JP2004286811A - Zoom lens, camera, and mobile information terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a high capacity regardless of a zoom lens sufficiently miniaturized and having a wide angle of view and to obtain a resolution corresponding to an imaging device having 2,000,000 to 5,000,000 pixels. <P>SOLUTION: The zoom lens is so constituted that a first positive lens group G1, a second negative lens group G2, a third positive lens group G3, and a fourth positive lens group G4 are arranged in order from the object side toward the image surface side. The zoom lens has the second lens group G2 moved from the object side to the image surface side and has the third lens group G3 moved from the image surface side to the object side, in accordance with magnification varying from a wide angle end to a telephoto end. The third lens group includes a triple cemented lens having a negative lens E8, a positive lens E9, and a negative lens E10 joined to one another and has a positive lens E7 and a positive lens E11 on both sides of the triple cemented lens. A surface on the most object side of the second lens group G2, a surface on the most object side of the third lens group G3, and a surface on the most object side of the fourth lens group G4 are formed into aspherical surfaces. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３７】
〔第１の実施例〕
図１は、本発明の第１の実施例に係るズームレンズの光学系の構成を示している。
図１に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図１には、参考のために各光学面の面番号の一部も付して示している。なお、図１に対する各参照符号は、参照符号の桁数の増大による説明の煩雑化を避けるため、各実施例毎に独立に用いており、そのため共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００３８】
図１において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および光学フィルタＯＦの順で配列されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。
【００３９】
第７レンズＥ７は、両凸レンズからなる正レンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、物体側に凸に形成された正メニスカスレンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。第４レンズ群Ｇ４である第１２レンズＥ１２の像面側に配置された光学フィルタＯＦは、第４レンズ群Ｇ４と一体的に保持され、各種の光学フィルタリング機能を有する。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
【００４０】
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動する。
この第１の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜１７．３，Ｆ＝２．７１〜３．８８，ω＝４０．９８〜１４．６５の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００４１】
【表１】
光学特性

【００４２】
表１において「（非球面）」と記した第６面、第１２面、および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝１．１２０５２×１０^−４
Ａ_６＝−８．１０４７７×１０^−７
Ａ_８＝４．６２４７０×１０^−５
Ａ_１０＝−１．５４１３２×１０^−１１
非球面：第１２面
Ｋ＝０
Ａ_４＝−７．３５９９５×１０^−５
Ａ_６＝７．３４７７４×１０^−８
Ａ_８＝−６．３７３９５×１０^−９
Ａ_１０＝−１．２８０７７×１０^−１２
【００４３】
非球面：第２０面
Ｋ＝０
Ａ_４＝−６．８６２５６×１０^−５
Ａ_６＝２．３３０３７×１０^−６
Ａ_８＝−９．０２０５０×１０^−８
Ａ_１０＝１．６２９０４×１０^−９
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００４４】
【表２】
可変間隔

【００４５】
また、この第１の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内かまたはそれに近い値である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．５１６８０
ν_Ｃ２（ν_{１５−１６}）＝６４．２０
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．７５５２０
ν_Ｃ１（ν_{１４−１５}）＝２７．５３
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．７５５２０
ν_Ｃ３（ν_{１６−１７}）＝２７．５３
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝０．８９６（＝７．８００／８．７１０）
【００４６】
〔第２の実施例〕
図２は、本発明の第２の実施例に係るズームレンズの光学系の構成を示している。
図２に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図２には、参考のために各光学面の面番号の一部も付して示している。なお、図２に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００４７】
図２において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および光学フィルタＯＦの順で配列されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。
【００４８】
第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。第７レンズＥ７は、両凸レンズからなる正レンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、物体側に凸に形成された正メニスカスレンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。
【００４９】
第４レンズ群Ｇ４である第１２レンズＥ１２の像面側に配置された光学フィルタＯＦは、第４レンズ群Ｇ４と一体的に保持され、各種の光学フィルタリング機能を有する。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動する。
この第２の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜２３．２，Ｆ＝２．７７〜４．１７，ω＝４０．０８〜１１．０２の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００５０】
【表３】
光学特性

【００５１】
表３において「（非球面）」と記した第６面、第１２面、および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝７．５７０２６×１０^−５
Ａ_６＝−５．９１８７０×１０^−７
Ａ_８＝４．３２７０４×１０^−９
Ａ_１０＝−１．７８０４０×１０^−１１
【００５２】
非球面：第１２面
Ｋ＝０
Ａ_４＝−１．１４６４６×１０^−４
Ａ_６＝−１．２８３１９×１０^−７
Ａ_８＝−９．１３４５４×１０^−９
Ａ_１０＝５．０８４２７×１０^−１１
非球面：第２０面
Ｋ＝０
Ａ_４＝−６．３８６２０×１０^−５
Ａ_６＝３．９６４２６×１０^−６
Ａ_８＝−１．６５４６２×１０^−７
Ａ_１０＝３．０８３８６×１０^−９
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００５３】
【表４】
可変間隔

【００５４】
また、この第２の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．４８７４９
ν_Ｃ２（ν_{１５−１６}）＝７０．４４
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．６９８９５
ν_Ｃ１（ν_{１４−１５}）＝３０．０５
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．７５５２０
ν_Ｃ３（ν_{１６−１７}）＝２７．５３
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝０．９３６（＝７．８００／８．３３７）
【００５５】
〔第３の実施例〕
図３は、本発明の第３の実施例に係るズームレンズの光学系の構成を示している。
図３に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。なお、図３に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００５６】
図３において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および光学フィルタＯＦの順で配列されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、両凸レンズからなる正レンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。
【００５７】
第４レンズＥ４は、物体側に凸に形成された負メニスカスレンズ、第５レンズＥ５は、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。第７レンズＥ７は、物体側に凸に形成された正メニスカスレンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、物体側に凸に形成された正メニスカスレンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。
【００５８】
第４レンズ群Ｇ４である第１２レンズＥ１２の像面側に配置された光学フィルタＯＦは、第４レンズ群Ｇ４と一体的に保持され、各種の光学フィルタリング機能を有する。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、第３レンズ群Ｇ３の最も像面側に位置する第１１レンズＥ１１の像面側の面である第１９面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動する。
この第３の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝４．９５〜１４．８５，Ｆ＝２．９７〜４．１３，ω＝４４．４５〜１７．０７の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００５９】
【表５】
光学特性

【００６０】
表５において「（非球面）」と記した第６面、第１２面、第１９面、および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝７．６８１４３×１０^−５
Ａ_６＝−５．５７８７９×１０^−７
Ａ_８＝３．４３４６１×１０^−９
Ａ_１０＝−１．２６７７５×１０^−１１
非球面：第１２面
Ｋ＝０
Ａ_４＝−５．９０２４４×１０^−５
Ａ_６＝−２．２６３０７×１０^−８
Ａ_８＝３．９９６１８×１０^−８
Ａ_１０＝−１．４１０６４×１０^−９
【００６１】
非球面：第１９面
Ｋ＝０
Ａ_４＝４．１５８９０×１０^−４
Ａ_６＝６．３１０２４×１０^−６
Ａ_８＝−１．６０９９８×１０^−７
Ａ_１０＝９．６１８９６×１０^−９
非球面：第２０面
Ｋ＝０
Ａ_４＝−４．８３２３９×１０^−５
Ａ_６＝４．２４０８１×１０^−６
Ａ_８＝−３．４９８０７×１０^−７
Ａ_１０＝８．９３４３６×１０^−９
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００６２】
【表６】
可変間隔

【００６３】
また、この第３の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内かまたはそれに近い値である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．４８７４９
ν_Ｃ２（ν_{１５−１６}）＝７０．４４
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．７５５２０
ν_Ｃ１（ν_{１４−１５}）＝２７．５３
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．６７２７０
ν_Ｃ３（ν_{１６−１７}）＝３２．１７
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝０．２４９（＝７．２３０／２８．９９０）
【００６４】
〔第４の実施例〕
図４は、本発明の第４の実施例に係るズームレンズの光学系の構成を示している。
図４に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。なお、図４に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００６５】
図４において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および光学フィルタＯＦの順で配列されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３も、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。
【００６６】
第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。第７レンズＥ７は、物体側に凸に形成された正メニスカスレンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、物体側に凸に形成された正メニスカスレンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。
【００６７】
第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。第４レンズ群Ｇ４である第１２レンズＥ１２の像面側に配置された光学フィルタＯＦは、第４レンズ群Ｇ４と一体的に保持され、各種の光学フィルタリング機能を有する。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、第３レンズ群Ｇ３の最も像面側に位置する第１１レンズＥ１１の像面側の面である第１９面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動し、さらに第４レンズ群Ｇ４は移動しない。
この第４の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８０〜２９．００，Ｆ＝３．０１〜４．５８，ω＝４０．１６〜８．９１の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００６８】
【表７】
光学特性

【００６９】
表７において「（非球面）」と記した第６面、第１２面、第１９面および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝８．１２７１６×１０^−５
Ａ_６＝−４．７３７３７×１０^−７
Ａ_８＝２．３２９９５×１０^−９
Ａ_１０＝−６．６２２９４×１０^−１２
非球面：第１２面
Ｋ＝０
Ａ_４＝−４．０４９４０×１０^−５
Ａ_６＝１．０８３８７×１０^−７
Ａ_８＝２．１０７１１×１０^−９
Ａ_１０＝−９．７１４４５×１０^−１１
【００７０】
非球面：第１９面
Ｋ＝０
Ａ_４＝２．６６４２５×１０^−４
Ａ_６＝２．８３５２５×１０^−６
Ａ_８＝６．４２１６１×１０^−９
Ａ_１０＝１．４０７２５×１０^−１０
非球面：第２０面
Ｋ＝０
Ａ_４＝−５．６４２３６×１０^−５
Ａ_６＝−２．４６２８２×１０^−７
Ａ_８＝−１．０２４７９×１０^−８
Ａ_１０＝−１．５８９０３×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００７１】
【表８】
可変間隔

【００７２】
また、この第４の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．４８７４９
ν_Ｃ２（ν_{１５−１６}）＝７０．４４
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．７４９５０
ν_Ｃ１（ν_{１４−１５}）＝３５．０４
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．６９８９５
ν_Ｃ３（ν_{１６−１７}）＝３０．０５
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝０．９７５（＝１０．９９６／１１．２７５）
【００７３】
〔第５の実施例〕
図５は、本発明の第５の実施例に係るズームレンズの光学系の構成を示している。
図５に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および絞りＦＡを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。なお、図５に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００７４】
図５において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１および第１２レンズＥ１２の順で配列されており、第１２レンズＥ１２の背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３も、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、物体側に凸に形成された負メニスカスレンズ、第５レンズＥ５は、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。
【００７５】
第７レンズＥ７は、両凸レンズからなる正レンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、物体側に凸に形成された正メニスカスレンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
【００７６】
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動し、さらに第４レンズ群Ｇ４は、この場合、固定とされているが、主として第２レンズ群と第３レンズ群の移動にともなう像面の移動を補正すべく移動するようにすることができる。
この第５の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８０〜１７．３０，Ｆ＝２．８１〜４．２０，ω＝４０．９０〜１４．７０の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００７７】
【表９】
光学特性

【００７８】
表９において「（非球面）」と記した第６面、第１２面、および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝５．２３３２２×１０^−５
Ａ_６＝−１．０６４８７×１０^−６
Ａ_８＝１．５３０４１×１０^−８
Ａ_１０＝−１．０５１０７×１０^−１０
【００７９】
非球面：第１２面
Ｋ＝０
Ａ_４＝−２．３６２７１×１０^−４
Ａ_６＝８．２２２７９×１０^−７
Ａ_８＝−２．６６５３２×１０^−８
Ａ_１０＝１．５１６３７×１０^−１０
非球面：第２０面
Ｋ＝０
Ａ_４＝−２．１３８３７×１０^−４
Ａ_６＝１．０２６１７×１０^−５
Ａ_８＝−４．９６８９１×１０^−７
Ａ_１０＝１．３３３３５×１０^−８
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００８０】
【表１０】
可変間隔

【００８１】
また、この第５の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．５１６８０
ν_Ｃ２（ν_{１５−１６}）＝６４．２０
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．７１７３６
ν_Ｃ１（ν_{１４−１５}）＝２９．５０
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．７５５２０
ν_Ｃ３（ν_{１６−１７}）＝２７．５３
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝１．１１６（＝７．０８７／６．３４８）
【００８２】
〔第６の実施例〕
図６は、本発明の第６の実施例に係るズームレンズの光学系の構成を示している。
図６に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第６レンズＥ６は、第２レンズ群Ｇ２を構成し、第７レンズＥ７〜第１１レンズＥ１１は、第３レンズ群Ｇ３を構成し、第１２レンズＥ１２は第４レンズ群Ｇ４を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。なお、図６に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００８３】
図６において、例えば被写体等の物体側から、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、絞りＦＡ、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２および光学フィルタＯＦの順で配列されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３も、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、そして第６レンズＥ６は、両凸レンズからなる正レンズであり、第５レンズＥ５と第６レンズＥ６は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第６レンズＥ６により構成する第２レンズ群は、全体として負の焦点距離を呈する。
【００８４】
第７レンズＥ７は、両凸レンズからなる正レンズ、第８レンズＥ８は、 物体側に凸に形成された負メニスカスレンズ、第９レンズＥ９は、両凸レンズからなる正レンズ、第１０レンズＥ１０は、両凹レンズからなる負レンズ、そして第１１レンズＥ１１は、両凸レンズからなる正レンズであり、第８レンズＥ８〜第１０レンズＥ１０は、密に接合された３枚接合レンズであって、これら第７レンズＥ７〜第１１レンズＥ１１により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１２レンズＥ１２は、両凸レンズからなる正レンズであり、この第１２レンズＥ１２のみによって、正の焦点距離を有する第４レンズ群Ｇ４を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第２レンズ群Ｇ２との間の距離および第３レンズ群Ｇ３との間の距離をそれぞれ可変としている。第４レンズ群Ｇ４である第１２レンズＥ１２の像面側に配置された光学フィルタＯＦは、第４レンズ群Ｇ４と一体的に保持され、各種の光学フィルタリング機能を有する。第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第３レンズ群Ｇ３の最も物体側に位置する第７レンズＥ７の物体側の面である第１２面、そして第４レンズ群Ｇ４を構成する第１２レンズＥ１２の物体側の面である第２０面をそれぞれ非球面としている。
【００８５】
広角端、つまり短焦点端、から望遠端、つまり長焦点端、への変倍に伴って、第２レンズ群Ｇ２が物体側から像面側へと移動し、主として変倍作用および像面補正作用を担う第３レンズ群Ｇ３が像面側から物体側へと移動し、さらに第４レンズ群Ｇ４は、この場合、固定されているが、主として第２レンズ群と第３レンズ群の移動にともなう像面の移動を補正させるように移動するようにしてもよい。
この第６の実施例においては、全系の焦点距離ｆ、ＦナンバＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８０〜１７．３０，Ｆ＝２．８９〜４．０２，ω＝３９．９３〜１４．６５の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００８６】
【表１１】
光学特性

【００８７】
表１１において「（非球面）」と記した第６面、第１２面および第２０面の各光学面が非球面であり、各非球面における先に述べた式（１）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝１．１０５５８×１０^−４
Ａ_６＝−１．０１９７０×１０^−６
Ａ_８＝７．９３４９０×１０^−９
Ａ_１０＝−３．４９７４９×１０^−１１
非球面：第１２面
Ｋ＝０
Ａ_４＝−７．７０８８８×１０^−５
Ａ_６＝２．５５７３２×１０^−７
Ａ_８＝−７．９４４５０×１０^−１０
Ａ_１０＝−６．１３３３９×１０^−１１
【００８８】
非球面：第２０面
Ｋ＝０
Ａ_４＝−１．７６９２３×１０^−５
Ａ_６＝３．８３８２２×１０^−７
Ａ_８＝−８．１６７８８×１０^−９
Ａ_１０＝１．４００８７×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２群光学系Ｇ２と絞りＦＡとの間の間隔Ｄ_１０、絞りＦＡと第３レンズ群Ｇ３との間の間隔Ｄ_１１、そして第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９は、可変であり、これら可変間隔Ｄ_５，Ｄ_１０，Ｄ_１１，Ｄ_１９は、ズーミングに伴って次表のように変化させられる。
【００８９】
【表１２】
可変間隔

【００９０】
また、この第６の実施例における先に述べた本発明の各条件式に係る数値は、次の通りとなり、各条件式の範囲内の値である。
条件式数値
Ｎ_Ｃ２（Ｎ_{１５−１６}）＝１．５１６８０
ν_Ｃ２（ν_{１５−１６}）＝６４．２０
Ｎ_Ｃ１（Ｎ_{１４−１５}）＝１．６９８９５
ν_Ｃ１（ν_{１４−１５}）＝３０．０５
Ｎ_Ｃ３（Ｎ_{１６−１７}）＝１．７５５２０
ν_Ｃ３（ν_{１６−１７}）＝２７．５３
Ｒ_Ｃ２／Ｒ_Ｃ４（Ｒ_１５／Ｒ_１７）＝０．８９０（＝８．１００／９．１０５）
なお、図７は、第１の実施例のズームレンズの短焦点端における収差曲線図、図８は、第１の実施例のズームレンズの中間焦点距離における収差曲線図、そして図９は、第１の実施例のズームレンズの長焦点端における収差曲線図である。
【００９１】
また、図１０は、第２の実施例のズームレンズの短焦点端における収差曲線図、図１１は、第２の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１２は、第２の実施例のズームレンズの長焦点端における収差曲線図である。同様に図１３は、第３の実施例のズームレンズの短焦点端における収差曲線図、図１４は、第３の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１５は、第３の実施例のズームレンズの長焦点端における収差曲線図である。図１６は、第４の実施例のズームレンズの短焦点端における収差曲線図、図１７は、第４の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１８は、第４の実施例のズームレンズの長焦点端における収差曲線図である。図１９は、第５の実施例のズームレンズの短焦点端における収差曲線図、図２０は、第５の実施例のズームレンズの中間焦点距離における収差曲線図、そして図２１は、第５の実施例のズームレンズの長焦点端における収差曲線図である。
【００９２】
図２２は、第６の実施例のズームレンズの短焦点端における収差曲線図、図２３は、第６の実施例のズームレンズの中間焦点距離における収差曲線図、そして図２４は、第６の実施例のズームレンズの長焦点端における収差曲線図である。これら図７〜図２４の収差曲線図中、球面収差の図における実線は球面収差、破線は正弦条件をあらわしており、非点収差の図における実線はサジタル、そして破線はメリディオナルをあらわしている。これら各収差曲線図によっても、上述した各実施例により、良好な特性が得られていることがわかる。
なお、これら各実施例に示したズームレンズを撮影レンズとして用いてカメラを構成すれば、小型で且つ広画角および高画質のカメラを実現することができ、これら各実施例に示したズームレンズをカメラ機能部の撮影レンズとして用いて携帯情報端末装置を構成すれば、小型で且つ広画角および高画質のカメラ機能を有する携帯情報端末装置を実現することができる。
【００９３】
【発明の効果】
以上述べたように、本発明によれば、充分に小型で且つ広画角でありながら高性能であり、３００万〜５００万画素の撮像素子に対応する解像力を有するズームレンズ、並びにそれを用いるカメラおよび携帯情報端末装置を提供することができる。
すなわち本発明の請求項１のズームレンズによれば、物体側から像面側へ向かって、順次、正の屈折力を有し且つ変倍に伴って移動しない第１レンズ群と、負の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて物体側から像面側に移動する第２レンズ群と、正の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて像面側から物体側に移動する第３レンズ群と、正の屈折力を有し且つ変倍に伴って移動しない第４レンズ群と、が配置されてなるズームレンズにおいて、前記第３レンズ群が、負レンズ、正レンズおよび負レンズからなる３枚接合レンズを有することにより、充分に小型で且つ広画角でありながら高性能であり、３００万〜５００万画素の撮像素子に対応する解像力を有するズームレンズを提供することができ、特に、収差補正能力の高い第３レンズ群を実現し、変倍による収差変動を小さく抑え、各収差、とりわけ倍率色収差を充分に低減して、高い解像力を達成することが可能となる。
【００９４】
また、本発明の請求項２のズームレンズによれば、請求項１のズームレンズにおいて、前記３枚接合レンズのうちの最も物体側に配置される前記負レンズが、像面側に凹面を向けたメニスカス形状をなす負メニスカスレンズであることにより、特に、より充分な収差補正、特に球面収差、コマ収差および非点収差の補正が可能となる。
本発明の請求項３のズームレンズによれば、請求項１に記載のズームレンズにおいて、前記３枚接合レンズのうちの最も像面側に配置される前記負レンズが、像面側に凹面を向けた負レンズであることにより、特に、さらに充分な収差補正、特に、球面収差、コマ収差および非点収差の補正が可能となる。
本発明の請求項４のズームレンズによれば、請求項１に記載のズームレンズにおいて、前記３枚接合レンズの中間に配置される前記正レンズの屈折率およびアッベ数を、それぞれ、Ｎ_Ｃ２およびν_Ｃ２とすると、条件式：
１．４５＜Ｎ_Ｃ２＜１．５２
６８＜ν_Ｃ２＜８５
を満足することにより、特に、良好な色収差補正を可能とすると共に、コストの抑制が可能となる。
【００９５】
本発明の請求項５のズームレンズによれば、請求項４に記載のズームレンズにおいて、前記３枚接合レンズの最も物体側に配置される前記負レンズの屈折率およびアッベ数を、それぞれ、Ｎ_Ｃ１およびν_Ｃ１とし、且つ前記３枚接合レンズの最も像面側に配置される前記負レンズの屈折率およびアッベ数を、それぞれ、Ｎ_Ｃ３およびν_Ｃ３とすると、条件式：
１．６０＜Ｎ_Ｃ１＜１．９５
２０＜ν_Ｃ１＜４０
１．６０＜Ｎ_Ｃ３＜１．９５
２０＜ν_Ｃ３＜４０
を満足することにより、倍率色収差の良好な補正を可能とし、特に、短焦点端における倍率色収差を低減することが可能となる。
【００９６】
本発明の請求項６のズームレンズによれば、請求項１に記載のズームレンズにおいて、前記第３レンズ群の前記３枚接合レンズの物体側の接合面の曲率半径を、Ｒ_Ｃ２とし、且つ該第３レンズ群の３枚接合レンズの像面側の面の曲率半径を、Ｒ_Ｃ４はとすると、条件式：
０．２５＜（Ｒ_Ｃ２／Ｒ_Ｃ４）＜１．２５
を満足することにより、特に、単色色収差のさらなる改善が可能となる。
本発明の請求項７のズームレンズによれば、物体側から像面側へ向かって、順次、正の屈折力を有し且つ変倍に伴って移動しない第１レンズ群と、負の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて物体側から像面側に移動する第２レンズ群と、正の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて像面側から物体側に移動する第３レンズ群と、正の屈折力を有し且つ変倍に伴って移動しない第４レンズ群と、が配置されてなるズームレンズにおいて、前記第３レンズ群が、負レンズ、正レンズ、および負レンズからなる３枚接合レンズと、前記３枚接合レンズの物体側および像面側にそれぞれ少なくとも１枚ずつ配置される正レンズとを有することにより、充分に小型で且つ広画角でありながら高性能であり、３００万〜５００万画素の撮像素子に対応する解像力を有するズームレンズを提供することができ、特に、屈折力の配置のバランスを改善し、１つのレンズ面で過大な収差が発生することを防止して、偏心等の製造誤差による性能の劣化も小さく抑えることが可能となる。
【００９７】
本発明の請求項８のズームレンズによれば、請求項７に記載のズームレンズにおいて、前記３枚接合レンズの物体側および像面側に少なくとも１枚ずつ配置される前記正レンズのうちの少なくとも１枚が、非球面を有する非球面正レンズであることにより、特に、球面収差およびコマ収差または球面収差、コマ収差および非点収差を効果的に補正して、第３レンズ群の小型化、特に全長の短縮、が可能となる。
【００９８】
本発明の請求項９のズームレンズによれば、物体側から像面側へ向かって、順次、正の屈折力を有し且つ変倍に伴って移動しない第１レンズ群と、負の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて物体側から像面側に移動する第２レンズ群と、正の屈折力を有し且つ変倍に伴い広角端から望遠端にかけて像面側から物体側に移動する第３レンズ群と、正の屈折力を有し且つ変倍に伴って適宜移動する第４レンズ群と、が配置されてなるズームレンズにおいて、前記第３レンズ群が、負レンズ、正レンズおよび負レンズからなる３枚接合レンズを有することにより、充分に小型で且つ広画角でありながら高性能であり、３００万〜５００万画素の撮像素子に対応する解像力を有するズームレンズを提供することができ、特に、第４レンズ群を第３レンズ群との関連した動きをさせることにより、一層の高変倍比化、広画角化および小型化が可能となる。
【００９９】
また、本発明の請求項１０に記載の発明によれば、カメラの撮影用光学系として、請求項１〜９のうちのいずれか１項に記載された前記ズームレンズを備えることにより、特に、撮影用光学系としてのズームレンズにおける変倍による収差変動を小さく抑え、各収差を低減し、高い解像力を達成して、充分に小型で且つ広画角でありながら高性能の撮影光学系を備えたカメラを提供することができる。
そして、本発明の請求項１１に記載の発明によれば、カメラ機能部の撮影用光学系として、請求項１〜９のうちのいずれか１項に記載された前記ズームレンズを備えることにより、特に、撮影機能部の撮影用光学系としてのズームレンズにおける変倍による収差変動を小さく抑え、各収差を低減し、高い解像力を達成して、充分に小型で且つ広画角でありながら高性能の撮影光学系をカメラ機能部に備えた携帯情報端末装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係るズームレンズの第１の実施例の光学系の構成を示す模式図である。
【図２】本発明の第１の実施の形態に係るズームレンズの第２の実施例の光学系の構成を示す模式図である。
【図３】本発明の第１の実施の形態に係るズームレンズの第３の実施例の光学系の構成を示す模式図である。
【図４】本発明の第１の実施の形態に係るズームレンズの第４の実施例の光学系の構成を示す模式図である。
【図５】本発明の第１の実施の形態に係るズームレンズの第５の実施例の光学系の構成を示す模式図である。
【図６】本発明の第１の実施の形態に係るズームレンズの第６の実施例の光学系の構成を示す模式図である。
【図７】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図８】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図９】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１０】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図１１】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１２】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１３】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図１４】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１５】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１６】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図１７】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１８】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１９】本発明の第１の実施の形態に係るズームレンズの図５に示す第５の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図２０】本発明の第１の実施の形態に係るズームレンズの図５に示す第５の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図２１】本発明の第１の実施の形態に係るズームレンズの図５に示す第５の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図２２】本発明の第１の実施の形態に係るズームレンズの図６に示す第６の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図２３】本発明の第１の実施の形態に係るズームレンズの図６に示す第６の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図２４】本発明の第１の実施の形態に係るズームレンズの図６に示す第６の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【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
ＦＡ 絞り
ＯＦ 光学フィルタ
Ｅ１ 第１レンズ
Ｅ２ 第２レンズ
Ｅ３ 第３レンズ
Ｅ４ 第４レンズ
Ｅ５ 第５レンズ
Ｅ６ 第６レンズ
Ｅ７ 第７レンズ
Ｅ８ 第８レンズ
Ｅ９ 第９レンズ
Ｅ１０ 第１０レンズ
Ｅ１１ 第１１レンズ
Ｅ１２ 第１２レンズ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement in a zoom lens that independently controls the driving of a plurality of lens groups and changes a focal length by individually moving at least a part of the lens groups along an optical axis direction. The present invention relates to a zoom lens suitable for a camera such as a video camera using electronic imaging means, a camera using the zoom lens, and a portable information terminal device.
[0002]
[Prior art]
In recent years, a digital camera equipped with a variable focus mechanism such as a zoom lens barrel that can selectively switch between a wide-angle state where the focal length of the shooting lens is short and the field angle is wide and a telephoto state where the focal length is long and the field angle is narrow Is widespread. The needs of users of digital cameras equipped with this kind of variable focus mechanism are diverse, and among them, the needs for high image quality and miniaturization are by far the highest. Therefore, a zoom lens used as a photographing lens is also required to have both high performance and small size.
Here, in terms of miniaturization, first, it is necessary to shorten the entire length of the lens, that is, the distance from the lens surface closest to the object to the image surface. Furthermore, from the aspect of high performance, it is necessary to have a resolving power corresponding to an image sensor having at least 3 to 5 million pixels over the entire zoom range.
In addition, many users desire a wide angle of view of the photographing lens, and it is desirable that the half angle of view on the wide angle end side of the zoom lens be 38 degrees or more. The half angle of view of 38 degrees corresponds to a 35 mm silver halide film camera, a so-called Leica camera, equivalent to a converted focal length of 28 mm.
[0003]
[Patent Document 1]
Japanese Patent No. 2920549
[Patent Document 2]
Japanese Patent No. 3091250
[Patent Document 3]
JP-A-6-94997
[Patent Document 4]
JP-A-10-62887
[Patent Document 5]
[0004]
JP-A-11-258507
Conventionally, as a zoom lens of this kind, which has been miniaturized for consumer use, for example, as described in Patent Document 1 and Patent Document 2 described above, the zoom lens moves from the object side to the image plane side. A first lens group having a positive refractive power and not moving with zooming in sequence, and a first lens group having negative refractive power and moving from the object side to the image plane side from the wide-angle end to the telephoto end with zooming. A second lens group that moves, a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide angle end to the telephoto end with zooming, and a third lens group that has a positive refractive power and And a fourth lens group that does not move with magnification. However, those disclosed in Patent Literature 1 and Patent Literature 2 each have a half angle of view of less than 25 degrees, which is not yet sufficient in terms of widening the angle of view.
[0005]
Further, for example, as shown in Patent Literature 3, Patent Literature 4, and Patent Literature 5, the fourth lens group having substantially the same configuration as described above can be moved with zooming to perform more advanced aberration correction. By doing so, there has been proposed a device in which the size and the angle of view are further reduced. Patent Literature 3 discloses all the basic configurations in this case, but does not present sufficient configuration requirements in terms of miniaturization. The device disclosed in Patent Document 4 aims at miniaturization by reducing the number of components, but does not perform sufficient aberration correction, and has a performance capable of supporting an image sensor having 3 to 5 million pixels. I haven't. The one disclosed in Patent Document 5 is relatively small, and the image performance is better than that described above, but the half angle of view is only about 33 degrees, which is still insufficient in terms of widening the angle of view. Not really.
[0006]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described circumstances, has a sufficiently small size and a high performance while having a wide angle of view, and a zoom lens having a resolution corresponding to an image sensor of 3 to 5 million pixels, and It is an object to provide a camera and a portable information terminal device using the same.
An object of claim 1 of the present invention is to realize, in particular, a third lens group having a high aberration correction capability, to suppress aberration fluctuation due to zooming to a small extent, and to sufficiently reduce each aberration, especially chromatic aberration of magnification, to achieve high resolution. It is to provide a achievable zoom lens.
It is an object of claim 2 of the present invention to provide a zoom lens that enables more sufficient aberration correction, particularly, spherical aberration and coma aberration.
An object of claim 3 of the present invention is to provide a zoom lens that enables more sufficient aberration correction, particularly correction of spherical aberration, coma aberration, and astigmatism.
An object of a fourth aspect of the present invention is to provide a zoom lens that enables good chromatic aberration correction and suppresses an increase in cost.
[0007]
An object of claim 5 of the present invention is to provide a zoom lens which enables good correction of chromatic aberration of magnification, and in particular, reduces chromatic aberration of magnification at the short focal length end.
An object of claim 6 of the present invention is to provide a zoom lens capable of further improving monochromatic aberration.
The object of claim 7 of the present invention is to improve the balance of the arrangement of the refractive power, prevent the generation of excessive aberration on one lens surface, and reduce the performance degradation due to manufacturing errors such as eccentricity. It is an object of the present invention to provide a zoom lens capable of suppressing the zoom lens.
An object of claim 8 of the present invention is to effectively correct spherical aberration and coma or spherical aberration, coma and astigmatism, and make it possible to reduce the size of the third lens group, particularly to shorten the overall length. To provide a zoom lens.
[0008]
An object of a ninth aspect of the present invention is to provide a zoom lens capable of achieving a higher zoom ratio, a wider angle of view, and a smaller size.
An object of claim 10 of the present invention is to suppress aberration fluctuation due to zooming in a zoom lens as a photographing optical system, reduce each aberration, achieve high resolution, and achieve a sufficiently small and wide image. It is an object of the present invention to provide a camera capable of achieving a high-performance imaging optical system while having a corner.
An object of claim 11 of the present invention is to reduce aberration fluctuation due to zooming in a zoom lens as a photographing optical system of a photographing function unit, reduce each aberration, achieve high resolution, and achieve a sufficiently small size. Another object of the present invention is to provide a portable information terminal device capable of achieving a high-performance photographing optical system while having a wide angle of view.
[0009]
[Means for Solving the Problems]
The zoom lens according to the first aspect of the present invention has the following features.
A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side toward and a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and not moving with zooming.
The third lens group has a triplet including a negative lens, a positive lens, and a negative lens.
It is characterized by:
The zoom lens according to a second aspect of the present invention is the zoom lens according to the first aspect,
The negative lens disposed closest to the object among the three cemented lenses is a negative meniscus lens having a meniscus shape with a concave surface facing the image plane side.
[0010]
A zoom lens according to a third aspect of the present invention is the zoom lens according to the first aspect,
The negative lens disposed closest to the image plane among the three cemented lenses is a negative lens having a concave surface facing the image plane.
The zoom lens according to a fourth aspect of the present invention is the zoom lens according to the first aspect,
The refractive index and Abbe number of the positive lens arranged in the middle of the three cemented lenses are respectively N_C2And ν_C2Then the conditional expression:
1.45 <N_C2<1.52
68 <ν_C2<85
It is characterized by satisfying.
[0011]
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to the fourth aspect,
The refractive index and Abbe number of the negative lens arranged closest to the object side of the triplet_C1And ν_C1And the refractive index and Abbe number of the negative lens arranged closest to the image plane side of the three cemented lens are respectively N_C3And ν_C3Then the conditional expression:
1.60 <N_C1<1.95
20 <ν_C1<40
1.60 <N_C3<1.95
20 <ν_C3<40
It is characterized by satisfying.
[0012]
The zoom lens according to the present invention described in claim 6 is the zoom lens according to claim 1,
The radius of curvature of the cemented surface on the object side of the three cemented lens of the third lens group is represented by R_C2And the radius of curvature of the image-side surface of the three cemented lenses in the third lens group is R_C4Then the conditional expression:
0.25 <(R_C2/ R_C4) <1.25
It is characterized by satisfying.
[0013]
According to a seventh aspect of the present invention, there is provided a zoom lens for achieving the above object.
A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side toward and a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and not moving with zooming.
The third lens group includes:
A three cemented lens comprising a negative lens, a positive lens, and a negative lens;
A positive lens disposed at least one each on the object side and the image plane side of the triplet lens;
It is characterized by having.
[0014]
The zoom lens according to the present invention described in claim 8 is the zoom lens according to claim 7,
At least one of the positive lenses disposed on the object side and the image plane side of the triplet lens is at least one aspherical positive lens having an aspherical surface.
According to the ninth aspect of the present invention, in order to achieve the above object,
A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side from the object side, a third lens group that has a positive refractive power, and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and moving appropriately with zooming.
The third lens group has a triplet lens composed of a negative lens, a positive lens, and a negative lens.
[0015]
According to a tenth aspect of the present invention, there is provided a camera including the zoom lens according to any one of the first to ninth aspects as a photographing optical system.
A portable information terminal device according to an eleventh aspect of the present invention includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system of a camera function unit. It is characterized by.
[0016]
[Action]
That is, the zoom lens according to claim 1 of the present invention includes a first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side, and a negative refractive power. And a second lens unit that moves from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and the image side that has a positive refractive power and moves from the wide-angle end to the telephoto end with zooming And a fourth lens group having a positive refracting power and not moving with zooming, is disposed in a zoom lens, wherein the third lens group has a negative refractive power. It has a triplet lens consisting of a lens, a positive lens and a negative lens.
With such a configuration, it is possible to provide a zoom lens that is sufficiently small and has high performance while having a wide angle of view, and has a resolution corresponding to an image sensor having 3 to 5 million pixels. It is possible to realize a high-performance third lens unit, suppress aberration fluctuations due to zooming to a small extent, and sufficiently reduce each aberration, particularly chromatic aberration of magnification, to achieve high resolution.
[0017]
A zoom lens according to a second aspect of the present invention is the zoom lens according to the first aspect, wherein the negative lens disposed closest to the object side among the three cemented lenses has a meniscus shape having a concave surface facing the image plane side. This is a negative meniscus lens.
With such a configuration, more sufficient aberration correction, particularly correction of spherical aberration, coma, and astigmatism, can be performed.
In the zoom lens according to a third aspect of the present invention, in the zoom lens according to the first aspect, the negative lens of the three cemented lenses disposed closest to the image plane has a concave surface facing the image plane. It is a negative lens.
With such a configuration, in particular, more sufficient aberration correction, particularly correction of spherical aberration, coma, and astigmatism, can be performed.
[0018]
A zoom lens according to a fourth aspect of the present invention is the zoom lens according to the first aspect, wherein the refractive index and the Abbe number of the positive lens disposed in the middle of the three cemented lenses are each N_C2And ν_C2Then the conditional expression:
1.45 <N_C2<1.52
68 <ν_C2<85
To be satisfied.
With such a configuration, in particular, it is possible to perform good chromatic aberration correction and to suppress an increase in cost.
[0019]
In a zoom lens according to a fifth aspect of the present invention, in the zoom lens according to the fourth aspect, the refractive index and the Abbe number of the negative lens disposed closest to the object side of the three-element cemented lens are respectively set to N._C1And ν_C1And the refractive index and Abbe number of the negative lens arranged closest to the image plane side of the three cemented lens are respectively N_C3And ν_C3Then the conditional expression:
1.60 <N_C1<1.95
20 <ν_C1<40
1.60 <N_C3<1.95
20 <ν_C3<40
To be satisfied.
With such a configuration, in particular, it is possible to favorably correct lateral chromatic aberration, and particularly to reduce lateral chromatic aberration at the short focal length end.
[0020]
A zoom lens according to a sixth aspect of the present invention is the zoom lens according to the first aspect, wherein a radius of curvature of a cemented surface on the object side of the three cemented lens in the third lens group is R._C2And the radius of curvature of the image-side surface of the three cemented lenses in the third lens group is R_C4Then, the conditional expression:
0.25 <(R_C2/ R_C4) <1.25
To be satisfied.
With such a configuration, in particular, monochromatic chromatic aberration can be further improved.
[0021]
A zoom lens according to a seventh aspect of the present invention has a first lens group that has a positive refractive power and does not move with zooming in order from the object side to the image plane side, and has a negative refractive power. A second lens unit that moves from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and an object from the image plane side that has a positive refractive power and moves from the wide-angle end to the telephoto end with zooming. A third lens group that moves to the side and a fourth lens group that has a positive refractive power and does not move with zooming, wherein the third lens group is a negative lens, It has a three cemented lens composed of a positive lens and a negative lens, and at least one positive lens arranged on each of the object side and the image plane side of the three cemented lens.
With such a configuration, it is possible to provide a zoom lens having a sufficiently small size and a high performance while having a wide angle of view, and having a resolution corresponding to an image sensor having 3 to 5 million pixels. Can be improved, and excessive aberration can be prevented from being generated on one lens surface, and deterioration in performance due to manufacturing errors such as eccentricity can be suppressed.
[0022]
A zoom lens according to an eighth aspect of the present invention is the zoom lens according to the seventh aspect, wherein at least one of the positive lenses disposed on the object side and the image plane side of the three-element cemented lens. Is an aspheric positive lens having an aspheric surface.
With such a configuration, in particular, spherical aberration and coma or spherical aberration, coma and astigmatism can be effectively corrected, and the third lens unit can be reduced in size, particularly, the overall length can be reduced.
A zoom lens according to a ninth aspect of the present invention has a first lens group that has a positive refractive power and does not move with zooming in order from the object side to the image plane side, and has a negative refractive power. A second lens unit that moves from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and an object from the image plane side that has a positive refractive power and moves from the wide-angle end to the telephoto end with zooming. In a zoom lens in which a third lens group that moves to the side and a fourth lens group that has a positive refractive power and moves as appropriate with zooming are arranged, the third lens group is a negative lens. , A positive lens and a negative lens. With such a configuration, it is possible to provide a zoom lens that is sufficiently small and has a high performance while having a wide angle of view, and has a resolution corresponding to an image sensor having 3 to 5 million pixels. Higher zoom ratio, wider angle of view, and smaller size are possible.
[0023]
A camera according to a tenth aspect of the present invention includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system.
With such a configuration, particularly, aberration fluctuation due to zooming of a zoom lens as a photographing optical system is reduced, each aberration is reduced, high resolution is achieved, and a sufficiently small size and wide angle of view are achieved. It is possible to achieve a high-performance imaging optical system.
A portable information terminal device according to an eleventh aspect of the present invention includes the zoom lens according to any one of the first to ninth aspects as a photographing optical system of a camera function unit.
With such a configuration, in particular, aberration fluctuation due to zooming in a zoom lens as a photographing optical system of a photographing function unit is suppressed to be small, each aberration is reduced, a high resolution is achieved, and a sufficiently small and wide image is obtained. It is possible to achieve a high-performance photographing optical system despite the angle.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a zoom lens, a camera, and a portable information terminal device of the present invention will be described in detail with reference to the drawings based on embodiments of the present invention and examples showing specific numerical examples. The first embodiment of the present invention is an embodiment of the zoom lens according to the present invention, and the second embodiment of the present invention is shown in the first embodiment although not shown. It is an embodiment of a camera or a portable information terminal device according to the present invention using such a zoom lens as a photographing optical system.
First, the principle configuration of the zoom lens according to the first embodiment of the present invention will be described.
The zoom lens according to the present invention includes, in order from the object side to the image plane side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The zoom lens includes a lens group and a fourth lens group having a positive refractive power, that is, four lens groups of positive-negative-positive-positive. With zooming to the telephoto end, the second lens group moves from the object side to the image plane side, and the third lens group moves from the image plane side to the object side (claims 1 and 7). Corresponding to).
[0025]
In another zoom lens configuration according to the present invention, with zooming from the wide-angle end to the telephoto end, the second lens group moves from the object side to the image plane side, and the third lens group moves The fourth lens group moves from the surface side to the object side, and further moves (corresponding to claim 9). The fourth lens group is a lens group mainly serving to correct the movement of the image plane due to the movement of the second lens group and the third lens group.
In order to realize a zoom lens having a high resolution and a small amount of aberrations, it is necessary to suppress aberration fluctuations due to zooming. In particular, the zooming action (corresponding to claim 9), or zooming and image plane correction. It is necessary that the third lens group that performs two functions (corresponding to claim 1 and claim 7) is properly corrected for aberration over the entire zoom range. Furthermore, in order to achieve a wide angle of view at the wide-angle end, it is necessary to reduce the chromatic aberration of magnification that increases with the wide angle of view, and to satisfactorily correct this over the entire zoom range, Again, the configuration of the third lens group is important.
[0026]
Conventionally, as a configuration of a third lens group, a two-lens configuration in which a positive lens and a negative lens are sequentially arranged from the object side to the image plane side, a positive lens, a negative lens, and a positive lens Are known, and those having a three-lens structure in which a positive lens, a positive lens, and a negative lens are arranged are known. However, the present invention has an aberration correction capability exceeding these. This realizes the third lens group.
That is, in the zoom lens according to the present invention, the third lens group has a three-element cemented lens in which a negative lens, a positive lens, and a negative lens are cemented. The two joining surfaces have different distances from the stop, and also have different ways of passing light rays on and off the optical axis. With such two joining surfaces, it is possible to correct the axial chromatic aberration and the chromatic aberration of magnification to some extent independently, and it is particularly effective in correcting the chromatic aberration of magnification that increases with an increase in the angle of view. In order to provide two cemented surfaces, it is conceivable to use two cemented lenses. However, when the optical axes of the cemented lenses are displaced due to eccentricity during assembly, the chromatic aberration of magnification becomes asymmetric off-axis. And unnatural color bleeding easily occurs. On the other hand, when the three cemented lenses are used as described above, eccentricity does not occur when the two cemented surfaces are assembled, and chromatic aberration of magnification can be sufficiently reduced even in an actual configuration.
[0027]
In order to perform more sufficient aberration correction, it is desirable that the negative lens disposed closest to the object side of the three cemented lenses of the third lens group has a meniscus shape with the concave surface facing the image side. Corresponding to). The object side surface of this negative lens is a convex surface so as to prevent the occurrence of unnecessary aberrations without refracting an incident light beam too much, and the image side surface of the negative lens is a strong concave surface to mainly correct spherical aberration and coma. ing.
In order to perform more sufficient aberration correction, it is desirable that the negative lens disposed closest to the image side of the three cemented lenses of the third lens group has a strong concave surface facing the image side. Do). The image side surface of the negative lens is a strong concave surface, which performs secondary correction of spherical aberration and coma, and also contributes to correction of astigmatism.
[0028]
For good chromatic aberration correction, it is desirable to satisfy the following conditional expression (corresponding to claim 4).
1.45 <N_C2<1.52
68 <ν_C2<85
Where N_C2And ν_C2Represents the refractive index and Abbe number of the positive lens disposed in the middle of the three cemented lenses in the third lens group, respectively. N_C2Is 1.52 or more, ν_C2Is 68 or less, it is difficult to balance axial chromatic aberration with other aberrations, and axial chromatic aberration particularly at the long focal end is likely to occur. Further, in this case, the effect of correcting monochromatic aberration at the cemented surface on the object side cannot be sufficiently obtained. On the other hand, N_C2Is 1.45 or less, ν_C2Is 85 or more, it is advantageous for aberration correction, but such a glass material is expensive, and causes unnecessary increase in cost.
[0029]
In order to better correct lateral chromatic aberration, it is desirable to satisfy the following conditional expression (corresponding to claim 5).
1.60 <N_C1<1.95
20 <ν_C1<40
1.60 <N_C3<1.95
20 <ν_C3<40
Where N_C1, And ν_C1Respectively represent the refractive index and Abbe number of the negative lens disposed closest to the object side of the three cemented lenses in the third lens group, and N_C3And ν_C3Respectively represent the refractive index and Abbe number of the negative lens arranged closest to the image side of the three cemented lenses in the third lens group. N mentioned earlier_C3And ν_C3By satisfying these conditional expressions in addition to the conditional expressions regarding, it is possible to balance axial chromatic aberration and lateral chromatic aberration, and particularly to reduce lateral chromatic aberration at the short focal length end. At this time, it is possible to keep the monochromatic aberration correction state favorable.
[0030]
In order to further improve the monochromatic aberration, it is desirable to satisfy the following conditional expression (corresponding to claim 6).
0.25 <(R_C2/ R_C4) <1.25
Where R_C2Represents the radius of curvature of the cemented surface on the object side of the three cemented lenses in the third lens group, and R_C4Represents the radius of curvature of the most image side surface of the triplet lens in the third lens unit. (R_C2/ R_C4) Is 1.25 or more, spherical aberration at the long focal length end is likely to be large in the positive direction, which causes deterioration of image contrast. On the other hand, (R_C2/ R_C4) Is less than 0.25, the ability to correct astigmatism and curvature of field tends to be insufficient. This is a factor that deteriorates the flatness of the image plane in the entire zoom range.
[0031]
In the zoom lens according to the present invention, the third lens group includes a cemented triplet including a negative lens, a positive lens, and a negative lens, and at least one positive lens disposed on the object side and the image side thereof. It is more desirable to have a lens (corresponding to claim 7). The triplet lens has two concave surfaces having a strong negative refractive power, and in order to sufficiently bring out this aberration correction capability, it is necessary to arrange a positive refractive power that opposes this. If a positive lens is disposed on both the object side and the image side of the triplet, the third lens group as a whole has a positive-negative-positive-negative-positive configuration, and a very balanced refractive power arrangement. Is good. By adopting such a configuration, it is possible to prevent occurrence of excessive aberration on one lens surface, and to minimize deterioration of the formation due to a manufacturing error such as eccentricity.
[0032]
Further, in order to reduce the size of the third lens unit, particularly to shorten the overall length, it is effective to use an aspheric surface for the third lens unit. At this time, the aspherical surface is preferably provided on one or both of the positive lenses disposed on the object side and the image side of the three-element cemented lens (corresponding to claim 8). The positive lens on the object side is close to the stop and is effective mainly for correcting spherical aberration and coma. Since the positive lens on the image side is far from the stop and the off-axis light flux passes through it to some extent, it is effective in correcting astigmatism in addition to spherical aberration and coma.
In the zoom lens according to the present invention, as described above, a configuration in which the fourth lens group is moved may be considered (corresponding to claim 9). By adopting such a configuration and devising the movement related to the third lens group, it is possible to achieve a higher zoom ratio, a wider angle of view, and a smaller size.
[0033]
Next, a principle configuration of a camera or a portable information terminal device according to a second embodiment of the present invention will be described.
A camera (not shown) according to the present invention includes the above-described zoom lens as a photographing optical system. A camera equipped with such a zoom lens as a photographing optical system has a sufficiently small size and a wide angle of view by suppressing aberration fluctuation due to zooming in the zoom lens, reducing each aberration, and achieving high resolution. While achieving a high-performance shooting optical system.
Further, a portable information terminal device according to the present invention includes the above-described zoom lens as a photographing optical system of a camera function unit. A portable information terminal device equipped with such a zoom lens as a photographing optical system of a photographing function unit suppresses aberration fluctuation due to zooming of the zoom lens, reduces each aberration, achieves high resolution, and is sufficiently small in size. And achieves a high-performance imaging optical system with a wide angle of view.
[0034]
【Example】
Next, several examples showing specific numerical configurations of the zoom lens according to the first embodiment of the present invention will be described in detail.
Specific examples and numerical examples of the zoom lens according to the first embodiment of the present invention will be described below. In each embodiment, the aberration of the zoom lens is sufficiently corrected, and it is possible to correspond to a light receiving element having 3 to 5 million pixels. It is clear from each of the examples that by configuring the zoom lens as in the first embodiment, it is possible to secure a very good image performance while achieving a sufficiently small size and a wide angle of view. There will be.
In the following description relating to each embodiment, the following various symbols are used.
[0035]
f: focal length of the whole system
F: F number
ω: Half angle of view
R: radius of curvature
D: Surface spacing
N_d: Refractive index
ν_d: Abbe number
K: aspherical conical constant
A₄: 4th order aspheric coefficient
A₆: 6th order aspheric coefficient
A₈: 8th order aspheric coefficient
A₁₀: 10th order aspheric coefficient
However, the aspheric surface used here is defined by the following equation, where C is the reciprocal of the paraxial curvature radius (paraxial curvature) and H is the height from the optical axis.
[0036]
(Equation 1)

[0037]
[First embodiment]
FIG. 1 shows a configuration of an optical system of a zoom lens according to a first embodiment of the present invention.
The zoom lens shown in FIG. 1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. FIG. 1 also shows a part of the surface number of each optical surface for reference. 1 are used independently for each embodiment in order to avoid complication of the description due to an increase in the number of digits of the reference code. The configuration is not necessarily the same as the embodiment.
[0038]
In FIG. 1, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens, for example, sequentially from the object side such as a subject. E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and an optical filter OF, which are arranged in this order, behind the optical filter OF having various optical filtering functions. Is imaged.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is formed convex on the object side. The first lens E1 and the second lens E2 are tightly cemented two cemented lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole. The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, and the sixth lens E6 is a positive lens composed of a biconvex lens. The fifth lens E5 and the sixth lens E6 is a double cemented lens that is tightly cemented. The second lens group constituted by the fourth to sixth lenses E4 to E6 has a negative focal length as a whole.
[0039]
The seventh lens E7 is a positive lens formed of a biconvex lens, the eighth lens E8 is a negative meniscus lens formed convex on the object side, the ninth lens E9 is a positive lens formed of a biconvex lens, and the tenth lens E10 is The negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. The third lens group G3 including the lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive meniscus lens convexly formed on the object side, and only the twelfth lens E12 forms a fourth lens group G4 having a positive focal length. The diaphragm FA disposed between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable. The optical filter OF disposed on the image plane side of the twelfth lens E12, which is the fourth lens group G4, is held integrally with the fourth lens group G4 and has various optical filtering functions. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface and the twentieth surface which is the object-side surface of the twelfth lens E12 forming the fourth lens unit G4 are aspherical.
[0040]
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3 that performs the action moves from the image plane side to the object side.
In the first embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 5.8-17.3, F = 2.71-3.88 due to zooming, respectively. , Ω = 40.98 to 14.65. The optical characteristics associated with each optical surface and optical element are as follows.
[0041]
[Table 1]
optical properties

[0042]
In Table 1, each of the sixth, twelfth, and twentieth optical surfaces described as “(aspheric surface)” is an aspheric surface, and the parameter of each aspheric surface according to Equation (1) described above is Is as follows.
Aspheric surface: 6th surface
K = 0
A₄= 1.12052 × 10^-4
A₆= −8.1077 × 10^-7
A₈= 4.6470 × 10^-5
A₁₀= −1.54132 × 10^-11
Aspheric surface: 12th surface
K = 0
A₄= −7.35995 × 10^-5
A₆= 7.34774 × 10^-8
A₈= −6.337395 × 10^-9
A₁₀= -1.28077 × 10^-12
[0043]
Aspheric surface: 20th surface
K = 0
A₄= −6.886256 × 10^-5
A₆= 2.33037 × 10^-6
A₈= −9.02050 × 10^-8
A₁₀= 1.62904 × 10^-9
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0044]
[Table 2]
Variable interval

[0045]
The numerical values according to the above-described conditional expressions of the present invention in the first embodiment are as follows, and are values within or close to the range of each conditional expression.
Conditional expression
N_C2(N_15-16) = 1.51680
ν_C2(Ν_15-16) = 64.20
N_C1(N_14-15) = 1.75520
ν_C1(Ν_14-15) = 27.53
N_C3(N_16-17) = 1.75520
ν_C3(Ν_16-17) = 27.53
R_C2/ R_C4(R_Fifteen/ R₁₇) = 0.896 (= 7.800 / 8.710)
[0046]
[Second embodiment]
FIG. 2 shows a configuration of an optical system of a zoom lens according to a second embodiment of the present invention.
The zoom lens shown in FIG. 2 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. FIG. 2 also shows a part of the surface number of each optical surface for reference. Note that, as described above, each reference numeral for FIG. 2 is used independently for each embodiment, and even if a common reference numeral is assigned, it does not necessarily have a common configuration with other embodiments.
[0047]
In FIG. 2, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens, for example, sequentially from the object side such as a subject. E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and an optical filter OF, which are arranged in this order, behind the optical filter OF having various optical filtering functions. Is imaged.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is formed convex on the object side. The first lens E1 and the second lens E2 are tightly cemented two cemented lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole.
[0048]
The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, and the sixth lens E6 is a positive lens composed of a biconvex lens. The fifth lens E5 and the sixth lens E6 is a double cemented lens that is tightly cemented. The second lens group constituted by the fourth to sixth lenses E4 to E6 has a negative focal length as a whole. The seventh lens E7 is a positive lens composed of a biconvex lens, the eighth lens E8 is a negative meniscus lens convexly formed on the object side, the ninth lens E9 is a positive lens composed of a biconvex lens, and the tenth lens E10 is The negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. The third lens group G3 including the lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive meniscus lens convexly formed on the object side. The twelfth lens E12 alone forms a fourth lens group G4 having a positive focal length. The diaphragm FA arranged between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable.
[0049]
The optical filter OF disposed on the image plane side of the twelfth lens E12, which is the fourth lens group G4, is held integrally with the fourth lens group G4 and has various optical filtering functions. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface and the twentieth surface which is the object-side surface of the twelfth lens E12 forming the fourth lens unit G4 are aspherical.
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3 that performs the action moves from the image plane side to the object side.
In the second embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 5.8 to 23.2 and F = 2.77 to 4.17, respectively, by zooming. , Ω = 40.08 to 11.02. The optical properties associated with each optical surface and optical element are as follows.
[0050]
[Table 3]
optical properties

[0051]
In Table 3, each of the sixth, twelfth, and twentieth optical surfaces described as “(aspherical surface)” is an aspherical surface, and the parameter of each aspherical surface according to Equation (1) described above is Is as follows.
Aspheric surface: 6th surface
K = 0
A₄= 7.507026 × 10^-5
A₆= −5.991870 × 10^-7
A₈= 4.32704 × 10^-9
A₁₀= -1.78040 × 10^-11
[0052]
Aspheric surface: 12th surface
K = 0
A₄= −1.14646 × 10^-4
A₆= −1.28319 × 10^-7
A₈= −9.1454 × 10^-9
A₁₀= 5.0847 × 10^-11
Aspheric surface: 20th surface
K = 0
A₄= −6.38620 × 10^-5
A₆= 3.96426 × 10^-6
A₈= -1.665462 x 10^-7
A₁₀= 3.08386 × 10^-9
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0053]
[Table 4]
Variable interval

[0054]
The numerical values related to the above-described conditional expressions of the present invention in the second embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
N_C2(N_15-16) = 1.48749
ν_C2(Ν_15-16) = 70.44
N_C1(N_14-15) = 1.69895
ν_C1(Ν_14-15) = 30.05
N_C3(N_16-17) = 1.75520
ν_C3(Ν_16-17) = 27.53
R_C2/ R_C4(R_Fifteen/ R₁₇) = 0.936 (= 7.800 / 8.337)
[0055]
[Third embodiment]
FIG. 3 shows a configuration of an optical system of a zoom lens according to a third embodiment of the present invention.
The zoom lens shown in FIG. 3 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. Note that, as described above, each reference numeral for FIG. 3 is used independently for each embodiment, and even if a common reference numeral is assigned, it is not necessarily a common configuration in other embodiments.
[0056]
In FIG. 3, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens are sequentially arranged, for example, from the object side such as a subject. E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and an optical filter OF, which are arranged in this order, behind the optical filter OF having various optical filtering functions. Is imaged.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive lens formed of a biconvex lens, and the third lens E3 is a positive meniscus lens formed on the object side. The first lens E1 and the second lens E2 are two cemented lenses that are tightly cemented, and the first lens group G1 including the first lens E1 to the third lens E3 is positive as a whole. Present focal length.
[0057]
The fourth lens E4 is a negative meniscus lens formed convex on the object side, the fifth lens E5 is a negative lens formed of a biconcave lens, and the sixth lens E6 is a positive lens formed of a biconvex lens. The fifth lens E5 and the sixth lens E6 are two cemented lenses that are tightly cemented, and the second lens group including the fourth lens E4 to the sixth lens E6 has a negative focal length as a whole. The seventh lens E7 is a positive meniscus lens formed convex to the object side, the eighth lens E8 is a negative meniscus lens formed convex to the object side, the ninth lens E9 is a positive lens formed of a biconvex lens, The tenth lens E10 is a negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. Thus, the third lens group G3 constituted by the seventh lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive meniscus lens convexly formed on the object side, and only the twelfth lens E12 forms a fourth lens group G4 having a positive focal length. The diaphragm FA disposed between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable.
[0058]
The optical filter OF disposed on the image plane side of the twelfth lens E12, which is the fourth lens group G4, is held integrally with the fourth lens group G4 and has various optical filtering functions. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface, the nineteenth surface which is the image surface side of the eleventh lens E11 located closest to the image surface side of the third lens group G3, and the object side of the twelfth lens E12 constituting the fourth lens group G4 Each of the twentieth surfaces is an aspheric surface.
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3 that performs the action moves from the image plane side to the object side.
In the third embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 4.95 to 14.85 and F = 2.97 to 4.13, respectively, by zooming. , Ω = 44.45 to 17.07. The optical characteristics associated with each optical surface and optical element are as follows.
[0059]
[Table 5]
optical properties

[0060]
In Table 5, the sixth, twelfth, nineteenth, and twentieth optical surfaces described as “(aspherical surface)” are aspherical surfaces, and the above-described equation (1) for each aspherical surface is used. Are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 7.68143 × 10^-5
A₆= −5.557879 × 10^-7
A₈= 3.43461 × 10^-9
A₁₀= −1.27675 × 10^-11
Aspheric surface: 12th surface
K = 0
A₄= −5.990244 × 10^-5
A₆= −2.26307 × 10^-8
A₈= 3.999618 × 10^-8
A₁₀= -1.41064 x 10^-9
[0061]
Aspheric surface: 19th surface
K = 0
A₄= 4.189090 × 10^-4
A₆= 6.31024 × 10^-6
A₈= -1.60998 × 10^-7
A₁₀= 9.661896 × 10^-9
Aspheric surface: 20th surface
K = 0
A₄= −4.83239 × 10^-5
A₆= 4.20481 × 10^-6
A₈= −3.49807 × 10^-7
A₁₀= 8.93436 × 10^-9
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0062]
[Table 6]
Variable interval

[0063]
The numerical values related to the above-described conditional expressions of the present invention in the third embodiment are as follows, and are values within or close to the range of each conditional expression.
Conditional expression
N_C2(N_15-16) = 1.48749
ν_C2(Ν_15-16) = 70.44
N_C1(N_14-15) = 1.75520
ν_C1(Ν_14-15) = 27.53
N_C3(N_16-17) = 1.67270
ν_C3(Ν_16-17) = 32.17
R_C2/ R_C4(R_Fifteen/ R₁₇) = 0.249 (= 7.230 / 28.990)
[0064]
[Fourth embodiment]
FIG. 4 shows a configuration of an optical system of a zoom lens according to a fourth embodiment of the present invention.
The zoom lens shown in FIG. 4 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. Note that, as described above, each reference numeral for FIG. 4 is independently used for each embodiment, and even if a common reference numeral is assigned, it is not necessarily a common configuration in other embodiments.
[0065]
4, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens are sequentially arranged from the object side such as a subject. E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and an optical filter OF, which are arranged in this order, behind the optical filter OF having various optical filtering functions. Is imaged.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is also formed convex on the object side. The first lens E1 and the second lens E2 are tightly cemented two-element cemented lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole.
[0066]
The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, and the sixth lens E6 is a positive lens composed of a biconvex lens. The fifth lens E5 and the sixth lens E6 is a double cemented lens that is tightly cemented. The second lens group constituted by the fourth to sixth lenses E4 to E6 has a negative focal length as a whole. The seventh lens E7 is a positive meniscus lens formed convex to the object side, the eighth lens E8 is a negative meniscus lens formed convex to the object side, the ninth lens E9 is a positive lens formed of a biconvex lens, The tenth lens E10 is a negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. Thus, the third lens group G3 constituted by the seventh lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive meniscus lens convexly formed on the object side, and only the twelfth lens E12 forms a fourth lens group G4 having a positive focal length.
[0067]
The diaphragm FA disposed between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable. The optical filter OF disposed on the image plane side of the twelfth lens E12, which is the fourth lens group G4, is held integrally with the fourth lens group G4 and has various optical filtering functions. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface, the nineteenth surface which is the image surface side of the eleventh lens E11 located closest to the image surface side of the third lens group G3, and the object side of the twelfth lens E12 constituting the fourth lens group G4 Each of the twentieth surfaces is an aspheric surface.
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3, which acts, moves from the image plane side to the object side, and the fourth lens group G4 does not move.
In the fourth embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 5.80 to 29.00 and F = 3.01 to 4.58, respectively, due to zooming. , Ω = 40.16 to 8.91. The optical characteristics associated with each optical surface and optical element are as follows.
[0068]
[Table 7]
optical properties

[0069]
In Table 7, each of the sixth, twelfth, nineteenth, and twentieth optical surfaces described as “(aspheric surface)” is an aspheric surface. Such parameters are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 8.112716 × 10^-5
A₆= -4.737737 × 10^-7
A₈= 2.32995 × 10^-9
A₁₀= −6.622294 × 10^-12
Aspheric surface: 12th surface
K = 0
A₄= −4.04940 × 10^-5
A₆= 1.08387 × 10^-7
A₈= 2.110711 × 10^-9
A₁₀= −9.7144 × 10^-11
[0070]
Aspheric surface: 19th surface
K = 0
A₄= 2.66425 × 10^-4
A₆= 2.83525 × 10^-6
A₈= 6.42161 × 10^-9
A₁₀= 1.40725 × 10^-10
Aspheric surface: 20th surface
K = 0
A₄= −5.642236 × 10^-5
A₆= -2.44622 x 10^-7
A₈= −1.02479 × 10^-8
A₁₀= −1.58903 × 10^-10
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0071]
[Table 8]
Variable interval

[0072]
The numerical values of the above-described conditional expressions of the present invention in the fourth embodiment are as follows, and are within the ranges of the conditional expressions.
Conditional expression
N_C2(N_15-16) = 1.48749
ν_C2(Ν_15-16) = 70.44
N_C1(N_14-15) = 1.75050
ν_C1(Ν_14-15) = 35.04
N_C3(N_16-17) = 1.69895
ν_C3(Ν_16-17) = 30.05
R_C2/ R_C4(R_Fifteen/ R₁₇) = 0.975 (= 10.996 / 11.275)
[0073]
[Fifth embodiment]
FIG. 5 shows a configuration of an optical system of a zoom lens according to a fifth embodiment of the present invention.
The zoom lens shown in FIG. 5 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and a stop FA are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. Note that, as described above, each reference numeral for FIG. 5 is independently used for each embodiment, and even if a common reference numeral is assigned, it does not necessarily have a common configuration with other embodiments.
[0074]
In FIG. 5, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens, for example, sequentially from the object side such as a subject. E7, eighth lens E8, ninth lens E9, tenth lens E10, eleventh lens E11, and twelfth lens E12 are arranged in that order, and an image is formed behind the twelfth lens E12.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is also formed convex on the object side. The first lens E1 and the second lens E2 are closely cemented two-element lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole. The fourth lens E4 is a negative meniscus lens formed convex on the object side, the fifth lens E5 is a negative lens formed of a biconcave lens, and the sixth lens E6 is a positive lens formed of a biconvex lens. The fifth lens E5 and the sixth lens E6 are two cemented lenses that are tightly cemented, and the second lens group including the fourth lens E4 to the sixth lens E6 has a negative focal length as a whole.
[0075]
The seventh lens E7 is a positive lens formed of a biconvex lens, the eighth lens E8 is a negative meniscus lens formed convex on the object side, the ninth lens E9 is a positive lens formed of a biconvex lens, and the tenth lens E10 is The negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. The third lens group G3 including the lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive meniscus lens convexly formed on the object side, and only the twelfth lens E12 forms a fourth lens group G4 having a positive focal length. The diaphragm FA disposed between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface and the twentieth surface which is the object-side surface of the twelfth lens E12 forming the fourth lens unit G4 are aspherical.
[0076]
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3 that performs the function moves from the image plane side to the object side, and the fourth lens group G4 is fixed in this case, but mainly moves the second lens group and the third lens group. Can be moved to correct the movement of the image plane due to the
In the fifth embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 5.80 to 17.30 and F = 2.81 to 4.20 due to zooming, respectively. , Ω = 40.90 to 14.70. The optical characteristics associated with each optical surface and optical element are as follows.
[0077]
[Table 9]
optical properties

[0078]
In Table 9, each of the sixth, twelfth, and twentieth optical surfaces described as “(aspheric surface)” is an aspheric surface, and the parameter of each aspheric surface according to Equation (1) described above is Is as follows.
Aspheric surface: 6th surface
K = 0
A₄= 5.23222 × 10^-5
A₆= −1.06487 × 10^-6
A₈= 1.53041 × 10^-8
A₁₀= −1.05107 × 10^-10
[0079]
Aspheric surface: 12th surface
K = 0
A₄= -2.36271 × 10^-4
A₆= 8.2279 × 10^-7
A₈= -2.66532 × 10^-8
A₁₀= 1.51637 × 10^-10
Aspheric surface: 20th surface
K = 0
A₄= -2.13837 × 10^-4
A₆= 1.02617 × 10^-5
A₈= −4.99681 × 10^-7
A₁₀= 1.333335 × 10^-8
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0080]
[Table 10]
Variable interval

[0081]
The numerical values of the above-described conditional expressions of the present invention in the fifth embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
N_C2(N_15-16) = 1.51680
ν_C2(Ν_15-16) = 64.20
N_C1(N_14-15) = 1.71736
ν_C1(Ν_14-15) = 29.50
N_C3(N_16-17) = 1.75520
ν_C3(Ν_16-17) = 27.53
R_C2/ R_C4(R_Fifteen/ R₁₇) = 1.116 (= 7.087 / 6.348)
[0082]
[Sixth embodiment]
FIG. 6 shows a configuration of an optical system of a zoom lens according to a sixth embodiment of the present invention.
The zoom lens shown in FIG. 6 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the sixth lens E6 constitute a second lens group G2, and the seventh lens E7 to an eleventh lens. The lens E11 forms a third lens group G3, and the twelfth lens E12 forms a fourth lens group G4. Each of the lens groups is supported by a common support frame or the like appropriate for each lens group. It operates integrally for each lens group. Note that, as described above, each reference numeral for FIG. 6 is independently used for each embodiment, and even if a common reference numeral is assigned, it does not necessarily have a common configuration with other embodiments.
[0083]
In FIG. 6, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, an aperture FA, and a seventh lens, for example, sequentially from the object side such as a subject. E7, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, and an optical filter OF, which are arranged in this order, behind the optical filter OF having various optical filtering functions. Is imaged.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is also formed convex on the object side. The first lens E1 and the second lens E2 are closely cemented two-element lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole. The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, and the sixth lens E6 is a positive lens composed of a biconvex lens. The fifth lens E5 and the sixth lens E6 is a double cemented lens that is tightly cemented. The second lens group constituted by the fourth to sixth lenses E4 to E6 has a negative focal length as a whole.
[0084]
The seventh lens E7 is a positive lens formed of a biconvex lens, the eighth lens E8 is a negative meniscus lens formed convex on the object side, the ninth lens E9 is a positive lens formed of a biconvex lens, and the tenth lens E10 is The negative lens composed of a biconcave lens, the eleventh lens E11 is a positive lens composed of a biconvex lens, and the eighth lens E8 to the tenth lens E10 are three cemented lenses that are tightly cemented. The third lens group G3 including the lens E7 to the eleventh lens E11 has a positive focal length as a whole. The twelfth lens E12 is a positive lens formed of a biconvex lens, and the twelfth lens E12 alone forms a fourth lens group G4 having a positive focal length. The diaphragm FA disposed between the second lens group G2 and the third lens group G3 makes the distance between the second lens group G2 and the third lens group G3 variable. The optical filter OF disposed on the image plane side of the twelfth lens E12, which is the fourth lens group G4, is held integrally with the fourth lens group G4 and has various optical filtering functions. The sixth surface which is the object-side surface of the fourth lens E4 located closest to the object in the second lens group G2, and the object-side surface of the seventh lens E7 located closest to the object in the third lens group G3. The twelfth surface and the twentieth surface which is the object-side surface of the twelfth lens E12 forming the fourth lens unit G4 are aspherical.
[0085]
With zooming from the wide-angle end, that is, the short focal end, to the telephoto end, that is, the long focal end, the second lens group G2 moves from the object side to the image plane side, and mainly performs zooming and image plane correction. The third lens group G3 that acts is moved from the image plane side to the object side, and the fourth lens group G4 is fixed in this case, but mainly moves the second lens group and the third lens group. It may be moved so as to correct the accompanying image plane movement.
In the sixth embodiment, the focal length f, the F number F, and the half angle of view ω of the entire system are f = 5.80 to 17.30 and F = 2.89 to 4.02, respectively, by zooming. , Ω = 39.93 to 14.65. The optical characteristics associated with each optical surface and optical element are as follows.
[0086]
[Table 11]
optical properties

[0087]
In Table 11, the sixth, twelfth, and twentieth optical surfaces described as “(aspherical surface)” are aspherical surfaces, and the parameters of each aspherical surface according to Equation (1) described above are as follows: It is as follows.
Aspheric surface: 6th surface
K = 0
A₄= 1.10558 × 10^-4
A₆= −1.01970 × 10^-6
A₈= 7.93490 × 10^-9
A₁₀= -3.49749 × 10^-11
Aspheric surface: 12th surface
K = 0
A₄= -7.70888 × 10^-5
A₆= 2.55732 × 10^-7
A₈= −7.944450 × 10^-10
A₁₀= −6.13339 × 10^-11
[0088]
Aspheric surface: 20th surface
K = 0
A₄= −1.76923 × 10^-5
A₆= 3.83822 × 10^-7
A₈= −8.171688 × 10^-9
A₁₀= 1.40087 × 10^-10
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second group optical system G2 and the stop FA₁₀, The distance D between the stop FA and the third lens group G3₁₁And the distance D between the third lens group G3 and the fourth lens group G4₁₉Are variable, and these variable intervals D₅, D₁₀, D₁₁, D₁₉Is changed as shown in the following table with zooming.
[0089]
[Table 12]
Variable interval

[0090]
The numerical values of the above-described conditional expressions of the present invention in the sixth embodiment are as follows, and are values within the range of each conditional expression.
Conditional expression
N_C2(N_15-16) = 1.51680
ν_C2(Ν_15-16) = 64.20
N_C1(N_14-15) = 1.69895
ν_C1(Ν_14-15) = 30.05
N_C3(N_16-17) = 1.75520
ν_C3(Ν_16-17) = 27.53
R_C2/ R_C4(R_Fifteen/ R₁₇) = 0.890 (= 8.100 / 9.105)
FIG. 7 is an aberration curve diagram at the short focal length end of the zoom lens according to the first embodiment, FIG. 8 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the first embodiment, and FIG. FIG. 3 is an aberration curve diagram at a long focal end of the zoom lens according to the first embodiment.
[0091]
10 is an aberration curve diagram at the short focal length end of the zoom lens according to the second embodiment, FIG. 11 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the second embodiment, and FIG. FIG. 8 is an aberration curve diagram at the long focal end of the zoom lens according to Example 2; Similarly, FIG. 13 is an aberration curve diagram at the short focal length end of the zoom lens according to the third embodiment, FIG. 14 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the third embodiment, and FIG. FIG. 10 is an aberration curve diagram at the long focal end of the zoom lens according to Example 3; 16 is an aberration curve diagram at the short focal length end of the zoom lens according to the fourth embodiment, FIG. 17 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the fourth embodiment, and FIG. FIG. 5 is an aberration curve diagram at a long focal end of the zoom lens according to the example. FIG. 19 is an aberration curve diagram at the short focal length end of the zoom lens according to the fifth embodiment, FIG. 20 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the fifth embodiment, and FIG. FIG. 5 is an aberration curve diagram at a long focal end of the zoom lens according to the example.
[0092]
FIG. 22 is an aberration curve diagram at the short focal length end of the zoom lens according to the sixth embodiment, FIG. 23 is an aberration curve diagram at an intermediate focal length of the zoom lens according to the sixth embodiment, and FIG. FIG. 5 is an aberration curve diagram at a long focal end of the zoom lens according to the example. 7 to 24, the solid line in the spherical aberration diagram represents the spherical aberration, the broken line represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional. From these aberration curve diagrams, it can be seen that good characteristics are obtained by the above-described embodiments.
If a camera is configured by using the zoom lens described in each of the embodiments as a photographing lens, a camera having a small size, a wide angle of view, and high image quality can be realized. When the portable information terminal device is configured by using as a photographing lens of the camera function unit, a portable information terminal device having a small size, a wide angle of view, and a high image quality camera function can be realized.
[0093]
【The invention's effect】
As described above, according to the present invention, a zoom lens having a sufficiently small size, a wide angle of view, and high performance, and having a resolution corresponding to an image sensor of 3 to 5 million pixels, and using the zoom lens A camera and a portable information terminal device can be provided.
That is, according to the zoom lens of the first aspect of the present invention, from the object side to the image plane side, the first lens group that has a positive refractive power and does not move with zooming, and A second lens group having power and moving from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and an image plane having a positive refractive power and moving from the wide-angle end to the telephoto end with zooming A third lens group that moves from the side to the object side, and a fourth lens group that has a positive refractive power and does not move with zooming, wherein the third lens group includes: By having a three cemented lens composed of a negative lens, a positive lens and a negative lens, it is sufficiently compact, has a wide angle of view, has high performance, and has a resolution corresponding to an image sensor of 3 to 5 million pixels. A zoom lens can be provided, especially It achieves high third lens group having difference correction capability, and with minimal aberration fluctuation due to zooming, aberrations, especially with sufficiently reduced lateral chromatic aberration, it is possible to achieve high resolution.
[0094]
According to the zoom lens of the second aspect of the present invention, in the zoom lens of the first aspect, of the three cemented lenses, the negative lens disposed closest to the object has a concave surface facing the image plane side. With a negative meniscus lens having a concave meniscus shape, it is possible, in particular, to perform more sufficient aberration correction, particularly correction of spherical aberration, coma, and astigmatism.
According to the zoom lens of the third aspect of the present invention, in the zoom lens according to the first aspect, among the three cemented lenses, the negative lens disposed closest to the image plane has a concave surface on the image plane side. By using a negative lens directed toward the lens, it is possible to perform, in particular, more sufficient aberration correction, particularly correction of spherical aberration, coma, and astigmatism.
According to the zoom lens of the fourth aspect of the present invention, in the zoom lens according to the first aspect, the refractive index and the Abbe number of the positive lens disposed in the middle of the three cemented lenses are each N_C2And ν_C2Then the conditional expression:
1.45 <N_C2<1.52
68 <ν_C2<85
In particular, satisfactory chromatic aberration correction can be achieved and the cost can be suppressed.
[0095]
According to the zoom lens of the fifth aspect of the present invention, in the zoom lens of the fourth aspect, the refractive index and the Abbe number of the negative lens disposed closest to the object side of the three cemented lens are set to N, respectively._C1And ν_C1And the refractive index and Abbe number of the negative lens arranged closest to the image plane side of the three cemented lens are respectively N_C3And ν_C3Then the conditional expression:
1.60 <N_C1<1.95
20 <ν_C1<40
1.60 <N_C3<1.95
20 <ν_C3<40
Is satisfied, it is possible to favorably correct lateral chromatic aberration, and in particular, it is possible to reduce lateral chromatic aberration at the short focal length end.
[0096]
According to the zoom lens of the sixth aspect of the present invention, in the zoom lens according to the first aspect, the radius of curvature of the cemented surface on the object side of the three cemented lens in the third lens group is R._C2And the radius of curvature of the image-side surface of the three cemented lenses in the third lens group is R_C4Then, the conditional expression:
0.25 <(R_C2/ R_C4) <1.25
In particular, it is possible to further improve monochromatic chromatic aberration.
According to the zoom lens of the present invention, from the object side to the image plane side, the first lens group which has a positive refractive power and does not move with zooming, and has a negative refractive power. And a second lens group that moves from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and the image side that has a positive refractive power and moves from the wide-angle end to the telephoto end with zooming And a fourth lens group having a positive refracting power and not moving with zooming, is disposed in a zoom lens, wherein the third lens group has a negative refractive power. By having a three-element cemented lens composed of a lens, a positive lens, and a negative lens and at least one positive element disposed on each of the object side and the image plane side of the three-element cemented lens, it is sufficiently small and compact. High performance with wide angle of view, 3,000,000 to 5 It is possible to provide a zoom lens having a resolving power corresponding to an image sensor of 100,000 pixels, and in particular, to improve the balance of the arrangement of the refractive power and prevent the occurrence of excessive aberration on one lens surface, Deterioration in performance due to manufacturing errors such as eccentricity can be suppressed to a small level.
[0097]
According to a zoom lens of an eighth aspect of the present invention, in the zoom lens according to the seventh aspect, at least one of the positive lenses disposed on the object side and the image plane side of the three cemented lens. Since one of the lenses is an aspherical positive lens having an aspherical surface, in particular, spherical aberration and coma or spherical aberration, coma and astigmatism are effectively corrected, and the third lens group is reduced in size. In particular, the total length can be reduced.
[0098]
According to the zoom lens of the ninth aspect of the present invention, from the object side to the image plane side, the first lens group which has a positive refractive power and does not move with zooming, and a negative refractive power And a second lens group that moves from the object side to the image plane side from the wide-angle end to the telephoto end with zooming, and the image side that has a positive refractive power and moves from the wide-angle end to the telephoto end with zooming And a fourth lens group having a positive refracting power and appropriately moving with zooming is disposed, wherein the third lens group includes: By having a three cemented lens composed of a negative lens, a positive lens and a negative lens, it is sufficiently compact, has a wide angle of view, has high performance, and has a resolution corresponding to an image sensor of 3 to 5 million pixels. A zoom lens can be provided. By the associated movement of the third lens group's group, it is possible to further high zoom ratio, a wide angle of view and miniaturization.
[0099]
According to the invention described in claim 10 of the present invention, by including the zoom lens according to any one of claims 1 to 9 as a photographing optical system of a camera, Equipped with a high-performance photographic optical system that is sufficiently small and has a wide angle of view, while minimizing aberration fluctuation due to zooming in the zoom lens as a photographic optical system, reducing each aberration, achieving high resolution. Camera can be provided.
According to the invention described in claim 11 of the present invention, by including the zoom lens described in any one of claims 1 to 9 as an imaging optical system of a camera function unit, In particular, it suppresses aberration fluctuation due to zooming in a zoom lens as a photographing optical system of the photographing function unit, reduces each aberration, achieves high resolution, and is high performance while being sufficiently compact and wide angle of view The portable information terminal device provided with the photographing optical system in the camera function unit can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an optical system of a first example of a zoom lens according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration of an optical system of a second example of the zoom lens according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating a configuration of an optical system of a third example of the zoom lens according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a configuration of an optical system of a fourth example of the zoom lens according to the first embodiment of the present invention.
FIG. 5 is a schematic diagram illustrating a configuration of an optical system of a fifth example of the zoom lens according to the first embodiment of the present invention.
FIG. 6 is a schematic diagram illustrating a configuration of an optical system of Example 6 of the zoom lens according to Embodiment 1 of the present invention;
FIG. 7 is an aberration curve diagram showing aberration characteristics at the short focal length end of the optical system of the first example shown in FIG. 1 of the zoom lens according to the first embodiment of the present invention.
8 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of the first example shown in FIG. 1 of the zoom lens according to the first embodiment of the present invention.
FIG. 9 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system according to the first example shown in FIG.
FIG. 10 is an aberration curve diagram showing aberration characteristics at the short focal length end of the optical system according to the second example shown in FIG. 2 of the zoom lens according to the first embodiment of the present invention.
11 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at an intermediate focal length of the optical system of Example 2 shown in FIG. 2;
12 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system according to the second example shown in FIG. 2. FIG.
13 is an aberration curve diagram showing an aberration characteristic at a short focal length end of the optical system according to the third example shown in FIG. 3 of the zoom lens according to the first embodiment of the present invention.
14 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 3 shown in FIG. 3 of the zoom lens according to the first embodiment of the present invention.
15 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system of Example 3 shown in FIG.
16 is an aberration curve diagram showing an aberration characteristic at a short focal length end of the optical system of Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
17 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
18 is an aberration curve diagram showing an aberration characteristic at a long focal end of an optical system according to Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
19 is an aberration curve diagram showing an aberration characteristic at a short focal length end of the optical system of Example 5 shown in FIG. 5 of the zoom lens according to the first embodiment of the present invention.
20 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 5 shown in FIG. 5 of the zoom lens according to the first embodiment of the present invention.
21 is an aberration curve diagram showing an aberration characteristic at a long focal end of an optical system according to Example 5 shown in FIG. 5 of the zoom lens according to the first embodiment of the present invention.
22 is an aberration curve diagram showing an aberration characteristic at a short focal length end of an optical system according to Example 6 shown in FIG. 6 of the zoom lens according to the first embodiment of the present invention.
FIG. 23 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 6 shown in FIG. 6 of the zoom lens according to the first embodiment of the present invention.
24 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system of Example 6 shown in FIG. 6.
[Explanation of symbols]
G1 First lens group
G2 Second lens group
G3 Third lens group
G4 4th lens group
FA aperture
OF optical filter
E1 First lens
E2 Second lens
E3 Third lens
E4 4th lens
E5 Fifth lens
E6 6th lens
E7 7th lens
E8 8th lens
E9 9th lens
E10 10th lens
E11 eleventh lens
E12 12th lens

Claims (11)

A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side toward and a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and not moving with zooming.
The zoom lens according to claim 1, wherein the third lens group includes a triplet lens including a negative lens, a positive lens, and a negative lens. 2. The zoom lens according to claim 1, wherein, among the three cemented lenses, the negative lens disposed closest to the object is a negative meniscus lens having a meniscus shape having a concave surface facing the image surface side. 3. . 2. The zoom lens according to claim 1, wherein the negative lens disposed closest to the image plane among the three cemented lenses is a negative lens having a concave surface facing the image plane. 3. Assuming that the refractive index and Abbe number of the positive lens disposed in the middle of the three cemented lenses are N _C2 and ν _C2 , respectively, a conditional expression:
1.45 < _NC2 <1.52
68 <ν _C2 <85
The zoom lens according to claim 1, wherein the following condition is satisfied. The refractive index of the negative lens disposed on the most object side of the cemented triplet and the Abbe number, respectively, and N _C1 and [nu _C1, the negatively and is disposed on the most image side of the cemented triplet the refractive index of the lens and the Abbe number, _{respectively,} when the _{N C3} and [nu _C3, condition:
1.60 < _NC1 <1.95
20 <ν _C1 <40
1.60 < _NC3 <1.95
20 <ν _C3 <40
The zoom lens according to claim 4, wherein the following condition is satisfied. The radius of curvature of the cemented surface on the object side of the triplet lens of the third lens group is R _C2, and the radius of curvature of the image side of the triplet lens of the third lens group is R _C4. Then the conditional expression:
0.25 <( _RC2 / _RC4 ) <1.25
The zoom lens according to claim 1, wherein the following condition is satisfied. A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side toward and a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and not moving with zooming.
The third lens group includes:
A three cemented lens composed of a negative lens, a positive lens, and a negative lens;
A zoom lens having at least one positive lens disposed on each of the object side and the image plane side of the triplet lens. 8. The positive lens according to claim 7, wherein at least one of the positive lenses disposed on the object side and the image plane side of the three-element cemented lens is an aspheric positive lens having an aspheric surface. The described zoom lens. A first lens unit having a positive refractive power and not moving with zooming in order from the object side to the image plane side; and a wide-angle end to a telephoto end having negative refractive power and zooming along with zooming. A second lens group that moves from the object side to the image plane side toward and a third lens group that has a positive refractive power and moves from the image plane side to the object side from the wide-angle end to the telephoto end with zooming, And a fourth lens group having a refractive power of and moving appropriately with zooming.
The zoom lens according to claim 1, wherein the third lens group includes a triplet lens including a negative lens, a positive lens, and a negative lens. A camera comprising the zoom lens according to any one of claims 1 to 9 as a photographing optical system. A portable information terminal device comprising the zoom lens according to claim 1 as a photographing optical system of a camera function unit.

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