JP3994212B2 - Variable-magnification optical system capable of image shift - Google Patents

Description

各実施例において、非球面には面番号の右側に＊印を付している。
【００５６】
〔第１実施例〕
図２は、本発明の第１実施例にかかる変倍光学系の構成を示す図である。
図２の変倍光学系において、第１レンズ群Ｇ１は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ１から構成されている。
また、第２レンズ群Ｇ２は、物体側から順に、両凹レンズＬ21、および両凸レンズＬ22から構成されている。
さらに、第３レンズ群Ｇ３は、両凹レンズＬ３から構成されている。
【００５７】
また、第４レンズ群Ｇ４は、物体側から順に、両凸レンズＬ41、および両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ42から構成されている。
さらに、第５レンズ群Ｇ５は、物体側から順に、物体側に凹面を向けた正メニスカスレンズＬ51、両凹レンズＬ52、および物体側に凹面を向けた負メニスカスレンズＬ53から構成されている。
【００５８】
また、開口絞りＳは、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間に配置され、広角端状態から望遠端状態への変倍に際して第４レンズ群Ｇ４と一体的に移動する。
図２は、広角端状態における各レンズ群の位置関係を示しており、望遠端状態への変倍時には図１に矢印で示すズーム軌道に沿って光軸上を移動する。
また、第４レンズ群Ｇ４を構成する２つのレンズ成分のうち接合正レンズＬ42を光軸にほぼ垂直な方向に移動させて像シフトを行い、手ぶれ等に起因する像位置の変動を補正している。すなわち、接合正レンズＬ42は、シフトレンズ群である部分レンズ群Ｇｈを構成している。
さらに、第３レンズ群Ｇ３を光軸に沿って移動させることにより、フォーカシング（合焦）を行っている。
【００５９】
次の表（１）に、本発明の第１実施例の諸元の値を掲げる。表（１）において、ｆは焦点距離を、ＦNOはＦナンバーを、ωは半画角を、Ｂｆはバックフォーカスを、Ｄ0 は物体と最も物体側の面との光軸に沿った距離をそれぞれ表している。さらに、面番号は光線の進行する方向に沿った物体側からのレンズ面の順序を、屈折率およびアッベ数はそれぞれｄ線（λ＝５８７．６ｎｍ）に対する値を示している。
【００６０】
【表１】

【００６１】
図３乃至図１０は、ｄ線（λ＝５８７．６ｎｍ）に対する第１実施例の諸収差図である。図３は広角端状態（最短焦点距離状態）における無限遠合焦状態での諸収差図であり、図４は第１中間焦点距離状態における無限遠合焦状態での諸収差図であり、図５は第２中間焦点距離状態における無限遠合焦状態での諸収差図であり、図６は望遠端状態（最長焦点距離状態）における無限遠合焦状態での諸収差図である。
また、図７は広角端状態における撮影倍率−１／３０倍での諸収差図であり、図８は第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図９は第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図１０は望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【００６２】
さらに、図１１乃至図１８は、第１実施例において光軸に対して０．０１rad （ラジアン）だけ像シフトさせたときのコマ収差図である。図１１は、広角端状態における無限遠合焦状態でのコマ収差図であり、図１２は第１中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図１３は第２中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図１４は望遠端状態における無限遠合焦状態でのコマ収差図である。
また、図１５は、広角端状態における撮影倍率−１／３０倍でのコマ収差図であり、図１６は第１中間焦点距離状態における撮影倍率−１／３０倍でのコマ差図であり、図１７は第２中間焦点距離状態における撮影倍率−１／３０倍でのコマ収差図であり、図１８は望遠端状態における撮影倍率−１／３０倍でのコマ収差図である。
図１１乃至図１８の各収差図は、像高Ｙの正方向に接合正レンズＬ42を移動させたときのＹ＝１５．０，０，−１５．０でのコマ収差を示している。
【００６３】
各収差図において、ＦNOはＦナンバーを、ＮＡは開口数を、Ｙは像高を、Ａは各像高に対する半画角を、Ｈは各像高に対する物体高をそれぞれ示している。
また、非点収差を示す収差図において、実線はサジタル像面を示し、破線はメリディオナル像面を示している。さらに、球面収差を示す収差図において、破線はサインコンディション（正弦条件）を示している。
各収差図から明らかなように、本実施例では、各撮影距離状態および各焦点距離状態において像シフト時にも諸収差が良好に補正されていることがわかる。
【００６４】
〔第２実施例〕
図１９は、本発明の第２実施例にかかる変倍光学系の構成を示す図である。
図１９の変倍光学系において、第１レンズ群Ｇ１は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ１から構成されている。
また、第２レンズ群Ｇ２は、物体側から順に、両凹レンズＬ21、および両凸レンズＬ22から構成されている。
さらに、第３レンズ群Ｇ３は、両凹レンズＬ３から構成されている。
【００６５】
また、第４レンズ群Ｇ４は、物体側から順に、両凸レンズＬ41、および両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ42から構成されている。
さらに、第５レンズ群Ｇ５は、物体側から順に、両凸レンズＬ51、両凹レンズＬ52、および物体側に凹面を向けた負メニスカスレンズＬ53から構成されている。
【００６６】
また、開口絞りＳは、第４レンズ群Ｇ４中に配置され、広角端状態から望遠端状態への変倍に際して第４レンズ群Ｇ４と一体的に移動する。
図１９は、広角端状態における各レンズ群の位置関係を示しており、望遠端状態への変倍時には図１に矢印で示すズーム軌道に沿って光軸上を移動する。
また、第４レンズ群Ｇ４を構成する２つのレンズ成分のうち接合正レンズＬ42を光軸にほぼ垂直な方向に移動させて像シフトを行い、手ぶれ等に起因する像位置の変動を補正している。すなわち、接合正レンズＬ42は、シフトレンズ群である部分レンズ群Ｇｈを構成している。
さらに、第３レンズ群Ｇ３を光軸に沿って移動させることにより、フォーカシング（合焦）を行っている。
【００６７】
次の表（２）に、本発明の第２実施例の諸元の値を掲げる。表（２）において、ｆは焦点距離を、ＦNOはＦナンバーを、ωは半画角を、Ｂｆはバックフォーカスを、Ｄ0 は物体と最も物体側の面との光軸に沿った距離をそれぞれ表している。さらに、面番号は光線の進行する方向に沿った物体側からのレンズ面の順序を、屈折率およびアッベ数はそれぞれｄ線（λ＝５８７．６ｎｍ）に対する値を示している。
【００６８】
【表２】

【００６９】
図２０乃至図２７は、ｄ線（λ＝５８７．６ｎｍ）に対する第２実施例の諸収差図である。図２０は広角端状態における無限遠合焦状態での諸収差図であり、図２１は第１中間焦点距離状態における無限遠合焦状態での諸収差図であり、図２２は第２中間焦点距離状態における無限遠合焦状態での諸収差図であり、図２３は望遠端状態における無限遠合焦状態での諸収差図である。
また、図２４は広角端状態における撮影倍率−１／３０倍での諸収差図であり、図２５は第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図２６は第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図２７は望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【００７０】
さらに、図２８乃至図３５は、第２実施例において光軸に対して０．０１rad （ラジアン）だけ像シフトさせたときのコマ収差図である。図２８は、広角端状態における無限遠合焦状態でのコマ収差図であり、図２９は第１中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図３０は第２中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図３１は望遠端状態における無限遠合焦状態でのコマ収差図である。
また、図３２は、広角端状態における撮影倍率−１／３０倍でのコマ収差図であり、図３３は第１中間焦点距離状態における撮影倍率−１／３０倍でのコマ差図であり、図３４は第２中間焦点距離状態における撮影倍率−１／３０倍でのコマ収差図であり、図３５は望遠端状態における撮影倍率−１／３０倍でのコマ収差図である。
図２８乃至図３５の各収差図は、像高Ｙの正方向に接合正レンズＬ42を移動させたときのＹ＝１５．０，０，−１５．０でのコマ収差を示している。
【００７１】
各収差図において、ＦNOはＦナンバーを、ＮＡは開口数を、Ｙは像高を、Ａは各像高に対する半画角を、Ｈは各像高に対する物体高をそれぞれ示している。
また、非点収差を示す収差図において、実線はサジタル像面を示し、破線はメリディオナル像面を示している。さらに、球面収差を示す収差図において、破線はサインコンディション（正弦条件）を示している。
各収差図から明らかなように、本実施例では、各撮影距離状態および各焦点距離状態において像シフト時にも諸収差が良好に補正されていることがわかる。
【００７２】
〔第３実施例〕
図３６は、本発明の第３実施例にかかる変倍光学系の構成を示す図である。
図３６の変倍光学系において、第１レンズ群Ｇ１は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ１から構成されている。
また、第２レンズ群Ｇ２は、物体側から順に、両凹レンズＬ21、および両凸レンズＬ22から構成されている。
さらに、第３レンズ群Ｇ３は、両凹レンズＬ３から構成されている。
【００７３】
また、第４レンズ群Ｇ４は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ41、および両凸レンズＬ42から構成されている。
さらに、第５レンズ群Ｇ５は、物体側から順に、物体側に凹面を向けた正メニスカスレンズＬ51、両凹レンズＬ52、および物体側に凹面を向けた負メニスカスレンズＬ53から構成されている。
【００７４】
また、開口絞りＳは、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間に配置され、広角端状態から望遠端状態への変倍に際して第４レンズ群Ｇ４と一体的に移動する。
図３６は、広角端状態における各レンズ群の位置関係を示しており、望遠端状態への変倍時には図１に矢印で示すズーム軌道に沿って光軸上を移動する。
また、第４レンズ群Ｇ４を構成する２つのレンズ成分のうち接合正レンズＬ41を光軸にほぼ垂直な方向に移動させて像シフトを行い、手ぶれ等に起因する像位置の変動を補正している。すなわち、接合正レンズＬ41は、シフトレンズ群である部分レンズ群Ｇｈを構成している。
さらに、第３レンズ群Ｇ３を光軸に沿って移動させることにより、フォーカシング（合焦）を行っている。
【００７５】
次の表（３）に、本発明の第３実施例の諸元の値を掲げる。表（３）において、ｆは焦点距離を、ＦNOはＦナンバーを、ωは半画角を、Ｂｆはバックフォーカスを、Ｄ0 は物体と最も物体側の面との光軸に沿った距離をそれぞれ表している。さらに、面番号は光線の進行する方向に沿った物体側からのレンズ面の順序を、屈折率およびアッベ数はそれぞれｄ線（λ＝５８７．６ｎｍ）に対する値を示している。
【００７６】
【表３】

【００７７】
図３７乃至図４４は、ｄ線（λ＝５８７．６ｎｍ）に対する第３実施例の諸収差図である。図３７は広角端状態における無限遠合焦状態での諸収差図であり、図３８は第１中間焦点距離状態における無限遠合焦状態での諸収差図であり、図３９は第２中間焦点距離状態における無限遠合焦状態での諸収差図であり、図４０は望遠端状態における無限遠合焦状態での諸収差図である。
また、図４１は広角端状態における撮影倍率−１／３０倍での諸収差図であり、図４２は第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図４３は第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図４４は望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【００７８】
さらに、図４５乃至図５２は、第３実施例において光軸に対して０．０１rad （ラジアン）だけ像シフトさせたときのコマ収差図である。図４５は、広角端状態における無限遠合焦状態でのコマ収差図であり、図４６は第１中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図４７は第２中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図４８は望遠端状態における無限遠合焦状態でのコマ収差図である。
また、図４９は、広角端状態における撮影倍率−１／３０倍でのコマ収差図であり、図５０は第１中間焦点距離状態における撮影倍率−１／３０倍でのコマ差図であり、図５１は第２中間焦点距離状態における撮影倍率−１／３０倍でのコマ収差図であり、図５２は望遠端状態における撮影倍率−１／３０倍でのコマ収差図である。
図４５乃至図５２の各収差図は、像高Ｙの正方向に接合正レンズＬ41を移動させたときのＹ＝１５．０，０，−１５．０でのコマ収差を示している。
【００７９】
各収差図において、ＦNOはＦナンバーを、ＮＡは開口数を、Ｙは像高を、Ａは各像高に対する半画角を、Ｈは各像高に対する物体高をそれぞれ示している。
また、非点収差を示す収差図において、実線はサジタル像面を示し、破線はメリディオナル像面を示している。さらに、球面収差を示す収差図において、破線はサインコンディション（正弦条件）を示している。
各収差図から明らかなように、本実施例では、各撮影距離状態および各焦点距離状態において像シフト時にも諸収差が良好に補正されていることがわかる。
【００８０】
〔第４実施例〕
図５３は、本発明の第４実施例にかかる変倍光学系の構成を示す図である。
図５３の変倍光学系において、第１レンズ群Ｇ１は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ１から構成されている。
また、第２レンズ群Ｇ２は、物体側から順に、両凹レンズＬ21、および両凸レンズＬ22から構成されている。
さらに、第３レンズ群Ｇ３は、両凹レンズＬ３から構成されている。
【００８１】
また、第４レンズ群Ｇ４は、物体側から順に、両凸レンズと物体側に凹面を向けた負メニスカスレンズとの接合正レンズＬ41、および両凸レンズＬ42から構成されている。
さらに、第５レンズ群Ｇ５は、物体側から順に、物体側に凹面を向けた正メニスカスレンズＬ51、両凹レンズＬ52、および物体側に凹面を向けた負メニスカスレンズＬ53から構成されている。
【００８２】
また、開口絞りＳは、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間に配置され、広角端状態から望遠端状態への変倍に際して第４レンズ群Ｇ４と一体的に移動する。
図５３は、広角端状態における各レンズ群の位置関係を示しており、望遠端状態への変倍時には図１に矢印で示すズーム軌道に沿って光軸上を移動する。
また、第４レンズ群Ｇ４を構成する２つのレンズ成分のうち接合正レンズＬ41を光軸にほぼ垂直な方向に移動させて像シフトを行い、手ぶれ等に起因する像位置の変動を補正している。すなわち、接合正レンズＬ41は、シフトレンズ群である部分レンズ群Ｇｈを構成している。
さらに、第３レンズ群Ｇ３を光軸に沿って移動させることにより、フォーカシング（合焦）を行っている。
【００８３】
次の表（４）に、本発明の第４実施例の諸元の値を掲げる。表（４）において、ｆは焦点距離を、ＦNOはＦナンバーを、ωは半画角を、Ｂｆはバックフォーカスを、Ｄ0 は物体と最も物体側の面との光軸に沿った距離をそれぞれ表している。さらに、面番号は光線の進行する方向に沿った物体側からのレンズ面の順序を、屈折率およびアッベ数はそれぞれｄ線（λ＝５８７．６ｎｍ）に対する値を示している。
【００８４】
【表４】

【００８５】
図５４乃至図６１は、ｄ線（λ＝５８７．６ｎｍ）に対する第４実施例の諸収差図である。図５４は広角端状態における無限遠合焦状態での諸収差図であり、図５５は第１中間焦点距離状態における無限遠合焦状態での諸収差図であり、図５６は第２中間焦点距離状態における無限遠合焦状態での諸収差図であり、図５７は望遠端状態における無限遠合焦状態での諸収差図である。
また、図５８は広角端状態における撮影倍率−１／３０倍での諸収差図であり、図５９は第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図６０は第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図であり、図６１は望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【００８６】
さらに、図６２乃至図６９は、第４実施例において光軸に対して０．０１rad （ラジアン）だけ像シフトさせたときのコマ収差図である。図６２は、広角端状態における無限遠合焦状態でのコマ収差図であり、図６３は第１中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図６４は第２中間焦点距離状態における無限遠合焦状態でのコマ収差図であり、図６５は望遠端状態における無限遠合焦状態でのコマ収差図である。
また、図６６は、広角端状態における撮影倍率−１／３０倍でのコマ収差図であり、図６７は第１中間焦点距離状態における撮影倍率−１／３０倍でのコマ差図であり、図６８は第２中間焦点距離状態における撮影倍率−１／３０倍でのコマ収差図であり、図６９は望遠端状態における撮影倍率−１／３０倍でのコマ収差図である。
図６２乃至図６９の各収差図は、像高Ｙの正方向に接合正レンズＬ41を移動させたときのＹ＝１５．０，０，−１５．０でのコマ収差を示している。
【００８７】
各収差図において、ＦNOはＦナンバーを、ＮＡは開口数を、Ｙは像高を、Ａは各像高に対する半画角を、Ｈは各像高に対する物体高をそれぞれ示している。
また、非点収差を示す収差図において、実線はサジタル像面を示し、破線はメリディオナル像面を示している。さらに、球面収差を示す収差図において、破線はサインコンディション（正弦条件）を示している。
各収差図から明らかなように、本実施例では、各撮影距離状態および各焦点距離状態において像シフト時にも諸収差が良好に補正されていることがわかる。
【００８８】
【発明の効果】
以上説明したように、本発明によれば、小型で、高性能で、５倍程度の変倍比を有する高変倍化に適した像シフト可能な変倍光学系を実現することができる。なお、変倍光学系のレンズ群中に複数の非球面を導入することにより大口径化や高変倍化や小型化をさらに進めることができることはいうまでもない。
【図面の簡単な説明】
【図１】本発明の各実施例にかかる変倍光学系の屈折力配分および広角端状態（Ｗ）から望遠端状態（Ｔ）への変倍時における各レンズ群の移動の様子を示す図である。
【図２】本発明の第１実施例にかかる変倍光学系の構成を示す図である。
【図３】第１実施例の広角端状態における無限遠合焦状態での諸収差図である。
【図４】第１実施例の第１中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図５】第１実施例の第２中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図６】第１実施例の望遠端状態における無限遠合焦状態での諸収差図である。
【図７】第１実施例の広角端状態における撮影倍率−１／３０倍での諸収差図である。
【図８】第１実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図９】第１実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図１０】第１実施例の望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【図１１】第１実施例の広角端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図１２】第１実施例の第１中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図１３】第１実施例の第２中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図１４】第１実施例の望遠端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図１５】第１実施例の広角端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図１６】第１実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図１７】第１実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図１８】第１実施例の望遠端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図１９】本発明の第２実施例にかかる変倍光学系の構成を示す図である。
【図２０】第２実施例の広角端状態における無限遠合焦状態での諸収差図である。
【図２１】第２実施例の第１中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図２２】第２実施例の第２中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図２３】第２実施例の望遠端状態における無限遠合焦状態での諸収差図である。
【図２４】第２実施例の広角端状態における撮影倍率−１／３０倍での諸収差図である。
【図２５】第２実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図２６】第２実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図２７】第２実施例の望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【図２８】第２実施例の広角端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図２９】第２実施例の第１中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図３０】第２実施例の第２中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図３１】第２実施例の望遠端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図３２】第２実施例の広角端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図３３】第２実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図３４】第２実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図３５】第２実施例の望遠端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図３６】本発明の第３実施例にかかる変倍光学系の構成を示す図である。
【図３７】第３実施例の広角端状態における無限遠合焦状態での諸収差図である。
【図３８】第３実施例の第１中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図３９】第３実施例の第２中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図４０】第３実施例の望遠端状態における無限遠合焦状態での諸収差図である。
【図４１】第３実施例の広角端状態における撮影倍率−１／３０倍での諸収差図である。
【図４２】第３実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図４３】第３実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図４４】第３実施例の望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【図４５】第３実施例の広角端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図４６】第３実施例の第１中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図４７】第３実施例の第２中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図４８】第３実施例の望遠端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図４９】第３実施例の広角端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図５０】第３実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図５１】第３実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図５２】第３実施例の望遠端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図５３】本発明の第４実施例にかかる変倍光学系の構成を示す図である。
【図５４】第４実施例の広角端状態における無限遠合焦状態での諸収差図である。
【図５５】第４実施例の第１中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図５６】第４実施例の第２中間焦点距離状態における無限遠合焦状態での諸収差図である。
【図５７】第４実施例の望遠端状態における無限遠合焦状態での諸収差図である。
【図５８】第４実施例の広角端状態における撮影倍率−１／３０倍での諸収差図である。
【図５９】第４実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図６０】第４実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での諸収差図である。
【図６１】第４実施例の望遠端状態における撮影倍率−１／３０倍での諸収差図である。
【図６２】第４実施例の広角端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図６３】第４実施例の第１中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図６４】第４実施例の第２中間焦点距離状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図６５】第４実施例の望遠端状態における無限遠合焦状態での像シフト時のコマ収差図である。
【図６６】第４実施例の広角端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図６７】第４実施例の第１中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図６８】第４実施例の第２中間焦点距離状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【図６９】第４実施例の望遠端状態における撮影倍率−１／３０倍での像シフト時のコマ収差図である。
【符号の説明】
Ｇ１ 第１レンズ群
Ｇ２ 第２レンズ群
Ｇ３ 第３レンズ群
Ｇ４ 第４レンズ群
Ｇ５ 第５レンズ群
Ｌｉ 各レンズ成分
Ｓ 開口絞り[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable magnification optical system capable of shifting an image, and more particularly to a variable magnification optical system capable of shifting an image by moving some lens units in a direction substantially perpendicular to an optical axis.
[0002]
[Prior art]
In recent years, zoom lenses have become common in photographic optical systems used in still cameras, video cameras, and the like. In particular, cameras equipped with so-called high zoom zoom lenses with zoom ratios exceeding 3 times are becoming mainstream.
In this type of camera, a standard zoom lens (a zoom lens including an angle of view with a focal length of about 50 mm in a 35 mm format) is used. Note that a so-called multi-group zoom lens in which three or more lens groups move during zooming is mainly used as the high-magnification zoom lens.
In addition, in an integrated camera in which a photographing optical system and a camera body are integrally configured, portability is important, and thus reduction in size and weight is required. Therefore, various proposals regarding zoom lenses suitable for miniaturization and weight reduction have been made. In these zoom lenses, the focal length has been increased as the zoom ratio is increased.
[0003]
By the way, conventionally, when the shutter speed is slow, there has been a case where the image is unsatisfactory because the image is blurred during exposure due to camera shake caused by camera shake or the like.
In general, when a part of the lens groups constituting the lens system (hereinafter referred to as “shift lens group”) is moved in a direction perpendicular to the optical axis, the image is shifted in the direction perpendicular to the optical axis. It is known. In this case, an optical system capable of obtaining good imaging performance even when the shift lens group is moved in a direction perpendicular to the optical axis is called an optical system capable of image shift.
[0004]
In order to solve the problem of shooting failure caused by the above-mentioned camera shake or the like, an optical system capable of image shifting, a blur detection system for detecting blur of the optical system and outputting blur information, and a shift lens group are moved. A so-called anti-vibration optical system combined with a drive system is known. In the anti-vibration optical system, the shake detection system detects the blur of the optical system due to camera shake, etc., and shifts by the drive system so as to cancel the fluctuation of the image position caused by the detected blur of the optical system Image shift is performed by moving the lens group. In this way, in the image stabilization optical system, it is possible to correct the image position fluctuation, that is, the image blur caused by the blur of the optical system, by the intentionally generated image shift.
[0005]
[Problems to be solved by the invention]
However, it is difficult to hold the camera so as not to shake with a small and lightweight camera. Therefore, camera shake is likely to occur when the release button is pressed, and as a result, image blur is often recorded. In particular, in a photographic lens with a long focal length in order to increase the zoom ratio, remarkable image blur is likely to occur even with a minute amount of blur in the lens system, and photographing is likely to fail.
In this case, by incorporating an anti-vibration optical system in the camera, it is also possible to correct image position fluctuations caused by camera shake due to camera shake or the like. However, the anti-vibration optical system imposes excessive constraints on the correction of aberrations, leading to an increase in the entire lens system due to an increase in the overall lens length and the aperture diameter, and as a result, the portability of the camera body tends to deteriorate. .
[0006]
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a variable magnification optical system that is compact and can shift an image suitable for high magnification.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, a lens group Gs having a positive refractive power, a lens group Gn having a negative refractive power arranged adjacent to the object side of the lens group Gs, A lens group Ga disposed adjacent to the image side of the lens group Gs,
When the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the lens group Gn and the lens group Gs decreases, and the air gap between the lens group Gs and the lens group Ga changes.
The lens group Gs has at least two partial lens groups, and by moving one partial lens group Gh of the at least two partial lens groups in a direction substantially perpendicular to the optical axis, the lens group Gs is substantially perpendicular to the optical axis. Shift the image along any direction,
When the focal length of the lens group Gs is fs and the focal length of the partial lens group Gh is fh,
0.3 <fs / fh <0.6
An image shiftable variable magnification optical system characterized by satisfying the following conditions is provided.
[0008]
According to a preferred aspect of the present invention, an aperture stop S is provided in the lens group Gs or adjacent to the lens group Gs.
The lens group Ga has a negative refractive power,
When the lens position state changes from the wide-angle end state to the telephoto end state, the lens group Ga moves to the object side,
The lateral magnification of the lens group Ga in the wide-angle end state is β5w, the lateral magnification of the lens group Ga in the telephoto end state is β5t, the focal length of the entire optical system in the wide-angle end state is fw, and the optical system in the telephoto end state When the total focal length is ft,
0.4 <(β5t / β5w) / (ft / fw) <0.7
Satisfy the conditions.
[0009]
According to another aspect of the present invention, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power or a negative refractive power, and a negative A third lens group G3 having a refractive power; a fourth lens group G4 having a positive refractive power; and a fifth lens group G5 having a negative refractive power;
When the lens position state changes from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the second lens group G2 and the third lens group G3. The air gap between the third lens group G3 and the fourth lens group G4 decreases, and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. In addition, at least the first lens group G1 and the fifth lens group G5 move to the object side,
By moving a part of the fourth lens group G4 in a direction substantially perpendicular to the optical axis, the image is shifted along a direction substantially perpendicular to the optical axis,
The lateral magnification of the fifth lens group G5 in the wide-angle end state is β5w, the lateral magnification of the fifth lens group G5 in the telephoto end state is β5t, the focal length of the entire optical system in the wide-angle end state is fw, and the telephoto end When the focal length of the entire optical system in the state is ft,
0.4 <(β5t / β5w) / (ft / fw) <0.7
An image shiftable variable magnification optical system characterized by satisfying the following conditions is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, an image shift amount generated when a shift lens group including a part of lens groups in the optical system is moved in a direction perpendicular to the optical axis will be described.
Assuming that the lateral magnification of the shift lens group is βa and the lateral magnification of the entire lens group disposed on the image side of the shift lens group is βb, the image shift amount δ with respect to the shift lens group movement amount Δ is expressed by the following equation ( a).
δ = (1−βa) βb · Δ = k · Δ (a)
here,
k: blur coefficient (k = (1−βa) βb)
[0011]
When the blur coefficient k is small, the movement amount of the shift lens group necessary for shifting the image by a predetermined amount increases, and the drive mechanism of the shift lens group becomes complicated. On the other hand, when the blur coefficient k is large, if the movement amount of the shift lens group slightly varies due to a control error, the image shift amount largely varies and the contrast with respect to a high spatial frequency is lacking.
Therefore, it is desirable to set the blur coefficient k to an appropriate value.
[0012]
Next, the aberration correction function required for the shift lens group will be described.
Usually, the shift lens group is required to be in an aberration correction state so that good imaging performance can be obtained even during image shift. Specifically, (1) spherical aberration and sine condition (sine condition) are well corrected, and (2) an appropriate Petzval sum is required.
The spherical aberration and sine condition of (1) are well corrected is a condition for suppressing the decentration coma aberration that occurs at the center of the screen when the image is shifted by moving the shift lens group. Further, the appropriate Petzval sum of (2) is a condition for suppressing the curvature of field that occurs at the periphery of the screen when the image is shifted by moving the shift lens group.
[0013]
When the entire lens group of the plurality of lens groups constituting the zoom lens is a shift lens group, the aberration correction state required when the lens position state changes (ie, when zooming) and the performance during image shift The aberration correction state required to suppress the deterioration does not always match. Therefore, it is difficult to achieve both high zoom ratio and greater blur correction of the optical system.
In the present invention, one lens group is composed of a plurality of partial lens groups, and one partial lens group of the plurality of partial lens groups is used as a shift lens group. This makes it possible to achieve both blur correction.
[0014]
Further, when the shift lens group is disposed away from the aperture stop, the off-axis light beam passing through the shift lens group is separated from the optical axis. As a result, when the image is shifted, decentration coma tends to occur at the periphery of the screen. In particular, when an off-axis light beam incident on the shift lens group makes a large angle with respect to the optical axis, decentration coma is likely to occur at the periphery of the screen.
Therefore, it is desirable to appropriately set the positional relationship between the shift lens group and the aperture stop.
[0015]
As described above, in the zoom optical system according to the present invention, the performance is deteriorated due to the image shift while maintaining a predetermined zoom ratio by configuring so as to satisfy the following three conditions (1) to (3). Is suppressed.
(1) The refractive power of the lens group including the shift lens group is defined as a positive refractive power, and a negative lens group is disposed adjacent to the object side.
(2) An aperture stop is disposed between the shift lens group and the negative lens group.
(3) The change amount of the blur coefficient k when the lens position state changes from the wide-angle end state to the telephoto end state is set to an appropriate value.
[0016]
As described above, in order to correct the decentration coma generated in the peripheral portion of the screen due to the image shift, it is desirable to set the angle between the off-axis light beam incident on the shift lens group and the optical axis to an appropriate value. In the present invention, a negative lens group having a strong refractive power is disposed adjacent to the object side of the lens group including the shift lens group to strongly diverge the light beam emitted from the negative lens group, and at the image side of the negative lens group An aperture stop is arranged in With this configuration, high performance is realized by preventing the angle between the off-axis light beam incident on the shift lens group and the optical axis from increasing.
[0017]
In particular, in order to suppress performance deterioration during image shift, various aberrations need to be corrected satisfactorily by the shift lens group alone. Therefore, it is preferable that the refractive power of the shift lens group is a positive refractive power so that the aberration correction state of the shift lens group alone can be easily confirmed at the time of manufacture.
When the off-axis light beam that passes through the shift lens group is separated from the optical axis, the performance degradation at the periphery of the screen is large during image shift, and it is desirable to dispose the shift lens group in the vicinity of the aperture stop. In particular, in order to reduce the angle formed by the off-axis light beam incident on the shift lens group and the optical axis, a negative lens group is disposed on the object side of the aperture stop, and a shift lens group is disposed on the image side of the aperture stop. Is desirable.
From the above, the conditions (1) and (2) are important.
[0018]
As described above, the movement amount of the shift lens group necessary for shifting the image by a predetermined amount depends on the blur coefficient k. When the blur coefficient in the wide-angle end state and the focal length of the entire optical system are kw and fw, respectively, and the blur coefficient in the telephoto end state and the focal length of the entire optical system are kt and ft, respectively, the blur coefficient ratio K (= kt / When kw) is larger than the zoom ratio Z (= ft / fw), the lens position control accuracy required in the telephoto end state becomes extremely higher than the lens position control accuracy required in the wide-angle end state. Control becomes complicated. In addition, since the zooming operation is performed only by the lens group disposed on the image side of the shift lens group, the lens system can be reduced in size while suppressing fluctuations in various aberrations caused by changes in the lens position state. It becomes difficult.
[0019]
On the other hand, if the blur coefficient ratio K is very small compared to the zoom ratio Z, the zooming action is performed by the lens group disposed on the object side of the shift lens group, so that the total lens length is shortened and the lens diameter is reduced. The lens system cannot be downsized due to the downsizing of the lens.
Therefore, in the present invention, the blur coefficient ratio K is set to an appropriate value with respect to the zoom ratio Z, and both the performance degradation at the time of image shift is suppressed and the high zoom ratio is achieved. (3) is required.
[0020]
Next, a specific configuration of a variable magnification optical system that satisfies the above-described conditions (1) to (3) and is suitable for high magnification and lens system miniaturization will be described.
First, a general theory of a variable magnification optical system suitable for miniaturization of a lens system will be described.
It is known that the telephoto type refractive power arrangement is effective for reducing the size of the lens system. Therefore, in general, in a variable magnification optical system aimed at miniaturization, a negative lens group is arranged on the most image side of the lens system.
[0021]
The aperture stop is disposed on the object side with respect to the negative lens group. When the lens position changes from the wide-angle end state (the state with the shortest focal length) to the telephoto end state (the state with the longest focal length), (1) the interval between the aperture stop and the negative lens group is narrowed, And (2) the negative lens group is moved to the object side. By reducing the distance between the aperture stop and the negative lens group in (1), the off-axis light beam passing through the negative lens group is separated from the optical axis in the wide-angle end state, and approaches the optical axis in the telephoto end state. Further, by moving the negative lens group (2) to the object side, the negative lens group is multiplied (the lateral magnification of the negative lens group is increased in the telephoto end state compared to the wide-angle end state). . In this way, fluctuations in off-axis aberrations that occur with changes in the lens position state are corrected well, and a certain degree of high zooming is realized.
[0022]
However, if the back focus is too short in the wide-angle end state, the shadow of dust adhering to the surface of the negative lens group near the image plane will be reflected on the film surface, so the back focus in the wide-angle end state is set to an appropriate value. Yes.
Further, the positive lens unit is disposed closest to the object side of the variable magnification optical system, and the positive lens unit is brought closer to the image side in the wide-angle end state, thereby reducing the lens diameter of the positive lens unit. On the contrary, in the telephoto end state, the distance between the positive lens group and the lens group arranged on the image side is widened so that the positive lens group strongly converges the light beam, so that the total lens length is shortened to some extent.
[0023]
In general, zoom lenses are classified into a two-group type and a multi-group type. A two-group zoom lens composed only of a variator and a compensator is not suitable for high zooming. Therefore, a multi-group type is used for a high zoom lens having a zoom ratio exceeding 3 times.
As a specific configuration of a multi-group type zoom lens suitable for miniaturization and high zoom ratio, for example, (1) positive / negative / three-group type zoom lens, (2) positive / negative / positive / four-group type zoom lens, (3) There are known a positive / negative positive / negative 5 group type zoom lens, and a positive / negative negative positive / negative 5 group type zoom lens.
[0024]
In any of the multi-group type zoom lenses, as described above, the positive lens group is disposed closest to the object side of the lens system, the negative lens group is disposed closest to the image side, and the positive lens group is disposed between the positive lens group and the negative lens group. One positive lens group (in the case of (1)) or a plurality of lens groups (in the case of (2) to (4)) having a positive combined refractive power as a whole are arranged.
However, when the lens group moves in the optical axis direction by a minute amount, the image plane position moves in relation to the square of the lateral magnification. Therefore, in the case of the zoom lens of the type (1), when the zoom ratio becomes larger than 3 times, the lateral magnification of the negative lens group in the telephoto end state becomes very large, and a predetermined optical performance is ensured. difficult. In the zoom lenses of types (2) to (4), the combined focal length of the lens group disposed between the positive lens group and the negative lens group in the telephoto end state is significantly larger than in the wide-angle end state. Thus, since the composite principal point position moves to the object side, an increase in lateral magnification of the negative lens group in the telephoto end state is mitigated.
[0025]
In a typical configuration of the present invention, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a weak refractive power, a third lens group G3 having a negative refractive power, and a positive refraction. A variable power optical system is composed of the fourth lens group G4 having high power and the fifth lens group G5 having negative refractive power. When the lens position changes from the wide-angle end state to the telephoto end state, the distance between the first lens group G1 and the second lens group G2 increases, and the distance between the second lens group G2 and the third lens group G3. Increases, the distance between the third lens group G3 and the fourth lens group G4 decreases, and the distance between the fourth lens group G4 and the fifth lens group G5 decreases. The five lens group G5 is moved to the object side. A shift lens group is arranged in the fourth lens group G4. With the above configuration, the present invention can achieve a variable magnification optical system that is small in size and capable of image shifting with a variable magnification ratio exceeding 3.5 times.
[0026]
In particular, in the present invention, high performance and light weight are achieved by causing each lens group to function so as to satisfy the following conditions [I] to [III].
[I] The lateral magnification of the fifth lens group G5 in the telephoto end state is set to an appropriate value.
[II] The principal point position of the first lens group G1 and the principal point position of the second lens group G2 are set to appropriate positions.
[III] The aberration correction function of the second lens group G2 and the aberration correction function of the third lens group G3 are clarified.
[0027]
Similarly to the conventional multi-group type zoom lens, in the typical configuration of the present invention, the fifth lens group G5 having a negative refractive power is disposed closest to the image side. Then, when the lens position state changes from the wide-angle end state to the telephoto end state, the fifth lens group G5 moves to the object side.
If the lateral magnification of the fifth lens group G5 in the telephoto end state becomes too large, the change in the lateral magnification of the fifth lens group G5 from the wide-angle end state to the telephoto end state becomes large. As a result, fluctuations in off-axis aberration due to changes in the lens position state cannot be satisfactorily suppressed, and predetermined optical performance cannot be obtained.
[0028]
Conversely, if the lateral magnification of the fifth lens group G5 in the telephoto end state becomes too small, various aberrations that occur in the lens group disposed on the object side of the fifth lens group G5 due to a change in the lens position state. The fluctuations in the range become large, and the predetermined optical performance cannot be obtained. In either case, a predetermined optical performance can be ensured by using many aspheric surfaces or increasing the number of lenses, but it becomes impossible to achieve a reduction in cost and weight. Accordingly, it is desirable that the lateral magnification of the fifth lens group G5 in the telephoto end state is an appropriate value, and the condition [I] is required.
[0029]
In the wide-angle end state, since the back focus is short, positive distortion is strongly generated in the fifth lens group G5. In the present invention, the total focal length of the first lens group G1 to the third lens group G3 in the wide-angle end state is set to a negative value, thereby bringing the refractive power arrangement of the entire optical system closer to a symmetrical type and positive distortion. The aberration can be corrected satisfactorily.
In particular, in the present invention, the second lens group G2 is composed of a negative subgroup and a positive subgroup arranged on the image side thereof, so that the principal point position of the second lens group G2 (light flux is incident from the object side). The principal point position at the time of the exposure is positioned closer to the object side than the first lens group G1, and negative distortion can be effectively generated.
[0030]
In the telephoto end state, the principal point position of the first lens group G1 (the principal point position when the light beam is incident from the object side) is in the first lens group G1 or on the object side relative to the first lens group G1. By positioning the lens in the position, the overall length of the lens can be shortened. Therefore, it is desirable to dispose the positive lens on the most object side of the first lens group G1.
However, if the principal point position of the first lens group G1 is farther away from the object side than the first lens group G1, the off-axis light beam passing through the first lens group G1 in the telephoto end state is separated from the optical axis, and the lens diameter Will become larger.
From the above, the condition [II] is important.
[0031]
As described above, it is desirable to arrange the aperture stop in the vicinity of the fourth lens group G4 including the shift lens group. In this case, the off-axis light beam passes through the vicinity of the optical axis in the third lens group G3, whereas it passes through the peripheral edge portion in the second lens group G2. For this reason, the third lens group G3 corrects on-axis aberrations, and the second lens group G2 corrects off-axis aberrations, thereby configuring the second lens group G2 and the third lens group G3 with a small number of lenses. can do. As a result, it is possible to reduce the lens diameter by reducing the weight or reducing the lens thickness, so the condition [III] is important.
[0032]
Hereinafter, each conditional expression of the present invention will be described.
In the present invention, the following conditional expression (1) is satisfied.
0.3 <fs / fh <0.6 (1)
here,
fs: focal length of the lens group Gs including the shift lens group
fh: focal length of the partial lens group Gh which is a shift lens group
[0033]
Conditional expression (1) defines an appropriate range for the ratio of the focal length of the shift lens group Gh to the focal length of the lens group Gs including the shift lens group. This is a condition for suppressing the performance degradation at the time.
When the upper limit of conditional expression (1) is exceeded, the focal length of the shift lens group Gh increases, so that negative spherical aberration occurring in the shift lens group alone can be corrected well, and the shift is performed with a small number of lenses. A lens group can be configured. However, the number of lenses in other lens groups other than the shift lens group increases, making it impossible to achieve weight reduction.
On the other hand, if the lower limit of conditional expression (1) is not reached, the focal length of the shift lens group Gh becomes small, and it becomes difficult to satisfactorily correct negative spherical aberration that occurs in the shift lens group.
[0034]
In the present invention, in order to achieve high performance and light weight, it is desirable that the lens group Ga has negative refractive power and satisfies the following conditional expression (2).
0.4 <(β5t / β5w) / (ft / fw) <0.7
here,
β5w: Lateral magnification of the lens group Ga in the wide-angle end state
β5t: Lateral magnification of the lens group Ga in the telephoto end state
fw: focal length of the entire optical system in the wide-angle end state
ft: focal length of the entire optical system in the telephoto end state
[0035]
Conditional expression (2) defines a change in lateral magnification of the lens group Ga (that is, the fifth lens group G5 in a typical configuration) disposed on the image side of the lens group Gs including the shift lens group Gh.
Exceeding the upper limit value of conditional expression (2) is not preferable because the variation of off-axis aberration generated in the lens group Ga increases with the change of the lens position state, and high performance cannot be achieved. Further, the lateral magnification of the lens group Ga (fifth lens group G5) in the telephoto end state is increased, which is not preferable because the optical performance is easily deteriorated due to the focus shift due to the lens position control error.
On the other hand, if the lower limit value of conditional expression (2) is not reached, the zooming action by the lens group arranged on the object side with respect to the lens group Ga (fifth lens group G5) is increased. This is not preferable because each lens group to be configured cannot be configured with a small number of lenses.
[0036]
In the present invention, in order to shorten the total lens length in the telephoto end state and to reduce the size of the lens system, the first lens group G1 having a positive refractive power is provided closest to the object side, and the following conditions are satisfied. It is desirable to satisfy Formula (3).
0.8 <f1 / (fw · ft) ^1/2 <1.5 (3)
here,
f1: Focal length of the first lens group G1
[0037]
Exceeding the upper limit of conditional expression (3) is not preferable because the total lens length is increased.
Conversely, if the lower limit value of conditional expression (3) is not reached, the off-axis light beam passing through the first lens group G1 in the telephoto end state is separated from the optical axis, and the lens diameter of the first lens group G1 is increased. Therefore, it is not preferable.
[0038]
In the present invention, in order to shorten the total lens length in the telephoto end state while improving the optical performance in the wide-angle end state, the first lens group G1 and the lens group Gn are arranged. It is desirable to have two lens groups G2 and satisfy the following conditional expression (4).
−0.2 <fn / f2 <0.2 (4)
here,
f2: Focal length of the second lens group G2
fn: focal length of the lens group Gn
[0039]
Conditional expression (4) defines an appropriate range for the ratio between the focal length of the second lens group G2 and the focal length of the lens group Gn (that is, the third lens group G3 in a typical configuration).
If the upper limit value of conditional expression (4) is exceeded, the diverging action of the second lens group G2 becomes stronger, leading to an increase in the total lens length in the telephoto end state.
On the other hand, if the lower limit value of conditional expression (4) is not reached, the converging action of the second lens group G2 becomes stronger, and sufficient back focus cannot be obtained in the wide-angle end state.
[0040]
In the variable power optical system disclosed in Japanese Patent Laid-Open No. 7-92390, the diverging action by the second lens group G2 is strong. As a result, when increasing the zoom ratio by increasing the focal length of the entire optical system in the telephoto end state, it is difficult to shorten the entire lens length, which is insufficient in terms of miniaturization.
By the way, when moving a lens group arranged on the image side of the shift lens group as a focusing group and focusing on a close object, if the subject position changes, the lateral magnification of the shift lens group also changes from the shift lens group. In addition, the lateral magnification of the lens group disposed on the image side also changes. For this reason, in the present invention, it is desirable that the lens group disposed on the object side of the shift lens group is the focusing group.
[0041]
In particular, in the lens group far from the aperture stop S, the height at which the off-axis light beam passes away from the optical axis, the lens group Gn (third lens group G3) arranged in the vicinity of the aperture stop S is set as the focusing group. It is desirable. In this case, it is desirable that the following conditional expression (5) is satisfied.
0.2 <(β3t / β3w) / (ft / fw) <0.7 (5)
here,
β3w: lateral magnification of the lens group Gn in the wide-angle end state
β3t: Lateral magnification of the lens group Gn in the telephoto end state
[0042]
Conditional expression (5) defines a change in lateral magnification of the lens group Gn (third lens group G3) accompanying a change in the lens position state.
Generally, the depth of field in the telephoto end state is narrower than the depth of field in the wide-angle end state. Therefore, the lens position of the focusing group needs to be controlled with higher accuracy in the telephoto end state than in the wide-angle end state.
In the present invention, the amount of movement of the focusing group required to focus on a predetermined short-distance object from the infinitely focused state is increased in the telephoto end state than in the wide-angle end state, thereby The lens position control accuracy is prevented from becoming extremely high in the telephoto end state compared to the wide-angle end state.
[0043]
The amount of focusing movement (the amount that the focusing group moves when it is in focus) can be kept small when the lateral magnification of the focusing group is set to an appropriate value, as disclosed in JP-A-7-92390. In the present invention, it is desirable that the lateral magnification of the lens group Gn (third lens group G3) which is a focusing group is close to 0, but the lens group Gn (third lens group G3) in the telephoto end state compared to the wide-angle end state. The horizontal magnification of) is kept away from 0.
[0044]
When the upper limit value of conditional expression (5) is exceeded, the amount of focusing movement in the telephoto end state becomes large, and the driving mechanism for driving the focusing group becomes complicated.
On the other hand, if the lower limit of conditional expression (5) is not reached, the lens position control accuracy required to obtain the predetermined optical performance becomes higher in the telephoto end state than in the wide-angle end state, and the focusing group in the telephoto end state This is not preferable because the position where the optical system is focused changes greatly with respect to a minute amount of displacement.
[0045]
In the present invention, as described above, it is desirable to arrange the aperture stop S in the vicinity of the partial lens group Gh which is a shift lens group. In this case, it is desirable to satisfy the following conditional expression (6).
Db / fw <0.2 (6)
here,
Db: the distance along the optical axis between the aperture stop side surface of the partial lens group Gh which is a shift lens group and the aperture stop S
[0046]
When the upper limit of conditional expression (6) is exceeded, the difference in height between the on-axis light beam passing through the shift lens group and the off-axis light beam becomes large. As a result, unless the diameter of the shift lens group is increased, fluctuations in various aberrations that occur when an image is shifted by the shift lens group cannot be suppressed.
It should be noted that by configuring the shift lens group with a larger number of lenses, it is possible to suppress fluctuations in various aberrations during image shift. However, this is not preferable because not only the optical system is increased in size but also the drive mechanism for driving the shift lens group is complicated.
[0047]
Next, a method for correcting image position variation, that is, image blurring by the optical system will be described.
In general, when the optical system and the recording means for recording an image by the optical system are integrally tilted around the principal point position of the optical system (the principal point position when the light beam is incident from the object side), the recording means The recording range on the subject surface shifts while tilting.
Therefore, when the recording range before the optical system and the recording unit are integrally tilted is considered as a reference, the image in the recording range before the tilt is shifted while being tilted on the recording unit. However, when the image magnification is used as a reduction magnification, the amount of inclination of the image in the recording range before the inclination on the recording means is very small according to the Shine-proof law. Therefore, when applied to a camera or the like, it is considered that the image in the recording range before tilting shifts almost without tilting on the recording means.
[0048]
In general, the position of the subject image and the recording means are substantially the same, and it is considered that the subject image by the optical system is shifted when the optical system is shaken.
Assuming that the lens system rotates around the principal point position of the lens system, the variation amount (image blur amount) δ ′ of the image position with respect to the blur angle ε of the lens system is expressed by the following equation (b).
δ ′ = f · tan ε (b)
here,
f: Focal length of the entire lens system
[0049]
When the blur angle ε is relatively small, it can be approximated as tan ε≈ε, and the image position variation δ ′ is expressed by the following equation (c).
δ′≈f · ε (c)
When the image is recorded, if the variation amount δ ′ of the image position increases to some extent, it is recorded as an image blur.
[0050]
As the focal length of the optical system increases, the fluctuation amount δ ′ of the image position with respect to a predetermined blur angle ε of the optical system increases. Therefore, when the zoom ratio is increased and the focal length in the telephoto end state is increased, image blur is easily recorded due to blurring of the optical system due to camera shake or the like.
In order to correct the fluctuation of the image position due to the camera shake by offsetting the fluctuation amount δ ′ of the image position due to the camera shake or the like with the image shift amount δ due to the movement of the shift lens group, the relationship shown in the following equation (d) It is necessary to be established.
δ + δ ′ = 0 (d)
[0051]
When the above formulas (a) and (c) are substituted into formula (d), the relationship shown in the following formula (e) is obtained.
f · ε + kΔ = 0 (e)
That is, the shift amount Δ of the shift lens group necessary for correcting the fluctuation of the image position due to camera shake or the like is expressed by the following equation (f).
Δ = − (f / k) ε (f)
[0052]
Thus, based on the information about the blur angle ε of the optical system detected by the blur detection system, the information about the focal length of the optical system, and the information about the blur coefficient k, the required movement amount Δ of the shift lens group (that is, the image blur). By calculating the correction amount) and driving the shift lens group in the direction perpendicular to the optical axis by the required movement amount Δ by the drive system, it is possible to correct the fluctuation of the image position.
[0053]
As described above, according to the present invention, it is possible to achieve an image stabilization optical system that can correct fluctuations in image position caused by camera shake due to camera shake or the like. However, it goes without saying that the variable magnification optical system of the present invention is not only applicable to an optical system capable of image shifting, but also can achieve sufficiently high optical performance as a normal optical system. .
In each example described later, a part of the fourth lens group G4 is a shift lens group. However, the lens group including the shift lens group is not limited to the fourth lens group G4, and any lens group may be used. Also, a shift lens group can be provided.
[0054]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing the state of movement of each lens unit during refractive power distribution and zooming from the wide-angle end state (W) to the telephoto end state (T) according to each embodiment of the present invention. It is.
As shown in FIG. 1, the variable magnification optical system according to each embodiment of the present invention includes a first lens group G1 having a positive refractive power and a second lens having a positive or negative refractive power in order from the object side. It includes a group G2, a third lens group G3 having negative refractive power, a fourth lens group G4 having positive refractive power, and a fifth lens group G5 having negative refractive power. When zooming from the wide-angle end state to the telephoto end state, the air gap between the first lens group G1 and the second lens group G2 increases, and the air gap between the second lens group G2 and the third lens group G3 is Each lens group is moved to the object side so that the air gap between the third lens group G3 and the fourth lens group G4 decreases and the air gap between the fourth lens group G4 and the fifth lens group G5 decreases. Has moved.
[0055]
In each embodiment, the aspherical surface has a height in the direction perpendicular to the optical axis as y, a displacement amount (sag amount) in the optical axis direction at the height y as S (y), a reference radius of curvature as R, and a cone coefficient. Is represented by the following formula (g), where κ is κ and the n-th order aspherical coefficient is Cn.
[Expression 1]

In each embodiment, the aspherical surface is marked with * on the right side of the surface number.
[0056]
[First embodiment]
FIG. 2 is a diagram showing the configuration of the variable magnification optical system according to the first example of the present invention.
In the variable magnification optical system of FIG. 2, the first lens group G1 is composed of, in order from the object side, a cemented positive lens L1 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
The second lens group G2 includes a biconcave lens L21 and a biconvex lens L22 in order from the object side.
Further, the third lens group G3 is composed of a biconcave lens L3.
[0057]
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, and a cemented positive lens L42 including a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
Furthermore, the fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 having a concave surface directed toward the object side, a biconcave lens L52, and a negative meniscus lens L53 having a concave surface directed toward the object side.
[0058]
The aperture stop S is disposed between the third lens group G3 and the fourth lens group G4, and moves integrally with the fourth lens group G4 upon zooming from the wide-angle end state to the telephoto end state.
FIG. 2 shows the positional relationship of each lens group in the wide-angle end state. When zooming to the telephoto end state, the lens unit moves on the optical axis along the zoom orbit indicated by the arrow in FIG.
In addition, among the two lens components constituting the fourth lens group G4, the cemented positive lens L42 is moved in a direction substantially perpendicular to the optical axis to shift the image, thereby correcting the fluctuation of the image position caused by camera shake or the like. Yes. That is, the cemented positive lens L42 constitutes a partial lens group Gh that is a shift lens group.
Further, focusing is performed by moving the third lens group G3 along the optical axis.
[0059]
The following table (1) lists the values of the specifications of the first embodiment of the present invention. In Table (1), f is the focal length, FNO is the F number, ω is the half field angle, Bf is the back focus, and D0 is the distance along the optical axis between the object and the surface closest to the object. Represents. Further, the surface number indicates the order of the lens surfaces from the object side along the direction in which the light beam travels, and the refractive index and the Abbe number indicate values for the d-line (λ = 587.6 nm), respectively.
[0060]
[Table 1]

[0061]
3 to 10 are graphs showing various aberrations of the first example with respect to the d-line (λ = 587.6 nm). FIG. 3 is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state (shortest focal length state), and FIG. 4 is a diagram illustrating various aberrations in the infinitely focused state in the first intermediate focal length state. FIG. 5 is a diagram of various aberrations in the infinitely focused state in the second intermediate focal length state, and FIG. 6 is a diagram of various aberrations in the infinitely focused state in the telephoto end state (longest focal length state).
7 is a diagram showing various aberrations at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 8 is a diagram showing various aberrations at a photographing magnification of −1/30 times in the first intermediate focal length state. 9 is a diagram of various aberrations at a photographing magnification of −1/30 times in the second intermediate focal length state, and FIG. 10 is a diagram of various aberrations at a photographing magnification of −1/30 times in the telephoto end state.
[0062]
Further, FIGS. 11 to 18 are coma aberration diagrams when the image is shifted by 0.01 rad (radian) with respect to the optical axis in the first embodiment. 11 is a coma aberration diagram in the infinite focus state in the wide-angle end state, FIG. 12 is a coma aberration diagram in the infinite focus state in the first intermediate focal length state, and FIG. FIG. 14 is a coma aberration diagram in the infinite focus state in the telephoto end state, and FIG. 14 is a coma aberration diagram in the infinite focus state in the telephoto end state.
FIG. 15 is a coma aberration diagram at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 16 is a coma difference diagram at a photographing magnification of −1/30 times in the first intermediate focal length state. FIG. 17 is a coma aberration diagram at an imaging magnification of −1/30 times in the second intermediate focal length state, and FIG. 18 is a coma aberration diagram at an imaging magnification of −1/30 times in the telephoto end state.
11 to 18 show coma aberrations when Y = 15.0, 0, and -15.0 when the cemented positive lens L42 is moved in the positive direction of the image height Y. FIG.
[0063]
In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, Y represents an image height, A represents a half angle of view for each image height, and H represents an object height for each image height.
In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. Further, in the aberration diagram showing the spherical aberration, the broken line indicates the sine condition (sine condition).
As is apparent from the respective aberration diagrams, in this embodiment, it is understood that various aberrations are well corrected even during image shift in each shooting distance state and each focal length state.
[0064]
[Second Embodiment]
FIG. 19 is a diagram showing a configuration of a variable magnification optical system according to the second example of the present invention.
In the variable magnification optical system of FIG. 19, the first lens group G1 is composed of, in order from the object side, a cemented positive lens L1 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
The second lens group G2 includes a biconcave lens L21 and a biconvex lens L22 in order from the object side.
Further, the third lens group G3 is composed of a biconcave lens L3.
[0065]
The fourth lens group G4 includes, in order from the object side, a biconvex lens L41, and a cemented positive lens L42 including a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
Further, the fifth lens group G5 includes, in order from the object side, a biconvex lens L51, a biconcave lens L52, and a negative meniscus lens L53 having a concave surface directed toward the object side.
[0066]
The aperture stop S is disposed in the fourth lens group G4 and moves integrally with the fourth lens group G4 upon zooming from the wide-angle end state to the telephoto end state.
FIG. 19 shows the positional relationship of each lens group in the wide-angle end state. When zooming to the telephoto end state, the lens unit moves on the optical axis along the zoom orbit indicated by the arrow in FIG.
In addition, among the two lens components constituting the fourth lens group G4, the cemented positive lens L42 is moved in a direction substantially perpendicular to the optical axis to shift the image, thereby correcting the fluctuation of the image position caused by camera shake or the like. Yes. That is, the cemented positive lens L42 constitutes a partial lens group Gh that is a shift lens group.
Further, focusing is performed by moving the third lens group G3 along the optical axis.
[0067]
The following table (2) lists values of specifications of the second embodiment of the present invention. In Table (2), f is the focal length, FNO is the F number, ω is the half field angle, Bf is the back focus, and D0 is the distance along the optical axis between the object and the surface closest to the object. Represents. Further, the surface number indicates the order of the lens surfaces from the object side along the direction in which the light beam travels, and the refractive index and the Abbe number indicate values for the d-line (λ = 587.6 nm), respectively.
[0068]
[Table 2]

[0069]
20 to 27 are graphs showing various aberrations of the second example with respect to the d-line (λ = 587.6 nm). FIG. 20 is a diagram of various aberrations in the infinite focus state in the wide-angle end state, FIG. 21 is a diagram of various aberrations in the infinite focus state in the first intermediate focal length state, and FIG. 22 is the second intermediate focus. FIG. 23 is a diagram illustrating various aberrations in the infinite focus state in the telephoto end state, and FIG. 23 is a diagram illustrating various aberrations in the infinite focus state in the telephoto end state.
FIG. 24 is a diagram of various aberrations at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 25 is a diagram of various aberrations at a photographing magnification of −1/30 times in the first intermediate focal length state. FIG. 26 is a diagram of various aberrations at a photographing magnification of −1/30 times in the second intermediate focal length state, and FIG. 27 is a diagram of various aberrations at a photographing magnification of −1/30 times in the telephoto end state.
[0070]
Further, FIGS. 28 to 35 are coma aberration diagrams when the image is shifted by 0.01 rad (radian) with respect to the optical axis in the second embodiment. 28 is a coma aberration diagram in the infinite focus state in the wide-angle end state, FIG. 29 is a coma aberration diagram in the infinite focus state in the first intermediate focal length state, and FIG. 30 is the second intermediate focus state. FIG. 31 is a coma aberration diagram in the infinite focus state in the telephoto end state, and FIG. 31 is a coma aberration diagram in the infinite focus state in the telephoto end state.
FIG. 32 is a coma aberration diagram at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 33 is a coma difference diagram at a photographing magnification of −1/30 times in the first intermediate focal length state. FIG. 34 is a coma aberration diagram at an imaging magnification of −1/30 in the second intermediate focal length state, and FIG. 35 is a coma aberration diagram at an imaging magnification of −1/30 in the telephoto end state.
The aberration diagrams in FIGS. 28 to 35 show coma aberration at Y = 15.0, 0, and −15.0 when the cemented positive lens L42 is moved in the positive direction of the image height Y.
[0071]
In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, Y represents an image height, A represents a half angle of view for each image height, and H represents an object height for each image height.
In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. Further, in the aberration diagram showing the spherical aberration, the broken line indicates the sine condition (sine condition).
As is apparent from the respective aberration diagrams, in this embodiment, it is understood that various aberrations are well corrected even during image shift in each shooting distance state and each focal length state.
[0072]
[Third embodiment]
FIG. 36 is a diagram showing a configuration of a variable magnification optical system according to the third example of the present invention.
36, the first lens group G1 includes, in order from the object side, a cemented positive lens L1 including a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
The second lens group G2 includes a biconcave lens L21 and a biconvex lens L22 in order from the object side.
Further, the third lens group G3 is composed of a biconcave lens L3.
[0073]
The fourth lens group G4 includes, in order from the object side, a cemented positive lens L41 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side, and a biconvex lens L42.
Furthermore, the fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 having a concave surface directed toward the object side, a biconcave lens L52, and a negative meniscus lens L53 having a concave surface directed toward the object side.
[0074]
The aperture stop S is disposed between the third lens group G3 and the fourth lens group G4, and moves integrally with the fourth lens group G4 upon zooming from the wide-angle end state to the telephoto end state.
FIG. 36 shows the positional relationship of each lens group in the wide-angle end state. When zooming to the telephoto end state, the lens unit moves on the optical axis along the zoom orbit indicated by the arrow in FIG.
In addition, among the two lens components constituting the fourth lens group G4, the cemented positive lens L41 is moved in a direction substantially perpendicular to the optical axis to perform image shift, thereby correcting the image position variation caused by camera shake or the like. Yes. That is, the cemented positive lens L41 constitutes a partial lens group Gh that is a shift lens group.
Further, focusing is performed by moving the third lens group G3 along the optical axis.
[0075]
The following table (3) lists the values of the specifications of the third embodiment of the present invention. In Table (3), f is the focal length, FNO is the F number, ω is the half field angle, Bf is the back focus, and D0 is the distance along the optical axis between the object and the surface closest to the object. Represents. Further, the surface number indicates the order of the lens surfaces from the object side along the direction in which the light beam travels, and the refractive index and the Abbe number indicate values for the d-line (λ = 587.6 nm), respectively.
[0076]
[Table 3]

[0077]
37 to 44 are graphs showing various aberrations of the third example with respect to the d-line (λ = 587.6 nm). FIG. 37 is a diagram of various aberrations in the infinite focus state in the wide-angle end state, FIG. 38 is a diagram of various aberrations in the infinite focus state in the first intermediate focal length state, and FIG. 39 is the second intermediate focus. FIG. 40 is a diagram of various aberrations in the infinite focus state in the telephoto end state, and FIG. 40 is a diagram of various aberrations in the infinite focus state in the telephoto end state.
41 is a diagram of various aberrations at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 42 is a diagram of various aberrations at a photographing magnification of −1/30 times in the first intermediate focal length state. 43 is a diagram of various aberrations at a photographing magnification of −1/30 times in the second intermediate focal length state, and FIG. 44 is a diagram of various aberrations at a photographing magnification of −1/30 times in the telephoto end state.
[0078]
45 to 52 are coma aberration diagrams when the image is shifted by 0.01 rad (radian) with respect to the optical axis in the third embodiment. FIG. 45 is a coma aberration diagram in the infinite focus state in the wide-angle end state, FIG. 46 is a coma aberration diagram in the infinite focus state in the first intermediate focal length state, and FIG. 47 is the second intermediate focus state. FIG. 48 is a coma aberration diagram in the infinite focus state in the telephoto end state, and FIG. 48 is a coma aberration diagram in the infinite focus state in the telephoto end state.
FIG. 49 is a coma aberration diagram at a shooting magnification of −1/30 times in the wide-angle end state, and FIG. 50 is a coma difference diagram at a shooting magnification of −1/30 times in the first intermediate focal length state. FIG. 51 is a coma aberration diagram at an imaging magnification of −1/30 times in the second intermediate focal length state, and FIG. 52 is a coma aberration diagram at an imaging magnification of −1/30 times in the telephoto end state.
45 to 52 show coma aberrations at Y = 15.0, 0, and −15.0 when the cemented positive lens L41 is moved in the positive direction of the image height Y.
[0079]
In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, Y represents an image height, A represents a half angle of view for each image height, and H represents an object height for each image height.
In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. Further, in the aberration diagram showing the spherical aberration, the broken line indicates the sine condition (sine condition).
As is apparent from the respective aberration diagrams, in this embodiment, it is understood that various aberrations are well corrected even during image shift in each shooting distance state and each focal length state.
[0080]
[Fourth embodiment]
FIG. 53 is a diagram showing a configuration of a variable magnification optical system according to the fourth example of the present invention.
In the variable magnification optical system of FIG. 53, the first lens group G1 includes, in order from the object side, a cemented positive lens L1 composed of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.
The second lens group G2 includes a biconcave lens L21 and a biconvex lens L22 in order from the object side.
Further, the third lens group G3 is composed of a biconcave lens L3.
[0081]
The fourth lens group G4 includes, in order from the object side, a cemented positive lens L41 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side, and a biconvex lens L42.
Furthermore, the fifth lens group G5 includes, in order from the object side, a positive meniscus lens L51 having a concave surface directed toward the object side, a biconcave lens L52, and a negative meniscus lens L53 having a concave surface directed toward the object side.
[0082]
The aperture stop S is disposed between the third lens group G3 and the fourth lens group G4, and moves integrally with the fourth lens group G4 upon zooming from the wide-angle end state to the telephoto end state.
FIG. 53 shows the positional relationship of each lens group in the wide-angle end state. When zooming to the telephoto end state, the lens unit moves on the optical axis along the zoom orbit indicated by the arrow in FIG.
In addition, among the two lens components constituting the fourth lens group G4, the cemented positive lens L41 is moved in a direction substantially perpendicular to the optical axis to perform image shift, thereby correcting the image position variation caused by camera shake or the like. Yes. That is, the cemented positive lens L41 constitutes a partial lens group Gh that is a shift lens group.
Further, focusing is performed by moving the third lens group G3 along the optical axis.
[0083]
In the following table (4), values of specifications of the fourth embodiment of the present invention are listed. In Table (4), f is the focal length, FNO is the F number, ω is the half field angle, Bf is the back focus, and D0 is the distance along the optical axis between the object and the surface closest to the object. Represents. Further, the surface number indicates the order of the lens surfaces from the object side along the direction in which the light beam travels, and the refractive index and the Abbe number indicate values for the d-line (λ = 587.6 nm), respectively.
[0084]
[Table 4]

[0085]
54 to 61 are graphs showing various aberrations of the fourth example with respect to the d-line (λ = 587.6 nm). FIG. 54 is a diagram showing various aberrations in the infinite focus state in the wide-angle end state, FIG. 55 is a diagram showing various aberrations in the infinite focus state in the first intermediate focal length state, and FIG. 56 is the second intermediate focus. FIG. 57 is a diagram of various aberrations in the infinity focus state in the distance state, and FIG. 57 is a diagram of various aberrations in the infinity focus state in the telephoto end state.
58 is a diagram of various aberrations at a photographing magnification of −1/30 times in the wide-angle end state, and FIG. 59 is a diagram of various aberrations at a photographing magnification of −1/30 times in the first intermediate focal length state. 60 is a diagram of various aberrations at a photographing magnification of −1/30 times in the second intermediate focal length state, and FIG. 61 is a diagram of various aberrations at a photographing magnification of −1/30 times in the telephoto end state.
[0086]
Further, FIGS. 62 to 69 are coma aberration diagrams when the image is shifted by 0.01 rad (radian) with respect to the optical axis in the fourth embodiment. 62 is a coma aberration diagram in the infinitely focused state in the wide-angle end state, FIG. 63 is a coma aberration diagram in the infinitely focused state in the first intermediate focal length state, and FIG. 64 is the second intermediate lens. FIG. 65 is a coma aberration diagram in the infinite focus state in the telephoto end state, and FIG. 65 is a coma aberration diagram in the infinite focus state in the telephoto end state.
66 is a coma aberration diagram at an imaging magnification of 1/30 times in the wide-angle end state, and FIG. 67 is a coma difference diagram at an imaging magnification of 1/30 times in the first intermediate focal length state. 68 is a coma aberration diagram at an imaging magnification of −1/30 times in the second intermediate focal length state, and FIG. 69 is a coma aberration diagram at an imaging magnification of −1/30 times in the telephoto end state.
62 to 69 show coma aberrations at Y = 15.0, 0, and −15.0 when the cemented positive lens L41 is moved in the positive direction of the image height Y.
[0087]
In each aberration diagram, FNO represents an F number, NA represents a numerical aperture, Y represents an image height, A represents a half angle of view for each image height, and H represents an object height for each image height.
In the aberration diagrams showing astigmatism, the solid line shows the sagittal image plane, and the broken line shows the meridional image plane. Further, in the aberration diagram showing the spherical aberration, the broken line indicates the sine condition (sine condition).
As is apparent from the respective aberration diagrams, in this embodiment, it is understood that various aberrations are well corrected even during image shift in each shooting distance state and each focal length state.
[0088]
【The invention's effect】
As described above, according to the present invention, it is possible to realize a variable-magnification optical system that is compact, high-performance, and capable of image shifting suitable for high zooming having a zooming ratio of about 5 times. Needless to say, the introduction of a plurality of aspheric surfaces in the lens group of the variable magnification optical system can further increase the diameter, increase the magnification, and reduce the size.
[Brief description of the drawings]
FIG. 1 is a diagram showing a state of movement of each lens unit during refractive power distribution and zooming from a wide-angle end state (W) to a telephoto end state (T) of a zoom optical system according to each embodiment of the present invention. It is.
FIG. 2 is a diagram showing a configuration of a variable magnification optical system according to the first example of the present invention.
FIG. 3 is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state according to the first example.
FIG. 4 is a diagram illustrating various aberrations in the infinitely focused state in the first intermediate focal length state according to the first example.
FIG. 5 is a diagram illustrating various aberrations in the infinitely focused state in the second intermediate focal length state according to the first example.
FIG. 6 is a diagram illustrating various aberrations in the infinite focus state in the telephoto end state according to the first embodiment.
FIG. 7 is a diagram illustrating all aberrations at the photographing magnification of −1 / 30 × in the wide-angle end state according to the first example.
FIG. 8 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the first intermediate focal length state according to the first example.
FIG. 9 is a diagram illustrating various aberrations at the imaging magnification of −1/30 in the second intermediate focal length state according to the first example.
FIG. 10 is a diagram illustrating various aberrations at the photographing magnification of −1/30 in the telephoto end state of the first example.
FIG. 11 is a coma aberration diagram during image shift in the infinitely focused state at the wide-angle end state in the first example.
12 is a coma aberration diagram during image shift in the infinitely focused state at the first intermediate focal length state according to the first example. FIG.
FIG. 13 is a coma aberration diagram during image shift in the infinitely focused state at the second intermediate focal length state in the first example.
FIG. 14 is a coma aberration diagram during image shift in the infinite focus state in the telephoto end state according to the first example.
FIG. 15 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the wide-angle end state according to the first example.
FIG. 16 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the first intermediate focal length state according to the first example.
FIG. 17 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the second intermediate focal length state according to the first example.
FIG. 18 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the telephoto end state according to the first embodiment.
FIG. 19 is a diagram showing a configuration of a variable magnification optical system according to the second example of the present invention.
FIG. 20 is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state according to the second example.
FIG. 21 is a diagram illustrating various aberrations in the infinitely focused state in the first intermediate focal length state according to the second example.
FIG. 22 is a diagram illustrating various aberrations in the infinitely focused state in the second intermediate focal length state according to the second example.
FIG. 23 is a diagram illustrating various aberrations in the infinitely focused state in the telephoto end state according to the second embodiment.
FIG. 24 is a diagram illustrating all aberrations at the photographing magnification of −1 / 30 × in the wide-angle end state according to the second example.
FIG. 25 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the first intermediate focal length state according to the second example.
FIG. 26 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the second intermediate focal length state according to the second example.
FIG. 27 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the telephoto end state of the second example.
FIG. 28 is a coma aberration diagram during image shift in the infinitely focused state at the wide-angle end state in the second example.
FIG. 29 is a coma aberration diagram during image shift in the infinitely focused state at the first intermediate focal length state according to the second example.
FIG. 30 is a coma aberration diagram during image shift in the infinitely focused state at the second intermediate focal length state according to the second example.
FIG. 31 is a coma aberration diagram during image shift in the infinite focus state in the telephoto end state according to the second embodiment.
32 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the wide-angle end state according to Example 2. FIG.
FIG. 33 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the first intermediate focal length state according to the second example.
FIG. 34 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the second intermediate focal length state according to the second example.
FIG. 35 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the telephoto end state according to the second embodiment.
FIG. 36 is a diagram showing a configuration of a variable magnification optical system according to the third example of the present invention.
FIG. 37 is a diagram illustrating various aberrations in the infinitely focused state at the wide-angle end state in the third example.
FIG. 38 is a diagram illustrating various aberrations in the infinitely focused state in the first intermediate focal length state according to the third example.
FIG. 39 is a diagram illustrating various aberrations in the infinitely focused state in the second intermediate focal length state according to the third example.
FIG. 40 is a diagram illustrating various aberrations in the infinitely focused state in the telephoto end state according to the third example.
FIG. 41 is a diagram illustrating all aberrations at the shooting magnification of −1/30 in the wide-angle end state according to the third example.
FIG. 42 is a diagram illustrating various aberrations at the imaging magnification of −1/30 in the first intermediate focal length state according to the third example.
FIG. 43 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the second intermediate focal length state according to the third example.
FIG. 44 is a diagram illustrating all aberrations at the photographing magnification of −1/30 in the telephoto end state according to the third example.
FIG. 45 is a coma aberration diagram during image shift in the infinitely focused state at the wide-angle end state in the third example.
FIG. 46 is a coma aberration diagram during image shift in the infinitely focused state at the first intermediate focal length state according to the third example.
FIG. 47 is a coma aberration diagram during image shift in the infinitely focused state at the second intermediate focal length state according to the third example.
FIG. 48 is a coma aberration diagram during image shift in the infinitely focused state at the telephoto end state according to the third embodiment.
FIG. 49 is a coma aberration diagram during image shift at a shooting magnification of −1/30 in the wide-angle end state according to the third example.
FIG. 50 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the first intermediate focal length state according to the third example.
FIG. 51 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the second intermediate focal length state according to the third example.
FIG. 52 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the telephoto end state according to the third example.
FIG. 53 is a diagram showing a configuration of a variable magnification optical system according to the fourth example of the present invention.
FIG. 54 is a diagram illustrating various aberrations in the infinitely focused state in the wide-angle end state according to the fourth embodiment.
FIG. 55 is a diagram illustrating various aberrations in the infinitely focused state in the first intermediate focal length state according to the fourth embodiment.
FIG. 56 is a diagram illustrating various aberrations in the infinitely focused state in the second intermediate focal length state according to the fourth embodiment.
FIG. 57 is a diagram illustrating various aberrations in the infinitely focused state in the telephoto end state according to the fourth embodiment.
FIG. 58 is a diagram illustrating all aberrations at the photographing magnification of −1/30 times in the wide-angle end state according to the fourth example.
FIG. 59 is a diagram illustrating various aberrations at the imaging magnification of −1/30 in the first intermediate focal length state according to the fourth example.
FIG. 60 is a diagram illustrating all aberrations at the shooting magnification of −1/30 in the second intermediate focal length state according to the fourth example.
FIG. 61 is a diagram illustrating all aberrations at the photographing magnification of −1 / 30 × in the telephoto end state according to the fourth embodiment.
FIG. 62 is a coma aberration diagram during image shift in the infinitely focused state at the wide-angle end state in the fourth example.
FIG. 63 is a coma aberration diagram during image shift in the infinitely focused state at the first intermediate focal length state according to the fourth example.
FIG. 64 is a coma aberration diagram during image shift in the infinitely focused state at the second intermediate focal length state according to the fourth example.
FIG. 65 is a coma aberration diagram during image shift in the infinitely focused state at the telephoto end state according to the fourth embodiment.
66 is a coma aberration diagram during image shift at a shooting magnification of −1/30 in the wide-angle end state according to Example 4. FIG.
FIG. 67 is a coma aberration diagram during image shift at a shooting magnification of −1/30 in the first intermediate focal length state according to the fourth embodiment.
FIG. 68 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the second intermediate focal length state according to the fourth embodiment.
FIG. 69 is a coma aberration diagram during image shift at a photographing magnification of −1/30 in the telephoto end state according to the fourth embodiment.
[Explanation of symbols]
G1 first lens group
G2 second lens group
G3 Third lens group
G4 4th lens group
G5 5th lens group
Li Each lens component
S Aperture stop

Claims (8)

A lens group Gs having a positive refractive power, a lens group Gn having a negative refractive power disposed adjacent to the object side of the lens group Gs, and an image side of the lens group Gs. A lens group Ga;
When the lens position changes from the wide-angle end state to the telephoto end state, the air gap between the lens group Gn and the lens group Gs decreases, and the air gap between the lens group Gs and the lens group Ga changes.
The lens group Gs has at least two partial lens groups, and by moving one partial lens group Gh of the at least two partial lens groups in a direction substantially perpendicular to the optical axis, the lens group Gs is substantially perpendicular to the optical axis. Shift the image along any direction,
When the focal length of the lens group Gs is fs and the focal length of the partial lens group Gh is fh,
0.3 <fs / fh <0.6
An image-shiftable variable magnification optical system characterized by satisfying the following conditions:   2. The variable-magnification optical system capable of shifting an image according to claim 1, wherein an aperture stop S is provided in the lens group Gs or adjacent to the lens group Gs. The lens group Ga has a negative refractive power,
When the lens position state changes from the wide-angle end state to the telephoto end state, the lens group Ga moves to the object side,
The lateral magnification of the lens group Ga in the wide-angle end state is β5w, the lateral magnification of the lens group Ga in the telephoto end state is β5t, the focal length of the entire optical system in the wide-angle end state is fw, and the optical system in the telephoto end state When the total focal length is ft,
0.4 <(β5t / β5w) / (ft / fw) <0.7
3. The variable-magnification optical system capable of shifting an image according to claim 1, wherein the following condition is satisfied. A first lens group G1 having a positive refractive power disposed on the most object side;
When the focal length of the first lens group G1 is f1, the focal length of the entire optical system in the wide-angle end state is fw, and the focal length of the entire optical system in the telephoto end state is ft.
0.8 <f1 / (fw · ft) ^1/2 <1.5
The image-shiftable variable magnification optical system according to any one of claims 1 to 3, wherein the following condition is satisfied. When the lens position changes from the wide-angle end state to the telephoto end state, the first lens group G1 moves to the object side,
A second lens group G2 disposed between the first lens group G1 and the lens group Gn;
When the focal length of the second lens group G2 is f2, and the focal length of the lens group Gn is fn,
−0.2 <fn / f2 <0.2
5. The variable-magnification optical system capable of shifting an image according to claim 4, wherein the following condition is satisfied.   2. The focusing on a short-distance object is performed by moving one of the lens groups arranged on the object side of the lens group Gs along the optical axis. 6. A variable magnification optical system capable of shifting an image according to any one of 5 above. By moving the lens group Gn along the optical axis, focusing on a short-distance object,
The lateral magnification of the lens group Gn in the wide-angle end state is β3w, the lateral magnification of the lens group Gn in the telephoto end state is β3t, the focal length of the entire optical system in the wide-angle end state is fw, and the optical system in the telephoto end state When the total focal length is ft,
0.2 <(β3t / β3w) / (ft / fw) <0.7
The image-shiftable variable magnification optical system according to claim 1, wherein the following condition is satisfied. When the distance along the optical axis between the surface of the partial lens group Gh closest to the aperture stop and the aperture stop S is Db, and the focal length of the entire optical system in the wide-angle end state is fw,
Db / fw <0.2
The image-shiftable variable magnification optical system according to any one of claims 2 to 7, wherein the following condition is satisfied.

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