JP3851677B2

JP3851677B2 - Zoom lens

Info

Publication number: JP3851677B2
Application number: JP04216596A
Authority: JP
Inventors: 勉鵜澤
Original assignee: Olympus Corp
Current assignee: Olympus Corp
Priority date: 1996-02-06
Filing date: 1996-02-06
Publication date: 2006-11-29
Anticipated expiration: 2016-02-06
Also published as: JPH09211326A

Description

【０００１】
【発明の属する技術分野】
本発明は、ズームレンズ特にビデオカメラに適した広画角のズームレンズに関するものである。
【０００２】
【従来の技術】
近年、民生用ビデオカメラのズームレンズにおいて高変倍のレンズ系として、物体側から順に正、負、正、正の４群構成でそのうちの負の第２群により変倍を行ない正の第４群にて変倍による像位置の変動の補正とフォーカシングとを行なうものが主流である。このタイプのズームレンズは、高変倍にするためには有利であるが鏡枠構成が複雑でありまた広画角化には不利である。
【０００３】
又、変倍比が２〜３倍程度と低いものの簡単な構成のズームレンズの従来例として特開昭６３−２９２１０６号、特開平３−２８８１１３号、特開平３−２０３７０９号の各公報に記載されたズームレンズのように、負、正、正の３群構成のものが知られている。これら従来例のような負、正、正の３群構成は、高変倍には向かないが、広角化には有利であり鏡枠構成を４群構成のものに比べて簡単になし得る等の利点を有している。
【０００４】
【発明が解決しようとする課題】
上記３群構成の従来例のうち、特開昭６３−２９２１０６号公報に記載されているズームレンズは、画角（２ω）が７０°程度と広いが、明るさ絞りおよびフレアー絞りがズーミングの際に光軸方向に移動するために、レンズ群が３群と少ないにもかかわらず鏡枠構造が複雑になる。又特開平３−２８８１１３号公報に記載されているズームレンズは、画角（２ω）が４６°と狭く、また特開平３−２０３７０９号に記載されているズームレンズも画角（２ω）が４４°と狭い。
【０００５】
本発明は、負、正、正の３群構成であって、画角（２ω）が６５°程度、変倍比が２〜３程度で簡単な鏡枠構成の、ビデオカメラに適した広画角のズームレンズを提供することにある。
【０００６】
【課題を解決するための手段】
本発明のズームレンズは、例えば図１に示すような構成のもので、物体側より順に、負の屈折力を有する第１群と正の屈折力を有する第２群と正の屈折力を有する第３群とよりなり、変倍の際、第１群が広角端に比べて望遠端において像側に位置するように移動し、第２群が固定され、第３群が広角端から望遠端にかけて像側から物体側へ単調に移動し、明るさ絞りが第１群から第３群の間の光軸上に固定配置されていることを特徴とする。
【０００７】
３群構成のズームレンズにおいて、広角化を達成するためには、広角端における第１群、第３群、明るさ絞りの配置が重要である。本発明では、明るさ絞りを第１群と第３群のほぼ中央に配置することにより第１群と第３群を通る軸外光線高を低く抑えるようにして、レンズの径を小さくすることと、軸外収差の補正とを可能にし、その結果広画角化を実現し得るようになった。このように構成した上で、変倍の際に明るさ絞りを挟んで第１群を広角端に比べて望遠端で像側に位置するように移動させ、第３群を広角端から望遠端にかけて第１群とは逆に物体側へ単調に移動させることにより明るさ絞りを第２群の近傍に固定したまま第１群と第３群の間の空間を有効に利用して変倍を行なうことが出来る。又変倍中明るさ絞りを第２群と共に固定することにより鏡枠構造を簡単にできる。又第２群は、第１群からの発散光束の発散角度を小さくして第３群への入射光線高を低く抑える作用と全系のバックフォーカスを調整する作用とを有している。このように第３群への入射光線高を低く抑えることにより第３群の小型化と収差補正に有利になる。またレンズ系と撮像素子の間に配置する光学フィルター等の光学部材の厚さに応じた適切なバックフォーカスを確保することが出来る。
【０００８】
以上のように、本発明のズームレンズは、上記の通りの構成にすることにより広画角でありながら簡易な構成になし得た。
【０００９】
又、レンズ系のコストを低減させるためには、各群を構成するレンズを必要最小限にすることが好ましい。
【００１０】
第１群は、物体側から順に、像側に凹面を向けた負レンズと、像側に凸面を向けた正レンズと、物体側に凹面を向けた負レンズとにて構成することが望ましい。
【００１１】
レンズ系の広画角化においては、特に歪曲収差と倍率の色収差の補正が重要である。まず、歪曲収差の補正に関しては、負の屈折力を二つに分割して歪曲収差の発生を小さくするのが好ましい。その上で歪曲収差の補正の不足分は、１枚の正レンズを用いることにより補正可能になる。この正レンズの配置は、第１群を対称性のよい配置にするのが倍率の色収差を補正する上で有利であり、二つの負レンズの間に配置して第１群を負、正、負の対称性の良い配置にするのが望ましい。その上最も物体側の負レンズを像側に凹面を向け、正レンズを像側に凸面を向け、像側の負レンズを物体側に凹面を向けた配置にすれば歪曲収差と倍率の色収差の補正にとってより好ましい。
【００１２】
又第２群は、正レンズ１枚のみにて構成するのが好ましい。この第２群の収差補正上の役割は、第１群および第３群で補正過剰になる球面収差と軸上色収差をバランスさせてレンズ系全体のこれら収差を良好に補正するためには１枚の正レンズにて構成することが可能である。
【００１３】
第３群は、物体側から順に、正レンズ、負レンズ、正レンズの３枚又は正レンズ、負レンズ、正レンズ、正レンズの４枚にて構成することが望ましい。この第３群は、変倍作用と結像作用とを有するために、少なくとも正レンズと負レンズと正レンズよりなるトリプレットタイプにするのが望ましく、又像側の正レンズを２枚に分割して正レンズ、負レンズ、正レンズ、正レンズの４枚構成にすれば軸外収差の補正上有利である。
【００１４】
また、レンズ系の一層の小型化と収差を更に良好に補正するためには、下記条件（１）、（２）、（３）を満足することが望ましい。
【００１５】
（１） −１．５＜ｆ₁ ／ｆ₃ ＜−０．４
（２）１．６＜ｆ₂ ／ｆ₃ ＜９
（３）０．５＜ｚ₁ ／ｚ₃ ＜４
ただし、ｆ₁ ，ｆ₂ ，ｆ₃ は夫々第１群、第２群、第３群の焦点距離、ｚ₁ ，ｚ₃ は夫々第１群および第３群の広角端と望遠端の位置の変位量の絶対値である。
【００１６】
条件（１）は、レンズの小型化に関するもので、第１群と第３群の屈折力の比を規定したものである。本発明のズームレンズにおいて、効率の良い変倍を行なうためには、第１群に十分な屈折力を持たせることが好ましい。条件（１）において下限の−１．５を越えると第１群の屈折力が弱くなりレンズ系の全長が増大し又第１群のレンズ径も増大する。又条件（１）において、上限の−０．４を越えると負の歪曲収差が増大する。
【００１７】
条件（２）は、適切なバックフォーカスを確保するために定めた条件で、第２群と第３群の屈折力の比を規定したものである。条件（２）にいおて、下限の１．６を越えるとバックフォーカスを確保する上で不利になり光学フィルターの配置が制限される。条件（２）の上限の９を越えると、バックフォーカスの確保には有利であるが、レンズ系の全長が増大し好ましくない。
【００１８】
条件（３）は、広画角化と変倍効率に関するもので、第１群と第３群の移動を規定したものである。条件（３）の上限の４を越えると広画角化には有利であるが、変倍比の確保にとって不利である。又下限の０．５を越えると変倍比の確保には有利であるが、広角化には不利である。
【００１９】
上記の本発明のズームレンズは、条件（２）において下限を１．８又は上限を７あるいは下限、上限を夫々１．８、７にすればより好ましい。つまり条件（２）の代わりに下記のいずれかの条件を満足することが望ましい。
【００２０】
（２−１）１．８＜ｆ_２／ｆ_３＜９
（２−２）１．６＜ｆ_２／ｆ_３＜７
（２−３）１．８＜ｆ_２／ｆ_３＜７
更に条件（２）の下限を２にするか上限を５にするかあるいは下限、上限をそれぞれ２、５にすれば一層望ましい。つまり下記条件を満足することが望ましい。
【００２１】
（２−４）２＜ｆ_２／ｆ_３＜９
（２−５）１．６＜ｆ_２／ｆ_３＜５
（２−６）２＜ｆ_２／ｆ_３＜５
又条件（２）の代わりに下記の条件を満足しても良い。
【００２２】
（２−７）２＜ｆ_２／ｆ_３＜７
（２−８）１．８＜ｆ_２／ｆ_３＜５
又、条件（３）において下限を０．８にするか、その上限を３．５にするかあるいは下限と上限を夫々０．８、３．５にすればより好ましい。
【００２３】
（３−１）０．８＜ｚ₁／ｚ₃＜４
（３−２）０．５＜ｚ₁／ｚ₃＜３．５
（３−３）０．８＜ｚ₁／ｚ₃＜３．５
更に、条件（３）において、下限を１．２にするか、上限を３にするか、あるいは、下限および上限を夫々１．２、３にすれば一層望ましい。
【００２４】
（３−４）１．２＜ｚ₁／ｚ₃＜４
（３−５）０．５＜ｚ₁／ｚ₃＜３
（３−６）１．２＜ｚ₁／ｚ₃＜３
又条件（３）の代わりに下記条件を満足してもよい。
【００２５】
（３−７）１．２＜ｚ₁／ｚ₃＜３．５
（３−８）０．８＜ｚ₁／ｚ₃＜３
又本発明のズームレンズにおいて、条件（２）、（３）の両方共これら条件の代わりに上記条件を満足するレンズ系としてもよい。つまり条件（２）の代わりに条件（２−１）〜条件（２−８）のいずれかをそして同時に条件（３）の代わりに条件（３−１）〜条件（３−８）を満足する構成のレンズ系でもよい。
【００２６】
本発明のズームレンズに非球面を用いれば収差補正やレンズ系の小型化にとって有利である。非球面を第１群中のレンズ面に導入する場合は、光軸から離れるにつれて負の屈折力が弱くなる形状か、あるいは正の屈折力が強くなる形状がよい。又非球面を第２群又は第３群中の面に採用する場合には、光軸から離れるにつれて正の屈折力が弱くなるか、あるいは負の屈折力が強くなる形状が望ましい。
【００２７】
次にフォーカシングに関しては、本発明のズームレンズのように、広画角で特に小さな撮像素子に用いるレンズ系の場合、被写界深度が深くフォーカシングを行なわなくとも通常の撮影が可能である。しかしより近距離まで撮影を行なう場合、フォーカシングを行なう必要がある。
【００２８】
本発明のズームレンズでは、第１群、第２群、第３群のいずれかの群を移動させるか、あるいはレンズ系全体を移動させてフォーカシングを行なうことが出来る。又は撮像素子を移動させてフォーカシングを行なってもよい。
【００２９】
第１群又は第３群あるいはレンズ系全体を移動させて近距離物体にフォーカシングを行なう場合は物体側へ移動させる。又第２群あるいは撮像素子によりフォーカシングを行なう場合は、近距離物体に対し像側へ移動させてフォーカシングを行なう。
【００３０】
上記フォーカシングにおいて、第１群でフォーカシングを行なう場合は、収差変動が少なくより近距離にフォーカシングするのに適している。又第２群でフォーカシングする場合は、本発明のズームレンズが変倍時第２群は固定でありフォーカシング時のみ移動するため、第２群の移動の制御を簡単に行ない得る。又第３群でフォーカシングを行なう場合は、この第２群はもともと可動であるためフォーカシングのために可動群を増やす必要がなく鏡枠の構成が簡単である。
【００３１】
又レンズ系全体でフォーカシングを行なう場合、又は撮像素子を移動させてフォーカシングを行なう場合は、第１群による場合と同様、収差変動が少なくより近距離にフォーカシングするのに適している。
【００３２】
尚、本発明のズームレンズにおいて、撮像素子に入射する主光線の角度を適切に保つためのレンズ群を第３群の像側に配置してもよい。
【００３３】
【発明の実施の形態】
本発明のズームレンズの実施の形態を次に示す各実施例をもとに述べる。
【００３４】
本発明のズームレンズの実施例１〜実施例７は、夫々図１〜図７に示す通りの構成で、下記のデーターを有するものである。

【００３５】

【００３６】

【００３７】

【００３８】

【００３９】

【００４０】

これら実施例は、負の第１群と正の第２群と正の第３群とよりなり、データー中に記載したように変倍のために間隔Ｄ₁ ，Ｄ₂ ，Ｄ₃ が変化する。
【００４１】
又、各実施例の第１群、第２群、第３群の構成および絞りの配置位置は次の通りである。
【００４２】
実施例１〜実施例５は、いずれも第１群が物体側から順に、像側に凹面を向けた負レンズと像側に凸面を向けた正レンズと物体側に凹面を向けた負レンズとからなり、第２群が正レンズ１枚からなり、第３群が物体側から順に、正レンズと負レンズと正レンズと正レンズの４枚のレンズからなり、絞りが第２群の像側に固定配置されている。
【００４３】
実施例６は、絞りが第２群の物体側に固定配置されている点を除いて前記実施例１〜５と同じ構成である。
【００４４】
実施例７は、第３群が物体側より順に、正レンズと負レンズと正レンズの３枚のレンズよりなる点で他の実施例と相違する。又絞りは実施例６と同様に第２群の物体側に固定配置されている。
【００４５】
上記実施例において、実施例４の面ｒ₇ 、実施例５の面ｒ₁₀、実施例６の面ｒ₄ とｒ₁₀、実施例７の面ｒ₁₀は、いずれも光軸方向をｘ軸、光軸に垂直な方向をｙ軸とした時に下記の式にて表わされる非球面である。

【００４６】
ただし、ｒは非球面の面頂における曲率半径、Ｋは円錐定数、Ａ₄ ，Ａ₆ ，Ａ₈ ，・・・は夫々４次、６次、８次、・・・の非球面係数である。
【００４７】
又、各実施例のズーミング・フォーカシング時の間隔の変化はデーター中に示す通りで、Ｗ（∞）、Ｓ（∞）、Ｔ（∞）は夫々無限遠フォーカス時の広角端、中間焦点距離、望遠端の可変間隔、Ｗ (200)、Ｓ (200)、Ｔ (200)は夫々物体距離２００mmの物体にフォーカシングした時の広角端、中間焦点距離、望遠端の可変間隔、Ｗ (400)、Ｓ (400)、Ｔ (400)は夫々４００mmの物体にフォーカシングした時の広角端、中間焦点距離、望遠端の可変間隔を示す。
【００４８】
尚データー中、実施例１，２，３は、夫々第１群、第２群、第３群、レンズ系全体を移動させてフォーカシングを行なった時の間隔を示してある。実施例１における第２群によるフォーカシング時、絞りは固定であるため第２群と絞りとの間の間隔ｄ₈ が変化する。又、実施例２，３は、いずれも第２群によりフォーカシングを行なうために第２群を絞りの側へ移動させた時に第２群が絞りに当たるため第２群と絞りとを一体に移動させてフォーカシングを行なっている。したがってこの第２群によるフォーカシング時、第２群の最も像側の面と絞りとの間の間隔ｄ₈ は不変であり、絞りと第３群の物体側の面間隔ｄ₉ （Ｄ₂ ）が変化する。
【００４９】
実施例４〜７のデーターも実施例１，２，３と同様に第１群、第２群、第３群、レンズ系全体によるフォーカシングのうちのいずれも可能である。
【００５０】
尚各実施例の収差図は、上段はワイド端、中断が中間の焦点距離、下段はテレ端におけるものである。
【００５１】
本発明のズームレンズは、特許請求の範囲に記載のもののほか、次の各項に記載するものも目的を達成し得る。
【００５２】
（１）特許請求の範囲の請求項１、２又は３に記載されているレンズ系で、前記第３群が物体側から順に、正レンズ、負レンズ、正レンズの３枚又は、正レンズ、負レンズ、正レンズ、正レンズの４枚のレンズよりなるズームレンズ。
【００５３】
（２）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件（１）、（２）、（３）を満足するズームレンズ。
【００５４】
（１） −１．５＜ｆ₁ ／ｆ₃ ＜−０．４
（２）１．６＜ｆ₂ ／ｆ₃ ＜９
（３）０．５＜Ｚ₁ ／Ｚ₃ ＜４
（３）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００５５】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−１）１．８＜ｆ_２／ｆ_３＜９
（３）０．５＜Ｚ_１／Ｚ_３＜４
（４）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００５６】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−２）１．６＜ｆ_２／ｆ_３＜７
（３）０．５＜Ｚ_１／Ｚ_３＜４
（５）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００５７】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−３）１．８＜ｆ_２／ｆ_３＜７
（３）０．５＜Ｚ_１／Ｚ_３＜４
（６）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００５８】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−４）２＜ｆ_２／ｆ_３＜９
（３）０．５＜Ｚ_１／Ｚ_３＜４
（７）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００５９】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−５）１．６＜ｆ_２／ｆ_３＜５
（３）０．５＜Ｚ_１／Ｚ_３＜４
（８）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６０】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−６）２＜ｆ_２／ｆ_３＜５
（３）０．５＜Ｚ_１／Ｚ_３＜４
（９）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６１】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−７）２＜ｆ_２／ｆ_３＜７
（３）０．５＜Ｚ_１／Ｚ_３＜４
（１０）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６２】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２−８）１．８＜ｆ_２／ｆ_３＜５
（３）０．５＜Ｚ_１／Ｚ_３＜４
（１１）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６３】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−１）０．８＜Ｚ_１／Ｚ_３＜４
（１２）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６４】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−２）０．５＜Ｚ_１／Ｚ_３＜３．５
（１３）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６５】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−３）０．８＜Ｚ_１／Ｚ_３＜３．５
（１４）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６６】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−４）１．２＜Ｚ_１／Ｚ_３＜４
（１５）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６７】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−５）０．５＜Ｚ_１／Ｚ_３＜３
（１６）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６８】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−６）１．２＜Ｚ_１／Ｚ_３＜３
（１７）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００６９】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−７）１．２＜Ｚ_１／Ｚ_３＜３．５
（１８）特許請求の範囲の請求項１、２又は３あるいは前記の（１）の項に記載されているレンズ系で、下記条件を満足するズームレンズ。
【００７０】
（１） −１．５＜ｆ_１／ｆ_３＜−０．４
（２）１．６＜ｆ_２／ｆ_３＜９
（３−８）０．８＜Ｚ_１／Ｚ_３＜３
【００７１】
【発明の効果】
本発明によれば、負、正、正の３群構成であって、画角が６５°程で、高倍比が２〜３程で、簡易な鏡枠構成になし得るビデオカメラに適した広画角のズームレンズを実現し得るものである。
【図面の簡単な説明】
【図１】本発明の実施例１の構成を示す図
【図２】本発明の実施例２の構成を示す図
【図３】本発明の実施例３の構成を示す図
【図４】本発明の実施例４の構成を示す図
【図５】本発明の実施例５の構成を示す図
【図６】本発明の実施例６の構成を示す図
【図７】本発明の実施例７の構成を示す図
【図８】実施例１の無限遠の物体にフォーカスした時の収差曲線図
【図９】実施例１の第１群により２００mmの物体にフォーカスした時の収差曲線図
【図１０】実施例１の第２群により２００mmの物体にフォーカスした時の収差曲線図
【図１１】実施例１の第３群により２００mmの物体にフォーカスした時の収差曲線図
【図１２】実施例１のレンズ系全体により２００mmの物体にフォーカスした時の収差曲線図
【図１３】実施例２の無限遠の物体にフォーカスした時の収差曲線図
【図１４】実施例２の第１群により２００mmの物体にフォーカスした時の収差曲線図
【図１５】実施例２の第２群により２００mmの物体にフォーカスした時の収差曲線図
【図１６】実施例２の第３群により４００mmの物体にフォーカスした時の収差曲線図
【図１７】実施例２のレンズ系全体により２００mmの物体にフォーカスした時の収差曲線図
【図１８】実施例３の無限遠の物体にフォーカスした時の収差曲線図
【図１９】実施例３の第１群により２００mmの物体にフォーカスした時の収差曲線図
【図２０】実施例３の第２群により２００mmの物体にフォーカスした時の収差曲線図
【図２１】実施例３の第３群により４００mmの物体にフォーカスした時の収差曲線図
【図２２】実施例３のレンズ系全体により２００mmの物体にフォーカスした時の収差曲線図
【図２３】実施例４の無限遠物体にフォーカスした時の収差曲線図
【図２４】実施例５の無限遠物体にフォーカスした時の収差曲線図
【図２５】実施例６の無限遠の物体にフォーカスした時の収差曲線図
【図２６】実施例７の無限遠物体にフォーカスした時の収差曲線図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zoom lens, particularly a zoom lens having a wide angle of view suitable for a video camera.
[0002]
[Prior art]
In recent years, a zoom lens of a consumer video camera has a positive zoom ratio as a high zoom ratio lens system in which positive, negative, positive, and positive four groups are arranged in order from the object side, and the negative second group is used for zooming. It is the mainstream to perform correction and focusing of image position variation due to zooming in a group. This type of zoom lens is advantageous for achieving a high zoom ratio but has a complicated lens frame configuration and is disadvantageous for widening the angle of view.
[0003]
In addition, as conventional examples of zoom lenses having a simple configuration although the zoom ratio is as low as about 2 to 3 times, they are described in Japanese Patent Laid-Open Nos. 63-292106, 3-288113, and 3-203709. A zoom lens having a three-group configuration of negative, positive, and positive is known. The negative, positive, and positive three-group configuration as in the conventional example is not suitable for high zooming, but is advantageous for widening the angle, and the lens frame configuration can be easily made compared to the four-group configuration. Has the advantage of
[0004]
[Problems to be solved by the invention]
Among the conventional examples of the above three-group configuration, the zoom lens described in Japanese Patent Application Laid-Open No. 63-292106 has a wide angle of view (2ω) of about 70 °, but the aperture stop and flare stop are zoomed. Therefore, the lens frame structure is complicated even though the number of lens groups is as small as three. The zoom lens described in JP-A-3-288113 has a narrow angle of view (2ω) of 46 °, and the zoom lens described in JP-A-3-203709 also has an angle of view (2ω) of 44. ° and narrow.
[0005]
The present invention has a three-group configuration of negative, positive, and positive, a wide angle suitable for a video camera having a simple lens frame configuration with an angle of view (2ω) of about 65 ° and a zoom ratio of about 2-3. It is to provide a corner zoom lens.
[0006]
[Means for Solving the Problems]
The zoom lens of the present invention has, for example, a configuration as shown in FIG. 1 and has, in order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a positive refractive power. When the zooming operation is performed, the first group moves so as to be positioned closer to the image side at the telephoto end than at the wide angle end, the second group is fixed, and the third group is moved from the wide angle end to the telephoto end. , And the brightness stop is fixedly arranged on the optical axis between the first group and the third group.
[0007]
In a zoom lens having a three-group structure, in order to achieve a wide angle, the arrangement of the first group, the third group, and the aperture stop at the wide-angle end is important. In the present invention, the diameter of the lens is reduced by disposing the aperture stop substantially at the center of the first group and the third group so as to keep the off-axis ray height passing through the first group and the third group low. And off-axis aberration correction, and as a result, a wide angle of view can be realized. With this configuration, when zooming, the first lens unit is moved so as to be positioned closer to the image side at the telephoto end than the wide angle end with the aperture stop interposed therebetween, and the third lens unit is moved from the wide angle end to the telephoto end. In contrast to the first group, by moving monotonically toward the object side, the aperture stop is fixed in the vicinity of the second group, and the magnification between the first group and the third group is effectively utilized. Can be done. The lens frame structure can be simplified by fixing the aperture stop together with the second group during zooming. The second group has an action of reducing the divergent angle of the divergent light beam from the first group to reduce the incident light height to the third group and adjusting the back focus of the entire system. Thus, by suppressing the height of the incident light beam to the third group, it becomes advantageous for downsizing and aberration correction of the third group. In addition, it is possible to ensure an appropriate back focus according to the thickness of an optical member such as an optical filter disposed between the lens system and the image sensor.
[0008]
As described above, the zoom lens according to the present invention can have a simple configuration while having a wide angle of view by adopting the configuration as described above.
[0009]
Further, in order to reduce the cost of the lens system, it is preferable to minimize the lenses constituting each group.
[0010]
It is desirable that the first group is composed of, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the image side, and a negative lens having a concave surface facing the object side.
[0011]
In widening the angle of view of the lens system, it is particularly important to correct distortion and lateral chromatic aberration. First, regarding the correction of distortion, it is preferable to divide the negative refractive power into two to reduce the occurrence of distortion. In addition, the shortage of correction of distortion can be corrected by using one positive lens. In the arrangement of the positive lens, it is advantageous in correcting the chromatic aberration of magnification that the first group is arranged with good symmetry, and the first group is arranged between two negative lenses so that the first group is negative, positive, It is desirable to have an arrangement with good negative symmetry. In addition, if the negative lens on the most object side has a concave surface facing the image side, the positive lens faces the convex surface to the image side, and the negative lens on the image side faces the concave surface on the object side, then distortion and magnification chromatic aberration More preferable for correction.
[0012]
The second group is preferably composed of only one positive lens. The second group has a role in correcting aberrations in order to balance the spherical aberration and axial chromatic aberration that are overcorrected in the first group and the third group and to correct these aberrations in the entire lens system. The positive lens can be used.
[0013]
The third group is preferably composed of three lenses, a positive lens, a negative lens, and a positive lens, or four lenses of a positive lens, a negative lens, a positive lens, and a positive lens in order from the object side. Since this third group has a zooming action and an imaging action, it is desirable to use a triplet type comprising at least a positive lens, a negative lens and a positive lens, and the image side positive lens is divided into two. Therefore, it is advantageous in correcting off-axis aberrations if a four-lens configuration of positive lens, negative lens, positive lens, and positive lens is used.
[0014]
In order to further reduce the size of the lens system and correct aberrations, it is desirable to satisfy the following conditions (1), (2), and (3).
[0015]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3) 0.5 <z ₁ / z ₃ <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.
[0016]
Condition (1) relates to the downsizing of the lens and defines the ratio of the refractive powers of the first group and the third group. In the zoom lens according to the present invention, it is preferable that the first lens unit has a sufficient refractive power in order to perform efficient zooming. If the lower limit of -1.5 in condition (1) is exceeded, the refractive power of the first group becomes weak, the total length of the lens system increases, and the lens diameter of the first group also increases. Also, if the upper limit of −0.4 is exceeded in condition (1), negative distortion increases.
[0017]
Condition (2) is a condition determined to ensure an appropriate back focus, and defines the ratio of the refractive powers of the second group and the third group. In the condition (2), if the lower limit of 1.6 is exceeded, it is disadvantageous for securing the back focus, and the arrangement of the optical filter is limited. Exceeding the upper limit of 9 to condition (2) is advantageous for securing the back focus, but is not preferable because the total length of the lens system increases.
[0018]
Condition (3) relates to widening the angle of view and zooming efficiency, and defines the movement of the first group and the third group. Exceeding the upper limit of 4 to condition (3) is advantageous for widening the angle of view, but is disadvantageous for securing a zoom ratio. If the lower limit of 0.5 is exceeded, it is advantageous for securing a zoom ratio, but it is disadvantageous for widening the angle.
[0019]
In the zoom lens of the present invention, it is more preferable that the lower limit is 1.8 or the upper limit is 7, or the lower limit and the upper limit are 1.8 and 7, respectively, in the condition (2). That is, it is desirable to satisfy any of the following conditions instead of the condition (2).
[0020]
(2-1) 1.8 <f ₂ / f ₃ <9
(2-2) 1.6 <f ₂ / f ₃ <7
(2-3) 1.8 <f ₂ / f ₃ <7
Furthermore, it is more desirable to set the lower limit of the condition (2) to 2, set the upper limit to 5, or set the lower limit and the upper limit to 2, 5 respectively. That is, it is desirable to satisfy the following conditions.
[0021]
(2-4) 2 <f ₂ / f ₃ <9
(2-5) 1.6 <f ₂ / f ₃ <5
(2-6) 2 <f ₂ / f ₃ <5
Further, the following condition may be satisfied instead of condition (2).
[0022]
(2-7) 2 <f ₂ / f ₃ <7
(2-8) 1.8 <f ₂ / f ₃ <5
In the condition (3), it is more preferable to set the lower limit to 0.8, set the upper limit to 3.5, or set the lower limit and the upper limit to 0.8 and 3.5 , respectively.
[0023]
(3-1) 0.8 <z ₁ / z ₃ <4
(3-2) 0.5 <z ₁ / z ₃ <3.5
(3-3) 0.8 <z ₁ / z ₃ <3.5
Furthermore, in condition (3), it is more desirable to set the lower limit to 1.2, set the upper limit to 3, or set the lower limit and the upper limit to 1.2 and 3, respectively.
[0024]
(3-4) 1.2 <z ₁ / z ₃ <4
(3-5) 0.5 <z ₁ / z ₃ <3
(3-6) 1.2 <z ₁ / z ₃ <3
Further, the following condition may be satisfied instead of condition (3).
[0025]
(3-7) 1.2 <z ₁ / z ₃ <3.5
(3-8) 0.8 <z ₁ / z ₃ <3
In the zoom lens of the present invention, both the conditions (2) and (3) may be a lens system that satisfies the above conditions instead of these conditions. That is, any one of the conditions (2-1) to (2-8) is satisfied instead of the condition (2), and the conditions (3-1) to (3-8) are satisfied instead of the condition (3). A lens system having a configuration may be used.
[0026]
Use of an aspherical surface for the zoom lens of the present invention is advantageous for aberration correction and lens system size reduction. In the case of introducing an aspherical surface to the lens surface in the first group, a shape in which the negative refractive power decreases as the distance from the optical axis decreases, or a shape in which the positive refractive power increases is preferable. When an aspherical surface is adopted as the surface in the second group or the third group, it is desirable that the positive refractive power becomes weaker or the negative refractive power becomes stronger as the distance from the optical axis increases.
[0027]
Next, with respect to focusing, in the case of a lens system used for an image pickup device having a wide angle of view and a particularly small angle like the zoom lens of the present invention, normal shooting can be performed without deep focusing and without performing focusing. However, it is necessary to perform focusing when shooting to a closer distance.
[0028]
In the zoom lens of the present invention, focusing can be performed by moving any of the first group, the second group, and the third group, or by moving the entire lens system. Alternatively, focusing may be performed by moving the image sensor.
[0029]
When focusing on a short-distance object by moving the first group, the third group, or the entire lens system, the lens group is moved to the object side. When focusing is performed by the second group or the image sensor, focusing is performed by moving the object to the image side with respect to a short-distance object.
[0030]
In the focusing described above, when focusing is performed in the first group, there is little variation in aberrations, and it is suitable for focusing at a shorter distance. In the case of focusing in the second group, since the zoom lens of the present invention is fixed when the zoom lens is zoomed and moves only during focusing, the movement of the second group can be easily controlled. When focusing is performed in the third group, since the second group is originally movable, it is not necessary to increase the number of movable groups for focusing, and the configuration of the lens frame is simple.
[0031]
Also, when focusing is performed on the entire lens system, or when focusing is performed by moving the image pickup element, as in the case of the first group, it is suitable for focusing at a short distance with less aberration fluctuation.
[0032]
In the zoom lens of the present invention, a lens group for appropriately maintaining the angle of the principal ray incident on the image sensor may be disposed on the image side of the third group.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the zoom lens of the present invention will be described based on the following examples.
[0034]
Embodiments 1 to 7 of the zoom lens according to the present invention have the following data with the configurations shown in FIGS.

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

These examples consist of a negative first group, a positive second group, and a positive third group, and the intervals D ₁ , D ₂ , and D ₃ change due to scaling as described in the data. .
[0041]
The configurations of the first group, the second group, and the third group and the arrangement positions of the diaphragms in each example are as follows.
[0042]
In each of Examples 1 to 5, in order from the object side, the first lens unit has a negative lens having a concave surface directed to the image side, a positive lens having a convex surface directed to the image side, and a negative lens having a concave surface directed to the object side. The second group is composed of one positive lens, the third group is composed of four lenses of a positive lens, a negative lens, a positive lens, and a positive lens in order from the object side, and the aperture is on the image side of the second group. It is fixedly arranged.
[0043]
The sixth embodiment has the same configuration as the first to fifth embodiments except that the diaphragm is fixedly disposed on the object side of the second group.
[0044]
The seventh embodiment is different from the other embodiments in that the third group is composed of three lenses of a positive lens, a negative lens, and a positive lens in order from the object side. As in the sixth embodiment, the diaphragm is fixedly disposed on the object side of the second group.
[0045]
In the above embodiments, the surface r ₇ of Example 4, the surface r ₁₀ of Example 5, the surface r ₄ and r ₁₀ of Example 6, the surface r ₁₀ of Example 7, x-axis both in the optical axis direction, An aspherical surface represented by the following formula when the direction perpendicular to the optical axis is the y-axis.

[0046]
Where r is the radius of curvature at the top of the aspheric surface, K is the conic constant, A ₄ , A ₆ , A ₈ ,... Are the aspheric coefficients of the _fourth , _sixth , _eighth ,. .
[0047]
In addition, the change in the interval during zooming focusing in each embodiment is as shown in the data, and W (∞), S (∞), and T (∞) are the wide-angle end, the intermediate focal length at the time of infinity focus, Variable distance at the telephoto end, W (200), S (200), T (200) are the wide angle end, intermediate focal length, variable distance at the telephoto end when focusing on an object with an object distance of 200 mm, W (400), S (400) and T (400) indicate variable intervals of the wide-angle end, the intermediate focal length, and the telephoto end, respectively, when focusing on a 400 mm object.
[0048]
In the data, Examples 1, 2, and 3 show the intervals when focusing is performed by moving the first group, the second group, the third group, and the entire lens system, respectively. At the time of focusing by the second group in the first embodiment, since the diaphragm is fixed, the distance d ₈ between the second group and the diaphragm changes. In each of the second and third embodiments, the second group hits the diaphragm when the second group is moved to the diaphragm side in order to perform focusing by the second group, so that the second group and the diaphragm are moved together. Focusing. Therefore, at the time of focusing by the second group, the distance d ₈ between the most image side surface of the second group and the stop is unchanged, and the surface distance d ₉ (D ₂ ) between the stop and the object side of the third group is constant. Change.
[0049]
Similarly to the first, second, and third embodiments, the data of the fourth to seventh embodiments can be any of the first group, the second group, the third group, and focusing by the entire lens system.
[0050]
In the aberration diagrams of the examples, the upper stage is at the wide end, the interruption is at the intermediate focal length, and the lower stage is at the tele end.
[0051]
The zoom lens of the present invention can achieve the object in addition to those described in the claims, and those described in the following items.
[0052]
(1) In the lens system described in claim 1, 2 or 3, the third group is, in order from the object side, three positive lenses, a negative lens, and a positive lens, or a positive lens, A zoom lens consisting of four lenses: a negative lens, a positive lens, and a positive lens.
[0053]
(2) A zoom lens satisfying the following conditions (1), (2), and (3) in the lens system described in claim 1, 2 or 3 of the claims or the item (1) above .
[0054]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
_{(3) 0.5 <Z 1 /} Z 3 <4
(3) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0055]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-1) 1.8 <f ₂ / f ₃ <9
(3) 0.5 <Z ₁ / Z ₃ <4
(4) A zoom lens satisfying the following conditions in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0056]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-2) 1.6 <f ₂ / f ₃ <7
(3) 0.5 <Z ₁ / Z ₃ <4
(5) A zoom lens system that satisfies the following conditions in the lens system described in claim 1, 2, 3 or claim 1 or (1).
[0057]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-3) 1.8 <f ₂ / f ₃ <7
(3) 0.5 <Z ₁ / Z ₃ <4
(6) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0058]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-4) 2 <f ₂ / f ₃ <9
(3) 0.5 <Z ₁ / Z ₃ <4
(7) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0059]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-5) 1.6 <f ₂ / f ₃ <5
(3) 0.5 <Z ₁ / Z ₃ <4
(8) A zoom lens satisfying the following conditions in the lens system described in claim 1, 2, 3 or claim 1 (1).
[0060]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-6) 2 <f ₂ / f ₃ <5
(3) 0.5 <Z ₁ / Z ₃ <4
(9) A zoom lens system that satisfies the following conditions in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0061]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-7) 2 <f ₂ / f ₃ <7
(3) 0.5 <Z ₁ / Z ₃ <4
(10) A zoom lens system that satisfies the following conditions in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0062]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-8) 1.8 <f ₂ / f ₃ <5
(3) 0.5 <Z ₁ / Z ₃ <4
(11) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0063]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-1) 0.8 <Z ₁ / Z ₃ <4
(12) A zoom lens satisfying the following conditions in the lens system described in claim 1, 2, 3 or claim 1 (1).
[0064]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
_{_{(3-2) 0.5 <Z 1 /}} Z 3 <3.5
(13) A zoom lens satisfying the following conditions in the lens system described in claim 1, 2, 3 or claim (1).
[0065]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
_{_{(3-3) 0.8 <Z 1 /}} Z 3 <3.5
(14) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0066]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-4) 1.2 <Z ₁ / Z ₃ <4
(15) A zoom lens satisfying the following condition in the lens system described in claim 1, 2, 3 or claim 1 or (1).
[0067]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-5) 0.5 <Z ₁ / Z ₃ <3
(16) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2, 3 or claim 1 or (1).
[0068]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-6) 1.2 <Z ₁ / Z ₃ <3
(17) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0069]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-7) 1.2 <Z ₁ / Z ₃ <3.5
(18) A zoom lens system that satisfies the following condition in the lens system described in claim 1, 2 or 3 of the claims or the item (1).
[0070]
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-8) 0.8 <Z ₁ / Z ₃ <3
[0071]
【The invention's effect】
According to the present invention, a wide three-group configuration of negative, positive, and positive, an angle of view of about 65 °, a high magnification ratio of about 2 to 3, and a wide range suitable for a video camera capable of forming a simple lens frame configuration. A zoom lens having an angle of view can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention. FIG. 2 is a diagram showing a configuration of a second embodiment of the present invention. FIG. 3 is a diagram showing a configuration of a third embodiment of the present invention. FIG. 5 is a diagram showing the configuration of the fifth embodiment of the present invention. FIG. 5 is a diagram showing the configuration of the fifth embodiment of the present invention. FIG. 6 is a diagram showing the configuration of the sixth embodiment of the present invention. FIG. 8 is an aberration curve diagram when focusing on an object at infinity according to Example 1. FIG. 9 is an aberration curve diagram when focusing on an object of 200 mm according to the first group of Example 1. 10 is an aberration curve diagram when focusing on an object of 200 mm by the second group of Example 1. FIG. 11 is an aberration curve diagram when focusing on an object of 200 mm by the third group of Example 1. FIG. FIG. 13 is an aberration curve diagram when an object of 200 mm is focused by the entire lens system of FIG. FIG. 14 is an aberration curve diagram when focusing on a 200 mm object by the first group of Example 2. FIG. 15 is a graph showing an aberration curve when focusing on a 200 mm object by the second group of Example 2. Aberration curve diagram [FIG. 16] Aberration curve diagram when focusing on a 400 mm object by the third group of Example 2. [FIG. 17] Aberration curve diagram when focusing on a 200 mm object by the entire lens system of Example 2. 18 is an aberration curve diagram when focusing on an object at infinity in Example 3. FIG. 19 is an aberration curve diagram when focusing on an object of 200 mm according to the first group of Example 3. FIG. FIG. 21 is an aberration curve diagram when focusing on an object of 200 mm by the second group. FIG. 21 is an aberration curve diagram when focusing on an object of 400 mm by the third group of Example 3. FIG. 200m FIG. 23 is an aberration curve diagram when focusing on an object at infinity in Example 4. FIG. 24 is an aberration curve diagram when focusing on an object at infinity in Example 5. FIG. 25 is an aberration curve diagram when focusing on an object at infinity according to Example 6. FIG. 26 is an aberration curve diagram when focusing on an object at infinity according to Example 7.

Claims

In order from the object side, a first group having a negative refractive power, a second group having a positive refractive power, and a third group having a positive refractive power, and the first group has a wide angle during zooming. The second lens unit is fixed, the third lens unit moves from the wide-angle end to the telephoto end, moves from the image side to the object side, and the aperture stop is the first lens unit. Zoom lens satisfying the following conditions (1), (2), and (3) in a lens system fixedly disposed on the optical axis between the first lens unit and the third lens unit.
(1) -1.5 <f ₁ / F ₃ <-0.4
(2) 1.6 <f ₂ / F ₃ <9
(3) 0.5 <Z ₁ / Z ₃ <4
Where f ₁ , F ₂ , F ₃ Are the focal lengths of the first, second and third groups, respectively, z ₁ , Z ₃ Is the absolute value of the displacement amount at the wide-angle end and the telephoto end of the first group and the third group, respectively.

2. The zoom lens according to claim 1, wherein the first group includes, in order from the object side, a negative lens having a concave surface facing the image side, a positive lens having a convex surface facing the image side, and a negative lens having a concave surface facing the object side.

The zoom lens according to claim 1, wherein the second group includes only one positive lens.

The said 3rd group consists of three lenses of a positive lens, a negative lens, and a positive lens or four lenses of a positive lens, a negative lens, a positive lens, and a positive lens in order from an object side. Zoom lens.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-1) 1.8 <f ₂ / f ₃ <9
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-2) 1.6 <f ₂ / f ₃ <7
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-3) 1.8 <f ₂ / f ₃ <7
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-4) 2 <f ₂ / f ₃ <9
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-5) 1.6 <f ₂ / f ₃ <5
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-6) 2 <f ₂ / f ₃ <5
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-7) 2 <f ₂ / f ₃ <7
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2-8) 1.8 <f ₂ / f ₃ <5
_{(3) 0.5 <Z 1 /} Z 3 <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-1) 0.8 <Z ₁ / Z ₃ <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-2) 0.5 <Z ₁ / Z ₃ <3.5
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-3) 0.8 <Z ₁ / Z ₃ <3.5
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-4) 1.2 <Z ₁ / Z ₃ <4
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-5) 0.5 <Z ₁ / Z ₃ <3
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-6) 1.2 <Z ₁ / Z ₃ <3
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-7) 1.2 <Z ₁ / Z ₃ <3.5
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.

The zoom lens according to claim 1, wherein the zoom lens satisfies the following condition.
(1) −1.5 <f ₁ / f ₃ <−0.4
(2) 1.6 <f ₂ / f ₃ <9
(3-8) 0.8 <Z ₁ / Z ₃ <3
Here, f ₁ , f ₂ , and f ₃ are the focal lengths of the first group, the second group, and the third group, respectively, and z ₁ and z ₃ are the positions of the wide-angle end and the telephoto end of the first group and the third group, respectively. This is the absolute value of the displacement.