JP2004157195A - Zoom lens, camera and personal digital assistant device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a zoom lens made very compact, capable of obtaining a wide viewing angle and having high performance and sufficient resolving power. <P>SOLUTION: The zoom lens is constituted by arranging a 1st group optical system G1 having negative power, a 2nd group optical system G2 having positive power and a 3rd group optical system G3 having positive power successively from an object side, and is provided with a diaphragm FA integrally moving to the object side of the optical system G2. In the case of varying power from a short focal end to a long focal end, the optical systems G1, G2 and G3 are moved so that space between the optical systems G1 and G2 may be smaller and smaller and space between the optical systems G2 and G3 may be larger and larger. The optical system G2 consists of four lenses of three groups, where a positive lens E4, a negative meniscus lens E5, a positive meniscus lens E6 bonded to the lens E5 and a positive lens E7 are arrayed successively from the object side. Assuming that the refractive index of the lens E5 is N<SB>22</SB>and the refractive index of the lens E6 is N<SB>23</SB>, they satisfy 0.15<(N<SB>22</SB>-N<SB>23</SB>)<0.40. <P>COPYRIGHT: (C)2004,JPO

Description

【００６４】
〔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、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群光学系Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２群光学系Ｇ２を構成し、第８レンズＥ８は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図１には、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の移動軌跡を模式的に矢印で示している。また、図１には、各光学面の面番号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共通の構成ではない。
【００６５】
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、絞りＦＡ、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。
【００６６】
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負メニスカスレンズ、そして第３レンズＥ３は、物体側を凸面とした正レンズ（平凸レンズ）であり、これら第１レンズＥ１〜第３レンズＥ３により構成する第１群光学系Ｇ１は、全体として負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正メニスカスレンズ、第５レンズＥ５は、物体側に凸に形成された負メニスカスレンズ、第６レンズＥ６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７レンズＥ７は、正レンズ（両凸レンズ）で、第５レンズＥ５と第６レンズＥ６は、接合されており、これら３群４枚構成の第４レンズＥ４〜第７レンズＥ７により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第８レンズＥ８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８レンズＥ８のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【００６７】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【００６８】
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＝５．９３〜１６．７８、Ｆ＝２．５７〜４．３７、そしてω＝３９．４２〜１５．６２の範囲で変化する。各光学面の特性は、次表の通りである。
【００６９】
【表１】
光学特性

【００７０】
表１において面番号にアスタリスク「＊」を付した第４面、第８面、第１４面および第１５面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第４面
Ｋ＝０．０，Ａ_４＝−２．７８４９３×１０^−４，Ａ_６＝−４．５７２５２×１０^−６，Ａ_８＝２．８５３９７×１０^−７，Ａ_１０＝−１．９０６９５×１０^−８，Ａ_１２＝５．０７２８８×１０^−１０，Ａ_１４＝−１．９０１９４×１０^−１２，Ａ_１６＝−１．６８２４１×１０^−１３，Ａ_１８＝２．３１３７０×１０^−１５
非球面：第８面
Ｋ＝０．０，Ａ_４＝−８．５４５６９×１０^−５，Ａ_６＝−３．６０１８０×１０^−７，Ａ_８＝−３．６３６４８×１０^−８，Ａ_１０＝９．６１３３５×１０^−１０
非球面：第１４面
Ｋ＝０．０，Ａ_４＝１．６７１１２×１０^−４，Ａ_６＝６．２９４７８×１０^−６，Ａ_８＝−３．９６３８３×１０^−７，Ａ_１０＝２．１４２２２×１０^−８非球面：第１５面
Ｋ＝０．０，Ａ_４＝−１．５１１２２×１０^−５，Ａ_６＝２．９４７０９×１０^−６，Ａ_８＝−１．１６２８１×１０^−７，Ａ_１０＝２．０５０７１×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【００７１】
【表２】
可変間隔

【００７２】
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、各条件式の範囲内である。
条件式数値
（Ｎ_２２−Ｎ_２３）＝０．３５９
（ν_２３ −ν_２２ ）＝４６．７
（（１／ｒ_２１Ｆ ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．７９
（Ｌ_ＰＮ／Ｌ_２）＝０．５８９
〔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、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群光学系Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２群光学系Ｇ２を構成し、第８レンズＥ８は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図２にも、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の概略的な移動軌跡を模式的に矢印で示している。また、図２には、各光学面の面番号も付して示している。上述したように図２に対する各参照符号も、他の実施例とは独立に用いている。
【００７３】
図２においても、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、絞りＦＡ、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。
【００７４】
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負メニスカスレンズ、そして第３レンズＥ３は、物体側を曲率の大きな凸面とした正レンズ（両凸レンズ）であり、これら第１レンズＥ１〜第３レンズＥ３により構成する第１群光学系Ｇ１は、全体として負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正メニスカスレンズ、第５レンズＥ５は、物体側に凸に形成された負メニスカスレンズ、第６レンズＥ６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７レンズＥ７は、正レンズ（両凸レンズ）で、第５レンズＥ５と第６レンズＥ６は、接合されており、これら３群４枚構成の第４レンズＥ４〜第７レンズＥ７により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第８レンズＥ８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８レンズＥ８のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【００７５】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【００７６】
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＝５．９７〜１６．８６、Ｆ＝２．５８〜４．３４、そしてω＝３９．２１〜１５．５４の範囲で変化する。各光学面の特性は、次表の通りである。
【００７７】
【表３】
光学特性

【００７８】
表３において面番号にアスタリスク「＊」を付した第４面、第８面、第１４面および第１５面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第４面
Ｋ＝０．０，Ａ_４＝−３．６５７７４×１０^−４，Ａ_６＝−６．９８０６３×１０^−６，Ａ_８＝３．３１２３９×１０^−７，Ａ_１０＝−２．１０２２３×１０^−８，Ａ_１２＝４．７５９５５×１０^−１０，Ａ_１４＝−１．５３４０７×１０^−１２，Ａ_１６＝−１．２６１１９×１０^−１３，Ａ_１８＝１．３８２３１×１０^−１５
非球面：第８面
Ｋ＝０．０，Ａ_４＝−８．２９４２２×１０^−５，Ａ_６＝−３．４９５４０×１０^−７，Ａ_８＝−４．２２０６０×１０^−８，Ａ_１０＝１．４３５２１×１０^−９
非球面：第１４面
Ｋ＝０．０，Ａ_４＝８．６２３３６×１０^−５，Ａ_６＝１．０８４０３×１０^−５，Ａ_８＝−１．１４４３２×１０^−６，Ａ_１０＝５．５５５００×１０^−８非球面：第１５面
Ｋ＝０．０，Ａ_４＝−１．４２７０８×１０^−５，Ａ_６＝３．１５２３５×１０^−６，Ａ_８＝−１．３３７２６×１０^−７，Ａ_１０＝２．５１３８７×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【００７９】
【表４】
可変間隔

【００８０】
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_２２−Ｎ_２３）＝０．３３０
（ν_２３−ν_２２）＝４０．４
（（１／ｒ_２１Ｆ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．７３
（Ｌ_ＰＮ／Ｌ_２）＝０．５９４
〔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、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群光学系Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２群光学系Ｇ２を構成し、第８レンズＥ８は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図３にも、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の概略的な移動軌跡を模式的に矢印で示している。また、図３には、各光学面の面番号も付して示している。上述したように図３に対する各参照符号も、他の実施例とは独立に用いている。
【００８１】
図３においても、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、絞りＦＡ、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。
【００８２】
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負メニスカスレンズ、そして第３レンズＥ３は、物体側を曲率の大きな凸面とした正レンズ（両凸レンズ）であり、これら第１レンズＥ１〜第３レンズＥ３により構成する第１群光学系Ｇ１は、全体として負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正メニスカスレンズ、第５レンズＥ５は、物体側に凸に形成された負メニスカスレンズ、第６レンズＥ６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７レンズＥ７は、正レンズ（両凸レンズ）で、第５レンズＥ５と第６レンズＥ６は、接合されており、これら３群４枚構成の第４レンズＥ４〜第７レンズＥ７により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第８レンズＥ８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８レンズＥ８のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【００８３】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【００８４】
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＝５．９７〜１６．８６、Ｆ＝２．６０〜４．３６、そしてω＝３９．２３〜１５．５３の範囲で変化する。各光学面の特性は、次表の通りである。
【００８５】
【表５】
光学特性

【００８６】
表５において面番号にアスタリスク「＊」を付した第４面、第８面、第１４面および第１５面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第４面
Ｋ＝０．０，Ａ_４＝−３．７４５２９×１０^−４，Ａ_６＝−７．０７１１１×１０^−６，Ａ_８＝３．３１０８０×１０^−７，Ａ_１０＝−２．１２５７８×１０^−８，Ａ_１２＝４．７２６９８×１０^−１０，Ａ_１４＝−１．４１４２９×１０^−１２，Ａ_１６＝−１．２３２８７×１０^−１３，Ａ_１８＝１．２６１２９×１０^−１５
非球面：第８面
Ｋ＝０．０，Ａ_４＝−９．２７２２１×１０^−５，Ａ_６＝−２．００６９１×１０^−７，Ａ_８＝−５．９９８１３×１０^−８，Ａ_１０＝１．９５３１１×１０^−９
非球面：第１４面
Ｋ＝０．０，Ａ_４＝１．１７５３３×１０^−４，Ａ_６＝１．２８９４１×１０^−５，Ａ_８＝−１．２６８８５×１０^−６，Ａ_１０＝６．０９６４５×１０^−８非球面：第１５面
Ｋ＝０．０，Ａ_４＝−１．９１３９７×１０^−５，Ａ_６＝３．８０３１３×１０^−６，Ａ_８＝−１．６７５１７×１０^−７，Ａ_１０＝３．０９０２８×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【００８７】
【表６】
可変間隔

【００８８】
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、各条件式の範囲内である。
条件式数値
（Ｎ_２２−Ｎ_２３）＝０．２８８
（ν_２３−ν_２２）＝３５．７
（（１／ｒ_２１Ｆ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．６６
（Ｌ_ＰＮ／Ｌ_２）＝０．５９０
〔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、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群光学系Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２群光学系Ｇ２を構成し、第８レンズＥ８は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図４にも、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の概略的な移動軌跡を模式的に矢印で示している。また、図４には、各光学面の面番号も付して示している。上述したように図４に対する各参照符号も、他の実施例とは独立に用いている。
【００８９】
図４においても、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、絞りＦＡ、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。
【００９０】
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負メニスカスレンズ、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、これら第１レンズＥ１〜第３レンズＥ３により構成する第１群光学系Ｇ１は、全体として負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正メニスカスレンズ、第５レンズＥ５は、物体側に凸に形成された負メニスカスレンズ、第６レンズＥ６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７レンズＥ７は、正レンズ（両凸レンズ）で、第５レンズＥ５と第６レンズＥ６は、接合されており、これら３群４枚構成の第４レンズＥ４〜第７レンズＥ７により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第８レンズＥ８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８レンズＥ８のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【００９１】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【００９２】
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＝５．９７〜１６．８８、Ｆ＝２．６８〜４．４２、そしてω＝３９．２０〜１５．５２の範囲で変化する。各光学面の特性は、次表の通りである。
【００９３】
【表７】
光学特性

【００９４】
表７において面番号にアスタリスク「＊」を付した第４面、第８面、第１４面および第１５面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第４面
Ｋ＝０．０，Ａ_４＝−３．５０２１３０×１０^−４，Ａ_６＝−８．４５４６１×１０^−６，Ａ_８＝３．８７１６６×１０^−７，Ａ_１０＝−２．３７７９１×１０^−８，Ａ_１２＝４．８６３８８×１０^−１０，Ａ_１４＝−３．７９１１２×１０^−１３，Ａ_１６＝−１．５２０４８×１０^−１３，Ａ_１８＝１．３２８８３×１０^−１５
非球面：第８面
Ｋ＝０．０，Ａ_４＝−９．８０６３８×１０^−５，Ａ_６＝−３．４４７７９×１０^−７，Ａ_８＝−４．４７５２２×１０^−８，Ａ_１０＝−８．３７４３０×１０^−１０
非球面：第１４面
Ｋ＝０．０，Ａ_４＝１．８３５３８×１０^−４，Ａ_６＝６．０９８１２×１０^−７，Ａ_８＝３．７２３６０×１０^−７，Ａ_１０＝−１．７０９３９×１０^−８非球面：第１５面
Ｋ＝０．０，Ａ_４＝−４．２１５１３×１０^−５，Ａ_６＝２．９５９４７×１０^−６，Ａ_８＝−１．２３５００×１０^−７，Ａ_１０＝２．３２３５１×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【００９５】
【表８】
可変間隔

【００９６】
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_２２−Ｎ_２３）＝０．３５９
（ν_２３−ν_２２）＝４６．７
（（１／ｒ_２１Ｆ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．９４
（Ｌ_ＰＮ／Ｌ_２）＝０．５５６
〔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、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４レンズＥ４は、第１群光学系Ｇ１を構成し、第５レンズＥ５〜第８レンズＥ８は、第２群光学系Ｇ２を構成し、第９レンズＥ９は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図５にも、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の概略的な移動軌跡を模式的に矢印で示している。また、図５には、各光学面の面番号も付して示している。上述したように図５に対する各参照符号も、他の実施例とは独立に用いている。
【００９７】
図５においても、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、絞りＦＡ、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。
【００９８】
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負メニスカスレンズ、第３レンズＥ３は、物体側に大きな曲率の凸面を向けた正レンズ（両凸レンズ）、そして第４レンズＥ４は、負レンズ（両凹レンズ）で、第３レンズＥ３と第４レンズＥ４は、接合されており、これら３群４枚構成の第１レンズＥ１〜第４レンズＥ４により構成する第１群光学系Ｇ１は、全体として負の焦点距離を呈する。第５レンズＥ５は、物体側に凸に形成された正メニスカスレンズ、第６レンズＥ６は、物体側に凸に形成された負メニスカスレンズ、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、そして第８レンズＥ８は、正レンズ（両凸レンズ）で、第６レンズＥ６と第７レンズＥ７は、接合されており、これら３群４枚構成の第５レンズＥ５〜第８レンズＥ８により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第９レンズＥ９は、物体側に大きな曲率の凸面を向けた正レンズ（両凸レンズ）であり、この第９レンズＥ９のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【００９９】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【０１００】
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＝５．９８〜１６．８９、Ｆ＝２．６２〜４．５１、そしてω＝３９．１８〜１５．５２の範囲で変化する。各光学面の特性は、次表の通りである。
【０１０１】
【表９】
光学特性

【０１０２】
表９において面番号にアスタリスク「＊」を付した第４面、第９面、第１５面および第１６面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第４面
Ｋ＝０．０，Ａ_４＝−３．１９９２３×１０^−４，Ａ_６＝−７．４９９９６×１０^−６，Ａ_８＝３．１１４８３×１０^−７，Ａ_１０＝−１．９０４２１×１０^−８，Ａ_１２＝３．９１２５８×１０^−１０，Ａ_１４＝−２．０１１０３×１０^−１２，Ａ_１６＝−５．４９００８×１０^−１４，Ａ_１８＝３．１９８７０×１０^−１６
非球面：第９面
Ｋ＝０．０，Ａ_４＝−９．６２１０５×１０^−５，Ａ_６＝−９．７８８７３×１０^−７，Ａ_８＝１．６２６２５×１０^−８，Ａ_１０＝−８．４６９０３×１０^−１０
非球面：第１５面
Ｋ＝０．０，Ａ_４＝１．６２６３９×１０^−４，Ａ_６＝２．９０７０５×１０^−５，Ａ_８＝−３．６８６１６×１０^−６，Ａ_１０＝２．０００６７×１０^−７非球面：第１６面
Ｋ＝０．０，Ａ_４＝−１．５７０４８×１０^−５，Ａ_６＝５．２４３２６×１０^−６，Ａ_８＝−２．３９６２０×１０^−７，Ａ_１０＝４．６２００３×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【０１０３】
【表１０】
可変間隔

【０１０４】
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_２２−Ｎ_２３）＝０．２０８
（ν_２３−ν_２２）＝３１．７
（（１／ｒ_２１Ｆ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．８６
（Ｌ_ＰＮ／Ｌ_２）＝０．４９８
〔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、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４レンズＥ４は、第１群光学系Ｇ１を構成し、第５レンズＥ５〜第８レンズＥ８は、第２群光学系Ｇ２を構成し、第９レンズＥ９は、第３群光学系Ｇ３を構成しており、それぞれ各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群毎に一体的に動作する。図５にも、ズーミング動作も把握できるようにするため、広角端である短焦点距離端から、中間焦点距離を経て、望遠端である長焦点距離端に至る各群の概略的な移動軌跡を模式的に矢印で示している。また、図６には、各光学面の面番号も付して示している。上述したように図６に対する各参照符号も、他の実施例とは独立に用いている。
【０１０５】
図６においても、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、絞りＦＡ、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。
【０１０６】
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負メニスカスレンズ、第３レンズＥ３は、物体側に凸に形成された負メニスカスレンズ、そして第４レンズＥ４は、物体側に凸に形成された正メニスカスレンズであり、これら４群４枚構成の第１レンズＥ１〜第４レンズＥ４により構成する第１群光学系Ｇ１は、全体として負の焦点距離を呈する。第５レンズＥ５は、物体側に凸に形成された正メニスカスレンズ、第６レンズＥ６は、物体側に凸に形成された負メニスカスレンズ、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、そして第８レンズＥ８は、正レンズ（両凸レンズ）で、第６レンズＥ６と第７レンズＥ７は、接合されており、これら３群４枚構成の第５レンズＥ５〜第８レンズＥ８により構成する第２群光学系Ｇ２は、全体として正の焦点距離を呈する。第９レンズＥ９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９レンズＥ９のみによって、正の焦点距離を有する第３群光学系Ｇ３を構成している。第２群光学系Ｇ２の物体側に配置された絞りＦＡは、第２群光学系Ｇ２と一体に動作する。
【０１０７】
短焦点端から長焦点端への変倍に際して、主として変倍機能を担う第２群光学系Ｇ２が像側から物体側へと単調に移動し、第１群光学系Ｇ１が変倍に伴う像面位置の変動を補正するように移動し、第３群光学系は、主として像面から射出瞳を遠ざけるために動作する。さらに具体的には、短焦点端から長焦点端への変倍に伴って、第１群光学系Ｇ１と第２群光学系Ｇ２の間隔を漸次小さくし、第２群光学系Ｇ２と第３群光学系Ｇ３の間隔を漸次大きくするように各群の光学系を移動させる。
【０１０８】
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＝５．９７〜１６．８８、Ｆ＝２．６３〜４．４５、そしてω＝３９．２０〜１５．５２の範囲で変化する。各光学面の特性は、次表の通りである。
【０１０９】
【表１１】
光学特性

【０１１０】
表９において面番号にアスタリスク「＊」を付した第６面、第１０面、第１６面および第１７面の各光学面が非球面であり、各非球面のパラメータは次の通りである。
非球面：第６面
Ｋ＝０．０，Ａ_４＝−３．７７０７７×１０^−４，Ａ_６＝−７．５７１１４×１０^−６，Ａ_８＝３．２４５５９×１０^−７，Ａ_１０＝−２．０６８４１×１０^−８，Ａ_１２＝４．４３８９８×１０^−１０，Ａ_１４＝−１．７２３６５×１０^−１２，Ａ_１６＝−９．２１０６８×１０^−１４，Ａ_１８＝７．６０６４２×１０^−１６
非球面：第１０面
Ｋ＝０．０，Ａ_４＝−９．００７５２×１０^−５，Ａ_６＝３．０９０５２×１０^−８，Ａ_８＝−７．１６５５６×１０^−８，Ａ_１０＝２．２５６１７×１０^−９
非球面：第１６面
Ｋ＝０．０，Ａ_４＝１．０２６７７×１０^−４，Ａ_６＝１．８２５５１×１０^−５，Ａ_８＝−１．９７０８３×１０^−６，Ａ_１０＝９．８１２７６×１０^−８非球面：第１７面
Ｋ＝０．０，Ａ_４＝−１．５９４６２×１０^−５，Ａ_６＝４．７６２１３×１０^−６，Ａ_８＝−２．２４９２９×１０^−７，Ａ_１０＝４．３０９４８×１０^−９
第１群光学系Ｇ１と第２群光学系Ｇ２に一体化された絞りＦＡとの間の間隔Ｄ_Ａ、第２群光学系Ｇ２と第３群光学系Ｇ３との間の間隔Ｄ_Ｂ、そして第３群光学系Ｇ３と光学フィルタＯＦとの間の間隔Ｄ_Ｃは、可変であり、これら可変間隔Ｄ_Ａ〜Ｄ_Ｃはズーミングに際して次表のように変化させられる。
【０１１１】
【表１２】
可変間隔

【０１１２】
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、各条件式の範囲内である。
条件式数値
（Ｎ_２２−Ｎ_２３）＝０．２５８
（ν_２３−ν_２２）＝３７．５
（（１／ｒ_２１Ｆ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）＝１．８０
（Ｌ_ＰＮ／Ｌ_２）＝０．５３８
図７〜図９は、上述した第１の実施例に係る図１に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図７は、短焦点端における収差曲線図、図８は、中間焦点距離における収差曲線図、そして図９は、長焦点端における収差曲線図である。各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
図１０〜図１２は、上述した第２の実施例に係る図２に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図１０は、短焦点端における収差曲線図、図１１は、中間焦点距離における収差曲線図、そして図１２は、長焦点端における収差曲線図である。この場合も、各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
【０１１３】
図１３〜図１５は、上述した第３の実施例に係る図３に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図１３は、短焦点端における収差曲線図、図１４は、中間焦点距離における収差曲線図、そして図１５は、長焦点端における収差曲線図である。この場合も、各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
図１６〜図１８は、上述した第４の実施例に係る図４に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図１６は、短焦点端における収差曲線図、図１７は、中間焦点距離における収差曲線図、そして図１８は、長焦点端における収差曲線図である。この場合も、各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
図１９〜図２１は、上述した第５の実施例に係る図５に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図１９は、短焦点端における収差曲線図、図２０は、中間焦点距離における収差曲線図、そして図２１は、長焦点端における収差曲線図である。この場合も、各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
そして図２２〜図２４は、上述した第６の実施例に係る図６に示したズームレンズおける球面収差、非点収差、歪曲収差およびコマ収差の収差曲線図を示しており、図２２は、短焦点端における収差曲線図、図２３は、中間焦点距離における収差曲線図、そして図２４は、長焦点端における収差曲線図である。この場合も、各収差曲線図中、球面収差図における破線は正弦条件をあらわし、非点収差図における実線はサジタル、破線はメリディオナルをあらわしている。
これらの図７〜図２４の収差曲線図によれば、上述した本発明の第１〜第６の実施例に係る図１〜図６に示した構成のズームレンズによれば、いずれも収差は良好に補正されあるいは抑制されていることがわかる。
【０１１４】
〔第７の実施例〕
次に、上述した第１〜第６の実施例に示されたような本発明に係るズームレンズを撮影光学系として採用してカメラを構成した本発明の第７の実施例について図２５〜図２７を参照して説明する。図２５は、物体、すなわち被写体側である前面側から見たカメラの外観を示す斜視図、図２６は、撮影者側である背面側から見たカメラの外観を示す斜視図であり、図２７は、カメラの機能構成を示すブロック図である。なお、ここでは、カメラについて説明しているが、いわゆるＰＤＡ（ｐｅｒｓｏｎａｌ ｄａｔａ ａｓｓｉｓｔａｎｔ）や携帯電話機等の携帯情報端末装置にカメラ機能を組み込んだものが、近年登場している。このような携帯情報端末装置も外観は若干異にするもののカメラと実質的に全く同様の機能・構成を含んでおり、このような携帯情報端末装置に本発明に係るズームレンズを採用してもよい。
【０１１５】
図２５および図２６に示すように、カメラは、撮影レンズ１０１、シャッタボタン１０２、ズームレバー１０３、ファインダ１０４、ストロボ１０５、液晶モニタ１０６、操作ボタン１０７、電源スイッチ１０８、メモリカードスロット１０９および通信カードスロット１１０等を備えている。さらに、図２７に示すように、カメラは、受光素子２０１、信号処理装置２０２、画像処理装置２０３、中央演算装置（ＣＰＵ）２０４、半導体メモリ２０５および通信カード等２０６も備えている。
カメラは、撮影レンズ１０１とＣＣＤ（電荷結合素子）撮像素子等のエリアセンサとしての受光素子２０１を有しており、撮影光学系である撮影レンズ１０１によって形成される撮影対象となる物体、つまり被写体、の像を受光素子２０１によって読み取るように構成されている。この撮影レンズ１０１としては、第１〜第６の実施例において説明したような本発明に係る（すなわち請求項１〜請求項９で定義される）ズームレンズを用いる（請求項１０および請求項１１に対応する）。
【０１１６】
受光素子２０１の出力は、中央演算装置２０４によって制御される信号処理装置２０２によって処理され、ディジタル画像情報に変換される。信号処理装置２０２によってディジタル化された画像情報は、やはり中央演算装置２０４によって制御される画像処理装置２０３において所定の画像処理が施された後、不揮発性メモリ等の半導体メモリ２０５に記録される。この場合、半導体メモリ２０５は、メモリカードスロット１０９に装填されたメモリカードでもよく、カメラ本体に内蔵された半導体メモリでもよい。液晶モニタ１０６には、撮影中の画像を表示することもできるし、半導体メモリ２０５に記録されている画像を表示することもできる。また、半導体メモリ２０５に記録した画像は、通信カードスロット１１０に装填した通信カード等２０６を介して外部へ送信することも可能である。
【０１１７】
撮影レンズ１０１は、カメラの携帯時には図２５の（ａ）に示すように沈胴状態にあってカメラのボディー内に埋没しており、ユーザが電源スイッチ１０８を操作して電源を投入すると、図２５の（ｂ）に示すように鏡胴が繰り出され、カメラのボディーから突出する構成とする。このとき、撮影レンズ１０１の鏡胴の内部では、ズームレンズを構成する各群の光学系は、例えば短焦点端の配置となっており、ズームレバー１０３を操作することによって、各群光学系の配置が変更されて、長焦点端への変倍動作を行うことができる。なお、好ましくは、ファインダ１０４も撮影レンズ１０１の画角の変化に連動して変倍する。
多くの場合、シャッタボタン１０２の半押し操作により、フォーカシングがなされる。先に述べた第１〜第６の実施例に示されたような負−正−正の３群で構成されるズームレンズにおけるフォーカシングは第１群光学系Ｇ１または第３群光学系Ｇ３の移動、あるいは、受光素子２０１の移動によって行うことができる。シャッタボタン１０２をさらに押し込み全押し状態とすると撮影が行なわれ、その後に上述した通りの処理がなされる。
【０１１８】
半導体メモリ２０５に記録した画像を液晶モニタ１０６に表示させたり、通信カード等２０６を介して外部へ送信させる際には、操作ボタン１０７を所定のごとく操作する。半導体メモリ２０５および通信カード等２０６は、メモリカードスロット１０９および通信カードスロット１１０等のような、それぞれ専用または汎用のスロットに装填して使用される。
上述のようなカメラまたは携帯情報端末装置には、既に述べた通り、第１〜第６の実施例に示されたようなズームレンズを撮影光学系として使用することができる。したがって、３００万画素〜６００万画素クラスの受光素子を使用した高画質で小型のカメラまたは携帯情報端末装置を達成することが可能となる。
【０１１９】
上述した実施例に基づいて本発明を各請求項に対応して整理する。本発明の請求項１によるズームレンズは、
物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、
短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、
前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、
【０１２０】
そして、前記第２群光学系の前記負メニスカスレンズの屈折率をＮ_２２、前記負メニスカスレンズに接合された前記正メニスカスレンズの屈折率をＮ_２３として、
条件式：
０．１５＜（Ｎ_２２−Ｎ_２３）＜０．４０
を満足する。
請求項１の構成によれば、充分に小型で且つ広画角でありながら、しかも高性能であり、３００万〜６００万画素の撮像素子に対応した解像力を有するズームレンズを提供することができ、その結果、小型で、広画角で、高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１２１】
本発明の請求項２によるズームレンズは、
請求項１のズームレンズにおいて、
前記第２群光学系における前記負メニスカスレンズのアッベ数をν_２２、該負メニスカスレンズに接合された前記正メニスカスレンズのアッベ数をν_２３として、
条件式：
２５＜（ν_２３ −ν_２２ ）＜５０
を満足する。
【０１２２】
請求項２の構成によれば、色収差を一層良好に補正した、高性能なズームレンズを提供することができ、その結果、一層高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１２３】
本発明の請求項３によるズームレンズは、
請求項１または請求項２のズームレンズにおいて、
前記第２群光学系における最も物体側の正レンズの物体側面の曲率半径をｒ_２１Ｆ、前記第２群光学系における前記負メニスカスレンズの物体側面の曲率半径をｒ_２２Ｆ、前記第２群光学系における前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率半径をｒ_２２Ｒとし、そして、最大像高をＹ′として、
条件式：
１．４０
＜（（１／ｒ_２１Ｆ ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）
＜２．２０
を満足する。
【０１２４】
請求項３の構成によれば、主として像面湾曲を一層良好に補正した、高性能なズームレンズを提供することができ、その結果、画面周辺でも画質劣化が少なく、一層高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１２５】
本発明の請求項４によるズームレンズは、
請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、
前記第２群光学系の最も物体側の正レンズの物体側面の頂点から該第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の頂点までの距離をＬ_ＰＮ、前記第２群光学系の光軸方向についての厚みをＬ_２として、
条件式：
０．４０＜（Ｌ_ＰＮ／Ｌ_２）＜０．７０
を満足する。
【０１２６】
請求項４の構成によれば、球面収差、非点収差およびコマ収差をさらに良好に補正した、一層高性能なズームレンズを提供することができ、その結果、さらに高い解像力を有する高画質のカメラまたは携帯情報端末装置を実現することができる。
本発明の請求項５によるズームレンズは、
請求項１〜請求項４のうちのいずれか１項のズームレンズにおいて、
前記第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率が、前記第２群光学系の全ての面の中で最も大きい。
【０１２７】
請求項５の構成によれば、単色収差と色収差のバランスが取れた、さらに高性能のズームレンズを提供することができ、その結果、画面周辺部でも色滲みの少ない高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１２８】
本発明の請求項６によるズームレンズは、
請求項１〜請求項５のうちのいずれか１項のズームレンズにおいて、
前記第２群光学系の最も物体側の面と最も像側の面が非球面である。
【０１２９】
請求項６の構成によれば、主として単色収差をさらに良好に補正した、一層高性能のズームレンズを提供することができるため、画面全体にわたって一層高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１３０】
本発明の請求項７によるズームレンズは、
物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、
短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、
前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、
【０１３１】
そして、前記第２群光学系における最も物体側の正レンズの物体側面の曲率半径をｒ_２１Ｆ、前記第２群光学系における前記負メニスカスレンズの物体側面の曲率半径をｒ_２２Ｆ、前記第２群光学系における前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率半径をｒ_２２Ｒとし、そして、最大像高をＹ′として、
条件式：
１．４０
＜（（１／ｒ_２１Ｆ ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）
＜２．２０
を満足する。
【０１３２】
また、本発明の請求項８によるズームレンズは、
物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、
短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、
前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、
そして、前記第２群光学系の最も物体側の正レンズの物体側面の頂点から該第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の頂点までの距離をＬ_ＰＮ、前記第２群光学系の光軸方向についての厚みをＬ_２として、
条件式：
０．４０＜（Ｌ_ＰＮ／Ｌ_２）＜０．７０
を満足する。
【０１３３】
さらに、本発明の請求項９によるズームレンズは、
物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、
短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、
前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、
そして、前記第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率が、前記第２群光学系の全ての面の中で最も大きい。
【０１３４】
請求項７〜請求項９の構成によれば、充分に小型で且つ広画角であって、しかも高性能であり、３００万〜６００万画素の撮像素子に対応した解像力を有するズームレンズを実現することを可能とする他のそれぞれ異なる手段を提供することができ、小型で、広画角で、高画質のカメラまたは携帯情報端末装置を実現することができる。
【０１３５】
本発明の請求項１０によるカメラは、撮影用光学系として、請求項１〜請求項９のいずれか１項に記載のズームレンズを含む。
【０１３６】
請求項１０の構成によれば、十分に小型で且つ広画角であって、しかも高性能であり、３００万〜６００万画素の撮像素子に対応した解像力を有するズームレンズを撮影光学系として使用して、小型で、広画角で、高画質のカメラを提供ことができ、その結果、ユーザは携帯性に優れたカメラで高画質な画像を撮影することが可能となる。
本発明の請求項１１による携帯情報端末装置は、カメラ機能部の撮影用光学系として、請求項１〜請求項９のいずれか１項に記載のズームレンズを含む。
【０１３７】
請求項１１の構成によれば、充分に小型で且つ広画角であって、しかも高性能であり、３００万〜６００万画素の撮像素子に対応した解像力を有するズームレンズをカメラ機能部の撮影光学系として使用して、小型で高画質の携帯情報端末装置を提供ことができ、その結果、ユーザは携帯性に優れた携帯情報端末装置で高画質な画像を撮影し、その画像を外部へ送信するなどすることができる。
【０１３８】
【発明の効果】
以上述べたように、本発明によれば、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系とを少なくとも配置し、且つ前記第２群光学系と一体に移動する絞りを有して、短焦点端から長焦点端への変倍に際して、前記第２群光学系は、像側から物体側へと単調に移動し、前記第１群光学系は、変倍に伴う像面位置の変動を補正するように移動する構成を用いて、充分に小型で且つ広画角を得ることが可能で、しかも高性能であり、充分な解像力を有するズームレンズ、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。
【０１３９】
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、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、そして、前記第２群光学系の前記負メニスカスレンズの屈折率をＮ_２２、前記負メニスカスレンズに接合された前記正メニスカスレンズの屈折率をＮ_２３として、
条件式：
０．１５＜（Ｎ_２２−Ｎ_２３）＜０．４０
を満足することにより、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系とを少なくとも配置し、且つ前記第２群光学系と一体に移動する絞りを有して、短焦点端から長焦点端への変倍に際して、前記第２群光学系は、像側から物体側へと単調に移動し、前記第１群光学系は、変倍に伴う像面位置の変動を補正するように移動する構成を用いて、充分に小型で且つ広画角を得ることができて、しかも高性能で、３００万〜６００万画素の撮像素子に対応する解像力を得ることができる。
【０１４０】
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、前記第２群光学系における前記負メニスカスレンズのアッベ数をν_２２、該負メニスカスレンズに接合された前記正メニスカスレンズのアッベ数をν_２３として、
条件式：
２５＜（ν_２３ −ν_２２ ）＜５０
を満足することにより、特に、色収差をより良好に補正して、さらに高性能とすることができる。
【０１４１】
本発明の請求項３のズームレンズによれば、請求項１または請求項２のズームレンズにおいて、前記第２群光学系における最も物体側の正レンズの物体側面の曲率半径をｒ_２１Ｆ、前記第２群光学系における前記負メニスカスレンズの物体側面の曲率半径をｒ_２２Ｆ、前記第２群光学系における前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率半径をｒ_２２Ｒとし、そして、最大像高をＹ′として、
条件式：
１．４０
＜（（１／ｒ_２１Ｆ ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）
＜２．２０
を満足することにより、特に、主として像面湾曲をさらに良好に補正して、一層高性能とすることができる。
【０１４２】
本発明の請求項４のズームレンズによれば、請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、前記第２群光学系の最も物体側の正レンズの物体側面の頂点から該第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の頂点までの距離をＬ_ＰＮ、前記第２群光学系の光軸方向についての厚みをＬ_２として、
条件式：
０．４０＜（Ｌ_ＰＮ／Ｌ_２）＜０．７０
を満足することにより、特に、球面収差、非点収差およびコマ収差をさらに良好に補正して、一層高性能とすることができる。
【０１４３】
本発明の請求項５のズームレンズによれば、請求項１〜請求項４のうちのいずれか１項のズームレンズにおいて、前記第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率が、前記第２群光学系の全ての面の中で最も大きい構成により、特に、単色収差と色収差とのバランスをとり、一層高性能化することができる。
【０１４４】
本発明の請求項６のズームレンズによれば、請求項１〜請求項５のうちのいずれか１項のズームレンズにおいて、前記第２群光学系の最も物体側の面と最も像側の面が非球面である構成により、特に、主として単色収差をさらに良好に補正して、一層高性能とすることができる。
【０１４５】
本発明の請求項７のズームレンズによれば、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、そして、前記第２群光学系における最も物体側の正レンズの物体側面の曲率半径をｒ_２１Ｆ、前記第２群光学系における前記負メニスカスレンズの物体側面の曲率半径をｒ_２２Ｆ、前記第２群光学系における前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率半径をｒ_２２Ｒとし、そして、最大像高をＹ′として、
条件式：
１．４０
＜（（１／ｒ_２１Ｆ ）＋（１／ｒ_２２Ｆ）＋（１／ｒ_２２Ｒ））×Ｙ′）
＜２．２０
を満足することにより、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系とを少なくとも配置し、且つ前記第２群光学系と一体に移動する絞りを有して、短焦点端から長焦点端への変倍に際して、前記第２群光学系は、像側から物体側へと単調に移動し、前記第１群光学系は、変倍に伴う像面位置の変動を補正するように移動する構成を用いて、充分に小型で且つ広画角を得ることができて、しかも高性能であり、主として像面湾曲を良好に補正して、３００万〜６００万画素の撮像素子に対応する解像力を得ることができる。
【０１４６】
本発明の請求項８のズームレンズによれば、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、そして、前記第２群光学系の最も物体側の正レンズの物体側面の頂点から該第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の頂点までの距離をＬ_ＰＮ、前記第２群光学系の光軸方向についての厚みをＬ_２として、
条件式：
０．４０＜（Ｌ_ＰＮ／Ｌ_２）＜０．７０
を満足することにより、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系とを少なくとも配置し、且つ前記第２群光学系と一体に移動する絞りを有して、短焦点端から長焦点端への変倍に際して、前記第２群光学系は、像側から物体側へと単調に移動し、前記第１群光学系は、変倍に伴う像面位置の変動を補正するように移動する構成を用いて、充分に小型で且つ広画角を得ることができて、しかも高性能であり、球面収差、非点収差およびコマ収差を良好に補正して、３００万〜６００万画素の撮像素子に対応する解像力を得ることができる。
【０１４７】
本発明の請求項９のズームレンズによれば、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系と、正の焦点距離を持つ第３群光学系とを配置し、且つ前記第２群光学系の物体側に該第２群光学系と一体に移動する絞りを有しており、短焦点端から長焦点端への変倍に際して、前記第１群光学系と前記第２群光学系との間隔が漸次小さくなり、前記第２群光学系と前記第３群光学系との間隔が漸次大きくなるように、前記第１群光学系〜前記第３群光学系が移動するズームレンズにおいて、前記第２群光学系が、物体側から順次、物体側に曲率の大きな面を向けた正レンズ、像側に凹面を向けた負メニスカスレンズ、その負メニスカスレンズに接合された正メニスカスレンズ、そして正レンズが配列されてなる３群４枚構成の光学系からなり、そして、前記第２群光学系の前記負メニスカスレンズと前記正メニスカスレンズとの接合面の曲率が、前記第２群光学系の全ての面の中で最も大きい構成により、物体側から、順次、負の焦点距離を持つ第１群光学系と、正の焦点距離を持つ第２群光学系とを少なくとも配置し、且つ前記第２群光学系と一体に移動する絞りを有して、短焦点端から長焦点端への変倍に際して、前記第２群光学系は、像側から物体側へと単調に移動し、前記第１群光学系は、変倍に伴う像面位置の変動を補正するように移動する構成を用いて、充分に小型で且つ広画角を得ることができて、しかも高性能であり、単色収差と色収差とのバランスが良好で、３００万〜６００万画素の撮像素子に対応する解像力を得ることができる。
【０１４８】
そして、本発明の請求項１０のカメラによれば、撮影用光学系として、請求項１〜請求項９のいずれか１項に記載のズームレンズを含むことにより、充分に小型で且つ広画角を得ることが可能で、しかも高性能であり、３００万〜６００万画素の撮像素子に対応する解像力を得るズームレンズを撮影光学系として使用して、小型で且つ高画質を得ることができる。
【０１４９】
また、本発明の請求項１１の携帯情報端末装置によれば、カメラ機能部の撮影用光学系として、請求項１〜請求項９のいずれか１項に記載のズームレンズを含む構成により、充分に小型で且つ広画角を得ることが可能で、しかも高性能であり、３００万〜６００万画素の撮像素子に対応する解像力を得るズームレンズをカメラ機能部の撮影光学系として使用して、小型で且つ高画質を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施例に係るズームレンズの光学系の構成を模式的に示す光軸に沿った断面図を示している。
【図２】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模式的に示す光軸に沿った断面図を示している。
【図３】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模式的に示す光軸に沿った断面図を示している。
【図４】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模式的に示す光軸に沿った断面図を示している。
【図５】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模式的に示す光軸に沿った断面図を示している。
【図６】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模式的に示す光軸に沿った断面図を示している。
【図７】図１に示す本発明の第１の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図８】図１に示す本発明の第１の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図９】図１に示す本発明の第１の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１０】図２に示す本発明の第２の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１１】図２に示す本発明の第２の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１２】図２に示す本発明の第２の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１３】図３に示す本発明の第３の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１４】図３に示す本発明の第３の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１５】図３に示す本発明の第３の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１６】図４に示す本発明の第４の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１７】図４に示す本発明の第４の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１８】図４に示す本発明の第４の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図１９】図５に示す本発明の第５の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２０】図５に示す本発明の第５の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２１】図５に示す本発明の第５の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２２】図６に示す本発明の第６の実施例によるズームレンズの短焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２３】図６に示す本発明の第６の実施例によるズームレンズの中間焦点距離における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２４】図６に示す本発明の第６の実施例によるズームレンズの長焦点端における球面収差、非点収差、歪曲収差およびコマ収差を示す収差曲線図である。
【図２５】本発明の第７の実施例に係るカメラの外観構成を模式的に示す物体側から見た斜視図であり、（ａ）は撮影レンズがカメラのボディー内に沈胴埋没している状態、（ｂ）は撮影レンズがカメラのボディーから突出している状態を示している。
【図２６】図２５のカメラの外観構成を模式的に示す撮影者側から見た斜視図である。
【図２７】図２５のカメラの機能構成を模式的に示すブロック図である。
【符号の説明】
Ｇ１ 第１群光学系
Ｇ２ 第２群光学系
Ｇ３ 第３群光学系
Ｅ１〜Ｅ９ レンズ
ＦＡ 絞り
ＯＦ 各種光学フィルタ
１０１ 撮影レンズ
１０２ シャッタボタン
１０３ ズームレバー
１０４ ファインダ
１０５ ストロボ
１０６ 液晶モニタ
１０７ 操作ボタン
１０８ 電源スイッチ
１０９ メモリカードスロット
１１０ 通信カードスロット
２０１ 受光素子（エリアセンサ）
２０２ 信号処理装置
２０３ 画像処理装置
２０４ 中央演算装置（ＣＰＵ）
２０５ 半導体メモリ
２０６ 通信カード等[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a zoom lens used as an optical system for photographing various cameras including a so-called silver halide camera, and in particular, a zoom lens suitable for cameras such as digital cameras and video cameras, and such a zoom lens And a portable information terminal device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a conventional camera using a silver halide film, that is, a digital camera or an electronic camera instead of a silver halide camera, is used to capture a subject image by a solid-state imaging device such as a CCD (charge coupled device) imaging device. A camera of the type that obtains image data of a still image (still image) or a moving image (movie image) of a subject and digitally records the data in a nonvolatile semiconductor memory represented by a flash memory is rapidly becoming widespread. is there.
The market for such digital cameras has become extremely large, and users' demands for digital cameras have been diversified. In particular, high image quality and miniaturization are always desired by the user in the camera and occupy a large weight. Therefore, a zoom lens used as a photographing lens is also required to have both high performance and small size.
[0003]
Here, in terms of miniaturization, first, it is necessary to shorten the entire length of the lens (the distance from the lens surface closest to the object side to the image plane). Further, from the aspect of high performance, it is necessary to have a resolution corresponding to an image sensor having at least 3 to 6 million pixels over the entire zoom range.
In addition, many users desire a wider angle of view of the photographing lens, and it is preferable that the half angle of view at the short focal length end of the zoom lens is 38 degrees or more. The half angle of view of 38 degrees corresponds to a focal length of 28 mm converted into a camera using a 35 mm silver halide film (a so-called Leica plate).
[0004]
There are many types of zoom lenses that can be used as a photographing lens of a digital camera. As a zoom lens of a type suitable for miniaturization, a first group optical system having a negative focal length in order from the object side and a positive lens And a third group optical system having a positive focal length are arranged and provided integrally with the second group optical system on the object side of the second group optical system. A second stop optical system that monotonously moves from the image side to the object side during zooming from the short focus end to the long focus end, and the first group optical system Some are moved so as to correct the change of the image plane position due to the magnification change. Such a type of zoom lens is disclosed in, for example, Patent Document 1, Patent Document 2, Patent Document 3, and the like.
[0005]
[Patent Document 1]
JP-A-10-39214
[Patent Document 2]
JP-A-10-104518
[Patent Document 3]
JP 2001-296476 A
[0006]
[Problems to be solved by the invention]
However, the one disclosed in Patent Document 1 was filed as the earliest application as a zoom lens of the type described above, and all of the basic configurations of the zoom lens of the type described above are disclosed. However, it does not have a sufficient structure in terms of realization. Further, the configuration disclosed in Patent Document 2 takes into consideration the occurrence of eccentricity during assembly using a cemented lens, but the aberration correction is not sufficiently performed, and 3 to 6 million pixels are not provided. It does not have the performance that can correspond to the image sensor of the above. The one disclosed in Patent Literature 3 is relatively small and has better image performance than that described above, but the half angle of view is limited to about 33 degrees, which means that the angle of view is increased. In terms of terms, it is not enough.
[0007]
The present invention has been made in view of the above circumstances, and sequentially arranges at least a first group optical system having a negative focal length and a second group optical system having a positive focal length from the object side. And a stop that moves integrally with the second group optical system, and the second group optical system monotonously moves from the image side to the object side during zooming from the short focal end to the long focal end. However, the first lens group optical system is configured to move so as to correct a change in the image plane position caused by zooming, and it is possible to obtain a sufficiently small size, a wide angle of view, and high performance. It is an object of the present invention to provide a zoom lens, a camera, and a portable information terminal device having a sufficient resolution.
That is, an object of claim 1 of the present invention is to obtain a resolving power corresponding to an image sensor having 3 to 6 million pixels, which is sufficiently small, can obtain a wide angle of view, and has high performance. It is to provide a zoom lens that enables the above.
It is another object of the present invention to provide a zoom lens capable of correcting chromatic aberration more favorably and achieving higher performance.
[0008]
An object of a third aspect of the present invention is to provide a zoom lens capable of correcting the curvature of field more favorably and achieving higher performance.
It is an object of a fourth aspect of the present invention to provide a zoom lens capable of further correcting spherical aberration, astigmatism, and coma aberration to achieve higher performance.
An object of claim 5 of the present invention is to provide a zoom lens which can balance monochromatic aberration and chromatic aberration to further improve the performance.
An object of claim 6 of the present invention is to provide a zoom lens which can mainly correct monochromatic aberration more satisfactorily and achieve higher performance.
It is an object of claim 7 of the present invention to achieve, in particular, a sufficiently small size and a wide angle of view, high performance, and good correction of field curvature, and 3 to 6 million pixels. It is an object of the present invention to provide a zoom lens capable of obtaining a resolving power corresponding to the image pickup device described above.
[0009]
The object of claim 8 of the present invention is to achieve a particularly small size, a wide angle of view, high performance, good correction of spherical aberration, astigmatism, and coma. An object of the present invention is to provide a zoom lens capable of obtaining a resolving power corresponding to an image sensor having 10,000 to 6 million pixels.
The object of claim 9 of the present invention is to achieve a sufficiently small size and a wide angle of view, high performance, a good balance between monochromatic aberration and chromatic aberration, and 3 to 6 million pixels. It is an object of the present invention to provide a zoom lens capable of obtaining a resolving power corresponding to the image pickup device described above.
An object of claim 10 of the present invention is to obtain a resolution that is sufficiently small, can obtain a wide angle of view, is high-performance, and corresponds to an image sensor having 3 to 6 million pixels. It is an object of the present invention to provide a camera that is small and can obtain high image quality by using a zoom lens as a photographing optical system.
An object of claim 11 of the present invention is to obtain a resolving power corresponding to an image pickup device having 3 to 6 million pixels, which is sufficiently small in size, can obtain a wide angle of view, and has high performance. It is an object of the present invention to provide a portable information terminal device that can obtain a small size and high image quality by using a zoom lens as a photographing optical system of a camera function unit.
[0010]
[Means for Solving the Problems]
The zoom lens according to the first aspect of the present invention has the following features.
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
Then, the refractive index of the negative meniscus lens of the second group optical system is set to N₂₂, The refractive index of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
0.15 <(N₂₂-N₂₃) <0.40
It is characterized by satisfying.
[0011]
A zoom lens according to a second aspect of the present invention is the zoom lens according to the first aspect,
The Abbe number of the negative meniscus lens in the second group optical system is ν₂₂, The Abbe number of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
25 <(ν₂₃  −ν₂₂  ) <50
It is characterized by satisfying.
[0012]
A zoom lens according to a third aspect of the present invention is the zoom lens according to the first or second aspect,
The radius of curvature of the object side surface of the most object side positive lens in the second group optical system is r_21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′,
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
It is characterized by satisfying.
[0013]
A zoom lens according to a fourth aspect of the present invention is the zoom lens according to any one of the first to third aspects,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
It is characterized by satisfying.
[0014]
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to any one of the first to fourth aspects,
The curvature of the joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all the surfaces of the second group optical system.
The zoom lens according to the present invention described in claim 6 is the zoom lens according to any one of claims 1 to 5,
The most object side surface and the most image side surface of the second group optical system are aspherical surfaces.
[0015]
According to a seventh aspect of the present invention, there is provided a zoom lens for achieving the above object.
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and Consists of an optical system of three groups and four elements in which positive lenses are arranged,
Then, the radius of curvature of the object side surface of the positive lens closest to the object in the second group optical system is represented by r._21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
It is characterized by satisfying.
[0016]
The zoom lens according to the present invention described in claim 8 achieves the object described above,
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focus end to the long focus end, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and Consists of an optical system of three groups and four elements in which positive lenses are arranged,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
It is characterized by satisfying.
[0017]
The zoom lens according to the present invention described in claim 9 achieves the above object by
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and Consists of an optical system of three groups and four elements in which positive lenses are arranged,
Further, a curvature of a joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all the surfaces of the second group optical system.
[0018]
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 in order to achieve the above object. And
In order to achieve the above object, the portable information terminal device according to the present invention as described in claim 11, as a photographing optical system of a camera function unit, according to any one of claims 1 to 9, It is characterized by including a zoom lens.
[0019]
[Action]
That is, the zoom lens according to the first aspect of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
Then, the refractive index of the negative meniscus lens of the second group optical system is set to N₂₂, The refractive index of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
0.15 <(N₂₂-N₂₃) <0.40
To be satisfied.
[0020]
With this configuration, at least the first group optical system having a negative focal length and the second group optical system having a positive focal length are arranged at least from the object side, and The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to compensate for a change in the image plane position due to zooming, it is possible to obtain a sufficiently small size and a wide angle of view, and at the same time, perform high-performance imaging of 3 to 6 million pixels. It is also possible to obtain a resolving power corresponding to the element.
[0021]
The zoom lens according to claim 2 of the present invention is the zoom lens according to claim 1,
The Abbe number of the negative meniscus lens in the second group optical system is ν₂₂, The Abbe number of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
25 <(ν₂₃  −ν₂₂  ) <50
To be satisfied.
[0022]
With such a configuration, in particular, chromatic aberration can be corrected more favorably, and higher performance can be achieved.
A zoom lens according to a third aspect of the present invention is the zoom lens according to the first or second aspect,
The radius of curvature of the object side surface of the most object side positive lens in the second group optical system is r_21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
To be satisfied.
[0023]
With such a configuration, in particular, it is possible to further mainly correct the field curvature more satisfactorily to achieve higher performance.
A zoom lens according to claim 4 of the present invention is the zoom lens according to any one of claims 1 to 3,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
To be satisfied.
With such a configuration, in particular, spherical aberration, astigmatism, and coma aberration can be more favorably corrected to achieve higher performance.
[0024]
A zoom lens according to a fifth aspect of the present invention, in the zoom lens according to any one of the first to fourth aspects, is a joining surface between the negative meniscus lens and the positive meniscus lens of the second group optical system. Is the largest of all the surfaces of the second group optical system.
With such a configuration, in particular, it is possible to balance monochromatic aberration and chromatic aberration, and to further improve performance.
A zoom lens according to a sixth aspect of the present invention is the zoom lens according to any one of the first to fifth aspects, wherein the most object-side surface and the most image-side surface of the second group optical system are non-contact. It is a spherical surface.
With such a configuration, in particular, it is possible to further mainly correct monochromatic aberration, and to achieve higher performance.
[0025]
The zoom lens according to claim 7 of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
Then, the radius of curvature of the object side surface of the positive lens closest to the object in the second group optical system is represented by r._21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
To be satisfied.
[0026]
With this configuration, at least the first group optical system having a negative focal length and the second group optical system having a positive focal length are arranged at least from the object side, and The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. It is possible to obtain a sufficiently small size and a wide angle of view by using a structure that moves so as to compensate for a change in the image plane position caused by zooming. By performing the correction, it is possible to obtain a resolution corresponding to an image sensor having 3 to 6 million pixels.
[0027]
The zoom lens according to claim 8 of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
To be satisfied.
[0028]
With this configuration, at least the first group optical system having a negative focal length and the second group optical system having a positive focal length are arranged at least from the object side, and The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to correct the variation of the image plane position due to zooming, it is possible to obtain a sufficiently small size and a wide angle of view, and at the same time, it has high performance, and has a spherical aberration, an astigmatism and It is possible to satisfactorily correct coma and obtain a resolution corresponding to an image sensor having 3 to 6 million pixels.
[0029]
The zoom lens according to the ninth aspect of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The curvature of the joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all the surfaces of the second group optical system.
[0030]
According to such a configuration, at least the first group optical system having a negative focal length and the second group optical system having a positive focal length are arranged at least from the object side, and The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to correct the fluctuation of the image plane position due to zooming, it is possible to obtain a sufficiently small size and wide angle of view, and it is also high performance, and the balance between monochromatic aberration and chromatic aberration. And a resolution corresponding to an image sensor having 3 to 6 million pixels can be obtained.
[0031]
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, a zoom lens that is sufficiently small, can obtain a wide angle of view, has high performance, and obtains a resolution corresponding to an image sensor having 3 to 6 million pixels is used as an imaging optical system. Thus, it is possible to obtain a small size and high image quality.
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, a zoom lens capable of obtaining a sufficiently small size and a wide angle of view, high performance, and obtaining a resolution corresponding to an image sensor having 3 to 6 million pixels can be obtained by photographing the camera function unit. By using it as an optical system, it is possible to obtain a small and high image quality.
[0032]
【Example】
Hereinafter, a zoom lens, a camera, and a portable information terminal device of the present invention will be described in detail based on embodiments with reference to the drawings. Before describing a specific embodiment, first, in order to explain a basic configuration of the present invention, a configuration and a function thereof defined in each claim of the claims will be described.
The zoom lens according to the first to ninth aspects of the present invention sequentially includes, from the object side, a first group optical system having a negative focal length, a second group optical system having a positive focal length, and a positive lens. A third group optical system having a focal length is arranged, and a stop is provided on the object side of the second group optical system so as to move integrally with the second group optical system. During zooming, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system gradually increases. An optical system is a zoom lens that moves, and the zoom lenses according to claims 1 to 9 further have the following features, respectively.
[0033]
2. The zoom lens according to claim 1, wherein the second group optical system sequentially includes, from the object side, a positive lens having a surface having a large curvature toward the object side, a negative meniscus lens having a concave surface facing the image side, and the negative meniscus. It is composed of a positive meniscus lens cemented to a lens, and a three-group four-element configuration in which a positive lens is arranged. The refractive index of the negative meniscus lens of the second group optical system is set to N₂₂, The refractive index of the positive meniscus lens joined to the negative meniscus lens to N₂₃Then, the following conditional expression is satisfied.
0.15 <(N₂₂-N₂₃) <0.40
The zoom lens according to claim 2 is the zoom lens according to claim 1, wherein the Abbe number of the negative meniscus lens of the second group optical system is ν.₂₂, The Abbe number of the positive meniscus lens joined to the negative meniscus lens₂₃Then, the following conditional expression is satisfied.
[0034]
25 <(ν₂₃−ν₂₂) <50
A zoom lens according to a third aspect is the zoom lens according to the first or second aspect, wherein the radius of curvature of the object side surface of the most object-side positive lens of the second group optical system is r._{21 F}The radius of curvature of the object side surface of the negative meniscus lens of the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is r_22RWhen the maximum image height is Y ′, the following conditional expression is satisfied.
[0035]
1.40
<((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
A zoom lens according to a fourth aspect is the zoom lens according to any one of the first to third aspects, wherein the second group optical system is arranged such that a vertex of an object side surface of a positive lens closest to the object in the second group optical system. The distance from the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the system is L_PN, The thickness of the second group optical system in the optical axis direction is L₂Then, the following conditional expression is satisfied.
[0036]
0.40 <(L_PN/ L₂) <0.70
The zoom lens according to claim 5, wherein in the zoom lens according to any one of claims 1 to 4, a curvature of a joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is: This is the largest curvature of all the surfaces of the second group optical system.
A zoom lens according to a sixth aspect is the zoom lens according to any one of the third to fifth aspects, wherein the most object side surface and the most image side surface of the second group optical system are aspherical. .
[0037]
8. The zoom lens according to claim 7, wherein the second group optical system sequentially includes, from the object side, a positive lens having a surface having a large curvature toward the object side, a negative meniscus lens having a concave surface facing the image side, and the negative meniscus. It has a positive meniscus lens cemented to a lens, and a three-group, four-element configuration in which a positive lens is arranged. The radius of curvature of the object side surface of the most object-side positive lens of the second group optical system is r._21FThe radius of curvature of the object side surface of the negative meniscus lens of the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is r_22RWhen the maximum image height is Y ′, the following conditional expression is satisfied.
[0038]
1.40
<((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
9. The zoom lens according to claim 8, wherein the second group optical system sequentially includes, from the object side, a positive lens having a surface having a large curvature toward the object side, a negative meniscus lens having a concave surface facing the image side, and the negative meniscus thereof. The second group optical system comprises a positive meniscus lens cemented to a lens, and a three-group four-element configuration in which a positive lens is disposed. Let L be the distance to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens._PN, The thickness of the second group optical system in the optical axis direction is L₂Then, the following conditional expression is satisfied.
[0039]
0.40 <(L_PN/ L₂) <0.70
10. The zoom lens according to claim 9, wherein the second group optical system includes, in order from the object side, a positive lens having a surface having a large curvature toward the object side, a negative meniscus lens having a concave surface facing the image side, and the negative meniscus thereof. It has a three-element, four-element configuration in which a positive meniscus lens joined to a lens and a positive lens are arranged, and the curvature of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the second lens group. This is the largest curvature among all surfaces of the group optical system.
[0040]
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.
A portable information terminal device according to claim 11 of the present invention includes the zoom lens according to any one of claims 1 to 9 as a photographing optical system of a camera function unit.
[0041]
In general, a zoom lens composed of three groups of negative, positive and positive, such as the zoom lens according to the present invention, has a second group optical system that moves from the image side when zooming from the short focus end to the long focus end. It moves monotonously to the object side, and the first group optical system moves so as to correct the change in the image plane position due to the magnification change. Most of the zooming function is performed by the second group optical system, and the third group optical system is provided mainly to keep the exit pupil away from the image plane.
In order to realize a zoom lens having a high resolution with a small amount of various aberrations, aberration fluctuations due to zooming must be kept small. In particular, the second-group optical system, which is the main zooming group, is good over the entire zooming range. It is necessary that the aberration be corrected. For this reason, it is conceivable to increase the number of components of the second group optical system. However, an increase in the number of components leads to an increase in the thickness of the second group optical system in the optical axis direction, and sufficient miniaturization can be achieved. Not only will it disappear, but it will also increase costs.
As a second group optical system composed of four or less lenses, a positive lens, a negative lens, and a positive lens are arranged in order from the object side, and a positive lens and a positive lens are arranged in order from the object side. And three lenses of a negative lens, in order from the object side, four lenses of a positive lens, a positive lens, a negative lens and a positive lens, and a positive lens and a negative lens in order from the object side , A negative lens and a positive lens are arranged, and the present invention realizes a configuration of a second group optical system having an aberration correcting ability exceeding these.
[0042]
That is, in the present invention, the second group optical system is composed of four lenses arranged in this order from the object side: a positive lens, a negative lens, a positive lens, and a positive lens. Since the aperture stop is arranged on the object side of the second group optical system, since the off-axis ray passes through a place farther from the optical axis as the lens surface on the image side is farther from the aperture stop in the second group optical system, The involvement in correction of external aberrations is deepened. The second group optical system has a symmetrical arrangement having positive power on both sides of negative power as a whole. However, the positive power on the image side, which is deeply involved in correction of off-axis aberration, is provided by two sheets. Dividing into lenses increases the degree of freedom and enables good correction of off-axis aberrations.
[0043]
Further, in the present invention, the second group optical system is sequentially joined from the object side to a positive lens having a surface having a large curvature toward the object side, a negative meniscus lens having a concave surface facing the image side, and the negative meniscus lens. And a positive meniscus lens, and a lens group of three and four lenses each including the positive lens. Joining the second negative lens and the third positive lens from the object side is effective in suppressing assembly eccentricity and reducing assembly man-hours. Further, the second negative lens from the object side is made into a meniscus shape to have a positive power on the object side surface, thereby sharing the positive power with the most positive lens on the object side, and the third positive lens from the object side. By making the lens a meniscus shape and giving negative power to the image side surface, the joint surface and the negative power are shared, preventing the occurrence of excessive aberration on a specific surface, and the entire second group optical system And a reduction in the manufacturing error sensitivity.
[0044]
In addition, when the configuration satisfies the following conditional expression, sufficient aberration correction is possible (corresponding to claim 1).
[0045]
0.15 <(N₂₂-N₂₃) <0.40
Where N₂₂Is the refractive index of the negative meniscus lens of the second group optical system, N₂₃Represents the refractive index of the positive meniscus lens joined to the negative meniscus lens.
In this case, (N₂₂-N₂₃) Is 0.15 or less, it becomes difficult to give a sufficient negative power to the joint surface, and it becomes impossible to correct the curvature of field. On the other hand, (N₂₂-N₂₃When the value of ()) is 0.4 or more, a very high refractive index is required for the negative meniscus lens, which causes an increase in manufacturing cost. It is more preferable that the zoom lens be configured so as to satisfy the following conditional expression.
[0046]
0.20 <(N₂₂-N₂₃) <0.40
In order to perform chromatic aberration correction more sufficiently, it is desirable that the configuration satisfy the following conditional expression (corresponding to claim 2).
[0047]
25 <(ν₂₃−ν₂₂) <50
Where ν₂₂Is the Abbe number of the negative meniscus lens of the second group optical system, ν₂₃Represents the Abbe number of the positive meniscus lens joined to the negative meniscus lens.
In this case, (ν₂₃−ν₂₂) Is not more than 25, it is difficult to sufficiently control the chromatic aberration at the joint surface, and it is difficult to achieve both the correction of the axial chromatic aberration and the correction of the chromatic aberration of magnification. On the other hand, (ν₂₃−ν₂₂When the value of ()) is 50 or more, a very small dispersion is required for the positive meniscus lens, and the production cost is increased. It is more preferable that the zoom lens be configured so as to satisfy the following conditional expression.
[0048]
30 <(ν₂₃−ν₂₂) <50
Furthermore, in order to improve the curvature of field, it is desirable to adopt a configuration satisfying the following conditional expression (corresponding to claim 3).
1.40
<((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
Where r_21FIs the radius of curvature of the object side surface of the positive lens closest to the object side of the second group optical system, r_22FIs the radius of curvature of the object side surface of the negative meniscus lens of the second group optical system, r_22RIs the radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system, and Y 'represents the maximum image height.
[0049]
In this case, ((1 / r_21F  ) + (1 / r_22F) + (1 / r_22RIf the value of ()) × Y ′) is increased beyond 1.40, the curvature of field of the second group optical system can be sufficiently corrected, and the flatness of the image surface can be maintained over the entire zoom range. Become. However, ((1 / r_21F) + (1 / r_22F) + (1 / r_22RIf the value of ()) × Y ′) is increased to 2.20 or more, the aberration occurring on each surface of the second group optical system increases, the exchange of aberrations increases, and the manufacturing error sensitivity increases. It is more preferable that the zoom lens be configured so as to satisfy the following conditional expression.
[0050]
1.55
<((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.05
Furthermore, in order to improve spherical aberration, astigmatism, and coma, it is desirable to adopt a configuration satisfying the following conditional expression (corresponding to claim 4).
[0051]
0.40 <(L_PN/ L₂) <0.70
Where L_PNIs the distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system, L₂Represents the thickness of the second group optical system in the optical axis direction.
[0052]
In the second group optical system, the object side surface of the positive lens closest to the object side and the cemented surface of the negative meniscus lens and the positive meniscus lens both have small curvatures, and exchange large aberrations with each other to contribute most to aberration correction. are doing. In order to perform good aberration correction, the height of a light ray passing through these two surfaces is important. (L_PN/ L₂) Is 0.40 or less, the height of the off-axis principal ray on the image side surface of the second negative lens from the object side becomes too small, and correction of astigmatism and coma may be insufficient. On the other hand, (L_PN/ L₂) Is 0.70 or more, the axial marginal ray height on the image side surface of the second negative lens from the object side becomes too small, and correction of spherical aberration may be insufficient. It is more preferable that the zoom lens be configured so as to satisfy the following conditional expression.
[0053]
0.45 <(L_PN/ L₂) <0.65
In order to achieve a better balance between monochromatic aberration and chromatic aberration, the curvature of the cemented surface between the negative meniscus lens and the positive meniscus lens of the second group optical system must be set within all the surfaces of the second group optical system. It is desirable to have the largest configuration (corresponding to claim 5). In the second group optical system, if the curvature of the surface other than the cemented surface is larger than the curvature of the cemented surface, it becomes difficult to balance axial chromatic aberration and lateral chromatic aberration while satisfactorily correcting monochromatic aberration.
[0054]
For better correction of monochromatic aberration, it is preferable that the second group optical system has two or more aspheric surfaces. By using two aspherical surfaces at locations where the directions of light rays are different from each other, it is possible to improve the degree of freedom of aberration correction. In order to perform the most effective aberration correction, it is desirable that the most object side surface and the most image side surface of the second group optical system are aspherical surfaces (corresponding to claim 6). Since the most object-side surface of the second group optical system is near the stop, the on-axis and off-axis light beams pass through with little separation, and the aspheric surface provided here is mainly used for correcting spherical aberration and coma. Contribute. On the other hand, since the most image side surface of the second group optical system is far from the stop, the on-axis and off-axis light beams pass through with some separation, and the aspheric surface provided here contributes to correction of astigmatism and the like. I do. By using two aspheric surfaces for the most object-side surface and the most image-side surface in this way, the respective aspheric surfaces have sufficiently different effects, and the degree of freedom of aberration correction is dramatically increased. It will increase.
[0055]
Note that the present invention may achieve the intended purpose as any one of the following three configurations.
That is, a first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side. A stop is provided on the object side of the second group optical system to move integrally with the second group optical system. When the magnification is changed from the short focal end to the long focal end, the first group optical system and the second In a zoom lens in which each group moves such that the distance between the group optical systems becomes smaller and the distance between the second group optical system and the third group optical system becomes larger, the second group optical system is arranged from the object side. It consists of a positive lens with a surface with a large curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and a three-element four-element configuration in which a positive lens is sequentially arranged. , Satisfying the following conditional expression (corresponding to claim 7).
[0056]
1.40
<((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
Alternatively, a first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side, A stop is provided on the object side of the second group optical system to move integrally with the second group optical system. When the magnification is changed from the short focal end to the long focal end, the first group optical system and the second In a zoom lens in which each group moves such that the distance between the group optical systems becomes smaller and the distance between the second group optical system and the third group optical system becomes larger, the second group optical system is arranged from the object side. It consists of a positive lens with a surface with a large curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and a three-element four-element configuration in which a positive lens is sequentially arranged. , Satisfying the following conditional expression (corresponding to claim 8).
[0057]
0.40 <(L_PN/ L₂) <0.70
Alternatively, a first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side, A stop is provided on the object side of the second group optical system to move integrally with the second group optical system. When the magnification is changed from the short focal end to the long focal end, the first group optical system and the second In a zoom lens in which each group moves such that the distance between the group optical systems becomes smaller and the distance between the second group optical system and the third group optical system becomes larger, the second group optical system is arranged from the object side. It consists of a positive lens with a surface with a large curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and a three-element four-element configuration in which a positive lens is sequentially arranged. A negative meniscus lens and a positive meniscus lens of the second group optical system Curvature of the cemented surfaces of, and becomes largest structure in all aspects of the second group optical system (corresponding to claim 9).
By adopting each of these configurations, it is possible to independently obtain the above-described effects on aberration correction.
[0058]
The feature of the present invention lies in the configuration of the second group optical system as described above. Conditions for better aberration correction as a zoom lens will be described below.
The first group optical system includes, in order from the object side, at least one negative lens having a surface with a large curvature directed to the image side and at least one positive lens having a surface having a large curvature directed to the object side. Preferably, the image side surface of the negative lens is aspheric. With the first group optical system having such a configuration, the curvature of field can be reduced, and the surface having a large off-axis ray refraction angle can be made aspherical, so that distortion at the short focal length end can be achieved. Aberration can be suppressed.
[0059]
More specifically, the first group optical system includes, from the object side to the image side, a negative meniscus lens having a convex surface facing the object side, and a negative lens having a surface having a large curvature facing the image side. A configuration in which three lenses of a positive lens with a surface having a large curvature facing the object side are arranged, and the image-side surface of the negative lens is an aspheric surface can be adopted. According to such a configuration, the aberration correction ability is further enhanced, which is advantageous for widening the angle of view.
[0060]
The third group optical system is composed of a positive lens having a surface with a large curvature directed to the object side, and desirably has at least one aspheric surface. According to such a configuration, off-axis aberrations such as astigmatism can be more favorably corrected while minimizing the thickness of the third group optical system. Further, the third group optical system may be fixed at the time of zooming, but by moving a small amount, the degree of freedom of aberration correction can be increased.
[0061]
Next, specific examples of the zoom lens, the camera, and the portable information terminal device according to the present invention that reflect the above-described configuration will be described in detail. The first, second, third, fourth, fifth, and sixth embodiments are embodiments of the zoom lens according to the present invention, and the seventh embodiment is different from the first to sixth embodiments. It is an example of a camera or a portable information terminal device according to the present invention using a zoom lens as shown as a photographing optical system.
In the first to sixth embodiments showing the zoom lens according to the present invention, the configuration of the zoom lens and specific numerical examples are shown. The maximum image height in all of the first to sixth embodiments is 4.65 mm. In each of the first to sixth embodiments, the aberration has been sufficiently corrected, and it is possible to correspond to a light receiving element having 3 to 6 million pixels. It will be apparent from these first to sixth embodiments that by configuring the zoom lens as in the present invention, it is possible to secure a very good image performance while achieving a sufficient miniaturization. .
[0062]
In the following description relating to the first to sixth embodiments, the following various symbols are used.
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: Conical constant of aspherical surface
A₄: 4th order aspherical coefficient
A₆: 6th order aspheric coefficient
A₈: 8th order aspherical coefficient
A₁₀: 10th order aspherical coefficient
A₁₂: 12th order aspheric coefficient
A₁₄: 14th order aspherical coefficient
A₁₆: 16th order aspherical coefficient
A₁₈: 18th order aspherical 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.
[0063]
(Equation 1)

[0064]
[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 diaphragm FA. And an optical filter OF. In this case, the first lens E1 to the third lens E3 constitute a first group optical system G1, the fourth lens E4 to the seventh lens E7 constitute a second group optical system G2, and the eighth lens E8 , And a third group optical system G3, which is supported by a common support frame or the like appropriate for each group, and operates integrally for each group during zooming or the like. FIG. 1 schematically shows the movement locus of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end from the short focal length end at the wide angle end so that the zooming operation can be grasped. Indicated by arrows. FIG. 1 also shows the surface number of each optical surface. 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. This is not the same configuration as the embodiment.
[0065]
In FIG. 1, a first lens E1, a second lens E2, a third lens E3, an aperture FA, a fourth lens E4, a fifth lens E5, a sixth lens E6, and a seventh lens, for example, sequentially from the object side such as a subject. E7, the eighth lens E8, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0066]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a negative meniscus lens formed convex on the object side, and the third lens E3 is a positive meniscus lens formed on the object side. The first group optical system G1, which is a lens (a plano-convex lens) and includes the first lens E1 to the third lens E3, exhibits a negative focal length as a whole. The fourth lens E4 is a positive meniscus lens formed convex on the object side, the fifth lens E5 is a negative meniscus lens formed convex on the object side, and the sixth lens E6 is formed convex on the object side. The positive meniscus lens and the seventh lens E7 are positive lenses (biconvex lenses), and the fifth lens E5 and the sixth lens E6 are cemented. The second group optical system G2 constituted by E7 has a positive focal length as a whole. The eighth lens E8 is a positive meniscus lens that is formed convex on the object side, and only the eighth lens E8 constitutes a third group optical system G3 having a positive focal length. The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0067]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0068]
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 = 5.93 to 16.78 and F = 2.57 to 4.37, respectively, by zooming. , And ω = 39.42 to 15.62. The characteristics of each optical surface are as shown in the following table.
[0069]
[Table 1]
optical properties

[0070]
In Table 1, each of the fourth, eighth, fourteenth, and fifteenth optical surfaces with an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 4th surface
K = 0.0, A₄= -2.78493 × 10^-4, A₆= −4.55722 × 10^-6, A₈= 2.85397 × 10^-7, A₁₀= -1.90695 × 10^-8, A₁₂= 5.07288 × 10^-10, A₁₄= -1.90194 × 10^-12, A₁₆= -1.68241 x 10^-13, A₁₈= 2.3370 × 10^-15
Aspheric surface: 8th surface
K = 0.0, A₄= −8.554569 × 10^-5, A₆= -3.60180 × 10^-7, A₈= -3.63648 × 10^-8, A₁₀= 9.613335 × 10^-10
Aspheric surface: 14th surface
K = 0.0, A₄= 1.67112 × 10^-4, A₆= 6.29478 × 10^-6, A₈= −3.96383 × 10^-7, A₁₀= 2.14222 × 10^-8Aspheric surface: 15th surface
K = 0.0, A₄= −1.51122 × 10^-5, A₆= 2.94709 × 10^-6, A₈= −1.16281 × 10^-7, A₁₀= 2.05071 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0071]
[Table 2]
Variable interval

[0072]
The numerical values of the above-described conditional expressions of the present invention in the first embodiment are as follows, and are within the range of the conditional expressions.
Conditional expression
(N₂₂-N₂₃) = 0.359
(Ν₂₃  −ν₂₂  ) = 46.7
((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.79
(L_PN/ L₂) = 0.589
[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 diaphragm FA. And an optical filter OF. In this case, the first lens E1 to the third lens E3 constitute a first group optical system G1, the fourth lens E4 to the seventh lens E7 constitute a second group optical system G2, and the eighth lens E8 , And a third group optical system G3, which is supported by a common support frame or the like appropriate for each group, and operates integrally for each group during zooming or the like. FIG. 2 also shows a schematic movement trajectory of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end from the short focal length end at the wide angle end so that the zooming operation can be grasped. This is schematically indicated by an arrow. FIG. 2 also shows the surface number of each optical surface. As mentioned above, each reference numeral for FIG. 2 is also used independently of the other embodiments.
[0073]
In FIG. 2, for example, the first lens E1, the second lens E2, the third lens E3, the aperture FA, the fourth lens E4, the fifth lens E5, the sixth lens E6, and the seventh lens E1 are sequentially arranged from the object side such as a subject. The lens E7, the eighth lens E8, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0074]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a negative meniscus lens formed convex on the object side, and the third lens E3 is a convex surface having a large curvature on the object side. The first group optical system G1 including the first lens E1 to the third lens E3 has a negative focal length as a whole. The fourth lens E4 is a positive meniscus lens formed convex on the object side, the fifth lens E5 is a negative meniscus lens formed convex on the object side, and the sixth lens E6 is formed convex on the object side. The positive meniscus lens and the seventh lens E7 are positive lenses (biconvex lenses), and the fifth lens E5 and the sixth lens E6 are cemented. The second group optical system G2 constituted by E7 has a positive focal length as a whole. The eighth lens E8 is a positive meniscus lens that is formed convex on the object side, and only the eighth lens E8 constitutes a third group optical system G3 having a positive focal length. The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0075]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0076]
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 = 5.97 to 16.86 and F = 2.58 to 4.34, respectively, by zooming. , And ω = 39.21-15.54. The characteristics of each optical surface are as shown in the following table.
[0077]
[Table 3]
optical properties

[0078]
In Table 3, each of the fourth, eighth, fourteenth, and fifteenth optical surfaces having an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 4th surface
K = 0.0, A₄= −3.665774 × 10^-4, A₆= −6.998063 × 10^-6, A₈= 3.3239 × 10^-7, A₁₀= −2.1223 × 10^-8, A₁₂= 4.75955 × 10^-10, A₁₄= −1.53407 × 10^-12, A₁₆= -1.2519 × 10^-13, A₁₈= 1.38231 x 10^-15
Aspheric surface: 8th surface
K = 0.0, A₄= −8.22942 × 10^-5, A₆= −3.49540 × 10^-7, A₈= -4.22060 × 10^-8, A₁₀= 1.43521 × 10^-9
Aspheric surface: 14th surface
K = 0.0, A₄= 8.6362 × 10^-5, A₆= 1.08403 × 10^-5, A₈= -1.14432 × 10^-6, A₁₀= 5.555500 × 10^-8Aspheric surface: 15th surface
K = 0.0, A₄= -1.42708 x 10^-5, A₆= 3.15235 × 10^-6, A₈= -1.333726 * 10^-7, A₁₀= 2.51387 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0079]
[Table 4]
Variable interval

[0080]
The numerical values of the above-described conditional expressions of the present invention in the second embodiment are as follows and are within the range of the conditional expressions.
Conditional expression
(N₂₂-N₂₃) = 0.330
(Ν₂₃−ν₂₂) = 40.4
((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.73
(L_PN/ L₂) = 0.594
[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 diaphragm FA. And an optical filter OF. In this case, the first lens E1 to the third lens E3 constitute a first group optical system G1, the fourth lens E4 to the seventh lens E7 constitute a second group optical system G2, and the eighth lens E8 , And a third group optical system G3, which is supported by a common support frame or the like appropriate for each group, and operates integrally for each group during zooming or the like. FIG. 3 also shows a schematic movement trajectory of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end through the intermediate focal length so that the zooming operation can be grasped. This is schematically indicated by an arrow. FIG. 3 also shows the surface number of each optical surface. As mentioned above, each reference numeral for FIG. 3 is also used independently of the other embodiments.
[0081]
In FIG. 3, for example, the first lens E1, the second lens E2, the third lens E3, the aperture FA, the fourth lens E4, the fifth lens E5, the sixth lens E6, and the seventh lens E1 are sequentially arranged from the object side such as a subject. The lens E7, the eighth lens E8, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0082]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a negative meniscus lens formed convex on the object side, and the third lens E3 is a convex surface having a large curvature on the object side. The first group optical system G1 including the first lens E1 to the third lens E3 has a negative focal length as a whole. The fourth lens E4 is a positive meniscus lens formed convex on the object side, the fifth lens E5 is a negative meniscus lens formed convex on the object side, and the sixth lens E6 is formed convex on the object side. The positive meniscus lens and the seventh lens E7 are positive lenses (biconvex lenses), and the fifth lens E5 and the sixth lens E6 are cemented. The second group optical system G2 constituted by E7 has a positive focal length as a whole. The eighth lens E8 is a positive meniscus lens that is formed convex on the object side, and only the eighth lens E8 constitutes a third group optical system G3 having a positive focal length. The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0083]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0084]
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 = 5.97 to 16.86 and F = 2.60 to 4.36, respectively, by zooming. And ω = 39.23 to 15.53. The characteristics of each optical surface are as shown in the following table.
[0085]
[Table 5]
optical properties

[0086]
In Table 5, each of the fourth, eighth, fourteenth, and fifteenth optical surfaces having an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 4th surface
K = 0.0, A₄= −3.74529 × 10^-4, A₆= −7.07111 × 10^-6, A₈= 3.31080 × 10^-7, A₁₀= −2.12578 × 10^-8, A₁₂= 4.72698 × 10^-10, A₁₄= -1.4429 × 10^-12, A₁₆= −1.2287 × 10^-13, A₁₈= 1.26129 × 10^-15
Aspheric surface: 8th surface
K = 0.0, A₄= −9.27221 × 10^-5, A₆= −2.00691 × 10^-7, A₈= −5.999813 × 10^-8, A₁₀= 1.95311 × 10^-9
Aspheric surface: 14th surface
K = 0.0, A₄= 1.17533 × 10^-4, A₆= 1.28941 × 10^-5, A₈= −1.26885 × 10^-6, A₁₀= 6.09645 × 10^-8Aspheric surface: 15th surface
K = 0.0, A₄= -1.91397 x 10^-5, A₆= 3.80313 × 10^-6, A₈= -1.67517 × 10^-7, A₁₀= 3.09028 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0087]
[Table 6]
Variable interval

[0088]
The numerical values of the above-described conditional expressions of the present invention in the third embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
(N₂₂-N₂₃) = 0.288
(Ν₂₃−ν₂₂) = 35.7
((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.66
(L_PN/ L₂) = 0.590
[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 diaphragm FA. And an optical filter OF. In this case, the first lens E1 to the third lens E3 constitute a first group optical system G1, the fourth lens E4 to the seventh lens E7 constitute a second group optical system G2, and the eighth lens E8 , And a third group optical system G3, which is supported by a common support frame or the like appropriate for each group, and operates integrally for each group during zooming or the like. FIG. 4 also shows the general movement trajectory of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end through the intermediate focal length so that the zooming operation can be grasped. This is schematically indicated by an arrow. FIG. 4 also shows the surface number of each optical surface. As described above, each reference numeral for FIG. 4 is used independently of the other embodiments.
[0089]
In FIG. 4, for example, the first lens E1, the second lens E2, the third lens E3, the aperture FA, the fourth lens E4, the fifth lens E5, the sixth lens E6, the seventh lens The lens E7, the eighth lens E8, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0090]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a negative meniscus lens formed convex on the object side, and the third lens E3 is formed convex on the object side. The first group optical system G1 including the first lens E1 to the third lens E3 has a negative focal length as a whole. The fourth lens E4 is a positive meniscus lens formed convex on the object side, the fifth lens E5 is a negative meniscus lens formed convex on the object side, and the sixth lens E6 is formed convex on the object side. The positive meniscus lens and the seventh lens E7 are positive lenses (biconvex lenses), and the fifth lens E5 and the sixth lens E6 are cemented. The second group optical system G2 constituted by E7 has a positive focal length as a whole. The eighth lens E8 is a positive meniscus lens that is formed convex on the object side, and only the eighth lens E8 constitutes a third group optical system G3 having a positive focal length. The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0091]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0092]
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 = 5.97 to 16.88 and F = 2.68 to 4.42, respectively, by zooming. And ω = 39.20 to 15.52. The characteristics of each optical surface are as shown in the following table.
[0093]
[Table 7]
optical properties

[0094]
In Table 7, each of the fourth, eighth, fourteenth, and fifteenth optical surfaces with an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 4th surface
K = 0.0, A₄= −3.502130 × 10^-4, A₆= -8.454561 x 10^-6, A₈= 3.87166 × 10^-7, A₁₀= −2.37791 × 10^-8, A₁₂= 4.886388 × 10^-10, A₁₄= −3.79112 × 10^-13, A₁₆= −1.52048 × 10^-13, A₁₈= 1.32883 × 10^-15
Aspheric surface: 8th surface
K = 0.0, A₄= −9.80638 × 10^-5, A₆= −3.444779 × 10^-7, A₈= −4.47522 × 10^-8, A₁₀= −8.337430 × 10^-10
Aspheric surface: 14th surface
K = 0.0, A₄= 1.835538 × 10^-4, A₆= 6.09812 × 10^-7, A₈= 3.7360 × 10^-7, A₁₀= −1.70939 × 10^-8Aspheric surface: 15th surface
K = 0.0, A₄= −4.21513 × 10^-5, A₆= 2.99547 × 10^-6, A₈= −1.23500 × 10^-7, A₁₀= 2.32351 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0095]
[Table 8]
Variable interval

[0096]
The numerical values of the above-described conditional expressions of the present invention in the fourth embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
(N₂₂-N₂₃) = 0.359
(Ν₂₃−ν₂₂) = 46.7
((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.94
(L_PN/ L₂) = 0.556
[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, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the fourth lens E4 constitute a first group optical system G1, the fifth lens E5 to the eighth lens E8 constitute a second group optical system G2, and the ninth lens E9 , And a third group optical system G3, each of which is supported by an appropriate common support frame or the like for each group, and operates integrally for each group during zooming or the like. FIG. 5 also shows a schematic movement trajectory of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end through the intermediate focal length so that the zooming operation can be grasped. This is schematically indicated by an arrow. FIG. 5 also shows the surface number of each optical surface. As mentioned above, each reference numeral for FIG. 5 is also used independently of the other embodiments.
[0097]
In FIG. 5, for example, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the aperture FA, the fifth lens E5, the sixth lens E6, and the seventh lens E1 are sequentially arranged from the object side such as a subject. The lens E7, the eighth lens E8, the ninth lens E9, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0098]
The first lens E1 has a negative meniscus lens convexly formed on the object side, the second lens E2 has a negative meniscus lens formed convexly on the object side, and the third lens E3 has a convex surface having a large curvature on the object side. The positive lens (biconvex lens) and the fourth lens E4 are a negative lens (biconcave lens), and the third lens E3 and the fourth lens E4 are cemented. The first group optical system G1 including the E1 to the fourth lens E4 has a negative focal length as a whole. The fifth lens E5 is a positive meniscus lens formed convex on the object side, the sixth lens E6 is a negative meniscus lens formed convex on the object side, and the seventh lens E7 is formed convex on the object side. The positive meniscus lens and the eighth lens E8 are positive lenses (biconvex lenses), and the sixth lens E6 and the seventh lens E7 are cemented together. The second group optical system G2 constituted by E8 exhibits a positive focal length as a whole. The ninth lens E9 is a positive lens (biconvex lens) having a convex surface with a large curvature directed toward the object side, and the ninth lens E9 alone constitutes a third group optical system G3 having a positive focal length. . The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0099]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0100]
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 = 5.98 to 16.89 and F = 2.62 to 4.51, respectively, by zooming. , And ω = 39.18 to 15.52. The characteristics of each optical surface are as shown in the following table.
[0101]
[Table 9]
optical properties

[0102]
In Table 9, each of the fourth, ninth, fifteenth, and sixteenth optical surfaces having an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 4th surface
K = 0.0, A₄= -3.91323 × 10^-4, A₆= −7.49996 × 10^-6, A₈= 3.1143 × 10^-7, A₁₀= -1.90421 × 10^-8, A₁₂= 3.9129 × 10^-10, A₁₄= −2.01103 × 10^-12, A₁₆= −5.49008 × 10^-14, A₁₈= 3.197870 × 10^-16
Aspheric surface: 9th surface
K = 0.0, A₄= −9.62105 × 10^-5, A₆= −9.77873 × 10^-7, A₈= 1.62625 × 10^-8, A₁₀= −8.46903 × 10^-10
Aspheric surface: 15th surface
K = 0.0, A₄= 1.62639 × 10^-4, A₆= 2.90705 × 10^-5, A₈= −3.668616 × 10^-6, A₁₀= 2.00067 × 10^-7Aspheric surface: 16th surface
K = 0.0, A₄= −1.57048 × 10^-5, A₆= 5.232426 × 10^-6, A₈= −2.39620 × 10^-7, A₁₀= 4.62003 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0103]
[Table 10]
Variable interval

[0104]
The numerical values of the conditional expressions of the present invention described above in the fifth embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
(N₂₂-N₂₃) = 0.208
(Ν₂₃−ν₂₂) = 31.7
((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.86
(L_PN/ L₂) = 0.498
[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, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the fourth lens E4 constitute a first group optical system G1, the fifth lens E5 to the eighth lens E8 constitute a second group optical system G2, and the ninth lens E9 , And a third group optical system G3, each of which is supported by an appropriate common support frame or the like for each group, and operates integrally for each group during zooming or the like. FIG. 5 also shows a schematic movement trajectory of each group from the short focal length end at the wide angle end to the long focal length end at the telephoto end through the intermediate focal length so that the zooming operation can be grasped. This is schematically indicated by an arrow. FIG. 6 also shows the surface number of each optical surface. As mentioned above, each reference numeral for FIG. 6 is also used independently of the other embodiments.
[0105]
In FIG. 6, for example, the first lens E1, the second lens E2, the third lens E3, the fourth lens E4, the aperture FA, the fifth lens E5, the sixth lens E6, and the seventh lens E1 are sequentially arranged from the object side such as a subject. The lens E7, the eighth lens E8, the ninth lens E9, and the optical filter OF are arranged in this order, and an image is formed behind the optical filter OF having various optical filtering functions.
[0106]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a negative meniscus lens formed convex on the object side, and the third lens E3 is formed convex on the object side. The negative meniscus lens and the fourth lens E4 are positive meniscus lenses formed to be convex on the object side, and the first group optical system G1 configured by the first lens E1 to the fourth lens E4 having four groups and four elements. Exhibits a negative focal length as a whole. The fifth lens E5 is a positive meniscus lens formed convex on the object side, the sixth lens E6 is a negative meniscus lens formed convex on the object side, and the seventh lens E7 is formed convex on the object side. The positive meniscus lens and the eighth lens E8 are positive lenses (biconvex lenses), and the sixth lens E6 and the seventh lens E7 are cemented together. The second group optical system G2 constituted by E8 exhibits a positive focal length as a whole. The ninth lens E9 is a positive meniscus lens convexly formed on the object side. The ninth lens E9 alone forms a third group optical system G3 having a positive focal length. The aperture stop FA arranged on the object side of the second group optical system G2 operates integrally with the second group optical system G2.
[0107]
Upon zooming from the short focal end to the long focal end, the second group optical system G2, which mainly has a zoom function, monotonously moves from the image side to the object side, and the first group optical system G1 shifts the image accompanying the zooming. The third group optical system moves to correct the fluctuation of the surface position, and operates mainly to keep the exit pupil away from the image plane. More specifically, the distance between the first group optical system G1 and the second group optical system G2 is gradually reduced with zooming from the short focus end to the long focus end, and the second group optical system G2 and the third The optical systems of each group are moved so as to gradually increase the interval between the group optical systems G3.
[0108]
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 = 5.97 to 16.88 and F = 2.63 to 4.45 due to zooming, respectively. And ω = 39.20 to 15.52. The characteristics of each optical surface are as shown in the following table.
[0109]
[Table 11]
optical properties

[0110]
In Table 9, each of the sixth, tenth, sixteenth, and seventeenth optical surfaces having an asterisk “*” added to the surface number is an aspheric surface, and the parameters of each aspheric surface are as follows.
Aspheric surface: 6th surface
K = 0.0, A₄= −3.777077 × 10^-4, A₆= −7.57114 × 10^-6, A₈= 3.24559 × 10^-7, A₁₀= −2.06841 × 10^-8, A₁₂= 4.43898 × 10^-10, A₁₄= −1.723365 × 10^-12, A₁₆= −9.21068 × 10^-14, A₁₈= 7.60642 × 10^-16
Aspheric surface: 10th surface
K = 0.0, A₄= −9.000752 × 10^-5, A₆= 3.09052 × 10^-8, A₈= −7.16556 × 10^-8, A₁₀= 2.2617 × 10^-9
Aspheric surface: 16th surface
K = 0.0, A₄= 1.02677 × 10^-4, A₆= 1.82551 × 10^-5, A₈= -1.97083 × 10^-6, A₁₀= 9.81276 × 10^-8Aspheric surface: 17th surface
K = 0.0, A₄= −1.59462 × 10^-5, A₆= 4.776213 × 10^-6, A₈= −2.242929 × 10^-7, A₁₀= 4.30948 × 10^-9
Distance D between aperture stop FA integrated with first group optical system G1 and second group optical system G2_A, The distance D between the second group optical system G2 and the third group optical system G3_BAnd the distance D between the third group optical system G3 and the optical filter OF_CAre variable, and these variable intervals D_A~ D_CIs changed as shown in the following table during zooming.
[0111]
[Table 12]
Variable interval

[0112]
The numerical values of the above-described conditional expressions of the present invention in the sixth embodiment are as follows, and are within the range of each conditional expression.
Conditional expression
(N₂₂-N₂₃) = 0.258
(Ν₂₃−ν₂₂) = 37.5
((1 / r_21F) + (1 / r_22F) + (1 / r_22R)) × Y ′) = 1.80
(L_PN/ L₂) = 0.538
7 to 9 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 1 according to the first embodiment described above. FIG. FIG. 8 is an aberration curve at an intermediate focal length, and FIG. 9 is an aberration curve at a long focal end. In each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
10 to 12 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 2 according to the second embodiment described above. FIG. FIG. 11 is an aberration curve at an intermediate focal length, and FIG. 12 is an aberration curve at a long focal end. Also in this case, in each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
[0113]
FIGS. 13 to 15 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 3 according to the third embodiment described above. FIG. 14 is an aberration curve at the intermediate focal length, and FIG. 15 is an aberration curve at the long focal end. Also in this case, in each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
16 to 18 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 4 according to the fourth embodiment described above. FIG. FIG. 17 is an aberration curve diagram at an intermediate focal length, and FIG. 18 is an aberration curve diagram at a long focal end. Also in this case, in each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
19 to 21 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 5 according to the fifth embodiment described above, and FIG. FIG. 20 is an aberration curve diagram at the intermediate focal length, and FIG. 21 is an aberration curve diagram at the long focal end. Also in this case, in each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
FIGS. 22 to 24 show aberration curves of spherical aberration, astigmatism, distortion, and coma in the zoom lens shown in FIG. 6 according to the sixth embodiment described above. FIG. 23 is an aberration curve at an intermediate focal length, and FIG. 24 is an aberration curve at a long focal end. Also in this case, in each aberration curve diagram, a broken line in the spherical aberration diagram represents a sine condition, a solid line in the astigmatism diagram represents sagittal, and a broken line represents meridional.
According to the aberration curve diagrams in FIGS. 7 to 24, according to the zoom lenses having the configurations shown in FIGS. 1 to 6 according to the above-described first to sixth embodiments of the present invention, all aberrations are reduced. It can be seen that the correction has been made well or suppressed.
[0114]
[Seventh embodiment]
Next, a seventh embodiment of the present invention in which a camera is configured by employing a zoom lens according to the present invention as shown in the above-described first to sixth embodiments as a photographing optical system will be described with reference to FIGS. This will be described with reference to FIG. FIG. 25 is a perspective view showing the appearance of the camera viewed from the front side which is the object, that is, the subject side. FIG. 26 is a perspective view showing the appearance of the camera viewed from the back side which is the photographer side. FIG. 2 is a block diagram showing a functional configuration of the camera. Although a camera is described here, a device in which a camera function is incorporated in a portable information terminal device such as a so-called PDA (personal data assistant) or a mobile phone has recently appeared. Although such a portable information terminal device also has a slightly different appearance, it has substantially the same functions and configurations as a camera, and even if the zoom lens according to the present invention is employed in such a portable information terminal device. Good.
[0115]
As shown in FIGS. 25 and 26, the camera includes a taking lens 101, a shutter button 102, a zoom lever 103, a finder 104, a strobe 105, a liquid crystal monitor 106, an operation button 107, a power switch 108, a memory card slot 109, and a communication card. A slot 110 and the like are provided. Further, as shown in FIG. 27, the camera also includes a light receiving element 201, a signal processing device 202, an image processing device 203, a central processing unit (CPU) 204, a semiconductor memory 205, a communication card 206, and the like.
The camera has a photographing lens 101 and a light receiving element 201 as an area sensor such as a CCD (Charge Coupled Device) image pickup element. An object to be photographed formed by the photographing lens 101 as a photographing optical system, that is, a subject , Are read by the light receiving element 201. As the photographing lens 101, a zoom lens according to the present invention (that is, defined by claims 1 to 9) as described in the first to sixth embodiments is used (claims 10 and 11). Corresponding to).
[0116]
The output of the light receiving element 201 is processed by a signal processing device 202 controlled by a central processing unit 204 and converted into digital image information. The image information digitized by the signal processing device 202 is subjected to predetermined image processing in an image processing device 203 also controlled by a central processing unit 204, and then recorded in a semiconductor memory 205 such as a nonvolatile memory. In this case, the semiconductor memory 205 may be a memory card inserted in the memory card slot 109 or a semiconductor memory built in the camera body. On the liquid crystal monitor 106, an image being captured can be displayed, and an image recorded in the semiconductor memory 205 can be displayed. Further, the image recorded in the semiconductor memory 205 can be transmitted to the outside via a communication card 206 or the like inserted in the communication card slot 110.
[0117]
When the camera is carried, the photographing lens 101 is in a collapsed state and is buried in the body of the camera as shown in FIG. 25A. (B), the lens barrel is extended and projected from the camera body. At this time, inside the lens barrel of the taking lens 101, the optical systems of the respective groups constituting the zoom lens are arranged, for example, at the short focal length end. The arrangement is changed, and a zooming operation to the long focal end can be performed. Preferably, the viewfinder 104 also changes magnification in response to a change in the angle of view of the photographing lens 101.
In many cases, focusing is performed by half-pressing the shutter button 102. Focusing in a zoom lens composed of three groups of negative-positive-positive as shown in the first to sixth embodiments described above is performed by moving the first group optical system G1 or the third group optical system G3. Alternatively, it can be performed by moving the light receiving element 201. When the shutter button 102 is further depressed to a fully depressed state, photographing is performed, and then the above-described processing is performed.
[0118]
When displaying the image recorded in the semiconductor memory 205 on the liquid crystal monitor 106 or transmitting the image to the outside via the communication card 206 or the like, the operation button 107 is operated as predetermined. The semiconductor memory 205 and the communication card 206 are used by being loaded into dedicated or general-purpose slots such as the memory card slot 109 and the communication card slot 110, respectively.
As described above, in the camera or the portable information terminal device as described above, the zoom lens as shown in the first to sixth embodiments can be used as the photographing optical system. Therefore, it is possible to achieve a high-quality, small-sized camera or portable information terminal device using a light receiving element in a class of 3 to 6 million pixels.
[0119]
The present invention will be summarized based on the above-described embodiments according to each claim. The zoom lens according to claim 1 of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
[0120]
Then, the refractive index of the negative meniscus lens of the second group optical system is set to N₂₂, The refractive index of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
0.15 <(N₂₂-N₂₃) <0.40
To be satisfied.
According to the configuration of the first aspect, it is possible to provide a zoom lens that is sufficiently small, has a wide angle of view, has high performance, and has a resolution corresponding to an image sensor having 3 to 6 million pixels. As a result, a small-sized camera with a wide angle of view and high image quality or a portable information terminal device can be realized.
[0121]
The zoom lens according to claim 2 of the present invention includes:
The zoom lens according to claim 1,
The Abbe number of the negative meniscus lens in the second group optical system is ν₂₂, The Abbe number of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
25 <(ν₂₃  −ν₂₂  ) <50
To be satisfied.
[0122]
According to the configuration of the second aspect, it is possible to provide a high-performance zoom lens in which chromatic aberration is more favorably corrected, and as a result, a camera or a portable information terminal device with higher image quality can be realized.
[0123]
The zoom lens according to claim 3 of the present invention includes:
The zoom lens according to claim 1 or 2,
The radius of curvature of the object side surface of the most object side positive lens in the second group optical system is r_21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
To be satisfied.
[0124]
According to the configuration of the third aspect, it is possible to provide a high-performance zoom lens in which the curvature of field is corrected more favorably, and as a result, the image quality is less deteriorated even around the screen, and the camera or the mobile phone has higher image quality. An information terminal device can be realized.
[0125]
The zoom lens according to claim 4 of the present invention includes:
The zoom lens according to any one of claims 1 to 3,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
To be satisfied.
[0126]
According to the configuration of the fourth aspect, it is possible to provide a higher-performance zoom lens in which spherical aberration, astigmatism, and coma aberration are more properly corrected, and as a result, a high-quality camera having higher resolution. Alternatively, a portable information terminal device can be realized.
The zoom lens according to claim 5 of the present invention includes:
In the zoom lens according to any one of claims 1 to 4,
The curvature of the joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all the surfaces of the second group optical system.
[0127]
According to the configuration of claim 5, it is possible to provide a high-performance zoom lens in which monochromatic aberration and chromatic aberration are balanced, and as a result, a high-quality camera or portable information with less color bleeding even at the peripheral portion of the screen. A terminal device can be realized.
[0128]
The zoom lens according to claim 6 of the present invention includes:
The zoom lens according to any one of claims 1 to 5,
The most object side surface and the most image side surface of the second group optical system are aspherical surfaces.
[0129]
According to the configuration of the sixth aspect, it is possible to provide a higher-performance zoom lens in which the monochromatic aberration is corrected more favorably, thereby realizing a camera or a portable information terminal device with higher image quality over the entire screen. Can be.
[0130]
The zoom lens according to claim 7 of the present invention includes:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
[0131]
Then, the radius of curvature of the object side surface of the positive lens closest to the object in the second group optical system is represented by r._21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
To be satisfied.
[0132]
Also, the zoom lens according to claim 8 of the present invention,
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
To be satisfied.
[0133]
Furthermore, a zoom lens according to claim 9 of the present invention is:
A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The curvature of the joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all the surfaces of the second group optical system.
[0134]
According to the configuration of claims 7 to 9, a zoom lens having a sufficiently small size, a wide angle of view, high performance, and a resolution corresponding to an image sensor having 3 to 6 million pixels is realized. It is possible to provide a camera or a portable information terminal device that is small, has a wide angle of view, and has high image quality.
[0135]
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.
[0136]
According to the configuration of claim 10, a zoom lens having a sufficiently small size, a wide angle of view, high performance, and a resolution corresponding to an image sensor having 3 to 6 million pixels is used as a photographing optical system. As a result, a small, wide-angle, high-quality camera can be provided, and as a result, the user can shoot a high-quality image with a camera having excellent portability.
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.
[0137]
According to the configuration of the eleventh aspect, a zoom lens having a sufficiently small size, a wide angle of view, high performance, and a resolution corresponding to an image sensor having 3 to 6 million pixels is photographed by the camera function unit. It can be used as an optical system to provide a small, high-quality portable information terminal device. As a result, a user can take a high-quality image with a portable information terminal device with excellent portability and send the image to the outside. Can be sent.
[0138]
【The invention's effect】
As described above, according to the present invention, at least a first group optical system having a negative focal length and a second group optical system having a positive focal length are sequentially arranged from the object side, and The zoom lens has a stop that moves integrally with the second group optical system, and when zooming from the short focus end to the long focus end, the second group optical system moves monotonously from the image side to the object side, The first-group optical system has a sufficiently small size and a wide angle of view by using a configuration in which the first-group optical system moves so as to correct a change in the image plane position caused by zooming. It is possible to provide a zoom lens, a camera, and a portable information terminal device having a high resolution.
[0139]
That is, according to the zoom lens of the first aspect of the present invention, from the object side, the first group optical system having a negative focal length, the second group optical system having a positive focal length, and the positive focal length A third group optical system having the following arrangement, and a stop which moves integrally with the second group optical system on the object side of the second group optical system. At the time of zooming, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system gradually increases. In the zoom lens in which the first-group optical system to the third-group optical system move, the second-group optical system sequentially turns, from the object side, a positive lens having a surface with a large curvature toward the object side, and a concave surface toward the image side. Negative meniscus lens, positive meniscus lens joined to the negative meniscus lens, and positive lens Consists optics sequences has been made 3 groups four lenses, and the refractive index of the negative meniscus lens of the second group optical system N₂₂, The refractive index of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
0.15 <(N₂₂-N₂₃) <0.40
Is satisfied, the first group optical system having a negative focal length and the second group optical system having a positive focal length are sequentially arranged at least from the object side, and the second group optical system is The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to compensate for a change in the image plane position caused by zooming, it is possible to obtain a sufficiently small size and a wide angle of view, and to perform high-performance imaging of 3 to 6 million pixels. The resolution corresponding to the element can be obtained.
[0140]
According to the zoom lens of the present invention, the Abbe number of the negative meniscus lens in the second group optical system is ν.₂₂, The Abbe number of the positive meniscus lens joined to the negative meniscus lens₂₃As
Conditional expression:
25 <(ν₂₃  −ν₂₂  ) <50
Is satisfied, in particular, chromatic aberration can be corrected more favorably, and the performance can be further improved.
[0141]
According to the zoom lens of the third aspect of the present invention, in the zoom lens of the first or second aspect, the radius of curvature of the object side surface of the most object side positive lens in the second group optical system is r._21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
In particular, the field curvature can be corrected more favorably, and the performance can be further improved.
[0142]
According to the zoom lens of the fourth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the vertex on the object side surface of the most object-side positive lens of the second group optical system. Is the distance from the vertex of the joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system to L._PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
In particular, the spherical aberration, astigmatism, and coma aberration can be more favorably corrected to achieve higher performance.
[0143]
According to the zoom lens according to claim 5 of the present invention, in the zoom lens according to any one of claims 1 to 4, the negative meniscus lens and the positive meniscus lens of the second group optical system are connected. With the configuration in which the curvature of the cemented surface is the largest among all the surfaces of the second group optical system, in particular, the monochromatic aberration and the chromatic aberration can be balanced, and the performance can be further improved.
[0144]
According to the zoom lens of the sixth aspect of the present invention, in the zoom lens of any one of the first to fifth aspects, the most object-side surface and the most image-side surface of the second group optical system. Is an aspherical surface, and in particular, it is possible to further mainly correct monochromatic aberration more favorably and to achieve higher performance.
[0145]
According to the zoom lens of the seventh aspect of the present invention, the first group optical system having a negative focal length, the second group optical system having a positive focal length, and the positive focal length are sequentially arranged from the object side. A third group optical system having the same, and a stop which moves integrally with the second group optical system on the object side of the second group optical system. At the time of magnification, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system gradually increases. In the zoom lens in which the group optical system to the third group optical system move, the second group optical system has a positive lens having a surface with a large curvature directed to the object side and a concave surface directed to the image side sequentially from the object side. The negative meniscus lens, the positive meniscus lens joined to the negative meniscus lens, and the positive lens are arranged. It consists of three groups of four configurations optical system comprising Te, and the radius of curvature of the object side surface of the most object side of the positive lens in the second group optical system r_21FThe radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r_22FThe radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the second group optical system is r_22RAnd the maximum image height is Y ′
Conditional expression:
1.40
<((1 / r_21F  ) + (1 / r_22F) + (1 / r_22R)) × Y ')
<2.20
Is satisfied, the first group optical system having a negative focal length and the second group optical system having a positive focal length are sequentially arranged at least from the object side, and the second group optical system is The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to correct the fluctuation of the image plane position due to zooming, it is possible to obtain a sufficiently small size and a wide angle of view, and at the same time, it is high-performance and mainly has a good field curvature. By performing the correction, it is possible to obtain a resolution corresponding to an image sensor having 3 to 6 million pixels.
[0146]
According to the zoom lens of the eighth aspect of the present invention, the first group optical system having a negative focal length, the second group optical system having a positive focal length, and the positive focal length are sequentially arranged from the object side. A third group optical system having the same, and a stop which moves integrally with the second group optical system on the object side of the second group optical system. At the time of magnification, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system gradually increases. In the zoom lens in which the group optical system to the third group optical system move, the second group optical system has a positive lens having a surface with a large curvature directed to the object side and a concave surface directed to the image side sequentially from the object side. The negative meniscus lens, the positive meniscus lens joined to the negative meniscus lens, and the positive lens are arranged. And a negative meniscus lens and a positive meniscus lens of the second group optical system from the vertex of the object side surface of the most object side positive lens of the second group optical system. Distance to the vertex of the joint surface with_PN, The thickness of the second group optical system in the optical axis direction is L₂As
Conditional expression:
0.40 <(L_PN/ L₂) <0.70
Is satisfied, the first group optical system having a negative focal length and the second group optical system having a positive focal length are sequentially arranged at least from the object side, and the second group optical system is The second group optical system monotonously moves from the image side to the object side when the magnification is changed from the short focal end to the long focal end, with a stop that moves integrally. By using a configuration that moves so as to correct a change in the image plane position caused by zooming, a sufficiently small size and a wide angle of view can be obtained, and high performance is obtained, and spherical aberration, astigmatism and By properly correcting coma, it is possible to obtain a resolution corresponding to an image sensor having 3 to 6 million pixels.
[0147]
According to the zoom lens of the ninth aspect of the present invention, the first group optical system having a negative focal length, the second group optical system having a positive focal length, and the positive focal length are sequentially arranged from the object side. A third group optical system having the same, and a stop which moves integrally with the second group optical system on the object side of the second group optical system. At the time of magnification, the distance between the first group optical system and the second group optical system gradually decreases, and the distance between the second group optical system and the third group optical system gradually increases. In the zoom lens in which the group optical system to the third group optical system move, the second group optical system has a positive lens having a surface with a large curvature directed to the object side and a concave surface directed to the image side sequentially from the object side. The negative meniscus lens, the positive meniscus lens joined to the negative meniscus lens, and the positive lens are arranged. And a curvature of a joining surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is equal to that of all surfaces of the second group optical system. The first group optical system having a negative focal length and the second group optical system having a positive focal length are arranged at least sequentially from the object side; The second group optical system monotonously moves from the image side to the object side when zooming from the short focal end to the long focal end. Is capable of obtaining a sufficiently small size and a wide angle of view by using a configuration that moves so as to correct a change in the image plane position caused by zooming, and has high performance. The balance is good, and it is possible to obtain the resolution corresponding to the image sensor with 3 to 6 million pixels. Can.
[0148]
According to the camera of the tenth aspect of the present invention, by including the zoom lens according to any one of the first to ninth aspects as a photographic optical system, the camera is sufficiently small and has a wide angle of view. And a high-performance zoom lens capable of obtaining a resolving power corresponding to an image sensor having 3 to 6 million pixels can be used as a photographing optical system to obtain a compact and high image quality.
[0149]
According to the portable information terminal device of the eleventh aspect of the present invention, the configuration including the zoom lens according to any one of the first to ninth aspects as a photographing optical system of the camera function unit is sufficient. Using a zoom lens, which is compact and can obtain a wide angle of view, is high-performance, and obtains a resolving power corresponding to an image sensor of 3 to 6 million pixels, as a photographing optical system of a camera function unit, Small size and high image quality can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along an optical axis schematically showing a configuration of an optical system of a zoom lens according to a first example of the present invention.
FIG. 2 is a cross-sectional view along an optical axis schematically illustrating a configuration of an optical system of a zoom lens according to a second example of the present invention.
FIG. 3 is a cross-sectional view along an optical axis schematically showing a configuration of an optical system of a zoom lens according to a third example of the present invention.
FIG. 4 is a cross-sectional view along an optical axis schematically showing a configuration of an optical system of a zoom lens according to a fourth example of the present invention.
FIG. 5 is a cross-sectional view along an optical axis schematically showing a configuration of an optical system of a zoom lens according to a fifth example of the present invention.
FIG. 6 is a cross-sectional view along an optical axis schematically showing a configuration of an optical system of a zoom lens according to Example 6 of the present invention.
FIG. 7 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the first embodiment of the present invention shown in FIG.
FIG. 8 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at an intermediate focal length of the zoom lens according to the first embodiment of the present invention shown in FIG.
FIG. 9 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to the first embodiment of the present invention shown in FIG.
FIG. 10 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the second embodiment of the present invention shown in FIG.
FIG. 11 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at an intermediate focal length of the zoom lens according to the second embodiment of the present invention shown in FIG.
FIG. 12 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to the second embodiment of the present invention shown in FIG.
FIG. 13 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the third embodiment of the present invention shown in FIG.
FIG. 14 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at an intermediate focal length of the zoom lens according to the third embodiment of the present invention shown in FIG.
FIG. 15 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to the third embodiment of the present invention shown in FIG.
FIG. 16 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the fourth embodiment of the present invention shown in FIG.
FIG. 17 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at an intermediate focal length of the zoom lens according to the fourth embodiment of the present invention shown in FIG.
FIG. 18 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to the fourth embodiment of the present invention shown in FIG.
FIG. 19 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the fifth embodiment of the present invention shown in FIG.
FIG. 20 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the intermediate focal length of the zoom lens according to the fifth embodiment of the present invention shown in FIG.
FIG. 21 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to a fifth embodiment of the present invention shown in FIG.
FIG. 22 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the short focal length end of the zoom lens according to the sixth embodiment of the present invention shown in FIG.
FIG. 23 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at an intermediate focal length of the zoom lens according to the sixth embodiment of the present invention shown in FIG.
FIG. 24 is an aberration curve diagram showing spherical aberration, astigmatism, distortion, and coma aberration at the long focal end of the zoom lens according to the sixth embodiment of the present invention shown in FIG.
FIG. 25 is a perspective view schematically showing the external configuration of a camera according to a seventh embodiment of the present invention, as viewed from the object side, and FIG. 25 (a) shows a photographing lens retracted and buried in the body of the camera. (B) shows a state in which the taking lens is protruding from the body of the camera.
26 is a perspective view schematically showing the external configuration of the camera of FIG. 25, as viewed from the photographer side.
FIG. 27 is a block diagram schematically showing a functional configuration of the camera in FIG. 25.
[Explanation of symbols]
G1 First group optical system
G2 Second group optical system
G3 Third group optical system
E1-E9 lens
FA aperture
OF Various optical filters
101 Shooting lens
102 Shutter button
103 Zoom lever
104 Finder
105 Strobe
106 LCD monitor
107 operation buttons
108 Power switch
109 Memory card slot
110 Communication card slot
201 Light receiving element (area sensor)
202 Signal processing device
203 Image processing device
204 Central Processing Unit (CPU)
205 Semiconductor Memory
206 Communication card, etc.

Claims (11)

A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
Then, the refractive index N ₂₂ of the second group optical system and the negative meniscus _lens, the refractive index of said positive meniscus lens cemented to a negative meniscus lens as N _23,
Conditional expression:
_{0.15 <(N 22 -N 23)} <0.40
A zoom lens characterized by satisfying the following. The Abbe number of the negative meniscus lens in the second group optical system is ν ₂₂ , and the Abbe number of the positive meniscus lens joined to the negative meniscus lens is ν ₂₃ ,
Conditional expression:
25 <(ν ₂₃ −ν ₂₂ ) <50
The zoom lens according to claim 1, wherein the following condition is satisfied. The radius of curvature of the object side surface of the positive lens closest to the object side in the second group optical system is r _21F , the radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r _22F , and the second group optical system is , The radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens is r _22R , and the maximum image height is Y ′.
Conditional expression:
1.40
<((1 / r _21F ) + (1 / r _22F ) + (1 / r _22R )) × Y ′)
<2.20
The zoom lens according to claim 1 or 2, wherein the following formula is satisfied. The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L _PN , the thickness of the optical axis of the second group optical system as L _2,
Conditional expression:
0.40 <(L _PN / L ₂ ) <0.70
The zoom lens according to any one of claims 1 to 3, wherein the following formula is satisfied. The curvature of a joining surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all surfaces of the second group optical system. The zoom lens according to any one of the four items. The zoom lens according to any one of claims 3 to 5, wherein a surface closest to the object and a surface closest to the image of the second group optical system are aspherical. A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The radius of curvature of the object side surface of the positive lens closest to the object side in the second group optical system is r _21F , the radius of curvature of the object side surface of the negative meniscus lens in the second group optical system is r _22F , and the second group is The radius of curvature of the junction surface between the negative meniscus lens and the positive meniscus lens in the optical system is r _22R , and the maximum image height is Y ′.
Conditional expression:
1.40
<((1 / r _21F ) + (1 / r _22F ) + (1 / r _22R )) × Y ′)
<2.20
A zoom lens characterized by satisfying the following. A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
The distance from the vertex of the object side surface of the positive lens closest to the object side of the second group optical system to the vertex of the junction surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is L _PN , the thickness of the optical axis direction of the second group optical system as L _2,
Conditional expression:
0.40 <(L _PN / L ₂ ) <0.70
A zoom lens characterized by satisfying the following. A first group optical system having a negative focal length, a second group optical system having a positive focal length, and a third group optical system having a positive focal length are sequentially arranged from the object side; A stop that moves integrally with the second group optical system on the object side of the second group optical system;
At the time of zooming from the short focal end to the long focal end, the distance between the first group optical system and the second group optical system becomes gradually smaller, and the distance between the second group optical system and the third group optical system becomes smaller. In the zoom lens in which the first group optical system to the third group optical system move so that
The second group optical system, in order from the object side, a positive lens with a large surface of curvature facing the object side, a negative meniscus lens with a concave surface facing the image side, a positive meniscus lens joined to the negative meniscus lens, and It consists of an optical system of three groups and four elements in which positive lenses are arranged,
A zoom lens, wherein a curvature of a joint surface between the negative meniscus lens and the positive meniscus lens of the second group optical system is the largest among all surfaces of the second group optical system. A camera comprising the zoom lens according to claim 1 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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