JPH09159917A - Rear focus type zoom lens - Google Patents
Rear focus type zoom lensInfo
- Publication number
- JPH09159917A JPH09159917A JP7323373A JP32337395A JPH09159917A JP H09159917 A JPH09159917 A JP H09159917A JP 7323373 A JP7323373 A JP 7323373A JP 32337395 A JP32337395 A JP 32337395A JP H09159917 A JPH09159917 A JP H09159917A
- Authority
- JP
- Japan
- Prior art keywords
- lens group
- lens
- refracting power
- rear focus
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 claims description 28
- 230000005499 meniscus Effects 0.000 claims description 6
- 230000004075 alteration Effects 0.000 abstract description 28
- 238000010586 diagram Methods 0.000 description 12
- 206010010071 Coma Diseases 0.000 description 4
- 201000009310 astigmatism Diseases 0.000 description 4
- 239000002131 composite material Substances 0.000 description 2
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 239000006059 cover glass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
Landscapes
- Lenses (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は特にスチルカメラや
ビデオカメラ等に好適な，変倍比が約１０に及びしかも
望遠端でもＦ３以内の口径比を持ちながり，レンズ系全
体の小型化を図ったリアフォーカス式ズームレンズに関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for a still camera, a video camera and the like, and has a variable power ratio of about 10 and has an aperture ratio of F3 or less even at the telephoto end, thereby reducing the size of the entire lens system. The present invention relates to a rear focus type zoom lens.
【０００２】[0002]
【従来の技術】従来よりスチルカメラや，ビデオカメラ
等のズームレンズにおいて用いられている比較的高変倍
比でしかも大口径比のズームレンズとして４群ズームレ
ンズが知られている。この４群ズームレンズは物体側よ
り順に焦点合わせに用いる第１レンズ群と，変倍に用い
る第２レンズ群と，変倍に伴う像面変動を一定位置に保
つように補正する第３レンズ群と，全系の焦点距離や収
差補正のバランスを取る為の第４レンズ群から成り立っ
ている。この様な４群ズームレンズでは変倍のために第
２レンズ群と第３レンズ群を移動させ，焦点合わせに第
１レンズ群を移動させている為，合計３つのレンズ群を
移動させなければならず，比較的レンズ鏡筒の機構が複
雑になる傾向があった。また，近距離物体に焦点合わせ
を行う際，第１レンズ群を物体側に繰り出して行うた
め，軸外光東を十分確保しようとすると前玉レンズ径が
増大する傾向があった。又，大径化した前玉を移動させ
るための大きな駆動力を要し，オートフォーカスに際し
ての合焦時間も長くなるという問題もあった。これらの
問題を防止するため，第１レンズ群以外のレンズ群を移
動させてフォーカスを行う，いわゆるリアフォーカス式
を採用したズームレンズが種々提案されている。一般に
リアフォーカス式ズームレンズは，前玉の繰り出しを伴
わないため，光量確保のために前玉径を大型化する必要
がなく，又，比較的小型軽量のレンズ群を移動させて焦
点合わせを行っているため，フォーカスを行う際の駆動
力が小さくて済み，迅速な焦点合わせが出来る。更に，
リアフォーカス式ズームレンズでは，第１レンズ群を移
動させて焦点合わせを行うズームレンズに比べて第１レ
ンズ群の有効径が小さくなり，レンズ系全体の小型化が
図りやすくなり，さらに近接撮影が容易になる等の優れ
た特長がある。2. Description of the Related Art A four-group zoom lens is known as a zoom lens having a relatively high zoom ratio and a large aperture ratio, which has been used in zoom lenses for still cameras and video cameras. The four-group zoom lens is a first lens group used for focusing in order from the object side, a second lens group used for zooming, and a third lens group for correcting image plane variation due to zooming so as to keep it at a fixed position. And a fourth lens group for balancing the focal length of the entire system and aberration correction. In such a four-group zoom lens, since the second lens group and the third lens group are moved for zooming and the first lens group is moved for focusing, a total of three lens groups must be moved. However, the lens barrel mechanism tends to be relatively complicated. Further, when focusing on an object at a short distance, the first lens group is extended toward the object side, so that there is a tendency for the front lens diameter to increase in order to sufficiently secure the off-axis optical east. In addition, there is a problem that a large driving force is required to move the front lens having a large diameter, and the focusing time for autofocusing becomes long. In order to prevent these problems, various zoom lenses adopting a so-called rear focus type have been proposed in which a lens group other than the first lens group is moved to perform focusing. In general, a rear-focus type zoom lens does not need to extend the front lens, so there is no need to increase the diameter of the front lens in order to secure the amount of light, and focusing is performed by moving a relatively small and lightweight lens group. Therefore, the driving force for focusing is small and quick focusing is possible. Furthermore,
In a rear focus type zoom lens, the effective diameter of the first lens group is smaller than that of a zoom lens in which focusing is performed by moving the first lens group, which makes it easier to reduce the size of the entire lens system, and further enables close-up photography. It has excellent features such as ease of use.
【０００３】[0003]
【発明が解決しようとする課題】しかしながらリアフォ
ーカス式ズームレンズでは，フォーカスの際における収
差変動が大きくなり，無限物体距離から近距離物体距離
に至るまで全般にわたりレンズ系全体の小型化を図りつ
つ，諸収差の良好に補正された高い光学性能を得ること
が大変困難であった。However, in the rear focus type zoom lens, the aberration variation during focusing becomes large, and the lens system as a whole is downsized from the infinite object distance to the short distance object distance. It was very difficult to obtain high optical performance with various aberrations corrected well.
【０００４】[0004]
【課題を解決するための手段】本発明は，この様な問題
点を解決するためになされたものであり，リアフォーカ
ス式ズームレンズを前提として，非球面を有するレンズ
を適切に配置する事により，リアフォーカス式を採用し
たにもかかわらず，変倍比１０で，かつ大口径比を持っ
たズームレンズでありながら，レンズ系全体の小型化を
図り，広角端から望遠端まで全物体距離で諸収差を良好
に補正された高い光学性能を有するリアフォーカス式ズ
ームレンズを得ることを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and by appropriately disposing a lens having an aspherical surface on the premise of a rear focus type zoom lens. Despite the use of the rear focus type, the zoom lens has a zoom ratio of 10 and a large aperture ratio, but the overall lens system is downsized, and the entire object distance from the wide-angle end to the telephoto end is achieved. An object of the present invention is to obtain a rear focus type zoom lens having high optical performance in which various aberrations are well corrected.
【０００５】上記目的を達成するため，本発明は図１の
光軸断面図に示す様に，物体側より順に，全体として正
の屈折力を持つ第１レンズ群Ａと，全体として負の屈折
力を有する第２レンズ群Ｂと，全体として正の屈折力を
有する第３レンズ群Ｃと，全体として正の屈折力を有す
る第４レンズ群Ｄと，全体として負の屈折力を有する第
５レンズ群Ｅよりなり，上記第１レンズ群Ａ，第３レン
ズ群Ｃ，第５レンズ群Ｅを固定させ，上記第２レンズ群
Ｂを光軸に沿って物体側から像面側へ移動させることに
より広角側から望遠側への変倍を行い，変倍に伴う像面
変動を上記第４レンズ群Ｄの光軸方向への移動により補
正すると共に，第４レンズ群Ｄを物体の移動によって変
動する像面を一定位置に保つように光軸に沿って移動さ
せて焦点調整を行うリアフォーカス式ズームレンズにお
いて，上記第３レンズ群Ｃの物体側の凸面と，上記第４
レンズ群Ｄの物体側の凸面に少なくとも一面の非球面形
状を有し，上記第５レンズ群Ｅの像面側の凸面に少なく
とも一面の非球面形状を有する事を特徴とするものであ
る。In order to achieve the above object, the present invention is, as shown in the optical axis sectional view of FIG. 1, in order from the object side, a first lens unit A having a positive refracting power as a whole and a negative refracting power as a whole. A second lens group B having a power, a third lens group C having a positive refractive power as a whole, a fourth lens group D having a positive refractive power as a whole, and a fifth lens group having a negative refractive power as a whole The first lens group A, the third lens group C, and the fifth lens group E are fixed, and the second lens group B is moved from the object side to the image plane side along the optical axis. The zooming is performed from the wide angle side to the telephoto side by means of, and the image plane fluctuation due to the zooming is corrected by the movement of the fourth lens group D in the optical axis direction, and the fourth lens group D is changed by the movement of the object. Adjust the focus by moving along the optical axis to keep the image surface at a fixed position. In the rear-focusing type zoom lens, the convex surface on the object side of the third lens group C, the fourth
The convex surface on the object side of the lens group D has at least one aspherical surface shape, and the convex surface on the image side of the fifth lens group E has at least one aspherical surface shape.
【０００６】望ましくは，本発明のリアフォーカス式ズ
ームレンズは，上記を前提として，前記第３レンズ群Ｃ
と前記第４レンズ群Ｄは，それぞれ両凸レンズと物体側
に強い凹面を向けた負のメニスカスレンズとの張り合わ
せレンズを有し，第３レンズ群Ｃの両凸レンズのアッべ
数をνｗ，第３レンズ群Ｃの物体側に強い凹面を向けた
負のメニスカスレンズのアッべ数をνｘ，第４レンズ群
Ｄの両凸レンズのアッべ数をνｙ，第４レンズ群Ｄの物
体側に強い凹面を向けた負のメニスカスレンズのアッべ
数をνｚとするとき，条件１及び条件２に規定する条件
を満足する。Preferably, the rear focus type zoom lens of the present invention is based on the above, and the third lens group C is used.
And the fourth lens group D has a cemented lens of a biconvex lens and a negative meniscus lens having a strong concave surface facing the object side, and the Abbe number of the biconvex lens of the third lens group C is νw, A negative meniscus lens having a strong concave surface facing the object side of the lens group C has an Abbe number of νx, a biconvex lens of the fourth lens group D has an Abbe number of νy, and a strong concave surface of the fourth lens group D has an object side. When the Abbe number of the negative meniscus lens aimed at is νz, the conditions defined in Condition 1 and Condition 2 are satisfied.
【０００７】（条件１）νｗ−νｘ＞２０(Condition 1) νw-νx> 20
【０００８】（条件２）νｙ−νｚ＞２０(Condition 2) νy-νz> 20
【０００９】更に望ましくは，本発明のリアフォーカス
式ズームレンズは，上記を前提として，広角端における
レンズ系全系の合成焦点距離をｆｗ，第２レンズ群Ｂの
合成焦点距離をｆ２，第４レンズ群Ｄの合成焦点距離を
ｆ４，第５レンズ群Ｅの合成焦点距離をｆ５とすると
き，条件３及び条件４に規定する条件を満足する。More preferably, in the rear focus type zoom lens of the present invention, the composite focal length of the entire lens system at the wide-angle end is fw, and the composite focal length of the second lens group B is f2, When the combined focal length of the lens group D is f4 and the combined focal length of the fifth lens group E is f5, the conditions defined in Condition 3 and Condition 4 are satisfied.
【００１０】 （条件３）０．７＜｜ｆ５／ｆ４｜＜１．７(Condition 3) 0.7 <| f5 / f4 | <1.7
【００１１】 （条件４）０．７＜｜ｆ２／ｆｗｌ＜１．１(Condition 4) 0.7 <| f2 / fwl <1.1
【００１２】[0012]
【作用】本発明は，図１の光軸断面図に示すように，物
体側より順に，全体として正の屈折力を持つ第１レンズ
群Ａと，全体として負の屈折力を有する第２レンズ群Ｂ
と，全体として正の屈折力を有する第３レンズ群Ｃと，
全体として正の屈折力を有する第４レンズ群Ｄと，全体
として負の屈折力を有する第５レンズ群Ｅよりなり，上
記第１レンズ群Ａ，第３レンズ群Ｃ，第５レンズ群Ｅは
固定されている。従って，変倍動作や合焦動作によって
レンズ系全体としての全長が変化することはなく，又，
可動レンズも第２レンズ群Ｂと第４レンズ群Ｄとに限定
されるので，駆動機構を簡素化することが可能となる。According to the present invention, as shown in the optical axis sectional view of FIG. 1, the first lens group A having a positive refracting power as a whole and the second lens having a negative refracting power as a whole in order from the object side. Group B
And a third lens group C having a positive refractive power as a whole,
The fourth lens unit D has a positive refracting power as a whole and the fifth lens unit E has a negative refracting power as a whole. The first lens unit A, the third lens unit C, and the fifth lens unit E are It is fixed. Therefore, the total length of the lens system as a whole does not change due to the zooming operation and the focusing operation.
Since the movable lenses are also limited to the second lens group B and the fourth lens group D, the driving mechanism can be simplified.
【００１３】変倍に際しては，固定レンズである第１レ
ンズ群Ａと第３レンズ群Ｃとの間に形成された空間にお
いて第２レンズ群Ｂを光軸に沿って物体側から像面側へ
移動させることにより広角側から望遠側への変倍がなさ
れ，又，この変倍に伴う像面変動の補正のために固定レ
ンズである第３レンズ群Ｃと第５レンズ群Ｅとの間に形
成された空間において第４レンズ群Ｄを物体側に凸状の
軌跡を有する様に移動させる。又，合焦動作に際して
は，固定レンズである第３レンズ群Ｃと第５レンズ群Ｅ
との間に形成された空間において第４レンズＤ群を物体
側に移動させることによって近距離側への焦点調整を行
う。この様に，固定レンズである第１レンズ群Ａと第３
レンズ群Ｃとの間に形成された固定空間，及び第３レン
ズ群Ｃと第５レンズ群Ｅとの間に形成された固定空間で
可動レンズである第２レンズ群Ｂ及び第４レンズ群Ｄを
移動させる様になされているので，可動レンズ群の限定
や固定空間の有効利用がなされ，駆動機構の簡素化やレ
ンズ系全体の小型化が達成される。At the time of zooming, the second lens group B is moved from the object side to the image plane side along the optical axis in the space formed between the first lens group A and the third lens group C, which are fixed lenses. By moving the zoom lens, zooming is performed from the wide-angle side to the telephoto side, and between the third lens group C and the fifth lens group E, which are fixed lenses, to correct the image plane variation due to this zooming. In the formed space, the fourth lens group D is moved so as to have a convex locus on the object side. In the focusing operation, the third lens group C and the fifth lens group E, which are fixed lenses, are used.
The fourth lens group D is moved to the object side in the space formed between and to adjust the focus to the near distance side. In this way, the first lens group A and the third
The second lens group B and the fourth lens group D which are movable lenses in a fixed space formed between the lens group C and a fixed space formed between the third lens group C and the fifth lens group E. Since the lens is moved, the movable lens group is limited and the fixed space is effectively used, which simplifies the drive mechanism and downsizes the entire lens system.
【００１４】第３レンズ群Ｃ，第４レンズ群Ｄの物体側
の凸面に配置された少なくとも１面の非球面形状及び第
５レンズ群Ｅの像面側の凸面に配置された少なくとも１
面の非球面形状は，変倍ならびに合焦動作の際における
収差変動を少なくし，諸収差を良好に補正するためのも
のである。At least one aspherical surface is disposed on the object-side convex surface of the third lens group C and the fourth lens group D, and at least one is disposed on the image-side convex surface of the fifth lens group E.
The aspherical shape of the surface is to reduce aberration fluctuations during zooming and focusing operations and to correct various aberrations well.
【００１５】これらの非球面中，第３レンズ群Ｃの物体
側の凸面に配置される非球面は主に広角側での球面収差
やコマ収差を良好に補正するのに有効である。又，第４
レンズ群Ｄの物体側の凸面に配置される非球面は，主に
球面収差や非点収差を良好に補正するのに有効である。
更に，第５レンズ群Ｅの像面側の凸面に配置される非球
面は，主に非点収差やコマ収差を良好に補正するのに有
効である。Of these aspherical surfaces, the aspherical surface arranged on the object-side convex surface of the third lens group C is effective mainly for favorably correcting spherical aberration and coma on the wide-angle side. Also, the fourth
The aspherical surface arranged on the object-side convex surface of the lens group D is effective mainly for favorably correcting spherical aberration and astigmatism.
Furthermore, the aspherical surface arranged on the image-side convex surface of the fifth lens group E is effective mainly for favorably correcting astigmatism and coma.
【００１６】さらに諸収差を良好に補正するために上述
の条件１乃至条件４に規定する条件を満足する事が好ま
しい。条件１に規定する条件は第３レンズ群Ｃの張り合
わせレンズのアッべ数を適切に設定するものである。条
件１に規定する条件が満足されないと，変倍および合焦
動作の際の色収差の変動を良好に補正するのが困難にな
る。Further, in order to satisfactorily correct various aberrations, it is preferable that the above conditions 1 to 4 are satisfied. The condition defined in the condition 1 is to appropriately set the Abbe number of the cemented lens of the third lens group C. If the condition defined in Condition 1 is not satisfied, it becomes difficult to satisfactorily correct fluctuations in chromatic aberration during zooming and focusing operations.
【００１７】条件２に規定する条件は第４レンズ群の張
り合わせレンズのアッべ数を適切に設定するものであ
る。条件２に規定する条件が満足されないと，変倍およ
び合焦動作の際の色収差の変動を良好に補正するのが難
しくなってくる。The condition defined in the condition 2 is to appropriately set the Abbe number of the cemented lens of the fourth lens unit. If the condition defined in Condition 2 is not satisfied, it becomes difficult to satisfactorily correct fluctuations in chromatic aberration during zooming and focusing operations.
【００１８】条件３に規定する条件は第４レンズ群Ｄ
と，第５レンズ群Ｅの焦点距離に関するものであり，変
倍および合焦動作の際における第４レンズ群Ｄの移動量
を抑制してレンズ系全体の小型化を図る一方で，良好な
光学性能を維持するためのものである。条件３の上限値
を越えると，変倍および合焦動作の際における第４レン
ズ群Ｄの移動量が大きくなり，収差変動が大きくなると
共にレンズ系全体の小型化が望めなくなる。条件３の下
限値を越えると変倍および合焦動作の際における第４レ
ンズ群Ｄの移動量は小さくなるが，非点収差およびコマ
収差の補正が困難となる。The condition defined in condition 3 is the fourth lens group D.
And the focal length of the fifth lens group E, which suppresses the movement amount of the fourth lens group D during zooming and focusing operations to reduce the size of the entire lens system, while achieving good optical It is for maintaining the performance. If the upper limit of condition 3 is exceeded, the amount of movement of the fourth lens unit D during zooming and focusing becomes large, aberration fluctuations increase, and miniaturization of the entire lens system cannot be expected. When the value goes below the lower limit of the condition 3, the amount of movement of the fourth lens unit D at the time of zooming and focusing becomes small, but it becomes difficult to correct astigmatism and coma.
【００１９】条件４に規定する条件は第２レンズ群Ｂの
焦点距離に関するものであり，変倍の際の収差変動を抑
えつつ，レンズ系全体の小型化を図るためのものであ
る。条件４の上限値を越えると，一定の変倍比を確保す
る為に第２レンズ群Ｂの移動量が大きくなり，レンズ系
全体の小型化が望めなくなる。条件４の下限値を越える
と，負のべッツバール和が増大し，像面湾曲が大きくな
る。またコマ収差の補正も困難となる。The condition defined in Condition 4 relates to the focal length of the second lens unit B, and is intended to reduce the size of the entire lens system while suppressing the aberration variation during zooming. If the upper limit of condition 4 is exceeded, the amount of movement of the second lens unit B becomes large in order to secure a constant zoom ratio, and it becomes impossible to expect miniaturization of the entire lens system. When the value goes below the lower limit of Condition 4, the negative Betzvar sum increases and the field curvature increases. It also becomes difficult to correct coma.
【００２０】[0020]
【実施例】次に，具体的な数値実施例を表１及び表２に
示すとともに，各々の実施例の光軸断面を図１乃至図３
及び図７乃至図９に示し，又，各々の実施例の収差線図
を図４乃至図６及び図１０乃至図１２に示す。尚，図１
及び図７は各々の実施例の広角端での光軸断面を，図２
及び図８は各々実施例の中間焦点距離での光軸断面を，
図３及び図９は各々の実施例の望遠端での光軸断面図を
示す，図４及び図１０は各々の実施例の広角端での収差
線図を，図５及び図１１は各々の実施例の中間焦点距離
での収差線図を，図６及び図１２は各々の実施例の望遠
端での収差線図を示している。又，各々の光軸断面図に
おいて，Ａ乃至Ｅは各々第１レンズ群から第５レンズ群
を示すとともに，ＦはＣＣＤにおけるカバーガラスや赤
外カットフィルター等のガラス材を表す。EXAMPLES Next, specific numerical examples are shown in Tables 1 and 2, and the optical axis cross sections of the respective examples are shown in FIGS.
7 to 9 and the aberration diagrams of the respective examples are shown in FIGS. 4 to 6 and 10 to 12. FIG.
7 and 8 are sectional views of the optical axis at the wide-angle end of each embodiment.
And FIG. 8 are cross-sectional views of the optical axis at the intermediate focal length of the embodiment,
3 and 9 are sectional views of the optical axis at the telephoto end of each embodiment, FIGS. 4 and 10 are aberration diagrams at the wide-angle end of each embodiment, and FIGS. FIGS. 6 and 12 show aberration diagrams at the intermediate focal length of the examples, and FIGS. 6 and 12 show aberration diagrams at the telephoto end of the examples. Further, in each optical axis sectional view, A to E indicate the first to fifth lens groups, respectively, and F indicates a glass material such as a cover glass or an infrared cut filter in the CCD.
【００２１】[0021]
【表１】 [Table 1]
【００２２】[0022]
【表２】 [Table 2]
【００２３】各々の実施例において，ｒｉは物体側から
ｉ番目の面の曲率半径を，ｄｉは物体からｉ番目のレン
ズ肉厚或いは空気間隔を，ｎｉは物体からｉ番目のレン
ズのｄ線に対する屈折率を，νｉは物体からｉ番目のレ
ンズのｄ線に対するアッベ数を各々示している。又，表
１に示す実施例ではｒ１２面，ｒ１４面，ｒ１７面，ｒ
２１面が非球面に形成され，表２に示す実施例ではｒ１
２面，ｒ１５面，ｒ１７面，ｒ１９面が非球面に形成さ
れ，その非球面形状は数１によって規定されている。In each embodiment, ri is the radius of curvature of the i-th surface from the object side, di is the i-th lens thickness or air gap from the object, and ni is the d-line of the i-th lens from the object. Refractive index, νi, is the Abbe number for the d-line of the i-th lens from the object. Further, in the examples shown in Table 1, r12 surface, r14 surface, r17 surface, r
21 surfaces are formed as aspherical surfaces, and in the embodiment shown in Table 2, r1
The two surfaces, the r15 surface, the r17 surface, and the r19 surface are formed into an aspherical surface, and the aspherical surface shape is defined by Equation 1.
【００２４】[0024]
【数１】 [Equation 1]
【００２５】尚，数１において，Ｚは光軸から高さがｙ
の非球面上の点の非球面頂点の接平面からの距離を，ｙ
は光軸からの高さを，Ｃは非球面頂点の曲率（＝１／
ｒ）を，εは円錐定数を，Ｄ，Ｅ，Ｆ及びＧは非球面係
数を表し，ε，Ｄ，Ｅ，Ｆ及びＧの具体的な数値は各々
表１及び表２に示されている。又，各々の収差線図にお
ける非点収差は，図面の煩雑化を避けるためにサジタル
方向ＤＳとメリジオナル方向とを各々区分して示してい
る。In equation 1, Z has a height y from the optical axis.
The distance from the tangent plane of the aspherical vertex of the aspherical surface of
Is the height from the optical axis, C is the curvature of the aspherical vertex (= 1 /
r), ε is a conic constant, D, E, F and G are aspherical coefficients, and concrete values of ε, D, E, F and G are shown in Table 1 and Table 2, respectively. . In addition, astigmatism in each aberration diagram is shown by dividing the sagittal direction DS and the meridional direction separately in order to avoid complication of the drawing.
【００２６】[0026]
【発明の効果】以上説明した実施例や収差線図に見られ
る様に，本発明は，リアフォーカス式を採用しつつ，約
１０倍の広域な変倍比と望遠端でもＦ３以内の口径を有
する高変倍比，大口径のズームレンズでありながら，レ
ンズ系全体の小型化を図りつつ，広角端から望遠端まで
全物体距離にわたって諸収差が良好に補正された高い光
学性能を有するリアフォーカス式ズームレンズを得るこ
とが出来た。As can be seen from the above-described embodiments and aberration diagrams, the present invention adopts the rear focus type and has a wide zoom ratio of about 10 times and an aperture within F3 even at the telephoto end. Despite being a zoom lens with a high zoom ratio and a large aperture, the rear focus has high optical performance with various aberrations well corrected over the entire object distance from the wide-angle end to the telephoto end while aiming to downsize the entire lens system. I was able to get a zoom lens.
【図１】本発明の第１実施例に係るズームレンズの広角
端での光軸断面図。FIG. 1 is a sectional view of an optical axis at a wide-angle end of a zoom lens according to Example 1 of the present invention.
【図２】本発明の第１実施例に係るズームレンズの中間
焦点距離での光軸断面図。FIG. 2 is a sectional view of the optical axis of the zoom lens according to Example 1 of the present invention at an intermediate focal length.
【図３】本発明の第１実施例に係るズームレンズの望遠
端での光軸断面図。FIG. 3 is a sectional view of the optical axis at the telephoto end of the zoom lens according to Example 1 of the present invention.
【図４】本発明の第１実施例に係るズームレンズの広角
端での収差線図。FIG. 4 is an aberration diagram at a wide-angle end of the zoom lens according to Example 1 of the present invention.
【図５】本発明の第１実施例に係るズームレンズの中間
焦点距離での収差線図。FIG. 5 is an aberration diagram at an intermediate focal length of the zoom lens according to Example 1 of the present invention.
【図６】本発明の第１実施例に係るズームレンズの望遠
端での収差線図。FIG. 6 is an aberration diagram at the telephoto end of the zoom lens according to Example 1 of the present invention.
【図７】本発明の第２実施例に係るズームレンズの広角
端での光軸断面図。FIG. 7 is a sectional view of an optical axis at a wide-angle end of a zoom lens according to a second example of the present invention.
【図８】本発明の第２実施例に係るズームレンズの中間
焦点距離での光軸断面図。FIG. 8 is a sectional view of an optical axis of a zoom lens according to Example 2 of the present invention at an intermediate focal length.
【図９】本発明の第２実施例に係るズームレンズの望遠
端での光軸断面図。FIG. 9 is a sectional view of an optical axis at a telephoto end of a zoom lens according to a second example of the present invention.
【図１０】本発明の第２実施例に係るズームレンズの広
角端での収差線図。FIG. 10 is an aberration diagram at a wide-angle end of the zoom lens according to Example 2 of the present invention.
【図１１】本発明の第２実施例に係るズームレンズの中
間焦点距離での収差線図。FIG. 11 is an aberration diagram at an intermediate focal length of the zoom lens according to Example 2 of the present invention.
【図１２】本発明の第２実施例に係るズームレンズの望
遠端での収差線図。FIG. 12 is an aberration diagram at a telephoto end of a zoom lens according to Example 2 of the present invention.
Ａ 第１レンズ群 Ｂ 第２レンズ群 Ｃ 第３レンズ群 Ｄ 第４レンズ群 Ｅ 第５レンズ群 A first lens group B second lens group C third lens group D fourth lens group E fifth lens group
Claims (3)
を持つ第１レンズ群と，全体として負の屈折力を有する
第２レンズ群と，全体として正の屈折力を有する第３レ
ンズ群と，全体として正の屈折力を有する第４レンズ群
と，全体として負の屈折力を有する第５レンズ群よりな
り，上記第１レンズ群，第３レンズ群，第５レンズ群を
固定させ，上記第２レンズ群を光軸に沿って物体側から
像面側へ移動させることにより広角側から望遠側への変
倍を行い，変倍に伴う像面変動を上記第４レンズ群の光
軸方向への移動により補正すると共に，第４レンズ群を
物体の移動によって変動する像面を一定位置に保つよう
に光軸に沿って移動させて焦点調整を行う光学系におい
て，上記第３レンズ群の物体側の凸面と，上記第４レン
ズ群の物体側の凸面に少なくとも一面の非球面形状を有
し，上記第５レンズ群の像面側の凸面に少なくとも一面
の非球面形状を有する事を特徴とした，リアフォーカス
式ズームレンズ1. A first lens group having a positive refracting power as a whole, a second lens group having a negative refracting power as a whole, and a third lens group having a positive refracting power as a whole in order from the object side. And a fourth lens group having a positive refracting power as a whole and a fifth lens group having a negative refracting power as a whole, and fixing the first lens group, the third lens group, and the fifth lens group, The second lens group is moved along the optical axis from the object side to the image plane side to change the magnification from the wide-angle side to the telephoto side, and the image plane variation due to the magnification change is caused by the optical axis of the fourth lens group. In the optical system, the fourth lens group is moved along the optical axis so as to keep the image plane fluctuated by the movement of the object at a constant position while performing the correction by the movement in the direction. Object-side convex surface of and the object-side convex surface of the fourth lens group A rear focus type zoom lens, characterized in that at least one aspherical surface is formed on the image side, and at least one aspherical surface is formed on the image-side convex surface of the fifth lens group.
レンズにおいて，前記第３レンズ群と前記第４レンズ群
は，それぞれ両凸レンズと物体側に強い凹面を向けた負
のメニスカスレンズとの張り合わせレンズを有し，第３
レンズ群の両凸レンズのアッべ数をνｗ，第３レンズ群
の物体側に強い凹面を向けた負のメニスカスレンズのア
ッべ数をνｘ，第４レンズ群の両凸レンズのアッべ数を
νｙ，第４レンズ群の物体側に強い凹面を向けた負のメ
ニスカスレンズのアッべ数をνｚとするとき， （条件１）νｗ−νｘ＞２０ （条件２）νｙ−νｚ＞２０ なる条件式を満足する事を特徴とする請求項１記載のリ
アフォーカス式ズームレンズ。2. The rear focus type zoom lens according to claim 1, wherein the third lens group and the fourth lens group are cemented lenses each comprising a biconvex lens and a negative meniscus lens having a strong concave surface facing the object side. Have a third
The Abbe number of the biconvex lens of the lens group is νw, the Abbe number of the negative meniscus lens having a strong concave surface facing the object side of the third lens group is νx, the Abbe number of the biconvex lens of the fourth lens group is νy, When the Abbe number of the negative meniscus lens with the strong concave surface facing the object side of the fourth lens group is νz, (condition 1) νw−νx> 20 (condition 2) νy−νz> 20 is satisfied. The rear focus type zoom lens according to claim 1, wherein:
カス式ズームレンズにおいて，広角端におけるレンズ系
全系の合成焦点距離をｆｗ，第２レンズ群の合成焦点距
離をｆ２，第４レンズ群の合成焦点距離をｆ４，第５レ
ンズ群の合成焦点距離をｆ５とするとき， （条件３）０．７＜｜ｆ５／ｆ４｜＜１．７ （条件４）０．７＜｜ｆ２／ｆｗｌ＜１．１ なる条件式を満足することを特徴とするリアフォーカス
式ズームレンズ。3. The rear focus type zoom lens according to claim 1, wherein the combined focal length of the entire lens system at the wide-angle end is fw, the combined focal length of the second lens unit is f2, and the fourth lens unit. Where f5 is the combined focal length of F4 and f5 is the combined focal length of the fifth lens group, (condition 3) 0.7 <| f5 / f4 | <1.7 (condition 4) 0.7 <| f2 / fwl A rear focus zoom lens which satisfies the conditional expression <1.1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32337395A JP3593400B2 (en) | 1995-12-12 | 1995-12-12 | Rear focus zoom lens |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32337395A JP3593400B2 (en) | 1995-12-12 | 1995-12-12 | Rear focus zoom lens |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09159917A true JPH09159917A (en) | 1997-06-20 |
| JP3593400B2 JP3593400B2 (en) | 2004-11-24 |
Family
ID=18154041
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32337395A Expired - Fee Related JP3593400B2 (en) | 1995-12-12 | 1995-12-12 | Rear focus zoom lens |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3593400B2 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09269452A (en) * | 1996-03-29 | 1997-10-14 | Canon Inc | Rear focus system zoom lens |
| US7064903B2 (en) | 2004-04-01 | 2006-06-20 | Canon Kabushiki Kaisha | Lens device and shooting system |
| JP2008102398A (en) * | 2006-10-20 | 2008-05-01 | Olympus Imaging Corp | Variable power optical system and imaging apparatus using the same |
| EP2048533A1 (en) * | 2007-10-01 | 2009-04-15 | Nikon Corporation | Zoom lens, optical apparatus equipped with the zoom lens and method for forming an image of an object and varying a focal length |
| JP2014102358A (en) * | 2012-11-19 | 2014-06-05 | Ricoh Co Ltd | Imaging lens, imaging device, and information device |
| CN104965297A (en) * | 2015-06-25 | 2015-10-07 | 福建省光学技术研究所 | Rear group adjusting video shooting high-definition zoom lens and rear group adjusting method for lens |
| JP2020101736A (en) * | 2018-12-25 | 2020-07-02 | 株式会社シグマ | Zoom imaging optical system |
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| JPH08327904A (en) * | 1995-05-30 | 1996-12-13 | Canon Inc | Small-sized zoom lens |
| JPH0968653A (en) * | 1995-08-30 | 1997-03-11 | Olympus Optical Co Ltd | Zoom lens |
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|---|---|---|---|---|
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09269452A (en) * | 1996-03-29 | 1997-10-14 | Canon Inc | Rear focus system zoom lens |
| US7064903B2 (en) | 2004-04-01 | 2006-06-20 | Canon Kabushiki Kaisha | Lens device and shooting system |
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| EP2048533A1 (en) * | 2007-10-01 | 2009-04-15 | Nikon Corporation | Zoom lens, optical apparatus equipped with the zoom lens and method for forming an image of an object and varying a focal length |
| US7903344B2 (en) | 2007-10-01 | 2011-03-08 | Nikon Corporation | Zoom lens, optical apparatus equipped with the zoom lens and method for forming an image of an object and varying a focal length |
| CN104391369A (en) * | 2007-10-01 | 2015-03-04 | 株式会社尼康 | Zoom lens, optical apparatus and method for forming an image of an object and changing a focal length |
| JP2014102358A (en) * | 2012-11-19 | 2014-06-05 | Ricoh Co Ltd | Imaging lens, imaging device, and information device |
| CN104965297A (en) * | 2015-06-25 | 2015-10-07 | 福建省光学技术研究所 | Rear group adjusting video shooting high-definition zoom lens and rear group adjusting method for lens |
| CN104965297B (en) * | 2015-06-25 | 2017-05-24 | 福建省光学技术研究所 | Rear group adjusting video shooting high-definition zoom lens and rear group adjusting method for lens |
| JP2020101736A (en) * | 2018-12-25 | 2020-07-02 | 株式会社シグマ | Zoom imaging optical system |
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