JP4642958B2

JP4642958B2 - Compact high-magnification wide-angle zoom lens

Info

Publication number: JP4642958B2
Application number: JP2000013803A
Authority: JP
Inventors: 一輝河村; 隆則柴田
Original assignee: Olympus Corp
Current assignee: Olympus Corp
Priority date: 2000-01-24
Filing date: 2000-01-24
Publication date: 2011-03-02
Anticipated expiration: 2020-01-24
Also published as: JP2001208970A

Description

【０００１】
【発明の属する技術分野】
本発明は、小型高変倍広角レンズに関するものである。
【０００２】
【従来の技術】
高変倍であって、小型化を達成し得るズームレンズとして、物体側から順に正、負、正、正の群を有し、各群を移動させることにより変倍を行なうレンズ系が有効であることが従来より知られている。
【０００３】
このように物体側から順に、正、負、正、正の群よりなるズームレンズの従来例として特開昭５８−２０２４１８号公報の第１，第２実施例のレンズ系、米国特許明細書第４２５６３８１号の第１，第２，第３実施例のレンズ系、特開平１０−１３３１１１号公報の第１，第２実施例のレンズ系が知られている。これらのズームレンズは、広角端の画角２ωが６５°を超えるレンズ系であるが変倍比が４倍に達せず高変倍比のズームレンズとはいえない。
【０００４】
また、正、負、正、正の群よりなるズームレンズの他の従来例として、特開昭６０−２６３１２号公報に記載されている第１，第２実施例のレンズ系、特開昭４７−４５６４１号公報に記載されている第１，第２実施例のレンズ系、特開昭５６−１５０７１７号公報の第１，第２実施例のレンズ系が知られている。しかしこれらレンズ系は、広角端の画角２ωが４５°以下であって画角が狭い。
【０００５】
更に正、負、正、正の群よりなるズームレンズの他の従来例として、米国特許明細書第４２５６３８１号の第４〜第８実施例のレンズ系、米国特許明細書第４２９９４５４号の第４実施例、特開昭６３−７０８１９号公報の第１〜第４実施例のレンズ系がある。これらレンズ系は変倍比が４を超えるが、テレ端での望遠比が１．４で、レンズ系の全長が長く小型ではない。
【０００６】
【発明が解決しようとする課題】
本発明は、正、負、正、正の群の４群構成で、変倍比が４を超える高変倍で、レンズ径が小で、テレ端での望遠比が１．３以下で全長が短く、しかも画角２ωが６５°を超えるワイド端からテレ端までの全域で良好な光学性のズームレンズを提供するものである。
【０００７】
【課題を解決するための手段】
本発明のズームレンズは、物体側より順に、正の屈折力を有する第１群と、負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、正の屈折力を有する第４群とよりなり、ワイド端からテレ端への変倍に際して、第１群が物体側へ移動し、第２群が第１群との間隔を増大するように移動し、第３群が第２群との間隔を狭くするように移動し、第４群が第３群との間隔がワイド端よりもテレ端の方が狭くなるように移動し、前記第２群が物体側から順に、物体側に凸面を向けた負のメニスカスレンズを有する第１レンズ成分と負レンズを含み正の屈折力を有する第２レンズ成分と負の屈折力を有する第３レンズ成分とよりなり、前記第３群が物体側の面が像側の面よりも強い屈折力を有する正レンズとその像側に最も像側が負レンズである全体として正または負の屈折力を有するレンズ成分とよりなり、前記第４群が正レンズとその像側の負レンズとを有し、前記正レンズと前記負レンズの向かい合う各面が共に物体側に凹面を向けた隣接面を有するものである。
【０００８】
ここでレンズ成分とは、１枚又は複数枚のレンズよりなり全体として一つのレンズとしての作用，役割を備えたものであり、複数のレンズよりなる場合接合されていてもまた僅かな空気間隔をおいて分離配置されていてもよい。
【０００９】
広角からのズームレンズは、高変倍化するにしたがって、ワイド端やテレ端はもとより、中間の焦点距離域においても、像面や倍率の色収差の変動が大きく光学性能を良好に保つことが困難になる。したがって高変倍比のためには各群の移動とパワーとを適切に選ぶことが重要である。
【００１０】
そのため、本発明は前記のように物体側より順に、正、負、正、正の群よりなり、ワイド端からテレ端への変倍に際し、第１群が物体側へ移動し、第２群が第１群との間隔が増大するように移動し、第３群が第２群との間隔が狭くなるように移動し、第４群が第３群との間隔をワイド端よりテレ端が狭くなるようにした。
【００１１】
これにより、ワイド側で主として発生する軸外収差を開口絞りの物体側に配置された第１群の正のパワーと第２群の負のパワーとで良好に補正し得るようなパワー配分とし、また、テレ側では第１群を正のパワーとしてテレ端での全長が短くなるようにし、更に第２群の負のパワーと第３群と第４群の正のパワーを近接させることによって主として球面収差、コマ収差を良好に補正できるようなパワー配分を採用した。また、ワイド端からテレ端への変倍に際し、第３群と第４群を物体側へ移動させるようにすれば前記の球面収差、コマ収差の補正作用は一層効果的になる。
【００１２】
また、前述の構成の４群ズームレンズは、第２群と第３群の間隔を変化させての変倍作用を大きくすることにより高変倍化できるが、そのためには第２群の負のパワーを強める必要がある。このように第２群のパワーを強めると主としてワイド端での歪曲収差が悪化すると共に変倍時の像面変動や倍率の色収差の変動を招く。
【００１３】
本発明は、第２群を物体側より順に物体側に凸面を向けた負のメニスカスレンズを有する第１レンズ成分と、正の第２レンズ成分と正の第３レンズ成分とを夫々空気間隔を挟んで配置した構成にすることによりワイド端での歪曲収差を良好に保ったまままた変倍時の像面変動や倍率の色収差の変動を少なく保ったまま第２群のパワーを強くすることを可能にした。
【００１４】
つまり、第２群の第１レンズ成分中に物体側に凸のパワーの強い負のメニスカスレンズを含むようにして第１群にて発生する正の歪曲収差を効果的に補正することができる。しかしそのパワーを強くしすぎると主として非点収差、コマ収差、倍率の色収差の変倍時の変動が大になる。そのため、正の第２レンズ成分中に負レンズを含むようにして第１レンズ成分中の負のメニスカスレンズのパワーを分担することにより前記非点収差、コマ収差、倍率の色収差の変倍時の変動を小さくすると共に第２レンズ成分中の正レンズにより主としてワイド端付近での倍率の色収差とテレ端付近での軸上色収差を良好に補正し得るようにした。
【００１５】
また、負の第３レンズ成分により残存する色収差と球面収差、コマ収差とのバランスをコントロールし得るようにした。そして、以上の三つのレンズ成分を夫々空気間隔を挟んで独立して配置することによりレンズ系の収差を良好に確保し得るようにした。
【００１６】
また、第２レンズ成分を負レンズと正レンズの２枚のレンズにて、第３レンズ成分を１枚のレンズにて構成することも可能であり、これによりレンズ系のレンズ枚数を少なくすることができ低コスト化と軽量化が可能になる。また第２レンズ成分を負レンズと正レンズを接合させて接合レンズにすることにより枠に組み込んだ時の偏芯による性能劣化を小さくでき安定した性能を確保できる。
【００１７】
また、第２群の第１レンズ成分を負のメニスカスレンズ１枚にて構成しても収差の悪化を抑えることができ１枚のレンズのみにて構成することが可能であり、レンズ系のレンズ枚数を削減できる。
【００１８】
また、前述の構成の４群ズームレンズにおいて、高変倍化を実現するためには第２群，第３群の変倍作用を強めることが必要である。
【００１９】
本発明は第３群を物体側の方が像側より強い曲率の正レンズとその像側に最も像側に配置した負レンズとを含む正または負のレンズ成分を配置することにより主点を第２群に近づけて変倍作用を強くしそれと共にこの第３群と第４群とで球面収差と軸上の色収差をバランス良く補正するようにしている。
【００２０】
また第３群の正または負のレンズ成分を正レンズと負レンズを接合して接合レンズにすれば枠に組み込む時の偏芯による性能の劣化を小さくでき安定した性能を確保できる。
【００２１】
また、第４群を正レンズとその像側の負レンズの隣接面が共に物体側に凹の面の第１隣接面を配置することにより第１群にて発生する球面収差を良好に補正すると共にワイドからテレにかけての軸外収差の変動を小さく抑えることができる。
【００２２】
また、第１隣接面を接合面にすれば高次収差の発生を抑えながら上記の球面収差と軸外収差とを一層良好に補正することが可能である。また前述のように接合すれば枠に組み込む時の偏芯による性能劣化を小さくでき安定した性能を確保できる。
【００２３】
また本発明のズームレンズの他の構成は、物体側から順に、正の屈折力を有する第１群と、負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、正の屈折力を有する第４群とよりなり、ワイド端からテレ端への変倍に際して、前記第１群は物体側へ移動し、前記第２群は前記第１群との間隔が増大するように移動し、前記第３群は前記第２群との間隔が狭くなるように移動し、前記第４群は前記第３群との間隔がワイド端よりもテレ端の方が狭くなるように移動し、前記第２群は物体側から順に、物体側に凸面を向けた負のメニスカスレンズを有する第１レンズ成分と、負レンズを含み全体が正の屈折力を有する第２レンズ成分と、負の屈折力を有する第３レンズ成分とよりなり、各々の成分が空気間隔を挟んで構成され、前記第３群は物体側から順に正レンズと負レンズとからなり、前記第４群は正レンズとその像側に負レンズとを有し正レンズと負レンズの向かい合う面の各々が共に物体側に凹面を向けた第１の隣接面を有し、前記第４群中の最も物体側のレンズが物体側に凸面を向けた正レンズであり光軸から離れるにしたがって屈折力が弱くなる非球面を有すことを特徴とする。
【００２４】
上記のズームレンズは、第４群中の最も物体側のレンズを物体側に凸面を向けた正レンズとし、このレンズに光軸から離れるにしたがって屈折力が弱くなる非球面を設けることにより第３群にて発生する球面収差を補正する作用を強めこれにより第３群を２枚のレンズのみにて構成することを可能にした。
【００２５】
また、本発明のズームレンズは、下記条件（１）を満足するようにすれば、中間焦点距離域での光学性能を良好に保ちつつ小型高変倍化を達成する上での適切な各群の動きとパワー配置にし得るので好ましい。
（１）４．３＜ｆ₁ ／｜ｆ₂ ｜＜６．３
ただし、ｆ₁ ，ｆ₂ は夫々第１群および第２群の焦点距離である。
【００２６】
条件（１）の下限の４．３を超えるとテレ端付近での全長を短くできるが第１群のレンズ径が大になりカメラとして小型化と高変倍化の達成が困難になる。また、条件（１）の上限の６．３を超えると第２群のパワーが強くなり先玉の径を小さくできるが中間主点距離域を含めて収差変動を抑えることが困難になる。
【００２７】
また、前述の構成の本発明のズームレンズは、高変倍比小型でありながら一層良好な性能を有するレンズ系を得るためには、第２群が下記条件（２）を満足することが望ましい。
（２）０．０７＜｜ｆ₂ ｜／ｆ_T ＜０．１６
ただし、ｆ_T はテレ端におけるズームレンズ全系の焦点距離である。
【００２８】
条件（２）の下限の０．０７を超えると高変倍化とテレ端での全長の短縮を図ることができるが、第２群で発生する収差が大になりすぎこれを補正するためには第２群のレンズ枚数を増加させなければならない。また、条件（２）の上限の０．１６を超えるとレンズ系の性能を保つためには好ましいが、テレ端での全長やレンズ径が大になりカメラとして小型化を達成できない。
【００２９】
本発明のズームレンズにおいて、第４群が前述の第１隣接面の他に第１隣接面と同様向かい合う面の各々が共に物体側に凹面を向けた第２隣接面を有することが望ましい。またこの面を接合面としても良い。
【００３０】
このように第２隣接面を設けることにより、第１隣接面を設けたことによる第３群で発生する球面収差を補正する作用とワイドからテレにかけての軸外収差の変動を抑制する作用が一層増大するので望ましい。
【００３１】
また、本発明のズームレンズにおいて、第３群の最も像側の正のレンズ成分を物体側より正レンズと負レンズとを接合した接合レンズにすれば、前述のように枠に組み込む時の偏芯による性能劣化を抑えることができる。
【００３２】
また第２群の正の第２レンズ成分を物体側より正レンズと負レンズを接合レンズにすれば同様の理由により好ましい。
【００３３】
本発明のズームレンズにおいて、第４群中に像側の面よりも屈折力の強い面を有するメニスカス状の空気レンズを設けることが望ましい。このような空気レンズを設けることにより、第３群にて発生する球面収差、コマ収差を変倍時の歪曲収差の変動を抑えながら良好に補正することができる。これにより第３群のレンズ枚数を削減することが可能になり、したがって、レンズ系の全長を短くししかも良好な光学性になし得る。
【００３４】
本発明のズームレンズにおいて、第２群と第３群の焦点距離が下記条件（３）を満足するようにすれば、レンズ系を安定した性能で高変倍化が可能である。
（３）０．３＜｜ｆ₂ ｜／ｆ₃ ＜０．４５
【００３５】
条件（３）の下限の０．３を超えると第２群での負のパワーが強くなりすぎてワイド付近での軸外収差の発生が大になると共にテレ端でのレンズ系の全長を短くすることが困難になる。また、条件（３）の上限を超えるとテレ端でのレンズ系の全長を短くすることが比較的容易であるがワイド端でのバックフォーカスを確保しながらの性能の維持が困難になる。
【００３６】
また、第４群の第１の隣接面の間隔ｄ₄₁が下記条件（４）を満足することが望ましい。
（４）０≦ｄ₄₁／ｈ≦０．０５
ただし、ｈは最大撮影像高である。上限の０．０５を超えると球面収差が補正不足になると共にワイド端からテレ端への変倍の際の軸外収差の変動が大になる。
【００３７】
また第４群の第２隣接面の間隔ｄ₄₂は次の条件（５）を満足することが望ましい。
（５）０≦ｄ₄₂／ｈ≦０．０５
上限の０．０５を超えると第１の隣接面を超えると同様に球面収差が補正不足になり、軸外収差の変動が大になる。
【００３８】
【発明の実施の形態】
次に本発明のズームレンズの実施の形態を下記データを有する各実施例にもとづいて説明する。

【００３９】

【００４０】

【００４１】

【００４２】
参考例
ｆ＝28.980〜63.962〜135.097 ，Ｆナンバー＝5.002 〜6.213 〜7.289
２ω＝76.3°〜36.3°〜17.7°
ｒ₁ ＝480.413 ｄ₁ ＝2.500 ｎ₁ ＝1.80518 ν₁ ＝25.43
ｒ₂ ＝75.765 ｄ₂ ＝5.158 ｎ₂ ＝1.62041 ν₂ ＝60.29
ｒ₃ ＝-181.527 ｄ₃ ＝0.200
ｒ₄ ＝45.476 ｄ₄ ＝3.900 ｎ₃ ＝1.74320 ν₃ ＝49.34
ｒ₅ ＝107.019 ｄ₅ ＝Ｄ₁ （可変）
ｒ₆ ＝97.657 ｄ₆ ＝1.400 ｎ₄ ＝1.83400 ν₄ ＝37.16
ｒ₇ ＝15.325 ｄ₇ ＝6.045
ｒ₈ ＝-43.900 ｄ₈ ＝1.100 ｎ₅ ＝1.63980 ν₅ ＝34.46
ｒ₉ ＝15.521 ｄ₉ ＝6.761 ｎ₆ ＝1.84666 ν₆ ＝23.78
ｒ₁₀＝-51.021 ｄ₁₀＝0.609
ｒ₁₁＝-28.428 ｄ₁₁＝1.000 ｎ₇ ＝1.77250 ν₇ ＝49.60
ｒ₁₂＝-1169.686 ｄ₁₂＝Ｄ₂ （可変）
ｒ₁₃＝∞（絞り）ｄ₁₃＝1.000
ｒ₁₄＝25.610 ｄ₁₄＝5.900 ｎ₈ ＝1.62280 ν₈ ＝57.05
ｒ₁₅＝-14.216 ｄ₁₅＝1.000 ｎ₉ ＝1.80610 ν₉ ＝40.92
ｒ₁₆＝-80.416 ｄ₁₆＝Ｄ₃ （可変）
ｒ₁₇＝26.571（非球面）ｄ₁₇＝7.591 ｎ₁₀＝1.48749 ν₁₀＝70.23
ｒ₁₈＝-22.631 （非球面）ｄ₁₈＝0.200
ｒ₁₉＝82.779 ｄ₁₉＝5.761 ｎ₁₁＝1.70154 ν₁₁＝41.24
ｒ₂₀＝-11.000 ｄ₂₀＝2.000 ｎ₁₂＝1.83400 ν₁₂＝37.16
ｒ₂₁＝23.314 ｄ₂₁＝0.964
ｒ₂₂＝58.001 ｄ₂₂＝2.000 ｎ₁₃＝1.84666 ν₁₃＝23.78
ｒ₂₃＝110.688
非球面係数
（第１７面）ｋ＝-1.8802 ，Ａ₄ ＝7.7264×10^-6 ，Ａ₆ ＝8.4057×10^-8
Ａ₈ ＝-1.7179 ×10^-11
（第１８面）ｋ＝-2.4219 ，Ａ₄ ＝-1.0470 ×10^-6 ，Ａ₆ ＝4.0776×10^-8
Ａ₈ ＝-8.5017 ×10^-10
ｆ 28.980 63.962 135.097
Ｄ₁ 0.950 14.387 28.677
Ｄ₂ 16.900 7.384 1.200
Ｄ₃ 6.609 2.941 0.950
ｆ_B 39.630 61.697 83.991
Ｌ（Ｔ）＝169.91 ，ＴＰ（Ｔ）＝1.26
ｆ_W ＝28.98 ，ｆ_T ＝135.1 ，ｆ_T ／ｆ_W ＝4.66 ，ｆ₁ ＝80.97
ｆ₂ ＝-16.24 ，ｆ₃ ＝46.23 ，ｆ₄ ＝61.35 ，ｆ₁ ／｜ｆ₂ ｜＝4.98
｜ｆ₂ ｜／ｆ_T ＝0.12 ，｜ｆ₂ ｜／ｆ₃ ＝0.35 ，ｈ＝21.633mm
ｄ₄₁₌0 ，ｄ₄₁／ｈ＝0
【００４３】

【００４４】

【００４５】

【００４６】

ただしｒ₁ ，ｒ₂ ，・・・は各レンズ面の曲率半径、ｄ₁ ，ｄ₂ ，・・・は各レンズの肉厚およびレンズ間隔、ｎ₁ ，ｎ₂ ，・・・は各レンズの屈折率、ν₁ ，ν₂ ，・・・は各レンズのアッベ数である。
【００４７】
実施例１は図１に示す通りの構成で、物体側より正の屈折力の第１群と負の屈折力の第２群と正の屈折力の第３群と正の屈折力の第４群とよりなり、ワイド端よりテレ端への変倍に際して第１群は物体側へ移動し、第２群は第１群との間隔を増大するように移動し、第３群は第２群との間隔が狭くなるように移動し、第４群は第３群との間隔が狭くなるように移動するズームレンズである。
【００４８】
また第２群は、物体側から物体側に凸面を向けた負のメニスカスレンズを有する第１レンズ成分と正の屈折力を有する第２レンズ成分（負レンズと正レンズとよりなり全体として負の屈折力を有するレンズ成分）と負の屈折力を有する第３レンズ成分（負レンズと正レンズとからなるレンズ成分）とからなり、絞りを挟んで第３群は物体側の面が像側の面より強い屈折力を有する正レンズとその像側に最も像側のレンズが負レンズであるレンズ成分（正レンズと負レンズとを接合した接合レンズ成分）とからなり、第４群は物体側に正レンズとその像側の負レンズを有しており（物体側から正レンズと負レンズよりなる第１レンズ成分を有しており）、この正レンズと負レンズの互いに向かい合っている両面が物体側に凹面を向けた第１の隣接面である。またこの第４群は前記第１レンズ成分と両凸レンズよりなるレンズ成分（第２レンズ成分）と正レンズと負のメニスカスレンズとよりなるレンズ成分（第３レンズ成分）を有している。この第３レンズ成分の正レンズと負のメニスカスレンズとの互いに向かい合った両面が物体側に凹面を向けた第２隣接面である。
【００４９】
この実施例１のズームレンズは条件（１）〜（５）のすべての条件を満足する。
【００５０】
実施例２は、図２に示す通りの構成で、第２群の負の第３レンズ成分が負レンズと正レンズを接合した接合レンズであり、また第４群の第１レンズ成分の正レンズと負レンズとが接合され、また第３レンズ成分の正レンズと負レンズとが接合され、したがって第１および第２隣接面がいずれも接合面である点で実施例１と相違する。
【００５１】
また実施例２は条件（１），（２），（３）を満足する。
【００５２】
実施例３は図３に示す通りで、第２群の第３レンズ成分が負レンズ１枚よりなり、第４群が正レンズよりなる第１レンズ成分と、正レンズと負レンズを接合した接合レンズの第２レンズ成分と正レンズと負レンズを接合した接合レンズとよりなり、第１，第２隣接面は接合面である点で実施例１と相違する。
【００５３】
この実施例３は条件（１），（２），（３）を満足する。
【００５４】
実施例４は図４に示す通りの構成で、実施例３と同じ構成のズームレンズである。
【００５５】
この実施例４は条件（１），（２），（３）を満足する。
【００５６】
参考例は図５に示す通りの構成で、第２群が負のメニスカスレンズの第１レンズ成分と負レンズと正レンズとを接合した接合レンズの第２レンズ成分と負レンズの第３レンズ成分とよりなり、第３群が正レンズと負レンズを接合レンズよりなるレンズ成分のみつまり正レンズと負レンズのみからなり、第４群が正レンズの第１レンズ成分と正レンズと負レンズを接合した接合レンズの第２レンズ成分と正のメニスカスレンズの第３レンズ成分とよりなる。また第４群の第１レンズ成分（両凸レンズ）が非球面レンズである。
【００５７】
この参考例は条件（１），（２），（３）を満足する。
【００５８】
この参考例は非球面を用いておりこれによって極めて少ないレンズ枚数で良好な性能を有するズームレンズを実現したものである。
【００５９】
実施例６〜９は夫々図６〜９に示す通りで、実施例３と類似の構成のズームレンズである。
【００６０】
これら実施例は、いずれも条件（１），（２），（３）を満足する。
以上述べた実施例１〜９の収差状況は図１０〜１８に示す通りで、いずれも良好な光学性能を有する。
尚収差図中、上段はワイド端、中段は中間焦点距離、下段はテレ端に対するものである。
【００６１】
本発明の参考例に設けられている非球面の形状は、光軸方向をｘ軸、光軸に直角な方向をｙ軸とした時、下記の式にて表わされる。
ｘ＝（ｙ²／ｒ）／［１＋｛１−（１＋ｋ）（ｙ／ｒ）²｝^1/2］
＋Ａ₄ｙ⁴＋Ａ₆ｙ⁶＋Ａ₈ｙ⁸＋・・・
ただし、ｒは基準球面の曲率半径、ｋ、Ａ₄、Ａ₆、Ａ₈・・・は非球面係数である。
【００６２】
次に述べるズームレンズも本発明の目的を達成する。
【００６３】
（１）特許請求の範囲の請求項１又は２に記載するズームレンズで下記条件（２）を満足することを特徴とする小型高変倍広角ズームレンズ。
（２）０．０７＜｜ｆ₂ ｜／ｆ_T ＜０．１６
【００６４】
（２）特許請求の範囲の請求項１又は３あるいは前記の（１）の項に記載するズームレンズで、更に物体側より正レンズと負レンズを含み互いに向かい合う面がいずれも物体側に凹面を向けた第２の隣接面である小型高変倍広角ズームレンズ。
【００６５】
（３）特許請求の範囲の請求項１又は２あるいは前記の（１）又は（２）の項のズームレンズで、第３群の最も像側が負レンズである正の屈折力のレンズ成分が物体側から順に正レンズと負レンズからなる接合レンズである小型高変倍広角ズームレンズ。
【００６６】
（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），（２）又は（３）の項に記載するズームレンズで、第２群中の第２レンズ成分が物体側から順に負レンズと正レンズからなる小型高変倍広角ズームレンズ。
【００６７】
（５）前記の（４）の項に記載するズームレンズで、第２群中の第２レンズ成分の負レンズと正レンズが接合された接合レンズである小型高変倍広角ズームレンズ。
【００６８】
（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），（２），（３），（４）又は（５）の項に記載するズームレンズで、第２群中の第３レンズ成分が負レンズ１枚よりなる小型高変倍広角ズームレンズ。
【００６９】
（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），（２），（３），（４），（５）又は（６）の項に記載するズームレンズで、第４群中に像側の面よりも物体側の面がより強い屈折力を有するメニスカス形状の空気レンズを有する小型高変倍広角ズームレンズ。
【００７０】
（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），（２），（３），（４），（５）又は（６）の項に記載するズームレンズで、下記条件（３）を満足する小型高変倍広角ズームレンズ。
（３）０．３＜｜ｆ₂ ｜／ｆ₃ ＜０．４５
【００７１】
（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），（２），（３），（４），（５），（６），（７）又は（８）の項に記載するズームレンズで、下記条件（４）を満足する小型高変倍広角ズームレンズ。
（４）０≦ｄ₄₂／ｈ≦０．０５
【００７２】
（１０）前記の（２）の項に記載するズームレンズで、下記条件（５）を満足する小型高変倍広角ズームレンズ。
（５）０≦ｄ₄₂／ｈ≦０．０５
【００７３】
（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），（２），（３），（４），（５），（６），（７）又は（８）の項に記載するズームレンズで、第１隣接面が接合面である小型高変倍広角ズームレンズ。
【００７４】
（１２）前記の（２）の項に記載するズームレンズで、第２隣接面が接合面である小型高変倍広角ズームレンズ。
【００７５】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１）又は（１２）の項に記載するズームレンズで、変倍比が４を超える小型高変倍広角ズームレンズ。
【００７６】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１）又は（１２）の項に記載するズームレンズで、変倍比が４．６を超える小型高変倍広角ズームレンズ。
【００７７】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１），（１２），（１３）あるいは（１４）の項に記載するズームレンズで、望遠比が１．３以下である小型高変倍広角ズームレンズ。
【００７８】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１），（１２），（１３）あるいは（１４）の項に記載するズームレンズで、望遠比が１．２６以下である小型高変倍広角ズームレンズ。
【００７９】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１），（１２），（１３），（１４），（１５）又は（１６）の項に記載するズームレンズで、画角２ωが６５°を超える小型高変倍広角ズームレンズ。
【００８０】
（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），（２），（３），（４），（５），（６），（７），（８），（９），（１０），（１１），（１２），（１３），（１４），（１５）又は（１６）の項に記載するズームレンズで、画角２ωが７５°を超える小型高変倍広角ズームレンズ。
【００８１】
【発明の効果】
本発明によれば、変倍比が４を超える高変倍で、テレ端での望遠比が１．３で全長が短く、ワイド端での画角が６５°以上の広角で変倍域全体で良好な性能の小型高変倍広角ズームレンズを実現し得る。
【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】本発明の実施例８の構成を示す図
【図９】本発明の実施例９の構成を示す図
【図１０】本発明の実施例１の収差曲線図
【図１１】本発明の実施例２の収差曲線図
【図１２】本発明の実施例３の収差曲線図
【図１３】本発明の実施例４の収差曲線図
【図１４】本発明の実施例５の収差曲線図
【図１５】本発明の実施例６の収差曲線図
【図１６】本発明の実施例７の収差曲線図
【図１７】本発明の実施例８の収差曲線図
【図１８】本発明の実施例９の収差曲線図[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a compact high variable magnification wide-angle lens.
[0002]
[Prior art]
As a zoom lens that is highly variable and that can achieve miniaturization, a lens system that has positive, negative, positive, and positive groups in order from the object side, and performs zooming by moving each group is effective. It has been known for some time.
[0003]
In this manner, in order from the object side, as a conventional example of a zoom lens composed of a positive group, a negative group, a positive group, and a positive group, the lens system of the first and second examples of Japanese Patent Laid-Open No. 58-202418, US A lens system according to first, second and third embodiments of Japanese Patent No. 4256381 and a lens system of first and second embodiments of Japanese Patent Laid-Open No. 10-133111 are known. These zoom lenses are lens systems in which the angle of view 2ω at the wide-angle end exceeds 65 °, but the zoom ratio does not reach 4 times and cannot be said to be a zoom lens with a high zoom ratio.
[0004]
Further, as another conventional example of a zoom lens composed of positive, negative, positive, and positive groups, the lens system of the first and second embodiments described in Japanese Patent Laid-Open No. 60-26312, A lens system according to first and second embodiments disclosed in Japanese Patent No. -45641 and a lens system according to first and second embodiments disclosed in Japanese Patent Laid-Open No. 56-150717 are known. However, these lens systems have a narrow angle of view with a field angle 2ω at the wide-angle end of 45 ° or less.
[0005]
Furthermore, as other conventional examples of zoom lenses composed of positive, negative, positive, and positive groups, lens systems of Examples 4 to 8 of U.S. Pat. No. 4,256,381, No. 4 of U.S. Pat. No. 4,299,454. Examples include the lens systems of Examples 1 to 4 of JP-A-63-70819. These lens systems have a zoom ratio of more than 4, but the telephoto ratio at the telephoto end is 1.4, and the total length of the lens system is long and not small.
[0006]
[Problems to be solved by the invention]
The present invention is a four-group configuration of positive, negative, positive, and positive groups, with a high zoom ratio exceeding 4 and a small lens diameter, with a telephoto ratio of 1.3 or less at the telephoto end. And a zoom lens having good optical properties in the entire region from the wide end to the tele end where the angle of view 2ω exceeds 65 °.
[0007]
[Means for Solving the Problems]
    The zoom lens of the present invention has, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a positive refractive power. The first group moves to the object side, and the second group moves to increase the distance from the first group when zooming from the wide end to the tele end. Moves so as to narrow the distance from the second group, the fourth group moves so that the distance from the third group becomes narrower at the tele end than at the wide end, and the second group moves from the object side. In order, the first lens component having a negative meniscus lens having a convex surface facing the object side, the second lens component including a negative lens and having a positive refractive power, and the third lens component having a negative refractive power, The third group is a positive lens whose surface on the object side has a stronger refractive power than the surface on the image side, and a negative lens on the image side closest to the image side. Overall positiveOr negativeThe fourth lens unit has a positive lens and a negative lens on the image side thereof, and the surfaces facing the positive lens and the negative lens both have concave surfaces facing the object side. It has an adjacent surface.
[0008]
Here, the lens component is composed of one or a plurality of lenses and has the function and role as a single lens as a whole. May be arranged separately.
[0009]
As zoom lenses from wide angles increase in magnification, it is difficult to maintain good optical performance due to large variations in chromatic aberration of the image plane and magnification, not only at the wide end and tele end, but also in the intermediate focal length range. become. Therefore, it is important to appropriately select the movement and power of each group for a high zoom ratio.
[0010]
Therefore, the present invention is composed of positive, negative, positive and positive groups in order from the object side as described above, and the first group moves to the object side upon zooming from the wide end to the tele end, and the second group. Moves so that the distance from the first group increases, the third group moves so that the distance from the second group becomes narrow, and the fourth group moves the distance from the third group from the wide end to the tele end. I tried to narrow it.
[0011]
Thereby, the power distribution is such that off-axis aberrations mainly occurring on the wide side can be corrected well with the positive power of the first group and the negative power of the second group arranged on the object side of the aperture stop, Also, on the tele side, the first group is positive power so that the total length at the tele end is shortened, and further, the negative power of the second group and the positive power of the third group and the fourth group are brought close to each other. A power distribution that can correct spherical aberration and coma well is adopted. Further, when the third lens group and the fourth lens group are moved to the object side at the time of zooming from the wide end to the telephoto end, the spherical aberration and coma aberration correcting action becomes more effective.
[0012]
In addition, the four-group zoom lens having the above-described configuration can be highly zoomed in by increasing the zooming effect by changing the distance between the second group and the third group. It is necessary to increase power. When the power of the second lens group is increased in this way, distortion at the wide end mainly deteriorates, and image plane variation at the time of zooming and chromatic aberration of magnification are caused.
[0013]
The present invention provides a first lens component having a negative meniscus lens having a convex surface facing the object side in order from the object side to the object side, a positive second lens component, and a positive third lens component. By adopting a sandwiched arrangement, it is possible to increase the power of the second lens group while maintaining good distortion at the wide end and also maintaining small variations in image plane and magnification chromatic aberration during zooming. Made possible.
[0014]
That is, it is possible to effectively correct positive distortion occurring in the first group by including a negative meniscus lens having a strong convex power on the object side in the first lens component of the second group. However, if the power is increased too much, fluctuations during zooming of astigmatism, coma aberration, and chromatic aberration of magnification become large. Therefore, the power of the negative meniscus lens in the first lens component is shared by including the negative lens in the positive second lens component, thereby changing the astigmatism, coma aberration, and chromatic aberration of magnification at the time of zooming. The chromatic aberration of magnification mainly near the wide end and the longitudinal chromatic aberration near the tele end can be favorably corrected by the positive lens in the second lens component while reducing the size.
[0015]
The balance between the remaining chromatic aberration, spherical aberration, and coma aberration can be controlled by the negative third lens component. Then, the above three lens components are arranged independently with an air gap therebetween, so that the aberration of the lens system can be secured satisfactorily.
[0016]
It is also possible to configure the second lens component with two lenses, a negative lens and a positive lens, and the third lens component with one lens, thereby reducing the number of lenses in the lens system. Can be reduced in cost and weight. In addition, by joining the negative lens and the positive lens to form a cemented lens as the second lens component, it is possible to reduce performance degradation due to eccentricity when incorporated in the frame, and to secure stable performance.
[0017]
Further, even if the first lens component of the second group is composed of a single negative meniscus lens, it is possible to suppress the deterioration of aberration, and it can be composed of only one lens. The number of sheets can be reduced.
[0018]
Further, in the four-group zoom lens having the above-described configuration, it is necessary to increase the zooming action of the second group and the third group in order to realize high zooming.
[0019]
    The present invention includes a positive lens that includes a positive lens having a curvature that is stronger on the object side than on the image side and a negative lens disposed closest to the image side on the image side.Or negativeBy arranging the lens components, the principal point is brought closer to the second group to increase the zooming action, and the third group and the fourth group correct spherical aberration and axial chromatic aberration in a balanced manner. Yes.
[0020]
    The third group positiveOr negativeIf a positive lens and a negative lens are cemented to form a cemented lens, the deterioration in performance due to eccentricity when incorporated into the frame can be reduced, and stable performance can be secured.
[0021]
Further, by arranging the first adjacent surface which is a concave surface on the object side of the positive lens and the adjacent surface of the negative lens on the image side in the fourth group, spherical aberration generated in the first group is corrected well. At the same time, fluctuations in off-axis aberrations from wide to telephoto can be reduced.
[0022]
Further, if the first adjacent surface is a cemented surface, it is possible to correct the spherical aberration and off-axis aberration more satisfactorily while suppressing the occurrence of high-order aberrations. Moreover, if it joins as mentioned above, the performance degradation by eccentricity at the time of incorporating in a frame can be made small, and the stable performance can be ensured.
[0023]
According to another configuration of the zoom lens of the present invention, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, The fourth group has a positive refractive power, and when zooming from the wide end to the tele end, the first group moves to the object side, and the second group has an increased distance from the first group. The third group moves so that the distance from the second group becomes narrower, and the fourth group moves so that the distance from the third group becomes narrower at the tele end than at the wide end. The second lens unit sequentially includes, from the object side, a first lens component having a negative meniscus lens having a convex surface facing the object side, and a second lens component including a negative lens and having a positive refractive power as a whole. , And a third lens component having negative refractive power, each component being configured with an air gap in between, Is composed of a positive lens and a negative lens in order from the object side, and the fourth group has a positive lens and a negative lens on the image side thereof, and each of the facing surfaces of the positive lens and the negative lens has a concave surface facing the object side. A first abutment surface, and the lens closest to the object side in the fourth group is a positive lens having a convex surface facing the object side, and has an aspheric surface whose refractive power decreases with increasing distance from the optical axis. It is characterized by.
[0024]
In the zoom lens described above, the lens on the most object side in the fourth lens group is a positive lens having a convex surface directed toward the object side, and this lens is provided with an aspheric surface whose refractive power becomes weaker as the distance from the optical axis increases. The action of correcting the spherical aberration generated in the group is strengthened, and this makes it possible to configure the third group with only two lenses.
[0025]
Further, if the zoom lens of the present invention satisfies the following condition (1), each group suitable for achieving small size and high zoom ratio while maintaining good optical performance in the intermediate focal length region. This is preferable because the movement and power arrangement can be achieved.
(1) 4.3 <f₁ / | F₂ | <6.3
Where f₁ , F₂ Are the focal lengths of the first group and the second group, respectively.
[0026]
If the lower limit of 4.3 of the condition (1) is exceeded, the total length near the telephoto end can be shortened, but the lens diameter of the first group becomes large and it becomes difficult to achieve miniaturization and high zoom ratio as a camera. If the upper limit of 6.3 of condition (1) is exceeded, the power of the second lens group becomes strong and the diameter of the front lens can be reduced, but it is difficult to suppress aberration fluctuations including the intermediate principal point distance region.
[0027]
In addition, the zoom lens of the present invention having the above-described configuration is preferably configured such that the second lens group satisfies the following condition (2) in order to obtain a lens system having a higher zoom ratio and a smaller size. .
(2) 0.07 <| f₂ | / F_T <0.16
Where f_T Is the focal length of the entire zoom lens system at the telephoto end.
[0028]
If the lower limit of 0.07 of the condition (2) is exceeded, it is possible to increase the zoom ratio and shorten the total length at the telephoto end. However, in order to correct this, the aberration generated in the second group becomes too large. Needs to increase the number of lenses in the second group. If the upper limit of 0.16 of the condition (2) is exceeded, it is preferable to maintain the performance of the lens system. However, the total length and lens diameter at the tele end are increased, and the camera cannot be downsized.
[0029]
In the zoom lens according to the present invention, it is desirable that the fourth group has a second adjacent surface having a concave surface facing the object side in addition to the first adjacent surface described above. Further, this surface may be used as a bonding surface.
[0030]
By providing the second adjacent surface in this way, the effect of correcting the spherical aberration generated in the third group due to the provision of the first adjacent surface and the effect of suppressing the fluctuation of off-axis aberration from wide to telephoto are further increased. This is desirable because it increases.
[0031]
In the zoom lens according to the present invention, if the positive lens component on the most image side in the third group is a cemented lens in which a positive lens and a negative lens are cemented from the object side, the deviation when incorporated in the frame as described above. Performance degradation due to the wick can be suppressed.
[0032]
For the same reason, it is preferable to use a positive second lens component of the second group as a cemented lens from the object side.
[0033]
In the zoom lens of the present invention, it is desirable to provide a meniscus air lens having a surface having a refractive power stronger than that of the image side surface in the fourth lens group. By providing such an air lens, spherical aberration and coma generated in the third group can be corrected well while suppressing fluctuations in distortion during zooming. As a result, the number of lenses in the third group can be reduced, and therefore the overall length of the lens system can be shortened and good optical performance can be achieved.
[0034]
In the zoom lens according to the present invention, if the focal lengths of the second group and the third group satisfy the following condition (3), the lens system can achieve high zooming with stable performance.
(3) 0.3 <| f₂ | / F_Three <0.45
[0035]
Exceeding the lower limit of 0.3 of condition (3), the negative power in the second lens unit becomes too strong, causing off-axis aberrations in the vicinity of the wide angle, and shortening the total length of the lens system at the telephoto end. It becomes difficult to do. If the upper limit of the condition (3) is exceeded, it is relatively easy to shorten the total length of the lens system at the tele end, but it becomes difficult to maintain performance while ensuring the back focus at the wide end.
[0036]
The distance d between the first adjacent surfaces of the fourth group₄₁Preferably satisfies the following condition (4).
(4) 0 ≦ d₄₁/H≦0.05
Here, h is the maximum photographed image height. When the upper limit of 0.05 is exceeded, the spherical aberration becomes insufficiently corrected and the fluctuation of off-axis aberrations during zooming from the wide end to the tele end becomes large.
[0037]
The distance d between the second adjacent surfaces of the fourth group₄₂It is desirable to satisfy the following condition (5).
(5) 0 ≦ d₄₂/H≦0.05
When the upper limit of 0.05 is exceeded, the spherical aberration is undercorrected as well as exceeding the first adjacent surface, and the fluctuation of off-axis aberration becomes large.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the zoom lens of the present invention will be described based on each example having the following data.

[0039]

[0040]

[0041]

[0042]
Reference example
f = 28.980-63.962-135.097, F number = 5.002-6.213-7.289
2ω = 76.3 ° -36.3 ° -17.7 °
r₁ = 480.413 d₁ = 2.500 n₁ = 1.80518 ν₁ = 25.43
r₂ = 75.765 d₂ = 5.158 n₂ = 1.62041 ν₂ = 60.29
r_Three = -181.527 d_Three = 0.200
r_Four = 45.476 d_Four = 3.900 n_Three = 1.74320 ν_Three = 49.34
r_Five = 107.019 d_Five = D₁ (variable)
r₆ = 97.657 d₆ = 1.400 n_Four = 1.83400 ν_Four = 37.16
r₇ = 15.325 d₇ = 6.045
r₈ = -43.900 d₈ = 1.100 n_Five = 1.63980 ν_Five = 34.46
r₉ = 15.521 d₉ = 6.761 n₆ = 1.84666 ν₆ = 23.78
r_Ten= -51.021 d_Ten= 0.609
r₁₁= -28.428 d₁₁= 1.000 n₇ = 1.77250 ν₇ = 49.60
r₁₂= -1169.686 d₁₂= D₂ (variable)
r₁₃= ∞ (aperture) d₁₃= 1.000
r₁₄= 25.610 d₁₄= 5.900 n₈ = 1.62280 ν₈ = 57.05
r₁₅= -14.216 d₁₅= 1.000 n₉ = 1.80610 ν₉ = 40.92
r₁₆= -80.416 d₁₆= D_Three (variable)
r₁₇= 26.571 (aspherical surface) d₁₇= 7.591 n_Ten= 1.48749 ν_Ten= 70.23
r₁₈= -22.631 (Aspherical surface) d₁₈= 0.200
r₁₉= 82.779 d₁₉= 5.761 n₁₁= 1.70154 ν₁₁= 41.24
r₂₀= -11.000 d₂₀= 2.000 n₁₂= 1.83400 ν₁₂= 37.16
r_{twenty one}= 23.314 d_{twenty one}= 0.964
r_{twenty two}= 58.001 d_{twenty two}= 2.000 n₁₃= 1.84666 ν₁₃= 23.78
r_{twenty three}= 110.688
Aspheric coefficient
(Seventeenth surface) k = -1.8802, A_Four = 7.7264 × 10^-6  , A₆ = 8.4057 × 10^-8
            A₈ = -1.7179 x10^-11
(18th surface) k = -2.4219, A_Four = -1.0470 x10^-6  , A₆ = 4.0776 × 10^-8
            A₈ = -8.5017 x10^-Ten
f 28.980 63.962 135.097
D₁           0.950 14.387 28.677
D₂           16.900 7.384 1.200
D_Three           6.609 2.941 0.950
f_B           39.630 61.697 83.991
L (T) = 169.91, TP (T) = 1.26
f_W = 28.98, f_T = 135.1, f_T / F_W = 4.66, f₁ = 80.97
f₂ = -16.24, f_Three = 46.23, f_Four = 61.35, f₁ / | F₂ ｜＝ 4.98
｜ f₂ | / F_T = 0.12, | f₂ | / F_Three = 0.35, h = 21.633mm
d_{41 =}0, d₄₁/ H = 0
[0043]

[0044]

[0045]

[0046]

Where r₁ , R₂ , ... are the radius of curvature of each lens surface, d₁ , D₂ , ... are the thickness of each lens and the lens interval, n₁ , N₂ , ... are the refractive indices of each lens, ν₁ , Ν₂ , ... are Abbe numbers of each lens.
[0047]
The first embodiment is configured as shown in FIG. 1, and from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. The first group moves to the object side upon zooming from the wide end to the tele end, the second group moves to increase the distance from the first group, and the third group is the second group. The fourth lens group is a zoom lens that moves so that the distance between the third lens group and the third lens group decreases.
[0048]
    The second group includes a first lens component having a negative meniscus lens having a convex surface from the object side toward the object side and a second lens component having a positive refractive power (a negative lens and a positive lens as a whole are negative. Lens component having a refractive power) and a third lens component having a negative refractive power (a lens component made up of a negative lens and a positive lens). A positive lens with a refractive power stronger than the surface and the lens closest to the image side is the negative lens.A certain lens componentThe fourth lens group has a positive lens on the object side and a negative lens on the image side (consisting of a positive lens and a negative lens from the object side). The first lens component has a first lens component), and both surfaces of the positive lens and the negative lens facing each other are first adjacent surfaces having a concave surface facing the object side. The fourth group includes a lens component (second lens component) composed of the first lens component and a biconvex lens, and a lens component (third lens component) composed of a positive lens and a negative meniscus lens. The opposite surfaces of the positive lens and negative meniscus lens of the third lens component are the second adjacent surfaces with the concave surface facing the object side.
[0049]
The zoom lens of Example 1 satisfies all the conditions (1) to (5).
[0050]
In the second embodiment, the negative third lens component of the second group is a cemented lens in which a negative lens and a positive lens are cemented, and the positive lens of the first lens component of the fourth group is configured as shown in FIG. And the negative lens are cemented, and the positive lens and the negative lens of the third lens component are cemented, so that the first and second adjacent surfaces are both cemented surfaces.
[0051]
In Example 2, the conditions (1), (2), and (3) are satisfied.
[0052]
In Example 3, as shown in FIG. 3, the third lens component of the second group is composed of one negative lens, the first lens component of which the fourth group is composed of a positive lens, and the cemented structure in which the positive lens and the negative lens are cemented together. The second lens component of the lens and a cemented lens obtained by cementing a positive lens and a negative lens are different from the first embodiment in that the first and second adjacent surfaces are cemented surfaces.
[0053]
This Example 3 satisfies the conditions (1), (2), and (3).
[0054]
Example 4 is a zoom lens having the same configuration as that of Example 3 as shown in FIG.
[0055]
This Example 4 satisfies the conditions (1), (2), and (3).
[0056]
    Reference example5 has a configuration as shown in FIG. 5, and the second lens unit includes a first lens component of a negative meniscus lens, a second lens component of a cemented lens in which a negative lens and a positive lens are cemented, and a third lens component of the negative lens. The third group is composed of only a lens component composed of a positive lens and a negative lens, that is, a positive lens and a negative lens, and the fourth group is composed of a first lens component of the positive lens, a positive lens, and a negative lens. It consists of the second lens component of the lens and the third lens component of the positive meniscus lens. The first lens component (biconvex lens) of the fourth group is an aspheric lens.
[0057]
    thisReference exampleSatisfies the conditions (1), (2), and (3).
[0058]
    thisReference exampleUses an aspherical surface, thereby realizing a zoom lens having good performance with a very small number of lenses.
[0059]
Examples 6 to 9 are zoom lenses having configurations similar to those of Example 3 as shown in FIGS.
[0060]
These examples all satisfy the conditions (1), (2), and (3).
The aberration states of Examples 1 to 9 described above are as shown in FIGS. 10 to 18 and all have good optical performance.
In the aberration diagrams, the upper row is for the wide end, the middle row is for the intermediate focal length, and the lower row is for the telephoto end.
[0061]
    Of the present inventionReference exampleThe shape of the aspherical surface provided in is expressed by the following equation when the optical axis direction is the x axis and the direction perpendicular to the optical axis is the y axis.
    x = (y²/ R) / [1+ {1- (1 + k) (y / r)²}^1/2]
            + A_Foury^Four+ A₆y⁶+ A₈y⁸+ ...
    Where r is the radius of curvature of the reference sphere, k, A_Four, A₆, A₈... Are aspherical coefficients.
[0062]
The zoom lens described below also achieves the object of the present invention.
[0063]
(1) A compact high-magnification wide-angle zoom lens that satisfies the following condition (2) in the zoom lens according to claim 1 or 2.
(2) 0.07 <| f₂ | / F_T <0.16
[0064]
(2) In the zoom lens according to claim 1 or 3 of the claims or the above-mentioned item (1), both surfaces including a positive lens and a negative lens from the object side and facing each other are concave on the object side. A small, high-magnification, wide-angle zoom lens that faces the second adjacent surface.
[0065]
(3) In the zoom lens according to claim 1 or 2 in the claims, or the zoom lens according to (1) or (2), the lens component having a positive refractive power whose most image side in the third group is a negative lens is an object. A compact high-magnification wide-angle zoom lens that is a cemented lens consisting of a positive lens and a negative lens in order from the side.
[0066]
(4) In the zoom lens according to claim 1, 2 or 3, or (1), (2) or (3), the second lens component in the second group is on the object side. A compact, high-magnification, wide-angle zoom lens consisting of a negative lens and a positive lens.
[0067]
(5) A compact high-magnification wide-angle zoom lens that is a cemented lens in which the negative lens and the positive lens of the second lens component in the second group are cemented in the zoom lens described in the above section (4).
[0068]
(6) The zoom lens according to claim 1, 2 or 3, or (1), (2), (3), (4) or (5), wherein A compact high-magnification wide-angle zoom lens whose third lens component consists of a single negative lens.
[0069]
(7) A zoom lens according to claim 1, 2 or 3, or (1), (2), (3), (4), (5) or (6), A compact high-magnification wide-angle zoom lens having a meniscus air lens having a refractive power stronger on the object side than on the image side.
[0070]
(8) A zoom lens according to claim 1, 2 or 3, or (1), (2), (3), (4), (5) or (6), A compact high-magnification wide-angle zoom lens that satisfies the following condition (3).
(3) 0.3 <| f₂ | / F_Three <0.45
[0071]
(9) Claim 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7) or (8) A compact high-magnification wide-angle zoom lens that satisfies the following condition (4):
(4) 0 ≦ d₄₂/H≦0.05
[0072]
(10) A compact high-magnification wide-angle zoom lens satisfying the following condition (5), according to the zoom lens described in (2) above.
(5) 0 ≦ d₄₂/H≦0.05
[0073]
(11) Claims 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7) or (8) A small high-magnification / wide-angle zoom lens, wherein the first adjacent surface is a cemented surface.
[0074]
(12) The zoom lens according to (2), wherein the second adjacent surface is a cemented surface.
[0075]
(13) Claims 1, 2 or 3 of the claims or (1), (2), (3), (4), (5), (6), (7), (8), (9) A zoom lens described in the item (10), (11) or (12), wherein the zoom ratio is a high-magnification zoom lens with a zoom ratio exceeding 4.
[0076]
(14) Claims 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7), (8), (9) A zoom lens described in the item (10), (11) or (12), wherein the zoom ratio is a high-magnification wide-angle zoom lens with a zoom ratio exceeding 4.6.
[0077]
(15) Claims 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7), (8), (9) A zoom lens according to (10), (11), (12), (13) or (14), wherein the telephoto ratio is 1.3 or less.
[0078]
(16) Claims 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7), (8), (9) A zoom lens according to (10), (11), (12), (13) or (14), wherein the telephoto ratio is 1.26 or less.
[0079]
(17) Claims 1, 2 or 3 of the claims or the above (1), (2), (3), (4), (5), (6), (7), (8), The zoom lens according to (9), (10), (11), (12), (13), (14), (15) or (16), and having a small and high field angle 2ω exceeding 65 ° Variable magnification wide-angle zoom lens.
[0080]
(18) Claims 1, 2 or 3 of the claims or (1), (2), (3), (4), (5), (6), (7), (8), The zoom lens according to (9), (10), (11), (12), (13), (14), (15), or (16), and a small and high zoom lens with an angle of view 2ω exceeding 75 ° Variable magnification wide-angle zoom lens.
[0081]
【The invention's effect】
According to the present invention, the zoom ratio is a high zoom ratio exceeding 4; the telephoto ratio at the tele end is 1.3; the total length is short; the wide angle of view at the wide end is 65 ° or more; Thus, it is possible to realize a small high-magnification wide-angle zoom lens with good performance.
[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. 4 is a diagram showing a configuration of a fourth embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a fifth embodiment of the present invention.
FIG. 6 is a diagram showing a configuration of a sixth embodiment of the present invention.
FIG. 7 is a diagram showing a configuration of a seventh embodiment of the present invention.
FIG. 8 is a diagram showing a configuration of an eighth embodiment of the present invention.
FIG. 9 is a diagram showing a configuration of a ninth embodiment of the present invention.
FIG. 10 is an aberration curve diagram of Example 1 of the present invention.
FIG. 11 is an aberration curve diagram of Example 2 of the present invention.
FIG. 12 is an aberration curve diagram of Example 3 of the present invention.
FIG. 13 is an aberration curve diagram of Example 4 of the present invention.
FIG. 14 is an aberration curve diagram of Example 5 of the present invention.
FIG. 15 is an aberration curve diagram of Example 6 of the present invention.
FIG. 16 is an aberration curve diagram of Example 7 of the present invention.
FIG. 17 is an aberration curve diagram of Example 8 of the present invention.
FIG. 18 is an aberration curve diagram of Example 9 of the present invention.

Claims

In order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. When zooming from the wide end to the tele end, the first group moves to the object side, the second group moves so as to increase the distance from the first group, and the third group is the distance from the second group. The fourth group moves so that the distance from the third group is narrower at the tele end than at the wide end, and the second group has a convex surface on the object side in order from the object side. A negative meniscus lens having a negative refractive power composed of a first lens component, a negative lens and a positive lens, and a second lens component having a positive refractive power and a negative lens and a positive lens or one negative lens. It is composed of a third lens component, and each component is configured with an air gap in between, and the third group has an object side surface on the image side A positive lens having a refractive power stronger than that of the surface, a positive lens on the image side, and a lens component having a positive or negative refractive power as a whole. A negative lens on the image side, each of the opposing surfaces of the positive lens and the negative lens has a first adjacent surface with a concave surface facing the object side, and the fourth group includes the first lens Further, the surfaces adjacent to each other including the positive lens and the negative lens from the object side have a second adjacent surface with the concave surface facing the object side, and the following conditions (1) and (4) ) And (5) satisfying (5).
(1) 4.3 <f ₁ / | f ₂ | <6.3
(4) 0 ≦ d ₄₁ /h≦0.05
(5) 0 ≦ d ₄₂ /h≦0.05
Where f ₁ and f ₂ are the focal lengths of the first group and the second group, respectively, d ₄₁ is the distance between the first adjacent surfaces of the fourth group, d ₄₂ is the distance between the second adjacent surfaces of the fourth group, h is the maximum photographed image height.

2. The compact high variable magnification wide-angle zoom lens according to claim 1, wherein the following condition (2) is satisfied.
(2) 0.07 <| f ₂ | / f _T <0.16
Here, f ₂ is the focal length of the second group, and f _T is the focal length of the entire zoom lens system at the telephoto end.

In order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. When zooming from the wide end to the tele end, the first group moves to the object side, the second group moves so as to increase the distance from the first group, and the third group is the distance from the second group. The fourth group moves so that the distance from the third group is narrower at the tele end than at the wide end, and the second group has a convex surface on the object side in order from the object side. A negative meniscus lens having a negative refractive power composed of a first lens component, a negative lens and a positive lens, and a second lens component having a positive refractive power and a negative lens and a positive lens or one negative lens. It is composed of a third lens component, and each component is configured with an air gap in between, and the third group has an object side surface on the image side A positive lens having a refractive power stronger than the surface, a positive lens on the image side, and a lens component having a positive or negative refractive power as a whole, and a lens having the positive or negative refractive power The component is a cemented lens composed of a positive lens and a negative lens in order from the object side, and the fourth group includes a positive lens and a negative lens on the image side, and the surfaces facing the positive lens and the negative lens are both A first adjacent surface having a concave surface facing the object side, and the fourth group is located on the image side of the first adjacent surface, and further includes a positive lens and a negative lens on the object side, and faces each other. Have a second adjacent surface with the concave surface facing the object side and satisfy the following conditions (4) and (5).
(4) 0 ≦ d ₄₁ /h≦0.05
(5) 0 ≦ d ₄₂ /h≦0.05
Here, d ₄₁ is the distance between the first adjacent surfaces of the fourth group, d ₄₂ is the distance between the second adjacent surfaces of the fourth group, and h is the maximum photographed image height.

In order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. When zooming from the wide end to the tele end, the first group moves to the object side, the second group moves so as to increase the distance from the first group, and the third group is the distance from the second group. The fourth group moves so that the distance from the third group is narrower at the tele end than at the wide end, and the second group has a convex surface on the object side in order from the object side. A negative meniscus lens having a negative refractive power composed of a first lens component, a negative lens and a positive lens, and a second lens component having a positive refractive power and a negative lens and a positive lens or one negative lens. Each of the components is formed with an air gap in between, and the negative lens of the second lens component is And a positive lens in which the third lens unit has a refractive power stronger than the surface on the object side than the surface on the image side, and a negative lens on the image side. A lens component having a positive or negative refractive power as a whole, the fourth group includes a positive lens and a negative lens on the image side thereof, and each surface facing the positive lens and the negative lens is Both have a first adjacent surface with a concave surface facing the object side, and the fourth group is located closer to the image side than the first adjacent surface and further includes a positive lens and a negative lens from the object side. A small high-magnification wide-angle zoom lens that has a second adjacent surface with a concave surface facing the object side and satisfies the following conditions (4) and (5).
(4) 0 ≦ d ₄₁ /h≦0.05
(5) 0 ≦ d ₄₂ /h≦0.05
Here, d ₄₁ is the distance between the first adjacent surfaces of the fourth group, d ₄₂ is the distance between the second adjacent surfaces of the fourth group, and h is the maximum photographed image height.

In the zoom lens according to any one of claims 1 to 4, miniature high magnification wide-angle zoom lens, wherein the third lens component in the second group consists of one negative lens.

In the zoom lens according to any one of claims 1 to 5, and characterized in that the surface on the object side from the surface on the image side during the fourth group has an air lens of meniscus shape having a stronger refractive power A compact high-magnification wide-angle zoom lens.

In order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. When zooming from the wide end to the tele end, the first group moves to the object side, the second group moves so as to increase the distance from the first group, and the third group is the distance from the second group. The fourth group moves so that the distance from the third group is narrower at the tele end than at the wide end, and the second group has a convex surface on the object side in order from the object side. A negative meniscus lens having a negative refractive power composed of a first lens component, a negative lens and a positive lens, and a second lens component having a positive refractive power and a negative lens and a positive lens or one negative lens. It is composed of a third lens component, and each component is configured with an air gap in between, and the third group has an object side surface on the image side A positive lens having a refractive power stronger than that of the surface, a positive lens on the image side, and a lens component having a positive or negative refractive power as a whole. A negative lens on the image side, each of the opposing surfaces of the positive lens and the negative lens has a first adjacent surface with a concave surface facing the object side, and the fourth group includes the first lens Further, the surfaces adjacent to each other including the positive lens and the negative lens from the object side have a second adjacent surface with the concave surface facing the object side, and the following conditions (3) and (4) ) And (5) satisfying (5).
(3) 0.3 <| f ₂ | / f ₃ <0.45
(4) 0 ≦ d ₄₁ /h≦0.05
(5) 0 ≦ d ₄₂ /h≦0.05
Where f ₂ and f ₃ are the focal lengths of the second group and the third group, respectively, d ₄₁ is the distance between the first adjacent surfaces of the fourth group, d ₄₂ is the distance between the second adjacent surfaces of the fourth group, h is the maximum photographed image height.

In the zoom lens according to any one of claims 1 to 7, compact high magnification wide-angle zoom lens in which the first abutment surface is characterized in that it is a joint surface.

In order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. When zooming from the wide end to the tele end, the first group moves to the object side, the second group moves so as to increase the distance from the first group, and the third group is the distance from the second group. The fourth group moves so that the distance from the third group is narrower at the tele end than at the wide end, and the second group has a convex surface on the object side in order from the object side. A negative meniscus lens having a negative refractive power composed of a first lens component, a negative lens and a positive lens, and a second lens component having a positive refractive power and a negative lens and a positive lens or one negative lens. It is composed of a third lens component, and each component is configured with an air gap in between, and the third group has an object side surface on the image side A positive lens having a refractive power stronger than that of the surface, a positive lens on the image side, and a lens component having a positive or negative refractive power as a whole. A negative lens on the image side, each of the opposing surfaces of the positive lens and the negative lens has a first adjacent surface with a concave surface facing the object side, and the fourth group includes the first lens Further, the surfaces facing each other including the positive lens and the negative lens from the object side have a second adjacent surface with the concave surface facing the object side, and the second adjacent surface is joined. A compact high-magnification wide-angle zoom lens characterized by satisfying the following conditions (4) and (5) ′.
(4) 0 ≦ d ₄₁ /h≦0.05
_{(5) '0 = d 42} / h
Here, d ₄₁ is the distance between the first adjacent surfaces of the fourth group, d ₄₂ is the distance between the second adjacent surfaces of the fourth group, and h is the maximum photographed image height.

In the zoom lens according to any one of claims 1 to 9, small high magnification wide-angle zoom lens, wherein the zoom ratio is greater than 4.

In the zoom lens according to any one of claims 1 to 9, small high magnification wide-angle zoom lens, wherein the zoom ratio is greater than 4.6.

In the zoom lens according to any one of claims 1 to 11, small high magnification wide-angle zoom lens, wherein the telephoto ratio is 1.3 or less.

In the zoom lens according to any one of claims 1 to 11, small high magnification wide-angle zoom lens, wherein the telephoto ratio is 1.26 or less.

In the zoom lens according to any one of claims 1 to 13, small high magnification wide-angle zoom lens angle 2ω is equal to or more than 65 °.

In the zoom lens according to any one of claims 1 to 13, small high magnification wide-angle zoom lens angle 2ω is equal to or more than 75 °.