the third lens unit.
【００６９】参考までに、各実施例の対応条件の値を第
１表に示しておくが、その中で又移動パラメータａ、
ｂ、ｃがあるが、第２レンズ群の移動量をＭ2 、第３レ
ンズ群の移動量をＭ3 とした時、このパラメータは Ｍ2 ＝ａｘ（０≦ｘ≦１） （ａ＞０） Ｍ3 ＝ｂｘ＋ｃｘ2 …（０≦ｘ≦１） （ｂ＜０） となる係数をそれぞれ示している。For reference, the values of the corresponding conditions in each embodiment are shown in Table 1, in which the movement parameters a and
Although there are b and c, when the amount of movement of the second lens group is M 2 and the amount of movement of the third lens group is M 3 , this parameter is M 2 = ax (0 ≦ x ≦ 1) (a> 0 ) M 3 = bx + cx 2 (0 ≦ x ≦ 1) (b <0).
【００７０】[0070]
【表１】 [Table 1]
【００７１】[0071]
【表２】 [Table 2]
【００７２】[0072]
【外２】 [Outside 2]
【００７３】[0073]
【外３】 [Outside 3]
【００７４】[0074]
【外４】 [Outside 4]
【００７５】[0075]
【外５】 [Outside 5]
【００７６】[0076]
【外６】 [Outside 6]
【００７７】[0077]
【外７】 [Outside 7]
【００７８】[0078]
【外８】 [Outside 8]
【００７９】[0079]
【外９】 [Outside 9]
【００８０】[0080]
【外１０】 [Outside 10]
【００８１】[0081]
【外１１】 [Outside 11]
【００８２】[0082]
【外１２】 [Outside 12]
【００８３】[0083]
【外１３】 [Outside 13]
【００８４】[0084]
【外１４】 [Outside 14]
【００８５】以上のように本発明によれば、画角が広く
（２ω≧６０°）高変倍比を確保（１０倍以上）しつ
つ、前玉径が小さく作り易く、全体として、コンパクト
なリヤーフォーカス式のズームレンズの提供が可能にな
った。As described above, according to the present invention, it is easy to make the front lens diameter small while ensuring a wide angle of view (2ω ≧ 60 °) and a high zoom ratio (10 times or more), and as a whole, a compact It is now possible to provide rear focus zoom lenses.
【図１】本発明に関する数値実施例１のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。FIG. 1 is a lens cross-sectional view and various aberration diagrams of Numerical Example 1 according to the present invention, (A) is a lens cross-sectional view, (B) is a wide-angle end,
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図２】本発明に関する数値実施例２のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。2A and 2B are a lens cross-sectional view and various aberration diagrams of Numerical Example 2 according to the present invention, FIG. 2A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図３】本発明に関する数値実施例３のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。3A and 3B are a lens cross-sectional view and various aberration diagrams of Numerical Example 3 relating to the present invention, FIG. 3A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図４】本発明に関する数値実施例４のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。4A and 4B are a lens cross-sectional view and various aberration diagrams of a numerical example 4 according to the present invention, FIG. 4A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図５】本発明に関する数値実施例５のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。5A and 5B are a lens cross-sectional view and various aberration diagrams of Numerical Example 5 relating to the present invention, FIG. 5A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図６】本発明に関する数値実施例６のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。6A and 6B are a lens cross-sectional view and various aberration diagrams of Numerical Example 6 relating to the present invention, FIG. 6A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図７】本発明に関する数値実施例７のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。7A and 7B are a lens cross-sectional view and various aberration diagrams of a numerical example 7 according to the present invention, FIG. 7A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図８】本発明に関する数値実施例８のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。FIG. 8 is a lens cross-sectional view and various aberration diagrams of Numerical Example 8 relating to the present invention, (A) is a lens cross-sectional view, (B) is a wide-angle end,
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図９】本発明に関する数値実施例９のレンズ断面図及
び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角端、
（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における諸収
差図。9A and 9B are a lens cross-sectional view and various aberration diagrams of Numerical Example 9 relating to the present invention, FIG. 9A is a lens cross-sectional view, FIG.
(C) is an intermediate zoom position, (D) is a diagram of various aberrations at the telephoto end.
【図１０】本発明に関する数値実施例１０のレンズ断面
図及び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角
端、（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における
諸収差図。10A and 10B are lens sectional views and various aberration diagrams of Numerical Example 10 relating to the present invention, FIG. 10A is a lens sectional view, FIG. 10B is a wide-angle end, FIG. 10C is an intermediate zoom position, and FIG. FIG.
【図１１】本発明に関する数値実施例１１のレンズ断面
図及び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角
端、（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における
諸収差図。11A and 11B are lens sectional views and various aberration diagrams of Numerical Example 11 relating to the present invention, FIG. 11A is a lens sectional view, FIG. 11B is a wide-angle end, FIG. 11C is an intermediate zoom position, and FIG. FIG.
【図１２】本発明に関する数値実施例１２のレンズ断面
図及び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角
端、（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における
諸収差図。12A and 12B are a lens cross-sectional view and various aberration diagrams of Numerical Example 12 relating to the present invention, FIG. 12A is a lens cross-sectional view, FIG. 12B is a wide-angle end, FIG. FIG.
【図１３】本発明に関する数値実施例１３のレンズ断面
図及び諸収差図、（Ａ）はレンズ断面図、（Ｂ）は広角
端、（Ｃ）は中間ズーム位置、（Ｄ）は望遠端における
諸収差図。13A and 13B are lens sectional views and various aberration diagrams of Numerical Example 13 relating to the present invention, FIG. 13A is a lens sectional view, FIG. 13B is a wide-angle end, FIG. 13C is an intermediate zoom position, and FIG. FIG.
Ｉ 第１レンズ群 ＩＩ 第２レンズ群 ＩＩＩ 第３レンズ群 ＩＶ 第４レンズ群 Ｓ サジタル像面 Ｍ メリディオナル像面 ｄ ｄ線 ｇ ｇ線 I First lens group II Second lens group III Third lens group IV Fourth lens group S Sagittal image plane M Meridional image plane d d-line g g-line
Claims (1)
群、負の屈折力の第２レンズ群、絞りを有する正の屈折
力の第３レンズ群、そして正の屈折力の第４レンズ群の
順に構成され、広角端から望遠端への変倍の際に、前記
第２レンズ群を像面側に移動させると共に、前記第３レ
ンズ群を前記絞りと一体で物体側に凸状の軌跡を有する
ように移動させ、前記第４レンズ群を物体側に凸状の軌
跡を有するよう互いに独立に移動させて行い、合焦の際
には前記第４レンズ群を移動させてフォーカシングを行
うズームレンズであって、最も物体側のレンズの外径を
φ1 、広角端の全系の焦点距離をＦｗとするとき、 ０．１４＜Ｆｗ／φ1 ＜０．２３ なる条件式を満足することを特徴とするリヤーフォーカ
ス式ズームレンズ。1. A first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power having a stop, and a fourth lens unit having a positive refractive power. In order to change the magnification from the wide-angle end to the telephoto end, the second lens group is moved to the image plane side, and the third lens group is formed integrally with the stop to be convex toward the object side. Are moved so as to have a locus, and the fourth lens group is moved independently so as to have a locus convex toward the object side. When focusing, the fourth lens group is moved to perform focusing. When the outer diameter of the lens closest to the object side is φ1 and the focal length of the entire system at the wide-angle end is Fw, the following conditional expression is satisfied: 0.14 <Fw / φ1 <0.23 A rear focus type zoom lens characterized by the following.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4303929A JP2984484B2 (en) | 1992-11-13 | 1992-11-13 | Rear focus zoom lens |
| US08/474,186 US5739961A (en) | 1992-04-30 | 1995-06-07 | Zoom lens |
| US08/483,850 US5784205A (en) | 1992-11-13 | 1995-06-07 | Zoom lens |
| US08/684,726 US5754346A (en) | 1992-11-13 | 1996-07-22 | Zoom lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4303929A JP2984484B2 (en) | 1992-11-13 | 1992-11-13 | Rear focus zoom lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06148520A JPH06148520A (en) | 1994-05-27 |
| JP2984484B2 true JP2984484B2 (en) | 1999-11-29 |
Family
ID=17926981
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4303929A Expired - Lifetime JP2984484B2 (en) | 1992-04-30 | 1992-11-13 | Rear focus zoom lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2984484B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6483648B1 (en) | 1999-09-10 | 2002-11-19 | Olympus Optical Co., Ltd. | Zoom lens |
| JP4156777B2 (en) | 2000-05-23 | 2008-09-24 | オリンパス株式会社 | Zoom lens |
| JP4532916B2 (en) * | 2004-01-30 | 2010-08-25 | キヤノン株式会社 | Zoom lens and imaging apparatus having the same |
| CN102998780B (en) * | 2011-09-09 | 2015-07-22 | 佳能企业股份有限公司 | Zoom lens set |
-
1992
- 1992-11-13 JP JP4303929A patent/JP2984484B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06148520A (en) | 1994-05-27 |
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