JPH09236748A - Zoom lens and rear focusing automatic focusing camera - Google Patents
Zoom lens and rear focusing automatic focusing cameraInfo
- Publication number
- JPH09236748A JPH09236748A JP8041471A JP4147196A JPH09236748A JP H09236748 A JPH09236748 A JP H09236748A JP 8041471 A JP8041471 A JP 8041471A JP 4147196 A JP4147196 A JP 4147196A JP H09236748 A JPH09236748 A JP H09236748A
- Authority
- JP
- Japan
- Prior art keywords
- lens group
- lens
- group
- image
- refractive power
- 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/143—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only
- G02B15/1431—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only the first group being positive
- G02B15/143105—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only the first group being positive arranged +-+
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Lenses (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本願発明は、ズームレンズに
関し、特にＣＣＤ等の固体撮像素子等を用いる電子スチ
ルカメラ若しくはビデオカメラに好適な２．５倍乃至４
倍の程度の変倍比を有するズーム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 zoom lens, and particularly 2.5 times to 4 times suitable for an electronic still camera or a video camera using a solid-state image sensor such as CCD.
The present invention relates to a zoom lens having a zoom ratio of about twice.
【０００２】[0002]
【従来の技術】近年、パソコンの技術的進歩や普及と共
に画像データを扱うソフトウェアの発展が著しく、パソ
コンへの画像取込みなどに用いる電子スチルカメラの要
望が高まってきている。2. Description of the Related Art In recent years, with the technical progress and popularization of personal computers, the development of software for handling image data is remarkable, and the demand for electronic still cameras used for capturing images into personal computers is increasing.
【０００３】固体撮像素子用のズームレンズとしては従
来より３群構成や４群構成のものが知られており、ビデ
オカメラ用のズームレンズでは高変倍化の傾向があり、
４群構成のものが広く用いられ、電子スチルカメラ用の
３倍前後のズームレンズでは３群構成のものもある。As a zoom lens for a solid-state image pickup device, one having a three-group structure or a four-group structure has been conventionally known, and a zoom lens for a video camera tends to have a high zoom ratio.
A 4-group structure is widely used, and there is a 3-group structure of a zoom lens of about 3 times for an electronic still camera.
【０００４】３群構成のズームレンズとしては従来より
特開昭６４−７９７１６号公報、特開平２−２９１５１
５号公報、特開平３−８９３０９号公報、特開平４−１
０６５１２号公報、特開平４−３０７５０９号公報、特
開平５−２０３８７５号公報等が知られている。As a zoom lens having a three-group structure, there are conventional zoom lenses disclosed in JP-A-64-79716 and JP-A-2-29151.
5, JP-A-3-89309, JP-A 4-1
JP06512, JP-A-4-307509, JP-A-5-203875 and the like are known.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、これら
の従来例では広角端における歪曲収差が−５％程度もあ
ったり、変倍による歪曲収差の変化が大きく、望遠端で
＋３％〜＋４％と大きかったり、或いは歪曲収差は小さ
いがレンズ全長が大きかったりした。However, in these conventional examples, the distortion aberration at the wide-angle end is about -5%, and the distortion aberration due to zooming is large, and it is large at + 3% to + 4% at the telephoto end. Or, the distortion is small but the total lens length is large.
【０００６】かかる状況に鑑み、３倍前後の変倍比を有
しながら、歪曲収差が小さく、且つレンズ全長が短いコ
ンパクトなズームレンズを提供することを本願発明の課
題とする。In view of such a situation, it is an object of the present invention to provide a compact zoom lens which has a variable magnification ratio of about 3 times, a small distortion and a short total lens length.
【０００７】また、簡単な構成でズームレンズを搭載し
た、リアフォーカス式オートフォーカスカメラを提供す
ることも本願発明の課題とする。It is another object of the present invention to provide a rear focus type autofocus camera having a zoom lens with a simple structure.
【０００８】[0008]
【課題を解決するための手段】前記課題は、物体側より
正の屈折力の第１レンズ群と、負の屈折力の第２レンズ
群と、正の屈折力の第３レンズ群とからなり、広角端か
ら望遠端への変倍に際し、前記第２レンズ群が物体側か
ら像側へ移動し、第３レンズ群が変倍時の像面補正のた
めに前後に移動するズームレンズにおいて、広角端にお
ける全系の焦点距離をｆW、前記第１レンズ群の焦点距
離をｆ1、望遠端における前記第３レンズ群の結像倍率
をｍ3Tとすると、以下の条件式を満足するズームレンズ
により達成される。The above-mentioned problems consist of a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power from the object side. In the zoom lens in which the second lens group moves from the object side to the image side during zooming from the wide-angle end to the telephoto end, and the third lens group moves back and forth for image plane correction during zooming, Let f W be the focal length of the entire system at the wide-angle end, f 1 be the focal length of the first lens unit, and m 3T be the imaging magnification of the third lens unit at the telephoto end. Achieved by the lens.
【０００９】 ０．２５＜ｆW／ｆ1＜０．５ （１） −０．３３＜ｍ3T＜−０．１ （２） 更に、広角端における前記第３レンズ群の結像倍率をｍ
3Wとすると、以下の条件式を満足するようにする。0.25 <f W / f 1 <0.5 (1) −0.33 <m 3T <−0.1 (2) Furthermore, the imaging magnification of the third lens group at the wide-angle end is m.
At 3 W , the following conditional expression should be satisfied.
【００１０】 １．２＜ｍ3W／Ｍ3T＜１．６ （３） 更に、前記第２レンズ群の焦点距離をｆ2、前記第３レ
ンズ群の焦点距離をｆ3とし、広角端における全系の焦
点距離をｆW、望遠端における全系の焦点距離をｆTとす
ると、以下の条件式を満足するようにする。1.2 <m 3W / M 3T <1.6 (3) Furthermore, the focal length of the second lens group is f 2 , the focal length of the third lens group is f 3, and the total length at the wide-angle end is When the focal length of the system is f W and the focal length of the entire system at the telephoto end is f T , the following conditional expressions are satisfied.
【００１１】 −１．２＜ｆW／ｆ2＜−０．８ （４） ０．５＜ｆW／ｆ3＜０．９ （５） ２．５＜ｆT／ｆW＜４ （６） また、物体側より順に正の屈折力の第１レンズ群と、負
の屈折力の第２レンズ群と、開口絞りと、正の屈折力の
第３レンズ群とからなり、広角端から望遠端への変倍に
際し、第２レンズ群が物体側から像側へ移動し、前記第
３レンズ群が変倍時の像面補正のため前後に移動するズ
ームレンズにおいて、前記第３レンズ群が物体側より少
なくとも１枚の正レンズを含む正の屈折力の第３−ａレ
ンズ群と、少なくとも１枚の負レンズと少なくとも１枚
の正レンズよりなる正の屈折力の第３−ｂレンズ群とか
ら構成され、前記第３−ａレンズ群と第３−ｂレンズ群
の間の空気間隔をＤabとし、広角端における全系の焦点
距離をｆWとし、前記第３−ａレンズ群と第３−ｂレン
ズ群の焦点距離をそれぞれｆ3a、ｆ3bとすると、以下の
条件式を満足するようにする。−1.2 <f W / f 2 <−0.8 (4) 0.5 <f W / f 3 <0.9 (5) 2.5 <f T / f W <4 (6 ) Further, the first lens group having a positive refractive power, the second lens group having a negative refractive power, the aperture stop, and the third lens group having a positive refractive power are arranged in this order from the object side. In zoom lens in which the second lens group moves from the object side to the image side during zooming to the edge and the third lens group moves back and forth for image plane correction during zooming, the third lens group is The third-a lens group having a positive refractive power including at least one positive lens from the object side, and the third-b lens group having a positive refractive power including at least one negative lens and at least one positive lens And the air distance between the 3-a lens group and the 3-b lens group is D ab, and the focal length of the entire system at the wide-angle end is Is defined as f W, and the focal lengths of the third-a lens group and the third-b lens group are f 3a and f 3b , respectively, the following conditional expressions are satisfied.
【００１２】 ０．６＜Ｄab／ｆW＜１．２ （７） ０．８５＜ｆ3a／ｆ3b＜１．２ （８） 更に、前記第３−ａレンズ群が両凸単レンズであり、前
記第３−ｂレンズ群が両凸の単レンズと負のメニスカス
レンズとの接合レンズから構成する。0.6 <D ab / f W <1.2 (7) 0.85 <f 3a / f 3b <1.2 (8) Further, the third-a lens group is a biconvex single lens. The third-b lens group is composed of a cemented lens composed of a biconvex single lens and a negative meniscus lens.
【００１３】更に好ましくは第３−ｂレンズ群に含まれ
る負レンズのアッベ数をν3bとすると以下の条件式を満
足するようにする。More preferably, if the Abbe number of the negative lens included in the 3-b lens group is ν 3b , the following conditional expression is satisfied.
【００１４】 ν3b＜３０ （９） また、物体側より順に正の屈折力の第１レンズ群と、負
の屈折力の第２レンズ群と、正の屈折力の第３レンズ群
とからなる撮影レンズと、前記撮影レンズによる像を光
電的に変換する撮像素子と、前記第３レンズ群を前後に
移動させる駆動装置とを備え、広角端から望遠端への変
倍に際しては前記第２レンズ群を単調に物体側から像側
へ移動させ、被写体への合焦に際し、被写体情報を基に
前記第３レンズを前後に移動させるリアフォーカス式オ
ートフォーカスカメラとする。Ν 3b <30 (9) Further, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the third lens group having a positive refractive power are arranged in this order from the object side. A photographic lens, an image sensor for photoelectrically converting an image formed by the photographic lens, and a drive device for moving the third lens group back and forth, and the second lens when zooming from the wide-angle end to the telephoto end. A rear focus type autofocus camera in which the group is monotonically moved from the object side to the image side and the third lens is moved back and forth based on the subject information when focusing on the subject.
【００１５】また、前記リアフォーカス式オートフォー
カスカメラにおいて、前記撮像素子の画面の一部からの
電気信号により、被写体像の所定の空間周波数のコント
ラストを演算する演算装置を備え、被写体への合焦に際
し、前記被写体像のコントラストの演算結果が高くなる
ように前記駆動装置により前記第３レンズ群を駆動させ
る。Further, in the rear-focus type autofocus camera, an arithmetic device for calculating a contrast of a subject image at a predetermined spatial frequency by an electric signal from a part of a screen of the image pickup device is provided, and the subject is focused. At this time, the drive unit drives the third lens group so that the calculation result of the contrast of the subject image becomes high.
【００１６】更に、前記第３レンズ群の望遠端での結像
倍率をｍ3Tとすると以下の条件式を満足するようにす
る。Further, if the image forming magnification at the telephoto end of the third lens unit is m 3T , the following conditional expression is satisfied.
【００１７】 −０．５＜ｍ3T＜０ （１０） 以上の構成において、条件式（１）の下限を下回ると広
角端における負の歪曲収差が大きくなり、上限を越える
と第１レンズの焦点距離が短くなり過ぎ、変倍のための
第２レンズ群の屈折力も大きくなり、変倍による収差変
動が大きくなり補正が困難である。特に望遠端では正の
歪曲収差が発生し、好ましくない。また、広角端で開口
効率が小さくなり、周辺光量比が小さくなる。-0.5 <m 3T <0 (10) In the above configuration, when the lower limit of the conditional expression (1) is exceeded, the negative distortion aberration at the wide-angle end becomes large, and when the upper limit is exceeded, the focus of the first lens is increased. The distance becomes too short, the refracting power of the second lens unit for zooming becomes large, and the aberration variation due to zooming becomes large, which makes correction difficult. In particular, positive distortion occurs at the telephoto end, which is not preferable. Further, the aperture efficiency is reduced at the wide-angle end, and the peripheral light amount ratio is reduced.
【００１８】条件式（２）の下限を下回ると望遠端で正
の歪曲収差が発生し易くなり、第３レンズ群でフォーカ
シングする場合はフォーカシングに必要な移動量が大き
くなり、レンズ全長が長くなったり、フォーカシングに
よる収差変動が大きくなり好ましくない。逆に条件式
（２）の上限を越えるとバックフォーカスが短くなり、
ローパスフィルターや赤外カットフィルターなどに必要
なスペースが確保できなくなる。If the lower limit of conditional expression (2) is not reached, positive distortion tends to occur at the telephoto end, and when focusing with the third lens group, the amount of movement required for focusing becomes large and the total lens length becomes long. Or, the aberration variation due to focusing becomes large, which is not preferable. On the contrary, when the upper limit of conditional expression (2) is exceeded, the back focus becomes short,
The space required for low pass filters and infrared cut filters cannot be secured.
【００１９】条件式（３）の下限を下回ると変倍による
歪曲収差の変動が大きくなり、望遠端で正の歪曲収差が
発生し、上限を越えると同じ変倍比を得るための第２群
の変倍に対する負担が大きくなり、コマ収差や像面湾曲
の変動が大きくなる。If the lower limit of conditional expression (3) is not reached, the variation of distortion due to zooming will become large, and positive distortion will occur at the telephoto end, and if it exceeds the upper limit, the second lens group for obtaining the same zoom ratio. And the coma aberration and the curvature of field vary greatly.
【００２０】条件式（４）の下限を下回ると変倍による
収差変動の補正が難しくなり、上限を越えるとペッツバ
ール和が大きくなり、像面湾曲が大きくなって、好まし
くない。If the lower limit of conditional expression (4) is not reached, it will be difficult to correct aberration fluctuations due to zooming, and if it exceeds the upper limit, Petzval sum will be large and field curvature will be large, which is not preferable.
【００２１】条件式（５）の下限を下回ると、第３レン
ズ群でフォーカシングする場合の移動量が大きくなった
り、レンズ全長が大きくなり、上限を越えると広角端で
負の歪曲収差が大きくなり、好ましくない。If the lower limit of conditional expression (5) is not reached, the amount of movement for focusing by the third lens unit will be large, or the total lens length will be large. If the upper limit is exceeded, negative distortion will be large at the wide-angle end. , Not preferable.
【００２２】条件式（６）の下限を下回ると変倍比が不
足し、上限を越えると収差変動、特に歪曲収差の変動が
大きく、全変倍域で歪曲収差の良好なズームレンズを得
難くなる。If the lower limit of conditional expression (6) is exceeded, the zoom ratio will be insufficient, and if it exceeds the upper limit, aberration fluctuations, especially fluctuations in distortion will be large, making it difficult to obtain a zoom lens with good distortion in the entire zoom range. Become.
【００２３】また、前記負の屈折力の第２レンズ群と正
の屈折力の第３レンズ群の間に開口絞りを配置すると
き、前記第３レンズ群を物体側より少なくとも１枚の正
レンズを含む正の屈折力の第３−ａレンズ群と、少なく
とも１枚の負レンズと１枚の正レンズよりなり正の屈折
力の第３−ｂレンズ群とで構成し、条件式（７）及び
（８）を満足するように第３−ａレンズ群と第３−ｂレ
ンズ群の屈折力及び空気間隔を設定すると、歪曲収差及
び像面湾曲を良好に補正することができる。When arranging an aperture stop between the second lens unit having the negative refractive power and the third lens unit having the positive refractive power, the third lens unit is provided with at least one positive lens from the object side. A third lens group having a positive refracting power and a third lens group having a positive refracting power, which is composed of at least one negative lens and one positive lens, and has a conditional expression (7). By setting the refracting powers and the air gaps of the 3-a lens group and the 3-b lens group so as to satisfy (8) and (8), it is possible to excellently correct distortion and field curvature.
【００２４】条件式（７）の下限を下回るとペッツバー
ル和は小さくなり、像面湾曲は良くなるが、広角端での
負の歪曲収差が大きくなり好ましくない。また、上限を
越えると歪曲収差は小さくなるが、第３レンズ群の屈折
力を保つため、第３−ａレンズ群及び第３−ｂレンズ群
における個々の屈折力が大きくなり、ペッツバール和が
大きくなってしまい、像面湾曲が大きくなる。If the lower limit of conditional expression (7) is not reached, Petzval sum will be small and field curvature will be good, but negative distortion at the wide-angle end will be large, which is not preferable. Further, when the upper limit is exceeded, distortion becomes small, but since the refractive power of the third lens group is maintained, the individual refractive powers of the third-a lens group and the third-b lens group become large, and the Petzval sum becomes large. And the curvature of field becomes large.
【００２５】条件式（８）の上限及び下限を越えると第
３−ａレンズ群と第３−ｂレンズ群の屈折力配分に偏り
が生じ、やはりペッツバール和が大きくなったり、コマ
収差が発生し易くなり、好ましくない。If the upper limit and the lower limit of conditional expression (8) are exceeded, the refractive power distribution of the 3-a lens group and the 3-b lens group will be biased, and the Petzval sum will also become large and coma will occur. It becomes easy and not preferable.
【００２６】更に、第３−ｂレンズ群に負レンズが含ま
れるようにすると、広角端で負の歪曲収差を補正し易く
なり、また条件式（９）を満足するようにすると、色収
差、特に倍率色収差を良好に補正できる。Further, if the third-b lens unit includes a negative lens, it becomes easy to correct negative distortion at the wide-angle end, and if conditional expression (9) is satisfied, chromatic aberration, especially It is possible to excellently correct lateral chromatic aberration.
【００２７】また、前記３群構成のズームレンズとそれ
による被写体の像を光電的に変換する撮像素子とを有
し、撮像素子の画面の一部からの電気信号より被写体像
の所定の空間周波数のコントラストを演算する演算装置
と、前記ズームレンズの第３レンズ群を前後に移動させ
る駆動装置とを備え、広角端から望遠端への変倍に際し
ては、前記ズームレンズの第２レンズ群を物体側から像
側、即ち撮影素子側へ単調に移動させるようにし、被写
体への合焦に際しては、前記被写体のコントラストの演
算結果が高くなるように前記駆動装置にて前記第３レン
ズ群を移動させるようにすると、ズームレンズ特有のカ
ム或いはズームポジションの検出用のセンサー、及び被
写体の測距装置等が不要になり、カメラが簡単且つコン
パクトになる。また、カメラを構成する部品点数も減少
し、組み立て易く、故障の少ないカメラとなる。Further, the zoom lens having the three-group structure and an image pickup device for photoelectrically converting an image of the subject by the zoom lens are provided, and a predetermined spatial frequency of the subject image is obtained from an electric signal from a part of the screen of the image pickup device. Of the zoom lens and a driving device for moving the third lens group of the zoom lens back and forth. When zooming from the wide-angle end to the telephoto end, the second lens group of the zoom lens is used as an object. Side to the image side, that is, the imaging device side, is monotonically moved, and when focusing on a subject, the third lens group is moved by the drive device so that the calculation result of the contrast of the subject becomes high. This eliminates the need for a cam unique to the zoom lens or a sensor for detecting the zoom position, a distance measuring device for the object, and the like, and the camera is simple and compact. In addition, the number of parts constituting the camera is reduced, and the camera is easy to assemble and has few failures.
【００２８】条件式（１０）の下限を下回ると合焦のた
めの第３レンズ群の移動量が大きくなり、機械的ストロ
ークを確保しづらくなる。逆に上限を越えると、バック
フォーカスが短くなり、撮像素子とレンズとの間のロー
パスフィルターや赤外カットフィルター等のためのスペ
ースの確保が困難になる。If the lower limit of conditional expression (10) is exceeded, the amount of movement of the third lens group for focusing becomes large, and it becomes difficult to secure a mechanical stroke. On the other hand, when the value exceeds the upper limit, the back focus becomes short, and it becomes difficult to secure a space for a low-pass filter or an infrared cut filter between the image pickup element and the lens.
【００２９】[0029]
【実施例】以下に本願発明のズームレンズ及びリアフォ
ーカス式オートフォーカスカメラの実施例を示す。EXAMPLES Examples of the zoom lens and the rear focus type autofocus camera of the present invention will be shown below.
【００３０】各実施例における記号は以下の通りであ
る。Symbols in each embodiment are as follows.
【００３１】ｆ：全系の焦点距離 ＦNO：Ｆナンバー ω：半画角 Ｒ：屈折面の曲率半径 Ｄ：屈折面の間隔 Ｎd：レンズ材料の屈折率 νd：レンズ材料のアッベ数 ｆW：広角端における全系の焦点距離 ｆT：望遠端における全系の焦点距離 ｆ1：第１レンズ群の焦点距離 ｆ2：第２レンズ群の焦点距離 ｆ3：第３レンズ群の焦点距離 ｆ3a：第３−ａレンズ群の焦点距離 ｆ3b：第３−ｂレンズ群の焦点距離 Ｄab：第３−ａレンズ群と第３−ｂレンズ群の空気間隔 ｍ3W：広角端における第３レンズ群の結像倍率 ｍ3T：望遠端における第３レンズ群の結像倍率 ν3b：第３−ｂレンズ群のアッベ数 １Ｇ：第１レンズ群 ２Ｇ：第２レンズ群 ３Ｇ：第３レンズ群 ３−ａＧ：第３−ａレンズ群 ３−ｂＧ：第３−ｂレンズ群 〔実施例１〕 ｆ＝ ６．９６〜１１．８６〜１９．８０ ＦNO＝２．９ 〜 ２．８６〜 ２．６４ ω＝２５．９°〜１５．４°〜 ９．３° 以下にレンズデータを示す。F: focal length of the entire system F NO : F number ω: half angle of view R: radius of curvature of refracting surface D: distance between refracting surfaces N d : refractive index of lens material ν d : Abbe number of lens material f W: the focal length of the entire system at the wide-angle end f T: the focal point of the entire system at the telephoto end distance f 1: the focal length of the first lens group distance f 2: the focal point of the second lens group distances f 3: the focal point of the third lens group distance f 3a: at the wide angle end: the 3a lens group having a focal length f 3b: the focal length of the 3b lens group D ab: No. 3a lens group and the air gap of the 3b lens group m 3W Imaging magnification of the third lens group m 3T : Imaging magnification of the third lens group at the telephoto end ν 3b : Abbe number of the 3-b lens group 1G: 1st lens group 2G: 2nd lens group 3G: 3rd Lens Group 3-aG: Third-a Lens Group 3-bG: Third-b Lens Group [Example 1] f = .96~11.86~19.80 F NO = 2.9 ~ 2.86~ 2.64 ω = 25.9 ° ~15.4 ° ~ 9.3 ° shows lens data below.
【００３２】[0032]
【表１】 [Table 1]
【００３３】次に、条件式（１）〜（９）に相当する値
を示す。Next, the values corresponding to the conditional expressions (1) to (9) are shown.
【００３４】ｆW ／ｆ1 ＝ ０．３１ ｍ3T ＝−０．２８ ｍ3W／ｍ3T＝ １．４５ ｆW ／ｆ2 ＝−０．９１ ｆW ／ｆ3 ＝ ０．６５ ｆT ／ｆW ＝ ２．８４ Ｄab／ｆW ＝ ０．９７ ｆ3a／ｆ3b＝ １．０３ ν3b ＝２３．８ なお、本実施例のレンズ断面図と変倍のための移動態様
を図１に示し、広角端（Ａ）、中間（Ｂ）、望遠端
（Ｃ）での収差図を図２に示す。F W / f 1 = 0.31 m 3T = -0.28 m 3W / m 3T = 1.45 f W / f 2 = -0.91 f W / f 3 = 0.65 f T / f W = 2.84 D ab / f W = 0.97 f 3a / f 3b = 1.03 ν 3b = 23.8 It is to be noted that the lens sectional view of this embodiment and a movement mode for zooming are shown in FIG. 2 shows aberration diagrams at the wide-angle end (A), the middle (B), and the telephoto end (C).
【００３５】〔実施例２〕 ｆ＝ ６．９８〜１１．８６〜１９．８０ ＦNO＝２．９ 〜 ２．８６〜 ２．６４ ω＝２６．０°〜１５．６°〜 ９．４° 以下にレンズデータを示す。Example 2 f = 6.98 to 11.86 to 19.80 F NO = 2.9 to 2.86 to 2.64 ω = 26.0 ° to 15.6 ° to 9.4 ° The lens data is shown below.
【００３６】[0036]
【表２】 [Table 2]
【００３７】次に、条件式（１）乃至条件式（９）に相
当する値を示す。Next, the values corresponding to the conditional expressions (1) to (9) are shown.
【００３８】ｆW ／ｆ1 ＝ ０．３５ ｍ3T ＝−０．２８ ｍ3W／ｍ3T＝ １．５４ ｆW ／ｆ2 ＝−０．９９ ｆW ／ｆ3 ＝ ０．６３ ｆT ／ｆW ＝ ２．８４ Ｄab／ｆW ＝ １．０６ ｆ3a／ｆ3b＝ １．０２ ν3b ＝２３．８ なお、本実施例のレンズ断面図を図３に示し、広角端
（Ａ）、中間（Ｂ）、望遠端（Ｃ）での収差図を図４に
示す。F W / f 1 = 0.35 m 3T = -0.28 m 3W / m 3T = 1.54 f W / f 2 = -0.99 f W / f 3 = 0.63 f T / f W = 2.84 D ab / f W = 1.06 f 3a / f 3b = 1.02 ν 3b = 23.8 It is to be noted that the lens cross-sectional view of this embodiment is shown in FIG. 3 at the wide angle end (A). Aberration diagrams at the middle, intermediate (B) and telephoto end (C) are shown in FIG.
【００３９】〔実施例３〕 ｆ＝ ６．９８〜１１．８６〜１９．８０ ＦNO＝２．９ 〜 ２．８４〜 ２．６３ ω＝２６．０°〜１５．６°〜 ９．４° 以下にレンズデータを示す。Example 3 f = 6.98 to 11.86 to 19.80 F NO = 2.9 to 2.84 to 2.63 ω = 26.0 ° to 15.6 ° to 9.4 ° The lens data is shown below.
【００４０】[0040]
【表３】 [Table 3]
【００４１】次に、条件式（１）乃至条件式（９）に相
当する値を示す。Next, the values corresponding to the conditional expressions (1) to (9) are shown.
【００４２】ｆW ／ｆ1 ＝ ０．３４ ｍ3T ＝−０．２６ ｍ3W／ｍ3T＝ １．５９ ｆW ／ｆ2 ＝−０．９６ ｆW ／ｆ3 ＝ ０．６６ ｆT ／ｆW ＝ ２．８４ Ｄab／ｆW ＝ ０．９１ ｆ3a／ｆ3b＝ １．０２ ν3b ＝２３．８ なお、本実施例のレンズ断面図を図５に示し、広角端
（Ａ）、中間（Ｂ）、望遠端（Ｃ）での収差図を図６に
示す。F W / f 1 = 0.34 m 3T = -0.26 m 3W / m 3T = 1.59 f W / f 2 = -0.96 f W / f 3 = 0.66 f T / f W = 2.84 D ab / f W = 0.91 f 3a / f 3b = 1.02 ν 3b = 23.8 A lens cross-sectional view of this example is shown in FIG. 5 at the wide-angle end (A). Aberration diagrams at the intermediate, intermediate (B), and telephoto ends (C) are shown in FIG.
【００４３】〔実施例４〕 ｆ＝ ６．９８〜１１．８６〜１９．８１ ＦNO＝２．９ 〜 ２．８６〜 ２．６４ ω＝２６．１°〜１５．５°〜 ９．４° 以下にレンズデータを示す。Example 4 f = 6.98 to 11.86 to 19.81 F NO = 2.9 to 2.86 to 2.64 ω = 26.1 ° to 15.5 ° to 9.4 ° The lens data is shown below.
【００４４】[0044]
【表４】 [Table 4]
【００４５】次に、条件式（１）乃至条件式（９）に相
当する値を示す。Next, the values corresponding to the conditional expressions (1) to (9) are shown.
【００４６】ｆW ／ｆ1 ＝ ０．３４ ｍ3T ＝−０．２６１ ｍ3W／ｍ3T＝ １．５９ ｆW ／ｆ2 ＝−０．９４ ｆW ／ｆ3 ＝ ０．６５ ｆT ／ｆW ＝ ２．８４ Ｄab／ｆW ＝ ０．９２ ｆ3a／ｆ3b＝ １．００ ν3b ＝２３．８ なお、本実施例のレンズ断面図を図７に示し、広角端
（Ａ）、中間（Ｂ）、望遠端（Ｃ）での収差図を図８に
示す。F W / f 1 = 0.34 m 3T = -0.261 m 3W / m 3T = 1.59 f W / f 2 = -0.94 f W / f 3 = 0.65 f T / f W = 2.84 D ab / f W = 0.92 f 3a / f 3b = 1.00 ν 3b = 23.8 A lens cross-sectional view of this example is shown in FIG. 7 and at the wide angle end (A). FIG. 8 shows aberration diagrams at the intermediate, intermediate (B), and telephoto ends (C).
【００４７】〔実施例５〕 ｆ＝ ６．９７〜１１．８６〜１９．８０ ＦNO＝２．９ 〜 ２．９０〜 ２．６６ ω＝２６．０°〜１５．５°〜 ９．３° 以下にレンズデータを示す。Example 5 f = 6.97 to 11.86 to 19.80 F NO = 2.9 to 2.90 to 2.66 ω = 26.0 ° to 15.5 ° to 9.3 ° The lens data is shown below.
【００４８】[0048]
【表５】 [Table 5]
【００４９】次に、条件式（１）乃至条件式（９）に相
当する値を示す。Next, the values corresponding to the conditional expressions (1) to (9) are shown.
【００５０】ｆW ／ｆ1 ＝ ０．３４ ｍ3T ＝−０．３０ ｍ3W／ｍ3T＝ １．４８ ｆW ／ｆ2 ＝−１．０１ ｆW ／ｆ3 ＝ ０．６７ ｆT ／ｆW ＝ ２．８４ なお、本実施例のレンズ断面図を図９に示し、広角端
（Ａ）、中間（Ｂ）、望遠端（Ｃ）での収差図を図１０
に示す。F W / f 1 = 0.34 m 3T = -0.30 m 3W / m 3T = 1.48 f W / f 2 = -1.01 f W / f 3 = 0.67 f T / f W = 2.84 A lens cross-sectional view of this example is shown in FIG. 9, and aberration diagrams at the wide-angle end (A), intermediate (B), and telephoto end (C) are shown in FIG.
Shown in
【００５１】次に、本願発明のリアフォーカス式オート
フォーカスカメラの概念図を図１１に示す。Next, FIG. 11 shows a conceptual diagram of the rear focus type autofocus camera of the present invention.
【００５２】同図において、物体側より正の屈折力の第
１レンズ群１Ｇと、負の屈折力の第２レンズ群２Ｇと、
開口絞りＫと、正の屈折力の第３レンズ群３Ｇと、赤外
カットフィルタ及びローパスフィルタＣと、撮影レンズ
による像を光電的に変換するＣＣＤ等の撮像素子Ｈが配
設されている。撮像素子Ｈの受光面Ｈ1 における一部Ｈ
2 から電気信号を演算装置Ｉに入力し、演算装置Ｉにて
被写体像の所定の空間周波数のコントラストを演算す
る。そして、被写体像のコントラストの演算結果が高く
なるように、駆動装置Ｊは第３レンズ群３Ｇを前後に移
動させ、撮影レンズを被写体に合焦させる。In the figure, the first lens group 1G having a positive refractive power and the second lens group 2G having a negative refractive power from the object side,
An aperture stop K, a third lens group 3G having a positive refractive power, an infrared cut filter and a low pass filter C, and an image pickup device H such as a CCD for photoelectrically converting an image formed by the taking lens are provided. Part H of the light receiving surface H 1 of the image sensor H
The electric signal from 2 is input to the arithmetic unit I, and the arithmetic unit I calculates the contrast of the subject image at a predetermined spatial frequency. Then, the driving device J moves the third lens group 3G back and forth to focus the photographing lens on the subject so that the calculation result of the contrast of the subject image becomes high.
【００５３】なお、広角端から望遠端への変倍に際して
は第２レンズ群２Ｇを単調に物体側から像側へ移動させ
る。When zooming from the wide-angle end to the telephoto end, the second lens group 2G is monotonically moved from the object side to the image side.
【００５４】[0054]
【発明の効果】請求項１〜５のズームレンズによれば、
広角端での歪曲収差が−３％程度であり、望遠端での歪
曲収差も＋１％以下と、歪曲収差が良好に補正された３
倍程度の変倍比を有するズームレンズを得ることができ
る。また、収差図に示す如く、像面湾曲や球面収差等の
諸収差も良好に補正されている。According to the zoom lens of claims 1 to 5,
The distortion at the wide-angle end was about -3%, and the distortion at the telephoto end was + 1% or less.
It is possible to obtain a zoom lens having a variable power ratio of about double. Further, as shown in the aberration diagram, various aberrations such as field curvature and spherical aberration are well corrected.
【００５５】請求項６〜８のリアフォーカス式オートフ
ォーカスカメラによれば、変倍は第２レンズ群を前後に
移動させるだけであるため、カムが不要であり、撮像素
子で受けた被写体像のコントラストを高めるように第３
レンズ群を移動させてフォーカシングするため、ズーム
ポジションを検出するセンサーや被写体距離を検出する
ための測距装置も不要となる。従って、カメラの構造が
単純になり、また部品点数も削減でき、組み立て易く、
故障の少ないカメラを得ることができる。According to the rear focus type autofocus camera of the sixth to eighth aspects, since the zooming only moves the second lens group back and forth, no cam is required, and the object image received by the image sensor is Third to increase the contrast
Since the lens group is moved for focusing, a sensor for detecting a zoom position and a distance measuring device for detecting a subject distance are not required. Therefore, the structure of the camera is simple, the number of parts can be reduced, and it is easy to assemble,
It is possible to obtain a camera with few failures.
【図１】実施例１のレンズ断面図と変倍のための移動態
様の図である。FIG. 1 is a lens cross-sectional view of Example 1 and a diagram of a movement mode for zooming.
【図２】実施例１の広角端（Ａ）、中間（Ｂ）、望遠端
（Ｃ）での収差図である。FIG. 2 is an aberration diagram at a wide-angle end (A), a middle (B), and a telephoto end (C) according to the first exemplary embodiment.
【図３】実施例２のレンズ断面図である。FIG. 3 is a sectional view of a lens according to a second embodiment.
【図４】実施例２の広角端（Ａ）、中間（Ｂ）、望遠端
（Ｃ）での収差図である。FIG. 4 is an aberration diagram at a wide-angle end (A), a middle (B), and a telephoto end (C) according to a second exemplary embodiment.
【図５】実施例３のレンズ断面図である。FIG. 5 is a sectional view of a lens according to a third embodiment.
【図６】実施例３の広角端（Ａ）、中間（Ｂ）、望遠端
（Ｃ）での収差図である。FIG. 6 is an aberration diagram at a wide-angle end (A), a middle (B), and a telephoto end (C) according to a third exemplary embodiment.
【図７】実施例４のレンズ断面図である。FIG. 7 is a lens cross-sectional view of Example 4.
【図８】実施例４の広角端（Ａ）、中間（Ｂ）、望遠端
（Ｃ）での収差図である。FIG. 8 is an aberration diagram at a wide-angle end (A), a middle (B), and a telephoto end (C) according to a fourth exemplary embodiment.
【図９】実施例５のレンズ断面図である。FIG. 9 is a lens cross-sectional view of Example 5.
【図１０】実施例５の広角端（Ａ）、中間（Ｂ）、望遠
端（Ｃ）での収差図である。FIG. 10 is an aberration diagram of Example 5 at the wide-angle end (A), the middle (B), and the telephoto end (C).
【図１１】リアフォーカス式オートフォーカスカメラの
概念図である。FIG. 11 is a conceptual diagram of a rear focus type autofocus camera.
１Ｇ 第１レンズ群 ２Ｇ 第２レンズ群 ３Ｇ 第３レンズ群 ３−ａＧ 第３−ａレンズ群 ３−ｂＧ 第３−ｂレンズ群 Ｈ 撮像素子 Ｉ 演算装置 Ｊ 駆動装置 1G 1st lens group 2G 2nd lens group 3G 3rd lens group 3-aG 3-a lens group 3-bG 3-b lens group H Image sensor I Computing device J Driving device
Claims (8)
と、負の屈折力の第２レンズ群と、正の屈折力の第３レ
ンズ群とからなり、広角端から望遠端への変倍に際し、
前記第２レンズ群が物体側から像側へ移動し、前記第３
レンズ群が変倍時の像面補正のために前後に移動するズ
ームレンズにおいて、 広角端における全系の焦点距離をｆW、前記第１レンズ
群の焦点距離をｆ1、望遠端における前記第３レンズ群
の結像倍率をｍ3Tとすると、以下の条件式を満足するこ
とを特徴とするズームレンズ。 ０．２５＜ｆW／ｆ1＜０．５ −０．３３＜ｍ3T＜−０．１1. A first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power from the object side. When changing the magnification,
The second lens group moves from the object side to the image side,
In a zoom lens in which the lens unit moves back and forth for image plane correction during zooming, the focal length of the entire system at the wide-angle end is f W , the focal length of the first lens unit is f 1 , and the focal length at the telephoto end is A zoom lens characterized by satisfying the following conditional expression, where the image forming magnification of the three lens groups is m 3T . 0.25 <f W / f 1 < 0.5 -0.33 <m 3T <-0.1
倍率をｍ3Wとすると、以下の条件式を満足することを特
徴とする請求項１に記載のズームレンズ。 １．２＜ｍ3W／ｍ3T＜１．６2. The zoom lens according to claim 1, wherein the following conditional expression is satisfied, where m 3W is the imaging magnification of the third lens group at the wide-angle end. 1.2 <m 3W / m 3T <1.6
記第３レンズ群の焦点距離をｆ3とし、広角端における
全系の焦点距離をｆW、望遠端における全系の焦点距離
をｆTとすると、以下の条件式を満足することを特徴と
する請求項２に記載のズームレンズ。 −１．２＜ｆW／ｆ2＜−０．８ ０．５＜ｆW／ｆ3＜０．９ ２．５＜ｆT／ｆW＜４3. The focal length of the second lens group is f 2 , the focal length of the third lens group is f 3 , the focal length of the entire system at the wide-angle end is f W , and the focal length of the entire system at the telephoto end. The zoom lens according to claim 2, wherein the following conditional expression is satisfied, where f T is f T. -1.2 <f W / f 2 <-0.8 0.5 <f W / f 3 <0.9 2.5 <f T / f W <4
群と、負の屈折力の第２レンズ群と、開口絞りと、正の
屈折力の第３レンズ群とからなり、広角端から望遠端へ
の変倍に際し、前記第２レンズ群が物体側から像側へ移
動し、前記第３レンズ群が変倍時の像面補正のため前後
に移動するズームレンズにおいて、 前記第３レンズ群が物体側より少なくとも１枚の正レン
ズを含む正の屈折力の第３−ａレンズ群と、少なくとも
１枚の負レンズと少なくとも１枚の正レンズよりなる正
の屈折力の第３−ｂレンズ群とから構成され、前記第３
−ａレンズ群と前記第３−ｂレンズ群の間の空気間隔を
Ｄabとし、広角端における全系の焦点距離をｆWとし、
前記第３−ａレンズ群と前記第３−ｂレンズ群の焦点距
離をそれぞれｆ3a、ｆ3bとすると、以下の条件式を満足
することを特徴とするズームレンズ。 ０．６＜Ｄab／ｆW＜１．２ ０．８５＜ｆ3a／ｆ3b＜１．２4. A first lens group having a positive refracting power, a second lens group having a negative refracting power, an aperture stop, and a third lens group having a positive refracting power in order from the object side. In the zoom lens, the second lens group moves from the object side to the image side during zooming from the zoom lens to the telephoto end, and the third lens group moves back and forth for image plane correction during zooming. A third lens group having a positive refracting power, which includes at least one positive lens from the object side, and a third lens group having a positive refracting power, which includes at least one negative lens and at least one positive lens. and a third lens group b,
The air distance between the -a lens group and the 3-b lens group is D ab , the focal length of the entire system at the wide-angle end is f W ,
A zoom lens characterized by satisfying the following conditional expressions, where f 3a and f 3b are the focal lengths of the third-a lens group and the third-b lens group, respectively. 0.6 <D ab / f W <1.2 0.85 <f 3a / f 3b <1.2
あり、前記第３−ｂレンズ群が両凸の単レンズと負のメ
ニスカスレンズとの接合レンズからなることを特徴とす
る請求項４に記載のズームレンズ。5. The third-a lens group is a biconvex single lens, and the third-b lens group is a cemented lens of a biconvex single lens and a negative meniscus lens. Item 4. The zoom lens according to Item 4.
と、負の屈折力の第２レンズ群と、正の屈折力の第３レ
ンズ群とからなる撮影レンズと、前記撮影レンズによる
像を光電的に変換する撮像素子と、前記第３レンズ群を
前後に移動させる駆動装置とを備え、広角端から望遠端
への変倍に際しては前記第２レンズ群を単調に物体側か
ら像側へ移動させ、被写体への合焦に際し、被写体情報
を基に前記第３レンズ群を前後に移動させることを特徴
とするリアフォーカス式オートフォーカスカメラ。6. A photographing lens comprising a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power from the object side; An image pickup device for photoelectrically converting an image and a driving device for moving the third lens group back and forth are provided, and when the magnification is changed from the wide-angle end to the telephoto end, the second lens group is monotonically imaged from the object side. A rear focus type autofocus camera which is moved to the side and moves the third lens group back and forth based on subject information when focusing on the subject.
号により、被写体像の所定の空間周波数のコントラスト
を演算する演算装置を備え、被写体への合焦に際し、前
記被写体像のコントラストの演算結果が高くなるように
前記駆動装置により前記第３レンズ群を駆動させること
を特徴とする請求項６に記載のリアフォーカス式オート
フォーカスカメラ。7. A calculation device for calculating a contrast of a subject image at a predetermined spatial frequency based on an electric signal from a part of a screen of the image sensor, and calculating a contrast of the subject image when focusing on the subject. 7. The rear focus type autofocus camera according to claim 6, wherein the third lens group is driven by the driving device so that the result is high.
をｍ3Tとすると、以下の条件式を満足することを特徴と
する請求項６又は請求項７に記載のリアフォーカス式オ
ートフォーカスカメラ。 −０．５＜ｍ3T＜０8. The rear focus type auto according to claim 6, wherein the following conditional expression is satisfied, where m 3T is the imaging magnification of the third lens group at the telephoto end. Focus camera. -0.5 <m 3T <0
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8041471A JPH09236748A (en) | 1996-02-28 | 1996-02-28 | Zoom lens and rear focusing automatic focusing camera |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8041471A JPH09236748A (en) | 1996-02-28 | 1996-02-28 | Zoom lens and rear focusing automatic focusing camera |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH09236748A true JPH09236748A (en) | 1997-09-09 |
Family
ID=12609287
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8041471A Pending JPH09236748A (en) | 1996-02-28 | 1996-02-28 | Zoom lens and rear focusing automatic focusing camera |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH09236748A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114815197A (en) * | 2022-06-29 | 2022-07-29 | 江西晶超光学有限公司 | Optical system, lens module and electronic equipment |
-
1996
- 1996-02-28 JP JP8041471A patent/JPH09236748A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114815197A (en) * | 2022-06-29 | 2022-07-29 | 江西晶超光学有限公司 | Optical system, lens module and electronic equipment |
| CN114815197B (en) * | 2022-06-29 | 2022-10-21 | 江西晶超光学有限公司 | Optical system, lens module and electronic equipment |
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