JP2004286960A - Zoom lens and camera - Google Patents

Abstract

An object of the present invention is to achieve high zooming from a wide angle of view, and to obtain a small, bright, and excellent lens performance at the time of close-up shooting.
The zoom lens has a five-group configuration of positive-negative-positive-positive-positive. At the time of zooming from the wide-angle end to the telephoto end, the first lens group G1 to the fifth lens group G5 operate for each lens group, and with zooming from the wide-angle end to the telephoto end, the first lens group G1 The first lens group G1 and the third lens group G3 are respectively positioned on the object side such that the distance between the second lens group G2 is increased and the distance between the second lens group G2 and the third lens group G3 is reduced. Move towards. The fourth lens group G4 serves to maintain the characteristics of the image plane during zooming, and also acts as a zooming group to reduce the amount of movement of the first lens group G1. By moving the fourth lens group G4 and the fifth lens group G5 together, an object at a finite distance is focused.
[Selection diagram] Fig. 1

Description

【００４２】
〔第１の実施例〕
図１は、本発明の第１の実施例に係るズームレンズの光学系の構成を示している。
図１に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２レンズ群Ｇ２を構成し、第８レンズＥ８〜第１０レンズＥ１０は、第３レンズ群Ｇ３を構成し、第１１レンズＥ１１および第１２レンズＥ１２は、第４レンズ群Ｇ４を構成し、第１３レンズＥ１３は、第５レンズ群Ｇ５を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図１には、参考のために各光学面の面番号の一部も付して示している。なお、図１に対する各参照符号は、参照符号の桁数の増大による説明の煩雑化を避けるため、各実施例毎に独立に用いており、そのため共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００４３】
図１において、例えば被写体等の物体側から像面側に向かって、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、絞りＦＡ、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、そして光学フィルタＯＦの順で配置されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、両凸レンズからなる正レンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５は、像面側に凸に形成された負メニスカスレンズ、第６レンズＥ６は、両凸レンズからなる正レンズ、そして第７レンズＥ７は、両凹レンズからなる負レンズであって、これら第４レンズＥ４〜第７レンズＥ７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。
【００４４】
第８レンズＥ８は、両凸レンズからなる正レンズ、第９レンズＥ９は、 物体側に凸に形成された正メニスカスレンズ、そして第１０レンズＥ１０は、物体側に凸に形成された負メニスカスレンズであって、これら第８レンズＥ８〜第１０レンズＥ１０により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１１レンズＥ１１は、両凸レンズからなる正レンズ、そして第１２レンズＥ１２は、像面側に凸に形成された負メニスカスレンズであり、第１１レンズＥ１１と第１２レンズＥ１２は、密に接合された２枚接合レンズであって、これら第１１レンズＥ１１と第１２レンズＥ１２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１３レンズＥ１３は、両凸レンズからなる正レンズであり、この第１３レンズＥ１３のみによって、正の焦点距離を有する第５レンズ群Ｇ５を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第３レンズ群Ｇ３との間の距離を一定として第３レンズ群Ｇ３に一体的に支持されている。第５レンズ群Ｇ５である第１３レンズＥ１３の像面側に配置された光学フィルタＯＦは、必要に応じて、固体撮像素子のカバーガラスを含んでいて、各種の光学フィルタリング機能を有するとともに、固体撮像素子に一体的に保持される。
【００４５】
第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第２レンズ群Ｇ２の物体側から２番目に位置する第５レンズＥ５の物体側の面である第８面、第３レンズ群Ｇ３の最も物体側に位置する第８レンズＥ８の物体側の面である第１５面、そして第５レンズ群Ｇ５を構成する第１３レンズＥ１３の物体側の面である第２４面をそれぞれ非球面としている。
この第１の実施例においては、全系の焦点距離ｆ、ＦナンバーＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜４１．０，Ｆ＝２．５５〜３．１６，ω＝３９．０２〜６．０８の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００４６】
【表１】
光学特性

【００４７】
表１において「（非球面）」と記した第６面、第８面、第１５面および第２４面の各光学面が非球面であり、各非球面における先に述べた式（１２）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝２．０４６５３×１０^−４
Ａ_６＝−１．６４９１４×１０^−６
Ａ_８＝９．７６４８９×１０^−９
Ａ_１０＝−２．０２９５２×１０^−１１
非球面：第８面
Ｋ＝０
Ａ_４＝−６．８７８２９×１０^−５
Ａ_６＝−９．５０６５７×１０^−７
Ａ_８＝３．６０２３６×１０^−８
Ａ_１０＝−６．７０７４０×１０^−１０
【００４８】
非球面：第１５面
Ｋ＝０
Ａ_４＝−５．５２８９９×１０^−５
Ａ_６＝−３．８０３６７×１０^−８
Ａ_８＝−５．１５３９６×１０^−１０
Ａ_１０＝−５．４５９０２×１０^−１２
非球面：第２４面
Ｋ＝０
Ａ_４＝−５．０８３９８×１０^−５
Ａ_６＝１．４３３７９×１０^−７
Ａ_８＝−６．５４９４０×１０^−９
Ａ_１０＝６．３４８５２×１０^−１１
【００４９】
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２レンズ群Ｇ２と絞りＦＡとの間の間隔Ｄ_１３、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_２０、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の間隔Ｄ_２３、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の間隔Ｄ_２５は、可変であり、これら可変間隔Ｄ_５，Ｄ_１３，Ｄ_２０，Ｄ_２３，Ｄ_２５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２】
可変間隔

【００５１】
なお、この第１の実施例における中間域の無限遠および近距離物体についての３次収差係数値は、それぞれ次の表３および表４に示すようになる。但し、表中の各記号は、それぞれ以下をあらわしている。
ＳＡ： 球面収差係数
ＣＭ： コマ収差係数
ＡＳ： 非点収差係数
ＤＳＴ： 歪曲収差係数
ＬＰＦ： ローパスフィルター
【００５２】
【表３】
無限遠物体

【００５３】
【表４】
０．５ｍの近距離物体

【００５４】
これらの収差係数によれば、共役長０．５ｍという近距離まで近寄っているにもかかわらず、収差変動が非常に小さいことから、本発明のこの実施例に係る合焦方式が優れていることがわかる。
【００５５】
〔第２の実施例〕
図２は、本発明の第２の実施例に係るズームレンズの光学系の構成を示している。
図２に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２レンズ群Ｇ２を構成し、第８レンズＥ８〜第１０レンズＥ１０は、第３レンズ群Ｇ３を構成し、第１１レンズＥ１１および第１２レンズＥ１２は、第４レンズ群Ｇ４を構成し、第１３レンズＥ１３は、第５レンズ群Ｇ５を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図２には、参考のために各光学面の面番号も付して示している。なお、図２に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００５６】
図２において、例えば被写体等の物体側から像面側に向かって、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、絞りＦＡ、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、そして光学フィルタＯＦの順で配置されており、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。
【００５７】
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、両凸レンズからなる正レンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、第６レンズＥ６は、両凸レンズからなる正レンズ、そして第７レンズＥ７は、像面側に凸に形成された負メニスカスレンズであり、第６レンズＥ６と第７レンズＥ７は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第７レンズＥ７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。
【００５８】
第８レンズＥ８は、両凸レンズからなる正レンズ、第９レンズＥ９も、両凸レンズからなる正レンズ、そして第１０レンズＥ１０は、物体側に凸に形成された負メニスカスレンズであって、これら第８レンズＥ８〜第１０レンズＥ１０により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１１レンズＥ１１は、両凸レンズからなる正レンズ、そして第１２レンズＥ１２は、像面側に凸に形成された負メニスカスレンズであり、第１１レンズＥ１１と第１２レンズＥ１２は、密に接合された２枚接合レンズであって、これら第１１レンズＥ１１と第１２レンズＥ１２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１３レンズＥ１３は、両凸レンズからなる正レンズであり、この第１３レンズＥ１３のみによって、正の焦点距離を有する第５レンズ群Ｇ５を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第３レンズ群Ｇ３との間の距離を一定として第３レンズ群Ｇ３に一体的に支持されている。第５レンズ群Ｇ５である第１３レンズＥ１３の像面側に配置された光学フィルタＯＦは、必要に応じて、固体撮像素子のカバーガラスを含んでいて、各種の光学フィルタリング機能を有するとともに、固体撮像素子に一体的に保持される。
【００５９】
第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第２レンズ群Ｇ２の物体側から２番目に位置する第５レンズＥ５の物体側の面である第８面、第３レンズ群Ｇ３の最も物体側に位置する第８レンズＥ８の物体側の面である第１４面、そして第５レンズ群Ｇ５を構成する第１３レンズＥ１３の物体側の面である第２３面をそれぞれ非球面としている。
この第２の実施例においては、全系の焦点距離ｆ、ＦナンバーＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜２８．８，Ｆ＝２．１６〜３．００，ω＝３８．９４〜８．５６の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００６０】
【表５】
光学特性

【００６１】
表５において「（非球面）」と記した第６面、第８面、第１４面および第２３面の各光学面が非球面であり、各非球面における先に述べた式（１２）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝１．９１１６０×１０^−４
Ａ_６＝−１．６９６０５×１０^−６
Ａ_８＝１．１０８０９×１０^−８
Ａ_１０＝−３．０６５４９×１０^−１１
非球面：第８面
Ｋ＝０
Ａ_４＝−５．５３５１３×１０^−５
Ａ_６＝４．１０９４９×１０^−７
Ａ_８＝−３．５５１０４×１０^−９
Ａ_１０＝−１．１５１８６×１０^−１０
【００６２】
非球面：第１４面
Ｋ＝０
Ａ_４＝−７．０６７６５×１０^−５
Ａ_６＝−９．８４２７５×１０^−８
Ａ_８＝４．５５３６３×１０^−１０
Ａ_１０＝−１．０９６０８×１０^−１０
非球面：第２３面
Ｋ＝０
Ａ_４＝−３．７１７１２×１０^−５
Ａ_６＝４．４１２８８×１０^−９
Ａ_８＝−３．１６７７３×１０^−９
Ａ_１０＝２．７６４０４×１０^−１１
【００６３】
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２レンズ群Ｇ２と絞りＦＡとの間の間隔Ｄ_１２、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９、そして第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の間隔Ｄ_２２、は、可変であり、これら可変間隔Ｄ_５，Ｄ_１２，Ｄ_１９，Ｄ_２２は、ズーミングに伴って次表のように変化させられる。なお、この場合、第５レンズ群Ｇ５と光学フィルタＯＦとの間の間隔は固定である（請求項２）。
【００６４】
【表６】
可変間隔

【００６５】
〔第３の実施例〕
図３は、本発明の第３の実施例に係るズームレンズの光学系の構成を示している。
図３に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２レンズ群Ｇ２を構成し、第８レンズＥ８〜第１０レンズＥ１０は、第３レンズ群Ｇ３を構成し、第１１レンズＥ１１および第１２レンズＥ１２は、第４レンズ群Ｇ４を構成し、第１３レンズＥ１３は第５レンズ群Ｇ５を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図３には、参考のために各光学面の面番号も付して示している。
なお、図３に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００６６】
図３において、例えば被写体等の物体側から像面側に向かって、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、絞りＦＡ、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、そして光学フィルタＯＦの順で配置されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、両凸レンズからなる正レンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。
【００６７】
第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、第６レンズＥ６は、両凸レンズからなる正レンズ、そして第７レンズＥ７は、両凹レンズからなる負レンズであり、第６レンズＥ６と第７レンズＥ７は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第７レンズＥ７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。第８レンズＥ８は、両凸レンズからなる正レンズ、第９レンズＥ９も、両凸レンズからなる正レンズ、そして第１０レンズＥ１０は、物体側に凸に形成された負メニスカスレンズであって、これら第８レンズＥ８〜第１０レンズＥ１０により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１１レンズＥ１１は、両凸レンズからなる正レンズ、そして第１２レンズＥ１２は、像面側に凸に形成された負メニスカスレンズであり、第１１レンズＥ１１と第１２レンズＥ１２は、密に接合された２枚接合レンズであって、これら第１１レンズＥ１１と第１２レンズＥ１２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。
【００６８】
第１３レンズＥ１３は、両凸レンズからなる正レンズであり、この第１３レンズＥ１３のみによって、正の焦点距離を有する第５レンズ群Ｇ５を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第３レンズ群Ｇ３との間の距離を一定として第３レンズ群Ｇ３に一体的に支持されている。第５レンズ群Ｇ５である第１３レンズＥ１３の像面側に配置された光学フィルタＯＦは、必要に応じて、固体撮像素子のカバーガラスを含んでいて、各種の光学フィルタリング機能を有するとともに、固体撮像素子に一体的に保持される。
第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第２レンズ群Ｇ２の物体側から２番目に位置する第５レンズＥ５の物体側の面である第８面、第３レンズ群Ｇ３の最も物体側に位置する第８レンズＥ８の物体側の面である第１４面、そして第５レンズ群Ｇ５を構成する第１３レンズＥ１３の物体側の面である第２３面をそれぞれ非球面としている。
この第３の実施例においては、全系の焦点距離ｆ、ＦナンバーＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜２８．８，Ｆ＝２．１３〜３．１０，ω＝３８．９２〜８．５５の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００６９】
【表７】
光学特性

【００７０】
表７において「（非球面）」と記した第６面、第８面、第１４面および第２３面の各光学面が非球面であり、各非球面における先に述べた式（１２）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝１．７５８０８×１０^−４
Ａ_６＝−１．５３４１５×１０^−６
Ａ_８＝１．０１５９０×１０^−８
Ａ_１０＝−２．６８７９０×１０^−１１
非球面：第８面
Ｋ＝０
Ａ_４＝−６．９３５３１×１０^−５
Ａ_６＝７．３８３３５×１０^−７
Ａ_８＝−１．５３１８４×１０^−８
Ａ_１０＝−５．４８６７８×１０^−１１
【００７１】
非球面：第１４面
Ｋ＝０
Ａ_４＝−７．２３９４４×１０^−５
Ａ_６＝−２．０６７７２×１０^−７
Ａ_８＝１．０６７４３×１０^−９
Ａ_１０＝−１．６１８４５×１０^−１０
非球面：第２３面
Ｋ＝０
Ａ_４＝−３．９４２８５×１０^−５
Ａ_６＝８．６９２２３×１０^−８
Ａ_８＝−４．８６３６５×１０^−９
Ａ_１０＝４．６１９９７×１０^−１１
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２レンズ群Ｇ２と絞りＦＡとの間の間隔Ｄ_１２、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の間隔Ｄ_２２、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の間隔Ｄ_２４は、可変であり、これら可変間隔Ｄ_５，Ｄ_１２，Ｄ_１９，Ｄ_２２，Ｄ_２４は、ズーミングに伴って次表のように変化させられる。
【００７２】
【表８】
可変間隔

【００７３】
〔第４の実施例〕
図４は、本発明の第４の実施例に係るズームレンズの光学系の構成を示している。
図４に示すズームレンズは、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、絞りＦＡおよび光学フィルタＯＦを具備している。この場合、第１レンズＥ１〜第３レンズＥ３は、第１レンズ群Ｇ１を構成し、第４レンズＥ４〜第７レンズＥ７は、第２レンズ群Ｇ２を構成し、第８レンズＥ８〜第１０レンズＥ１０は、第３レンズ群Ｇ３を構成し、第１１レンズＥ１１および第１２レンズＥ１２は、第４レンズ群Ｇ４を構成し、第１３レンズＥ１３は第５レンズ群Ｇ５を構成しており、それぞれ各レンズ群毎に適宜なる共通の支持枠等によって支持され、ズーミング等に際しては各レンズ群毎に一体的に動作する。図４には、参考のために各光学面の面番号も付して示している。
なお、図４に対する各参照符号は、先に述べたように、各実施例毎に独立に用いており、共通の参照符号を付していても他の実施例とかならずしも共通の構成ではない。
【００７４】
図４において、例えば被写体等の物体側から像面側に向かって、順次、第１レンズＥ１、第２レンズＥ２、第３レンズＥ３、第４レンズＥ４、第５レンズＥ５、第６レンズＥ６、第７レンズＥ７、絞りＦＡ、第８レンズＥ８、第９レンズＥ９、第１０レンズＥ１０、第１１レンズＥ１１、第１２レンズＥ１２、第１３レンズＥ１３、そして光学フィルタＯＦの順で配置されており、各種の光学フィルタリング機能を有する光学フィルタＯＦの背後に結像される。
第１レンズＥ１は、物体側に凸に形成された負メニスカスレンズ、第２レンズＥ２は、物体側に凸に形成された正メニスカスレンズ、そして第３レンズＥ３は、物体側に凸に形成された正メニスカスレンズであり、第１レンズＥ１と第２レンズＥ２は、密に接合された２枚接合レンズであって、これら第１レンズＥ１〜第３レンズＥ３により構成する第１レンズ群Ｇ１は、全体として正の焦点距離を呈する。第４レンズＥ４は、両凹レンズからなる負レンズ、第５レンズＥ５も、両凹レンズからなる負レンズ、第６レンズＥ６は、両凸レンズからなる正レンズ、そして第７レンズＥ７は、像面側に凸に形成された負メニスカスレンズであり、第６レンズＥ６と第７レンズＥ７は、密に接合された２枚接合レンズであって、これら第４レンズＥ４〜第７レンズＥ７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。
【００７５】
第８レンズＥ８は、物体側に凸に形成された正メニスカスレンズ、第９レンズＥ９も、物体側に凸に形成された正メニスカスレンズ、そして第１０レンズＥ１０は、物体側に凸に形成された負メニスカスレンズであって、これら第８レンズＥ８〜第１０レンズＥ１０により構成する第３レンズ群Ｇ３は、全体として正の焦点距離を呈する。第１１レンズＥ１１は、両凸レンズからなる正レンズ、そして第１２レンズＥ１２は、像面側に凸に形成された負メニスカスレンズであり、第１１レンズＥ１１と第１２レンズＥ１２は、密に接合された２枚接合レンズであって、これら第１１レンズＥ１１と第１２レンズＥ１２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１３レンズＥ１３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１３レンズＥ１３のみによって、正の焦点距離を有する第５レンズ群Ｇ５を構成している。第２レンズ群Ｇ２と第３レンズ群Ｇ３との間に配置された絞りＦＡは、第３レンズ群Ｇ３との間の距離を一定として第３レンズ群Ｇ３に一体的に支持されている。第５レンズ群Ｇ５である第１３レンズＥ１３の像面側に配置された光学フィルタＯＦは、必要に応じて、固体撮像素子のカバーガラスを含んでいて、各種の光学フィルタリング機能を有するとともに、固体撮像素子に一体的に保持される。
【００７６】
第２レンズ群Ｇ２の最も物体側に位置する第４レンズＥ４の物体側の面である第６面、第２レンズ群Ｇ２の物体側から２番目に位置する第５レンズＥ５の物体側の面である第８面、第３レンズ群Ｇ３の最も物体側に位置する第８レンズＥ８の物体側の面である第１４面、そして第５レンズ群Ｇ５を構成する第１３レンズＥ１３の物体側の面である第２３面をそれぞれ非球面としている。
この第４の実施例においては、全系の焦点距離ｆ、ＦナンバーＦ、そして半画角ωは、ズーミングにより、それぞれｆ＝５．８〜４１．０，Ｆ＝２．５６〜３．６２，ω＝３９．８６〜６．３６の範囲で変化する。各光学面および光学素子に関連する光学特性は、次表の通りである。
【００７７】
【表９】
光学特性

【００７８】
表９において「（非球面）」と記した第６面、第８面、第１４面および第２３面の各光学面が非球面であり、各非球面における先に述べた式（１２）に係るパラメータは、次の通りである。
非球面：第６面
Ｋ＝０
Ａ_４＝１．５５６１１×１０^−４
Ａ_６＝−１．１３０７３×１０^−６
Ａ_８＝５．３８０４５×１０^−９
Ａ_１０＝−１．３３３８０×１０^−１１
非球面：第８面
Ｋ＝０
Ａ_４＝−４．４７３７２×１０^−５
Ａ_６＝−１．５０６９２×１０^−７
Ａ_８＝１．０８９２３×１０^−８
Ａ_１０＝５．１７９９８×１０^−１２
【００７９】
非球面：第１４面
Ｋ＝０
Ａ_４＝−６．１８５５２×１０^−５
Ａ_６＝−２．１１２２５×１０^−７
Ａ_８＝１．８３２３４×１０^−９
Ａ_１０＝−４．８２６３９×１０^−１１
非球面：第２３面
Ｋ＝０
Ａ_４＝−６．２７９２２×１０^−５
Ａ_６＝−４．４０１５７×１０^−８
Ａ_８＝−１．８０７０８×１０^−９
Ａ_１０＝１．３５０９６×１０^−１１
第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の間隔Ｄ_５、第２レンズ群Ｇ２と絞りＦＡとの間の間隔Ｄ_１２、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の間隔Ｄ_１９、第４レンズ群Ｇ４と第５レンズ群Ｇ５との間の間隔Ｄ_２２、そして第５レンズ群Ｇ５と光学フィルタＯＦとの間の間隔Ｄ_２４は、可変であり、これら可変間隔Ｄ_５，Ｄ_１２，Ｄ_１９，Ｄ_２２，Ｄ_２４は、ズーミングに伴って次表のように変化させられる。
【００８０】
【表１０】
可変間隔

【００８１】
以上説明してきたところの第１の実施例〜第４の実施例における、第１レンズ群〜第５レンズ群の焦点距離ｆ_１〜ｆ_５、広角端におけるレンズ系全体での焦点距離ｆ_ｗ、望遠端におけるレンズ系全体での焦点距離ｆ_Ｔの各値は、次の表１１の通りである。
【００８２】
【表１１】

【００８３】
そして、本発明の第１の実施例〜第４の実施例における先に述べた本発明の条件式（１）〜（１１）に関する数値は、次の表１２および表１３の通りとなり、全ての実施例は、各条件式を満足している。
【００８４】
【表１２】

【００８５】
【表１３】

【００８６】
なお、図５は、第１の実施例のズームレンズの短焦点端における収差曲線図、図６は、第１の実施例のズームレンズの中間焦点距離における収差曲線図、そして図７は、第１の実施例のズームレンズの長焦点端における収差曲線図である。また、図８は、第２の実施例のズームレンズの短焦点端における収差曲線図、図９は、第２の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１０は、第２の実施例のズームレンズの長焦点端における収差曲線図である。同様に図１１は、第３の実施例のズームレンズの短焦点端における収差曲線図、図１２は、第３の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１３は、第３の実施例のズームレンズの長焦点端における収差曲線図である。図１４は、第４の実施例のズームレンズの短焦点端における収差曲線図、図１５は、第４の実施例のズームレンズの中間焦点距離における収差曲線図、そして図１６は、第４の実施例のズームレンズの長焦点端における収差曲線図である。これら図５〜図１６の収差曲線図中、球面収差の図における破線は正弦条件をあらわしており、非点収差の図における実線はサジタル、そして破線はメリディオナルをあらわしている。これら各収差曲線図によっても、上述した各実施例により、良好な特性が得られていることがわかる。
なお、これら各実施例に示したズームレンズを撮影レンズとして用いてカメラを構成すれば、小型で且つ広画角および高画質が得られるカメラを実現することができる。
【００８７】
【発明の効果】
以上述べたように、本発明によれば、広画角からの高変倍ズーミングが可能であるとともに、小型で明るく、しかも近距離撮影時に優れたレンズ性能を得ることも可能なズームレンズおよび小型で広画角を有し且つ高画質が得られるカメラを提供することができる。
すなわち、本発明の請求項１のズームレンズによれば、物体側から、順次、正の屈折力を有する第１レンズ群、負の屈折力を有する第２レンズ群、正の屈折力を有する第３レンズ群、正の屈折力を有する第４レンズ群および正の屈折力を有する第５レンズ群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、前記第１レンズ群〜第５レンズ群が各レンズ群毎に動作し、広角端から望遠端への変倍に伴って、前記第１レンズ群と前記第２レンズ群の間隔が大きくなるように、且つ前記第２レンズ群と前記第３レンズ群の間隔が小さくなるようにして、前記第１レンズ群および前記第３レンズ群がそれぞれ物体側へ向かって移動するとともに、前記第４レンズ群および前記第５レンズ群を一体的に移動させることによって有限遠物体に合焦させることにより、広画角からの高変倍ズーミングが可能であるとともに、小型で明るく、しかも近距離撮影時に優れたレンズ性能を得ることも可能で、特に、少ないレンズ枚数で高い性能を得て、しかも近距離撮影時にも高い性能を得ることが可能となる。
【００８８】
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、負の屈折力を有する第２レンズ群、正の屈折力を有する第３レンズ群、正の屈折力を有する第４レンズ群および正の屈折力を有する第５レンズ群を配置してなるズームレンズにおいて、前記第５レンズ群は変倍時に固定され、広角端から望遠端への変倍時に、前記第１レンズ群〜第４レンズ群が各レンズ群毎に動作して、広角端から望遠端への変倍に伴って、前記第１レンズ群と前記第２レンズ群の間隔が大きくなるように、且つ前記第２レンズ群と前記第３レンズ群の間隔が小さくなるようにして、前記第１レンズ群および前記第３レンズ群がそれぞれ物体側へ向かって移動するとともに、前記第４レンズ群および前記第５レンズ群を一体的に移動させることによって有限遠物体に合焦させることにより、特に、請求項１とは異なる構成により、少ないレンズ枚数で高い性能を得て、しかも近距離撮影時にも高い性能を得ることが可能となる。
【００８９】
本発明の請求項３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、負の屈折力を有する第２レンズ群、正の屈折力を有する第３レンズ群、正の屈折力を有する第４レンズ群および正の屈折力を有する第５レンズ群を配置してなるズームレンズにおいて、前記第２レンズ群は変倍時に固定され、広角端から望遠端への変倍時に、前記第１レンズ群と前記第３〜第５レンズ群が各レンズ群毎に動作して、広角端から望遠端への変倍に伴って、前記第１レンズ群と前記第２レンズ群の間隔が大きくなるように、且つ前記第２レンズ群と前記第３レンズ群の間隔が小さくなるようにして、前記第１レンズ群および前記第３レンズ群がそれぞれ物体側へ向かって移動するとともに、前記第４レンズ群および前記第５レンズ群を一体的に移動させることによって有限遠物体に合焦させることにより、特に、請求項１および請求項２とは異なる構成により、少ないレンズ枚数で高い性能を得て、しかも近距離撮影時にも高い性能を得ることが可能となる。
【００９０】
本発明の請求項４のズームレンズによれば、請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、近距離撮影時には、前記第４レンズ群と前記第５レンズ群とをそれぞれ独立して移動させることによって有限遠物体に合焦させることにより、特に、さらに近距離で撮影する場合に、インナーフォーカスによる像面の特性の変化を補償可能として、一層良好な性能を得ることが可能となる。
本発明の請求項５のズームレンズによれば、請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、前記第２レンズ群が、その最も像面側に、強い凹面を物体側に向けた負レンズを含むことにより、特に、広角側での軸外収差と望遠側での軸上収差をバランス良く補正することが可能となる。
【００９１】
本発明の請求項６のズームレンズによれば、請求項５のズームレンズにおいて、前記負レンズが、接合レンズであることにより、特に、球面収差と共に軸上の色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１〜請求項３のうちのいずれか１項のズームレンズにおいて、前記第３レンズ群の物体側に配置され、該第３レンズ群と一体的に構成された開口絞りをさらに含み、且つ前記第３レンズ群が、その最も物体側に、非球面を形成す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、球面収差を他の収差とは別に、ほぼ単独で補正することが可能となる。
本発明の請求項８のズームレンズによれば、請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、前記第４レンズ群および前記第５レンズ群からなる一体で移動するレンズ群が、２枚の正レンズと１枚の負レンズとで構成されることにより、特に、少ないレンズ枚数でも効率よく良好な性能を得ることが可能となる。
【００９２】
本発明の請求項９のズームレンズによれば、請求項８のズームレンズにおいて、前記第４レンズ群が、正レンズと負レンズとの接合レンズからなり、且つ前記正レンズの屈折率およびアッベ数をそれぞれＮ_４ｐおよびν_４ｐとし、前記負レンズの屈折率およびアッベ数をそれぞれＮ_４ｎおよびν_４ｎとして、条件式：
１．４５＜Ｎ_４ｐ＜１．６０
６０＜ν_４ｐ＜８５
１．６５＜Ｎ_４ｎ＜１．９５
２０＜ν_４ｎ＜３５
を満足することにより、特に、軸上の色収差を効率良く補正することが可能となる。
【００９３】
本発明の請求項１０のズームレンズによれば、請求項１〜請求項３のうちのいずれか１項のズームレンズにおいて、広角端におけるレンズ系全体での焦点距離をｆ_Ｗとし、望遠端におけるレンズ系全体での焦点距離をｆ_Ｔとし、前記第５レンズ群の焦点距離をｆ_５として、条件式：
２．５＜ｆ_５／ｆ_Ｗ＜８．５
０．３＜ｆ_５／ｆ_Ｔ＜２．０
を満足することにより、特に、結像面に入射する光線をなるべく平行に近付け、固体撮像素子等のマイクロレンズアレイを用いる撮像手段により効率良く受光す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〜請求項３のうちのいずれか１項のズームレンズにおいて、広角端から望遠端への変倍に伴って、前記第３レンズ群と前記第４レンズ群の間隔が小さくなるように、第４レンズ群が物体側へ向かって移動することにより、特に、変倍時における第１レンズ群の移動量を効率良く低減することが可能となる。
【００９４】
本発明の請求項１２のズームレンズによれば、請求項１１のズームレンズにおいて、広角端から望遠端への変倍に伴う前記第１レンズ群と前記第２レンズ群との間隔の変化量をＺＤ_１２とし、広角端から望遠端への変倍に伴う前記第３レンズ群と前記第４レンズ群との間隔の変化量をＺＤ_３４とし、広角端から望遠端への変倍に伴う前記第４レンズ群と前記第５レンズ群との間隔の変化量をＺＤ_４５とし、広角端におけるレンズ系全体での焦点距離をｆ_Ｗとして、条件式：
２．００＜ＺＤ_１２／ｆ_Ｗ＜８．００
０．３５＜ＺＤ_３４／ｆ_Ｗ＜３．４５
１．００＜ＺＤ_４５／ｆ_Ｗ＜５．００
を満足することにより、特に、前玉径や機構の大型化を招いたり、変倍を妨げたりすることなく、良好な収差補正を達成することが可能となる。
【００９５】
本発明の請求項１３のズームレンズによれば、請求項１２のズームレンズにおいて、望遠端におけるレンズ系全体での焦点距離をｆ_Ｔとし、前記第１レンズ群の焦点距離をｆ_１とし、前記第２レンズ群の焦点距離をｆ_２として、条件式：
０．２０＜｜ｆ_２／ｆ_Ｔ｜＜０．３５
１．００＜｜ｆ_１／ｆ_Ｔ｜＜３．５０
を満足することにより、特に、前玉径や機構の大型化と、収差補正との適度なバランスを達成することが可能となる。
さらに、本発明の請求項１４のカメラによれば、撮影用光学系として、前記請求項１〜請求項１２のうちのいずれか１項のズームレンズを使用してなることにより、特に、広画角からの高変倍ズーミングによる撮影が可能であるとともに、小型で明るく、しかも近距離撮影時に優れた撮影画質を得ることも可能となる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係るズームレンズの第１の実施例の光学系の構成を示す模式図である。
【図２】本発明の第１の実施の形態に係るズームレンズの第２の実施例の光学系の構成を示す模式図である。
【図３】本発明の第１の実施の形態に係るズームレンズの第３の実施例の光学系の構成を示す模式図である。
【図４】本発明の第１の実施の形態に係るズームレンズの第４の実施例の光学系の構成を示す模式図である。
【図５】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図６】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図７】本発明の第１の実施の形態に係るズームレンズの図１に示す第１の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図８】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図９】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１０】本発明の第１の実施の形態に係るズームレンズの図２に示す第２の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１１】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図１２】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１３】本発明の第１の実施の形態に係るズームレンズの図３に示す第３の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【図１４】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の短焦点端における収差特性を示す収差曲線図である。
【図１５】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の中間焦点距離における収差特性を示す収差曲線図である。
【図１６】本発明の第１の実施の形態に係るズームレンズの図４に示す第４の実施例の光学系の長焦点端における収差特性を示す収差曲線図である。
【符号の説明】
Ｇ１ 第１レンズ群
Ｇ２ 第２レンズ群
Ｇ３ 第３レンズ群
Ｇ４ 第４レンズ群
ＦＡ 絞り
ＯＦ 光学フィルタ
Ｅ１ 第１レンズ
Ｅ２ 第２レンズ
Ｅ３ 第３レンズ
Ｅ４ 第４レンズ
Ｅ５ 第５レンズ
Ｅ６ 第６レンズ
Ｅ７ 第７レンズ
Ｅ８ 第８レンズ
Ｅ９ 第９レンズ
Ｅ１０ 第１０レンズ
Ｅ１１ 第１１レンズ
Ｅ１２ 第１２レンズ
Ｅ１３ 第１３レンズ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improvement of a zoom lens that can be set to different focal lengths by individually moving a plurality of lens groups in an optical axis direction, and particularly to an electronic imaging device such as a digital still camera and a digital video camera. The present invention relates to a wide-angle and high-magnification zoom lens suitable for a camera that has been used, and a camera using such a zoom lens as a photographic optical system.
[0002]
[Prior art]
In recent years, as a photographic lens for a digital camera integrated with a lens, a 3 × zoom lens in which an angle of view at a wide-angle end is about 62 degrees has become mainstream. This is because by suppressing the angle of view and the zoom ratio to these levels, the diameter of the front lens of the taking lens and the overall length of the lens can be made compact. However, in a photographing lens for a silver halide camera, a photographing lens used as a standard is a zoom lens having a field angle of about 74 degrees at the wide angle end and a zoom ratio of about 4 to 7 times the field angle. For this reason, there is a demand for a wide-angle and high-magnification zoom lens having a specification equal to or higher than that of a silver-salt camera, also for a digital camera.
Conventionally, various proposals have been made for a zoom lens in which positive-negative-positive-positive-positive lens groups are sequentially arranged from the object side. In the past, there has been proposed a zoom lens having an angle of view at the wide-angle end of about 64 degrees and a zoom ratio of about 3 times this angle of view as described in Patent Document 1 below.
[0003]
[Patent Document 1]
JP-A-57-195213
Patent Document 2 below discloses a zoom lens having an angle of view at the wide-angle end of about 70 degrees and having a zoom ratio of 11 times or more from this angle of view. There is also disclosed a zoom lens having an angle of view of about 74 degrees at the wide-angle end and having a zoom ratio of 10 times or more from this angle of view.
[0004]
[Patent Document 2]
Japanese Patent No. 3352804
[Patent Document 3]
JP-A-10-161028
Further, in Patent Document 4, a zoom lens in which positive-negative-positive-positive-positive lens groups are sequentially arranged from the object side has a zoom ratio of about 7 to 10 times. In addition, Japanese Patent Application Laid-Open No. H11-163873 proposes a camera having an angle of view at the wide-angle end of about 66 degrees and a zoom ratio of about 5 times.
[0005]
[Patent Document 4]
JP-A-2002-98893
[Patent Document 5]
JP-A-2002-156581
[0006]
[Problems to be solved by the invention]
However, the zoom lens disclosed in Patent Document 1 has as many as 18 lenses or more and has a field angle of view of about 64 degrees at the wide-angle end, and a zoom ratio of about three times from the wide-angle end. It only covered until. Further, 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, and the number of constituent lenses is as small as 11, but rather. It has a lens performance only for a video camera, and it is difficult to achieve a resolution corresponding to an image sensor of 3 to 5 million pixels with the configuration and refractive power arrangement disclosed herein. The zoom lens disclosed in Patent Document 3 has a zoom ratio of 10 times or more from the wide-angle end having a wide angle of view of about 74 degrees, but the F-number is as dark as 4.1 at the maximum. The zoom lens disclosed in Patent Document 4 has high performance with a zoom ratio of 7 to 10 times and an F-number of about 2.5 to 4, but has a relatively large number of constituent lenses of 12 to 17 lenses. It tends to be. In the zoom lens disclosed in Patent Document 5, the number of constituent lenses is as small as about 10 to 12, but during zooming, the first lens group and the third lens group are fixed, and the second lens group is fixed. The zooming is performed by moving the fourth lens group, and the fourth lens group and the fifth lens group are used to correct the image plane position accompanying the zooming, and the fifth lens group is moved (in the case of inner focusing). Alternatively, focusing is performed by moving the entire body. Further, in any of the above-mentioned lens systems, little attention has been paid to the lens configuration at the time of short-distance shooting.
[0007]
The present invention has been made in view of the above-described circumstances, and is capable of performing high-magnification zooming from a wide angle of view, and is small, bright, and capable of obtaining excellent lens performance at the time of close-up shooting. It is an object of the present invention to provide a lens and a camera having a small size, a wide angle of view, and high image quality.
An object of claim 1 of the present invention is to provide a zoom lens capable of obtaining high performance brightly and at the time of short-distance photographing, while being compact with a small number of lenses. is there.
An object of claim 2 of the present invention is to provide a zoom lens which can obtain high performance with a small number of lenses and can obtain high performance even at the time of short-distance photographing, particularly with another configuration. .
An object of claim 3 of the present invention is to provide a zoom lens which can obtain high performance with a small number of lenses and can obtain high performance even at the time of short-distance photographing, with other configurations. .
A fourth object of the present invention is to provide a zoom lens capable of compensating for a change in characteristics of an image plane due to an inner focus and obtaining more excellent performance, particularly when photographing at a shorter distance. Is to do.
[0008]
An object of claim 5 of the present invention is to provide a zoom lens capable of correcting off-axis aberrations on the wide-angle side and on-axis aberrations on the telephoto side in a well-balanced manner.
An object of claim 6 of the present invention is to provide a zoom lens capable of efficiently correcting axial chromatic aberration as well as spherical aberration.
It is an object of claim 7 of the present invention to provide a zoom lens capable of correcting spherical aberration almost independently independently of other aberrations.
It is an object of an eighth aspect of the present invention to provide a zoom lens capable of efficiently obtaining good performance even with a small number of lenses.
An object of a ninth aspect of the present invention is to provide a zoom lens capable of efficiently correcting axial chromatic aberration.
An object of a tenth aspect of the present invention is to provide a zoom lens in which light rays incident on an image plane are brought closer to parallel as much as possible and can be efficiently received by an imaging means using a microlens array such as a solid-state imaging device. Is to do.
[0009]
An object of an eleventh aspect of the present invention is to provide a zoom lens capable of efficiently reducing the amount of movement of the first lens unit during zooming.
It is an object of a twelfth aspect of the present invention to provide a zoom lens capable of achieving satisfactory aberration correction without particularly increasing the diameter of a front lens or a mechanism or preventing zooming. It is in.
An object of a thirteenth aspect of the present invention is to provide a zoom lens capable of achieving an appropriate balance between enlargement of a front lens diameter and a mechanism and aberration correction.
An object of claim 14 of the present invention is to provide a camera which can perform shooting from a wide angle of view by high-magnification zooming, and which is small and bright, and which can also obtain excellent shooting image quality at close-up shooting. To provide.
[0010]
[Means for Solving the Problems]
The zoom lens according to the first aspect of the present invention has the following features.
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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
At the time of zooming from the wide-angle end to the telephoto end, the first lens group to the fifth lens group operate for each lens group, and with the zooming from the wide-angle end to the telephoto end, the first lens group and the fifth lens group are moved. The first lens group and the third lens group are respectively directed toward the object side such that the distance between the second lens group is increased and the distance between the second lens group and the third lens group is reduced. Move and
The fourth lens group and the fifth lens group are moved together to focus on a finite object.
[0011]
The zoom lens according to the present invention described in claim 2 achieves the above-described object by:
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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
The fifth lens group is fixed at the time of zooming, and at the time of zooming from the wide-angle end to the telephoto end, the first to fourth lens groups operate for each lens group to move from the wide-angle end to the telephoto end. The first lens is set such that the distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases as the magnification changes. The group and the third lens group move toward the object side, respectively.
The fourth lens group and the fifth lens group are moved together to focus on a finite object.
[0012]
The zoom lens according to the present invention described in claim 3 achieves the above object by:
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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
The second lens group is fixed at the time of zooming, and at the time of zooming from the wide-angle end to the telephoto end, the first lens group and the third to fifth lens groups operate for each lens group, and from the wide-angle end. With zooming to the telephoto end, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is reduced. The first lens group and the third lens group move toward the object side, respectively,
The fourth lens group and the fifth lens group are moved together to focus on a finite object.
[0013]
A zoom lens according to a fourth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the fourth lens group and the fifth lens group are used during close-up shooting. Are moved independently of each other to focus on an object at a finite distance.
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the second lens group has a strong concave surface closest to the image plane. It is characterized by including a negative lens directed toward the object side.
According to a sixth aspect of the present invention, in the zoom lens of the fifth aspect, the negative lens is a cemented lens.
A zoom lens according to a seventh aspect of the present invention is the zoom lens according to any one of the first to third aspects,
An aperture stop that is arranged on the object side of the third lens group and is configured integrally with the third lens group; and
The third lens group is characterized by including a positive lens having a convex surface forming an aspheric surface facing the object side on the most object side.
[0014]
According to an eighth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the zoom lens according to any one of the first to third aspects moves integrally with the fourth lens group and the fifth lens group. The lens group includes two positive lenses and one negative lens.
The zoom lens according to a ninth aspect of the present invention is the zoom lens according to the eighth aspect,
The fourth lens group includes a cemented lens of a positive lens and a negative lens, and
Let the refractive index and Abbe number of the positive lens be N_4pAnd ν_4pAnd the refractive index and Abbe number of the negative lens are N_4nAnd ν_4nAs the conditional expression:
1.45 <N_4p<1.60 (1)
60 <ν_4p<85 (2)
1.65 <N_4n<1.95 (3)
20 <ν_4n<35 (4)
It is characterized by satisfying.
[0015]
A zoom lens according to a tenth aspect of the present invention is the zoom lens according to any one of the first to third aspects,
Let f be the focal length of the entire lens system at the wide-angle end._WAnd the focal length of the entire lens system at the telephoto end is represented by f_TAnd the focal length of the fifth lens group is f₅As the conditional expression:
2.5 <f₅/ F_W<8.5 (5)
0.3 <f₅/ F_T<2.0 (6)
It is characterized by satisfying.
A zoom lens according to an eleventh aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the zoom lens from the wide-angle end to the telephoto end has the third lens. The fourth lens group moves toward the object side such that the distance between the group and the fourth lens group decreases.
[0016]
The zoom lens according to a twelfth aspect of the present invention is the zoom lens according to the eleventh aspect,
The amount of change in the distance between the first lens unit and the second lens unit due to zooming from the wide-angle end to the telephoto end is represented by ZD.₁₂ZD represents the amount of change in the distance between the third lens unit and the fourth lens unit due to zooming from the wide-angle end to the telephoto end.₃₄ZD represents the amount of change in the distance between the fourth lens group and the fifth lens group due to zooming from the wide-angle end to the telephoto end.₄₅And the focal length of the entire lens system at the wide-angle end is f_WAs the conditional expression:
2.00 <ZD₁₂/ F_W<8.00 (7)
0.35 <ZD₃₄/ F_W<3.45 (8)
1.00 <ZD₄₅/ F_W<5.00 (9)
It is characterized by satisfying.
[0017]
The zoom lens according to a thirteenth aspect of the present invention is the zoom lens according to the twelfth aspect,
Let f be the focal length of the entire lens system at the telephoto end._TAnd the focal length of the first lens group is f₁And the focal length of the second lens group is f₂As the conditional expression:
0.20 <| f₂/ F_T| <0.35 (10)
1.00 <| f₁/ F_T| <3.50 (11)
It is characterized by satisfying.
The camera according to the present invention described in claim 14 uses the zoom lens according to any one of claims 1 to 12 as a photographing optical system in order to achieve the above object. It is characterized by becoming.
[0018]
[Action]
That is, the zoom lens according to claim 1 of the present invention comprises, 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 third lens having a positive refractive power. A zoom lens comprising a lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, wherein at the time of zooming from the wide-angle end to the telephoto end, the first lens group to the The five lens groups operate for each lens group, and the distance between the first lens group and the second lens group increases with zooming from the wide-angle end to the telephoto end, and the second lens group The first lens group and the third lens group move toward the object side, respectively, such that the distance between the first lens group and the third lens group decreases, and the fourth lens group and the fifth lens group are integrated. Finite by moving Focusing on an object.
With such a configuration, high zooming from a wide angle of view can be achieved, and at the same time, small and bright, excellent lens performance can be obtained at the time of short-distance shooting, and in particular, high performance can be obtained with a small number of lenses. Moreover, high performance can be obtained even at the time of close-up shooting.
[0019]
The zoom lens according to claim 2 of the present invention comprises, 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 third lens having a positive refractive power. In a zoom lens comprising a lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, the fifth lens group is fixed at the time of zooming and moves from the wide-angle end to the telephoto end. When the magnification is changed, the first lens group to the fourth lens group operate for each lens group, and as the magnification changes from the wide-angle end to the telephoto end, the first lens group and the second lens group The first lens group and the third lens group move toward the object side, respectively, such that the distance between the second lens group and the third lens group is reduced so as to increase the distance, and The fourth lens group and the fifth lens group It focuses on finite distance object by moving the body to.
With such a configuration, in particular, with a configuration different from the first aspect, high performance can be obtained with a small number of lenses, and high performance can be obtained even at the time of short-distance shooting.
[0020]
The zoom lens according to claim 3 of the present invention includes, 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, In a zoom lens having a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power, the second lens group is fixed at the time of zooming, and changes from the wide-angle end to the telephoto end. At the time of magnification, the first lens group and the third to fifth lens groups operate for each lens group, and the first and second lens groups and the second lens are changed with zooming from the wide-angle end to the telephoto end. The first lens group and the third lens group move toward the object side such that the distance between the groups increases and the distance between the second lens group and the third lens group decreases. Together with the fourth lens group and the fifth lens It focuses on finite distance object by moving integrally with.
With such a configuration, especially with a configuration different from the first and second aspects, high performance can be obtained with a small number of lenses, and high performance can be obtained even at the time of short-distance shooting.
[0021]
A zoom lens according to a fourth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the fourth lens group and the fifth lens group are independent of each other during close-up shooting. And move it to focus on a finite object.
With such a configuration, particularly when photographing at a shorter distance, it is possible to compensate for a change in the characteristics of the image plane due to the inner focus, and to obtain better performance.
A zoom lens according to a fifth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the second lens group has the strongest concave surface on the object side and the strongest concave surface on the object side. Includes negative lens aimed at.
With such a configuration, particularly, off-axis aberrations on the wide-angle side and on-axis aberrations on the telephoto side can be corrected with good balance.
In a zoom lens according to a sixth aspect of the present invention, in the zoom lens according to the fifth aspect, the negative lens is a cemented lens.
With such a configuration, in particular, axial chromatic aberration can be efficiently corrected together with spherical aberration.
[0022]
A zoom lens according to a seventh aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the zoom lens is disposed on the object side of the third lens group, and is integrated with the third lens group. The third lens group further includes a positive lens having a convex surface forming an aspherical surface facing the object side, closest to the object side. With such a configuration, particularly, spherical aberration can be corrected almost independently independently of other aberrations.
A zoom lens according to an eighth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the integrally moving lens group including the fourth lens group and the fifth lens group is provided. It consists of two positive lenses and one negative lens.
With such a configuration, particularly, good performance can be efficiently obtained with a small number of lenses.
[0023]
In a zoom lens according to a ninth aspect of the present invention, in the zoom lens according to the eighth aspect, the fourth lens group comprises a cemented lens of a positive lens and a negative lens, and has a refractive index and an Abbe number of the positive lens, respectively. N_4pAnd ν_4pAnd the refractive index and Abbe number of the negative lens are N_4nAnd ν_4nAs the conditional expression:
1.45 <N_4p<1.60 (1)
60 <ν_4p<85 (2)
1.65 <N_4n<1.95 (3)
20 <ν_4n<35 (4)
To be satisfied.
With such a configuration, in particular, axial chromatic aberration can be efficiently corrected.
[0024]
A zoom lens according to a tenth aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the focal length of the entire lens system at the wide-angle end is f._WAnd the focal length of the entire lens system at the telephoto end is represented by f_TAnd the focal length of the fifth lens group is f₅As the conditional expression:
2.5 <f₅/ F_W<8.5 (5)
0.3 <f₅/ F_T<2.0 (6)
To be satisfied.
With such a configuration, in particular, light rays incident on the imaging surface can be made as close to parallel as possible, and can be efficiently received by an imaging unit using a microlens array such as a solid-state imaging device.
[0025]
A zoom lens according to an eleventh aspect of the present invention is the zoom lens according to any one of the first to third aspects, wherein the third lens group and the third lens group are associated with zooming from a wide-angle end to a telephoto end. The fourth lens group moves toward the object side such that the distance between the fourth lens groups becomes smaller.
With such a configuration, in particular, the amount of movement of the first lens group during zooming can be efficiently reduced.
A zoom lens according to a twelfth aspect of the present invention is the zoom lens according to the eleventh aspect, wherein a change amount of an interval between the first lens group and the second lens group due to zooming from a wide-angle end to a telephoto end is ZD.₁₂ZD represents the amount of change in the distance between the third lens unit and the fourth lens unit due to zooming from the wide-angle end to the telephoto end.₃₄ZD represents the amount of change in the distance between the fourth lens group and the fifth lens group due to zooming from the wide-angle end to the telephoto end.₄₅And the focal length of the entire lens system at the wide-angle end is f_WAs the conditional expression:
2.00 <ZD₁₂/ F_W<8.00 (7)
0.35 <ZD₃₄/ F_W<3.45 (8)
1.00 <ZD₄₅/ F_W<5.00 (9)
To be satisfied.
With such a configuration, it is possible to achieve good aberration correction, particularly without increasing the diameter of the front lens or the mechanism or preventing zooming.
[0026]
A zoom lens according to a thirteenth aspect of the present invention is the zoom lens according to the twelfth aspect, wherein the focal length of the entire lens system at the telephoto end is f._TAnd the focal length of the first lens group is f₁And the focal length of the second lens group is f₂As the conditional expression:
0.20 <| f₂/ F_T| <0.35 (10)
1.00 <| f₁/ F_T| <3.50 (11)
To be satisfied.
With such a configuration, it is possible to achieve an appropriate balance between enlargement of the diameter of the front lens and the mechanism and correction of aberrations.
Further, a camera according to a fourteenth aspect of the present invention uses the zoom lens according to any one of the first to twelfth aspects as a photographing optical system.
With such a configuration, in particular, it is possible to perform shooting with a high zoom ratio from a wide angle of view, and it is also possible to obtain a small, bright, and excellent image quality at the time of short-distance shooting.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a zoom lens and a camera according to the present invention will be described in detail with reference to the drawings based on embodiments according to the present invention and examples showing specific numerical examples.
The first embodiment of the present invention is an embodiment of the zoom lens according to the present invention.
First, the principle configuration of the zoom lens according to the first embodiment of the present invention will be described.
The zoom lens according to the first embodiment of the present invention includes a first lens group having a positive refractive power and a second lens group having a negative refractive power sequentially from the object side to the image plane side. , 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 further arranged as follows. It is configured in an aspect having features.
In a first aspect of the zoom lens, when the magnification is changed from the wide-angle end to the telephoto end, the first lens group to the fifth lens group operate for each lens group. The distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is reduced, so that the first lens group and the The three lens groups move toward the object side, and the fourth lens group and the fifth lens group move together to focus on a finite object (corresponding to claim 1).
[0028]
In a second aspect of the zoom lens, the fifth lens group is fixed at the time of zooming, and the first to fourth lens groups operate for each lens group at the time of zooming from the wide-angle end to the telephoto end. As the magnification changes from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases. Thus, the first lens group and the third lens group move toward the object side, respectively, and the fourth lens group and the fifth lens group move integrally to form a finite object. Focusing (corresponding to claim 2).
In a third aspect of the zoom lens, the second lens group is fixed at the time of zooming, and at the time of zooming from the wide-angle end to the telephoto end, the first lens group and the third to fifth lens groups are each lens group. Each time, the distance between the first lens group and the second lens group increases with zooming from the wide-angle end to the telephoto end, and the second lens group and the third lens group The first lens group and the third lens group move toward the object side, respectively, and the fourth lens group and the fifth lens group move integrally, so that Focus on a finite object (corresponding to claim 3).
[0029]
In a fourth aspect of the zoom lens, in the zoom lens according to any one of the first to third aspects, the fourth lens group and the fifth lens group are independently moved at the time of short-distance shooting. This focuses on an object at a finite distance (corresponding to claim 4).
According to a fifth aspect of the zoom lens, in the zoom lens according to any one of the first to third aspects, the second lens group includes a negative lens whose strongest concave surface faces the object side on the most image side. (Corresponding to claim 5).
A sixth aspect of the zoom lens is the zoom lens according to the fifth aspect, wherein the negative lens is a cemented lens (corresponding to claim 6).
A seventh aspect of the zoom lens is a zoom lens according to any one of the first to third aspects, wherein the zoom lens is disposed on the object side of the third lens group, and is integrally formed with the third lens group. The third lens group further includes an aperture stop, and the third lens group further includes, on the most object side, a positive lens having a convex surface forming an aspheric surface facing the object side (corresponding to claim 7).
[0030]
An eighth aspect of the zoom lens is the zoom lens according to any one of the first to third aspects, wherein the integrally moving lens group including the fourth lens group and the fifth lens group has two pieces. It comprises a positive lens and one negative lens (corresponding to claim 8).
A ninth aspect of the zoom lens is the zoom lens according to the eighth aspect, wherein the fourth lens group is composed of a cemented lens of a positive lens and a negative lens, and the refractive index and Abbe number of the positive lens are each N_4pAnd ν_4pAnd the refractive index and Abbe number of the negative lens are N_4nAnd ν_4nAs the conditional expression:
1.45 <N_4p<1.60 (1)
60 <ν_4p<85 (2)
1.65 <N_4n<1.95 (3)
20 <ν_4n<35 (4)
Is satisfied (corresponding to claim 9).
[0031]
A tenth aspect of the zoom lens is a zoom lens according to any one of the first to third aspects, wherein a focal length of the entire lens system at the wide-angle end is f._WAnd the focal length of the entire lens system at the telephoto end is represented by f_TAnd the focal length of the fifth lens group is f₅As the conditional expression:
2.5 <f₅/ F_W<8.5 (5)
0.3 <f₅/ F_T<2.0 (6)
Is satisfied (corresponding to claim 10).
An eleventh aspect of the zoom lens is the zoom lens according to any one of the first to third aspects, wherein the third lens group and the fourth lens group are associated with zooming from a wide-angle end to a telephoto end. The fourth lens group moves toward the object side so as to reduce the interval (corresponding to claim 11).
[0032]
According to a twelfth aspect of the zoom lens, in the zoom lens of the eleventh aspect, a change amount of an interval between the first lens group and the second lens group due to zooming from a wide-angle end to a telephoto end is represented by ZD.₁₂ZD represents the amount of change in the distance between the third lens unit and the fourth lens unit due to zooming from the wide-angle end to the telephoto end.₃₄ZD represents the amount of change in the distance between the fourth lens group and the fifth lens group due to zooming from the wide-angle end to the telephoto end.₄₅And the focal length of the entire lens system at the wide-angle end is f_WAs the conditional expression:
2.00 <ZD₁₂/ F_W<8.00 (7)
0.35 <ZD₃₄/ F_W<3.45 (8)
1.00 <ZD₄₅/ F_W<5.00 (9)
Is satisfied (corresponding to claim 12).
A thirteenth aspect of the zoom lens is the zoom lens according to the twelfth aspect, wherein the focal length of the entire lens system at the telephoto end is f_TAnd the focal length of the first lens group is f₁And the focal length of the second lens group is f₂As the conditional expression:
0.20 <| f₂/ F_T| <0.35 (10)
1.00 <| f₁/ F_T| <3.50 (11)
Is satisfied (corresponding to claim 13).
[0033]
That is, the zoom lens according to the first embodiment of the present invention has a five-group configuration of positive-negative-positive-positive-positive, and the zoom lenses of the first to third aspects are arranged from the wide-angle end. Upon zooming to the telephoto end, the first lens group and the third lens group move to the object side with zooming. The second lens group is fixed (Claim 3) or moves to the image plane side for the purpose of assisting zooming (Claims 1 and 2). The fourth lens unit functions to maintain the characteristics of the image plane during zooming, and to reduce the amount of movement of the first lens unit by acting as a zooming unit. The performance can be improved by assigning the role of correcting the image plane position and the function of maintaining the characteristics of the image plane to the fifth lens group. However, when the zoom ratio is not so large as about 5 times, This may be fixed (claim 2).
[0034]
In general, the second lens group of the zoom lens starting from a wide angle of view plays a large role mainly in correcting off-axis aberrations at the wide angle end. However, in order to achieve a large aperture ratio which is one object of the present invention, it is necessary to correct not only off-axis aberrations on the wide-angle side but also on-axis aberrations on the telephoto side in the second lens group. is there. In particular, it is difficult to correct spherical aberration on the telephoto side, and the burden on the second lens group increases. This is due to the arrangement of the first lens group and the second lens group on the telephoto side. A light ray passing through a height away from the optical axis passes through the first lens group, undergoes convex refraction, advances toward the optical axis, and enters the second lens group. At this time, the farther the first lens group and the second lens group are, that is, the lens arrangement on the telephoto side is more likely to cause a light ray passing through the first lens group and the second lens group than otherwise. The height difference becomes large, and it becomes difficult to correct spherical aberration. This characteristic becomes more remarkable as the aperture ratio increases. Therefore, by installing a negative lens with a strong concave surface facing the object side closest to the image plane side of the second lens group, it is possible to correct off-axis aberrations on the wide-angle side and on-axis aberrations on the telephoto side in a well-balanced manner. (Claim 5). Further, by joining a positive lens to the object side of the negative lens, it is possible to efficiently correct axial chromatic aberration as well as spherical aberration.
[0035]
Further, an aperture stop is provided on the object side of the third lens group, and when the aperture stop is integrated with the third lens group, the positive lens whose convex surface faces the object side is closest to the object side of the third lens group. By arranging a lens and forming this convex surface by an aspherical surface, spherical aberration can be corrected almost independently independently of other aberrations, which is desirable (claim 7). 13. The conditional expression according to claim 12, wherein the expression (7) represents the amount of change in the distance between the first lens unit and the second lens unit due to zooming from the wide-angle end to the telephoto end._wIn order to achieve a high zoom ratio below the lower limit of Expression (7), the refractive power of one or both of the first lens unit and the second lens unit becomes too strong, and the aberration It is not desirable for correction. When the value exceeds the upper limit of the expression (7), a high zoom ratio can be achieved even if the refractive power of each lens group is weak, but the diameter of the front lens becomes large and the amount of movement of the zoom lens group due to zooming becomes extremely large. This is not desirable because it causes an increase in the size of the mechanism. The refractive power ranges of the first lens unit and the second lens unit according to the expressions (10) and (11) according to the thirteenth aspect can appropriately balance the enlargement of the front lens and the mechanism and the balance of aberration correction. This is the range that can be obtained, and is more desirable.
[0036]
Expression (8) is a value relating to the amount of change in the distance between the third lens unit and the fourth lens unit due to zooming from the wide-angle end to the telephoto end, that is, this change amount is the focal length of the entire lens system at the wide-angle end. f_wIn order to bring about the effect of the image plane correction and the effect as the zooming unit by the amount of change in the distance while being less than this, either one of the third lens unit and the fourth lens unit, or both. This requires a high refractive power, which is not desirable for aberration correction. Further, if it exceeds this, the amount of movement of the group becomes large and the mechanism becomes large, which is not desirable.
Equation (9) calculates the amount of change in the distance between the fourth lens group and the fifth lens group due to zooming from the wide-angle end to the telephoto end by the focal length f._wIf the value is less than this, the variable power operation of the fourth lens unit is hindered, and therefore, it is not desirable. Further, if it exceeds this, the amount of movement of the group becomes large, and the mechanism becomes large.
[0037]
The zoom lens according to the present invention is mainly intended to be used for a camera using solid-state electronic imaging means such as a digital camera and a digital video camera. Therefore, due to the characteristics of an electronic imaging device having a microlens array, such as a solid-state imaging device such as a CCD (Charge Coupled Device), it is more efficient for the imaging device to receive light rays incident on the imaging surface as parallel as possible. can do. The expressions (5) and (6) in claim 10 are conditional expressions for achieving this. If the conditional expression is not satisfied, the power of the fifth lens unit becomes too strong. Is too weak, and the light incident on the imaging surface is too angled, which is not desirable.
Further, in the zoom lens according to the present invention, the fourth lens group and the fifth lens group are integrally moved for the purpose of maintaining good lens performance during short-distance shooting. Originally, it is desirable to use a light lens group having a small number of lenses as the focus group in the inner focus type lens system in order to enable quick autofocus operation. However, in order to obtain good performance at the time of close-up shooting, a plurality of lenses are necessarily required for the focus group, which is inconsistent with the object of the present invention of obtaining high performance with a small number of lenses.
[0038]
Therefore, the zoom lens according to the present invention obtains high performance even at the time of short-distance shooting by moving the fourth lens unit and the fifth lens unit together during focusing while moving them together during focusing. (Claim 1, claim 2, claim 3). Further, the focus group in which the fourth lens group and the fifth lens group are integrated has a so-called triplet type configuration in which the inside is composed of two positive lenses and one negative lens, so that even a small number of lenses are provided. Good performance can be obtained efficiently (claim 8). Further, when photographing at a shorter distance, the fourth lens group and the fifth lens group can be independently moved to compensate for a change in the characteristic of the image plane due to the inner focus. Performance can be obtained (claim 4). At this time, if the fourth lens group is a cemented lens of a positive lens and a negative lens and the conditional expressions (1) to (4) can be satisfied, axial chromatic aberration can be efficiently corrected. Therefore, it is more desirable (claim 9).
Next, a principle configuration of a camera (not shown) according to a second embodiment of the present invention will be described.
The camera according to the second embodiment of the present invention includes the above-described zoom lens as a photographing optical system (corresponding to claim 14). A camera equipped with such a zoom lens as a photographing optical system has a sufficiently small size and a wide angle of view by suppressing aberration fluctuation due to zooming in the zoom lens, reducing each aberration, and achieving high resolution. While achieving a high-performance shooting optical system.
[0039]
【Example】
Next, several examples showing specific numerical configurations of the zoom lens according to the first embodiment of the present invention will be described in detail.
Specific examples and numerical examples of the zoom lens according to the first embodiment of the present invention will be described below. In each embodiment, the aberration of the zoom lens is sufficiently corrected, and it is possible to correspond to a light receiving element having 3 to 5 million pixels. By configuring the zoom lens as in the first embodiment, it is possible to secure a very good image performance while achieving a sufficiently wide angle of view and a high zoom ratio. It will be more obvious.
In the description related to each of the following embodiments, the following various symbols are used.
[0040]
f: focal length of the whole system
F: F number
ω: Half angle of view
R: radius of curvature
D: Surface spacing
N_d: Refractive index
ν_d: Abbe number
K: aspherical conical constant
A₄: 4th order aspheric coefficient
A₆: 6th order aspheric coefficient
A₈: 8th order aspheric coefficient
A₁₀: 10th order aspheric coefficient
However, the aspheric surface used here is defined by the following equation, where C is the reciprocal of the paraxial curvature radius (paraxial curvature) and H is the height from the optical axis.
[0041]
(Equation 1)

[0042]
[First embodiment]
FIG. 1 shows a configuration of an optical system of a zoom lens according to a first embodiment of the present invention.
The zoom lens shown in FIG. 1 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the seventh lens E7 constitute a second lens group G2, and the eighth lens E8 to the tenth lens E10. The lens E10 forms a third lens group G3, the eleventh lens E11 and the twelfth lens E12 form a fourth lens group G4, and the thirteenth lens E13 forms a fifth lens group G5. Each of the lens groups is supported by an appropriate common support frame or the like, and operates integrally with each lens group during zooming or the like. FIG. 1 also shows a part of the surface number of each optical surface for reference. 1 are used independently for each embodiment in order to avoid complication of the description due to an increase in the number of digits of the reference code. The configuration is not necessarily the same as the embodiment.
[0043]
1, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and the like are sequentially arranged from the object side of the subject or the like to the image plane side. A seventh lens E7, an aperture FA, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, and an optical filter OF. An image is formed behind an optical filter OF having various optical filtering functions.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive lens formed of a biconvex lens, and the third lens E3 is a positive meniscus lens formed on the object side. The first lens E1 and the second lens E2 are two cemented lenses that are tightly cemented, and the first lens group G1 including the first lens E1 to the third lens E3 is positive as a whole. Present focal length. The fourth lens E4 is a negative lens formed of a biconcave lens, the fifth lens E5 is a negative meniscus lens formed convex on the image plane side, the sixth lens E6 is a positive lens formed of a biconvex lens, and the seventh lens E7 Is a negative lens composed of a biconcave lens, and the second lens group G2 constituted by the fourth lens E4 to the seventh lens E7 has a negative focal length as a whole.
[0044]
The eighth lens E8 is a positive lens formed of a biconvex lens, the ninth lens E9 is a positive meniscus lens formed convex on the object side, and the tenth lens E10 is a negative meniscus lens formed convex on the object side. In addition, the third lens group G3 including the eighth lens E8 to the tenth lens E10 has a positive focal length as a whole. The eleventh lens E11 is a positive lens composed of a biconvex lens, the twelfth lens E12 is a negative meniscus lens convexly formed on the image plane side, and the eleventh lens E11 and the twelfth lens E12 are tightly joined. The fourth lens group G4 composed of the eleventh lens E11 and the twelfth lens E12 has a positive focal length as a whole. The thirteenth lens E13 is a positive lens formed of a biconvex lens, and only the thirteenth lens E13 forms a fifth lens group G5 having a positive focal length. The aperture stop FA disposed between the second lens group G2 and the third lens group G3 is integrally supported by the third lens group G3 with a constant distance between the third lens group G3. The optical filter OF disposed on the image plane side of the thirteenth lens E13, which is the fifth lens group G5, includes a cover glass of a solid-state imaging device as necessary, has various optical filtering functions, and It is held integrally with the image sensor.
[0045]
The sixth surface, which is the object-side surface of the fourth lens E4 located closest to the object side of the second lens group G2, and the object-side surface of the fifth lens E5 located second from the object side of the second lens group G2. The eighth surface, the fifteenth surface which is the object-side surface of the eighth lens E8 located closest to the object side of the third lens group G3, and the object-side surface of the thirteenth lens E13 constituting the fifth lens group G5. The twenty-fourth surfaces, which are surfaces, are each aspheric.
In the first embodiment, the focal length f, the F-number F, and the half angle of view ω of the entire system are f = 5.8 to 41.0 and F = 2.55 to 3.16 due to zooming, respectively. , Ω = 39.02 to 6.08. The optical characteristics associated with each optical surface and optical element are as follows.
[0046]
[Table 1]
optical properties

[0047]
In Table 1, each of the sixth, eighth, fifteenth, and twenty-fourth optical surfaces described as “(aspherical surface)” is an aspherical surface. Such parameters are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 2.04653 × 10^-4
A₆= -1.64914 × 10^-6
A₈= 9.76489 × 10^-9
A₁₀= −2.02952 × 10^-11
Aspheric surface: 8th surface
K = 0
A₄= −6.87829 × 10^-5
A₆= −9.50657 × 10^-7
A₈= 3.60236 × 10^-8
A₁₀= −6.707740 × 10^-10
[0048]
Aspheric surface: 15th surface
K = 0
A₄= −5.589999 × 10^-5
A₆= −3.80367 × 10^-8
A₈= −5.153396 × 10^-10
A₁₀= −5.45902 × 10^-12
Aspheric surface: 24th surface
K = 0
A₄= −5.08398 × 10^-5
A₆= 1.443379 × 10^-7
A₈= −6.5549 × 10^-9
A₁₀= 6.34852 × 10^-11
[0049]
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second lens group G2 and the diaphragm FA_Thirteen, The distance D between the third lens group G3 and the fourth lens group G4₂₀, The distance D between the fourth lens group G4 and the fifth lens group G5₂₃And the distance D between the fifth lens group G5 and the optical filter OF₂₅Are variable, and these variable intervals D₅, D_Thirteen, D₂₀, D₂₃, D₂₅Is changed as shown in the following table with zooming.
[0050]
[Table 2]
Variable interval

[0051]
The third-order aberration coefficient values of the first embodiment for objects at infinity and near objects in the intermediate range are as shown in Tables 3 and 4, respectively. However, each symbol in the table represents the following, respectively.
SA: spherical aberration coefficient
CM: Comatic aberration coefficient
AS: Astigmatism coefficient
DST: Distortion aberration coefficient
LPF: Low pass filter
[0052]
[Table 3]
Object at infinity

[0053]
[Table 4]
0.5m short-range object

[0054]
According to these aberration coefficients, although the aberration variation is very small even though the conjugate length is approaching a short distance of 0.5 m, the focusing method according to this embodiment of the present invention is excellent. I understand.
[0055]
[Second embodiment]
FIG. 2 shows a configuration of an optical system of a zoom lens according to a second embodiment of the present invention.
The zoom lens shown in FIG. 2 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the seventh lens E7 constitute a second lens group G2, and the eighth lens E8 to the tenth lens E10. The lens E10 forms a third lens group G3, the eleventh lens E11 and the twelfth lens E12 form a fourth lens group G4, and the thirteenth lens E13 forms a fifth lens group G5. Each of the lens groups is supported by an appropriate common support frame or the like, and operates integrally with each lens group during zooming or the like. FIG. 2 also shows the surface number of each optical surface for reference. Note that, as described above, each reference numeral for FIG. 2 is used independently for each embodiment, and even if a common reference numeral is assigned, it does not necessarily have a common configuration with other embodiments.
[0056]
In FIG. 2, for example, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and the like in order from the object side of the subject or the like to the image plane side. A seventh lens E7, an aperture FA, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, and an optical filter OF. An image is formed behind an optical filter OF having various optical filtering functions.
[0057]
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive lens formed of a biconvex lens, and the third lens E3 is a positive meniscus lens formed on the object side. The first lens E1 and the second lens E2 are two cemented lenses that are tightly cemented, and the first lens group G1 including the first lens E1 to the third lens E3 is positive as a whole. Present focal length. The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, the sixth lens E6 is a positive lens composed of a biconvex lens, and the seventh lens E7 is located on the image plane side. The sixth lens E6 and the seventh lens E7 are convexly formed negative meniscus lenses, and the sixth lens E6 and the seventh lens E7 are two cemented lenses that are tightly cemented, and the second lens E4 is configured by the fourth lens E4 to the seventh lens E7. The lens group G2 exhibits a negative focal length as a whole.
[0058]
The eighth lens E8 is a positive lens formed of a biconvex lens, the ninth lens E9 is also a positive lens formed of a biconvex lens, and the tenth lens E10 is a negative meniscus lens formed convex on the object side. The third lens group G3 composed of the eighth lens E8 to the tenth lens E10 has a positive focal length as a whole. The eleventh lens E11 is a positive lens composed of a biconvex lens, the twelfth lens E12 is a negative meniscus lens convexly formed on the image plane side, and the eleventh lens E11 and the twelfth lens E12 are tightly joined. The fourth lens group G4 composed of the eleventh lens E11 and the twelfth lens E12 has a positive focal length as a whole. The thirteenth lens E13 is a positive lens formed of a biconvex lens, and only the thirteenth lens E13 forms a fifth lens group G5 having a positive focal length. The aperture stop FA disposed between the second lens group G2 and the third lens group G3 is integrally supported by the third lens group G3 with a constant distance between the third lens group G3. The optical filter OF disposed on the image plane side of the thirteenth lens E13, which is the fifth lens group G5, includes a cover glass of a solid-state imaging device as necessary, has various optical filtering functions, and It is held integrally with the image sensor.
[0059]
The sixth surface, which is the object-side surface of the fourth lens E4 located closest to the object side of the second lens group G2, and the object-side surface of the fifth lens E5 located second from the object side of the second lens group G2. The eighth surface, the fourteenth surface which is the object-side surface of the eighth lens E8 located closest to the object side of the third lens group G3, and the object-side surface of the thirteenth lens E13 constituting the fifth lens group G5. The 23rd surface, which is a surface, is an aspheric surface.
In the second embodiment, the focal length f, the F-number F, and the half angle of view ω of the entire system are f = 5.8 to 28.8 and F = 2.16 to 3.00, respectively, due to zooming. , Ω = 38.94 to 8.56. The optical characteristics associated with each optical surface and optical element are as follows.
[0060]
[Table 5]
optical properties

[0061]
In Table 5, the sixth, eighth, fourteenth, and twenty-third optical surfaces described as “(aspheric surface)” are aspherical surfaces. Such parameters are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 1.91160 × 10^-4
A₆= -1.69695 * 10^-6
A₈= 1.10809 × 10^-8
A₁₀= −3.06549 × 10^-11
Aspheric surface: 8th surface
K = 0
A₄= −5.535313 × 10^-5
A₆= 4.10949 × 10^-7
A₈= -3.555104 × 10^-9
A₁₀= −1.1518 × 10^-10
[0062]
Aspheric surface: 14th surface
K = 0
A₄= −7.06765 × 10^-5
A₆= −9.84275 × 10^-8
A₈= 4.53633 × 10^-10
A₁₀= −1.09608 × 10^-10
Aspheric surface: 23rd surface
K = 0
A₄= −3.771712 × 10^-5
A₆= 4.4288 × 10^-9
A₈= -3.16773 × 10^-9
A₁₀= 2.76404 × 10^-11
[0063]
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second lens group G2 and the diaphragm FA₁₂, The distance D between the third lens group G3 and the fourth lens group G4₁₉And the distance D between the fourth lens group G4 and the fifth lens group G5.₂₂, Are variable and these variable intervals D₅, D₁₂, D₁₉, D₂₂Is changed as shown in the following table with zooming. In this case, the distance between the fifth lens group G5 and the optical filter OF is fixed (claim 2).
[0064]
[Table 6]
Variable interval

[0065]
[Third embodiment]
FIG. 3 shows a configuration of an optical system of a zoom lens according to a third embodiment of the present invention.
The zoom lens shown in FIG. 3 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the seventh lens E7 constitute a second lens group G2, and the eighth lens E8 to the tenth lens E10. The lens E10 forms a third lens group G3, the eleventh lens E11 and the twelfth lens E12 form a fourth lens group G4, and the thirteenth lens E13 forms a fifth lens group G5. Each lens group is supported by an appropriate common support frame or the like, and operates integrally for each lens group during zooming or the like. FIG. 3 also shows the surface number of each optical surface for reference.
Note that, as described above, each reference numeral for FIG. 3 is used independently for each embodiment, and even if a common reference numeral is assigned, it is not necessarily a common configuration in other embodiments.
[0066]
In FIG. 3, for example, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, and the like in order from the object side of the subject or the like to the image plane side. A seventh lens E7, an aperture FA, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, and an optical filter OF. An image is formed behind an optical filter OF having various optical filtering functions.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive lens formed of a biconvex lens, and the third lens E3 is a positive meniscus lens formed on the object side. The first lens E1 and the second lens E2 are two cemented lenses that are tightly cemented, and the first lens group G1 including the first lens E1 to the third lens E3 is positive as a whole. Present focal length.
[0067]
The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, the sixth lens E6 is a positive lens composed of a biconvex lens, and the seventh lens E7 is a biconcave lens. The sixth lens E6 and the seventh lens E7 are negative cemented lenses, and are closely cemented two cemented lenses. The second lens group G2 constituted by the fourth lens E4 to the seventh lens E7 is As a negative focal length. The eighth lens E8 is a positive lens formed of a biconvex lens, the ninth lens E9 is also a positive lens formed of a biconvex lens, and the tenth lens E10 is a negative meniscus lens formed convex on the object side. The third lens group G3 composed of the eighth lens E8 to the tenth lens E10 has a positive focal length as a whole. The eleventh lens E11 is a positive lens composed of a biconvex lens, the twelfth lens E12 is a negative meniscus lens convexly formed on the image plane side, and the eleventh lens E11 and the twelfth lens E12 are tightly joined. The fourth lens group G4 composed of the eleventh lens E11 and the twelfth lens E12 has a positive focal length as a whole.
[0068]
The thirteenth lens E13 is a positive lens formed of a biconvex lens, and only the thirteenth lens E13 forms a fifth lens group G5 having a positive focal length. The aperture stop FA disposed between the second lens group G2 and the third lens group G3 is integrally supported by the third lens group G3 with a constant distance between the third lens group G3. The optical filter OF disposed on the image plane side of the thirteenth lens E13, which is the fifth lens group G5, includes a cover glass of a solid-state imaging device as necessary, has various optical filtering functions, and It is held integrally with the image sensor.
The sixth surface, which is the object-side surface of the fourth lens E4 located closest to the object side of the second lens group G2, and the object-side surface of the fifth lens E5 located second from the object side of the second lens group G2. The eighth surface, the fourteenth surface which is the object-side surface of the eighth lens E8 located closest to the object side of the third lens group G3, and the object-side surface of the thirteenth lens E13 constituting the fifth lens group G5. The 23rd surface, which is a surface, is an aspheric surface.
In the third embodiment, the focal length f, the F-number F, and the half angle of view ω of the entire system are f = 5.8 to 28.8 and F = 2.13 to 3.10. , Ω = 38.92 to 8.55. The optical characteristics associated with each optical surface and optical element are as follows.
[0069]
[Table 7]
optical properties

[0070]
In Table 7, each of the sixth, eighth, fourteenth, and twenty-third optical surfaces described as “(aspheric surface)” is an aspheric surface. Such parameters are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 1.75808 × 10^-4
A₆= −1.53415 × 10^-6
A₈= 1.01590 × 10^-8
A₁₀= −2.668790 × 10^-11
Aspheric surface: 8th surface
K = 0
A₄= −6.93531 × 10^-5
A₆= 7.38335 × 10^-7
A₈= −1.53184 × 10^-8
A₁₀= −5.448678 × 10^-11
[0071]
Aspheric surface: 14th surface
K = 0
A₄= −7.23944 × 10^-5
A₆= −2.06772 × 10^-7
A₈= 1.06743 × 10^-9
A₁₀= −1.6845 × 10^-10
Aspheric surface: 23rd surface
K = 0
A₄= −3.942285 × 10^-5
A₆= 8.69223 × 10^-8
A₈= −4.886365 × 10^-9
A₁₀= 4.61997 × 10^-11
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second lens group G2 and the diaphragm FA₁₂, The distance D between the third lens group G3 and the fourth lens group G4₁₉, The distance D between the fourth lens group G4 and the fifth lens group G5₂₂And the distance D between the fifth lens group G5 and the optical filter OF₂₄Are variable, and these variable intervals D₅, D₁₂, D₁₉, D₂₂, D₂₄Is changed as shown in the following table with zooming.
[0072]
[Table 8]
Variable interval

[0073]
[Fourth embodiment]
FIG. 4 shows a configuration of an optical system of a zoom lens according to a fourth embodiment of the present invention.
The zoom lens shown in FIG. 4 includes a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, and a ninth lens. A lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, an aperture FA, and an optical filter OF are provided. In this case, the first lens E1 to the third lens E3 constitute a first lens group G1, the fourth lens E4 to the seventh lens E7 constitute a second lens group G2, and the eighth lens E8 to the tenth lens E10. The lens E10 forms a third lens group G3, the eleventh lens E11 and the twelfth lens E12 form a fourth lens group G4, and the thirteenth lens E13 forms a fifth lens group G5. Each lens group is supported by an appropriate common support frame or the like, and operates integrally for each lens group during zooming or the like. FIG. 4 also shows the surface number of each optical surface for reference.
Note that, as described above, each reference numeral for FIG. 4 is independently used for each embodiment, and even if a common reference numeral is assigned, it is not necessarily a common configuration in other embodiments.
[0074]
In FIG. 4, for example, in order from the object side such as a subject or the like to the image plane side, 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 aperture FA, an eighth lens E8, a ninth lens E9, a tenth lens E10, an eleventh lens E11, a twelfth lens E12, a thirteenth lens E13, and an optical filter OF. An image is formed behind an optical filter OF having various optical filtering functions.
The first lens E1 is a negative meniscus lens formed convex on the object side, the second lens E2 is a positive meniscus lens formed convex on the object side, and the third lens E3 is formed convex on the object side. The first lens E1 and the second lens E2 are tightly cemented two cemented lenses, and the first lens group G1 including the first lens E1 to the third lens E3 is Have a positive focal length as a whole. The fourth lens E4 is a negative lens composed of a biconcave lens, the fifth lens E5 is also a negative lens composed of a biconcave lens, the sixth lens E6 is a positive lens composed of a biconvex lens, and the seventh lens E7 is located on the image plane side. The sixth lens E6 and the seventh lens E7 are convexly formed negative meniscus lenses, and the sixth lens E6 and the seventh lens E7 are two cemented lenses that are tightly cemented, and the second lens E4 is configured by the fourth lens E4 to the seventh lens E7. The lens group G2 exhibits a negative focal length as a whole.
[0075]
The eighth lens E8 is a positive meniscus lens formed convex on the object side, the ninth lens E9 is also a positive meniscus lens formed convex on the object side, and the tenth lens E10 is formed convex on the object side. The third lens group G3 constituted by the eighth lens E8 to the tenth lens E10 has a positive focal length as a whole. The eleventh lens E11 is a positive lens composed of a biconvex lens, the twelfth lens E12 is a negative meniscus lens convexly formed on the image plane side, and the eleventh lens E11 and the twelfth lens E12 are tightly joined. The fourth lens group G4 composed of the eleventh lens E11 and the twelfth lens E12 has a positive focal length as a whole. The thirteenth lens E13 is a positive meniscus lens formed convex on the object side, and only the thirteenth lens E13 constitutes a fifth lens group G5 having a positive focal length. The aperture stop FA disposed between the second lens group G2 and the third lens group G3 is integrally supported by the third lens group G3 with a constant distance between the third lens group G3. The optical filter OF disposed on the image plane side of the thirteenth lens E13, which is the fifth lens group G5, includes a cover glass of a solid-state imaging device as necessary, has various optical filtering functions, and It is held integrally with the image sensor.
[0076]
The sixth surface, which is the object-side surface of the fourth lens E4 located closest to the object side of the second lens group G2, and the object-side surface of the fifth lens E5 located second from the object side of the second lens group G2. The eighth surface, the fourteenth surface which is the object-side surface of the eighth lens E8 located closest to the object side of the third lens group G3, and the object-side surface of the thirteenth lens E13 constituting the fifth lens group G5. The 23rd surface, which is a surface, is an aspheric surface.
In the fourth embodiment, the focal length f, the F-number F, and the half angle of view ω of the entire system are f = 5.8 to 41.0 and F = 2.56 to 3.62, respectively, due to zooming. , Ω = 39.86 to 6.36. The optical characteristics associated with each optical surface and optical element are as follows.
[0077]
[Table 9]
optical properties

[0078]
In Table 9, the sixth, eighth, fourteenth, and twenty-third optical surfaces described as “(aspherical surface)” are aspherical surfaces. Such parameters are as follows.
Aspheric surface: 6th surface
K = 0
A₄= 1.55611 × 10^-4
A₆= -1.13073 × 10^-6
A₈= 5.38045 × 10^-9
A₁₀= -1.3333 × 10^-11
Aspheric surface: 8th surface
K = 0
A₄= −4.47372 × 10^-5
A₆= -1.50692 × 10^-7
A₈= 1.08923 × 10^-8
A₁₀= 5.17998 × 10^-12
[0079]
Aspheric surface: 14th surface
K = 0
A₄= −6.18552 × 10^-5
A₆= −2.1125 × 10^-7
A₈= 1.83234 × 10^-9
A₁₀= −4.82639 × 10^-11
Aspheric surface: 23rd surface
K = 0
A₄= −6.27922 × 10^-5
A₆= −4.4157 × 10^-8
A₈= −1.80708 × 10^-9
A₁₀= 1.35096 × 10^-11
Distance D between first lens group G1 and second lens group G2₅, The distance D between the second lens group G2 and the diaphragm FA₁₂, The distance D between the third lens group G3 and the fourth lens group G4₁₉, The distance D between the fourth lens group G4 and the fifth lens group G5₂₂And the distance D between the fifth lens group G5 and the optical filter OF₂₄Are variable, and these variable intervals D₅, D₁₂, D₁₉, D₂₂, D₂₄Is changed as shown in the following table with zooming.
[0080]
[Table 10]
Variable interval

[0081]
The focal length f of the first lens group to the fifth lens group in the first to fourth embodiments described above.₁~ F₅, The focal length f of the entire lens system at the wide-angle end_w, The focal length f of the entire lens system at the telephoto end_TAre as shown in Table 11 below.
[0082]
[Table 11]

[0083]
The numerical values relating to the above-described conditional expressions (1) to (11) of the present invention in the first to fourth embodiments of the present invention are as shown in Tables 12 and 13 below. The embodiment satisfies each conditional expression.
[0084]
[Table 12]

[0085]
[Table 13]

[0086]
FIG. 5 is an aberration curve diagram at the short focal length end of the zoom lens of the first embodiment, FIG. 6 is an aberration curve diagram at an intermediate focal length of the zoom lens of the first embodiment, and FIG. FIG. 3 is an aberration curve diagram at a long focal end of the zoom lens according to the first embodiment. FIG. 8 is an aberration curve diagram at the short focal length end of the zoom lens of the second embodiment, FIG. 9 is an aberration curve diagram at an intermediate focal length of the zoom lens of the second embodiment, and FIG. FIG. 8 is an aberration curve diagram at the long focal end of the zoom lens according to Example 2; Similarly, FIG. 11 is an aberration curve diagram at the short focal length end of the zoom lens of the third embodiment, FIG. 12 is an aberration curve diagram at an intermediate focal length of the zoom lens of the third embodiment, and FIG. FIG. 10 is an aberration curve diagram at the long focal end of the zoom lens according to Example 3; FIG. 14 is an aberration curve diagram at the short focal length end of the zoom lens of the fourth embodiment, FIG. 15 is an aberration curve diagram at an intermediate focal length of the zoom lens of the fourth embodiment, and FIG. FIG. 5 is an aberration curve diagram at a long focal end of the zoom lens according to the example. In the aberration curve diagrams of FIGS. 5 to 16, the broken line in the spherical aberration diagram represents a sine condition, the solid line in the astigmatism diagram represents sagittal, and the broken line represents meridional. From these aberration curve diagrams, it can be seen that good characteristics are obtained by the above-described embodiments.
If a camera is configured using the zoom lens described in each of the embodiments as a photographing lens, it is possible to realize a camera that is small in size and has a wide angle of view and high image quality.
[0087]
【The invention's effect】
As described above, according to the present invention, it is possible to achieve high zooming from a wide angle of view, and at the same time, it is possible to obtain a zoom lens and a compact zoom lens that are compact, bright, and that can obtain excellent lens performance at the time of close-up shooting. Thus, a camera having a wide angle of view and high image quality can be provided.
That is, according to the zoom lens of claim 1 of the present invention, from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, and the second 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, the first lens group is used when zooming from a wide-angle end to a telephoto end. The fifth to fifth lens groups operate for each lens group, and as the magnification changes from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and The first lens group and the third lens group move toward the object side, respectively, such that the distance between the lens group and the third lens group decreases, and the fourth lens group and the fifth lens group move. Is moved by moving By focusing on distant objects, high zooming from a wide angle of view is possible, and at the same time, it is compact and bright, and it is also possible to obtain excellent lens performance at short distance shooting, especially with a small number of lenses. High performance can be obtained, and high performance can be obtained even at the time of close-up shooting.
[0088]
According to the zoom lens of the second 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 second lens group having a positive refractive power are sequentially arranged from the object side. 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, the fifth lens group is fixed at the time of zooming, and is telephoto from the wide-angle end. At the time of zooming to the end, the first lens group to the fourth lens group operate for each lens group, and the first lens group and the second lens are changed with zooming from the wide-angle end to the telephoto end. The first lens group and the third lens group move toward the object side such that the distance between the groups increases and the distance between the second lens group and the third lens group decreases. Together with the fourth lens group and the fifth lens group By focusing on an object at a finite distance by moving it integrally, it is possible to obtain a high performance with a small number of lenses and a high performance even at the time of short-distance shooting, particularly with a configuration different from the first aspect. It becomes possible.
[0089]
According to the zoom lens of the third aspect of the present invention, from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens having a positive refractive power. In a zoom lens comprising a lens group, a fourth lens group having a positive refractive power, and a fifth lens group having a positive refractive power, the second lens group is fixed at the time of zooming and moves from the wide-angle end to the telephoto end. When the magnification is changed, the first lens group and the third to fifth lens groups operate for each lens group, and as the magnification is changed from the wide-angle end to the telephoto end, the first lens group and the third lens group are moved. The first lens group and the third lens group are moved toward the object side such that the distance between the two lens groups is increased and the distance between the second lens group and the third lens group is reduced. The fourth lens group and the fifth lens By focusing the object at a finite distance by moving the group as a unit, high performance can be obtained with a small number of lenses, especially when shooting at close distances, with a configuration different from the first and second aspects. High performance can be obtained.
[0090]
According to the zoom lens of the fourth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the fourth lens group and the fifth lens group are arranged at the time of short-range shooting. Focusing on objects at finite distances by independently moving each other enables compensation for changes in image plane characteristics due to inner focus, especially when shooting at closer distances, to obtain better performance. Becomes possible.
According to the zoom lens of the fifth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the second lens group has a strong concave surface on the most image side. Including a negative lens directed toward the side makes it possible to correct off-axis aberrations on the wide-angle side and on-axis aberrations on the telephoto side in a well-balanced manner.
[0091]
According to the zoom lens of claim 6 of the present invention, in the zoom lens of claim 5, since the negative lens is a cemented lens, it is possible to efficiently correct not only spherical aberration but also axial chromatic aberration. It becomes.
According to the zoom lens of the seventh aspect of the present invention, in the zoom lens of any one of the first to third aspects, the zoom lens is disposed on the object side of the third lens group. The third lens group further includes an integral aperture stop, and the third lens group further includes a positive lens having a convex surface forming an aspheric surface facing the object side on the most object side, thereby reducing spherical aberration. Apart from other aberrations, it is possible to correct almost independently.
According to the zoom lens of the eighth aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the lens that moves as a unit, the lens being composed of the fourth lens group and the fifth lens group. Since the group is composed of two positive lenses and one negative lens, particularly, good performance can be efficiently obtained even with a small number of lenses.
[0092]
According to a ninth aspect of the present invention, in the zoom lens of the eighth aspect, the fourth lens group includes a cemented lens of a positive lens and a negative lens, and has a refractive index and an Abbe number of the positive lens. To N_4pAnd ν_4pAnd the refractive index and Abbe number of the negative lens are N_4nAnd ν_4nAs the conditional expression:
1.45 <N_4p<1.60
60 <ν_4p<85
1.65 <N_4n<1.95
20 <ν_4n<35
In particular, it is possible to efficiently correct axial chromatic aberration.
[0093]
According to the zoom lens of the tenth aspect of the present invention, in the zoom lens of any one of the first to third aspects, the focal length of the entire lens system at the wide-angle end is f._WAnd the focal length of the entire lens system at the telephoto end is represented by f_TAnd the focal length of the fifth lens group is f₅As the conditional expression:
2.5 <f₅/ F_W<8.5
0.3 <f₅/ F_T<2.0
In particular, by satisfying the above condition, it becomes possible to make the light rays incident on the image forming surface as close to parallel as possible, and to efficiently receive the light by the imaging means using a microlens array such as a solid-state imaging device.
According to a zoom lens of an eleventh aspect of the present invention, in the zoom lens according to any one of the first to third aspects, the third lens group is associated with zooming from a wide-angle end to a telephoto end. By moving the fourth lens group toward the object side so that the distance between the first lens group and the fourth lens group becomes smaller, it is possible to efficiently reduce the amount of movement of the first lens group particularly during zooming. It becomes.
[0094]
According to the zoom lens of the twelfth aspect of the present invention, in the zoom lens of the eleventh aspect, the amount of change in the distance between the first lens group and the second lens group due to zooming from the wide-angle end to the telephoto end is determined. ZD₁₂ZD represents the amount of change in the distance between the third lens unit and the fourth lens unit due to zooming from the wide-angle end to the telephoto end.₃₄ZD represents the amount of change in the distance between the fourth lens group and the fifth lens group due to zooming from the wide-angle end to the telephoto end.₄₅And the focal length of the entire lens system at the wide-angle end is f_WAs the conditional expression:
2.00 <ZD₁₂/ F_W<8.00
0.35 <ZD₃₄/ F_W<3.45
1.00 <ZD₄₅/ F_W<5.00
In particular, satisfactory aberration correction can be achieved without increasing the diameter of the front lens or the mechanism or hindering zooming.
[0095]
According to the zoom lens of the present invention, the focal length of the entire lens system at the telephoto end is set to f._TAnd the focal length of the first lens group is f₁And the focal length of the second lens group is f₂As the conditional expression:
0.20 <| f₂/ F_T| <0.35
1.00 <| f₁/ F_T| <3.50
In particular, it is possible to achieve an appropriate balance between enlargement of the front lens diameter and the mechanism and aberration correction.
Further, according to the camera of the fourteenth aspect of the present invention, the zoom lens according to any one of the first to twelfth aspects is used as an optical system for photographing, so that a wide image is obtained. In addition to being able to perform high-magnification zooming from a corner, it is also possible to obtain a small, bright, and excellent image quality in short-distance shooting.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a configuration of an optical system of a first example of a zoom lens according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a configuration of an optical system of a second example of the zoom lens according to the first embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating a configuration of an optical system of a third example of the zoom lens according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram illustrating a configuration of an optical system of a fourth example of the zoom lens according to the first embodiment of the present invention.
FIG. 5 is an aberration curve diagram showing aberration characteristics at the short focal length end of the optical system of the first example shown in FIG. 1 of the zoom lens according to the first embodiment of the present invention.
6 is an aberration curve diagram showing aberration characteristics of the optical system of the first example shown in FIG. 1 at an intermediate focal length of the zoom lens according to the first embodiment of the present invention.
FIG. 7 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system according to the first example shown in FIG.
8 is an aberration curve diagram showing aberration characteristics at the short focal length end of the optical system according to the second example shown in FIG. 2 of the zoom lens according to the first embodiment of the present invention.
9 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at an intermediate focal length of the optical system according to the second example shown in FIG. 2. FIG.
FIG. 10 is an aberration curve diagram showing aberration characteristics of the zoom lens according to the first embodiment of the present invention at the long focal end of the optical system according to the second example shown in FIG. 2;
11 is an aberration curve diagram showing an aberration characteristic of the zoom lens according to the first embodiment of the present invention at the short focal length end of the optical system of Example 3 shown in FIG. 3;
12 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 3 shown in FIG. 3 of the zoom lens according to the first embodiment of the present invention.
13 is an aberration curve diagram showing an aberration characteristic at a long focal end of the optical system according to Example 3 shown in FIG. 3 of the zoom lens according to the first embodiment of the present invention.
14 is an aberration curve diagram showing an aberration characteristic at a short focal length end of the optical system of Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
15 is an aberration curve diagram showing an aberration characteristic at an intermediate focal length of the optical system of Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
16 is an aberration curve diagram showing an aberration characteristic at a long focal end of an optical system according to Example 4 shown in FIG. 4 of the zoom lens according to the first embodiment of the present invention.
[Explanation of symbols]
G1 First lens group
G2 Second lens group
G3 Third lens group
G4 4th lens group
FA aperture
OF optical filter
E1 First lens
E2 Second lens
E3 Third lens
E4 4th lens
E5 Fifth lens
E6 6th lens
E7 7th lens
E8 8th lens
E9 9th lens
E10 10th lens
E11 eleventh lens
E12 12th lens
E13 thirteenth lens

Claims (14)

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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
At the time of zooming from the wide-angle end to the telephoto end, the first lens group to the fifth lens group operate for each lens group, and with the zooming from the wide-angle end to the telephoto end, the first lens group and the fifth lens group are moved. The first lens group and the third lens group are respectively directed toward the object side such that the distance between the second lens group is increased and the distance between the second lens group and the third lens group is reduced. Move and
A zoom lens, wherein an object at a finite distance is focused by moving the fourth lens group and the fifth lens group integrally. 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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
The fifth lens group is fixed at the time of zooming, and at the time of zooming from the wide-angle end to the telephoto end, the first to fourth lens groups operate for each lens group to move from the wide-angle end to the telephoto end. The first lens is set such that the distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases as the magnification changes. The group and the third lens group move toward the object side, respectively.
A zoom lens, wherein an object at a finite distance is focused by moving the fourth lens group and the fifth lens group integrally. 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, a fourth lens group having a positive refractive power, and In a zoom lens including a fifth lens group having a positive refractive power,
The second lens group is fixed at the time of zooming, and at the time of zooming from the wide-angle end to the telephoto end, the first lens group and the third to fifth lens groups operate for each lens group, and from the wide-angle end. With zooming to the telephoto end, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is reduced. The first lens group and the third lens group move toward the object side, respectively,
A zoom lens, wherein an object at a finite distance is focused by moving the fourth lens group and the fifth lens group integrally. 4. The camera according to claim 1, wherein at the time of close-up shooting, the fourth lens group and the fifth lens group are independently moved to focus on a finite object. 5. Item 2. The zoom lens according to item 1. The zoom lens according to any one of claims 1 to 3, wherein the second lens group includes a negative lens having a strong concave surface facing the object side on the most image plane side. . The zoom lens according to claim 5, wherein the negative lens is a cemented lens. A convex surface disposed on the object side of the third lens group, the aperture stop being formed integrally with the third lens group, and the third lens group forming an aspherical surface closest to the object side; The zoom lens according to any one of claims 1 to 3, further comprising a positive lens having a positive side facing the object side. 4. The lens group according to claim 1, wherein the lens group that moves as a unit, including the fourth lens group and the fifth lens group, includes two positive lenses and one negative lens. The zoom lens according to any one of the above. The fourth lens group is composed of a cemented lens of a positive lens and a negative lens, and the refractive index and Abbe number of the positive lens are N _4p and ν _4p , respectively. _4n and ν _4n , the conditional expression:
1.45 <N _4p <1.60 (1)
60 <ν _4p <85 (2)
1.65 <N _4n <1.95 (3)
20 <ν _4n <35 (4)
The zoom lens according to claim 8, wherein the following condition is satisfied. The focal length of the entire lens system at the wide angle end and f _W, the focal length of the entire lens system at the telephoto end and f _T, the focal length of the fifth lens group as f _5, Condition:
2.5 <f ₅ / f _W <8.5 (5)
_{0.3 <f 5 / f T <} 2.0 (6)
The zoom lens according to any one of claims 1 to 3, wherein the following formula is satisfied. The fourth lens group moves toward the object side such that the distance between the third lens group and the fourth lens group decreases with zooming from the wide-angle end to the telephoto end. The zoom lens according to any one of claims 1 to 3. The amount of change in distance from the wide-angle end and the second lens group and the third lens group with zooming to the telephoto end and ZD _12, and the third lens group during zooming from the wide-angle end to the telephoto end the amount of change in distance between the fourth lens group and ZD _34, the amount of change in distance between the fifth lens group and the fourth lens group during zooming from the wide-angle end to the telephoto end and ZD _45, wide the focal length of the entire lens system at the end as f _W, condition:
2.00 <ZD ₁₂ / f _W <8.00 (7)
_{0.35 <ZD 34 / f W <} 3.45 (8)
_{1.00 <ZD 45 / f W <} 5.00 (9)
The zoom lens according to claim 11, wherein the following condition is satisfied. The focal length of the entire lens system at the telephoto end and f _T, the focal length of the first lens group and f _1, the focal length of the second lens group as f _2, Condition:
_{0.20 <| f 2 / f T} | <0.35 (10)
1.00 <| f ₁ / f _T | <3.50 (11)
The zoom lens according to claim 12, wherein the following condition is satisfied. A camera using the zoom lens according to any one of claims 1 to 12 as a photographing optical system.

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