JP2005043607A - Zoom lens, camera, portable information terminal device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a compact and high speed zoom lens having high variable power from sufficiently wide angle side and a high resolution with a small number of lens elements at a low cost, in a zoom lens using a constitution of five lens groups or more successively arranged, from the object side, a positive first lens group G1, a negative second lens group G2, a positive third lens group G3, a positive fourth lens group G4 and a positive fifth lens group G5. <P>SOLUTION: The second lens group G2 includes a negative lens of which the strong aspherical concave face is directed to the image side, and the variable power action is performed by moving at least the second lens group G2, the third lens group G3 and the fourth lens group G4. In the variation in power from the wide angle end to a telescopic end, the distance between the first lens group G1 and the second lens group G2 is made larger and the distance between the second lens group G2 and the third lens group G3 decreases and the distance between the third lens group G3 and the fourth lens group G4 is made smaller. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３５】
〔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は、第１レンズ群Ｇ１を構成し、第２レンズＥ２および第３レンズＥ３は、第２レンズ群Ｇ２を構成し、第４レンズＥ４は、第３レンズ群Ｇ３を構成し、第５レンズＥ５〜第７レンズＥ７は、第４レンズ群Ｇ４を構成し、そして第８レンズＥ８は、第５レンズ群Ｇ５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、各光学面の面番号も示している。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、そのため図２〜図４と共通の参照符号を付していてもそれらは他の実施例とはかならずしも共通の構成ではない。
【００３６】
図１において、ズームレンズの光学系を構成する各光学要素は、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。
第１レンズＥ１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１レンズＥ１により構成する第１レンズ群Ｇ１は、正の焦点距離を呈する。すなわち、この第１レンズ群Ｇ１は、第１レンズＥ１からなる１枚の正レンズのみによって構成している。第２レンズＥ２は、物体側に凸に形成され、像面側の強い凹面を非球面とした、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２レンズＥ２および第３レンズＥ３により構成する第２レンズ群Ｇ２は、全体として負の焦点距離を呈する。すなわち、これら第２レンズＥ２および第３レンズＥ３は、それぞれ像面側に非球面からなる強い凹面を向けた負レンズおよび物体側に凸面を向けた正レンズに相当する。第４レンズＥ４は、物体側に凸に形成され、物体側の強い凸面を非球面とした、正メニスカスレンズであり、この第４レンズＥ４により構成する第３レンズ群Ｇ３は、正の焦点距離を呈する。
【００３７】
すなわち、この第３レンズ群Ｇ３は、非球面からなる凸面を物体側に向けた第４レンズＥ４からなる正レンズを含んでいる。第３レンズ群Ｇ３の物体側に配置された絞りＦＡは、第３レンズ群Ｇ３と一体的に動作する。第５レンズＥ５は、物体側に強い凸面を向けた両凸レンズからなる正レンズ、そして第６レンズＥ６は、像面側に強い凹面を向けた両凹レンズからなる負レンズであり、これら第５レンズＥ５および第６レンズＥ６は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。さらに第７レンズＥ７は、物体側に強い凸面を向けた両凸レンズからなり、像面側の凸面を非球面とした正レンズである。これら２群３枚構成の第５レンズＥ５〜第７レンズＥ７により構成する第４レンズ群Ｇ４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、物体側の強い凸面を非球面とした、正メニスカスレンズであり、この第８レンズＥ８により構成する第５レンズ群Ｇ５は、正の焦点距離を呈する。すなわち、この第５レンズ群Ｇ５は、第８レンズＥ８からなる１枚の正レンズのみによって構成している。
【００３８】
広角端（すなわち短焦点端）から望遠端（すなわち長焦点端）への変倍に際しては、各群間の可変間隔、すなわち、第１レンズ群Ｇ１の最も像面側の面、つまり第１レンズＥ１の像面側の面（面番号２）と、第２レンズ群Ｇ２の最も物体側の面、つまり第２レンズＥ２の物体側の面（面番号３）との間隔Ｄ２、第２レンズ群Ｇ２の最も像面側の面、つまり第３レンズＥ３の像面側の面（面番号６）と、第３レンズ群Ｇ３に一体化された絞りＦＡの（物体側の）面（面番号７）との間隔Ｄ６、第３レンズ群Ｇ３の最も像面側の面、つまり第４レンズＥ４の像面側の面（面番号９）と、第４レンズ群Ｇ４の最も物体側の面、つまり第５レンズＥ５の物体側の面（面番号１０）との間隔Ｄ９、第４レンズ群Ｇ４の最も像面側の面、つまり第７レンズＥ７の像面側の面（面番号１４）と、第５レンズ群Ｇ５の最も物体側の面、つまり第８レンズＥ８の物体側の面（面番号１５）との間隔Ｄ１４および第５レンズ群Ｇ５の最も像面側の面、つまり第８レンズＥ８の像面側の面（面番号１６）と光学フィルタＯＦの物体側の面（面番号１７）との間隔Ｄ１６が変化して、第１レンズ群Ｇ１と第２レンズ群Ｇ２の間隔Ｄ２が漸次大きくなり、第２レンズ群Ｇ２と第３レンズ群Ｇ３の間隔Ｄ６が漸次小さくなり、第３レンズ群Ｇ３と第４レンズ群Ｇ４の間隔Ｄ９が漸次小さくなり、第４レンズ群Ｇ４と第５レンズ群Ｇ５の間隔Ｄ１４が漸次大きくなり、そして第５レンズ群Ｇ５と光学フィルタＯＦの間隔Ｄ１６が一旦小さくなってから再び大きくなるように、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第３レンズ群Ｇ３、第４レンズ群Ｇ４および第５レンズ群Ｇ５が移動する。
【００３９】
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，半画角ωが、ズーミングによって、それぞれｆ＝５．８〜１７．４，Ｆ＝２．８１〜４．５０，ω＝３７．５０〜１４．５８の範囲で変化する。各光学面の特性は、次表の通りである。
【００４０】
【表１】
光学特性

【００４１】
表１に示すように第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（２）式におけるパラメータは次の通りである。
非球面：第４面
Ｋ＝−１．３２４２７
Ｅ_４＝３．１３１４３×１０^−４
Ｅ_６＝２．０６２００×１０^−７
Ｅ_８＝−１．７２４７９×１０^−９
Ｅ_１０＝５．７２５６５×１０^−１１
非球面：第８面
Ｋ＝０．２５８０５
Ｅ_４＝−５．０４６３２×１０^−４
Ｅ_６＝−１．３７００２×１０^−５
Ｅ_８＝−５．８２０９４×１０^−７
Ｅ_１０＝−２．７５７５６×１０^−８
非球面：第１４面
Ｋ＝０
Ｅ_４＝１．９９１２１×１０^−４
Ｅ_６＝３．０４１２６×１０^−６
Ｅ_８＝−７．２２４７８×１０^−８
Ｅ_１０＝２．４７９５６×１０^−９
非球面：第１５面
Ｋ＝０．４５４６９
Ｅ_４＝−６．４３５００×１０^−５
Ｅ_６＝６．７９２５４×１０^−７
Ｅ_８＝−３．５９９９９×１０^−８
Ｅ_１０＝５．３５０７２×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔Ｄ２、第２レンズ群Ｇ２と第３レンズ群Ｇ３に一体化された絞りＦＡとの間の可変間隔Ｄ６、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔Ｄ９、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の可変間隔Ｄ１４、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の可変間隔Ｄ１６は、ズーミングに伴って次表のように変化させられる。
【００４２】
【表２】
可変間隔

【００４３】
また、この第１の実施例における先に述べた条件式（１）（請求項６の条件式）に係る（Φ_３／Φ_Ｗ）の値は、次の通りとなる。
条件式数値
（Φ_３／Φ_Ｗ）＝０．０６
したがって、この第１の実施例における先に述べた各条件式（１）に係る数値は、条件式の範囲内である。
〔第２の実施例〕
図２は、本発明の第２の実施例に係るズームレンズの光学系の構成を示している。
図２に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、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は、第１レンズ群Ｇ１を構成し、第２レンズＥ２、第３レンズＥ３および第４レンズＥ４は、第２レンズ群Ｇ２を構成し、第５レンズＥ５および第６レンズＥ６は、第３レンズ群Ｇ３を構成し、第７レンズＥ７および第８レンズＥ８は、第４レンズ群Ｇ４を構成し、そして第９レンズＥ９は、第５レンズ群Ｇ５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。上述した図１の場合と同様に、図２にも、各光学面の面番号を示しており、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。
【００４４】
図２において、ズームレンズの光学系を構成する各光学要素は、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。
第１レンズＥ１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１レンズＥ１により構成する第１レンズ群Ｇ１は、正の焦点距離を呈する。すなわち、第１レンズ群Ｇ１は、第１レンズＥ１からなる１枚の正レンズのみによって構成している。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、像面側の強い凹面を非球面とし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、これら第２レンズＥ２〜第４レンズＥ４により構成する第２レンズ群Ｇ２は、全体として負の焦点距離を呈する。すなわち、これら第２レンズＥ２、第３レンズＥ３および第４レンズＥ４は、それぞれ像面側に凹面を向けた負レンズ、像面側に非球面からなる強い凹面を向けた負レンズおよび物体側に凸面を向けた正レンズに相当する。
【００４５】
第５レンズＥ５は、物体側に強い凸面を向けた両凸レンズからなり、物体側の凸面を非球面とした正レンズ、そして第６レンズＥ６は、像面側に強い凹面を向けた両凹レンズからなる負レンズであり、これら第５レンズＥ５および第６レンズＥ６は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。これら第５レンズＥ５および第６レンズＥ６の接合レンズにより構成する第３レンズ群Ｇ３は、正の焦点距離を呈する。すなわち、この第３レンズ群Ｇ３は、非球面からなる凸面を物体側に向けた第５レンズＥ５からなる正レンズを含んでいる。第３レンズ群Ｇ３の物体側に配置された絞りＦＡは、第３レンズ群Ｇ３と一体的に動作する。第７レンズＥ７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８レンズＥ８は、物体側に強い凸面を向けた両凸レンズからなり、像面側の凸面を非球面とした正レンズであり、これら第７レンズＥ７および第８レンズＥ８は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。これら第７レンズＥ７および第８レンズＥ８の接合レンズにより構成する第４レンズ群Ｇ４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、物体側の強い凸面を非球面とした正メニスカスレンズであり、この第９レンズＥ９により構成する第５レンズ群Ｇ５は、正の焦点距離を呈する。すなわち、この第５レンズ群Ｇ５は、第９レンズＥ９からなる１枚の正レンズのみによって構成している。
【００４６】
広角端から望遠端への変倍に際しては、各群間の可変間隔、すなわち、第１レンズ群Ｇ１の最も像面側の面、つまり第１レンズＥ１の像面側の面（面番号２）と、第２レンズ群Ｇ２の最も物体側の面、つまり第２レンズＥ２の物体側の面（面番号３）との間隔Ｄ２、第２レンズ群Ｇ２の最も像面側の面、つまり第４レンズＥ４の像面側の面（面番号８）と、第３レンズ群Ｇ３に一体化された絞りＦＡの（物体側の）面（面番号９）との間隔Ｄ８、第３レンズ群Ｇ３の最も像面側の面、つまり第６レンズＥ６の像面側の面（面番号１２）と、第４レンズ群Ｇ４の最も物体側の面、つまり第７レンズＥ７の物体側の面（面番号１３）との間隔Ｄ１２、第４レンズ群Ｇ４の最も像面側の面、つまり第８レンズＥ８の像面側の面（面番号１５）と、第５レンズ群Ｇ５の最も物体側の面、つまり第９レンズＥ９の物体側の面（面番号１６）との間隔Ｄ１５および第５レンズ群Ｇ５の最も像面側の面、つまり第９レンズＥ９の像面側の面（面番号１７）と光学フィルタＯＦの物体側の面（面番号１８）との間隔Ｄ１７が変化して、第１レンズ群Ｇ１と第２レンズ群Ｇ２の間隔Ｄ２が漸次大きくなり、第２レンズ群Ｇ２と第３レンズ群Ｇ３の間隔Ｄ８が漸次小さくなり、第３レンズ群Ｇ３と第４レンズ群Ｇ４の間隔Ｄ１２が漸次小さくなり、第４レンズ群Ｇ４と第５レンズ群Ｇ５の間隔Ｄ１５が漸次大きくなり、そして第５レンズ群Ｇ５と光学フィルタＯＦの間隔Ｄ１７が漸次大きくなるように、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第３レンズ群Ｇ３、第４レンズ群Ｇ４および第５レンズ群Ｇ５が移動する。
【００４７】
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，半画角ωが、ズーミングによって、それぞれｆ＝５．８〜２３．２，Ｆ＝２．８６〜４．７３，ω＝３９．２９〜１１．０３の範囲で変化する。各光学面の特性は、次表の通りである。
【００４８】
【表３】
光学特性

【００４９】
表３に示すように第６面、第１０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（２）式におけるパラメータは、次の通りである。
非球面：第６面
Ｋ＝−１．７５７８７
Ｅ_４＝１．５８６６８×１０^−４
Ｅ_６＝−１．３１９２０×１０^−６
Ｅ_８＝１．６６２２５×１０^−９
Ｅ_１０＝−６．３５８４６×１０^−１１
非球面：第１０面
Ｋ＝０．３８７１３
Ｅ_４＝−３．４３６３１×１０^−４
Ｅ_６＝−８．４５９８２×１０^−６
Ｅ_８＝６．７１８５７×１０^−８
Ｅ_１０＝−１．７７１８８×１０^−８
非球面：第１５面
Ｋ＝０
Ｅ_４＝１．３６０８９×１０^−４
Ｅ_６＝３．７３９４８×１０^−６
Ｅ_８＝−１．３７２７８×１０^−７
Ｅ_１０＝３．２３５４４×１０^−９
非球面：第１６面
Ｋ＝０．２２７４３
Ｅ_４＝−２．８５３４２×１０^−５
Ｅ_６＝４．１０９３１×１０^−７
Ｅ_８＝−１．２６６５７×１０^−８
Ｅ_１０＝１．４１９０６×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔Ｄ２、第２レンズ群Ｇ２と第３レンズ群Ｇ３に一体化された絞りＦＡとの間の可変間隔Ｄ８、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔Ｄ１２、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の可変間隔Ｄ１５、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の可変間隔Ｄ１７は、ズーミングに伴って次表のように変化させられる。
【００５０】
【表４】
可変間隔

【００５１】
また、この第２の実施例における先に述べた条件式（１）（請求項６の条件式）に係る（Φ_３／Φ_Ｗ）の値は、次の通りとなる。
条件式数値
（Φ_３／Φ_Ｗ）＝０．０９
したがって、この第２の実施例における先に述べた各条件式（１）に係る数値は、条件式の範囲内である。
〔第３の実施例〕
図３は、本発明の第３の実施例に係るズームレンズの光学系の構成を示している。
図３に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、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は、第１レンズ群Ｇ１を構成し、第２レンズＥ２、第３レンズＥ３および第４レンズＥ４は、第２レンズ群Ｇ２を構成し、第５レンズＥ５および第６レンズＥ６は、第３レンズ群Ｇ３を構成し、第７レンズＥ７および第８レンズＥ８は、第４レンズ群Ｇ４を構成し、そして第９レンズＥ９は、第５レンズ群Ｇ５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。上述した図１および図２の場合と同様に、図３にも、各光学面の面番号を示しており、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。
【００５２】
図３において、ズームレンズの光学系を構成する各光学要素は、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。
第１レンズＥ１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１レンズＥ１により構成する第１レンズ群Ｇ１は、正の焦点距離を呈する。すなわち、第１レンズ群Ｇ１は、第１レンズＥ１からなる１枚の正レンズのみによって構成している。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、像面側に強い凹面を向けた両凹レンズからなり、像面側の凹面を非球面とした負レンズ、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、これら第２レンズＥ２〜第４レンズＥ４により構成する第２レンズ群Ｇ２は、全体として負の焦点距離を呈する。
【００５３】
すなわち、これら第２レンズＥ２、第３レンズＥ３および第４レンズＥ４は、それぞれ像面側に凹面を向けた負レンズ、像面側に非球面からなる強い凹面を向けた負レンズおよび物体側に凸面を向けた正レンズに相当する。第５レンズＥ５は、物体側に強い凸面を向けた両凸レンズからなり、物体側の凸面を非球面とした正レンズ、そして第６レンズＥ６は、像面側に強い凹面を向けた両凹レンズからなる負レンズであり、これら第５レンズＥ５および第６レンズＥ６は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。これら第５レンズＥ５および第６レンズＥ６の接合レンズにより構成する第３レンズ群Ｇ３は、正の焦点距離を呈する。すなわち、この第３レンズ群Ｇ３は、非球面からなる凸面を物体側に向けた第５レンズＥ５からなる正レンズを含んでいる。第３レンズ群Ｇ３の物体側に配置された絞りＦＡは、第３レンズ群Ｇ３と一体的に動作する。第７レンズＥ７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８レンズＥ８は、物体側に強い凸面を向けた両凸レンズからなり、像面側の凸面を非球面とした正レンズであり、これら第７レンズＥ７および第８レンズＥ８は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。
【００５４】
これら第７レンズＥ７および第８レンズＥ８の接合レンズにより構成する第４レンズ群Ｇ４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、物体側の強い凸面を非球面とした正メニスカスレンズであり、この第９レンズＥ９により構成する第５レンズ群Ｇ５は、正の焦点距離を呈する。すなわち、この第５レンズ群Ｇ５は、第９レンズＥ９からなる１枚の正レンズのみによって構成している。
広角端から望遠端への変倍に際しては、各群間の可変間隔、すなわち、第１レンズ群Ｇ１の最も像面側の面、つまり第１レンズＥ１の像面側の面（面番号２）と、第２レンズ群Ｇ２の最も物体側の面、つまり第２レンズＥ２の物体側の面（面番号３）との間隔Ｄ２、第２レンズ群Ｇ２の最も像面側の面、つまり第４レンズＥ４の像面側の面（面番号８）と、第３レンズ群Ｇ３に一体化された絞りＦＡの（物体側の）面（面番号９）との間隔Ｄ８、第３レンズ群Ｇ３の最も像面側の面、つまり第６レンズＥ６の像面側の面（面番号１２）と、第４レンズ群Ｇ４の最も物体側の面、つまり第７レンズＥ７の物体側の面（面番号１３）との間隔Ｄ１２、第４レンズ群Ｇ４の最も像面側の面、つまり第８レンズＥ８の像面側の面（面番号１５）と、第５レンズ群Ｇ５の最も物体側の面、つまり第９レンズＥ９の物体側の面（面番号１６）との間隔Ｄ１５および第５レンズ群Ｇ５の最も像面側の面、つまり第９レンズＥ９の像面側の面（面番号１７）と光学フィルタＯＦの物体側の面（面番号１８）との間隔Ｄ１７が変化して、第１レンズ群Ｇ１と第２レンズ群Ｇ２の間隔Ｄ２が漸次大きくなり、第２レンズ群Ｇ２と第３レンズ群Ｇ３の間隔Ｄ８が漸次小さくなり、第３レンズ群Ｇ３と第４レンズ群Ｇ４の間隔Ｄ１２が漸次小さくなり、第４レンズ群Ｇ４と第５レンズ群Ｇ５の間隔Ｄ１５が漸次大きくなり、そして第５レンズ群Ｇ５と光学フィルタＯＦの間隔Ｄ１７が漸次大きくなるように、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第３レンズ群Ｇ３、第４レンズ群Ｇ４および第５レンズ群Ｇ５が移動する。
【００５５】
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，半画角ωが、ズーミングによって、それぞれｆ＝５．８〜２９．０，Ｆ＝２．８９〜５．１４，ω＝３９．２７〜８．８４の範囲で変化する。各光学面の特性は、次表の通りである。
【００５６】
【表５】
光学特性

【００５７】
表５に示すように第６面、第１０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（２）式におけるパラメータは次の通りである。
【００５８】
非球面：第６面
Ｋ＝−２．５１０４９
Ｅ_４＝２．３５０４９×１０^−４
Ｅ_６＝−２．４００９７×１０^−６
Ｅ_８＝１．３１０１４×１０^−８
Ｅ_１０＝−１．０４７６６×１０^−１０
非球面：第１０面
Ｋ＝０．４５２１６
Ｅ_４＝−２．７３０６１×１０^−４
Ｅ_６＝−７．１１８４５×１０^−６
Ｅ_８＝２．３１４３１×１０^−７
Ｅ_１０＝−１．６２９０７×１０^−８
非球面：第１５面
Ｋ＝０
Ｅ_４＝２．０７４０５×１０^−４
Ｅ_６＝４．３４９３５×１０^−６
Ｅ_８＝７．９５７９３×１０^−９
Ｅ_１０＝−７．０４０２５×１０^−１０
非球面：第１６面
Ｋ＝−０．００３８０
Ｅ_４＝−１．６０５１２×１０^−５
Ｅ_６＝７．６７２０４×１０^−７
Ｅ_８＝−１．５７７８７×１０^−８
Ｅ_１０＝１．２７３９２×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔Ｄ２、第２レンズ群Ｇ２と第３レンズ群Ｇ３に一体化された絞りＦＡとの間の可変間隔Ｄ８、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔Ｄ１２、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の可変間隔Ｄ１５、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の可変間隔Ｄ１７は、ズーミングに伴って次表のように変化させられる。
【００５９】
【表６】
可変間隔

【００６０】
また、この第３の実施例における先に述べた条件式（１）（請求項６の条件式）に係る（Φ_３／Φ_Ｗ）の値は、次の通りとなる。
条件式数値
（Φ_３／Φ_Ｗ）＝０．１２
したがって、この第３の実施例における先に述べた各条件式（１）に係る数値は、条件式の範囲内である。
〔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は、第１レンズ群Ｇ１を構成し、第２レンズＥ２および第３レンズＥ３は、第２レンズ群Ｇ２を構成し、第４レンズＥ４および第５レンズＥ５は、第３レンズ群Ｇ３を構成し、第６レンズＥ６および第７レンズＥ７は、第４レンズ群Ｇ４を構成し、そして第８レンズＥ８は、第５レンズ群Ｇ５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。上述した図１〜図３の場合と同様に、図４にも、各光学面の面番号を示しており、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。
図４において、ズームレンズの光学系を構成する各光学要素は、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。
【００６１】
第１レンズＥ１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１レンズＥ１により構成する第１レンズ群Ｇ１は、正の焦点距離を呈する。すなわち、第１レンズ群Ｇ１は、第１レンズＥ１からなる１枚の正レンズのみによって構成している。第２レンズＥ２は、物体側に凸に形成され、像面側の強い凹面を非球面とし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２レンズＥ２および第３レンズＥ３により構成する第２レンズ群Ｇ２は、全体として負の焦点距離を呈する。すなわち、これら第２レンズＥ２および第３レンズＥ３は、それぞれ像面側に非球面からなる強い凹面を向けた負レンズおよび物体側に凸面を向けた正レンズに相当する。第４レンズＥ４は、物体側に強い凸面を向けた両凸レンズからなり、物体側の凸面を非球面とした正レンズ、そして第５レンズＥ５は、像面側に強い凹面を向けた両凹レンズからなる負レンズであり、これら第４レンズＥ４および第５レンズＥ５は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。これら第４レンズＥ４および第５レンズＥ５の接合レンズにより構成する第３レンズ群Ｇ３は、正の焦点距離を呈する。
【００６２】
すなわち、この第３レンズ群Ｇ３は、非球面からなる凸面を物体側に向けた第４レンズＥ４からなる正レンズを含んでいる。第３レンズ群Ｇ３の物体側に配置された絞りＦＡは、第３レンズ群Ｇ３と一体的に動作する。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、そして第７レンズＥ７は、物体側に強い凸面を向けた両凸レンズからなり、像面側の凸面を非球面とした正レンズであり、これら第６レンズＥ６および第７レンズＥ７は、密接して貼り合わせられて一体に接合され、接合レンズを形成している。これら第６レンズＥ６および第７レンズＥ７の接合レンズにより構成する第４レンズ群Ｇ４は、全体として正の焦点距離を呈する。
【００６３】
第８レンズＥ８は、物体側に凸に形成され、物体側の強い凸面を非球面とした正メニスカスレンズであり、この第８レンズＥ８により構成する第５レンズ群Ｇ５は、正の焦点距離を呈する。すなわち、この第５レンズ群Ｇ５は、第８レンズＥ８からなる１枚の正レンズのみによって構成している。
広角端から望遠端への変倍に際しては、各群間の可変間隔、すなわち、第１レンズ群Ｇ１の最も像面側の面、つまり第１レンズＥ１の像面側の面（面番号２）と、第２レンズ群Ｇ２の最も物体側の面、つまり第２レンズＥ２の物体側の面（面番号３）との間隔Ｄ２、第２レンズ群Ｇ２の最も像面側の面、つまり第３レンズＥ３の像面側の面（面番号６）と、第３レンズ群Ｇ３に一体化された絞りＦＡの（物体側の）面（面番号７）との間隔Ｄ６、第３レンズ群Ｇ３の最も像面側の面、つまり第５レンズＥ５の像面側の面（面番号１０）と、第４レンズ群Ｇ４の最も物体側の面、つまり第６レンズＥ６の物体側の面（面番号１１）との間隔Ｄ１０、第４レンズ群Ｇ４の最も像面側の面、つまり第７レンズＥ７の像面側の面（面番号１３）と、第５レンズ群Ｇ５の最も物体側の面、つまり第８レンズＥ８の物体側の面（面番号１４）との間隔Ｄ１３および第５レンズ群Ｇ５の最も像面側の面、つまり第８レンズＥ８の像面側の面（面番号１５）と光学フィルタＯＦの物体側の面（面番号１６）との間隔Ｄ１５が変化して、第１レンズ群Ｇ１と第２レンズ群Ｇ２の間隔Ｄ２が漸次大きくなり、第２レンズ群Ｇ２と第３レンズ群Ｇ３の間隔Ｄ６が漸次小さくなり、第３レンズ群Ｇ３と第４レンズ群Ｇ４の間隔Ｄ１０が一旦大きくなってから小さくなり、第４レンズ群Ｇ４と第５レンズ群Ｇ５の間隔Ｄ１３が漸次大きくなり、そして第５レンズ群Ｇ５と光学フィルタＯＦの間隔Ｄ１５が一旦大きくなってから小さくなるように、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第３レンズ群Ｇ３、第４レンズ群Ｇ４および第５レンズ群Ｇ５が移動する。
【００６４】
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，半画角ωが、ズーミングによって、それぞれｆ＝７．３２〜２９．０，Ｆ＝３．３５〜５．１５，ω＝３１．４７〜８．８３の範囲で変化する。各光学面の特性は、次表の通りである。
【００６５】
【表７】
光学特性

【００６６】
表７に示すように第４面、第８面、第１３面および第１４面の各光学面が非球面であり、各非球面の（２）式におけるパラメータは次の通りである。
【００６７】
非球面：第４面
Ｋ＝−１．１２９５６
Ｅ_４＝３．１６８９２×１０^−４
Ｅ_６＝２．４９２０２×１０^−６
Ｅ_８＝−３．７７１８０×１０^−８
Ｅ_１０＝３．７１３５９×１０^−１０
非球面：第８面
Ｋ＝０．３０９１１
Ｅ_４＝−３．３９８８７×１０^−４
Ｅ_６＝−９．２３０７０×１０^−６
Ｅ_８＝１．４８５３２×１０^−７
Ｅ_１０＝−１．８２１９０×１０^−８
非球面：第１３面
Ｋ＝０
Ｅ_４＝−８．８７２２８×１０^−５
Ｅ_６＝−３．３１７４９×１０^−７
Ｅ_８＝６．２４６６７×１０^−８
Ｅ_１０＝−１．０１９０３×１０^−８
非球面：第１４面
Ｋ＝０．０１７９８
Ｅ_４＝−４．５６１２５×１０^−５
Ｅ_６＝１．６７９０１×１０^−７
Ｅ_８＝５．１４６７０×１０^−９
Ｅ_１０＝−１．３０２５９×１０^−１０
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の可変間隔Ｄ２、第２レンズ群Ｇ２と第３レンズ群Ｇ３に一体化された絞りＦＡとの間の可変間隔Ｄ６、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の可変間隔Ｄ１０、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の可変間隔Ｄ１３、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の可変間隔Ｄ１５は、ズーミングに伴って次表のように変化させられる。
【００６８】
【表８】
可変間隔

【００６９】
また、この第４の実施例における先に述べた条件式（１）（請求項６の条件式）に係る（Φ_３／Φ_Ｗ）の値は、次の通りとなる。
【００７０】
条件式数値
（Φ_３／Φ_Ｗ）＝０．２２
したがって、この第４の実施例における先に述べた各条件式（１）に係る数値は、条件式の範囲内である。
図５〜図７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、非点収差および歪曲収差の収差曲線図を示しており、このうち、図５は、広角端における収差曲線図、図６は、中間焦点距離における収差曲線図、そして図７は、望遠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。
【００７１】
図８〜図１０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、非点収差および歪曲収差の収差曲線図を示しており、図８は、広角端における収差曲線図、図９は、中間焦点距離における収差曲線図、そして図１０は、望遠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１１〜図１３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、非点収差および歪曲収差の収差曲線図を示しており、図１１は、広角端における収差曲線図、図１２は、中間焦点距離における収差曲線図、そして図１３は、望遠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、そして太線はｄ線、細線はｇ線をあらわしている。
【００７２】
そして、図１４〜図１６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、非点収差および歪曲収差の収差曲線図を示しており、図１４は、広角端における収差曲線図、図１５は、中間焦点距離における収差曲線図、そして図１６は、望遠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５〜図１６の収差曲線図によれば、上述した本発明の第１〜第４の実施例に係る図１〜図４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。
次に、上述した第１〜第４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構成したカメラの一つの実施の形態について図１７〜図１９を参照して説明する。図１７（ａ）、（ｂ）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１８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１９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。
【００７３】
図１７および図１８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１９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４の実施例において説明したような本発明に係るズームレンズを用いる。
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。
【００７４】
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。
撮影レンズ１０１は、カメラの携帯時には図１７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１７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、例えば広角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、望遠端と広角端との間の任意の変倍動作を行うことができる。なお、望ましくは、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。本発明に係る正−負−正−正−正の５群で構成されるズームレンズ（請求項１〜請求１５で定義され、あるいは第１〜第４の実施例に示されたズームレンズ）におけるフォーカシングは、第５レンズ群Ｇ５の移動、全系の移動、あるいは、受光素子２０１の移動などによって行うことができるが、単レンズによって小型で且つ軽量に構成することが可能な第５レンズ群Ｇ５の移動による方式を採用すれば、高速に且つ簡易にフォーカシングを行なうことができる。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。
【００７５】
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４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〜５００万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。この場合、携帯情報端末装置では、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。
また、この種のズームレンズは、カメラ等における撮影用光学系だけでなく、プロジェクタにおける投影光学系にも好適であり、上述した第１〜第４の実施例に示された（あるいは請求項１〜請求１５で定義された）ズームレンズを投影用光学系として用いて構成したプロジェクタとして本発明を実施してもよい。
【００７６】
【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、正の屈折力を有する第１レンズ群と、負の屈折力を有する第２レンズ群と、正の屈折力を有する第３レンズ群と、正の屈折力を有する第４レンズ群と、正の屈折力を有する第５レンズ群とを配置してなる正−負−正−正−正の５群以上の構成を用いるズームレンズにおいて、充分に広画角からの高変倍比を達成しながら、小型で且つ明るく、しかも３００万〜５００万画素の撮像素子に対応する高い解像力を、少ないレンズ構成枚数で、低コストに得ることを可能とするズームレンズ、カメラ、携帯情報端末装置およびプロジェクタを提供することができる。
特に、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、正の屈折力を有する第１レンズ群と、負の屈折力を有する第２レンズ群と、正の屈折力を有する第３レンズ群と、正の屈折力を有する第４レンズ群と、正の屈折力を有する第５レンズ群とを配置してなるズームレンズにおいて、少なくとも前記第２レンズ群、第３レンズ群および第４レンズ群を移動することによって変倍動作を行なうとともに、前記第２レンズ群は、非球面を形成してなる強い凹面を像面側に向けた負レンズを含むことにより、充分に広画角からの高変倍比を達成しながら、小型で且つ明るく、しかも３００万〜５００万画素の撮像素子に対応する高い解像力を、少ないレンズ構成枚数で、低コストに得るとともに、広角側での歪曲収差、像面湾曲および非点収差を効率良く補正することが可能となる。
【００７７】
また、本発明の請求項２のズームレンズによれば、物体側から、順次、正の屈折力を有する第１レンズ群と、負の屈折力を有する第２レンズ群と、正の屈折力を有する第３レンズ群と、正の屈折力を有する第４レンズ群と、正の屈折力を有する第５レンズ群とを配置してなるズームレンズにおいて、広角端から望遠端への変倍時に、第１レンズ群と第２レンズ群の間隔が大きくなり、第２レンズ群と第３レンズ群の間隔が小さくなり、第３レンズ群と第４レンズ群の間隔が小さくなるように、少なくとも第２レンズ群、第３レンズ群および第４レンズ群を移動することによって変倍動作を行なうとともに、前記第２レンズ群は、非球面を形成してなる強い凹面を像面側に向けた負レンズを含むことにより、充分に広画角からの高変倍比を達成しながら、小型で、明るく、且つ高い解像力を、特に、少ないレンズ構成枚数で、低コストに得ることを可能として、しかも広角側での歪曲収差、像面湾曲および非点収差を効率良く補正することが可能となる。
【００７８】
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のズームレンズであって、前記第１レンズ群が、１枚の正レンズからなることにより、特に、少ないレンズ構成枚数とすることができて、さらなる小型化が可能となる。本発明の請求項４のズームレンズによれば、請求項１または請求項２のズームレンズであって、前記第２レンズ群が、物体側から、順次、像面側に強い凹面を向けた負レンズと、物体側に凸面を向けた正レンズとを配置することにより、特に、３〜４程度の変倍比を達成するレンズ構成をより簡単化することができる。本発明の請求項５のズームレンズによれば、請求項１または請求項２のズームレンズであって、前記第２レンズ群が、物体側から、順次、像面側に凹面を向けた負レンズと、負レンズと、物体側に凸面を向けた正レンズとを配置することにより、特に、４を超える変倍比を達成するレンズ構成をより効率良く構成することができる。
【００７９】
本発明の請求項６のズームレンズによれば、請求項１または請求項２のズームレンズであって、前記第３レンズ群が、当該第３レンズ群の屈折力をΦ_３とし、そして全系の屈折力をΦ_Ｗとして、
条件式：
０．０５＜Φ_３／Φ_Ｗ＜１．０
を満足することにより、特に、第２レンズ群から入射される発散光束の球面収差を効率良く補正することが可能となる。
本発明の請求項７のズームレンズによれば、請求項６のズームレンズであって、前記第３レンズ群が、変倍時に、絞りと一体に移動することにより、特に、収差補正を行なう光束を効果的に制限して、より効率良く収差補正を行うことが可能となる。
本発明の請求項８のズームレンズによれば、請求項７のズームレンズであって、前記第３レンズ群が、非球面を形成してなる凸面を物体側に向けた正レンズを含むことにより、特に、絞りによって制限された光束の球面収差を効率良く補正することが可能となる。
【００８０】
本発明の請求項９のズームレンズによれば、請求項１または請求項２のズームレンズであって、前記第５レンズ群が、１枚の正レンズからなることにより、特に、結像面の電子的撮像素子に入射する光線を平行光とし且つ全体の収差を整える第５レンズ群を少ない枚数で構成して軽量化を図り、この第５レンズ群による合焦速度も向上させることができる。
本発明の請求項１０のズームレンズによれば、請求項９のズームレンズであって、前記第５レンズ群が、少なくとも１面の非球面を含むことにより、特に、結像面の電子的撮像素子に入射する光線を平行光とし且つ全体の収差を整える第５レンズ群の軽量化により、第５レンズ群による合焦速度も向上させて、しかも収差補正の自由度を上げて、無限遠から近距離まで、良好な撮影性能を得ることが可能となる。
本発明の請求項１１のズームレンズによれば、請求項１または請求項２のズームレンズであって、前記第５レンズ群を移動することによって、有限遠物体への合焦動作を行なうことにより、特に、合焦動作を簡易にしかも高速に行なうことが可能となる。
【００８１】
本発明の請求項１２のカメラによれば、撮影用光学系として、請求項１〜請求項１１のいずれか１項のズームレンズを含むことにより、特に、充分に広画角からの高変倍比を達成しながら、小型で且つ明るく、しかも、広角側での歪曲収差、像面湾曲および非点収差を効率良く補正して、３００万〜５００万画素の撮像素子に対応する高い解像力の撮影を、少ないレンズ構成枚数で且つ低コストで実現することが可能となる。
本発明の請求項１３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１１のいずれか１項のズームレンズを含むことにより、特に、充分に広画角からの高変倍比を達成しながら、小型で且つ明るく、しかも、広角側での歪曲収差、像面湾曲および非点収差を効率良く補正して、３００万〜５００万画素の撮像素子に対応する高い解像力の撮影を、少ないレンズ構成枚数で且つ低コストで実現することが可能となる。
本発明の請求項１４のプロジェクタによれば、投影用光学系として、請求項１〜請求項１１のいずれか１項のズームレンズを含むことにより、特に、充分に広画角からの高変倍比を達成しながら、小型で且つ明るく、しかも、広角側での歪曲収差、像面湾曲および非点収差を効率良く補正して、高い解像力の投影を、少ないレンズ構成枚数で且つ低コストで実現することが可能となる。
【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である。
【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である。
【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である。
【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である。
【図５】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広角端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図６】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、非点収差および歪曲収差を示す収差曲線図である。
【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望遠端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図８】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広角端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図９】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、非点収差および歪曲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望遠端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図１１】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広角端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図１２】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、非点収差および歪曲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望遠端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図１４】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広角端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図１５】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、非点収差および歪曲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望遠端における球面収差、非点収差および歪曲収差を示す収差曲線図である。
【図１７】本発明に係るカメラの一つの実施の形態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、このうち、
（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１８】図１７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１９】図１７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レンズ群
Ｇ２ 第２レンズ群
Ｇ３ 第３レンズ群
Ｇ４ 第４レンズ群
Ｇ５ 第５レンズ群
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]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a zoom lens in which a plurality of lens groups are individually advanced and retracted in the optical axis direction to set different focal lengths including a wide angle region, and in particular, like a digital camera and a video camera. The present invention relates to a zoom lens suitable for a camera using an electronic imaging means, and a camera, a portable information terminal device, and a projector using such a zoom lens.
[0002]
[Prior art]
It is called a digital camera or an electronic camera, and a subject image is picked up by a solid-state image pickup device such as a CCD (charge coupled device) image pickup device, and image data of a still image (still image) or a moving image (movie image) of the subject. The type of camera that records digitally in a non-volatile semiconductor memory such as a flash memory has already been generalized, and the conventional camera using a conventional silver salt film, that is, a silver salt camera is Is no longer the thing of the past.
The market for such digital cameras has become very large, and user demands for digital cameras have also varied. Above all, high image quality and miniaturization are always what users want.
In recent years, a 3 × zoom lens with a wide-angle end angle of view of about 62 degrees has been the mainstream as a photographic lens used in a lens-integrated digital camera. This is because the front lens diameter and total lens length of the photographing lens can be made compact by suppressing the angle of view and the zoom ratio to this extent. However, since the photographic lens that is normally used in the photographic lens for a silver salt camera is a zoom lens having a zoom ratio of about 3 to 5 times from a wide-angle end angle of view of about 74 degrees, A wide-angle field of view and high zoom ratio, which is equivalent to or better than that of a silver halide camera, is also used for camera lenses. There is a demand for a zoom lens capable of obtaining a corresponding high resolution.
[0003]
A positive-negative-positive-positive-positive 5-group zoom lens suitable for a zoom lens having a wide angle of view and a high zoom ratio, that is, a first lens group having a positive refractive power, a first lens group having a negative refractive power. Five lens groups of two lens groups, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power are sequentially arranged from the object side. Conventionally, there are various proposals for a zoom lens. In the past, zoom lenses having a zoom ratio of about 3 times from the angle of view of about 64 degrees at the wide angle end have been proposed (for example, Patent Document 1 below). In addition, a zoom lens having a zoom ratio of 11 times or more from a field angle of about 70 degrees at the wide angle end (for example, Patent Document 2 below), or a zoom ratio of about 10 times from a field angle of about 74 degrees at the wide angle end. A zoom lens having a ratio (for example, Patent Document 3, Patent Document 4, and Patent Document 5 below) has also been proposed.
[0004]
[Patent Document 1]
JP-A-57-195213
[Patent Document 2]
Japanese Patent No. 3352804
[Patent Document 3]
Japanese Patent Laid-Open No. 10-161028
[Patent Document 4]
JP 2002-98893 A
[Patent Document 5]
JP 2002-156581 A
[0005]
[Problems to be solved by the invention]
However, the zoom lens disclosed in Patent Document 1 has as many as 18 or more lenses, and only covers a zoom ratio of about 3 times from an angle of view of about 64 degrees at the wide angle end. It was. In the zoom lens disclosed in Patent Document 2, the first lens group, the third lens group, and the fifth lens group are fixed at the time of zooming. It is difficult to achieve the resolving power corresponding to an image sensor with 3 to 5 million pixels with the configuration and refractive power arrangement disclosed here.
Furthermore, although the zoom lens disclosed in Patent Document 3 has a zoom ratio of 10 times or more from an angle of view of about 74 degrees at the wide angle end, the brightness of the lens is F number (F value). It is dark as 4.1 or less. The zoom lens disclosed in Patent Document 4 has almost no change in the distance between the third lens group and the fourth lens group at the time of zooming, and is much different from the configuration of four groups of positive-negative-positive-positive. Therefore, the advantages of the five groups of positive-negative-positive-positive-positive are not fully utilized. Further, the zoom lens disclosed in Patent Document 5 relating to the application of the present applicant has a zoom ratio of about 5 times from an angle of view of about 64 degrees at the wide angle end, and the number of lenses is about 10. Although there are few, there is still room for widening the angle of view.
[0006]
The present invention has been made in view of the circumstances described above, and in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. A configuration of five or more positive-negative-positive-positive-positive five groups in which a third lens group having a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power are arranged. In a zoom lens using a zoom lens, while achieving a high zoom ratio from a wide angle of view, it is small and bright, and has a high resolving power corresponding to an image sensor with 3 to 5 million pixels with a small number of lens components. An object of the present invention is to provide a zoom lens, a camera, a portable information terminal device, and a projector that can be obtained at low cost.
That is, an object of claim 1 of the present invention is to achieve a high resolution corresponding to an image pickup device of 3 to 5 million pixels while being small and bright while sufficiently achieving a high zoom ratio from a wide angle of view. An object of the present invention is to provide a zoom lens that can be obtained at a low cost with a small number of lenses, and that can efficiently correct distortion, curvature of field and astigmatism on the wide-angle side.
Further, the second aspect of the present invention is to obtain a small, bright, and high resolving power at a low cost with a small number of lenses, while achieving a sufficiently high zoom ratio from a wide angle of view. It is another object of the present invention to provide a zoom lens that can efficiently correct distortion, field curvature, and astigmatism on the wide-angle side.
[0007]
A third object of the present invention is to provide a zoom lens that can reduce the number of lenses, and can be further reduced in size.
A fourth object of the present invention is to provide a zoom lens that can simplify the lens configuration that achieves a zoom ratio of about 3 to 4, in particular.
An object of claim 5 of the present invention is to provide a zoom lens that can more efficiently construct a lens configuration that achieves a zoom ratio of more than 4.
An object of claim 6 of the present invention is to provide a zoom lens that can efficiently correct the spherical aberration of the divergent light beam incident from the second lens group.
An object of claim 7 of the present invention is to provide a zoom lens that can effectively perform aberration correction more effectively by effectively limiting a light beam for performing aberration correction.
An object of an eighth aspect of the present invention is to provide a zoom lens that can efficiently correct spherical aberration of a light beam limited by a diaphragm.
[0008]
The object of claim 9 of the present invention is to reduce the weight by forming a small number of the fifth lens group that makes the light incident on the electronic image pickup device of the imaging plane parallel light and adjusts the overall aberration, An object of the present invention is to provide a zoom lens capable of improving the focusing speed by the fifth lens group.
The object of claim 10 of the present invention is to focus on the fifth lens group by reducing the weight of the fifth lens group, which makes the light incident on the electronic imaging device on the imaging plane parallel light and adjusts the overall aberration. An object of the present invention is to provide a zoom lens capable of improving the speed and increasing the degree of freedom of aberration correction and obtaining good photographing performance from infinity to a short distance.
The object of the eleventh aspect of the present invention is to provide a zoom lens that can perform the focusing operation easily and at high speed.
The object of the twelfth aspect of the present invention is particularly small and bright while sufficiently achieving a high zoom ratio from a wide angle of view, and further, distortion on the wide angle side, field curvature and astigmatism. It is an object of the present invention to provide a camera that can efficiently correct aberrations and realize high-resolution imaging corresponding to an image sensor with 3 to 5 million pixels with a small number of lenses and at low cost.
[0009]
The object of the thirteenth aspect of the present invention is to reduce distortion and field curvature and astigmatism on the wide-angle side, in particular, while achieving a high zoom ratio from a wide angle of view. An object of the present invention is to provide a portable information terminal device capable of efficiently correcting and realizing high-resolution imaging corresponding to an imaging element with 3 to 5 million pixels with a small number of lenses and at a low cost. .
The object of the fourteenth aspect of the present invention is to reduce distortion and field curvature and astigmatism on the wide-angle side, in particular, while achieving a high zoom ratio from a sufficiently wide angle of view. An object of the present invention is to provide a projector capable of efficiently correcting and realizing a high resolution projection with a small number of lens components and at a low cost.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a zoom lens according to the present invention described in claim 1 is provided.
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. In a zoom lens comprising a lens group and a fifth lens group having a positive refractive power,
A zooming operation is performed by moving at least the second lens group, the third lens group, and the fourth lens group, and
The second lens group includes a negative lens having a strong concave surface formed with an aspherical surface directed toward the image plane side.
[0011]
In order to achieve the above object, a zoom lens according to the present invention described in claim 2 is provided.
In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. In a zoom lens comprising a lens group and a fifth lens group having a positive refractive power,
At the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the third lens group and the fourth lens group. The zooming operation is performed by moving at least the second lens group, the third lens group, and the fourth lens group so that the interval of
The second lens group includes a negative lens having a strong concave surface formed with an aspherical surface directed toward the image plane side.
A zoom lens according to a third aspect of the present invention is the zoom lens according to the first or second aspect, wherein the first lens group is composed of one positive lens.
[0012]
A zoom lens according to the present invention described in claim 4 is the zoom lens according to claim 1 or 2,
The second lens group sequentially from the object side,
A negative lens with a strong concave surface on the image side,
A positive lens having a convex surface facing the object side is arranged.
The zoom lens according to the present invention described in claim 5 is the zoom lens according to claim 1 or 2,
The second lens group sequentially from the object side,
A negative lens with a concave surface facing the image surface,
A negative lens,
A positive lens having a convex surface facing the object side is arranged.
[0013]
A zoom lens according to the present invention described in claim 6 is the zoom lens according to claim 1 or 2,
The third lens group is
The refractive power of the third lens group is Φ₃And the refractive power of the entire system is Φ_WAs
Conditional expression:
0.05 <Φ₃/ Φ_W<1.0
It is characterized by satisfying.
A zoom lens according to a seventh aspect of the present invention is the zoom lens according to the sixth aspect, wherein the third lens group moves integrally with the stop during zooming.
The zoom lens according to an eighth aspect of the present invention is the zoom lens according to the seventh aspect, wherein the third lens group includes a positive lens having a convex surface formed with an aspherical surface directed toward the object side. It is characterized by.
A zoom lens according to a ninth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the fifth lens group includes one positive lens.
[0014]
A zoom lens according to a tenth aspect of the present invention is the zoom lens according to the ninth aspect, wherein the fifth lens group includes at least one aspherical surface.
The zoom lens according to the present invention described in claim 11 is the zoom lens according to claim 1 or 2, wherein the zoom lens performs a focusing operation on a finite distance object by moving the fifth lens group. It is characterized by.
A camera according to a twelfth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system.
A portable information terminal device according to a thirteenth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system of a camera function unit.
A projector according to a fourteenth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects as a projection optical system.
[0015]
[Action]
In other words, the zoom lens according to the first aspect of the present invention, in order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the first lens group having a positive refractive power. In a zoom lens including three lens groups, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, at least the second lens group, the third lens group, and the first lens group The second lens group includes a negative lens in which a strong concave surface that forms an aspheric surface is directed to the image plane side while performing a zooming operation by moving the four lens groups.
With such a configuration, while achieving a high zoom ratio from a sufficiently wide angle of view, a small and bright, high resolution corresponding to an image sensor with 3 to 5 million pixels with a small number of lens components, It is possible to obtain low cost and to efficiently correct distortion, curvature of field and astigmatism on the wide angle side.
[0016]
In the zoom lens according to claim 2 of the present invention, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a first lens group having a positive refractive power. In a zoom lens in which three lens groups, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power are arranged, the first lens is changed upon zooming from the wide-angle end to the telephoto end. At least the second lens group so that the distance between the lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the distance between the third lens group and the fourth lens group is decreased. The second lens group includes a negative lens in which a strong concave surface that forms an aspherical surface is directed to the image plane side while performing a zooming operation by moving the third lens group and the fourth lens group. Yes.
With such a configuration, while achieving a high zoom ratio from a sufficiently wide angle of view, it is possible to obtain a small size, brightness, and high resolving power, particularly with a small number of lens components, at a low cost. It becomes possible to efficiently correct distortion, field curvature, and astigmatism on the wide angle side.
[0017]
A zoom lens according to a third aspect of the present invention is the zoom lens according to the first or second aspect, wherein the first lens group is composed of one positive lens.
With such a configuration, in particular, the number of lens components can be reduced, and further miniaturization is possible.
A zoom lens according to a fourth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the second lens group includes a negative lens having a strong concave surface directed sequentially from the object side to the image plane side. A positive lens having a convex surface facing the object side is disposed.
With such a configuration, in particular, a lens configuration that achieves a zoom ratio of about 3 to 4 can be further simplified.
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the second lens group includes a negative lens having a concave surface directed sequentially from the object side to the image plane side, A negative lens and a positive lens having a convex surface facing the object side are arranged.
With such a configuration, in particular, a lens configuration that achieves a zoom ratio exceeding 4 can be configured more efficiently.
[0018]
A zoom lens according to a sixth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the third lens group has a refractive power of Φ of the third lens group.₃And the refractive power of the entire system is Φ_WAs
Conditional expression:
0.05 <Φ₃/ Φ_W<1.0
Satisfied.
With such a configuration, in particular, it is possible to efficiently correct the spherical aberration of the divergent light beam incident from the second lens group.
A zoom lens according to a seventh aspect of the present invention is the zoom lens according to the sixth aspect, wherein the third lens group moves integrally with the stop during zooming.
With such a configuration, in particular, it is possible to effectively limit the light flux for aberration correction and perform aberration correction more efficiently.
A zoom lens according to an eighth aspect of the present invention is the zoom lens according to the seventh aspect, wherein the third lens group includes a positive lens having a convex surface formed with an aspherical surface directed toward the object side.
With such a configuration, in particular, it is possible to efficiently correct the spherical aberration of the light beam limited by the stop.
[0019]
A zoom lens according to a ninth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the fifth lens group is composed of one positive lens.
With such a configuration, in particular, the fifth lens group that makes the light incident on the electronic image pickup device on the imaging plane parallel light and adjusts the overall aberration is configured with a small number of lenses to reduce the weight. The focusing speed by the group can also be improved.
A zoom lens according to a tenth aspect of the present invention is the zoom lens according to the ninth aspect, wherein the fifth lens group includes at least one aspherical surface.
With such a configuration, in particular, the focusing speed of the fifth lens group can be improved by reducing the weight of the fifth lens group that makes the light incident on the electronic imaging device on the imaging plane parallel light and adjusts the overall aberration. In addition, it is possible to increase the degree of freedom of aberration correction and to obtain good photographing performance from infinity to a short distance.
A zoom lens according to an eleventh aspect of the present invention is the zoom lens according to the first or second aspect, and performs a focusing operation on a finite distance object by moving the fifth lens group.
With such a configuration, in particular, the focusing operation can be performed easily and at high speed.
[0020]
A camera according to a twelfth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system.
With such a configuration, in particular, while achieving a high zoom ratio from a wide angle of view, it is compact and bright, and efficiently corrects distortion, curvature of field and astigmatism on the wide angle side. Therefore, it is possible to realize high-resolution imaging corresponding to an image sensor with 3 to 5 million pixels with a small number of lenses and at low cost.
A portable information terminal device according to a thirteenth aspect of the present invention includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system of a camera function unit.
With such a configuration, in particular, while achieving a high zoom ratio from a wide angle of view, it is compact and bright, and efficiently corrects distortion, curvature of field and astigmatism on the wide angle side. Therefore, it is possible to realize high-resolution imaging corresponding to an image sensor with 3 to 5 million pixels with a small number of lenses and at low cost.
[0021]
A projector according to claim 14 of the present invention includes the zoom lens according to any one of claims 1 to 11 as a projection optical system.
With such a configuration, in particular, while achieving a high zoom ratio from a wide angle of view, it is compact and bright, and efficiently corrects distortion, curvature of field and astigmatism on the wide angle side. Thus, high resolution projection can be realized with a small number of lenses and at a low cost.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, based on an embodiment of the present invention, a zoom lens, a camera, a portable information terminal device, and a projector according to the present invention will be described in detail with reference to the drawings. Before describing specific examples, first, in order to explain the principle embodiments of the present invention, configurations and functions defined in the claims of the claims will be described.
The zoom lens according to claims 1 to 11 of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a positive lens The fourth lens group having a refractive power of 5 and the fifth lens group having a positive refractive power are sequentially arranged from the object side, and each has the following characteristics.
The zoom lens according to claim 1 performs a zooming operation by moving at least the second lens group, the third lens group, and the fourth lens group, and the second lens group is strong on the image plane side. A negative lens having a concave surface is included, and the concave surface is formed as an aspherical surface.
[0023]
In the zoom lens according to claim 2, when zooming from the wide-angle end to the telephoto end, an interval between the first lens group and the second lens group is gradually increased, and an interval between the second lens group and the third lens group is increased. Is changed by moving at least the second lens group, the third lens group, and the fourth lens group so that the distance between the third lens group and the fourth lens group becomes gradually smaller. The second lens group includes a negative lens having a strong concave surface facing the image surface side, and the concave surface is formed as an aspherical surface.
A zoom lens according to a third aspect is the zoom lens according to the first or second aspect, wherein the first lens group is composed of one positive lens.
The zoom lens according to claim 4 is the zoom lens according to claim 1 or 2, wherein the second lens group includes a negative lens having a strong concave surface on the image surface side and a positive lens having a convex surface on the object side. It consists of and.
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to the first or second aspect, wherein the second lens group has a negative lens with a concave surface facing the image plane side, a negative lens, and a convex surface facing the object side. And a positive lens.
[0024]
The zoom lens according to a sixth aspect is the zoom lens according to the first or second aspect, wherein the third lens group satisfies the following conditional expression.
[0025]
0.05 <Φ₃/ Φ_W<1.0 (1)
However, Φ₃Indicates the refractive power of the third lens group, and Φ_WIndicates the refractive power of the entire system.
A zoom lens according to a seventh aspect is the zoom lens according to the sixth aspect, wherein the third lens group is moved integrally with the stop during zooming.
In a zoom lens according to an eighth aspect, in the zoom lens according to the seventh aspect, the third lens group includes a positive lens having a convex surface facing the object side, and the convex surface is formed as an aspherical surface.
A zoom lens according to a ninth aspect is the zoom lens according to the first or second aspect, wherein the fifth lens group is composed of one positive lens.
A zoom lens according to a tenth aspect is the zoom lens according to the ninth aspect, wherein the fifth lens group includes at least one aspherical surface.
A zoom lens according to an eleventh aspect is the zoom lens according to the first or second aspect, wherein the fifth lens group is moved to focus on a finite object.
[0026]
A camera according to a twelfth aspect includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system.
A portable information terminal device according to a thirteenth aspect includes the zoom lens according to any one of the first to eleventh aspects as a photographing optical system of a camera function unit.
A projector according to a fourteenth aspect uses the zoom lens according to any one of the first to eleventh aspects as a projection optical system.
Next, the embodiments defined in the claims of the above-described claims of the present invention will be described in more detail.
The zoom lens according to the present invention has a positive-negative-positive-positive-positive-5-group configuration, that is, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power. And a third lens group having a positive refractive power, and a fifth lens group having a positive refractive power are sequentially arranged from the object side. At the time of zooming to the telephoto end, zooming operation is performed by individually advancing and retracting at least the second lens group, the third lens group, and the fourth lens group (corresponding to claims 1 and 2). .
[0027]
The movement of each lens group accompanying the zooming operation is specifically, specifically, for example, where the distance between the first lens group and the second lens group is gradually increased, and the distance between the second lens group and the third lens group. Is gradually reduced and the distance between the third lens group and the fourth lens group is gradually reduced (corresponding to claim 2). The zoom lens includes a negative lens having a strong concave surface facing the image plane side in the second lens group, and the concave surface is an aspherical surface (corresponding to claims 1 and 2). Thus, it is possible to efficiently correct distortion, curvature of field, and astigmatism on the wide angle side. That is, correction of various aberrations such as distortion, curvature of field and astigmatism is made by manipulating the surface through which the principal ray of the light beam incident from outside the optical axis passes greatly away from the optical axis. It is desirable that the concave surface having the strongest curvature among the target surfaces is aspherical, so that the light beam path can be effectively manipulated.
By using an aspherical surface in this way, a zoom lens having a zoom ratio of about 2 to 6 times from the wide-angle end of the wide field angle range with a lens configuration of five groups of positive-negative-positive-positive-positive. The first lens group, which normally requires three lenses, can be simply configured with one lens, and the entire zoom lens can be reduced in size (corresponding to claim 3). .
[0028]
However, when the zoom ratio exceeds 6, it is desirable to increase the number of constituent lenses of the first lens group in order to correct spherical aberration at the telephoto end. When the zoom ratio is about 3 to 4 times, the second lens group is composed of two lenses, a negative lens having a strong concave surface on the image side and a positive lens having a convex surface on the object side. Are arranged sequentially (corresponding to claim 4), and when the zoom ratio exceeds 4 times, the second lens group includes a negative lens having a concave surface facing the image plane side, a negative lens, In addition, it is desirable that the positive lens with the convex surface facing the object side is sequentially arranged from the object side (corresponding to claim 5). With this configuration, it is possible to easily achieve downsizing as compared with the second lens group in which strong concave surfaces face each other as used in the zoom lens described in Patent Document 4. As described above, when the second lens group is composed of three lenses, that is, a negative lens having a concave surface facing the image surface, a negative lens, and a positive lens having a convex surface facing the object side, The negative lens may be aspherical.
[0029]
In the configuration according to the present invention, the third lens group, the fourth lens group, and the fifth lens group mainly serve as an imaging system, while changing the mutual distance, It also plays a role in correcting various aberrations including field curvature. In order to efficiently correct the spherical aberration of the divergent light beam incident from the second lens group, the conditional expression:
0.05 <Φ₃/ Φ_W<1.0 (1)
Is preferably satisfied (corresponding to claim 6). Φ₃/ Φ_WHowever, if it exceeds 1.0, the divergent light beam is incident on the fourth lens group with almost no refracting action, so the lens outer diameter of the fourth lens group inevitably increases, and aberration correction is performed. This is not desirable because it becomes difficult. Φ₃/ Φ_WHowever, if it is less than 0.05, the refractive power of the third lens group becomes too strong, which is undesirable from the viewpoints of aberration correction and increased decentration sensitivity. Further, in order to perform aberration correction more efficiently, it is possible to limit the luminous flux for which aberration correction is performed by arranging a stop before and after the third lens group, or by moving the third lens group and the stop together. Desirable (corresponding to claim 7). In this case, preferably, the spherical aberration of the limited light beam can be corrected efficiently by using an aspherical surface with a convex surface facing the object side (corresponding to claim 8).
[0030]
Further, desirably, chromatic aberration correction and higher-order aberration correction can be performed by disposing at least one cemented lens in the third lens group or in the fourth lens group. In the zoom lens according to the present invention, an electronic image pickup device is mainly arranged on the imaging plane to form an imaging target. Therefore, it is desirable that the light incident on the imaging plane is parallel light. By arranging the fifth lens group having a positive refractive power in the vicinity of the image forming surface, this condition can be easily achieved, and the fifth lens group also plays a role of adjusting the entire aberration. Such a fifth lens group is preferably composed of a single positive lens (corresponding to claim 9), for example, by constituting a small number of lenses to reduce the weight and using it as a focus group. (Corresponding to claim 11), the focusing speed can be improved. At this time, more preferably, by using at least one aspherical surface for this focusing group (corresponding to claim 10), in order to obtain good photographing performance with a small number of lenses from infinity to a short distance, The degree of freedom of aberration correction can be increased.
[0031]
If the camera is configured using the zoom lens as described above as a photographic optical system, it is small and bright while achieving a high zoom ratio from a wide angle of view. It is possible to efficiently correct distortion aberration, field curvature, and astigmatism in the image, and to shoot with high resolution with a low-cost configuration (corresponding to claim 12).
If a portable information terminal device is configured by using the zoom lens as described above as a photographing optical system of the camera function unit, it is small and bright while sufficiently achieving a high zoom ratio from a wide angle of view. In addition, it is possible to efficiently correct distortion, field curvature, and astigmatism on the wide-angle side with a small number of lenses, and to shoot with high resolution with a low-cost configuration (corresponding to claim 13). To do).
Similarly, if a projector is configured using the zoom lens as described above as a projection optical system, it is small and bright while achieving a high zoom ratio from a wide angle of view, and a small number of lens components. Thus, distortion, field curvature, and astigmatism on the wide-angle side can be efficiently corrected, and projection can be performed with high resolution with a low-cost configuration (corresponding to claim 14).
[0032]
【Example】
Next, specific examples based on the above-described embodiment of the present invention will be described in detail. 1 to 4 are first, second, third, and fourth examples described below, and show examples of specific configurations according to specific numerical examples of the zoom lens according to the present invention. FIG. 5 shows an embodiment of a camera or a portable information terminal device according to the present invention using a zoom lens as shown in the first to fourth embodiments as a photographing optical system.
In the first to fourth embodiments showing the zoom lens according to the present invention, the configuration of the zoom lens and specific numerical examples thereof are shown.
In each of the first to fourth embodiments, the aberration is sufficiently corrected, and it is possible to cope with a light receiving element having 3 to 5 million pixels, that is, an electronic imaging element. It will be apparent from these first to fourth embodiments that a very good imaging performance can be ensured while achieving a sufficiently small size by configuring the zoom lens as in the present invention. Let's go.
[0033]
In the description related to the following first to fourth embodiments, the following various symbols are used.
f: Focal length of the entire system
F: F number
ω: Half angle of view
R: radius of curvature
D: Surface spacing
Nd: Refractive index (d is lens number = 1-10)
νd: Abbe number
K: Aspherical conical constant
A₄: Fourth-order aspheric coefficient
A₆: 6th-order aspheric coefficient
A₈: 8th-order aspheric coefficient
A₁₀: 10th-order aspheric coefficient
However, the aspherical surface used here is defined by the following equation, where C is the reciprocal of the paraxial radius of curvature (paraxial curvature) and H is the height from the optical axis.
[0034]
[Expression 1]

[0035]
[First embodiment]
FIG. 1 shows the configuration of an optical system of a zoom lens according to the 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 an aperture FA. And an optical filter OF. In this case, the first lens E1 constitutes the first lens group G1, the second lens E2 and the third lens E3 constitute the second lens group G2, and the fourth lens E4 constitutes the third lens group G3. The fifth lens E5 to the seventh lens E7 constitute a fourth lens group G4, and the eighth lens E8 constitutes a fifth lens group G5. It is supported by a support frame or the like and operates integrally for each group during zooming or the like. FIG. 1 also shows the surface numbers of the optical surfaces. 1 are used independently for each embodiment in order to avoid complication of explanation due to an increase in the number of digits of the reference code. Therefore, the same reference numerals as those in FIGS. However, they are not necessarily in common with other embodiments.
[0036]
In FIG. 1, each optical element constituting the optical system of the zoom lens includes, for example, a first lens E1, a second lens E2, a third lens E3, an aperture FA, a fourth lens E4, sequentially from the object side such as a subject. The fifth lens E5, the sixth lens E6, the seventh 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.
The first lens E1 is a positive meniscus lens convexly formed on the object side, and the first lens group G1 formed by the first lens E1 exhibits a positive focal length. That is, the first lens group G1 is composed of only one positive lens composed of the first lens E1. The second lens E2 is a negative meniscus lens that is convex on the object side, and a strong concave surface on the image side is an aspheric surface, and the third lens E3 is a positive meniscus lens that is convex on the object side. The second lens group G2 constituted by the second lens E2 and the third lens E3 exhibits a negative focal length as a whole. That is, the second lens E2 and the third lens E3 correspond to a negative lens having a strong concave surface made of an aspheric surface on the image surface side and a positive lens having a convex surface facing the object side, respectively. The fourth lens E4 is a positive meniscus lens having a convex surface on the object side and an aspherical strong convex surface on the object side. The third lens group G3 formed by the fourth lens E4 has a positive focal length. Presents.
[0037]
That is, the third lens group G3 includes a positive lens composed of the fourth lens E4 with the convex surface composed of an aspheric surface facing the object side. The stop FA disposed on the object side of the third lens group G3 operates integrally with the third lens group G3. The fifth lens E5 is a positive lens composed of a biconvex lens having a strong convex surface facing the object side, and the sixth lens E6 is a negative lens composed of a biconcave lens having a strong concave surface facing the image surface side. E5 and the sixth lens E6 are closely bonded and joined together to form a cemented lens. Further, the seventh lens E7 is a positive lens that is formed of a biconvex lens having a strong convex surface directed toward the object side, and has a convex surface on the image side. The fourth lens group G4 formed by the fifth lens E5 to the seventh lens E7 having a two-group three-lens configuration exhibits a positive focal length as a whole. The eighth lens E8 is a positive meniscus lens formed convex on the object side and having a strong convex surface on the object side as an aspherical surface. The fifth lens group G5 configured by the eighth lens E8 has a positive focal length. Presents. That is, the fifth lens group G5 is composed of only one positive lens including the eighth lens E8.
[0038]
In zooming from the wide-angle end (that is, the short focal end) to the telephoto end (that is, the long focal end), the variable interval between the groups, that is, the surface closest to the image plane of the first lens group G1, that is, the first lens. A distance D2 between the image side surface (surface number 2) of E1 and the most object side surface of the second lens group G2, that is, the object side surface (surface number 3) of the second lens E2, the second lens group The most image surface side surface of G2, that is, the image surface side surface (surface number 6) of the third lens E3, and the (object side) surface (surface number 7) of the stop FA integrated with the third lens group G3. ), The most image side surface of the third lens group G3, that is, the image side surface (surface number 9) of the fourth lens E4, and the most object side surface of the fourth lens group G4, that is, The distance D9 from the object side surface (surface number 10) of the fifth lens E5, the most image surface side surface of the fourth lens group G4, that is, the seventh lens. 7 and the fifth lens group, the distance D14 between the image side surface (surface number 14) 7 and the most object side surface of the fifth lens group G5, that is, the object side surface (surface number 15) of the eighth lens E8. The distance D16 between the most image-side surface of G5, that is, the image-side surface (surface number 16) of the eighth lens E8 and the object-side surface (surface number 17) of the optical filter OF changes, and the first The distance D2 between the lens group G1 and the second lens group G2 gradually increases, the distance D6 between the second lens group G2 and the third lens group G3 gradually decreases, and the distance D9 between the third lens group G3 and the fourth lens group G4. So that the distance D14 between the fourth lens group G4 and the fifth lens group G5 gradually increases, and the distance D16 between the fifth lens group G5 and the optical filter OF once decreases and then increases again. 1 lens group G1, 2nd lens group G2, Third lens group G3, the fourth lens group G4 and the fifth lens group G5 are moved.
[0039]
In the first embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.8 to 17.4, F = 2.81 to 4.50, respectively, by zooming. It changes in the range of ω = 37.50-14.58. The characteristics of each optical surface are as shown in the following table.
[0040]
[Table 1]
optical properties

[0041]
As shown in Table 1, the optical surfaces of the fourth surface, the eighth surface, the fourteenth surface, and the fifteenth surface are aspherical surfaces, and the parameters in the expression (2) for each aspherical surface are as follows.
Aspherical surface: 4th surface
K = -1.32427
E₄= 3.113143 × 10^-4
E₆= 2.06200 × 10^-7
E₈= -1.7479x10^-9
E₁₀= 5.72565 × 10^-11
Aspheric surface: 8th surface
K = 0.25805
E₄= −5.04632 × 10^-4
E₆= -1.37002 × 10^-5
E₈= −5.82094 × 10^-7
E₁₀= -2.775756 x 10^-8
Aspheric surface: 14th surface
K = 0
E₄= 1.99121 × 10^-4
E₆= 3.04126 × 10^-6
E₈= -7.22478 × 10^-8
E₁₀= 2.47956 × 10^-9
Aspheric surface: 15th surface
K = 0.45469
E₄= −6.43500 × 10^-5
E₆= 6.79254 × 10^-7
E₈= -3.59999 × 10^-8
E₁₀= 5.35072 × 10^-10
The variable distance D2 between the first lens group G1 and the second lens group G2, the variable distance D6 between the second lens group G2 and the stop FA integrated with the third lens group G3, the third lens group G3 And a fourth lens group G4, a variable distance D9 between the fourth lens group G4 and the fifth lens group G5, and a variable distance D16 between the fifth lens group G5 and the optical filter OF. Is changed as shown in the following table with zooming.
[0042]
[Table 2]
Variable interval

[0043]
Further, according to the above-described conditional expression (1) (conditional expression of claim 6) in the first embodiment (Φ₃/ Φ_W) Values are as follows.
Conditional expression numerical value
(Φ₃/ Φ_W) = 0.06
Therefore, the numerical value related to each conditional expression (1) described above in the first embodiment is within the range of the conditional expression.
[Second Embodiment]
FIG. 2 shows the configuration of the optical system of the zoom lens according to the second embodiment of the present invention.
The zoom lens shown in FIG. 2 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 constitutes the first lens group G1, and the second lens E2, the third lens E3, and the fourth lens E4 constitute the second lens group G2, and the fifth lens E5 and the sixth lens E5. The lens E6 constitutes the third lens group G3, the seventh lens E7 and the eighth lens E8 constitute the fourth lens group G4, and the ninth lens E9 constitutes the fifth lens group G5. These are supported by a common support frame or the like appropriate for each group, and operate integrally for each group during zooming or the like. As in the case of FIG. 1 described above, FIG. 2 also shows the surface numbers of the optical surfaces, and the reference numerals for FIG. 2 are also used independently of the other embodiments.
[0044]
In FIG. 2, the optical elements constituting the optical system of the zoom lens are, in order from the object side, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, an aperture FA, and a fifth lens E5. The sixth lens E6, the seventh 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.
The first lens E1 is a positive meniscus lens convexly formed on the object side, and the first lens group G1 formed by the first lens E1 exhibits a positive focal length. That is, the first lens group G1 is composed of only one positive lens composed of the first lens E1. The second lens E2 is a negative meniscus lens that is convex on the object side, the third lens E3 is convex on the object side, and a negative meniscus lens having a strong concave surface on the image side as an aspheric surface, and a fourth lens The lens E4 is a positive meniscus lens convexly formed on the object side, and the second lens group G2 constituted by the second lens E2 to the fourth lens E4 exhibits a negative focal length as a whole. That is, the second lens E2, the third lens E3, and the fourth lens E4 are respectively a negative lens having a concave surface facing the image surface side, a negative lens having a strong concave surface made of an aspheric surface on the image surface side, and the object side. Corresponds to a positive lens with a convex surface.
[0045]
The fifth lens E5 is composed of a biconvex lens having a strong convex surface facing the object side, a positive lens having an aspherical convex surface on the object side, and the sixth lens E6 is a biconcave lens having a strong concave surface facing the image surface side. The fifth lens E5 and the sixth lens E6 are intimately bonded and integrally joined to form a cemented lens. The third lens group G3 configured by the cemented lens of the fifth lens E5 and the sixth lens E6 exhibits a positive focal length. That is, the third lens group G3 includes a positive lens composed of the fifth lens E5 with the aspherical convex surface facing the object side. The stop FA disposed on the object side of the third lens group G3 operates integrally with the third lens group G3. The seventh lens E7 is a negative meniscus lens that is convex on the object side, and the eighth lens E8 is a biconvex lens with a strong convex surface facing the object side. The positive lens has an aspheric convex surface on the image side. The seventh lens E7 and the eighth lens E8 are intimately bonded and joined together to form a cemented lens. The fourth lens group G4 configured by the cemented lens of the seventh lens E7 and the eighth lens E8 exhibits a positive focal length as a whole. The ninth lens E9 is a positive meniscus lens that is convex on the object side and has an aspherical strong convex surface on the object side. The fifth lens group G5 configured by the ninth lens E9 has a positive focal length. Present. That is, the fifth lens group G5 is composed of only one positive lens including the ninth lens E9.
[0046]
In zooming from the wide-angle end to the telephoto end, the variable interval between the groups, that is, the most image side surface of the first lens group G1, that is, the image side surface (surface number 2) of the first lens E1. And the distance D2 between the second lens group G2 and the most object side surface, that is, the object side surface (surface number 3) of the second lens E2, and the second image group G2, the most image side surface, that is, the fourth surface. The distance D8 between the image plane side surface (surface number 8) of the lens E4 and the (object side) surface (surface number 9) of the stop FA integrated with the third lens group G3, and the third lens group G3. The most image side surface, that is, the image side surface (surface number 12) of the sixth lens E6, and the most object side surface of the fourth lens group G4, that is, the object side surface (surface number) of the seventh lens E7. 13), the distance D12 from the fourth lens group G4, the most image surface side surface of the fourth lens group G4, that is, the image surface side surface (surface number 15) of the eighth lens E8, and the The distance D15 from the most object side surface of the lens group G5, that is, the object side surface (surface number 16) of the ninth lens E9, and the most image surface side surface of the fifth lens group G5, that is, the image of the ninth lens E9. The distance D17 between the surface side surface (surface number 17) and the object side surface (surface number 18) of the optical filter OF changes, and the distance D2 between the first lens group G1 and the second lens group G2 gradually increases. The distance D8 between the second lens group G2 and the third lens group G3 is gradually reduced, the distance D12 between the third lens group G3 and the fourth lens group G4 is gradually reduced, and the fourth lens group G4 and the fifth lens group G5. The first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group so that the distance D15 of the first lens group G1 gradually increases and the distance D17 of the fifth lens group G5 and the optical filter OF gradually increases. G4 and the fifth lens group G But to move.
[0047]
In this second embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.8 to 23.2, F = 2.86 to 4.73, respectively by zooming. It changes in the range of ω = 39.29 to 11.03. The characteristics of each optical surface are as shown in the following table.
[0048]
[Table 3]
optical properties

[0049]
As shown in Table 3, the optical surfaces of the sixth surface, the tenth surface, the fifteenth surface, and the sixteenth surface are aspheric surfaces, and the parameters in the expression (2) for each aspheric surface are as follows.
Aspheric: 6th surface
K = -1.75787
E₄= 1.58668 × 10^-4
E₆= -1.31920 x 10^-6
E₈= 1.626225 × 10^-9
E₁₀= -6.35846 × 10^-11
Aspheric surface: 10th surface
K = 0.38713
E₄= -3.43631 × 10^-4
E₆= −8.45982 × 10^-6
E₈= 6.71857 × 10^-8
E₁₀= -1.77188 × 10^-8
Aspheric surface: 15th surface
K = 0
E₄= 1.36089 × 10^-4
E₆= 3.73948 × 10^-6
E₈= -1.37278 x 10^-7
E₁₀= 3.23544 × 10^-9
Aspheric surface: 16th surface
K = 0.22743
E₄= −2.885342 × 10^-5
E₆= 4.10931 × 10^-7
E₈= -1.26657 × 10^-8
E₁₀= 1.41906 × 10^-10
The variable distance D2 between the first lens group G1 and the second lens group G2, the variable distance D8 between the second lens group G2 and the stop FA integrated with the third lens group G3, the third lens group G3 Between the fourth lens group G4 and the fourth lens group G4, a variable distance D15 between the fourth lens group G4 and the fifth lens group G5, and a variable distance D17 between the fifth lens group G5 and the optical filter OF. Is changed as shown in the following table with zooming.
[0050]
[Table 4]
Variable interval

[0051]
Further, according to the above-described conditional expression (1) (conditional expression of claim 6) in the second embodiment (Φ₃/ Φ_W) Values are as follows.
Conditional expression numerical value
(Φ₃/ Φ_W) = 0.09
Therefore, the numerical value related to each conditional expression (1) described in the second embodiment is within the range of the conditional expression.
[Third embodiment]
FIG. 3 shows the configuration of the optical system of a zoom lens according to the third embodiment of the present invention.
The zoom lens shown in FIG. 3 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 constitutes the first lens group G1, and the second lens E2, the third lens E3, and the fourth lens E4 constitute the second lens group G2, and the fifth lens E5 and the sixth lens E5. The lens E6 constitutes the third lens group G3, the seventh lens E7 and the eighth lens E8 constitute the fourth lens group G4, and the ninth lens E9 constitutes the fifth lens group G5. These are supported by a common support frame or the like appropriate for each group, and operate integrally for each group during zooming or the like. As in the case of FIGS. 1 and 2 described above, FIG. 3 also shows the surface numbers of the optical surfaces, and the reference numerals for FIG. 3 are also used independently of the other embodiments.
[0052]
In FIG. 3, each optical element constituting the optical system of the zoom lens includes, in order from the object side, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, an aperture FA, and a fifth lens E5. The sixth lens E6, the seventh 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.
The first lens E1 is a positive meniscus lens convexly formed on the object side, and the first lens group G1 formed by the first lens E1 exhibits a positive focal length. That is, the first lens group G1 is composed of only one positive lens composed of the first lens E1. The second lens E2 is a negative meniscus lens convexly formed on the object side, and the third lens E3 is a biconcave lens having a strong concave surface facing the image surface side. The negative lens has an aspherical concave surface on the image surface side. The fourth lens E4 is a positive meniscus lens convexly formed on the object side, and the second lens group G2 constituted by the second lens E2 to the fourth lens E4 exhibits a negative focal length as a whole. .
[0053]
That is, the second lens E2, the third lens E3, and the fourth lens E4 are respectively a negative lens having a concave surface facing the image surface side, a negative lens having a strong concave surface made of an aspheric surface on the image surface side, and the object side. Corresponds to a positive lens with a convex surface. The fifth lens E5 is composed of a biconvex lens having a strong convex surface facing the object side, a positive lens having an aspherical convex surface on the object side, and the sixth lens E6 is a biconcave lens having a strong concave surface facing the image surface side. The fifth lens E5 and the sixth lens E6 are intimately bonded and integrally joined to form a cemented lens. The third lens group G3 configured by the cemented lens of the fifth lens E5 and the sixth lens E6 exhibits a positive focal length. That is, the third lens group G3 includes a positive lens composed of the fifth lens E5 with the aspherical convex surface facing the object side. The stop FA disposed on the object side of the third lens group G3 operates integrally with the third lens group G3. The seventh lens E7 is a negative meniscus lens that is convex on the object side, and the eighth lens E8 is a biconvex lens with a strong convex surface facing the object side. The positive lens has an aspheric convex surface on the image side. The seventh lens E7 and the eighth lens E8 are intimately bonded and joined together to form a cemented lens.
[0054]
The fourth lens group G4 configured by the cemented lens of the seventh lens E7 and the eighth lens E8 exhibits a positive focal length as a whole. The ninth lens E9 is a positive meniscus lens that is convex on the object side and has an aspherical strong convex surface on the object side. The fifth lens group G5 configured by the ninth lens E9 has a positive focal length. Present. That is, the fifth lens group G5 is composed of only one positive lens including the ninth lens E9.
In zooming from the wide-angle end to the telephoto end, the variable interval between the groups, that is, the most image side surface of the first lens group G1, that is, the image side surface (surface number 2) of the first lens E1. And the distance D2 between the second lens group G2 and the most object side surface, that is, the object side surface (surface number 3) of the second lens E2, and the second image group G2, the most image side surface, that is, the fourth surface. The distance D8 between the image plane side surface (surface number 8) of the lens E4 and the (object side) surface (surface number 9) of the stop FA integrated with the third lens group G3, and the third lens group G3. The most image side surface, that is, the image side surface (surface number 12) of the sixth lens E6, and the most object side surface of the fourth lens group G4, that is, the object side surface (surface number) of the seventh lens E7. 13), the distance D12 from the fourth lens group G4, the most image surface side surface of the fourth lens group G4, that is, the image surface side surface (surface number 15) of the eighth lens E8, and the The distance D15 from the most object side surface of the lens group G5, that is, the object side surface (surface number 16) of the ninth lens E9, and the most image surface side surface of the fifth lens group G5, that is, the image of the ninth lens E9. The distance D17 between the surface side surface (surface number 17) and the object side surface (surface number 18) of the optical filter OF changes, and the distance D2 between the first lens group G1 and the second lens group G2 gradually increases. The distance D8 between the second lens group G2 and the third lens group G3 is gradually reduced, the distance D12 between the third lens group G3 and the fourth lens group G4 is gradually reduced, and the fourth lens group G4 and the fifth lens group G5. The first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group so that the distance D15 of the first lens group G1 gradually increases and the distance D17 of the fifth lens group G5 and the optical filter OF gradually increases. G4 and the fifth lens group G But to move.
[0055]
In the third embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 5.8 to 29.0, F = 2.89 to 5.14, respectively, by zooming. It changes in the range of ω = 39.27 to 8.84. The characteristics of each optical surface are as shown in the following table.
[0056]
[Table 5]
optical properties

[0057]
As shown in Table 5, the optical surfaces of the sixth surface, the tenth surface, the fifteenth surface, and the sixteenth surface are aspheric surfaces, and the parameters in the expression (2) for each aspheric surface are as follows.
[0058]
Aspheric: 6th surface
K = −2.51049
E₄= 2.35049 × 10^-4
E₆= -2.40097 × 10^-6
E₈= 1.31014 × 10^-8
E₁₀= -1.04766 × 10^-10
Aspheric surface: 10th surface
K = 0.45216
E₄= -2.73061 × 10^-4
E₆= −7.1845 × 10^-6
E₈= 2.31431 × 10^-7
E₁₀= -1.62907 x 10^-8
Aspheric surface: 15th surface
K = 0
E₄= 2.07405 × 10^-4
E₆= 4.34935 × 10^-6
E₈= 7.95793 × 10^-9
E₁₀= −7.004025 × 10^-10
Aspheric surface: 16th surface
K = −0.00380
E₄= -1.60512 x 10^-5
E₆= 7.67204 × 10^-7
E₈= -1.57787 × 10^-8
E₁₀= 1.273392 × 10^-10
The variable distance D2 between the first lens group G1 and the second lens group G2, the variable distance D8 between the second lens group G2 and the stop FA integrated with the third lens group G3, the third lens group G3 Between the fourth lens group G4 and the fourth lens group G4, a variable distance D15 between the fourth lens group G4 and the fifth lens group G5, and a variable distance D17 between the fifth lens group G5 and the optical filter OF. Is changed as shown in the following table with zooming.
[0059]
[Table 6]
Variable interval

[0060]
Further, according to the above-described conditional expression (1) (conditional expression of claim 6) in the third embodiment (Φ₃/ Φ_W) Values are as follows.
Conditional expression numerical value
(Φ₃/ Φ_W) = 0.12
Therefore, the numerical value related to each conditional expression (1) described in the third embodiment is within the range of the conditional expression.
[Fourth embodiment]
FIG. 4 shows the configuration of the optical system of the zoom lens according to the 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 an aperture FA. And an optical filter OF. In this case, the first lens E1 constitutes the first lens group G1, the second lens E2 and the third lens E3 constitute the second lens group G2, and the fourth lens E4 and the fifth lens E5 The third lens group G3, the sixth lens E6 and the seventh lens E7 constitute the fourth lens group G4, and the eighth lens E8 constitutes the fifth lens group G5. Are supported by an appropriate common support frame or the like, and operate integrally for each group during zooming or the like. As in the case of FIGS. 1 to 3 described above, FIG. 4 also shows the surface numbers of the optical surfaces, and the reference numerals for FIG. 4 are also used independently of the other embodiments.
In FIG. 4, each optical element constituting the optical system of the zoom lens includes, in order from the object side, a first lens E1, a second lens E2, a third lens E3, an aperture FA, a fourth lens E4, and a fifth lens E5. The sixth lens E6, the seventh 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.
[0061]
The first lens E1 is a positive meniscus lens convexly formed on the object side, and the first lens group G1 formed by the first lens E1 exhibits a positive focal length. That is, the first lens group G1 is composed of only one positive lens composed of the first lens E1. The second lens E2 is a negative meniscus lens that is convex on the object side and has a strong concave surface on the image side as an aspheric surface, and the third lens E3 is a positive meniscus lens that is convex on the object side, The second lens group G2 configured by the second lens E2 and the third lens E3 exhibits a negative focal length as a whole. That is, the second lens E2 and the third lens E3 correspond to a negative lens having a strong concave surface made of an aspheric surface on the image surface side and a positive lens having a convex surface facing the object side, respectively. The fourth lens E4 is composed of a biconvex lens having a strong convex surface facing the object side, a positive lens having an aspherical convex surface on the object side, and the fifth lens E5 is a biconcave lens having a strong concave surface facing the image surface side. The fourth lens E4 and the fifth lens E5 are intimately bonded and integrally joined to form a cemented lens. The third lens group G3 configured by the cemented lens of the fourth lens E4 and the fifth lens E5 exhibits a positive focal length.
[0062]
That is, the third lens group G3 includes a positive lens composed of the fourth lens E4 with the convex surface composed of an aspheric surface facing the object side. The stop FA disposed on the object side of the third lens group G3 operates integrally with the third lens group G3. The sixth lens E6 is a negative meniscus lens convexly formed on the object side, and the seventh lens E7 is a biconvex lens having a strong convex surface facing the object side, and a positive lens having an aspherical convex surface on the image side The sixth lens E6 and the seventh lens E7 are intimately bonded and joined together to form a cemented lens. The fourth lens group G4 configured by the cemented lens of the sixth lens E6 and the seventh lens E7 exhibits a positive focal length as a whole.
[0063]
The eighth lens E8 is a positive meniscus lens that is convex on the object side and has an aspherical strong convex surface on the object side. The fifth lens group G5 configured by the eighth lens E8 has a positive focal length. Present. That is, the fifth lens group G5 is composed of only one positive lens including the eighth lens E8.
In zooming from the wide-angle end to the telephoto end, the variable interval between the groups, that is, the most image side surface of the first lens group G1, that is, the image side surface (surface number 2) of the first lens E1. And the distance D2 from the most object side surface of the second lens group G2, that is, the object side surface (surface number 3) of the second lens E2, and the most image side surface of the second lens group G2, that is, the third surface. The distance D6 between the image plane side surface (surface number 6) of the lens E3 and the (object side) surface (surface number 7) of the stop FA integrated with the third lens group G3, and the third lens group G3. The most image side surface, that is, the image side surface (surface number 10) of the fifth lens E5, and the most object side surface of the fourth lens group G4, that is, the object side surface (surface number) of the sixth lens E6. 11), the most image surface side surface of the fourth lens group G4, that is, the image surface side surface (surface number 13) of the seventh lens E7, The distance D13 from the most object side surface of the lens group G5, that is, the object side surface (surface number 14) of the eighth lens E8, and the most image surface side surface of the fifth lens group G5, that is, the image of the eighth lens E8. The distance D15 between the surface side (surface number 15) and the object side surface (surface number 16) of the optical filter OF changes, and the distance D2 between the first lens group G1 and the second lens group G2 gradually increases. The distance D6 between the second lens group G2 and the third lens group G3 gradually decreases, the distance D10 between the third lens group G3 and the fourth lens group G4 increases once, and then decreases. The first lens group G1, the second lens group G2, the third lens group G5, the distance D13 gradually increases, and the distance D15 between the fifth lens group G5 and the optical filter OF increases once and then decreases. Lens group G3, fourth Lens group G4 and the fifth lens group G5 are moved.
[0064]
In the fourth embodiment, the focal length f, F number F, and half angle of view ω of the entire system are f = 7.32 to 29.0, F = 3.35 to 5.15, respectively, by zooming. It changes in the range of ω = 31.47-8.83. The characteristics of each optical surface are as shown in the following table.
[0065]
[Table 7]
optical properties

[0066]
As shown in Table 7, the optical surfaces of the fourth surface, the eighth surface, the thirteenth surface, and the fourteenth surface are aspherical surfaces, and the parameters in the expression (2) for each aspherical surface are as follows.
[0067]
Aspherical surface: 4th surface
K = -1.112956
E₄= 3.16892 × 10^-4
E₆= 2.49202 × 10^-6
E₈= -3.777 180 x 10^-8
E₁₀= 3.71359 × 10^-10
Aspheric surface: 8th surface
K = 0.30911
E₄= -3.39887 × 10^-4
E₆= -9.230070 × 10^-6
E₈= 1.48532 × 10^-7
E₁₀= -1.82190 × 10^-8
Aspheric surface: 13th surface
K = 0
E₄= −8.887228 × 10^-5
E₆= -3.31749 × 10^-7
E₈= 6.24667 × 10^-8
E₁₀= -1.01903x10^-8
Aspheric surface: 14th surface
K = 0.01798
E₄= −4.56125 × 10^-5
E₆= 1.679901 × 10^-7
E₈= 5.14670 × 10^-9
E₁₀= -1.30259 × 10^-10
The variable distance D2 between the first lens group G1 and the second lens group G2, the variable distance D6 between the second lens group G2 and the stop FA integrated with the third lens group G3, the third lens group G3 Variable distance D10 between the fourth lens group G4, a variable distance D13 between the fourth lens group G4 and the fifth lens group G5, and a variable distance D15 between the fifth lens group G5 and the optical filter OF. Is changed as shown in the following table with zooming.
[0068]
[Table 8]
Variable interval

[0069]
Further, according to the above-described conditional expression (1) (conditional expression of claim 6) in the fourth embodiment (Φ₃/ Φ_W) Values are as follows.
[0070]
Conditional expression numerical value
(Φ₃/ Φ_W) = 0.22
Therefore, the numerical value related to each conditional expression (1) described in the fourth embodiment is within the range of the conditional expression.
5 to 7 show aberration curves of spherical aberration, astigmatism and distortion in the zoom lens shown in FIG. 1 according to the first embodiment described above. Of these, FIG. FIG. 6 is an aberration curve diagram at the intermediate focal length, and FIG. 7 is an aberration curve diagram at the telephoto end. In each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, and the broken line represents meridional.
[0071]
8 to 10 show aberration curves of spherical aberration, astigmatism and distortion in the zoom lens shown in FIG. 2 according to the second embodiment described above. FIG. 8 shows aberrations at the wide angle end. 9 is an aberration curve diagram at the intermediate focal length, and FIG. 10 is an aberration curve diagram at the telephoto end. In this case as well, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional.
11 to 13 show aberration curves of spherical aberration, astigmatism, and distortion in the zoom lens shown in FIG. 3 according to the third embodiment described above, and FIG. 11 shows aberrations at the wide-angle end. 12 is an aberration curve diagram at the intermediate focal length, and FIG. 13 is an aberration curve diagram at the telephoto end. Also in this case, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents sagittal, the broken line represents meridional, the thick line represents the d line, and the thin line represents the g line. .
[0072]
14 to 16 show aberration curves of spherical aberration, astigmatism and distortion in the zoom lens shown in FIG. 4 according to the fourth embodiment described above, and FIG. FIG. 15 is an aberration curve diagram at the intermediate focal length, and FIG. 16 is an aberration curve diagram at the telephoto end. In this case as well, in each aberration curve diagram, the broken line in the spherical aberration diagram represents the sine condition, the solid line in the astigmatism diagram represents the sagittal, and the broken line represents the meridional.
According to the aberration curve diagrams of FIGS. 5 to 16, according to the zoom lens having the configuration shown in FIGS. 1 to 4 according to the first to fourth examples of the present invention described above, the aberration is It can be seen that it is corrected or suppressed well.
Next, referring to FIG. 17 to FIG. 19 for one embodiment of a camera constructed by adopting the zoom lens according to the present invention as shown in the first to fourth embodiments described above as a photographing optical system. To explain. FIGS. 17A and 17B are perspective views showing the appearance of the camera as seen from the front side which is the object, that is, the subject side, and FIG. 18 shows the appearance of the camera as seen from the back side which is the photographer side. FIG. 19 is a perspective view, and FIG. 19 is a block diagram showing a functional configuration of the camera. Although a camera is described here, a camera 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. Such a portable information terminal device also includes substantially the same function and configuration as a camera although the appearance is slightly different. Even if the zoom lens according to the present invention is adopted in such a portable information terminal device, Good.
[0073]
As shown in FIGS. 17 and 18, the camera includes a photographing 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. Furthermore, as shown in FIG. 19, 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 includes a photographic lens 101 and a light receiving element 201 as an area sensor such as a CCD (charge coupled device) imaging device, and is an object to be photographed, that is, a subject formed by the photographic lens 101 that is a photographing optical system. The image is read by the light receiving element 201. As the photographing lens 101, the zoom lens according to the present invention as described in the first to fourth embodiments is used.
The output of the light receiving element 201 is processed by the signal processing device 202 controlled by the 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 the image processing device 203 which is also controlled by the central processing unit 204 and then recorded in the semiconductor memory 205 such as a nonvolatile memory. In this case, the semiconductor memory 205 may be a memory card loaded in the memory card slot 109 or a semiconductor memory built in the camera body.
[0074]
The liquid crystal monitor 106 can display an image being photographed, or can display an image recorded in the semiconductor memory 205. The image recorded in the semiconductor memory 205 can also be transmitted to the outside via a communication card 206 or the like loaded in the communication card slot 110.
When the camera is carried, the photographic lens 101 is in the retracted state and buried in the camera body as shown in FIG. 17A. When the user operates the power switch 108 to turn on the power, FIG. (B), the lens barrel is extended and protrudes from the camera body. At this time, in the lens barrel of the photographing lens 101, the optical systems of the respective groups constituting the zoom lens are arranged at the wide-angle end, for example, and the arrangement of the respective group optical systems is operated by operating the zoom lever 103. Is changed, and any zooming operation between the telephoto end and the wide-angle end can be performed. Desirably, the viewfinder 104 is also scaled in conjunction with a change in the angle of view of the photographic lens 101.
In many cases, focusing is performed by half-pressing the shutter button 102. In a zoom lens (a zoom lens defined in claims 1 to 15 or shown in the first to fourth embodiments) composed of five groups of positive-negative-positive-positive-positive according to the present invention. Focusing can be performed by moving the fifth lens group G5, moving the entire system, moving the light receiving element 201, or the like. The fifth lens group G5 can be configured to be small and lightweight with a single lens. If the method of moving is used, focusing can be performed at high speed and easily. When the shutter button 102 is further pushed down to the fully depressed state, photographing is performed, and then the processing as described above is performed.
[0075]
When the image recorded in the semiconductor memory 205 is displayed on the liquid crystal monitor 106 or transmitted to the outside via the communication card 206 or the like, the operation button 107 is operated in a predetermined manner. 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, the zoom lens as shown in the first to fourth embodiments can be used as the photographing optical system in the above-described camera or portable information terminal device. Therefore, it is possible to achieve a small camera or portable information terminal device with high image quality using a light receiving element of 3 to 5 million pixel class. In this case, the portable information terminal device can take a high-quality image and transmit the image to the outside.
This type of zoom lens is suitable not only for a photographing optical system in a camera or the like, but also for a projection optical system in a projector, and is shown in the first to fourth embodiments described above (or claim 1). The present invention may be implemented as a projector configured using a zoom lens (defined in claim 15) as a projection optical system.
[0076]
【The invention's effect】
As described above, according to the present invention, in order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the third lens having a positive refractive power. Zoom using a configuration of five or more positive-negative-positive-positive-positive groups in which a lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power are arranged. In a lens, while achieving a high zoom ratio from a wide angle of view, it is small and bright, and has high resolution corresponding to an image sensor with 3 to 5 million pixels, with a small number of lens components and low cost. A zoom lens, a camera, a portable information terminal device, and a projector that can be obtained can be provided.
In particular, according to the zoom lens of the first aspect of the present invention, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the positive refractive power in order from the object side. In a zoom lens comprising a third lens group having, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, at least the second lens group and the third lens group The second lens group includes a negative lens having a strong concave surface that forms an aspherical surface directed toward the image plane side, thereby performing a zooming operation by moving the fourth lens group. While achieving a high zoom ratio from the angle of view, it is small and bright, and high resolution corresponding to an image sensor with 3 to 5 million pixels can be obtained at a low cost with a small number of lens components. Distortion, field curvature and Astigmatism becomes possible to efficiently correct.
[0077]
According to the zoom lens of claim 2 of the present invention, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the positive refractive power in order from the object side. In a zoom lens in which a third lens group having a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power are arranged, at the time of zooming from the wide angle end to the telephoto end, The distance between the first lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the distance between the third lens group and the fourth lens group is decreased. A zooming operation is performed by moving the lens group, the third lens group, and the fourth lens group, and the second lens group is a negative lens having a strong concave surface that forms an aspheric surface facing the image surface side. By including this, a high zoom ratio from a wide angle of view is achieved. However, it is possible to obtain a small, bright, and high resolving power, particularly with a small number of lens elements, at low cost, and to efficiently correct distortion, curvature of field and astigmatism on the wide angle side. Is possible.
[0078]
According to a zoom lens according to a third aspect of the present invention, the zoom lens according to the first or second aspect, wherein the first lens group is composed of one positive lens, and in particular, a small number of lens components. And further downsizing is possible. According to the zoom lens of claim 4 of the present invention, in the zoom lens of claim 1 or claim 2, the second lens group is a negative lens with a strong concave surface directed sequentially from the object side to the image plane side. By disposing a lens and a positive lens having a convex surface facing the object side, in particular, a lens configuration that achieves a zoom ratio of about 3 to 4 can be further simplified. According to the zoom lens of claim 5 of the present invention, in the zoom lens of claim 1 or 2, the second lens group is a negative lens having a concave surface directed sequentially from the object side to the image surface side. In addition, by disposing the negative lens and the positive lens having the convex surface directed toward the object side, a lens configuration that achieves a zoom ratio exceeding 4 can be more efficiently configured.
[0079]
According to the zoom lens of claim 6 of the present invention, in the zoom lens of claim 1 or 2, the third lens group has a refractive power of Φ of the third lens group.₃And the refractive power of the entire system is Φ_WAs
Conditional expression:
0.05 <Φ₃/ Φ_W<1.0
In particular, it is possible to efficiently correct the spherical aberration of the divergent light beam incident from the second lens group.
According to a zoom lens of a seventh aspect of the present invention, in the zoom lens according to the sixth aspect of the present invention, in particular, the third lens group moves integrally with the stop during zooming, and in particular, a light beam for correcting aberrations. It is possible to effectively limit aberrations and perform aberration correction more efficiently.
According to the zoom lens of claim 8 of the present invention, in the zoom lens of claim 7, the third lens group includes a positive lens having a convex surface formed with an aspheric surface facing the object side. In particular, it is possible to efficiently correct the spherical aberration of the light beam limited by the stop.
[0080]
According to a zoom lens of a ninth aspect of the present invention, in the zoom lens of the first or second aspect, the fifth lens group is composed of one positive lens. It is possible to reduce the weight by using a small number of the fifth lens group that makes the light incident on the electronic imaging element parallel light and adjusts the overall aberration, and the focusing speed by the fifth lens group can also be improved.
According to a zoom lens of a tenth aspect of the present invention, in the zoom lens according to the ninth aspect, in particular, the fifth lens group includes at least one aspheric surface. By reducing the weight of the fifth lens group that converts the incident light into the element into parallel light and adjusting the overall aberration, the focusing speed of the fifth lens group is improved, and the degree of freedom of aberration correction is increased, so that the distance from infinity is increased. Good shooting performance can be obtained up to a distance.
According to a zoom lens of an eleventh aspect of the present invention, the zoom lens according to the first or second aspect is configured such that a focusing operation on a finite distance object is performed by moving the fifth lens group. In particular, the focusing operation can be performed easily and at high speed.
[0081]
According to the camera of the twelfth aspect of the present invention, by including the zoom lens according to any one of the first to eleventh aspects as a photographing optical system, in particular, a high zoom ratio from a sufficiently wide angle of view. Small and bright while achieving the ratio, and efficiently correcting distortion, curvature of field and astigmatism on the wide-angle side, and shooting with high resolving power corresponding to an image sensor with 3 to 5 million pixels Can be realized with a small number of lenses and at a low cost.
According to the portable information terminal device of the thirteenth aspect of the present invention, the zoom lens according to any one of the first to eleventh aspects is included as a photographing optical system of the camera function unit, and therefore, it is particularly wide enough. An image sensor with 3 to 5 million pixels that achieves a high zoom ratio from the angle of view, is small and bright, and efficiently corrects distortion, curvature of field and astigmatism on the wide-angle side. It is possible to achieve high resolution imaging corresponding to the above with a small number of lens elements and at low cost.
According to the projector of the fourteenth aspect of the present invention, by including the zoom lens according to any one of the first to eleventh aspects as the projection optical system, it is particularly possible to achieve a high zoom ratio from a sufficiently wide angle of view. While achieving this ratio, it is compact and bright, and it efficiently corrects distortion, curvature of field and astigmatism on the wide-angle side, and achieves high resolution projection with a small number of lenses and at low cost. It becomes possible to do.
[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 showing 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 an aberration curve diagram showing spherical aberration, astigmatism and distortion at the wide angle end of the zoom lens according to the first embodiment of the present invention shown in FIG. 1;
FIG. 6 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the intermediate focal length of the zoom lens according to the first embodiment of the present invention shown in FIG. 1;
FIG. 7 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the telephoto end of the zoom lens according to the first embodiment of the present invention shown in FIG. 1;
FIG. 8 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the wide angle end of the zoom lens according to the second embodiment of the present invention shown in FIG. 2;
FIG. 9 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the intermediate focal length of the zoom lens according to the second embodiment of the present invention shown in FIG. 2;
FIG. 10 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the telephoto end of the zoom lens according to the second embodiment of the present invention shown in FIG. 2;
FIG. 11 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the wide angle end of the zoom lens according to the third embodiment of the present invention shown in FIG. 3;
FIG. 12 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the intermediate focal length of the zoom lens according to the third embodiment of the present invention shown in FIG. 3;
FIG. 13 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the telephoto end of the zoom lens according to the third embodiment of the present invention shown in FIG. 3;
FIG. 14 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the wide angle end of the zoom lens according to the fourth embodiment of the present invention shown in FIG. 4;
FIG. 15 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the intermediate focal length of the zoom lens according to the fourth embodiment of the present invention shown in FIG. 4;
FIG. 16 is an aberration curve diagram showing spherical aberration, astigmatism and distortion at the telephoto end of the zoom lens according to the fourth embodiment of the present invention shown in FIG. 4;
FIG. 17 is a perspective view schematically showing an external configuration of an embodiment of a camera according to the present invention as viewed from the object side,
(A) shows a state where the photographic lens is retracted in the camera body, and (b) shows a state where the photographic lens protrudes from the camera body.
18 is a perspective view schematically showing the external configuration of the camera of FIG. 17 as seen from the photographer side.
19 is a block diagram schematically showing a functional configuration of the camera of FIG.
[Explanation of symbols]
G1 first lens group
G2 second lens group
G3 Third lens group
G4 4th lens group
G5 5th lens group
E1-E9 lens
FA aperture
OF Various optical filters
101 Photography 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 apparatus
204 Central processing unit (CPU)
205 Semiconductor memory
206 Communication card, etc.

Claims (14)

In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. In a zoom lens comprising a lens group and a fifth lens group having a positive refractive power,
A zooming operation is performed by moving at least the second lens group, the third lens group, and the fourth lens group, and
The zoom lens according to claim 1, wherein the second lens group includes a negative lens having a strong concave surface formed with an aspherical surface directed toward the image plane side. In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. In a zoom lens comprising a lens group and a fifth lens group having a positive refractive power,
At the time of zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the third lens group and the fourth lens group. The zooming operation is performed by moving at least the second lens group, the third lens group, and the fourth lens group so that the interval of
The zoom lens according to claim 1, wherein the second lens group includes a negative lens having a strong concave surface formed with an aspherical surface directed toward the image plane side. The zoom lens according to claim 1, wherein the first lens group includes one positive lens. The second lens group sequentially from the object side,
A negative lens with a strong concave surface on the image side,
The zoom lens according to claim 1, wherein a positive lens having a convex surface directed toward the object side is disposed. The second lens group sequentially from the object side,
A negative lens with a concave surface facing the image surface,
A negative lens,
The zoom lens according to claim 1, wherein a positive lens having a convex surface directed toward the object side is disposed. The third lens group includes:
The refractive power of the third lens group is Φ ₃ , and the refractive power of the entire system is Φ _W.
Conditional expression:
0.05 <Φ ₃ / Φ _W <1.0
The zoom lens according to claim 1, wherein the zoom lens satisfies the following. The zoom lens according to claim 6, wherein the third lens group moves integrally with the stop during zooming. The zoom lens according to claim 7, wherein the third lens group includes a positive lens having a convex surface formed with an aspheric surface directed toward the object side. The zoom lens according to claim 1, wherein the fifth lens group includes one positive lens. The zoom lens according to claim 9, wherein the fifth lens group includes at least one aspheric surface. 3. The zoom lens according to claim 1, wherein a focusing operation on a finite object is performed by moving the fifth lens group. 4. A camera comprising the zoom lens according to any one of claims 1 to 11 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. A projector comprising the zoom lens according to any one of claims 1 to 11 as a projection optical system.

Images