JP3825982B2 - Zoom lens and photographing apparatus having the same - Google Patents

Description

【００２７】
撮影レンズの一部のレンズ群ｐをＥだけ平行偏心させたときの全系の収差量Δ′Ｙは（ａ）式に示すように偏心前の収差量ΔＹと偏心によって発生した偏心収差量ΔＹ（Ｅ）との和になる。
【００２８】
ここで偏心収差ΔＹ（Ｅ）は（ｂ）式に示すように１次の偏心コマ収差（IIＥ）、１次の偏心非点収差（IIIＥ）、１次の偏心像面湾曲（ＰＥ）、１次の偏心歪曲収差（ＶＥ１）、１次の偏心歪曲付加収差（ＶＥ２）、１次の原点移動ΔＥで表される。
【００２９】
また、（ｃ）式から（ｈ）式の（IIＥ）〜（ΔＥ）までの収差は全系の焦点距離を１に規格化したとき近軸光線の偏心レンズ群への軸上マージナル光線の入射角と出射角を各々αｐ、αｐ′とし、瞳中心を通る主光線の入射角をα_pとしたときに偏心レンズ群の収差係数Ｉｐ、IIｐ、IIIｐ、Ｐｐ、Ｖｐ及び、偏心レンズ群より像側のレンズ系の収差係数Iｑ、IIｑ、IIIｑ、Ｐｑ、Ｖｑを用いて表される。
【００３０】
同様に、レンズ群ｐをＥだけ平行偏心させたときの全系の色収差量ΔｃＹａは、（ｉ）式に示すように平行偏心させる前の収差ΔｃＹと、偏心によって発生した収差ΔｃＹ（Ｅ）の和になる。
【００３１】
ここで平行偏心させる前の収差ΔｃＹ、及び偏心収差ΔｃＹ（Ｅ）は、軸上色収差Ｌ、倍率色収差Ｔ、１次の偏心色収差Ｔｅを用いてそれぞれ（ｊ）式、（ｋ）式のように表すことができる。
【００３２】
また、（ｌ）式の１次の偏心色収差係数（ＴＥ）はレンズ群ｐの色収差係数Ｌｐ、Ｔｐと、平行偏心させるレンズ群より像面側に配置されるレンズ群全体の色収差係数をＬｑ、Ｔｑを用いて表すことができる。
【００３３】
このうち、偏心による像移動を表すのが１次の原点移動（ΔＥ）であり、結像性能に影響するのは（ＩＥ）、（IIＥ）、（ＰＥ）、（ＴＥ）である。
【００３４】
偏心収差の発生を小さくするためには、第１に（ｂ）式に示すようにレンズ群ｐの偏心量Ｅを小さくすることが必要である。
【００３５】
偏心収差の発生を小さくするためには第２に、（ｃ）式〜（ｇ）式に示すレンズ群Ｐの偏心収差係数を微小とするために、レンズ群ｐの諸収差係数Ｉｐ、ＩＩｐ、ＩＩＩｐ、Ｐｐ、Ｖｐを小さな値とするか、もしくは諸収差係数を互いにうち消し合うようにバランスよく設定することが必要となってくる。
【００３６】
特に上記の（ｃ）式〜（ｇ）式に示される偏心収差係数が小さな値となるように、平行偏心させるレンズ群ｐへ入射し、このレンズ群ｐより像面側に配置されるレンズ群全体ｐの３次収差係数、及びレンズ群ｐから射出する近軸光線の換算傾角、３次収差係数、及びレンズ群pより像面側に配置されるレンズ群全体ｑの３次収差係数の値をそれぞれ適切に設定することが必要となる。すなわち、レンズ群を光軸と垂直な方向に平行偏心させたときに発生する中心画像の劣化を除去するため、主として（ｃ）式に示される１次の偏心コマ収差を良好に補正し、また同時に平行偏心させたときに発生する片ボケを良好に補正するため、主として（ｄ）式に示される１次の偏心像面湾曲を良好に補正することが必要となる。もちろんこの他の諸収差もそれぞれ良好に補正することも当然のことながら必要である。
【００３７】
偏心収差の発生を小さくするためには第３に、（ｌ）式に示される偏心色収差係数（ＴＥ）を微小とするために、レンズ群ｐとその像面側に配置されるレンズ群全体ｑの色収差係数をそれぞれ適切に設定する必要がある。
【００３８】
本発明においては、ズーム全域で防振時も高い光学性能とし、防振装置全体の小型化を図っている。
【００３９】
図１は、本実施形態の防振ズームレンズの概念図である。ここでＦは第１群としての正の屈折力のフォーカス群（前玉レンズ群）である。Ｖは第２群としての変倍用の負の屈折力のバリエータであり、光軸上を像面側へ単調に移動させることにより、広角端（ワイド）から望遠端（テレ）への変倍を行っている。Ｃは負の屈折力のコンペンセータであり、変倍に伴う像面変動を補正するために光軸上を往復軌道の移動をしている。バリエータＶとコンペンセータＣとで変倍系を構成している。ＳＰは開口絞り、Ｒは第４群としての全体として正の屈折力の固定のリレー群である。変倍に際しＦ〜Ｃまでが形成する像点Ｉ′は変化しないので、Ｒだけの結像関係を考えると、その配置および近軸追跡値は変倍に関わらず不変である。したがって、変倍移動群より像側の、変倍に際し固定の群に防振レンズ群（第ＩＳ群）を配置することにより、変倍に伴う各偏心収差係数の変動を防止できる。
【００４０】
ところで、像面上で所定の画ブレ補正量ΔＹを得るために必要な防振レンズ群の偏心量Ｅ４ｓは、（ｂ）式から、Ｒ＝０、ω＝０、αｋ′＝１として以下の式で表される。
Ｅ４ｓ＝−ΔＹ／｛２（ΔＥ）｝ （ｍ）
一次の原点移動（ΔＥ）は（ｈ）式で表されることから、必要な画ブレ補正量ΔＹを得るための偏心量Ｅ４ｓは防振レンズ群に対する軸上マージナル光線の入射換算傾角αと出射換算傾角α′で規定される。
【００４１】
そこで本実施形態では、以下の（１）式を満足させている。
−０．４５＞（α′−α） （１）
（１）式を満足しないと、偏心量Ｅ４ｓの増大によって防振レンズ群の移動量が急激に増加することに加え、偏心を考慮した防振レンズ群の有効径が増大することから、必要な駆動力が急激に増大して機構全体が大型化する。また、偏心量Ｅ４ｓの増大に伴って偏心収差の発生が大きくなるので防振時の光学性能上も良くない。
【００４２】
さらに、（１）式を満足するためには、第４群中に軸上光束を強く屈折させるレンズ構成が必要となってくる。このレンズ構成を軸上光束が強く屈折されるズームレンズの出口近傍に設定すると、駆動装置等の関係からテレビカメラとの光学的或いはメカニカルなインターフェース上の問題点が発生してしまうので好ましくない。また、第４群中にこのようなレンズ構成を新設すると屈折力の確保或いは収差補正のために必要な構成枚数が増大し、ズームレンズ全体が大型化してしまう。
【００４３】
そこで、第１群、第２群、第３群の屈折力配置を適切に設定することで、まず、変倍部をコンパクトにし、尚且つこの変倍部からの発散光線を正の屈折力の第４群の物体側の複数のレンズエレメントを利用することで収斂光線に転じさせる。
【００４４】
この結果、第４群全体の有効径の増大を抑制し、リレーレンズ部、牽いては後に詳しく述べる焦点距離変換光学系のコンパクト化を図ることができる。
【００４５】
この第４群の収斂作用の空間に適切な屈折力の負レンズを配置することで上記のような問題点を回避しつつ比較的容易に軸上光束を強く屈折させるレンズ構成を達成することが可能となる。
【００４６】
（ｃ）〜（ｇ）式の関係から、防振レンズ群による偏心収差を補正するためには、防振レンズ群の各収差係数分担値を適切に制御する必要がある。したがって防振レンズ群を少なくとも１枚ずつの正レンズと負レンズで構成するのが好ましい。それにより、防振レンズ群の各収差係数分担値の制御が容易となり、偏心収差の補正が容易になって、防振時に偏心コマ、偏心像面湾曲等の偏心諸収差が発生しにくくなる。
【００４７】
また、（ｌ）式の関係から、防振レンズ群による偏心色収差を補正するためには、防振レンズ群の各色収差係数分担値を適切に制御する必要がある。したがって防振レンズ群を構成する正レンズのアッベ数のνｐと、負レンズのアッベ数のνｎの関係を以下の（２）式を満足させるようにしている。
１０＜（νｎ−νｐ） （２）
条件式（２）を満足しないと、防振レンズ群の各色収差係数の制御が困難になり、偏心色収差の補正が困難になって、防振時に色の非対称が発生しやすくなる。
【００４８】
（ｌ）式の関係から、防振レンズ群による偏心色収差を補正するためには、防振レンズ群像面側の群の各色収差係数分担値を適切に制御する必要がある。したがって防振レンズ群の像面側に配置される第４群のその他のレンズエレメントの各色収差係数の制御が困難になり、防振レンズ群の偏心色収差の抑制が困難になって、防振時に色の非対称が発生しやすくなる。
【００４９】
そのため、例えば防振レンズ群の像面側に配置される第４群のその他のえレンズエレメントを構成する正レンズのアッベ数の平均値（νｐ（４Ｒ））と、負レンズのアッベ数の平均値（νｎ（４Ｒ））とは、以下の（３）式のような関係を満足することが望ましい。
νｐ（４Ｒ）−νｎ（４Ｒ）＞１０ （３）
すなわち、正レンズのアッベ数の平均値の方が負レンズのアッベ数の平均値よりも大きくかつその差が１０を越えるような色消しが望ましい。
【００５０】
また、（ｃ）式〜（ｇ）式の関係から、防振レンズ群による偏心収差を補正するためには、防振レンズ群の像面側の群の各収差係数分担値を適切に制御する必要がある。したがって防振レンズ群の像面側に配置される第４Ｒ群を少なくとも１枚の負レンズと複数の正レンズで構成しないと、各収差係数の制御が困難となり、偏心収差の抑制が困難になって、防振時に偏心コマ、偏心像面湾曲等の偏心諸収差が発生しやすくなる。
【００５１】
また、本実施形態においては、防振レンズ群の物体側又は像面側の近接した空間に開口絞りを配置することで軸外光線が防振レンズ群の略中央部を通過する事が可能となり防振レンズ群が偏心したときの軸外光線の光路の変化を極力抑えることができるため、特に１次の偏心像面湾曲（ＰＥ）、１次の偏心歪曲収差（ＶＥ１）、１次の偏心歪曲付加収差（ＶＥ２）等の軸外光線に係る偏心収差の変化を軽減している。
【００５２】
また、本実施形態においては、この第４群は、全系の焦点距離を変換させる焦点距離変換光学系を防振レンズ群よりも像側に光軸上に挿脱可能にしている。内臓エクステンダー等、ユニット切り換えなどの方法により、変倍域を望遠側または広角側にシフトする光学系を、防振レンズ群の像側に有することを規定しており、変換の前後で防振レンズ群の制御の変更を不要にしている。焦点距離変換光学系による焦点距離変換の前後で、防振レンズ群の物体側の配置は変化しないため、所定の補正角θを得るための防振レンズ群の偏心量Ｅは変化せず、防振レンズ群の制御を変える必要がない。
【００５３】
また、本実施形態においては、第３群を少なくとも１つの負レンズと少なくとも１つの正レンズにより構成し、その両レンズエレメントの間に適切な屈折率差、及びアッベ数差を設けることによりズーミングにおける色収差や球面収差の変動を補正することは勿論のこと、ズームレンズ全体における第４群が負担するワイド端の球面収差や色収差を軽減できるため、第４群の偏心収差への影響をも軽減することができる。
【００５４】
このように、全系の屈折力配置と変倍移動群の規定、防振レンズ群およびその像側のレンズ群の構成を適切に設定することにより、防振レンズ群の小型軽量化を図りつつ、防振レンズ群の偏心による光学性能への影響を変倍時も含め微小として、防振時も光学性能の良好な防振ズームレンズを達成することができる。
【００５５】
次に本発明の数値実施例について以下に示す。
〔数値実施例１〕
数値実施例１の諸元を表１に示す。
【００５６】
【表１】

【００５７】
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番目のレンズ面のレンズ厚又は空気間隔、ｎｉとνｉは各々物体側より順に第ｉ番目のレンズの材質の屈折率とアッベ数である。「νｉ」は、表中では「ｖｉ」と記されている。
【００５８】
ｄ１０、ｄ１８、ｄ２１は可変である。焦点距離が８．５、５１．０、１２７．５の時のそれぞれの値は表１０に示されている。これらの値は、数値実施例２、数値実施例３においても同様である。
【００５９】
【表２】

【００６０】
第１１面（ｒ１１）及び、第１８面（ｒ１８）は非球面である。
【００６１】
非球面形状は光軸方向にＸ軸、光軸と垂直方向にＨ軸、光線の進行方向を正とし、Ｒを近軸曲率半径、ｋ、Ｂ、Ｃ、Ｄ、Ｅを各々非球面係数としたとき、
【外２】

【００６２】
である。
【００６３】
参照球面Ｒ、非球面係数ｋ、Ｂ、Ｃ、Ｄ、Ｅの値は表３に示されている。表１１において、例えば「３．２１３１Ｄ^-6」とあるのは「３．２１３１×１０^-6」の意味である。これらの数値は、数値実施例２、数値実施例３においても同様である。
【００６４】
【表３】

【００６５】
図２は本発明の数値実施例１の広角端におけるレンズ断面図である。Ｆは第１群としての正の屈折力のフォーカス群（前玉レンズ群）である。Ｖは第２群としての変倍用の負の屈折力のバリエータであり、光軸上を像面側へ単調に移動させることにより、広角端（ワイド）から望遠端（テレ）への変倍を行っている。Ｃは負の屈折力のコンペンセータであり、変倍に伴う像面変動を補正するために光軸上を往復軌道の移動をしている。バリエータＶとコンペンセータＣとで変倍系を構成している。
【００６６】
ＳＰは開口絞り、Ｒは第４群としての正の屈折力の固定のリレー群である。Ｐは色分解プリズムや光学フィルター等であり、同図ではガラスブロックとして示している。
【００６７】
ｄ３５はエクステンダー挿入間隔であって、この空間に焦点距離変換光学系（ＩＥ）を挿入／排出なる切り替えによりズームレンズの広角端焦点距離を望遠側（或いは広角側）にシフトすることが可能となっている。
【００６８】
次に本実施例におけるズームレンズの第４群の特徴について説明する。第４群は負の屈折力の防振レンズ群（ＩＳ）と複数のレンズエレメントで構成されており、図４に示すように防振レンズ群は第４群の収斂光束中に配置している。また、図５に示すように焦点距離変換光学系に切換え時にも第４群内の収斂光束中に配置している。防振レンズ群は、防振用に光軸に対し略垂直な方向に移動する機能をもつ。前期防振レンズ群は１枚の負レンズと１枚の正レンズで構成されており、前記防振レンズ群への入射換算傾角をα、換算出射傾角をα′とし、前記負レンズのアッベ数をνｎ、前記正レンズのアッベ数をνｐとしたとき、各式の値は下記の値をとる。
α′−α＝−０．４９９
νｎ−νｐ＝１８．０
また、防振レンズ群より像面側に構成しているレンズエレメントは４枚の正レンズと２枚の負レンズで構成されており、これら４枚の正レンズ数の平均値は６２．１、２枚の負レンズのアッべ数の平均値は３７．９であって、正レンズのアッべ数の平均値が２４以上も大きい効果的な色消しを行っている。
【００６９】
また、（ｃ）〜（ｈ）、（ｌ）式に対応する各偏心収差係数を、防振レンズ群をｐ、防振レンズ群の像側のレンズ群をｑとして、表４に示す。
【００７０】
【表４】

【００７１】
防振レンズ群の入出射換算傾角と、防振レンズ群と防振レンズ群の像側のレンズ群の各収差係数の分担値を適切に設定することにより、防振レンズ群の各偏心収差係数を微小としている。
【００７２】
図６〜図８に数値実施例１の広角端、ｆ＝５１．０ｍｍ、望遠端の縦収差図を示す。
【００７３】
図９〜図１１に数値実施例１の広角端、ｆ＝５１．０ｍｍ、望遠端における像高０ｍｍ、±４ｍｍの横収差図を示す。
【００７４】
図１２〜図１４に数値実施例１の広角端、ｆ＝５１．０ｍｍ、望遠端において、防振レンズ群を１．０ｍｍシフトさせたときの像高０ｍｍ、±４ｍｍの横収差図を示す。
〔数値実施例２〕
数値実施例２の諸元を表５に示す。
【００７５】
【表５】

【００７６】
図１５は本発明の数値実施例２の広角端におけるレンズ断面図である。
【００７７】
図１５において、Ｆは第１群としての正の屈折力のフォ−カス群（前玉レンズ群）である。Ｖは第２群としての変倍用の負の屈折力のバリエ−タであり、光軸上を像面側へ巣調に移動させることにより、広角端（ワイド）から望遠端（テレ）への変倍を行っている。Ｃは負の屈折力のコンペンセータであり、変倍に伴う像面変動を補正するために光軸上を往復軌道の移動をしている。バリエータＶとコンペンセータＣとで変倍系を構成している。
【００７８】
ＳＰは絞り、Ｒは第４群としての正の屈折力の固定のリレー群である。Ｐは色分解プリズムや光学フィルター等であり、同図ではガラスブロックとして示している。
【００７９】
Ｒ３２からＲ３７は防振レンズ群であり、負の屈折力を有する。Ｒ３７の像面側には比較的大きな空間を有し、この空間に焦点距離変換光学系（ＩＥ）を挿入することでズームレンズ全系の焦点距離を望遠側（或いは広角側）にシフトさせる。
【００８０】
次に本実施例におけるズームレンズの第４群の特徴について説明する。第４群は負の屈折力の防振レンズ群（ＩＳ）と複数のレンズエレメントで構成されており、図１６に示すように配置している。
【００８１】
防振レンズ群が防振用に光軸に対し略垂直な方向に移動する機能をもつ。前記防振レンズ群は２枚の負レンズと１枚の正レンズで構成されており、前記防振レンズ群への入射換算傾角をα、換算出射傾角をα′とし、前記負レンズのアッベ数の平均値をνｎ、前記正レンズのアッベ数をνｐとしたとき、各式の値は下記の値をとる。
α′−α＝−０．７００
νｎ−νｐ＝１１．３６
また、防振レンズ群より像面側に構成しているレンズエレメントは４枚の正レンズと２枚の負レンズで構成されており、これら４枚の正レンズのアッベ数の平均値は６１．８、２枚の負レンズのアッベ数の平均値３９．０であって、正レンズのアッベ数の平均値が２２以上も大きい効果的な色消しを行っている。（ｃ）〜（ｈ）、（ｌ）式に対応する各偏心収差係数を、防振レンズ群をｐ、防振レンズ群の像側のレンズ群をｑとして、表６に示す。
【００８２】
【表６】

【００８３】
防振レンズ群の入出射換算傾角と、防振レンズ群と防振レンズ群の像側のレンズ群の各収差係数の分担値を適切に設定することにより、防振レンズ群の各偏心収差係数を微小としている。
【００８４】
図１７〜図１９に数値実施例２の広角端、ｆ＝５１．０ｍｍ、望遠端の縦収差図を示す。
【００８５】
図２０〜図２２に数値実施例２のｆ＝５１．０ｍｍ、望遠端における像高０ｍｍ、±４ｍｍの横収差図を示す。
【００８６】
図２３〜図２５に数値実施例２の広角端、ｆ＝５１．０ｍｍ、望遠端において、防振レンズ群を１．０ｍｍシフトさせたときの像高０ｍｍ、±４ｍｍの横収差図を示す。
〔数値実施例３〕
数値実施例３の諸元を表７に示す。
【００８７】
【表７】

【００８８】
図２６は本発明の数値実施例３の広角端におけるレンズ断面図である。Ｆは第１群としての正の屈折力のフォーカス群（前玉レンズ群）である。Ｖは第２群としての変倍用の負の屈折力のバリエータであり、光軸上を像面側へ単調に移動させることにより、広角端（ワイド）から望遠端（テレ）への変倍を行っている。Ｃは負の屈折力のコンペンセータであり、変倍に伴う像面変動を補正するために光軸上を往復軌道の移動をしている。バリエータＶとコンペンセータＣとで変倍系を構成している。
【００８９】
ＳＰは絞り、Ｒは第群としての正の屈折力の固定のリレー群である。Ｐは色分解プリズムや光学系フィルター等であり、同図ではガラスブロックとして示している。
【００９０】
Ｒ３２からＲ３７は防振レンズ群であり、負の屈折力を有する。Ｒ３７の像面側には比較的大きな空間を有し、この空間に焦点距離変換光学系（ＩＥ）を挿入することでズームレンズ全系の焦点距離を望遠側或いは広角側にシフトさせる。
【００９１】
次に本実施例におけるズームレンズの第４群の特徴について説明する。第４群は負の屈折力の防振レンズ群（ＩＳ）と複数のレンズエレメントで構成されており、図２６に示すように配置している。防振レンズ群が防振用に光軸に対し略垂直な方向に移動する機能をもつ。前記防振レンズ群は２枚の負レンズと１枚の正レンズで構成されており、前記防振レンズ群への入射換算傾角をα、換算出射傾角をα′とし、前記負レンズのアッベ数の平均値をνｎ、前記正レンズのアッベ数をνｐとしたとき、各式の値は下記のようになり、条件を満たす。
α′−α＝−０．９００
νｎ＝−νｐ＝２６．８
また、防振レンズ群より像面側に構成しているレンズエレメントは４枚の正レンズと２枚の負レンズで構成されており、これら４枚の正レンズのアッベ数の平均値は６１．１、２枚の負レンズのアッベ数の平均値は３９．０であって、正レンズのアッベ数の平均値が２２以上も大きい効果的な色消しを行っている。
【００９２】
（ｃ）〜（ｈ）、（ｌ）式に対応する各偏心収差係数を、防振レンズ群をｐ、防振レンズ群の像側のレンズ群をｑとして、表８に示す。
【００９３】
【表８】

【００９４】
防振レンズ群の入出射換算傾角と、防振レンズ群と防振レンズ群の像側のレンズ群の各収差係数の分担値を適切に設定することにより、防振レンズ群の各偏心収差係数を微小としている。
【００９５】
図２８〜図３０に数値実施例３の広角端、ｆ＝５１．０ｍｍ、望遠端の縦収差図を示す。
【００９６】
図３１〜図３３に数値実施例３の広角端、ｆ＝５１．０ｍｍ、望遠端における像高０ｍｍ、±４ｍｍの横収差図を示す。
【００９７】
図３４〜図３６に数値実施例３の広角端、ｆ＝５１．０ｍｍ、望遠端において、防振レンズ群を１．０ｍｍシフトさせたときの像高０ｍｍ、±４ｍｍの横収差図を示す。
【００９８】
次に数値実施例１から３のズームレンズを撮影光学系として用いた撮影装置（テレビカメラシステム）の実施形態を図３７を用いて説明する。
【００９９】
図３７において、１０６はレンズを含む撮影装置本体、１０１は数値実施例１から３のズームレンズによって構成された撮影光学系、１０２はフィルターや色分解プリズムに相当するガラスブロック、１０３は撮影光学系１０１によって形成される被写体像を受光するＣＣＤ等の撮像素子、１０４，１０５は撮影装置及びレンズの制御を司るＣＰＵである。
【０１００】
このように数値実施例１から３のズームレンズをテレビカメラ等の撮影装置に適用することにより、防振時においても良好な光学性能を有する撮影装置を実現することができる。
【０１０１】
【発明の効果】
以上説明した本発明によれば、所謂４群ズームレンズにおいて、全系の屈折力配置及び変倍移動群の配置を規定し、第４群の構成を規定することにより、全変倍範囲にわたり防振時についても高い光学性能を有し、機構全体が小型軽量な防振ズームレンズを提供することができる。
【図面の簡単な説明】
【図１】本発明のズームレンズの動作を説明する為の概念的光路図
【図２】本発明の数値実施例１の広角端におけるレンズ断面図
【図３】本発明の数値実施例１において焦点距離変換サブユニットを備えたレンズ断面図
【図４】数値実施例１において第４群の位置を説明するための光路図
【図５】数値実施例１において焦点距離変換サブユニットを備えた第４群の位置を説明するための図
【図６】本発明の数値実施例１の広角端における縦収差図
【図７】本発明の数値実施例１の中間焦点距離における縦収差図
【図８】本発明の数値実施例１の望遠端における縦収差図
【図９】本発明の数値実施例１の広角端における横収差図
【図１０】本発明の数値実施例１の中間焦点距離における横収差図
【図１１】本発明の数値実施例１の望遠端における横収差図
【図１２】本発明の数値実施例１の広角端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図１３】本発明の数値実施例１の中間焦点距離において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図１４】本発明の数値実施例１の望遠端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図１５】本発明の数値実施例２の広角端におけるレンズ断面図
【図１６】数値実施例２において第４群の位置を説明するための光路図
【図１７】本発明の数値実施例２の広角端における縦収差図
【図１８】本発明の数値実施例２の中間焦点距離における縦収差図
【図１９】本発明の数値実施例２の望遠端における縦収差図
【図２０】本発明の数値実施例２の広角端における横収差図
【図２１】本発明の数値実施例２の中間焦点距離における横収差図
【図２２】本発明の数値実施例２の望遠端における横収差図
【図２３】本発明の数値実施例２の広角端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図２４】本発明の数値実施例２の中間焦点距離において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図２５】本発明の数値実施例２の望遠端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図２６】本発明の数値実施例３の広角端におけるレンズ断面図
【図２７】数値実施例３において第４群の位置を説明するための光路図
【図２８】本発明の数値実施例３の広角端における縦収差図
【図２９】本発明の数値実施例３の中間焦点距離における縦収差図
【図３０】本発明の数値実施例３の望遠端における縦収差図
【図３１】本発明の数値実施例３の広角端における横収差図
【図３２】本発明の数値実施例３の中間焦点距離における横収差図
【図３３】本発明の数値実施例３の望遠端における横収差図
【図３４】本発明の数値実施例３の広角端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍのおける横収差図
【図３５】本発明の数値実施例３の中間焦点距離において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図３６】本発明の数値実施例３の望遠端において、防振レンズ群を１．０ｍｍシフトしたときの像高０ｍｍ、±４ｍｍの横収差図
【図３７】本発明のズームレンズを用いた撮影装置の摸式図
【符号の説明】
Ｆ 第１群（フォーカス群）
Ｖ 第２群（バリエータ）
Ｃ 第３群（コンペンセータ）
Ｒ 第４群（リレー群）
ＩＳ 防振レンズ群
ＩＥ 焦点距離変換光学系
ＳＰ 開口絞り
Ｐ ガラスブロック
ｅ ｅ線
ｇ ｇ線
Ｓ サジタル像面
Ｍ メリディオナル像面
ＳＨ サジタル成分の横収差
Ｉ ズームレンズ全系の像点
Ｉ′ 第１群から第３群が作る像点[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens, and in particular, by appropriately defining the refractive power arrangement of the entire system, the arrangement of the zooming movement group, and the configuration of the fourth group, it covers the entire zooming range and is particularly good at the time of image stabilization. The present invention relates to a zoom lens suitable for a television camera, a photographic camera, a video camera, and the like having optical performance as described above.
[0002]
[Prior art]
Conventionally, a zoom lens having a large aperture, a high zoom ratio and high optical performance is required for a television camera, a photographic camera, a video camera, and the like.
[0003]
In addition to this, operability and mobility are especially important for color television cameras for broadcasting, and in response to these requirements, 2 / 3-inch and 1 / 2-inch compact CCDs (solid-state image sensors) are also used as imaging devices. It has become mainstream. Since the entire imaging range of this CCD has a substantially uniform resolution, a zoom lens using the CCD is required to have a substantially uniform resolution from the center of the screen to the periphery of the screen. For example, various aberrations such as coma, astigmatism and distortion are favorably corrected, and the entire screen is required to have high optical performance. In addition, it is required to have a large aperture, wide angle, high zoom ratio, small size and light weight, and to have a long back focus because a color separation optical system and various filters are arranged in front of the imaging means. ing.
[0004]
Furthermore, suppression of image blur due to vibration and camera shake that occurs particularly when an imaging system with a long focal length is used is a serious problem, and there is an increasing demand for an image stabilization function that does not cause image blur.
[0005]
For example, in Japanese Patent Application Laid-Open No. 61-2223819, in an imaging system in which a refractive variable apex angle prism is arranged closest to the subject, an imaging system in which the refractive variable apex angle prism is arranged in response to vibration of the imaging system. The image is stabilized by changing the apex angle of the refractive variable apex angle prism corresponding to the vibration.
[0006]
In Japanese Patent Laid-Open Nos. 1-116619 and 2-124512, vibration of the photographing system is detected using an acceleration sensor or the like, and a part of the lenses of the photographing system is detected according to a signal obtained at this time. A method of obtaining a still image by vibrating a group in a direction orthogonal to the optical axis is performed.
[0007]
In JP-A-8-29738, the first group having positive refractive power, the second group having negative refractive power, the third group having negative refractive power, and the fourth group having positive refractive power are sequentially arranged from the object side. The fourth lens group is composed of two lens groups, a front group having positive refractive power and a rear group having positive refractive power, and the front group is perpendicular to the optical axis. When the zoom lens vibrates, the blur of the captured image is corrected.
[0008]
In Japanese Patent Laid-Open No. 10-90601, 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 negative refractive power, and a fourth group having a positive refractive power. A zoom lens having five lens units of the fifth group having positive refractive power, and correcting blurring of a photographed image when the fourth lens unit is moved in a direction perpendicular to the optical axis and the zoom lens vibrates. is doing.
[0009]
Japanese Patent Application Laid-Open No. 7-27978 discloses, 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 negative refractive power, and a fourth group having a positive refractive power. A zoom lens having four lens groups, wherein the fourth group comprises two lens groups, a front group having a positive refractive power and a rear group having a positive refractive power. The camera shake is corrected when the zoom lens is vibrated by moving in a direction perpendicular to the optical axis.
[0010]
[Problems to be solved by the invention]
In general, the image stabilization optical system is disposed in front of the image capturing system, and a part of the movable lens group of the image stabilization optical system is driven and controlled to eliminate blur of the captured image. In addition, a moving mechanism for moving the movable lens group becomes complicated.
[0011]
In an optical system that performs vibration isolation using a variable apex angle prism, the amount of decentered magnification chromatic aberration generated increases during image stabilization, particularly on the telephoto side.
[0012]
On the other hand, an optical system that performs anti-vibration by decentering some lenses in the photographing system in a direction perpendicular to the optical axis has the advantage that no special optical system is required for anti-vibration, but it can be moved. A space for the lens to be moved is required, and the amount of decentration aberrations generated during image stabilization increases.
[0013]
In particular, in the variable power optical system having a four-group configuration composed of four positive, negative, negative, and positive lens groups described in JP-A-8-29738, the positive front group of the fourth group is perpendicular to the optical axis. In a zoom lens that performs image stabilization by moving in any direction, the image stabilization lens group is a positive group that has a relatively small image stabilization effect (the amount of movement of the optical axis relative to the amount of eccentricity). There is a possibility that the amount of movement of the group becomes large and the drive mechanism becomes large.
[0014]
In particular, in the zoom lens having a five-group configuration including the five positive, negative, positive, negative, and positive lens groups disclosed in Japanese Patent Laid-Open No. 10-90601 described above, the fourth group is moved in the direction perpendicular to the optical axis. In the zoom lens that performs image stabilization, the fourth group is a group that moves in the direction of the optical axis during zooming, so that the drive control mechanism becomes complicated.
[0015]
SUMMARY OF THE INVENTION An object of the present invention is to provide a zoom lens and a photographing device using the same, which have a high optical performance over the entire zooming range, and have a high optical performance even during image stabilization.
[0016]
[Means for Solving the Problems]
  The 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 that moves when zooming, and a negative refractive power that moves when zooming. A zoom lens having a third group and a fourth group having a positive refractive power that is fixed at the time of zooming;
  The fourth lens group has an anti-vibration lens group having a negative refractive power in the converging space, and at least one positive lens is disposed in the fourth group on the object side of the anti-vibration lens group. Vibration lens groupIsDisplace the image by moving it so that it has a component perpendicular to the optical axis.With action,
  When the incident conversion tilt angle of the light beam incident on the anti-vibration lens group is α, and the emission conversion tilt angle of the light beam exiting from the anti-vibration lens group is α ′,
    −0.45> (α′−α)
Satisfy the conditionIt is characterized by that.
[0017]
  According to a second aspect of the present invention, in the first aspect of the invention, the anti-vibration lens group includes at least one negative lens and at least one positive lens.
[0018]
  According to a third aspect of the present invention, in the first or second aspect of the present invention, the average Abbe number of the negative lens constituting the anti-vibration lens group is νn, and the average Abbe number of the positive lens constituting the anti-vibration lens group is νp. When
    10 <(νn−νp)
It is characterized by satisfying the following conditions.
[0019]
  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the fourth group includes a plurality of positive lenses and at least one negative lens closer to the image plane side than the image stabilizing lens group. It is a feature.
[0020]
  According to a fifth aspect of the present invention, in the fourth aspect of the invention, when the average Abbe numbers of the positive lens and the negative lens disposed on the image plane side from the anti-vibration lens group are νp (4R) and νn (4R), respectively. ,
    10 <(νp (4R) −νn (4R))
It is characterized by satisfying the following conditions.
[0021]
  A sixth aspect of the invention is characterized in that, in the invention according to any one of the first to fifth aspects, an aperture stop is provided in a space close to the object side or the image plane side of the anti-vibration lens group.
[0022]
  A seventh aspect of the invention is characterized in that, in the invention of any one of the first to sixth aspects, the third group comprises at least one positive lens and at least one negative lens.
[0023]
  The zoom lens according to an eighth 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 that moves when zooming, and a negative refractive power that moves when zooming. A zoom lens having a third group and a fourth group having a positive refractive power that is fixed at the time of zooming;
  The fourth group includes an anti-vibration lens group having a negative refractive power having at least one negative lens and at least one positive lens;
  The anti-vibration lens group has an action of displacing an image by moving the anti-vibration lens group so as to have a component perpendicular to the optical axis
  The incident conversion tilt angle of the light beam incident on the image stabilization lens group is α, the emission conversion tilt angle of the light beam emitted from the image stabilization lens group is α ′, and the average Abbe number of the negative lens constituting the image stabilization lens group is νn. When the average Abbe number of the positive lenses constituting the anti-vibration lens group is νp,
    −0.45> (α′−α)
      10 <(νn−νp)
It is characterized by satisfying the following conditions.
[0024]
  According to a ninth aspect of the present invention, in the eighth aspect of the invention, the fourth group includes a plurality of positive lenses and at least one negative lens closer to the image plane side than the anti-vibration lens group.
[0025]
  According to a tenth aspect of the present invention, in the ninth aspect of the invention, when the average Abbe numbers of the positive lens and the negative lens arranged on the image plane side from the anti-vibration lens group are νp (4R) and νn (4R), respectively. ,
    10 <(νp (4R) −νn (4R))
It is characterized by satisfying the following conditions.
  According to an eleventh aspect of the present invention, in the invention according to any one of the eighth to tenth aspects, an aperture stop is provided in a space close to the object side or the image plane side of the image stabilizing lens group.
  A photographing apparatus according to a twelfth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
First, Matsui showed at the 23rd Applied Physics Lecture (1962) from the perspective of aberration theory about the occurrence of decentration aberrations when the sub-system in the optical system is decentered in the direction orthogonal to the optical axis. This will be described based on the method. Twelve mathematical expressions (a), (b), (c), (d), (e), (f), (g), (h), (i), (j), (k) used here. ) And (l) are as follows.
[Outside 1]

[0027]
The aberration amount Δ′Y of the entire system when the lens group p of a part of the taking lens is decentered by E is equal to the aberration amount ΔY before decentering and the decentering aberration amount ΔY generated by the decentering as shown in the equation (a). It becomes the sum with (E).
[0028]
Here, as shown in the equation (b), the decentering aberration ΔY (E) is the first order decentering coma aberration (IIE), the first order decentering astigmatism (IIIE), the first order decentration field curvature (PE), 1 It is expressed by the following decentration distortion aberration (VE1), the first decentration distortion additional aberration (VE2), and the first origin movement ΔE.
[0029]
In addition, the aberrations from (II) to (ΔE) in the expressions (c) to (h) are incident on the decentered lens group of paraxial rays when the focal length of the entire system is normalized to 1. The angle and the exit angle are αp and αp ′, respectively, and the incident angle of the chief ray passing through the center of the pupil is α_pIs expressed using the aberration coefficients Ip, IIp, IIIp, Pp, Vp of the decentered lens group and the aberration coefficients Iq, IIq, IIIq, Pq, Vq of the lens system on the image side from the decentered lens group.
[0030]
Similarly, the chromatic aberration amount ΔcYa of the entire system when the lens group p is decentered by E is equal to the aberration ΔcY before decentering and the aberration ΔcY (E) generated by decentering as shown in the equation (i). Become sum.
[0031]
Here, the aberration ΔcY and the decentering aberration ΔcY (E) before the parallel decentering are expressed by using the longitudinal chromatic aberration L, the lateral chromatic aberration T, and the first-order decentered chromatic aberration Te, respectively, as in the expressions (j) and (k). Can be represented.
[0032]
Further, the primary decentered chromatic aberration coefficient (TE) of the expression (l) is the chromatic aberration coefficients Lp and Tp of the lens group p, and the chromatic aberration coefficient of the entire lens group arranged on the image plane side from the lens group to be decentered in parallel is Lq, It can be expressed using Tq.
[0033]
Of these, the primary origin movement (ΔE) represents the image movement due to decentering, and (IE), (IIE), (PE), and (TE) affect the imaging performance.
[0034]
In order to reduce the occurrence of decentration aberrations, first, it is necessary to reduce the decentering amount E of the lens group p as shown in the equation (b).
[0035]
Secondly, in order to reduce the occurrence of decentration aberration, secondly, in order to make the decentration aberration coefficient of the lens group P shown in the equations (c) to (g) minute, various aberration coefficients Ip, IIp, It is necessary to set IIIp, Pp, and Vp to small values, or to set various aberration coefficients in a well-balanced manner so as to cancel each other out.
[0036]
In particular, a lens group that is incident on a lens group p that is decentered in parallel so that the decentration aberration coefficient expressed by the above formulas (c) to (g) becomes a small value and is arranged on the image plane side from the lens group p. The third-order aberration coefficient of the entire lens p, the converted tilt angle of the paraxial ray emitted from the lens group p, the third-order aberration coefficient, and the third-order aberration coefficient values of the entire lens group q arranged on the image plane side from the lens group p. Must be set appropriately. That is, in order to remove the deterioration of the central image that occurs when the lens group is decentered parallel to the direction perpendicular to the optical axis, the primary decentration coma aberration mainly expressed by the equation (c) is corrected well, and In order to satisfactorily correct the one-sided blur generated when the parallel eccentricity is performed simultaneously, it is necessary to satisfactorily correct the primary eccentric curvature of field represented by the equation (d). Of course, it is also necessary to correct these other aberrations satisfactorily.
[0037]
Thirdly, in order to reduce the occurrence of decentration aberration, thirdly, in order to make the decentration chromatic aberration coefficient (TE) shown in the expression (l) minute, the entire lens group q arranged on the lens group p and its image plane side q It is necessary to appropriately set the chromatic aberration coefficients.
[0038]
In the present invention, the entire zoom system has high optical performance even during image stabilization, and the entire image stabilization apparatus is reduced in size.
[0039]
FIG. 1 is a conceptual diagram of the image stabilizing zoom lens according to the present embodiment. Here, F denotes a focus group (front lens group) having a positive refractive power as the first group. V is a variator of negative refractive power for zooming as the second group, and zooming from the wide angle end (wide) to the telephoto end (tele) by monotonically moving on the optical surface side on the optical axis. It is carried out. C is a compensator having a negative refractive power, and moves in a reciprocating orbit on the optical axis in order to correct image plane fluctuations accompanying zooming. The variator V and the compensator C constitute a variable power system. SP is an aperture stop, and R is a fixed relay group having a positive refractive power as a whole as the fourth group. Since the image point I ′ formed by F to C at the time of zooming does not change, considering the imaging relationship of only R, the arrangement and paraxial tracking values are unchanged regardless of zooming. Therefore, by arranging the anti-vibration lens group (the IS group) in the fixed group at the time of zooming on the image side of the zooming moving group, it is possible to prevent fluctuations of each decentration aberration coefficient due to zooming.
[0040]
By the way, the decentering amount E4s of the image stabilizing lens group necessary for obtaining the predetermined image blur correction amount ΔY on the image plane is expressed by the following equation with R = 0, ω = 0, αk ′ = 1 from the equation (b). It is expressed by a formula.
E4s = −ΔY / {2 (ΔE)} (m)
Since the primary origin movement (ΔE) is expressed by the equation (h), the decentering amount E4s for obtaining the required image blur correction amount ΔY is the incident conversion inclination angle α of the on-axis marginal ray with respect to the image stabilizing lens group and the emission. It is defined by the converted inclination angle α ′.
[0041]
Therefore, in the present embodiment, the following expression (1) is satisfied.
−0.45> (α′−α) (1)
If the expression (1) is not satisfied, the amount of movement of the anti-vibration lens group increases rapidly due to the increase of the decentering amount E4s, and the effective diameter of the anti-vibration lens group considering decentering increases. The driving force increases rapidly and the entire mechanism becomes larger. Further, since the occurrence of decentration aberrations increases with an increase in the amount of decentering E4s, the optical performance during image stabilization is not good.
[0042]
Further, in order to satisfy the expression (1), a lens configuration that strongly refracts the axial light beam in the fourth group is required. If this lens configuration is set in the vicinity of the exit of the zoom lens where the axial light beam is strongly refracted, there is a problem in the optical or mechanical interface with the TV camera due to the driving device and the like, which is not preferable. In addition, when such a lens configuration is newly provided in the fourth group, the number of components necessary for securing refractive power or correcting aberrations increases, and the entire zoom lens becomes large.
[0043]
Therefore, by appropriately setting the refractive power arrangement of the first group, the second group, and the third group, first, the zoom unit is made compact, and the divergent light from the zoom unit has a positive refractive power. By using a plurality of lens elements on the object side of the fourth group, it is turned into a convergent light beam.
[0044]
As a result, an increase in the effective diameter of the entire fourth lens unit can be suppressed, and the relay lens unit and the focal length conversion optical system described in detail later can be made compact.
[0045]
By disposing a negative lens having an appropriate refractive power in the fourth group converging space, it is possible to achieve a lens configuration that refracts the axial light beam relatively easily while avoiding the above-described problems. It becomes possible.
[0046]
From the relationship of the expressions (c) to (g), in order to correct the decentration aberration caused by the image stabilizing lens group, it is necessary to appropriately control each aberration coefficient sharing value of the image stabilizing lens group. Therefore, it is preferable that the anti-vibration lens group includes at least one positive lens and one negative lens. This facilitates the control of the aberration coefficient sharing values of the image stabilizing lens group, facilitates correction of decentration aberrations, and makes it difficult for decentering aberrations such as decentering coma and decentered field curvature to occur during image stabilization.
[0047]
Further, from the relationship of the expression (l), in order to correct the decentration chromatic aberration due to the image stabilizing lens group, it is necessary to appropriately control the chromatic aberration coefficient sharing values of the image stabilizing lens group. Therefore, the relationship between the Abbe number νp of the positive lens and the Abbe number νn of the negative lens constituting the image stabilizing lens group satisfies the following expression (2).
10 <(νn−νp) (2)
If the conditional expression (2) is not satisfied, it becomes difficult to control each chromatic aberration coefficient of the image stabilizing lens group, and it becomes difficult to correct the eccentric chromatic aberration, and color asymmetry is likely to occur during image stabilization.
[0048]
In order to correct the decentration chromatic aberration due to the image stabilizing lens group from the relationship of the expression (l), it is necessary to appropriately control the chromatic aberration coefficient sharing values of the image stabilizing lens group image side. Therefore, it becomes difficult to control the chromatic aberration coefficients of the other lens elements of the fourth group arranged on the image plane side of the image stabilizing lens group, and it becomes difficult to suppress the eccentric chromatic aberration of the image stabilizing lens group. Color asymmetry tends to occur.
[0049]
Therefore, for example, the average Abbe number (νp (4R)) of the positive lenses constituting the other lens elements of the fourth group arranged on the image plane side of the image stabilizing lens group, and the average Abbe number of the negative lenses It is desirable that the value (νn (4R)) satisfies the relationship represented by the following expression (3).
νp (4R) −νn (4R)> 10 (3)
In other words, it is desirable that the average value of the Abbe number of the positive lens is larger than the average value of the Abbe number of the negative lens and that the difference exceeds 10 is achromatic.
[0050]
Further, in order to correct the decentration aberration caused by the anti-vibration lens group from the relationship of the expressions (c) to (g), each aberration coefficient sharing value of the image side group of the anti-vibration lens group is appropriately controlled. There is a need. Therefore, unless the fourth R group arranged on the image plane side of the image stabilizing lens group is composed of at least one negative lens and a plurality of positive lenses, it is difficult to control each aberration coefficient, and it is difficult to suppress decentration aberrations. Thus, various decentration aberrations such as decentering coma and decentering field curvature are likely to occur during image stabilization.
[0051]
In the present embodiment, an aperture stop is disposed in a space close to the object side or the image plane side of the image stabilizing lens group, so that off-axis rays can pass through a substantially central portion of the image stabilizing lens group. Since the change in the optical path of the off-axis light beam when the vibration-proof lens group is decentered can be suppressed as much as possible, especially the first-order decentered field curvature (PE), the first-order decentering distortion (VE1), and the first-order decentering. The change of the decentration aberration related to the off-axis ray such as the distortion additional aberration (VE2) is reduced.
[0052]
In the present embodiment, the fourth group allows a focal length conversion optical system for converting the focal length of the entire system to be inserted / removed on the optical axis closer to the image side than the image stabilizing lens group. It stipulates that the image system of the anti-vibration lens group has an optical system that shifts the zooming range to the telephoto or wide-angle side by means of unit switching, such as a built-in extender. The change of the group control is unnecessary. Before and after the focal length conversion by the focal length conversion optical system, the object side arrangement of the anti-vibration lens group does not change, so the eccentric amount E of the anti-vibration lens group for obtaining a predetermined correction angle θ does not change, and There is no need to change the control of the lens group.
[0053]
Further, in the present embodiment, the third group is constituted by at least one negative lens and at least one positive lens, and an appropriate refractive index difference and Abbe number difference are provided between the two lens elements, so that zooming can be performed. In addition to correcting fluctuations in chromatic aberration and spherical aberration, it is possible to reduce spherical aberration and chromatic aberration at the wide end that the fourth lens group in the entire zoom lens can reduce, thereby reducing the influence on decentration aberrations in the fourth lens group. be able to.
[0054]
In this way, by appropriately setting the refractive power arrangement of the entire system, the definition of the zooming movement group, and the configuration of the image stabilizing lens group and the lens group on the image side, the image stabilizing lens group can be reduced in size and weight. By reducing the influence on the optical performance due to the eccentricity of the anti-vibration lens group even when changing the magnification, it is possible to achieve an anti-vibration zoom lens having good optical performance even during the anti-vibration operation.
[0055]
Next, numerical examples of the present invention will be described below.
[Numerical Example 1]
The specifications of Numerical Example 1 are shown in Table 1.
[0056]
[Table 1]

[0057]
ri is the radius of curvature of the i-th lens surface in order from the object side, di is the lens thickness or air spacing of the i-th lens surface from the object side, and ni and νi are the materials of the i-th lens in order from the object side. Of the refractive index and Abbe number. “Νi” is described as “vi” in the table.
[0058]
d10, d18, and d21 are variable. Table 10 shows the respective values when the focal length is 8.5, 51.0, and 127.5. These values are the same in Numerical Example 2 and Numerical Example 3.
[0059]
[Table 2]

[0060]
The eleventh surface (r11) and the eighteenth surface (r18) are aspherical surfaces.
[0061]
The aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the traveling direction of the light beam is positive, R is the paraxial radius of curvature, and k, B, C, D, and E are the aspheric coefficients. When
[Outside 2]

[0062]
It is.
[0063]
Table 3 shows the values of the reference spherical surface R and the aspherical coefficients k, B, C, D, and E. In Table 11, for example, “3.2131D^-6Is "3.2131 × 10"^-6". These numerical values are the same in Numerical Example 2 and Numerical Example 3.
[0064]
[Table 3]

[0065]
FIG. 2 is a lens cross-sectional view at the wide angle end according to Numerical Embodiment 1 of the present invention. F denotes a focus group (front lens group) having a positive refractive power as the first group. V is a variator of negative refractive power for zooming as the second group, and zooming from the wide angle end (wide) to the telephoto end (tele) by monotonically moving on the optical surface side on the optical axis. It is carried out. C is a compensator having a negative refractive power, and moves in a reciprocating orbit on the optical axis in order to correct image plane fluctuations accompanying zooming. The variator V and the compensator C constitute a variable power system.
[0066]
SP is an aperture stop, and R is a fixed relay group having a positive refractive power as the fourth group. P is a color separation prism, an optical filter, or the like, and is shown as a glass block in FIG.
[0067]
d35 is an extender insertion interval, and the focal length conversion optical system (IE) is inserted into and discharged from this space, and the wide angle end focal length of the zoom lens can be shifted to the telephoto side (or the wide angle side). ing.
[0068]
Next, features of the fourth group of the zoom lens in the present embodiment will be described. The fourth group includes an anti-vibration lens group (IS) having a negative refractive power and a plurality of lens elements. As shown in FIG. 4, the anti-vibration lens group is arranged in the convergent light beam of the fourth group. . Further, as shown in FIG. 5, it is arranged in the convergent light beam in the fourth group even when switching to the focal length converting optical system. The anti-vibration lens group has a function of moving in a direction substantially perpendicular to the optical axis for anti-vibration purposes. The previous anti-vibration lens group is composed of one negative lens and one positive lens, and the incident converted inclination angle to the anti-vibration lens group is α and the converted outgoing inclination angle is α ′, and the Abbe number of the negative lens Where νn is the positive lens and νp is the Abbe number of the positive lens.
α′−α = −0.499
νn−νp = 18.0
Further, the lens element configured on the image plane side from the image stabilizing lens group includes four positive lenses and two negative lenses. The average number of these four positive lenses is 62.1. The average value of the Abbe number of the two negative lenses is 37.9, and the average value of the Abbe number of the positive lens is effectively 24 or more.
[0069]
Table 4 shows the decentration aberration coefficients corresponding to the equations (c) to (h) and (l), where p is the image stabilization lens group and q is the image side lens group of the image stabilization lens group.
[0070]
[Table 4]

[0071]
By appropriately setting the input / output converted tilt angle of the image stabilizing lens group and the respective aberration coefficient sharing values of the image stabilizing lens group and the image side lens group of the image stabilizing lens group, each eccentric aberration coefficient of the image stabilizing lens group is set. Is very small.
[0072]
6 to 8 show longitudinal aberration diagrams of Numerical Example 1 at the wide-angle end, f = 51.0 mm, and the telephoto end.
[0073]
9 to 11 show lateral aberration diagrams of Numerical Example 1 at the wide-angle end, f = 51.0 mm, and the image height at the telephoto end of 0 mm and ± 4 mm.
[0074]
FIGS. 12 to 14 show lateral aberration diagrams of the image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the wide-angle end, f = 51.0 mm, and the telephoto end of Numerical Example 1. FIG.
[Numerical Example 2]
Specifications of Numerical Example 2 are shown in Table 5.
[0075]
[Table 5]

[0076]
FIG. 15 is a lens cross-sectional view at the wide angle end according to Numerical Embodiment 2 of the present invention.
[0077]
In FIG. 15, F is a positive refractive power focus group (front lens group) as the first group. V is a variator of negative refractive power for zooming as the second group, and moves from the wide-angle end (wide) to the telephoto end (tele) by moving the optical axis in the nest to the image plane side. The zooming is done. C is a compensator having a negative refractive power, and moves in a reciprocating orbit on the optical axis in order to correct image plane fluctuations accompanying zooming. The variator V and the compensator C constitute a variable power system.
[0078]
SP is a stop, and R is a fixed relay group having a positive refractive power as the fourth group. P is a color separation prism, an optical filter, or the like, and is shown as a glass block in FIG.
[0079]
R32 to R37 are anti-vibration lens groups and have negative refractive power. There is a relatively large space on the image plane side of R37, and the focal length conversion optical system (IE) is inserted into this space to shift the focal length of the entire zoom lens system to the telephoto side (or wide angle side).
[0080]
Next, features of the fourth group of the zoom lens in the present embodiment will be described. The fourth group includes an anti-vibration lens group (IS) having a negative refractive power and a plurality of lens elements, which are arranged as shown in FIG.
[0081]
The anti-vibration lens group has a function of moving in a direction substantially perpendicular to the optical axis for image stabilization. The anti-vibration lens group is composed of two negative lenses and one positive lens. The incident converted inclination angle to the anti-vibration lens group is α, the converted outgoing inclination angle is α ′, and the Abbe number of the negative lens When the average value of νn is νn and the Abbe number of the positive lens is νp, the values of the respective expressions are as follows.
α′−α = −0.700
νn−νp = 11.36
Further, the lens element configured on the image plane side from the image stabilizing lens group includes four positive lenses and two negative lenses. The average value of the Abbe number of these four positive lenses is 61.degree. The average value of the Abbe number of the two negative lenses is 39.0, and the average value of the Abbe number of the positive lens is 22 or more. Table 6 shows the decentration aberration coefficients corresponding to the equations (c) to (h) and (l), where p is the image stabilization lens group and q is the image side lens group of the image stabilization lens group.
[0082]
[Table 6]

[0083]
By appropriately setting the input / output converted tilt angle of the image stabilizing lens group and the respective aberration coefficient sharing values of the image stabilizing lens group and the image side lens group of the image stabilizing lens group, each eccentric aberration coefficient of the image stabilizing lens group is set. Is very small.
[0084]
17 to 19 are longitudinal aberration diagrams of Numerical Example 2 at the wide-angle end, f = 51.0 mm, and the telephoto end.
[0085]
20 to 22 show lateral aberration diagrams of Numerical Example 2 at f = 51.0 mm, the image height at the telephoto end of 0 mm, and ± 4 mm.
[0086]
FIGS. 23 to 25 are lateral aberration diagrams of image height 0 mm and ± 4 mm when the anti-vibration lens group is shifted 1.0 mm at the wide angle end, f = 51.0 mm, and the telephoto end according to Numerical Example 2. FIG.
[Numerical Example 3]
Table 7 shows the data of Numerical Example 3.
[0087]
[Table 7]

[0088]
FIG. 26 is a lens cross-sectional view at the wide angle end according to Numerical Embodiment 3 of the present invention. F denotes a focus group (front lens group) having a positive refractive power as the first group. V is a variator of negative refractive power for zooming as the second group, and zooming from the wide angle end (wide) to the telephoto end (tele) by monotonically moving on the optical surface side on the optical axis. It is carried out. C is a compensator having a negative refractive power, and moves in a reciprocating orbit on the optical axis in order to correct image plane fluctuations accompanying zooming. The variator V and the compensator C constitute a variable power system.
[0089]
SP is a stop, and R is a fixed relay group having a positive refractive power as the first group. P is a color separation prism, an optical system filter or the like, and is shown as a glass block in the figure.
[0090]
R32 to R37 are anti-vibration lens groups and have negative refractive power. There is a relatively large space on the image plane side of R37, and the focal length conversion optical system (IE) is inserted into this space to shift the focal length of the entire zoom lens system to the telephoto side or wide angle side.
[0091]
Next, features of the fourth group of the zoom lens in the present embodiment will be described. The fourth group includes an anti-vibration lens group (IS) having a negative refractive power and a plurality of lens elements, which are arranged as shown in FIG. The anti-vibration lens group has a function of moving in a direction substantially perpendicular to the optical axis for image stabilization. The anti-vibration lens group is composed of two negative lenses and one positive lens, the incident conversion tilt angle to the anti-vibration lens group is α, the converted output tilt angle is α ′, and the Abbe number of the negative lens When the average value of νn is νn and the Abbe number of the positive lens is νp, the values of the respective expressions are as follows and satisfy the condition.
α′−α = −0.900
νn = −νp = 26.8
Further, the lens element configured on the image plane side from the image stabilizing lens group includes four positive lenses and two negative lenses. The average value of the Abbe number of these four positive lenses is 61.degree. The average value of the Abbe numbers of the one and two negative lenses is 39.0, and the average value of the Abbe numbers of the positive lenses is effectively 22 or more.
[0092]
Table 8 shows the decentration aberration coefficients corresponding to the equations (c) to (h) and (l), where p is the image stabilization lens group and q is the image side lens group of the image stabilization lens group.
[0093]
[Table 8]

[0094]
By properly setting the input / output conversion tilt angle of the anti-vibration lens group and the respective aberration coefficients of the image side lens group of the anti-vibration lens group and the anti-vibration lens group, each decentration aberration coefficient of the anti-vibration lens group is set. Is very small.
[0095]
28 to 30 are longitudinal aberration diagrams of Numerical Example 3 at the wide-angle end, f = 51.0 mm, and the telephoto end.
[0096]
FIGS. 31 to 33 show lateral aberration diagrams of Numerical Example 3 at the wide-angle end, f = 51.0 mm, and the image height 0 mm and ± 4 mm at the telephoto end.
[0097]
FIG. 34 to FIG. 36 show lateral aberration diagrams of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the wide-angle end, f = 51.0 mm, and the telephoto end of Numerical Example 3.
[0098]
Next, an embodiment of a photographing apparatus (television camera system) using the zoom lenses of Numerical Examples 1 to 3 as a photographing optical system will be described with reference to FIG.
[0099]
In FIG. 37, reference numeral 106 denotes a photographing apparatus main body including a lens, 101 denotes a photographing optical system constituted by the zoom lenses of Numerical Examples 1 to 3, 102 denotes a glass block corresponding to a filter or a color separation prism, and 103 denotes a photographing optical system. An image sensor such as a CCD that receives a subject image formed by the camera 101, and 104 and 105 are CPUs that control the photographing apparatus and the lens.
[0100]
Thus, by applying the zoom lenses of Numerical Examples 1 to 3 to a photographing apparatus such as a television camera, it is possible to realize a photographing apparatus having good optical performance even during image stabilization.
[0101]
【The invention's effect】
According to the present invention described above, in a so-called four-group zoom lens, the refractive power arrangement of the entire system and the arrangement of the zooming movement group are defined, and the configuration of the fourth group is defined, thereby preventing the entire zooming range. It is possible to provide a vibration-proof zoom lens that has high optical performance even when shaken, and has a small and light overall mechanism.
[Brief description of the drawings]
FIG. 1 is a conceptual optical path diagram for explaining the operation of a zoom lens according to the present invention.
FIG. 2 is a lens cross-sectional view at a wide angle end according to Numerical Embodiment 1 of the present invention.
FIG. 3 is a cross-sectional view of a lens provided with a focal length conversion subunit in Numerical Example 1 of the present invention.
FIG. 4 is an optical path diagram for explaining the position of the fourth group in Numerical Example 1;
FIG. 5 is a diagram for explaining the position of a fourth group that includes a focal length conversion subunit in Numerical Example 1;
FIG. 6 is a longitudinal aberration diagram at the wide-angle end according to Numerical Example 1 of the present invention.
FIG. 7 is a longitudinal aberration diagram at the intermediate focal length according to Numerical Example 1 of the present invention.
FIG. 8 is a longitudinal aberration diagram at the telephoto end according to Numerical Example 1 of the present invention.
FIG. 9 is a lateral aberration diagram at the wide-angle end according to Numerical Example 1 of the present invention.
FIG. 10 is a lateral aberration diagram at the intermediate focal length according to Numerical Example 1 of the present invention.
FIG. 11 is a lateral aberration diagram at the telephoto end according to Numerical Example 1 of the present invention.
12 is a lateral aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the wide angle end according to Numerical Example 1 of the present invention. FIG.
13 is a lateral aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the intermediate focal length according to Numerical Example 1 of the present invention. FIG.
FIG. 14 is a lateral aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the telephoto end according to Numerical Example 1 of the present invention.
15 is a lens cross-sectional view at the wide-angle end according to Numerical Embodiment 2 of the present invention. FIG.
FIG. 16 is an optical path diagram for explaining the position of the fourth group in Numerical Example 2.
FIG. 17 is a longitudinal aberration diagram at the wide-angle end according to Numerical Example 2 of the present invention.
FIG. 18 is a longitudinal aberration diagram at the intermediate focal length according to Numerical Example 2 of the present invention.
FIG. 19 is a longitudinal aberration diagram at the telephoto end according to Numerical Example 2 of the present invention.
FIG. 20 is a transverse aberration diagram at the wide-angle end according to Numerical Example 2 of the present invention.
FIG. 21 is a lateral aberration diagram at the intermediate focal length according to Numerical Example 2 of the present invention.
FIG. 22 is a lateral aberration diagram at the telephoto end according to Numerical Example 2 of the present invention.
FIG. 23 is a transverse aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the wide angle end according to Numerical Example 2 of the present invention.
FIG. 24 is a lateral aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the intermediate focal length according to Numerical Embodiment 2 of the present invention.
FIG. 25 is a transverse aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the telephoto end according to Numerical Example 2 of the present invention.
FIG. 26 is a lens cross-sectional view at the wide angle end according to Numerical Embodiment 3 of the present invention.
FIG. 27 is an optical path diagram for explaining the position of the fourth group in Numerical Example 3.
FIG. 28 is a longitudinal aberration diagram at the wide-angle end according to Numerical Example 3 of the present invention.
FIG. 29 is a longitudinal aberration diagram at the intermediate focal length according to Numerical Example 3 of the present invention.
FIG. 30 is a longitudinal aberration diagram at the telephoto end according to Numerical Example 3 of the present invention.
FIG. 31 is a lateral aberration diagram at the wide-angle end according to Numerical Example 3 of the present invention.
FIG. 32 is a lateral aberration diagram at the intermediate focal length according to Numerical Example 3 of the present invention.
FIG. 33 is a lateral aberration diagram at the telephoto end according to Numerical Example 3 of the present invention.
FIG. 34 is a lateral aberration diagram at an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the wide angle end according to Numerical Example 3 of the present invention;
FIG. 35 is a transverse aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the intermediate focal length according to Numerical Example 3 of the present invention.
FIG. 36 is a lateral aberration diagram of an image height of 0 mm and ± 4 mm when the image stabilizing lens unit is shifted by 1.0 mm at the telephoto end according to Numerical Example 3 of the present invention.
FIG. 37 is a schematic diagram of a photographing apparatus using the zoom lens of the present invention.
[Explanation of symbols]
F 1st group (focus group)
V 2nd group (variator)
C Group 3 (Compensator)
R 4th group (relay group)
IS anti-vibration lens group
IE focal length conversion optical system
SP Aperture stop
P glass block
e line
g g line
S Sagittal image plane
M Meridional image
SH Transverse aberration of sagittal component
I Image points of the entire zoom lens system
I 'Image points created by the first to third groups

Claims (12)

In order from the object side, the first group of positive refractive power, the second group of negative refractive power that moves when zooming, the third group of negative power that moves when zooming, and the fixed group when zooming A zoom lens having a fourth lens unit having a positive refractive power,
The fourth lens group has an anti-vibration lens group having a negative refractive power in the converging space, and at least one positive lens is disposed in the fourth group on the object side of the anti-vibration lens group. The vibration lens group has an action of displacing the image by moving it so as to have a component in a direction perpendicular to the optical axis ,
When the incident conversion tilt angle of the light beam incident on the anti-vibration lens group is α, and the emission conversion tilt angle of the light beam exiting from the anti-vibration lens group is α ′,
−0.45> (α′−α)
A zoom lens characterized by satisfying the following conditions:   The zoom lens according to claim 1, wherein the anti-vibration lens group includes at least one negative lens and at least one positive lens. When the average Abbe number of the negative lens constituting the image stabilizing lens group is νn and the average Abbe number of the positive lens constituting the image stabilizing lens group is νp,
10 <(νn−νp)
The zoom lens according to claim 1 or 2, characterized by satisfying the following condition. The fourth group, the zoom lens according to any one of claims 1 to 3, characterized in that it has the anti-vibration lens at least one negative lens and a plurality of positive lenses on the image plane side group. When the average Abbe numbers of the positive lens and the negative lens arranged on the image plane side from the image stabilizing lens group are νp (4R) and νn (4R), respectively.
10 <(νp (4R) −νn (4R))
The zoom lens according to claim 4 , wherein the following condition is satisfied. The vibration-proof lens group on the object side or the space proximate the image plane side, a zoom lens according to claim 1, any one of 5, characterized in that an aperture stop. The zoom lens according to any one of claims 1 to 6 , wherein the third group includes at least one positive lens and at least one negative lens. In order from the object side, the first group of positive refractive power, the second group of negative refractive power that moves when zooming, the third group of negative power that moves when zooming, and the fixed group when zooming A zoom lens having a fourth lens unit having a positive refractive power,
The fourth group includes an anti-vibration lens group having a negative refractive power having at least one negative lens and at least one positive lens;
The anti-vibration lens group has an action of displacing an image by moving the anti-vibration lens group so as to have a component perpendicular to the optical axis,
The incident conversion tilt angle of the light incident on the image stabilization lens group is α, the exit conversion tilt angle of the light beam exiting from the image stabilization lens group is α ′, and the average Abbe number of the negative lens constituting the image stabilization lens group is νn. When the average Abbe number of the positive lenses constituting the anti-vibration lens group is νp,
−0.45> (α′−α)
10 <(νn−νp)
A zoom lens that satisfies the following conditions: 9. The zoom lens according to claim 8 , wherein the fourth group includes a plurality of positive lenses and at least one negative lens closer to the image plane than the image stabilizing lens group. When the average Abbe numbers of the positive lens and the negative lens arranged on the image plane side from the image stabilizing lens group are νp (4R) and νn (4R), respectively.
10 <(νp (4R) −νn (4R))
The zoom lens according to claim 9 , wherein the following condition is satisfied. Wherein the adjacent space of the object side or the image surface side of the vibration reduction lens group, a zoom lens according to claims 8 to any one of 10, characterized in that an aperture stop. An imaging apparatus comprising the zoom lens according to any one of claims 1 to 11 .

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