JP3667054B2 - Rear focus zoom lens and camera having the same - Google Patents

Rear focus zoom lens and camera having the same Download PDF

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Publication number
JP3667054B2
JP3667054B2 JP27976597A JP27976597A JP3667054B2 JP 3667054 B2 JP3667054 B2 JP 3667054B2 JP 27976597 A JP27976597 A JP 27976597A JP 27976597 A JP27976597 A JP 27976597A JP 3667054 B2 JP3667054 B2 JP 3667054B2
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Prior art keywords
lens
convex
positive
refractive power
facing
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JPH11101941A (en
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博之 浜野
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キヤノン株式会社
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B15/00Optical objectives with means for varying the magnification
    • G02B15/14Optical 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
    • G02B15/144Optical 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 four groups only
    • G02B15/1441Optical 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 four groups only the first group being positive
    • G02B15/144113Optical 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 four groups only the first group being positive arranged +-++
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B15/00Optical objectives with means for varying the magnification
    • G02B15/14Optical 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
    • G02B15/145Optical 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 five groups only
    • G02B15/1451Optical 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 five groups only the first group being positive
    • G02B15/145121Optical 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 five groups only the first group being positive arranged +-+-+
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B27/00Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/64Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
    • G02B27/646Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for small deviations, e.g. due to vibration or shake

Description

【0001】
【発明の属する技術分野】
本発明はリヤーフォーカス式のズームレンズ及びそれを有するカメラに関し、特に写真用カメラやビデオカメラ、そして放送用カメラ等に用いられる広角端の撮影画角が75度以上と広画角でかつ変倍比4〜20、Fナンバー1.6〜1.8程度の大口径比で高変倍比のリヤーフォーカス式のズームレンズ及びそれを有するカメラに関するものである。
【0002】
【従来の技術】
最近、ホームビデオカメラ等の小型軽量化に伴い、撮像用のズームレンズの小型化にも目覚ましい進歩が見られ、特にレンズ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。
【0003】
これらの目的を達成する1つの手段として、物体側の第1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。
【0004】
一般にリヤーフォーカス式のズームレンズは第1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り、又、近接撮影、特に極近接撮影が容易となり、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等の特長がある。
【0005】
このよう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、特開平6-34882 号公報や、特開昭64-68709号公報では、物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、そして正の屈折力の第4群の4つのレンズ群を有し、第2群を移動させて変倍を行い、第4群を移動させて変倍に伴う像面変動とフォーカスを行っている。
【0006】
又、特開平6-317747号公報では、物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、そして正の屈折力の第4群の4つのレンズ群を有し、第2群を移動させて変倍を行い、第4群を移動させて変倍に伴う像面変動とフォーカスを行うと共に変倍時に第3群の前方に設けた開口絞りを移動させている。
【0007】
又、特開平4-301612号公報では物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、正の屈折力の第4群、そして負の屈折力の第5群の5つのレンズ群を有し、該第2群を像面側へ移動させて広角端から望遠端への変倍を行い、変倍に伴う像面変動を該第4群を移動させて補正すると共に、該第4群を移動させてフォーカスを行っている。
【0008】
【発明が解決しようとする課題】
一般にズームレンズにおいて、リヤーフォーカス方式を採用すると前述の如くレンズ系全体が小型化され、又、迅速なるフォーカスが可能となり、更に近接撮影が容易となる等の特長が得られる。
【0009】
しかしながら反面、広画角化を図ろうとすると、第1群の有効径が周辺光束の確保の為に増大し、又、第1群と第2群の主点間隔が広くなり、第1群の有効径が増大する傾向があった。
【0010】
この他、レンズ全長の更なる短縮化を図る為に各レンズ群の屈折力を強めるとフォーカスの際の収差変動が大きくなり、無限遠物体から近距離物体に至る物体距離全般にわたりレンズ系全体の小型化を図りつつ、高い光学性能を得るのが大変難しくなるという問題点が生じてくる。
【0011】
特に広画角で高変倍のズームレンズでは全変倍範囲にわたり、又、物体距離全般にわたり高い光学性能を得るのが大変難しくなるという問題点が生じてくる。
【0012】
本発明はリヤーフォーカス方式を採用しつつ、広画角化及び高変倍化を図る際、レンズ系全体の大型化を防止しつつ、広角端から望遠端に至る全変倍範囲にわたり、又、無限遠物体から近距離物体に至る物体距離全般にわたり、良好なる光学性能を有したリヤーフォーカス式のズームレンズ及びそれを有するカメラの提供を目的とする。
【0013】
【課題を解決するための手段】
請求項1の発明のリヤフォーカス式のズームレンズは、物体側より順に正の屈折力の第1群、変倍用の負の屈折力の第2群、正の屈折力の第3群、そして合焦用のレンズ群を有するリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
−5<H12W/fW<0 ・・・・・(1)
0.75<|f11/f1|<2.0・・・・・(2)
なる条件を満足することを特徴としている。
請求項2の発明は、請求項1の発明において前記第11群は両レンズ面が凹面の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。
請求項3の発明は、請求項1の発明において前記第11群は物体側に凸面を向けたメニスカス状の負レンズを有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。請求項4の発明は、請求項1の発明において前記第11群は物体側に凸面を向けたメニスカス状の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。
【0014】
請求項5の発明のリヤフォーカス式のズームレンズは物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、そして正の屈折力の第4群の4つのレンズ群を有し、該第2群を像面側へ移動させて広角端から望遠端への変倍を行い、変倍に伴う像面変動を該第4群を移動させて補正すると共に該第4群を移動させてフォーカスを行うリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
−5<H12W/fW<0 ・・・・・(1)
0.75<|f11/f1|<2.0・・・・(2)
なる条件を満足することを特徴としている。
請求項6の発明のフォーカス式のズームレンズは、物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、負の屈折力の第4群、そして正の屈折力の第5群の5つのレンズ群を有し、該第2群を像面側へ移動させて広角端から望遠端への変倍を行い、変倍に伴う像面変動を該第4群を移動させて補正すると共に該第4群を移動させてフォーカスを行うリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
−5<H12W/fW<0 ・・・・・(1)
0.75<|f11/f1|<2.0・・・・・(2)
なる条件を満足することを特徴としている。
【0015】
請求項7の発明は、請求項5又は6の発明において前記第11群は両レンズ面が凹面の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。
請求項8の発明は、請求項5又は6の発明において前記第11群は物体側に凸面を向けたメニスカス状の負レンズを有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。
請求項9の発明は、請求項5又は6の発明において前記第11群は物体側に凸面を向けたメニスカス状の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴としている。
請求項10の発明のカメラは請求項1乃至9のいずれか1項のリヤーフォーカス式のズームレンズを有していることを特徴としている。
【0016】
【発明の実施の形態】
図1、図5、図9は本発明のリヤーフォーカス式のズームレンズの数値実施例1、2、3のレンズ断面図、図2〜図4は本発明の後述する数値実施例1の広角端、中間、望遠端の諸収差図である。図6〜図8は本発明の後述する数値実施例2の広角端、中間、望遠端の諸収差図である。図10〜図12は本発明の後述する数値実施例3の広角端、中間、望遠端の諸収差図である。
【0017】
まず、図1の実施形態1について説明する。
【0018】
図中L1は正の屈折力の第1群、L2は負の屈折力の第2群、L3は正の屈折力の第3群、L4は正の屈折力の第4群である。SPは開口絞りであり、第3群L3の中に配置している。Gは色分離系やフェースプレートやフィルター等のガラスブロックである。IPは像面である。第1群L1は負の屈折力の第11群L11と正の屈折力の第12群L12とを有している。
【0019】
本実施形態では広角端から望遠端への変倍に際して、矢印のように第2群を像面側へ移動させると共に、変倍に伴う像面変動を第4群を物体側に凸状の軌跡を有しつつ移動させて補正している。
【0020】
又、第4群を光軸上移動させて、フォーカスを行うリヤーフォーカス式を採用している。同図に示す第4群の実線の曲線4aと点線の曲線4bは各々無限遠物体と近距離物体にフォーカスしているときの広角端から望遠端への変倍に伴う際の像面変動を補正する為の移動軌跡を示している。尚、第1群と第3群は変倍及びフォーカスの際固定である。
【0021】
本実施形態においては第4群を移動させて変倍に伴う像面変動の補正を行うと共に第4群を移動させてフォーカスを行うようにしている。特に同図の曲線4a、4bに示すように広角端から望遠端への変倍に際して物体側へ凸状の軌跡を有するように移動させている。これにより第3群と第4群との空間の有効利用を図りレンズ全長の短縮化を効果的に達成している。
【0022】
本実施形態では、前述の如く全系の広角端の焦点距離fW、広角端における第1群と第2群の主点間隔H12Wが条件式(1)を満足するようにしており、これによって、諸収差を良好に補正しつつ、レンズ全長の短縮化を図っている。
【0023】
条件式(1)の下限値を越えて、第1群と第2群の主点間隔H12Wを小さくしようとすると、広角端からズーム中間にかけての非点収差や倍率色収差の補正が困難になる。逆に上限値を越えて主点間隔が大きくなると前玉径(第1群の有効径)を十分に小さくすることが難しくなってくる。
【0024】
次に本実施形態のこの他の特徴について説明する。
【0025】
(A1)第1群L1を負の屈折力の第11群L11と正の屈折力の第12群L12で構成している。この様に第1群L1をいわゆるレトロフォーカスタイプのレンズ構成とすることで第1群の後側主点から第1群の後側面までの距離を短くし、第1群と第2群の主点間隔を小さくしてもメカ的に干渉しないようにしている。
【0026】
そして、第11群L11と第1群L1の焦点距離を各々f11、f1としたとき、
0.75<|f11/f1|<2.0……(2)
なる条件式を満足するようにして、諸収差を良好に補正している。
【0027】
条件式(2)の下限値を越えて、第11群の負の屈折力を大きくしようとすると、主点間隔を小さくするには有利だが、広角端からズーム中間での非点収差や倍率色収差の補正が困難になる。逆に上限値を越えて第11群の負の屈折力が小さくなると、第1群と第2群の主点間隔が十分に小さくならず、レンズ系全体の小型化が難しくなってくる。
【0028】
(A2)前記第11群は両レンズ面が凹面の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることである。
【0029】
これにより第1群全体を十分にレトロフォーカス型にして、第1群と第2群主点間隔を小さくして、収差補正を良好に行いつつ、レンズ系全体の小型化を図っている。
【0030】
(A3)本実施形態では光学系のバックフォーカスを必要十分なだけ確保するために、第3群を物体側に凸面を向けたメニスカス状の負レンズと正レンズとを有するレトロフォーカスタイプのレンズ構成としている。
【0031】
(A4)第4群を3枚の正レンズと1枚の負レンズで構成し、フォーカシングに伴う収差変動が小さくなるようにしている。尚、第4群に非球面を用いても良く、これによればレンズ枚数を削減することができる。
【0032】
(A5)第2群の焦点距離をf2、広角端と望遠端における全系の焦点距離を各々fW、fTとするとき、
【0033】
【数1】
を満足するようにしている。
【0034】
条件式(3)は第2群の負の屈折力に関するものであり、変倍に伴う収差変動を少なくしつつ所定の変倍比を効果的に得るためのものである。条件式(3)の下限値を越えて第2群の屈折力が強くなり過ぎるとレンズ系全体の小型化は容易となるが、ペッツバール和が負の方向に増大し像面湾曲が大きくなると共に、変倍に伴う収差変動が大きくなる。又、上限値を越えて第2群の屈折力が弱くなり過ぎると変倍に伴う収差変動は少なくなるが、所定の変倍比を得るための第2群の移動量が増大し、絞りと前玉との距離が長くなって前玉径が増大するので良くない。
【0035】
(A6)本実施形態ではレンズ枚数を削減するために各レンズ群、特に第3群、第4群に非球面を導入するのが良い。
【0036】
次に、図5の実施形態2について説明する。
【0037】
図中、L1は正の屈折力の第1群、L2は負の屈折力の第2群、L3は正の屈折力の第3群、L4は負の屈折力の第4群、L5は正の屈折力の第5群である。SPは開口絞りであり、第2群L2と第3群L3との間に配置している。Gはガラスブロック、IPは像面である。
【0038】
広角端から望遠端への変倍に際して矢印のように第2群を像面側へ移動させると共に、変倍に伴う像面変動を第4群を像面側に凸状の軌跡を有しつつ移動させて補正している。又、負の屈折力の第4群を光軸上移動させてフォーカスを行うリヤーフォーカス式を採用している。
【0039】
同図に示す第4群の実線の曲線4aと点線の曲線4bは各々無限遠物体と近距離物体にフォーカスしているときの広角端から望遠端への変倍に伴う際の像面変動を補正する為の移動軌跡を示している。尚、第1群、第3群、第5群は変倍及びフォーカスの際固定である。
【0040】
本実施例においては第4群を移動させて変倍に伴う像面変動の補正を行うと共に第4群を移動させてフォーカスを行うようにしている。特に同図の曲線4a、4bに示すように広角端から望遠端への変倍に際して物体側へ凸状の軌跡を有する用に移動させている。これにより第4群と第5群との空間の有効利用を図りレンズ全長の短縮化を効果的に達成している。
【0041】
本実施形態において、例えば望遠端において無限遠物体から近距離物体へフォーカスを行う場合は、同図の直線4cに示すように第4群を後方へ繰り込むことにより行っている。
【0042】
以上のように本実施形態では負の屈折力の第4群で変倍に伴う像面変動の補正を行うことにより、広角端付近での変倍時の焦点距離の変化を大きくして広画角化に伴う前玉径の増大を効果的に抑制している。
【0043】
尚、本実施形態において変倍に伴う球面収差や軸上色収差を良好に補正するには、第4群は少なくとも1枚の正レンズを含むようなレンズ構成にするのが良い。
【0044】
次に本実施形態のこの他の特徴について説明する。
【0045】
(B1)本実施形態も実施形態1と同様に前述の条件式(1)及び構成(A1)、(A4)の条件式(2)、(3)を満足するようにしている。
【0046】
(B2)前記第11群は物体側に凸面を向けたメニスカス状の負レンズを有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることである。
【0047】
これによって、収差補正を良好に行いつつ、広画角化を図る際の前玉径(第1群)の有効径の増大を防止している。
【0048】
(B3)第1群を全体として3枚の正レンズと2枚の負レンズで構成している。レンズ構成枚数をこれ以上少なくしようとすると倍率色収差の変動を抑えるのが困難になったり、望遠端における球面収差やコマ収差の補正が困難になる。
【0049】
(B4)広画角化を図るときに発生しやすい広角端での負の歪曲収差を補正するために、第1群に非球面を用いる。特に非球面は第12群に用いるのが良く、その形状はレンズ周辺でレンズ中心より正の屈折力が強くなるような形状が望ましい。
【0050】
次に図9の実施形態3について説明する。
【0051】
本実施形態は図1の実施形態1に比べて、第11群L11と第12群L12との間に可変頂角プリズムVPを設けている点が異なっており、その他の基本構成は同じである。
【0052】
本実施形態では、光学系全体が振動したときの画像ブレを傾角検出センサー(不図示)からの信号に基づいて可変頂角プリズムVPのプリズム頂角をアクチュエータ(不図示)によって変化させて補正している。
【0053】
可変頂角プリズムVPを光学系の物体側に配置すると、光学系の画角が広くなると可変頂角プリズムの径が増大してしまう。
【0054】
そこで、本実施形態では可変頂角プリズムVPを第11群L11と第12群L12の間の空間を利用して配置することにより、空間を効果的に活用し、レンズ全長の増加を抑えると共に可変頂角プリズムの径を小さくしている。
【0055】
又、可変頂角プリズムVPの物体側に負の屈折力の第11群L11を配置することで、防振に必要な可変頂角プリズムの駆動角を小さくしている。
【0056】
尚、可変頂角プリズムVPは片面を縦、横両方向に駆動させても、両面をそれぞれ縦、横方向に駆動させても良い。
【0057】
又、可変頂角プリズムの代わりに、それと同様の機能を有するような2枚の凹凸レンズを駆動して防振を行っても良い。
【0058】
次に本実施形態のこの他の特徴について説明する。
【0059】
(C1)本実施形態も実施形態1と同様に条件式(1)〜(3)を満足するようにしている。
【0060】
(C2)前記第11群は物体側に凸面を向けたメニスカス状の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることである。
【0061】
これによって広画角化及びレンズ系全体の小型化を図っている。
【0062】
次に本発明の数値実施例を示す。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は物体側より第i番目のレンズ厚及び空気間隔、Niとνiは物体側より第i番目のレンズのガラスの屈折率とアッベ数である。又、数値実施例1におけるR33〜R39、数値実施例2におけるR31、R32、数値実施例3におけるR32、R33は光学フィルター、フェースプレートなどを示すが、これらは必要に応じて省略し得る。
【0063】
非球面形状は光軸方向にX軸、光軸と垂直方向にH軸、光の進行方向を正とし、Rを近軸曲率半径、B、C、D、Eを各々非球面係数としたとき、
【0064】
【数2】
なる式で表している。又、「e−X」は「10-X」を意味している。
【0065】
又、前述の各条件式と数値実施例における諸数値との関係を表−1に示す。
【0066】
【外1】
【0067】
【外2】
【0068】
【外3】
【0069】
【表1】
【0070】
【発明の効果】
本発明によれば以上のように各要素を設定することにより、リヤーフォーカス方式を採用しつつ、広画角化及び高変倍化を図る際、レンズ系全体の大型化を防止しつつ、広角端から望遠端に至る全変倍範囲にわたり、又、無限遠物体から近距離物体に至る物体距離全般にわたり、良好なる光学性能を有したリヤーフォーカス式のズームレンズ及びそれを有するカメラを達成することができる。
【図面の簡単な説明】
【図1】 本発明の数値実施例1のレンズ断面図
【図2】 本発明の数値実施例1の広角端の収差図
【図3】 本発明の数値実施例1の中間の収差図
【図4】 本発明の数値実施例1の望遠端の収差図
【図5】 本発明の数値実施例2のレンズ断面図
【図6】 本発明の数値実施例2の広角端の収差図
【図7】 本発明の数値実施例2の中間の収差図
【図8】 本発明の数値実施例2の望遠端の収差図
【図9】 本発明の数値実施例3のレンズ断面図
【図10】 本発明の数値実施例3の広角端の収差図
【図11】 本発明の数値実施例3の中間の収差図
【図12】 本発明の数値実施例3の望遠端の収差図
【符号の説明】
L1 第1群
L11 第11群
L12 第12群
L2 第2群
L3 第3群
L4 第4群
L5 第5群
SP 絞り
d d線
g g線
ΔS サジタル像面
ΔM メリディオナル像面
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rear focus type zoom lens and a camera having the same, and in particular, a wide angle of view with a wide angle of view of 75 ° or more used for a photographic camera, a video camera, a broadcast camera, etc., and a variable magnification. The present invention relates to a rear focus type zoom lens having a large aperture ratio of about 4 to 20 and an F number of about 1.6 to 1.8 and a high zoom ratio, and a camera having the same.
[0002]
[Prior art]
Recently, with the reduction in size and weight of home video cameras and the like, remarkable progress has been made in reducing the size of zoom lenses for imaging, particularly in reducing the overall length of the lens, reducing the front lens diameter, and simplifying the configuration. It has been poured.
[0003]
As one means for achieving these objects, a so-called rear focus type zoom lens that performs focusing by moving a lens group other than the first group on the object side is known.
[0004]
In general, a rear focus type zoom lens has a smaller effective diameter of the first lens unit than a zoom lens that focuses by moving the first lens unit, making it easy to downsize the entire lens system. The close proximity photography is easy, and the relatively small and light lens group is moved, so that the driving force of the lens group is small and quick focusing is possible.
[0005]
As such a rear focus type zoom lens, for example, in JP-A-62-24213, JP-A-6-34882, and JP-A-64-68709, a positive refractive power is sequentially applied from the object side. There are four lens groups, the first group, the second group having a negative refractive power, the third group having a positive refractive power, and the fourth group having a positive refractive power. Then, the fourth lens group is moved to focus and change the image plane accompanying zooming.
[0006]
Japanese Patent Laid-Open No. 6-317747 discloses a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power in order from the object side. It has four lens groups, and the second group is moved to perform zooming, and the fourth group is moved to perform image plane variation and focusing accompanying zooming, and in front of the third group at the time of zooming The aperture stop provided is moved.
[0007]
In Japanese Patent Laid-Open No. 4-301612, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, a fourth group having a positive refractive power, Then, it has five lens units of the fifth group having negative refractive power, and the second group is moved to the image plane side to perform zooming from the wide-angle end to the telephoto end. The fourth group is moved for correction, and the fourth group is moved for focusing.
[0008]
[Problems to be solved by the invention]
In general, when a rear focus method is used in a zoom lens, the entire lens system can be miniaturized as described above, quick focusing can be performed, and close-up photography can be facilitated.
[0009]
On the other hand, however, when an attempt is made to widen the angle of view, the effective diameter of the first group increases in order to secure the peripheral light flux, and the distance between the principal points of the first group and the second group becomes wider. There was a tendency for the effective diameter to increase.
[0010]
In addition, if the refractive power of each lens group is increased in order to further shorten the overall lens length, aberration fluctuations at the time of focusing increase, and the entire lens system over the entire object distance from an object at infinity to a near object. There is a problem that it is very difficult to obtain high optical performance while downsizing.
[0011]
In particular, a zoom lens having a wide angle of view and a high zoom ratio has a problem that it is very difficult to obtain high optical performance over the entire zoom range and over the entire object distance.
[0012]
The present invention adopts a rear focus method, and when widening the angle of view and high zooming is achieved, while preventing the enlargement of the entire lens system, over the entire zooming range from the wide-angle end to the telephoto end, An object of the present invention is to provide a rear focus type zoom lens having a good optical performance over an entire object distance from an infinitely distant object to a close object and a camera having the same.
[0013]
[Means for Solving the Problems]
The rear focus type zoom lens according to the first aspect of the present invention includes, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power for zooming, a third group having a positive refractive power, and In a rear focus type zoom lens having a focusing lens group, the first group has two lens groups of an eleventh group having a negative refractive power and a twelfth group having a positive refractive power. When the focal length at the wide angle end is fW, the principal point interval between the first group and the second group at the wide angle end is H12W, and the focal lengths of the eleventh group and the first group are f11 and f1, respectively .
-5 <H12W / fW <0 (1)
0.75 <| f11 / f1 | <2.0 (2)
It is characterized by satisfying the following conditions.
According to a second aspect of the present invention, in the first aspect of the invention, the eleventh group has two negative lenses whose concave surfaces are concave, and the twelfth group is a positive lens whose convex surfaces are convex, and a convex surface on the object side. A negative lens having a meniscus shape facing the lens, a positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
According to a third aspect of the present invention, in the first aspect of the invention, the eleventh group has a meniscus negative lens having a convex surface facing the object side, and the twelfth group has a positive lens whose both lens surfaces are convex, the object side It is characterized by having a meniscus negative lens with a convex surface facing to the positive lens, a positive lens with a convex surface facing the object side, and a positive lens whose both lens surfaces are convex surfaces. According to a fourth aspect of the present invention, in the first aspect of the invention, the eleventh group has two meniscus negative lenses having a convex surface facing the object side, and the twelfth group has a positive lens having convex surfaces on both lenses, A meniscus negative lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
[0014]
The zoom lens of the rear focus type according to the invention of claim 5 comprises, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a positive refractive power. There are four lens groups in the fourth group, and the second group is moved to the image plane side to perform zooming from the wide-angle end to the telephoto end, and the image plane variation accompanying zooming is moved in the fourth group. In the rear focus type zoom lens that corrects the fourth group and moves the fourth group to perform focusing, the first group includes two lenses of an eleventh group having a negative refractive power and a twelfth group having a positive refractive power. has a group, the focal length at the wide angle end of the entire system fW, H12W the main point interval of the first group and the second group at the wide-angle end, respectively the focal length of said subgroup and the first group f11, f1 When
-5 <H12W / fW <0 (1)
0.75 <| f11 / f1 | <2.0 (2)
It is characterized by satisfying the following conditions.
According to a sixth aspect of the present invention, there is provided a focus type zoom lens in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a first group having a negative refractive power. There are four lens groups and five lens groups of a fifth group having positive refractive power, and the second group is moved to the image plane side to perform zooming from the wide-angle end to the telephoto end. In a rear focus type zoom lens which corrects a surface variation by moving the fourth group and performs focusing by moving the fourth group, the first group has an eleventh group having a negative refractive power and a positive refraction. The lens has two lens groups of the twelfth group of forces, the focal length at the wide angle end of the entire system is fW, the distance between the principal points of the first group and the second group at the wide angle end is H12W, the eleventh group and the first group When the focal lengths of the groups are f11 and f1, respectively.
-5 <H12W / fW <0 (1)
0.75 <| f11 / f1 | <2.0 (2)
It is characterized by satisfying the following conditions.
[0015]
According to a seventh aspect of the invention, in the fifth or sixth aspect of the invention, the eleventh group has two negative lenses whose concave lens surfaces are concave, and the twelfth group is a positive lens whose convex lens surfaces are both convex. It is characterized by having a meniscus negative lens with a convex surface facing to the positive lens, a positive lens with a convex surface facing the object side, and a positive lens whose both lens surfaces are convex surfaces.
According to an eighth aspect of the present invention, in the fifth or sixth aspect, the eleventh group has a meniscus negative lens having a convex surface facing the object side, and the twelfth group has a positive lens having convex surfaces on both lenses. A meniscus negative lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
According to a ninth aspect of the present invention, in the fifth or sixth aspect, the eleventh group has two meniscus negative lenses having a convex surface facing the object side, and the twelfth group has a positive surface in which both lens surfaces are convex. The lens is characterized by having a negative meniscus lens having a convex surface facing the object side, a positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
According to a tenth aspect of the present invention, there is provided a camera having the rear focus zoom lens according to any one of the first to ninth aspects.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
1, 5, and 9 are sectional views of numerical examples 1, 2, and 3 of the rear focus type zoom lens according to the present invention, and FIGS. 2 to 4 are wide-angle ends of numerical example 1 according to the present invention to be described later. FIG. 6 is a diagram showing various aberrations at the intermediate and telephoto ends. FIGS. 6 to 8 are graphs showing various aberrations at the wide-angle end, the intermediate end, and the telephoto end according to Numerical Example 2 described later. 10 to 12 are graphs showing various aberrations at the wide-angle end, the intermediate end, and the telephoto end according to Numerical Example 3 to be described later.
[0017]
First, Embodiment 1 of FIG. 1 is demonstrated.
[0018]
In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and L4 is a fourth group having a positive refractive power. SP is an aperture stop, which is disposed in the third lens unit L3. G is a glass block such as a color separation system, a face plate or a filter. IP is the image plane. The first group L1 includes an eleventh group L11 having a negative refractive power and a twelfth group L12 having a positive refractive power.
[0019]
In this embodiment, at the time of zooming from the wide-angle end to the telephoto end, the second group is moved to the image plane side as indicated by an arrow, and the image plane variation caused by zooming is caused by a convex locus on the fourth group toward the object side. It is corrected by moving while holding.
[0020]
In addition, a rear focus type is employed in which focusing is performed by moving the fourth group on the optical axis. The solid curve 4a and the dotted curve 4b of the fourth group shown in the figure show the image plane fluctuations accompanying the zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory for correction is shown. The first group and the third group are fixed during zooming and focusing.
[0021]
In the present embodiment, the fourth group is moved to correct the image plane variation accompanying zooming, and the fourth group is moved to perform focusing. In particular, as shown by the curves 4a and 4b in the figure, the zoom lens is moved so as to have a convex locus toward the object side upon zooming from the wide-angle end to the telephoto end. As a result, the space between the third group and the fourth group is effectively used, and the overall length of the lens is effectively shortened.
[0022]
In the present embodiment, as described above, the focal length fW at the wide-angle end of the entire system and the principal point interval H12W between the first group and the second group at the wide-angle end satisfy the conditional expression (1). The lens overall length is shortened while correcting various aberrations satisfactorily.
[0023]
If the lower limit of conditional expression (1) is exceeded and the principal point distance H12W between the first lens group and the second lens group is reduced, it becomes difficult to correct astigmatism and lateral chromatic aberration from the wide-angle end to the middle of the zoom. On the contrary, if the distance between the principal points exceeds the upper limit value, it becomes difficult to sufficiently reduce the front lens diameter (the effective diameter of the first group).
[0024]
Next, other features of the present embodiment will be described.
[0025]
(A1) The first group L1 includes an eleventh group L11 having a negative refractive power and a twelfth group L12 having a positive refractive power. In this way, the first lens unit L1 has a so-called retrofocus type lens configuration, so that the distance from the rear principal point of the first lens unit to the rear side surface of the first lens unit is shortened. Even if the point interval is reduced, mechanical interference is prevented.
[0026]
When the focal lengths of the eleventh lens unit L11 and the first lens unit L1 are f11 and f1, respectively.
0.75 <| f11 / f1 | <2.0 (2)
Various aberrations are satisfactorily corrected so as to satisfy the following conditional expression.
[0027]
Trying to increase the negative refractive power of the eleventh unit beyond the lower limit of conditional expression (2) is advantageous for reducing the principal point interval, but astigmatism and lateral chromatic aberration from the wide angle end to the middle of the zoom. Correction becomes difficult. Conversely, when the negative refractive power of the eleventh group becomes small beyond the upper limit, the distance between the principal points of the first group and the second group will not be sufficiently small, making it difficult to reduce the size of the entire lens system.
[0028]
(A2) The eleventh group has two negative lenses whose concave surfaces are concave, the twelfth group is a positive lens whose convex surfaces are convex, a meniscus negative lens whose convex surface faces the object side, an object A positive lens having a convex surface on the side, and a positive lens having convex surfaces on both lens surfaces.
[0029]
As a result, the entire first lens unit is sufficiently retrofocused, and the distance between the first and second lens group principal points is reduced, so that aberration correction is favorably performed and the entire lens system is reduced in size.
[0030]
(A3) In the present embodiment, in order to ensure the necessary and sufficient back focus of the optical system, a retrofocus type lens configuration including a meniscus negative lens having a convex surface facing the object side toward the object side and a positive lens. It is said.
[0031]
(A4) The fourth lens group is composed of three positive lenses and one negative lens so that aberration fluctuations associated with focusing are reduced. An aspherical surface may be used for the fourth group, and according to this, the number of lenses can be reduced.
[0032]
(A5) When the focal length of the second group is f2, and the focal lengths of the entire system at the wide-angle end and the telephoto end are fW and fT, respectively.
[0033]
[Expression 1]
To be satisfied.
[0034]
Conditional expression (3) relates to the negative refractive power of the second group, and is for effectively obtaining a predetermined zooming ratio while reducing aberration fluctuations accompanying zooming. If the refractive power of the second group becomes too strong beyond the lower limit of conditional expression (3), the entire lens system can be easily reduced in size, but the Petzval sum increases in the negative direction and the field curvature increases. As a result, the variation in aberration accompanying zooming increases. Also, if the refractive power of the second group becomes too weak beyond the upper limit, the aberration fluctuations associated with zooming will decrease, but the amount of movement of the second group to obtain a predetermined zooming ratio will increase, This is not good because the distance from the front ball increases and the front ball diameter increases.
[0035]
(A6) In this embodiment, in order to reduce the number of lenses, it is preferable to introduce an aspherical surface into each lens group, particularly the third group and the fourth group.
[0036]
Next, Embodiment 2 of FIG. 5 will be described.
[0037]
In the figure, L1 is a first group having positive refractive power, L2 is a second group having negative refractive power, L3 is a third group having positive refractive power, L4 is a fourth group having negative refractive power, and L5 is positive. This is the fifth group of refractive powers. SP is an aperture stop, which is disposed between the second group L2 and the third group L3. G is a glass block and IP is an image plane.
[0038]
When zooming from the wide-angle end to the telephoto end, the second group is moved to the image plane side as indicated by an arrow, and the image plane variation accompanying the zooming has a convex locus on the image plane side. It is moved and corrected. Further, a rear focus type is employed in which focusing is performed by moving the fourth group having negative refractive power on the optical axis.
[0039]
The solid curve 4a and the dotted curve 4b of the fourth group shown in the figure show the image plane fluctuations accompanying the zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory for correction is shown. The first group, the third group, and the fifth group are fixed during zooming and focusing.
[0040]
In this embodiment, the fourth lens unit is moved to correct image plane fluctuations accompanying zooming, and the fourth lens unit is moved to perform focusing. In particular, as shown by the curves 4a and 4b in the figure, the zoom lens is moved so as to have a convex locus toward the object side upon zooming from the wide-angle end to the telephoto end. As a result, the space between the fourth group and the fifth group is effectively used to effectively shorten the entire lens length.
[0041]
In the present embodiment, for example, when focusing from an infinitely distant object to a close object at the telephoto end, the fourth group is moved backward as indicated by a straight line 4c in FIG.
[0042]
As described above, in this embodiment, by correcting the image plane variation accompanying zooming with the fourth group having negative refractive power, the change in focal length at zooming near the wide-angle end is increased, thereby widening the image. The increase in the front lens diameter accompanying keratinization is effectively suppressed.
[0043]
In the present embodiment, in order to satisfactorily correct spherical aberration and axial chromatic aberration associated with zooming, the fourth group should have a lens configuration including at least one positive lens.
[0044]
Next, other features of the present embodiment will be described.
[0045]
(B1) In the present embodiment, as in the first embodiment, the conditional expression (1) and the conditional expressions (2) and (3) of the configurations (A1) and (A4) are satisfied.
[0046]
(B2) The eleventh group has a meniscus negative lens with a convex surface facing the object side, the twelfth group has a positive lens with both lens surfaces convex, and a meniscus negative lens with the convex surface facing the object side A positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
[0047]
This prevents an increase in the effective diameter of the front lens diameter (first group) at the time of widening the angle of view while performing aberration correction satisfactorily.
[0048]
(B3) The first group as a whole is composed of three positive lenses and two negative lenses. If the number of lens elements is further reduced, it will be difficult to suppress the variation in lateral chromatic aberration, and it will be difficult to correct spherical aberration and coma at the telephoto end.
[0049]
(B4) An aspherical surface is used for the first group in order to correct negative distortion at the wide-angle end, which is likely to occur when widening the angle of view. In particular, the aspherical surface is preferably used for the 12th group, and the shape is preferably such that the positive refractive power is stronger around the lens than the center of the lens.
[0050]
Next, Embodiment 3 of FIG. 9 will be described.
[0051]
This embodiment is different from the first embodiment in FIG. 1 in that a variable apex angle prism VP is provided between the eleventh group L11 and the twelfth group L12, and other basic configurations are the same. .
[0052]
In this embodiment, image blurring when the entire optical system vibrates is corrected by changing the prism apex angle of the variable apex angle prism VP by an actuator (not shown) based on a signal from an inclination detection sensor (not shown). ing.
[0053]
If the variable apex angle prism VP is disposed on the object side of the optical system, the diameter of the variable apex angle prism increases as the angle of view of the optical system increases.
[0054]
Therefore, in the present embodiment, the variable apex angle prism VP is arranged using the space between the eleventh group L11 and the twelfth group L12, so that the space is effectively used and the increase in the total lens length is suppressed and variable. The apex angle prism has a smaller diameter.
[0055]
In addition, by arranging the eleventh lens unit L11 having negative refractive power on the object side of the variable apex angle prism VP, the drive angle of the variable apex angle prism necessary for image stabilization is reduced.
[0056]
The variable apex angle prism VP may be driven on one side in both the vertical and horizontal directions or on both sides in the vertical and horizontal directions.
[0057]
Further, in place of the variable apex angle prism, two concavo-convex lenses having the same function may be driven to perform vibration isolation.
[0058]
Next, other features of the present embodiment will be described.
[0059]
(C1) This embodiment also satisfies the conditional expressions (1) to (3) as in the first embodiment.
[0060]
(C2) The eleventh group has two negative meniscus lenses with convex surfaces facing the object side, the twelfth group has a positive lens with convex surfaces facing both lens surfaces, and a meniscus-shaped lens with convex surfaces facing the object side. A negative lens, a positive lens having a convex surface facing the object side, and a positive lens having convex surfaces on both lens surfaces.
[0061]
As a result, the wide angle of view and the overall size of the lens system are reduced.
[0062]
Next, numerical examples of the present invention will be shown. In numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air spacing from the object side, and Ni and νi are the glasses of the i-th lens from the object side. Of the refractive index and Abbe number. Further, R33 to R39 in Numerical Example 1, R31 and R32 in Numerical Example 2, and R32 and R33 in Numerical Example 3 indicate an optical filter, a face plate, etc., but these may be omitted as necessary.
[0063]
The aspheric shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, and B, C, D, and E are aspheric coefficients, respectively. ,
[0064]
[Expression 2]
It is expressed by the following formula. “E-X” means “10 −X ”.
[0065]
Table 1 shows the relationship between the above-described conditional expressions and numerical values in the numerical examples.
[0066]
[Outside 1]
[0067]
[Outside 2]
[0068]
[Outside 3]
[0069]
[Table 1]
[0070]
【The invention's effect】
According to the present invention, by setting each element as described above, when adopting the rear focus method and widening the angle of view and increasing the zoom ratio, it is possible to prevent the enlargement of the entire lens system and To achieve a rear focus type zoom lens and a camera having the same over the entire zoom range from the end to the telephoto end, and over the entire object distance from an infinite object to a close object. Can do.
[Brief description of the drawings]
1 is a lens cross-sectional view of Numerical Example 1 of the present invention. FIG. 2 is an aberration diagram at the wide angle end of Numerical Example 1 of the present invention. FIG. 3 is an intermediate aberration diagram of Numerical Example 1 of the present invention. 4 is an aberration diagram at the telephoto end of Numerical Example 1 of the present invention. FIG. 5 is a sectional view of a lens of Numerical Example 2 of the present invention. FIG. 6 is an aberration diagram at the wide-angle end of Numerical Example 2 of the present invention. FIG. 8 is an aberration diagram at the telephoto end of Numerical Example 2 of the present invention. FIG. 9 is a lens cross-sectional view of Numerical Example 3 of the present invention. FIG. 11 is an aberration diagram at the wide-angle end of Numerical Example 3 of the invention. FIG. 11 is an intermediate aberration diagram of Numerical Example 3 of the invention. FIG. 12 is an aberration diagram at the telephoto end of Numerical Example 3 of the invention.
L1 1st group L11 11th group L12 12th group L2 2nd group L3 3rd group L4 4th group L5 5th group SP Aperture d d line g g line ΔS sagittal image plane ΔM meridional image plane

Claims (10)

  1. 物体側より順に正の屈折力の第1群、変倍用の負の屈折力の第2群、正の屈折力の第3群、そして合焦用のレンズ群を有するリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
    −5<H12W/fW<0
    0.75<|f11/f1|<2.0
    なる条件を満足することを特徴とするリヤーフォーカス式のズームレンズ。
    A rear focus type zoom lens having a first lens unit having a positive refractive power , a second lens unit having a negative refractive power for zooming, a third lens unit having a positive refractive power, and a focusing lens unit in order from the object side. The first group has two lens groups, an eleventh group having a negative refractive power and a twelfth group having a positive refractive power. The focal length at the wide angle end of the entire system is fW, and the first lens group at the wide angle end is When the main point interval between the second group and the second group is H12W, and the focal lengths of the eleventh group and the first group are f11 and f1, respectively .
    -5 <H12W / fW <0
    0.75 <| f11 / f1 | <2.0
    A rear focus zoom lens that satisfies the following conditions:
  2. 前記第11群は両レンズ面が凹面の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項1のリヤーフォーカス式のズームレンズ。The eleventh group has two negative lenses whose concave surfaces are concave, and the twelfth group is a positive lens whose convex surfaces are convex, a meniscus negative lens having a convex surface facing the object side, and a convex surface facing the object side. 2. A rear focus type zoom lens according to claim 1 , wherein the lens has a positive lens facing the lens and a positive lens having convex surfaces on both lens surfaces.
  3. 前記第11群は物体側に凸面を向けたメニスカス状の負レンズを有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項1のリヤーフォーカス式のズームレンズ。The eleventh group has a meniscus negative lens with a convex surface facing the object side, the twelfth group has a positive lens with both lens surfaces convex, a meniscus negative lens with a convex surface facing the object side, the object side 2. The rear focus zoom lens according to claim 1 , further comprising: a positive lens having a convex surface facing the lens, and a positive lens having both convex surfaces.
  4. 前記第11群は物体側に凸面を向けたメニスカス状の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項1のリヤーフォーカス式のズームレンズ。The eleventh group has two meniscus negative lenses with convex surfaces facing the object side, the twelfth group has positive lenses with convex surfaces facing both lens surfaces, meniscus negative lenses with convex surfaces facing the object side, 2. The rear focus zoom lens according to claim 1 , further comprising: a positive lens having a convex surface directed toward the object side, and a positive lens having both convex surfaces.
  5. 物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、そして正の屈折力の第4群の4つのレンズ群を有し、該第2群を像面側へ移動させて広角端から望遠端への変倍を行い、変倍に伴う像面変動を該第4群を移動させて補正すると共に該第4群を移動させてフォーカスを行うリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
    −5<H12W/fW<0
    0.75<|f11/f1|<2.0
    なる条件を満足することを特徴とするリヤーフォーカス式のズームレンズ。
    In order from the object side, there are four lens groups of a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power, The second group is moved to the image plane side to perform zooming from the wide-angle end to the telephoto end, and the image plane variation accompanying zooming is corrected by moving the fourth group, and the fourth group is moved. In a rear focus type zoom lens that performs focusing, the first group has two lens groups of an eleventh group having a negative refractive power and a twelfth group having a positive refractive power, and the focal length at the wide angle end of the entire system. FW, the principal point distance between the first group and the second group at the wide angle end is H12W, and the focal lengths of the eleventh group and the first group are f11 and f1, respectively .
    -5 <H12W / fW <0
    0.75 <| f11 / f1 | <2.0
    A rear focus zoom lens that satisfies the following conditions:
  6. 物体側より順に正の屈折力の第1群、負の屈折力の第2群、正の屈折力の第3群、負の屈折力の第4群、そして正の屈折力の第5群の5つのレンズ群を有し、該第2群を像面側へ移動させて広角端から望遠端への変倍を行い、変倍に伴う像面変動を該第4群を移動させて補正すると共に該第4群を移動させてフォーカスを行うリヤーフォーカス式のズームレンズにおいて、該第1群は負の屈折力の第11群と正の屈折力の第12群の2つのレンズ群を有し、全系の広角端の焦点距離をfW、広角端における該第1群と第2群の主点間隔をH12W、該第11群と第1群の焦点距離を各々f11、f1としたとき、
    −5<H12W/fW<0
    0.75<|f11/f1|<2.0
    なる条件を満足することを特徴とするリヤーフォーカス式のズームレンズ。
    The first group of positive refractive power, the second group of negative refractive power, the third group of positive refractive power, the fourth group of negative refractive power, and the fifth group of positive refractive power in order from the object side It has five lens groups, and the second group is moved to the image plane side to perform zooming from the wide-angle end to the telephoto end, and the image plane variation accompanying zooming is corrected by moving the fourth group. In addition, in the rear focus type zoom lens that moves the fourth group to perform focusing, the first group has two lens groups of an eleventh group having a negative refractive power and a twelfth group having a positive refractive power. When the focal length at the wide-angle end of the entire system is fW, the principal point interval between the first group and the second group at the wide-angle end is H12W, and the focal lengths of the eleventh group and the first group are f11 and f1, respectively .
    -5 <H12W / fW <0
    0.75 <| f11 / f1 | <2.0
    A rear focus zoom lens that satisfies the following conditions:
  7. 前記第11群は両レンズ面が凹面の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項5又は6のリヤーフォーカス式のズームレンズ。The eleventh group has two negative lenses whose concave surfaces are concave, and the twelfth group is a positive lens whose convex surfaces are convex, a meniscus negative lens having a convex surface facing the object side, and a convex surface facing the object side. 7. A rear focus type zoom lens according to claim 5 or 6 , characterized in that the lens has a positive lens facing the lens and a positive lens having both convex surfaces.
  8. 前記第11群は物体側に凸面を向けたメニスカス状の負レンズを有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項5又は6のリヤーフォーカス式のズームレンズ。The eleventh group has a meniscus negative lens with a convex surface facing the object side, the twelfth group has a positive lens with both lens surfaces convex, a meniscus negative lens with a convex surface facing the object side, the object side 7. The rear focus type zoom lens according to claim 5 , further comprising: a positive lens having a convex surface facing the lens, and a positive lens having both convex surfaces.
  9. 前記第11群は物体側に凸面を向けたメニスカス状の負レンズを2つ有し、前記第12群は両レンズ面が凸面の正レンズ、物体側に凸面を向けたメニスカス状の負レンズ、物体側に凸面を向けた正レンズ、そして両レンズ面が凸面の正レンズを有していることを特徴とする請求項5又は6のリヤーフォーカス式のズームレンズ。The eleventh group has two meniscus negative lenses with convex surfaces facing the object side, the twelfth group has positive lenses with convex surfaces facing both lens surfaces, meniscus negative lenses with convex surfaces facing the object side, 7. The rear focus type zoom lens according to claim 5 , further comprising: a positive lens having a convex surface directed toward the object side, and a positive lens having both lens surfaces convex.
  10. 請求項1乃至9のいずれか1項のリヤーフォーカス式のズームレンズを有していることを特徴とするカメラ。A camera comprising the rear focus zoom lens according to claim 1 .
JP27976597A 1997-09-26 1997-09-26 Rear focus zoom lens and camera having the same Expired - Fee Related JP3667054B2 (en)

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JP4510178B2 (en) * 1999-07-16 2010-07-21 キヤノン株式会社 Zoom lens
WO2005008311A1 (en) * 2003-07-17 2005-01-27 Sony Corporation Imaging device and zoom lens
JP4140011B2 (en) 2004-01-28 2008-08-27 ソニー株式会社 Zoom lens and imaging device
JP5006575B2 (en) * 2006-05-25 2012-08-22 キヤノン株式会社 Zoom lens and imaging apparatus using the same
JP5035898B2 (en) 2007-10-09 2012-09-26 富士フイルム株式会社 Rear focus type zoom lens and imaging device
JP5247237B2 (en) 2008-05-21 2013-07-24 キヤノン株式会社 Zoom lens and imaging apparatus having the same
JP2009282199A (en) 2008-05-21 2009-12-03 Canon Inc Zoom lens and imaging apparatus having the same
JP5623305B2 (en) * 2011-02-07 2014-11-12 キヤノン株式会社 Zoom lens and imaging apparatus having the same
JP6150547B2 (en) * 2013-02-12 2017-06-21 キヤノン株式会社 Zoom lens and imaging apparatus having the same

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JP3033276B2 (en) * 1991-09-18 2000-04-17 松下電器産業株式会社 Wide-angle aspheric zoom lens
JP3072815B2 (en) * 1993-10-08 2000-08-07 キヤノン株式会社 Variable power optical system
JP3466711B2 (en) * 1994-06-23 2003-11-17 キヤノン株式会社 Rear focus zoom lens
JPH08201697A (en) * 1994-10-13 1996-08-09 Fuji Photo Optical Co Ltd Zoom lens
JPH08248318A (en) * 1995-03-08 1996-09-27 Sony Corp Zoom lens
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