JPH07333504A - Zoom lens - Google Patents

Zoom lens

Info

Publication number
JPH07333504A
JPH07333504A JP6150317A JP15031794A JPH07333504A JP H07333504 A JPH07333504 A JP H07333504A JP 6150317 A JP6150317 A JP 6150317A JP 15031794 A JP15031794 A JP 15031794A JP H07333504 A JPH07333504 A JP H07333504A
Authority
JP
Japan
Prior art keywords
group
lens
refractive power
wide
zoom lens
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
Application number
JP6150317A
Other languages
Japanese (ja)
Other versions
JP3175484B2 (en
Inventor
Takashi Kato
隆志 加藤
Teruhiro Nishio
彰宏 西尾
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Priority to JP15031794A priority Critical patent/JP3175484B2/en
Publication of JPH07333504A publication Critical patent/JPH07333504A/en
Priority to US08/735,571 priority patent/US5691851A/en
Application granted granted Critical
Publication of JP3175484B2 publication Critical patent/JP3175484B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B15/00—Optical objectives with means for varying the magnification
    • G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
    • G02B15/143—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only
    • G02B15/1435—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only the first group being negative
    • G02B15/143503—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having three groups only the first group being negative arranged -+-

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Lenses (AREA)

Abstract

PURPOSE:To provide a zoom lens having a wide viewing angle and high variable power ratio while miniaturizing the whole lens system by composing it with three lens groups as a whole and properly setting the lens constitution of each lens group. CONSTITUTION:This zoom lens comprises three lens groups of a first group of negative refractive power, a second group of positive refractive power and a third group of negative refractive power in order from the object side, the second group comprises four lens groups of a 2a group, a 2b group, a 2c group and a 2d group, power variation is performed by changing the air gaps of the four lens groups in the second group and by representing composite focal distances at the wide-angle end and the telescopic end in the second group by f2w, f2T, respectively, the condition: f2w<f2T is satisfied.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は３５ｍｍフィルム用の写
真用カメラやビデオカメラそしてＳＶカメラ等に好適な
ズームレンズに関し、特に複数のレンズ群、例えば全体
として３つのグループのレンズ群より構成して、これら
３つのグループの各レンズ群のレンズ構成を適切に設定
することによりレンズ系全体の小型化を図りつつ高い光
学性能が容易に得られるようにした広画角で高変倍比の
ズームレンズに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens suitable for a 35 mm film photographic camera, a video camera, an SV camera and the like, and in particular, it comprises a plurality of lens groups, for example, a total of three lens groups. , A zoom lens having a wide angle of view and a high zoom ratio, which is capable of easily obtaining high optical performance while downsizing the entire lens system by appropriately setting the lens configuration of each lens group of these three groups. It is about.

【０００２】[0002]

【従来の技術】従来よりズームタイプとして負の屈折力
のレンズ群が先行する所謂ネガティブリード型のズーム
レンズは広画角化が比較的容易であるため、撮影画角７
０°以上を有するズームレンズには多く用いられてい
る。2. Description of the Related Art Conventionally, a so-called negative lead type zoom lens in which a zoom type lens group having a negative refracting power precedes is relatively easy to have a wide angle of view.
It is often used for zoom lenses having an angle of 0 ° or more.

【０００３】例えば、特開昭５９−１６２４８号公報で
は負の屈折力の第１群と正の屈折力の第２群の２つのレ
ンズ群を有し、両レンズ群の間隔を変えて変倍を行った
所謂ショートズームレンズを提案している。For example, Japanese Laid-Open Patent Publication No. 59-16248 has two lens groups, a first lens group having a negative refractive power and a second lens group having a positive refractive power, and the zooming is performed by changing the distance between the two lens groups. The so-called short zoom lens is proposed.

【０００４】又、特開平２−７２３１６号公報や特開平
３−２３３４２２号公報では物体側より順に負の屈折力
の第１群と正の屈折力の第２群、そして負の屈折力の第
３群の３つのレンズ群を有し、各レンズ群を移動させて
変倍を行った広画角の３群ズームレンズを提案してい
る。Further, in JP-A-2-73216 and JP-A-3-233422, a first group having a negative refractive power, a second group having a positive refractive power, and a second group having a negative refractive power are sequentially arranged from the object side. It proposes a three-group zoom lens having a wide angle of view, which has three lens groups of three groups, and each lens group is moved for zooming.

【０００５】又、特開平２−７２３１６号公報では物体
側より順に負の屈折力の第１群と正の屈折力の第２群、
正の屈折力の第３群、そして負の屈折力の第４群より成
り、各レンズ群を移動させて変倍を行った４群ズームレ
ンズを提案している。Further, in Japanese Patent Application Laid-Open No. 2-73216, a first group having a negative refractive power and a second group having a positive refractive power are arranged in order from the object side.
It proposes a four-group zoom lens composed of a third group having a positive refractive power and a fourth group having a negative refractive power, in which each lens group is moved to perform zooming.

【０００６】一方、ズームタイプとして物体側より順に
正の屈折力の第１群と負の屈折力の第２群の２つのレン
ズ群を有し、双方を移動させて変倍を行う所謂２群ズー
ムレンズはレンズ系全体の小型化が容易なためにレンズ
シャッターカメラ等の小型カメラに多く用いられてい
る。２群ズームレンズは変倍作用を一つのレンズ群（第
２群）のみで行っているために、その変倍比が１．６〜
２倍程度のものが多い。２群ズームレンズにおいて無理
に変倍比を拡大しようとするとレンズ系の大型化を招く
とともに、高い光学性能を保つことが困難になってく
る。On the other hand, as a zoom type, it has two lens groups, a first lens group having a positive refractive power and a second lens group having a negative refractive power in order from the object side. Zoom lenses are often used in small cameras such as lens shutter cameras because it is easy to downsize the entire lens system. The zoom ratio of the two-group zoom lens is 1.6 to 1.6 because only one lens group (second group) performs zooming.
Many are about twice as many. If the zoom ratio of the two-group zoom lens is forcibly increased, the size of the lens system becomes large and it becomes difficult to maintain high optical performance.

【０００７】又、２群ズームレンズにおいて第１群を２
つの正の屈折力のレンズ群に分割し、全体として正、
正、負の屈折力の３つのレンズ群より成る高変倍化を狙
った３群ズームレンズが、例えば特開平３−７３９０７
号公報、特開平３−２８２４０９号公報、特開平４−３
７８１０号公報、特開平４−７６５１１号公報等で提案
されている。In the second group zoom lens, the first group is
Divided into two positive refractive power lens groups, positive overall,
A three-group zoom lens composed of three lens groups having positive and negative refracting power and aiming for high zooming is disclosed in, for example, Japanese Patent Laid-Open No. 3-73907.
Japanese Patent Laid-Open No. 3-282409, Japanese Patent Laid-Open No. 4-3
It is proposed in Japanese Patent No. 7810, Japanese Patent Laid-Open No. 4-76511, and the like.

【０００８】これらの３群ズームレンズで例えば半画角
３５°以上の広角のズームレンズ系を達成しようとする
と変倍時の入射瞳位置の変化が大きくなり、高変倍化を
図る際の収差変動を抑えることが困難になってくる。When an attempt is made to achieve a wide-angle zoom lens system having a half field angle of 35 ° or more with these three-group zoom lenses, the position of the entrance pupil at the time of zooming becomes large, and aberrations at the time of achieving high zooming become large. It becomes difficult to control fluctuations.

【０００９】[0009]

【発明が解決しようとする課題】一般にネガティブリー
ド型のズームレンズは広画角化が比較的容易である。し
かしながら、撮影画角７０°以上の広画角化を図り、全
画面にわたり良好なる光学性能を得るには各レンズ群の
屈折力配置やレンズ構成を適切に設定する必要がある。
各レンズ群の屈折力配置やレンズ構成が不適切であると
レンズ枚数を増加させても変倍に伴う収差変動が大きく
なり、全変倍範囲にわたり高い光学性能を得るのが難し
くなってくる。Generally, a negative lead type zoom lens is relatively easy to have a wide angle of view. However, in order to achieve a wide field angle of 70 ° or more and obtain good optical performance over the entire screen, it is necessary to properly set the refractive power arrangement and lens configuration of each lens group.
If the refractive power arrangement or lens configuration of each lens group is improper, even if the number of lenses is increased, the aberration variation due to zooming becomes large, and it becomes difficult to obtain high optical performance over the entire zoom range.

【００１０】例えば特開平３−２３３４２２号公報にお
いては、負、正、負の屈折力の３つのレンズ群で構成し
た広画角のズームレンズを提案している。しかしなが
ら、同公報で提案しているズームレンズは光学全長が広
角端において約６６ｍｍ程度であり、レンズ全長が短い
とは言い難く、また更なる広角化を行った場合、全変倍
域にわたり良好な収差補正を行うことは難しい。For example, Japanese Laid-Open Patent Publication No. 3-233422 proposes a wide-angle zoom lens composed of three lens groups having negative, positive, and negative refracting powers. However, the zoom lens proposed in this publication has an optical total length of about 66 mm at the wide-angle end, and it is hard to say that the lens total length is short, and when further widening the angle is achieved, it is favorable over the entire zoom range. Aberration correction is difficult.

【００１１】本発明は複数のレンズ群を有するズームレ
ンズにおいて、例えば全体として３つのグループのレン
ズ群に分けたズームレンズにおいて各レンズ群のレンズ
構成を適切に設定することにより、広画角化及び高変倍
時に問題となってくる諸収差を良好に補正しつつレンズ
系全体の小型化を図った全変倍範囲にわたり高い光学性
能を有したズームレンズの提供を目的とする。According to the present invention, in a zoom lens having a plurality of lens groups, for example, in a zoom lens divided into three groups as a whole, by appropriately setting the lens configuration of each lens group, a wide angle of view and It is an object of the present invention to provide a zoom lens having high optical performance over the entire zooming range, in which various aberrations which become a problem at the time of high zooming are favorably corrected and the entire lens system is downsized.

【００１２】[0012]

【課題を解決するための手段】本発明のズームレンズ
は、物体側より順に負の屈折力の第１群、正の屈折力の
第２群、そして負の屈折力の第３群の３つのレンズ群を
有し、該第２群は第２ａ群、第２ｂ群、第２ｃ群、そし
て第２ｄ群の４つのレンズ群を有し、該第２群中の４つ
のレンズ群の空気間隔を変えて変倍を行い、該第２群の
広角端と望遠端の合成焦点距離を各々ｆ２ｗ，ｆ２Ｔと
したとき、 ｆ２ｗ＜ｆ２Ｔ ・・・・・・（１） なる条件を満足することを特徴としている。A zoom lens according to the present invention comprises three lens units, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power in order from the object side. The second lens group has four lens groups, that is, the second lens group, the second lens group, the second lens group, the second lens group, and the second lens group, and the air distances of the four lens groups in the second lens group are equal to each other. When the magnification is changed and the combined focal lengths of the wide-angle end and the telephoto end of the second lens unit are f2w and f2T, f2w <f2T (1) is satisfied. I am trying.

【００１３】[0013]

【実施例】図１〜図４は本発明のズームレンズの実施例
１〜４の近軸屈折力配置を示す模式図である。図５〜図
８は本発明のズームレンズの後述する数値実施例１〜４
の広角端のレンズ断面図である。図１〜図４において
（Ａ）は広角端、（Ｂ）は望遠端を示している。図９〜
図１１は本発明の数値実施例１の広角端、中間、望遠端
の収差図、図１２〜図１４は本発明の数値実施例２の広
角端、中間、望遠端の収差図、図１５〜図１７は本発明
の数値実施例３の広角端、中間、望遠端の収差図、図１
８〜図２０は本発明の数値実施例４の広角端、中間、望
遠端の収差図である。1 to 4 are schematic views showing the paraxial refractive power arrangements of Examples 1 to 4 of the zoom lens of the present invention. 5 to 8 are numerical examples 1 to 4 to be described later of the zoom lens of the present invention.
2 is a lens cross-sectional view at the wide-angle end of FIG. 1 to 4, (A) shows the wide-angle end and (B) shows the telephoto end. 9-
11 is an aberration diagram at the wide-angle end, the middle, and the telephoto end of Numerical Example 1 of the present invention, and FIGS. 12 to 14 are aberration diagrams at the wide-angle end, the middle, and the telephoto end of Numerical Example 2 of the present invention, and FIGS. FIG. 17 is an aberration diagram at the wide-angle end, the middle, and the telephoto end according to Numerical Embodiment 3 of the present invention.
8 to 20 are aberration diagrams at the wide-angle end, the middle, and the telephoto end of Numerical Embodiment 4 of the present invention.

【００１４】図中、Ｌ１は負の屈折力の第１群、Ｌ２は
正の屈折力の第２群、Ｌ３は負の屈折力の第３群、ＳＰ
は開口絞り、ＩＰは像面である。In the figure, L1 is a first group having a negative refractive power, L2 is a second group having a positive refractive power, L3 is a third group having a negative refractive power, and SP.
Is an aperture stop, and IP is an image plane.

【００１５】本発明のズームレンズは第２群を複数のレ
ンズ群より構成している。図１〜図４の各実施例では便
宜上全体として負の屈折力の第１群Ｌ１、正の屈折力の
第２群Ｌ２、そして負の屈折力の第３群の３つのグルー
プに分けている。そして基本的に第１群Ｌ１と第２群Ｌ
２のレンズ群間隔と第２群Ｌ２と第３群のレンズ群間隔
が変化するように、各レンズ群を矢印の如く移動させて
広角端から望遠端への変倍を行っている。In the zoom lens according to the present invention, the second group is composed of a plurality of lens groups. In each of the embodiments shown in FIGS. 1 to 4, for the sake of convenience, they are divided into three groups, that is, a first group L1 having a negative refractive power, a second group L2 having a positive refractive power, and a third group having a negative refractive power. . And basically, the first group L1 and the second group L
Each lens group is moved as shown by an arrow so that the distance between the second lens group and the distance between the second lens group L2 and the third lens group is changed to perform zooming from the wide-angle end to the telephoto end.

【００１６】第２群Ｌ２は、第２ａ群Ｌ２ａ、第２ｂ群
Ｌ２ｂ、第２ｃ群Ｌ２ｃ、そして第２ｄ群Ｌ２ｄの４つ
のレンズ群より構成しており、広角端から望遠端への変
倍に際して、これらの各レンズ群を各々物体側へ移動さ
せている。本実施例では第２ａ群Ｌ２ａと第２ｂ群Ｌ２
ｂとから合成屈折力が正の第２Ｆ群を構成し、第２ｃ群
Ｌ２ｃと第２ｄ群Ｌ２ｄとから合成屈折力が正の第２Ｒ
群を構成している。The second lens unit L2 is composed of four lens units, that is, a second lens unit L2a, a second lens unit L2b, a second lens unit L2c, and a second lens unit L2d, and at the time of zooming from the wide-angle end to the telephoto end. , Each of these lens groups is moved to the object side. In the present embodiment, the second-a group L2a and the second-b group L2
b and a second F group having a positive combined refractive power, and a second R group having a positive combined refractive power from the second c group L2c and the second d group L2d.
Make up a group.

【００１７】また本発明では、このような複数のレンズ
群より構成したとき、前述の条件式（１）を満足するよ
うに第２群の広角端と望遠端の横倍率を設定することに
より広画角及び高変倍化を図る際の収差変動を良好に補
正し、全変倍範囲にわたり高い光学性能を得ている。条
件式（１）を外れると変倍を効率的に行うのが難しくな
ってくる。Further, according to the present invention, when such a plurality of lens groups is used, the lateral magnifications at the wide-angle end and the telephoto end of the second group are set so as to satisfy the conditional expression (1). Aberration variation at the time of increasing the angle of view and high zooming is corrected well, and high optical performance is obtained over the entire zooming range. If the conditional expression (1) is not satisfied, it becomes difficult to perform zooming efficiently.

【００１８】次に本発明のズームレンズのレンズ構成の
特徴について説明する。Next, the features of the lens structure of the zoom lens of the present invention will be described.

【００１９】本発明のズームレンズは広角端において、
物体側から負の屈折力の第１群Ｌ１と、ある程度間隔を
隔てて合成屈折力が正の屈折力の第２群Ｌ２、更にある
程度間隔を隔てて負の屈折力の第３群Ｌ３を配置してい
る。このような負、正、負の屈折力の対称型的な光学配
置を広角端でとることにより、第２群Ｌ２の屈折力を強
めることができ、これにより広画角化及び小型化を達成
する際の諸収差の補正を良好に行えるようにしている。At the wide-angle end, the zoom lens of the present invention is
A first lens unit L1 having a negative refractive power, a second lens unit L2 having a positive combined refractive power and a third lens unit L3 having a negative refractive power are arranged at a certain distance from the object side. is doing. By taking such a symmetrical optical arrangement of negative, positive, and negative refracting powers at the wide-angle end, it is possible to strengthen the refracting power of the second lens unit L2, thereby achieving a wide angle of view and downsizing. When this is done, it is possible to favorably correct various aberrations.

【００２０】又、負の第１群Ｌ１と合成屈折力が正の第
２群Ｌ２とが、ある程度間隔を隔てて配置することによ
り、レトロフォーカスタイプの形態をとっており、これ
により広画角化の際に問題となるバックフォーカスの確
保を容易にしている。又第２群Ｌ２は物体側から正又は
負の屈折力を有する第２ａ群Ｌ２ａ、正又は負の屈折力
を有する第２ｂ群Ｌ２ｂ、負の屈折力を有する第２ｃ群
Ｌ２ｃ、正の屈折力を有する第２ｄ群Ｌ２ｄより構成し
ている。Further, the negative first lens unit L1 and the second lens unit L2 having a positive composite refractive power are arranged at a certain distance from each other to form a retrofocus type configuration, whereby a wide field angle is obtained. This makes it easy to secure the back focus, which is a problem when it comes to realization. The second lens unit L2 includes a second lens unit L2a having a positive or negative refractive power, a second lens unit L2b having a positive or negative refractive power, a second lens group L2c having a negative refractive power, and a positive refractive power from the object side. It is composed of the second group L2d having a.

【００２１】広角端から望遠端への変倍に際しては第２
ａ群Ｌ２ａと第２ｂ群Ｌ２ｂとの間隔が減少し、第２ｂ
群Ｌ２ｂと第２ｃ群Ｌ２ｃとの間隔が増大し、第２ｃ群
Ｌ２ｃと第２ｄ群Ｌ２ｄとの間隔が増大するように各レ
ンズ群を物体側へ移動させている。このとき広角端に比
べて望遠端において第２群の合成屈折力が弱くなるよう
に各レンズ群を物体側へ移動させている。第２群をこの
ように構成し、レンズ系全体として負、正、正、そして
負の構成のレンズ配置とすることにより、広画角化及び
高変倍化に伴う収差変動を良好に補正し、全変倍範囲に
わたり高い光学性能を得ている。Second, when changing the magnification from the wide-angle end to the telephoto end.
The distance between the a group L2a and the second b group L2b decreases,
Each lens group is moved toward the object side so that the distance between the group L2b and the second c group L2c increases and the distance between the second c group L2c and the second d group L2d increases. At this time, each lens unit is moved toward the object side so that the combined refractive power of the second unit becomes weaker at the telephoto end than at the wide-angle end. By constructing the second lens unit in this way and arranging the lens system to have a negative, positive, positive, and negative configuration as the entire lens system, it is possible to satisfactorily correct aberration fluctuations associated with widening of the angle of view and high zooming. , High optical performance over the entire zoom range.

【００２２】本発明では以上のように各要素を設定する
ことにより、広画角でしかも小型の高変倍比のズームレ
ンズを得ているが、更に好ましくは次の諸条件のうち少
なくとも１つを満足させるのが良い。According to the present invention, by setting each element as described above, a zoom lens having a wide angle of view and a small size and a high zoom ratio is obtained. More preferably, at least one of the following conditions is satisfied. Is good to satisfy.

【００２３】（１−イ）前記第３群の焦点距離をｆ３、
広角端における全系の焦点距離をｆｗとしたとき、 ０．９≦｜ｆｗ／ｆ３｜≦２．２ ・・・・・・（２） １．０≦ ｆｗ／ｆ２ｗ≦１．８ ・・・・・・（３） なる条件を満足することである。(1-a) The focal length of the third lens unit is f3,
When the focal length of the entire system at the wide angle end is fw, 0.9 ≦ | fw / f3 | ≦ 2.2 (2) 1.0 ≦ fw / f2w ≦ 1.8 ... (3) is to satisfy the condition.

【００２４】条件式（２）は第３群Ｌ３の屈折力に関す
るものである。条件式（２）の上限値を越えて第３群Ｌ
３の屈折力が強くなりすぎると、広角端において正のバ
ックフォーカス量を得るために、第３群Ｌ３の形状が限
定されるため諸収差を良好に補正するのが難しくなる。
また下限値を越えて第３群Ｌ３の屈折力が弱くなりすぎ
ると、変倍時に第３群Ｌ３による変倍効果が弱くなるた
め、結果として一定の変倍比を確保するためには各レン
ズ群の移動量を大きくしなければならず、この結果レン
ズ全長が増大してくるので良くない。Conditional expression (2) relates to the refractive power of the third lens unit L3. The upper limit of conditional expression (2) is exceeded and the third lens unit L is exceeded.
If the refractive power of 3 becomes too strong, it becomes difficult to satisfactorily correct various aberrations because the shape of the third lens unit L3 is limited in order to obtain a positive back focus amount at the wide-angle end.
If the lower limit is exceeded and the refractive power of the third lens unit L3 becomes too weak, the zooming effect of the third lens unit L3 becomes weak during zooming. As a result, in order to ensure a constant zoom ratio, each lens The amount of movement of the group must be increased, which results in an increase in the total lens length, which is not good.

【００２５】本発明において、更に良好な光学性能を達
成するためには、条件式（２）は以下の範囲をとること
が望ましい。In the present invention, it is desirable that conditional expression (2) be in the following range in order to achieve better optical performance.

【００２６】 １．０≦｜ｆｗ／ｆ３｜≦１．８ ・・・・・・（２ａ） 条件式（３）は第２群Ｌ２の屈折力に関するものであ
る。条件式（３）の上限値を越えて第２群Ｌ２の屈折力
が強くなりすぎると、第２群と第３群によるテレフォト
タイプの作用が強くなりすぎてしまい、バックフォーカ
スが確保しにくくなる。また条件式（３）の下限値を越
えて第２群Ｌ２の屈折力が弱くなりすぎると、広角端に
おいて一定の焦点距離を得るために負レンズ群の屈折力
を弱めることになり、結果としてレンズ全長が増大して
くるので良くない。1.0 ≦ | fw / f3 | ≦ 1.8 (2a) Conditional expression (3) relates to the refractive power of the second lens unit L2. When the upper limit of conditional expression (3) is exceeded and the refracting power of the second lens unit L2 becomes too strong, the telephoto type action of the second and third lens units becomes too strong, making it difficult to secure a back focus. Become. If the lower limit of conditional expression (3) is exceeded and the refracting power of the second lens unit L2 becomes too weak, the refracting power of the negative lens unit will be weakened in order to obtain a constant focal length at the wide-angle end. This is not good because the total lens length increases.

【００２７】条件式（３）は望ましくは以下の範囲を満
足すれば、更に非常に小型でありかつ高い光学性能を達
成することができる。If conditional expression (3) desirably satisfies the following range, it is possible to achieve a very small size and high optical performance.

【００２８】 １．１≦ ｆｗ／ｆ２ｗ≦１．５ ・・・・・・（３ａ） （１−ロ）広角端において前記第２Ｆ群と第２Ｒ群の合
成焦点距離を各々ｆ２Ｆｗ，ｆ２Ｒｗ、広角端における
全系の焦点距離をｆｗとするとき、 ０．５≦ｆｗ／ｆ２Ｆｗ≦１．７ ・・・・・・（４） ０．５≦ｆｗ／ｆ２Ｒｗ≦１．５ ・・・・・・（５） なる条件を満足することである。1.1 ≦ fw / f2w ≦ 1.5 (3a) (1-b) At the wide-angle end, the combined focal lengths of the second F group and the second R group are f2Fw, f2Rw, and wide angle, respectively. When the focal length of the entire system at the edge is fw, 0.5 ≦ fw / f2Fw ≦ 1.7 (4) 0.5 ≦ fw / f2Rw ≦ 1.5 (5) To satisfy the following condition.

【００２９】条件式（４），（５）の上限値を越えて第
２Ｆ群又は第２Ｒ群の屈折力が強くなりすぎると、広角
端におけるバックフォーカスの確保が困難になってく
る。また下限値を越えて第２Ｆ群又は第２Ｒ群の屈折力
が弱くなりすぎると、広角端で所定の焦点距離を得るた
めに負レンズ群の屈折力を弱めなければならず、結果と
してレンズ全長が長くなり小型化を達成することは難し
くなってくる。If the refractive power of the second F group or the second R group becomes too strong beyond the upper limits of the conditional expressions (4) and (5), it becomes difficult to secure the back focus at the wide angle end. If the lower limit value is exceeded and the refractive power of the second F group or the second R group becomes too weak, the refractive power of the negative lens group must be weakened to obtain a predetermined focal length at the wide-angle end, resulting in a total lens length. Will become longer and it will be difficult to achieve miniaturization.

【００３０】更に小型でありながらバックフォーカスを
確保でき、光学性能の良好なズームレンズを得るために
は条件式（４），（５）は以下の範囲をとるのが良い。In order to obtain a zoom lens having a small size and a good back focus and good optical performance, it is preferable that conditional expressions (4) and (5) fall within the following ranges.

【００３１】 ０．６≦ｆｗ／ｆ２Ｆｗ≦１．２ ・・・・・・（４ａ） ０．６≦ｆｗ／ｆ２Ｒｗ≦１．３ ・・・・・・（５ａ） （１−ハ）前記第２ｃ群と第２ｄ群の広角端と望遠端に
おける空気間隔を各々ＤＷc-d ，ＤＴc-d としたとき、 ＤＷc-d ＜ＤＴc-d ・・・・・・（６） なる条件を満足することである。0.6 ≦ fw / f2Fw ≦ 1.2 (4a) 0.6 ≦ fw / f2Rw ≦ 1.3 (5a) (1-c) When the air distances at the wide-angle end and the telephoto end of the 2c group and the 2d group are DW cd and DT cd , respectively, the condition that DW cd <DT cd (6) is satisfied.

【００３２】今、第１群（屈折力φ１）と第２群（屈折
力φ２）の２つのレンズ群より成り、双方のレンズ群の
間隔を変えて変倍を行う２群ズームレンズの合成屈折力
φ１２は双方のレンズ群の主点間隔をｅとすると、 φ１２＝φ１＋φ２−ｅ×φ１×φ２ ・・・・・・（ａ） となる。Now, the composite refraction of the two-group zoom lens is made up of two lens groups, a first group (refractive power φ1) and a second group (refractive power φ2), and zooms by varying the distance between both lens groups. The force φ12 is φ12 = φ1 + φ2-e × φ1 × φ2 (A), where e is the distance between the principal points of both lens groups.

【００３３】条件式（６）は広角端及び望遠端における
第２ｃ群と第２ｄ群のレンズ群間隔に関するものであ
る。（ａ）式よりわかるように、本来は望遠化の際は負
の屈折力の第２ｃ群と正の屈折力の第２ｄ群はその間隔
を狭めるのが良いといえる。しかしながら、そのような
レンズ群配置をとるとレンズ形態が望遠端において全体
的に非対称となってくるため良好な収差補正を行うこと
に対して不利となる。そのためズーム全域において良好
な諸収差特性を維持するためにはレンズ構成の枚数をを
増やさねばならなくなり、結局レンズ系の大型化をまね
いてしまう。そこで本発明では条件式（６）の如く設定
し、高変倍化を容易にすると共に諸収差を良好に補正し
ている。Conditional expression (6) relates to the lens group distance between the second group c and the second group d at the wide-angle end and the telephoto end. As can be seen from the equation (a), originally, it is preferable to narrow the distance between the second c-group of negative refracting power and the second d-group of positive refracting power at the time of telephoto. However, when such a lens group arrangement is adopted, the lens form becomes asymmetric at the telephoto end as a whole, which is disadvantageous for performing good aberration correction. Therefore, in order to maintain good various aberration characteristics in the entire zoom range, it is necessary to increase the number of lens components, which eventually leads to enlargement of the lens system. Therefore, in the present invention, the conditional expression (6) is set to facilitate high zooming and to satisfactorily correct various aberrations.

【００３４】（１−ニ）前記第２ｃ群の広角端と望遠端
での横倍率を各々βＷ2c，βＴ2cとしたとき、 ｜１／βＷ2c｜＜１．０ ・・・・・・（７） ｜１／βＴ2c｜＜１．０ ・・・・・・（８） なる条件を満足することである。(1-d) When the lateral magnifications at the wide-angle end and the telephoto end of the second group c are βW 2c and βT 2c , respectively, | 1 / βW 2c | <1.0 7) The condition of | 1 / βT 2c | <1.0 (8) is satisfied.

【００３５】条件式（７），（８）は少ないレンズ枚数
において小型で諸収差の補正が良好な光学系を得るため
のものである。最終レンズ面からのレンズ射出瞳の位置
は広角端より望遠端にてバックフォーカスが大となるた
め望遠端より物体側へ移動する。軸上収差と軸外収差の
バランスをとるためには瞳位置より離れているレンズ群
に入射される軸上光線と軸外光線の入射高をレンズ群間
隔変化により調整することが有効である。特に前記光線
は軸上より軸外での入射高をある程度大とすることが望
まれる。そのため望遠端においては、第２ｃ群と第２ｄ
群のレンズ群間隔は、前記した射出瞳の位置関係により
広角端より大とする必要がある。Conditional expressions (7) and (8) are for obtaining an optical system which is small in size and good in correction of various aberrations with a small number of lenses. The position of the lens exit pupil from the final lens surface moves to the object side from the telephoto end because the back focus becomes larger at the telephoto end than at the wide-angle end. In order to balance the on-axis aberration and the off-axis aberration, it is effective to adjust the incident heights of the on-axis ray and the off-axis ray that are incident on the lens groups that are far from the pupil position by changing the lens group spacing. In particular, it is desirable that the incident height of the light rays off-axis is rather large than on-axis. Therefore, at the telephoto end, the second group c and the second group d
The lens group interval of the groups needs to be larger than the wide-angle end due to the positional relationship of the exit pupil described above.

【００３６】しかしながら、このことは（ａ）式の関係
で述べたように望遠化に不利となってくる（減倍作用が
大となる）。そのため条件式（７），（８）を満足する
ように第２ｃ群の横倍率が縮小系とならない範囲での値
をとるのが良い。それにより広角端より望遠端において
第２ｃ群と第２ｄ群のレンズ群間隔が大となっても大き
な減倍作用を起こさず軸上収差と軸外収差のバランスを
ズーム全域において良好に保っている。However, this is disadvantageous for increasing the telephoto distance as described in the relation of the equation (a) (the demagnification effect becomes large). Therefore, it is preferable that the lateral magnification of the second group c is set to a value in a range that does not make a reduction system so as to satisfy the conditional expressions (7) and (8). As a result, even if the distance between the second group c and the second group d2 becomes large from the wide-angle end to the telephoto end, a large demagnifying action does not occur, and a good balance of axial aberration and off-axis aberration is maintained over the entire zoom range. .

【００３７】（１−ホ）広角端における前記第２群の横
倍率をβ２ｗとしたとき、 −０．６＜β２ｗ＜−０．１ ・・・・・・（９） なる条件を満足することである。(1-e) When the lateral magnification of the second group at the wide-angle end is β2w, the condition of -0.6 <β2w <-0.1 (9) should be satisfied. Is.

【００３８】条件式（９）は広角端における第２群の横
倍率に関するものである。条件式（９）の上限値を越え
ると広角端においてバックフォーカスが取りずらくな
り、結果として第３群のレンズ径の増大を招いてしま
う。また下限値を越えると一定の焦点距離を得るために
他のレンズ群の屈折力が限度を越えて強くなってしま
い、諸収差が多く発生してくるため良くない。Conditional expression (9) relates to the lateral magnification of the second lens unit at the wide-angle end. If the upper limit of conditional expression (9) is exceeded, it becomes difficult to obtain back focus at the wide-angle end, resulting in an increase in the lens diameter of the third lens group. On the other hand, if the value goes below the lower limit, the refracting power of the other lens units becomes stronger than the limit in order to obtain a fixed focal length, and various aberrations occur, which is not good.

【００３９】特に、諸収差の補正と小型化を両立するた
めには、望ましくは条件式（９）は以下の範囲をとるの
が良い。In particular, in order to achieve both the correction of various aberrations and the miniaturization, it is preferable that the conditional expression (9) be in the following range.

【００４０】 −０．５＜β２ｗ＜−０．１５ ・・・・・・（９ａ） （１−ヘ）前記第２Ｆ群と第２Ｒ群との間に絞りを配置
し、変倍と共に移動させたことである。-0.5 <β2w <-0.15 (9a) (1-f) An aperture stop is arranged between the second F group and the second R group, and moved together with zooming. That is.

【００４１】これにより入射瞳位置を適切に配置し、変
倍による収差変動を抑えている。尚、本発明において
は、絞りはＬ２群中であっても良い。また、絞りを変倍
に第２ｃ群と共に移動させる代わりに他のレンズ群と一
体に移動させても良い。Thus, the position of the entrance pupil is properly arranged, and the aberration variation due to the zooming is suppressed. Incidentally, in the present invention, the diaphragm may be in the L2 group. Further, the diaphragm may be moved integrally with the other lens group instead of being moved together with the second group c during zooming.

【００４２】（１−ト）第２Ｒ群の光軸より離れるに従
って正の屈折力を持つ少なくとも１つのレンズ面におい
て、その屈折力が弱まるような、或いは負の屈折力を持
つレンズ面においては、その屈折力が強まるような形状
の非球面を施すのが良い。これによれば、画面全体の光
学性能を更に向上させることができる。(1-g) At least one lens surface having a positive refracting power as the distance from the optical axis of the second R group becomes weaker, or at a lens surface having a negative refracting power, It is preferable to provide an aspherical surface having a shape that enhances the refractive power. According to this, the optical performance of the entire screen can be further improved.

【００４３】本発明におけるズームレンズにおいて、フ
ォーカシングはズーミング中、横倍率が等倍にならない
任意のレンズ群の使用が可能である。第１群がある程度
強い屈折力を有している場合、この第１群によってフォ
ーカスすればズーム全域中の任意の物体距離におけるフ
ォーカシング量を一定にできるため機構の簡略化を図る
のが好ましい。広角端において、バックフォーカスが十
分にあり、最終レンズ群が負の屈折力を持ち、その屈折
力がある程度強い場合には、最終レンズ群を像面側に移
動させるフォーカス方法が良い。In the zoom lens according to the present invention, for focusing, it is possible to use any lens group in which the lateral magnification does not become equal during zooming. When the first group has a certain degree of strong refracting power, focusing by this first group can make the focusing amount constant at an arbitrary object distance in the entire zoom range, so that it is preferable to simplify the mechanism. At the wide-angle end, when the back focus is sufficient, the final lens group has a negative refracting power, and the refracting power is strong to some extent, a focusing method of moving the final lens group to the image plane side is preferable.

【００４４】この際、第１群のレンズ外径の小型化が期
待できる。また第１群から最終レンズ群中の２つ以上の
レンズ群を同時に移動させる方法を用いても良い。また
フォーカス群が絞りを含む場合、絞りを光軸上固定状態
にして、フォーカス群を移動させることはフォーカス時
に絞り機構を移動させるための駆動トルクの低減を行う
ことができるので好ましい。At this time, it is expected that the outer diameter of the first lens group will be reduced. Further, a method of simultaneously moving two or more lens groups in the first lens group to the last lens group may be used. When the focus group includes a diaphragm, it is preferable to move the focus group while fixing the diaphragm on the optical axis because the driving torque for moving the diaphragm mechanism during focusing can be reduced.

【００４５】尚、本発明において第２群を物体側より順
に正、正、正、そして正の屈折力の４つのレンズ群、
負、負、負、そして正の屈折力の４つのレンズ群、正、
負、負、そして負の屈折力の４つのレンズ群、正、正、
負、そして負の屈折力の４つのレンズ群より構成しても
良い。In the present invention, the second lens group is composed of four lens groups of positive, positive, positive, and positive refractive power in order from the object side.
Four lens groups with negative, negative, negative, and positive refractive power, positive,
Negative, negative, and negative power four lens groups, positive, positive,
It may be composed of four lens groups having negative and negative refracting powers.

【００４６】次に本発明の数値実施例を示す。数値実施
例においてＲｉは物体側より順に第ｉ番目のレンズ面の
曲率半径、Ｄｉは物体側より第ｉ番目のレンズ厚及び空
気間隔、Ｎｉとνｉは各々物体側より順に第ｉ番目のレ
ンズのガラスの屈折率とアッベ数である。数値実施例に
おいて最終の２つのレンズ面はフェースプレートやフィ
ルター等のガラスブロックである。Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side in the i-th lens. The refractive index of glass and the Abbe number. In the numerical examples, the last two lens surfaces are glass blocks such as face plates and filters.

【００４７】又、前述の各条件式と数値実施例における
諸数値との関係を表−１に示す。Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples.

【００４８】非球面形状は光軸方向にＸ軸、光軸と垂直
方向にＨ軸、光の進行方向を正としＲを近軸曲率半径、
Ｋ，Ａ，Ｂ，Ｃ，Ｄを各々非球面係数としたとき、The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive light traveling direction, and R as a paraxial radius of curvature,
When K, A, B, C and D are aspherical coefficients,

【００４９】[0049]

【数１】 なる式で表わしている。[Equation 1] It is expressed by

【００５０】又「ｅ−０ｘ」は「１０-x」を意味してい
る。（数値実施例１） F= 28.17〜90.19 FNO= 3.64 〜9.00 2ω= 75.0°〜27.0° R 1= 690.43 D 1= 1.30 N 1=1.49699 ν 1= 81.6 R 2= 26.19 D 2=可変 R 3= 20.65 D 3= 2.30 N 2=1.77249 ν 2= 49.6 R 4= 23.31 D 4=可変 R 5= 14.34 D 5= 2.50 N 3=1.61800 ν 3= 63.4 R 6= 68.41 D 6=可変 R 7= 絞り D 7= 0.99 R 8= -25.73 D 8= 2.80 N 4=1.84665 ν 4= 23.8 R 9= -161.40 D 9=可変 R10= 1328.46 D10= 4.50 N 5=1.77249 ν 5= 49.6 R11= -16.85 D11=可変 R12= -14.43 D12= 1.80 N 6=1.60970 ν 6= 57.8 R13= -102.98"E-0x" means "10 -x ". (Numerical Example 1) F = 28.17 to 90.19 FNO = 3.64 to 9.00 2 ω = 75.0 ° to 27.0 ° R 1 = 690.43 D 1 = 1.30 N 1 = 1.49699 ν 1 = 81.6 R 2 = 26.19 D 2 = variable R 3 = 20.65 D 3 = 2.30 N 2 = 1.77249 ν 2 = 49.6 R 4 = 23.31 D 4 = Variable R 5 = 14.34 D 5 = 2.50 N 3 = 1.61800 ν 3 = 63.4 R 6 = 68.41 D 6 = Variable R 7 = Aperture D 7 = 0.99 R 8 = -25.73 D 8 = 2.80 N 4 = 1.84665 ν 4 = 23.8 R 9 = -161.40 D 9 = variable R10 = 1328.46 D10 = 4.50 N 5 = 1.77249 ν 5 = 49.6 R11 = -16.85 D11 = variable R12 = -14.43 D12 = 1.80 N 6 = 1.60970 ν 6 = 57.8 R13 = -102.98

【００５１】[0051]

【表１】 非球面係数 2面：K=-5.789e-02 A= 0 B= 6.189e-06 C=-8.330e-09 D= 6.659e-11 5面：K= 2.190e-01 A= 0 B= 1.507e-06 C= 3.397e-07 D=-8.543e-09 8面：K= 1.323e+01 A= 0 B= 2.082e-05 C=-8.274e-07 D= 8.719e-08 11面：K=-2.612e+00 A= 0 B=-4.988e-05 C=-1.792e-08 D=-1.183e-10 12面：K=-2.825e-01 A= 0 B= 3.173e-05 C=-1.666e-07 D= 3.858e-10 （数値実施例２） F= 28.84〜90.01 FNO= 3.46 〜9.00 2ω= 73.8°〜27.0° R 1= -65.83 D 1= 1.30 N 1=1.49699 ν 1= 81.6 R 2= 249.68 D 2=可変 R 3= -691.61 D 3= 1.60 N 2=1.49699 ν 2= 81.6 R 4= 54.33 D 4=可変 R 5= 13.16 D 5= 2.50 N 3=1.51633 ν 3= 64.2 R 6= -993.17 D 6=可変 R 7= 絞り D 7= 1.00 R 8= -19.61 D 8= 2.50 N 4=1.80518 ν 4= 25.4 R 9= -78.22 D 9=可変 R10=-2685.70 D10= 4.00 N 5=1.77249 ν 5= 49.6 R11= -15.54 D11=可変 R12= -14.51 D12= 1.80 N 6=1.63999 ν 6= 60.1 R13= -137.90[Table 1] Aspheric surface 2nd surface: K = -5.789e-02 A = 0 B = 6.189e-06 C = -8.330e-09 D = 6.659e-11 5th surface: K = 2.190e-01 A = 0 B = 1.507 e-06 C = 3.397e-07 D = -8.543e-09 8 side: K = 1.323e + 01 A = 0 B = 2.082e-05 C = -8.274e-07 D = 8.719e-08 11 side: K = -2.612e + 00 A = 0 B = -4.988e-05 C = -1.792e-08 D = -1.183e-10 12 side: K = -2.825e-01 A = 0 B = 3.173e-05 C = -1.666e-07 D = 3.858e-10 (Numerical example 2) F = 28.84 to 90.01 FNO = 3.46 to 9.00 2ω = 73.8 ° to 27.0 ° R 1 = -65.83 D 1 = 1.30 N 1 = 1.49699 ν 1 = 81.6 R 2 = 249.68 D 2 = Variable R 3 = -691.61 D 3 = 1.60 N 2 = 1.49699 ν 2 = 81.6 R 4 = 54.33 D 4 = Variable R 5 = 13.16 D 5 = 2.50 N 3 = 1.51633 ν 3 = 64.2 R 6 = -993.17 D 6 = Variable R 7 = Aperture D 7 = 1.00 R 8 = -19.61 D 8 = 2.50 N 4 = 1.80518 ν 4 = 25.4 R 9 = -78.22 D 9 = Variable R10 = -2685.70 D10 = 4.00 N 5 = 1.77249 ν 5 = 49.6 R11 = -15.54 D11 = Variable R12 = -14.51 D12 = 1.80 N 6 = 1.63999 ν 6 = 60.1 R13 = -137.90

【００５２】[0052]

【表２】 非球面係数 2面：K= 3.345e+02 A= 0 B=-6.074e-06 C=-1.144e-08 D=-1.574e-11 4面：K= 1.789e+01 A= 0 B=-7.283e-06 C=-4.857e-08 D=-8.630e-11 5面：K= 1.336e-01 A= 0 B= 0 C= 1.090e-07 D=-2.087e-09 8面：K= 6.635e+00 A= 0 B=-2.746e-06 C=-3.565e-08 D= 3.803e-08 11面：K=-9.879e-01 A= 0 B=-3.036e-05 C=-2.304e-08 D=-1.023e-09 12面：K=-2.850e-01 A= 0 B= 7.882e-06 C=-6.264e-08 D=-4.413e-11 （数値実施例３） F= 28.32〜90.13 FNO= 3.61 〜9.00 2ω= 74.8°〜27.0° R 1= 102.60 D 1= 1.60 N 1=1.49699 ν 1= 81.6 R 2= 31.00 D 2=可変 R 3= 220.75 D 3= 1.60 N 2=1.48749 ν 2= 70.2 R 4= 46.13 D 4=可変 R 5= 11.73 D 5= 2.80 N 3=1.51633 ν 3= 64.2 R 6= 127.74 D 6=可変 R 7= 絞り D 7= 1.35 R 8= -19.05 D 8= 2.80 N 4=1.80518 ν 4= 25.4 R 9= -73.28 D 9=可変 R10= 956.98 D10= 4.50 N 5=1.77249 ν 5= 49.6 R11= -16.14 D11=可変 R12= -15.53 D12= 1.80 N 6=1.63999 ν 6= 60.1 R13= -196.08[Table 2] Aspheric coefficient 2nd surface: K = 3.345e + 02 A = 0 B = -6.074e-06 C = -1.144e-08 D = -1.574e-11 4th surface: K = 1.789e + 01 A = 0 B = -7.283e-06 C = -4.857e-08 D = -8.630e-11 5th surface: K = 1.336e-01 A = 0 B = 0 C = 1.090e-07 D = -2.087e-09 8th surface: K = 6.635e + 00 A = 0 B = -2.746e-06 C = -3.565e-08 D = 3.803e-08 11 side: K = -9.879e-01 A = 0 B = -3.036e-05 C = -2.304e-08 D = -1.023e-09 12 side: K = -2.850e-01 A = 0 B = 7.882e-06 C = -6.264e-08 D = -4.413e-11 (Numerical example) 3) F = 28.32 to 90.13 FNO = 3.61 to 9.00 2 ω = 74.8 ° to 27.0 ° R 1 = 102.60 D 1 = 1.60 N 1 = 1.49699 ν 1 = 81.6 R 2 = 31.00 D 2 = variable R 3 = 220.75 D 3 = 1.60 N 2 = 1.48749 ν 2 = 70.2 R 4 = 46.13 D 4 = Variable R 5 = 11.73 D 5 = 2.80 N 3 = 1.51633 ν 3 = 64.2 R 6 = 127.74 D 6 = Variable R 7 = Aperture D 7 = 1.35 R 8 = -19.05 D 8 = 2.80 N 4 = 1.80518 ν 4 = 25.4 R 9 = -73.28 D 9 = variable R10 = 956.98 D10 = 4.50 N 5 = 1.77249 ν 5 = 49.6 R11 = -16.14 D11 = variable R12 = -15.53 D12 = 1.80 N 6 = 1.63999 ν 6 = 60.1 R13 = -196.08

【００５３】[0053]

【表３】 非球面係数 2面：K= 5.012e-01 A= 0 B=-5.015e-07 C= 2.129e-08 D= 9.775e-13 4面：K= 1.090e+00 A= 0 B=-1.301e-06 C=-2.099e-08 D=-3.339e-10 5面：K= 6.031e-03 A= 0 B=-1.005e-05 C= 1.109e-07 D=-2.227e-09 8面：K= 6.733e+00 A= 0 B= 4.456e-06 C= 2.597e-07 D= 3.168e-08 11面：K=-1.150e+00 A= 0 B=-2.883e-05 C=-3.543e-08 D= 3.957e-10 12面：K=-2.731e-01 A= 0 B= 1.062e-05 C=-1.954e-08 D= 2.997e-11 （数値実施例４） F= 30.00〜94.65 FNO= 3.27 〜10.00 2ω= 71.6°〜25.8° R 1= 68.48 D 1= 1.60 N 1=1.53171 ν 1= 48.9 R 2= 26.02 D 2=可変 R 3= 22.41 D 3= 3.50 N 2=1.60300 ν 2= 65.5 R 4= -166.95 D 4=可変 R 5= 35.84 D 5= 2.50 N 3=1.51822 ν 3= 59.0 R 6= 23.94 D 6=可変 R 7= 絞り D 7= 3.90 R 8= -35.74 D 8= 2.00 N 4=1.76182 ν 4= 26.5 R 9= -77.77 D 9=可変 R10= 58.70 D10= 4.50 N 5=1.72915 ν 5= 54.7 R11= -21.35 D11=可変 R12= -18.13 D12= 1.80 N 6=1.69679 ν 6= 55.5 R13= 155.55[Table 3] Aspherical coefficient 2 surface: K = 5.012e-01 A = 0 B = -5.015e-07 C = 2.129e-08 D = 9.775e-13 4 surface: K = 1.090e + 00 A = 0 B = -1.301 e-06 C = -2.099e-08 D = -3.339e-10 5 side: K = 6.031e-03 A = 0 B = -1.005e-05 C = 1.109e-07 D = -2.227e-09 8 Face: K = 6.733e + 00 A = 0 B = 4.456e-06 C = 2.597e-07 D = 3.168e-08 11 Face: K = -1.150e + 00 A = 0 B = -2.883e-05 C = -3.543e-08 D = 3.957e-10 12th surface: K = -2.731e-01 A = 0 B = 1.062e-05 C = -1.954e-08 D = 2.997e-11 (Numerical example 4) F = 30.00 to 94.65 FNO = 3.27 to 10.00 2 ω = 71.6 ° to 25.8 ° R 1 = 68.48 D 1 = 1.60 N 1 = 1.53171 ν 1 = 48.9 R 2 = 26.02 D 2 = variable R 3 = 22.41 D 3 = 3.50 N 2 = 1.60300 ν 2 = 65.5 R 4 = -166.95 D 4 = Variable R 5 = 35.84 D 5 = 2.50 N 3 = 1.51822 ν 3 = 59.0 R 6 = 23.94 D 6 = Variable R 7 = Aperture D 7 = 3.90 R 8 = -35.74 D 8 = 2.00 N 4 = 1.76182 ν 4 = 26.5 R 9 = -77.77 D 9 = variable R10 = 58.70 D10 = 4.50 N 5 = 1.72915 ν 5 = 54.7 R11 = -21.35 D11 = variable R12 = -18.13 D12 = 1.80 N 6 = 1.69679 ν 6 = 55.5 R13 = 155.55

【００５４】[0054]

【表４】 非球面係数 2面：K=-2.125e+00 A= 0 B= 2.249e-05 C= 2.949e-08 D= 6.979e-10 3面：K= 8.158e-01 A= 0 B=-8.155e-06 C= 3.714e-09 D= 6.233e-10 5面：K=-4.506e+00 A= 0 B=-3.222e-06 C= 2.563e-07 D=-1.031e-08 8面：K= 3.452e+01 A= 0 B= 1.358e-04 C= 1.630e-07 D= 7.988e-08 10面：K=-1.605e+01 A= 0 B=-1.283e-06 C=-3.407e-07 D= 2.543e-10 11面：K=-7.763e+00 A= 0 B=-4.113e-05 C=-1.022e-08 D=-1.826e-09 12面：K=-1.626e+00 A= 0 B= 4.315e-05 C=-3.382e-07 D= 6.583e-10[Table 4] Aspheric coefficient 2nd surface: K = -2.125e + 00 A = 0 B = 2.249e-05 C = 2.949e-08 D = 6.979e-10 3rd surface: K = 8.158e-01 A = 0 B = -8.155 e-06 C = 3.714e-09 D = 6.233e-10 5 sides: K = -4.506e + 00 A = 0 B = -3.222e-06 C = 2.563e-07 D = -1.031e-08 8 sides : K = 3.452e + 01 A = 0 B = 1.358e-04 C = 1.630e-07 D = 7.988e-08 10 side: K = -1.605e + 01 A = 0 B = -1.283e-06 C = -3.407e-07 D = 2.543e-10 11 side: K = -7.763e + 00 A = 0 B = -4.113e-05 C = -1.022e-08 D = -1.826e-09 12 side: K = -1.626e + 00 A = 0 B = 4.315e-05 C = -3.382e-07 D = 6.583e-10

【００５５】[0055]

【表５】 [Table 5]

【００５６】[0056]

【発明の効果】本発明によれば以上のように、複数のレ
ンズ群を有するズームレンズにおいて、例えば全体とし
て３つのグループのレンズ群に分けたズームレンズにお
いて各レンズ群のレンズ構成を適切に設定することによ
り、広画角化及び高変倍時に問題となってくる諸収差を
良好に補正しつつレンズ系全体の小型化を図った全変倍
範囲にわたり高い光学性能を有したズームレンズを達成
することができる。As described above, according to the present invention, in the zoom lens having a plurality of lens groups, for example, in the zoom lens divided into three lens groups as a whole, the lens configuration of each lens group is appropriately set. By doing so, we have achieved a zoom lens with high optical performance over the entire zoom range, which is aimed at reducing the overall size of the lens system while satisfactorily correcting various aberrations that become a problem when widening the angle of view and zooming. can do.

【図面の簡単な説明】[Brief description of drawings]

【図１】 本発明の実施例１の近軸屈折力配置の説明図FIG. 1 is an explanatory diagram of a paraxial refractive power arrangement according to a first embodiment of the present invention.

【図２】 本発明の実施例２の近軸屈折力配置の説明図FIG. 2 is an explanatory diagram of a paraxial refractive power arrangement according to a second embodiment of the present invention.

【図３】 本発明の実施例３の近軸屈折力配置の説明図FIG. 3 is an explanatory diagram of a paraxial refractive power arrangement according to a third embodiment of the present invention.

【図４】 本発明の実施例４の近軸屈折力配置の説明図FIG. 4 is an explanatory diagram of a paraxial refractive power arrangement according to Example 4 of the present invention.

【図５】 本発明の数値実施例１の広角端のレンズ断面
図FIG. 5 is a lens cross-sectional view at a wide-angle end according to Numerical Example 1 of the present invention.

【図６】 本発明の数値実施例２の広角端のレンズ断面
図FIG. 6 is a lens cross-sectional view at a wide-angle end according to Numerical Example 2 of the present invention.

【図７】 本発明の数値実施例３の広角端のレンズ断面
図FIG. 7 is a lens cross-sectional view at a wide-angle end according to Numerical Example 3 of the present invention.

【図８】 本発明の数値実施例４の広角端のレンズ断面
図FIG. 8 is a lens cross-sectional view at a wide-angle end according to Numerical Example 4 of the present invention.

【図９】 本発明の数値実施例１の広角端の収差図FIG. 9 is an aberration diagram at the wide-angle end according to Numerical Example 1 of the present invention.

【図１０】 本発明の数値実施例１の中間の収差図FIG. 10 is an intermediate aberration diagram of Numerical Example 1 of the present invention.

【図１１】 本発明の数値実施例１の望遠端の収差図FIG. 11 is an aberration diagram at a telephoto end according to Numerical Example 1 of the present invention.

【図１２】 本発明の数値実施例２の広角端の収差図FIG. 12 is an aberration diagram at a wide-angle end according to Numerical Example 2 of the present invention.

【図１３】 本発明の数値実施例２の中間の収差図FIG. 13 is an intermediate aberration diagram of Numerical example 2 of the present invention.

【図１４】 本発明の数値実施例２の望遠端の収差図FIG. 14 is an aberration diagram at a telephoto end according to Numerical Example 2 of the present invention.

【図１５】 本発明の数値実施例３の広角端の収差図FIG. 15 is an aberration diagram at a wide-angle end according to Numerical Example 3 of the present invention.

【図１６】 本発明の数値実施例３の中間の収差図FIG. 16 is an intermediate aberration diagram of Numerical example 3 of the present invention.

【図１７】 本発明の数値実施例３の望遠端の収差図FIG. 17 is an aberration diagram at a telephoto end according to Numerical Example 3 of the present invention.

【図１８】 本発明の数値実施例４の広角端の収差図FIG. 18 is an aberration diagram at a wide-angle end according to Numerical Example 4 of the present invention.

【図１９】 本発明の数値実施例４の中間の収差図FIG. 19 is an intermediate aberration diagram of Numerical Example 4 of the present invention.

【図２０】 本発明の数値実施例４の望遠端の収差図FIG. 20 is an aberration diagram at a telephoto end according to Numerical Example 4 of the present invention.

【符号の説明】[Explanation of symbols]

Ｌ１ 第１群 Ｌ２ 第２群 Ｌ２ａ 第２ａ群 Ｌ２ｂ 第２ｂ群 Ｌ２ｃ 第２ｃ群 Ｌ２ｄ 第２ｄ群 Ｌ３ 第３群 ＳＰ 絞り ＩＰ 像面 ｄ ｄ線 ｇ ｇ線 Ｓ．Ｃ 正弦条件 ΔＳ サジタル像面 ΔＭ メリディオナル像面 L1 1st group L2 2nd group L2a 2a group L2b 2b group L2c 2c group L2d 2d group L3 3rd group SP aperture IP image surface d d line g g line S. C Sine condition ΔS Sagittal image plane ΔM Meridional image plane

Claims (12)

【特許請求の範囲】[Claims] 【請求項１】 物体側より順に負の屈折力の第１群、正
の屈折力の第２群、そして負の屈折力の第３群の３つの
レンズ群を有し、該第２群は第２ａ群、第２ｂ群、第２
ｃ群、そして第２ｄ群の４つのレンズ群を有し、該第２
群中の４つのレンズ群の空気間隔を変えて変倍を行い、
該第２群の広角端と望遠端の合成焦点距離を各々ｆ２
ｗ，ｆ２Ｔとしたとき、 ｆ２ｗ＜ｆ２Ｔ なる条件を満足することを特徴とするズームレンズ。1. A three-lens group having, in order from the object side, a negative refractive power first group, a positive refractive power second group, and a negative refractive power third group, and the second lens group. 2a group, 2b group, 2nd
a group of four lenses, a group c and a group 2d,
Zooming is performed by changing the air spacing of the four lens groups in the group,
The combined focal lengths at the wide-angle end and the telephoto end of the second lens unit are f2, respectively.
A zoom lens characterized by satisfying a condition of f2w <f2T, where w and f2T. 【請求項２】 広角端において前記第２群を前記第２ａ
群と第２ｂ群より成る合成屈折力が正の第２Ｆ群、そし
て負の屈折力の第２ｃ群と正の屈折力の第２ｄ群より成
る合成屈折力が正の第２Ｒ群より構成したことを特徴と
する請求項１のズームレンズ。2. At the wide-angle end, the second group is moved to the second a
A second group F having a positive positive refractive power, a second group F having a positive refractive power, and a second group R having a positive positive refractive power, the second group C having a negative refractive power and the second group D having a positive refractive power The zoom lens according to claim 1, wherein 【請求項３】 前記第３群の焦点距離をｆ３、広角端に
おける全系の焦点距離をｆｗとしたとき、 ０．９≦｜ｆｗ／ｆ３｜≦２．２ １．０≦ ｆｗ／ｆ２ｗ≦１．８ なる条件を満足することを特徴とする請求項１のズーム
レンズ。3. When the focal length of the third lens unit is f3 and the focal length of the entire system at the wide angle end is fw, 0.9 ≦ | fw / f3 | ≦ 2.2 1.0 ≦ fw / f2w ≦ The zoom lens according to claim 1, wherein the zoom lens satisfies the condition of 1.8. 【請求項４】 広角端において前記第２Ｆ群と第２Ｒ群
の合成焦点距離を各々ｆ２Ｆｗ，ｆ２Ｒｗ、広角端にお
ける全系の焦点距離をｆｗとするとき、 ０．５≦ｆｗ／ｆ２Ｆｗ≦１．７ ０．５≦ｆｗ／ｆ２Ｒｗ≦１．５ なる条件を満足することを特徴とする請求項２のズーム
レンズ。4. When the combined focal lengths of the second F group and the second R group at the wide-angle end are f2Fw and f2Rw and the focal length of the entire system at the wide-angle end is fw, 0.5 ≦ fw / f2Fw ≦ 1. 7. The zoom lens according to claim 2, wherein the condition of 0.5 ≦ fw / f2Rw ≦ 1.5 is satisfied. 【請求項５】 前記第２ｃ群と第２ｄ群の広角端と望遠
端における空気間隔を各々ＤＷc-d ，ＤＴc-d としたと
き、 ＤＷc-d ＜ＤＴc-d なる条件を満足することを特徴とする請求項２のズーム
レンズ。5. Each of the air gap at the wide-angle end and the telephoto end of the first 2c group and the 2d group DW cd, when the DT cd, claims, characterized by satisfying the DW cd <DT cd condition: 2 zoom lens. 【請求項６】 前記第２ａ群は正の屈折力、前記第２ｂ
群は正の屈折力であることを特徴とする請求項２のズー
ムレンズ。6. The second group a has a positive refractive power, and the second group b has a positive refractive power.
The zoom lens according to claim 2, wherein the group has a positive refractive power. 【請求項７】 前記第２ａ群は正の屈折力、前記第２ｂ
群は負の屈折力であることを特徴とする請求項２のズー
ムレンズ。7. The second-a group has a positive refractive power, and the second-b group has a positive refractive power.
The zoom lens according to claim 2, wherein the group has a negative refractive power. 【請求項８】 前記第２ａ群は負の屈折力、前記第２ｂ
群は正の屈折力であることを特徴とする請求項２のズー
ムレンズ。8. The second group a has a negative refractive power, and the second group b has a negative refractive power.
The zoom lens according to claim 2, wherein the group has a positive refractive power. 【請求項９】 前記第２ｃ群の広角端と望遠端での横倍
率を各々βＷ2c ,βＴ2cとしたとき、 ｜１／βＷ2c｜＜１．０ ｜１／βＴ2c｜＜１．０ なる条件を満足することを特徴とする請求項４又は５の
ズームレンズ。9. When the lateral magnifications of the second lens group at the wide-angle end and the telephoto end are βW 2c and βT 2c , respectively, | 1 / βW 2c | <1.0 | 1 / βT 2c | <1.0 The zoom lens according to claim 4, wherein the following condition is satisfied. 【請求項１０】 広角端における前記第２群の横倍率を
β２ｗとしたとき、 −０．６＜β２ｗ＜−０．１ なる条件を満足することを特徴とする請求項１のズーム
レンズ。10. The zoom lens according to claim 1, wherein a condition of −0.6 <β2w <−0.1 is satisfied, where β2w is a lateral magnification of the second lens unit at the wide-angle end. 【請求項１１】 前記第２Ｆ群と第２Ｒ群との間に絞り
を配置し、変倍と共に移動させたことを特徴とする請求
項２のズームレンズ。11. The zoom lens according to claim 2, wherein an aperture stop is arranged between the second F group and the second R group, and the stop is moved together with zooming. 【請求項１２】 広角端から望遠端への変倍に際して、
前記第１群、前記第２群の４つのレンズ群、そして前記
第３群をいずれも物体側へ移動させていることを特徴と
する請求項１のズームレンズ。12. When zooming from the wide-angle end to the telephoto end,
The zoom lens according to claim 1, wherein all of the four lens groups of the first group, the second group, and the third group are moved to the object side.
JP15031794A 1993-07-14 1994-06-07 Zoom lens Expired - Fee Related JP3175484B2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP15031794A JP3175484B2 (en) 1994-06-07 1994-06-07 Zoom lens
US08/735,571 US5691851A (en) 1993-07-14 1996-10-23 Zoom lens

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP15031794A JP3175484B2 (en) 1994-06-07 1994-06-07 Zoom lens

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JPH07333504A true JPH07333504A (en) 1995-12-22
JP3175484B2 JP3175484B2 (en) 2001-06-11

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