JP2586627B2 - Two-group zoom lens - Google Patents

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明はレンズシャッターカメラ、ビデオカメラ等に
好適な２群ズームレンズに関し、特に全変倍範囲にわた
り収差補正を良好に行うと共にバックフォーカスの短縮
化、及びレンズ全長（第１レンズ面から像面までの距
離）の短縮化を図った変倍比2.5程度の２群ズームレン
ズに関するものである。Description: TECHNICAL FIELD The present invention relates to a two-unit zoom lens suitable for a lens shutter camera, a video camera, and the like, and more particularly, to favorably perform aberration correction over the entire zoom range and reduce back focus. More specifically, the present invention relates to a two-unit zoom lens having a zoom ratio of about 2.5, in which the overall length of the lens (the distance from the first lens surface to the image surface) is reduced.

（従来の技術） 最近レンズシャッターカメラ、ビデオカメラ等の小型
化に伴いレンズ全長の短い小型のズームレンズが要望さ
れている。特にレンズシャッターカメラ等のレンズ交換
を行なわない小型カメラの分野でもズームレンズの装着
が望まれ従来用いていた単焦点レンズと同程度の長さの
小型のズームレンズが要望されている。(Prior Art) Recently, with the miniaturization of lens shutter cameras, video cameras, and the like, a small zoom lens having a short overall lens length has been demanded. In particular, even in the field of a small camera such as a lens shutter camera which does not perform lens replacement, it is desired to mount a zoom lens, and a small zoom lens having the same length as a conventionally used single focus lens is demanded.

通常レンズシャッターカメラで多用されている標準画
角（撮影画角２ω＝47度で35mmスチルカメラに換算する
と焦点距離50mm程度）を含むズームレンズは、例えば特
公昭49−29146号公報をはじめ多数提案されている。こ
の種のズームレンズは物体側より順に負の屈折力の第１
レンズ群と正の屈折力の第２レンズ群の２つのレンズ群
より構成し、両レンズ群の間隔を変えて変倍するもので
あるが物体側より順に負と正の屈折力配置となっている
為にバックフォーカスが比較的長くなり一眼レフレック
スカメラとしては好ましい構成であるがレンズシャッタ
ーカメラとしてはレンズ全長が長すぎる傾向があった。Many zoom lenses including a standard angle of view (a focal length of about 50 mm when converted to a 35 mm still camera with a shooting angle of view of 2ω = 47 degrees and a 35 mm still camera) widely used in a lens shutter camera have been proposed, for example, Japanese Patent Publication No. 49-29146. Have been. This type of zoom lens has a first negative refractive power in order from the object side.
It is composed of two lens groups, a lens group and a second lens group having a positive refractive power. The magnification is changed by changing the distance between the two lens groups. However, negative and positive refractive powers are arranged in order from the object side. Therefore, the back focus is relatively long, which is a preferable configuration for a single-lens reflex camera, but the overall length of the lens tends to be too long for a lens shutter camera.

そこで本出願人は先に特開昭56−128911号公報や特開
昭57−201213号公報等において物体側より順に正の屈折
力の第１レンズ群と負の屈折力の第２レンズ群の２つの
レンズ群で構成し、両レンズ群の間隔を変えて変倍する
小型の所謂２群ズームレンズを提案した。Accordingly, the present applicant has previously disclosed in Japanese Patent Application Laid-Open Nos. 56-128911 and 57-201213 the first lens group having a positive refractive power and the second lens group having a negative refractive power in order from the object side. A small so-called two-unit zoom lens, which includes two lens units and changes the magnification by changing the distance between the two lens units, has been proposed.

同公報においては物体側より順に正、負の屈折力配置
を採用し望遠側とし、バックフォーカスを比較的短く
し、しかもレンズ全長の短縮化を図った変倍比1.5程度
のズームレンズを達成している。特開昭62−264019号公
報には前記ズームレンズを改良した２群ズームレンズを
開示している。In this publication, a positive / negative refractive power arrangement is adopted in order from the object side to the telephoto side, a back focus is relatively short, and a zoom lens with a zoom ratio of about 1.5 has been achieved which shortens the overall length of the lens. ing. Japanese Patent Laying-Open No. 62-264019 discloses a two-group zoom lens in which the above-mentioned zoom lens is improved.

一般に２群ズームレンズにおいて変倍比2.5程度を確
保しつつ、全変倍範囲にわたり収差変動を少なくして高
い光学性能を得ようとすると、各レンズ群、特に第２群
のレンズ枚数を増加させねばならず、レンズ系全体が大
型化する傾向があった。Generally, in order to obtain high optical performance by reducing aberration variation over the entire zoom range while securing a zoom ratio of about 2.5 in a two-unit zoom lens, the number of lenses in each lens group, particularly the second group, increases. And the entire lens system tends to be large.

（発明が解決しようとする問題点） 本発明は本出願人の先の特開昭56−128911号公報や特
開昭57−201213号公報等で提案した２群ズームレンズを
更に改良し、特に変倍比2.5程度と高変倍化を図りつつ
全変倍範囲にわたり収差変動を良好に補正した高い光学
性能を有したレンズ全長の短い２群ズームレンズの提供
を目的とする。(Problems to be Solved by the Invention) The present invention further improves the two-group zoom lens proposed in Japanese Patent Application Laid-Open Nos. 56-128911 and 57-201213 by the present applicant. It is an object of the present invention to provide a two-unit zoom lens having a short overall lens length and a high optical performance in which aberration variation is favorably corrected over the entire zoom range while achieving a high zoom ratio of about 2.5.

（問題点を解決するための手段） 本発明の２群ズームレンズは、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、両レンズ群の間隔を変えて変倍を行う２群ズーム
レンズにおいて、該第２群の変倍の際の移動量をΔ２、
全系の広角端と望遠端における焦点距離を各々fW,fT、
該第２群を構成する全てのレンズの材質の屈折率をN2
X、該第２群を構成する任意の正レンズと任意の負レン
ズの材質のアッベ数を各々ν2P,ν2Nとしたとき 0.7＜｜Δ2|/（fT−fW）＜1.0 ……（１） 1.55＜N2X＜1.74 ……（２） 53＜ν2N ……（３） ν2P＜40 ……（４） なる条件を満足することを特徴としている。(Means for Solving the Problems) The two-unit zoom lens of the present invention has two lens units, a first unit having a positive refractive power and a second unit having a negative refractive power, in order from the object side. In a two-unit zoom lens that changes the magnification by changing the distance between the lens groups, the amount of movement when changing the magnification of the second group is Δ2,
The focal lengths of the entire system at the wide-angle end and the telephoto end are respectively fW, fT,
The refractive index of the material of all the lenses constituting the second group is set to N2
X, when the Abbe numbers of the materials of the arbitrary positive lens and the arbitrary negative lens constituting the second group are ν2P and ν2N, respectively, 0.7 <| Δ2 | / (fT−fW) <1.0 (1) 1.55 <N2X <1.74 (2) 53 <ν2N (3) ν2P <40 (4) The following condition is satisfied.

特に本発明では第２群をいずれも物体側に凹面を向け
たメニスカス状の正レンズと３つのメニスカス状の負レ
ンズより構成していることを特徴としている。In particular, the present invention is characterized in that each of the second units comprises a meniscus-shaped positive lens having a concave surface facing the object side and three meniscus-shaped negative lenses.

（実施例） 第１図，第２図は本発明の数値実施例1,2のレンズ断
面図である。同図（Ａ）は広角端、同図（Ｂ）は望遠端
のズーム位置を示す。(Example) FIGS. 1 and 2 are lens cross-sectional views of Numerical Examples 1 and 2 of the present invention. FIG. 7A shows the zoom position at the wide angle end, and FIG. 7B shows the zoom position at the telephoto end.

図中、Ｉは正の屈折力の第１群、IIは負の屈折力の第
２群であり両レンズ群の間隔を減少させながら両レンズ
群を物体側へ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 figure, I is a first lens unit having a positive refractive power, and II is a second lens unit having a negative refractive power. By moving both lens units toward the object side as shown by arrows while reducing the distance between the two lens units, the wide-angle end is obtained. Zooming from to the telephoto end.

このようなタイプの２群ズームレンズは広角端でレン
ズ全長が最小となり望遠端で最大となる。本実施例では
カメラの携帯性を考慮し、広角端でのレンズ全長が最短
になるように設定している。In this type of two-unit zoom lens, the overall length of the lens becomes minimum at the wide-angle end and becomes maximum at the telephoto end. In this embodiment, in consideration of the portability of the camera, the total length of the lens at the wide-angle end is set to be the shortest.

そして本実施例では負の屈折力の第２群の変倍におけ
る移動量や第２群の各レンズの材質を前述の如く構成す
ることにより２群ズームレンズにおいて変倍比２以上を
達成する際に多く発生する広角側におけるコマ収差や変
倍に伴う球面収差、像面湾曲等を良好に補正している。In this embodiment, when the zoom ratio of 2 or more is achieved in the two-unit zoom lens by configuring the amount of movement of the second lens unit having negative refractive power during zooming and the material of each lens of the second unit as described above. Coma aberration on the wide-angle side, spherical aberration caused by zooming, curvature of field, and the like, which are frequently generated in the zoom lens, are satisfactorily corrected.

次に前述の各条件式の技術的意味について説明する。 Next, the technical meaning of each of the above conditional expressions will be described.

条件式（１）は変倍に伴う第２群の移動量と全系の焦
点距離の変化量との比を特定したものである。Conditional expression (1) specifies the ratio between the amount of movement of the second lens unit due to zooming and the amount of change in the focal length of the entire system.

一般に２つのレンズ群より成るレンズ系の場合、所謂
ニュートンの式を展開するとレンズ系のバックフォーカ
スSK′は２つのレンズ群の合成焦点距離をｆ、第１群の
屈折力をφ１、第１群と第２群の主点間隔をｅとすると SK′＝ｆ（１−φ1,e） ……（ａ） となる。条件式（１）で表わしている第２群の移動量Δ
２は望遠端でのバックフォーカスSK′Ｔと広角端でのバ
ックフォーカスSK′Ｗとの差に相当する。ここで広角端
と望遠端での第１群と第２群の主点間隔を各々eW,eTと
すると Δ２＝SK′Ｔ−SK′Ｗ ＝（fT−fW）−φ１（fT・eT−fW・eW） ……（ｂ） となる。（ｂ）式と条件式（１）を比較すると となる。（ｃ）式で条件式（１）を表わすと となる。（1a）式より明らかのように、この式（1a）は
移動量がΔ２である第２群には全く関係なく、第１群及
び広角端と望遠端における焦点距離と主点間隔で決まっ
てくる。In general, when a so-called Newton's equation is developed for a lens system including two lens groups, the back focus SK 'of the lens system is f, where the combined focal length of the two lens groups is f, the refractive power of the first group is φ1, and the first group is SK ′ = f (1−φ1, e) (a) where e is the principal point interval of the second group. Movement amount Δ of the second lens unit expressed by conditional expression (1)
2 corresponds to the difference between the back focus SK'T at the telephoto end and the back focus SK'W at the wide angle end. Here, assuming that the principal point intervals of the first lens unit and the second lens unit at the wide angle end and the telephoto end are eW and eT, respectively, Δ2 = SK′T−SK′W = (fT−fW) −φ1 (fT · eT−fW・ EW) …… (b) Comparing equation (b) with conditional equation (1) Becomes When the conditional expression (1) is expressed by the expression (c), Becomes As is evident from equation (1a), equation (1a) is completely independent of the second lens unit having a movement amount of Δ2, and is determined by the first lens unit and the focal length and principal point interval at the wide-angle end and the telephoto end. come.

条件式（１）はこのような事項を勘案されて規制され
たものであり、条件式（１）の上限値を越えると、即ち
条件式（1a）の下限値を越えると主点間隔eWが大きくな
りすぎ、又は第２群の移動量が多くなり、レンズ全長が
増大してくる。又条件式（１）の下限値を越えると、即
ち条件式（1a）の上限値を越えると所定の変倍比を得る
のが難しくなり、又は主点間隔eTが大きくなりすぎ望遠
側でのレンズ全長が増大してくるので良くない。Conditional expression (1) is regulated taking such matters into consideration. If the upper limit of conditional expression (1) is exceeded, that is, if the lower limit of conditional expression (1a) is exceeded, the principal point interval eW becomes larger. It becomes too large, or the amount of movement of the second group increases, and the overall length of the lens increases. If the lower limit of conditional expression (1) is exceeded, that is, if the upper limit of conditional expression (1a) is exceeded, it will be difficult to obtain a predetermined zoom ratio, or the principal point interval eT will be too large on the telephoto side. It is not good because the total lens length increases.

条件式（２）は第２群中に属する正レンズ及び負レン
ズの材質の屈折率の幅を制限するものである。本実施例
に係る２群ズームレンズでは第２群中の正レンズと負レ
ンズの材質の屈折率の差はなるべく少ない方が収差補正
上好ましく、条件式（２）はこの点から規制されたもの
であり、条件式（２）の下限値を越えるとペッツバール
和が小さくなりすぎ像面湾曲が補正過剰になると共に望
遠側で外向性コマが多く発生し、又広角側で正の歪曲収
差が増大してくるので良くない。又条件式（２）の上限
値を越えるとペッツバール和が大きくなりすぎ像面湾曲
が補正不足となり、特に変倍の中間領域において像面変
動が大きくなってくるので良くない。Conditional expression (2) limits the width of the refractive index of the material of the positive lens and the negative lens belonging to the second group. In the two-unit zoom lens according to the present embodiment, it is preferable in terms of aberration correction that the difference between the refractive indices of the materials of the positive lens and the negative lens in the second unit is as small as possible, and the conditional expression (2) is restricted from this point. If the lower limit of conditional expression (2) is exceeded, the Petzval sum becomes too small, the field curvature becomes excessively corrected, and more outward coma occur on the telephoto side, and the positive distortion increases on the wide-angle side. It is not good because it comes. If the value exceeds the upper limit of conditional expression (2), the Petzval sum becomes too large, and the field curvature becomes insufficiently corrected.

条件式（３），（４）は主に色収差の発生を少なく
し、特に倍率色収差の発生を少なくする為のものであ
る。条件式（３），（４）外れると変倍に伴う倍率色収
差の変動量が大きくなってくるので良くない。Conditional expressions (3) and (4) are intended mainly to reduce the occurrence of chromatic aberration, and particularly to reduce the occurrence of chromatic aberration of magnification. If conditional expressions (3) and (4) are not satisfied, the amount of change in chromatic aberration of magnification accompanying zooming becomes large, which is not good.

本実施例において更に変倍に伴う像面湾曲の変動を良
好に補正し、高い光学性能を維持しつつ、レンズ系全体
の小型化を図るには第２群を物体側に凹面を向けた全体
として４つのレンズより構成するのが良い。In the present embodiment, in order to further correct the fluctuation of the curvature of field due to zooming and to reduce the size of the entire lens system while maintaining high optical performance, the second lens unit must have a concave surface facing the object side. It is good to be composed of four lenses.

これは第１群近傍に配置した絞りに対して第２群の全
てのレンズがコンセントリックとなるようにする為の条
件であり、これにより変倍に伴う像面湾曲の変動を良好
に補正している。This is a condition for making all the lenses of the second group concentric with respect to the stop arranged in the vicinity of the first group, whereby the fluctuation of the field curvature due to zooming can be corrected well. ing.

そしてこのとき第２群中の４つのレンズを物体側から
順に１つの正レンズと３つの負レンズより構成するのが
特に広角端での負の歪曲収差を良好に補正するのに好ま
しい。At this time, it is preferable that the four lenses in the second group are composed of one positive lens and three negative lenses in order from the object side, in particular, in order to satisfactorily correct negative distortion at the wide-angle end.

更に歪曲収差や望遠側での外向性コマ、そして変倍に
伴う像面湾曲等を良好に補正するには第２群を物体側よ
り順に物体側に凹面を向けた正のメニスカス状の第21レ
ンズ、そして物体側に凹面を向けた負のメニスカス状の
第22レンズ、物体側に凹面を向けた負の第23レンズ、物
体側に凹面を向けた負のメニスカス状の第24レンズの全
体として４つのレンズより構成するのが良い。In order to satisfactorily correct distortion, extroverted coma on the telephoto side, and curvature of field due to zooming, the second lens unit should be a positive meniscus lens having a concave surface facing the object side in order from the object side. The lens, and the negative meniscus 22nd lens with the concave surface facing the object side, the negative 23rd lens with the concave surface facing the object side, and the negative meniscus 24th lens with the concave surface facing the object side as a whole It is better to be composed of four lenses.

第１群と第２群の２つのレンズ群で構成される２群ズ
ームレンズの合成焦点距離ｆは第１群と第２群の焦点距
離をf1,f2、第１群と第２群の主点間隔をｅとすると 1/f＝1/f1＋1/f2−e/f1・f2 ……（ｄ） となる。The combined focal length f of the two-unit zoom lens composed of two lens units, the first unit and the second unit, is f1 and f2, the focal length of the first unit and the second unit, and the main focal length of the first unit and the second unit. Assuming that the point interval is e, 1 / f = 1 / f1 + 1 / f2-e / f1 · f2 (d)

ここで焦点距離f1,f2は一定なので変倍変動は主点間
隔ｅの変化に依存する。変倍幅、即ち変倍比を大きくす
る為には広角端から望遠端までの主点間隔ｅの変化量を
大きくすれば良いが、そうすると一般にレンズ全長が増
大してくる。Here, since the focal lengths f1 and f2 are constant, the zooming variation depends on the variation of the principal point interval e. In order to increase the zooming width, that is, the zooming ratio, the amount of change in the principal point interval e from the wide-angle end to the telephoto end may be increased, but this generally increases the overall lens length.

この為、レンズ系全体の小型化を図りつつ変倍幅を拡
大するには（ｄ）式のe/f1,f2項において焦点距離f1,f2
の絶対値を小さくしておけば、少しの主点間隔ｅの変動
で合成焦点距離ｆを大きく変動させることができる。For this reason, in order to increase the zooming width while reducing the size of the entire lens system, the focal lengths f1 and f2 in the terms e / f1 and f2 in equation (d) are used.
If the absolute value of is small, the composite focal length f can be largely changed by a small change of the principal point interval e.

本発明における２群ズームレンズでは以上のことを勘
案して 0.55＜f1/fW＜0.85 ……（ｅ） 0.42＜|f2/fW|＜0.85 ……（ｆ） を満足させるのが良い。この（ｅ），（ｆ）式の上限値
を越えると、レンズ系が大型化してくる。又下限値を越
えると像面の倒れや各レンズ群の位置変動による像面の
変動が大きくなってくるので良くない。In consideration of the above, the two-unit zoom lens according to the present invention preferably satisfies 0.55 <f1 / fW <0.85 (e) 0.42 <| f2 / fW | <0.85 (f). Exceeding the upper limits of the expressions (e) and (f) causes the lens system to become large. On the other hand, if the value exceeds the lower limit, the image plane is greatly deteriorated due to the image plane tilting and the position fluctuation of each lens unit, which is not good.

更に本発明においては 0.8＜|f1/f2|＜1.5 ……（ｇ） なる条件を満足させるのが良い。これにより第２群の移
動量をあまり多くしなくても所定の変倍比を容易に得る
ことができる。上限値を越えるとレンズ系全体が大型化
し、又下限値を越えると全変倍範囲にわたり像面湾曲の
倒れが大きくなってくるので良くない。Further, in the present invention, it is preferable to satisfy the following condition: 0.8 <| f1 / f2 | <1.5 (g) Thus, a predetermined zoom ratio can be easily obtained without increasing the amount of movement of the second lens unit. If the value exceeds the upper limit, the entire lens system becomes large. If the value exceeds the lower limit, the field curvature becomes large over the entire zoom range, which is not good.

この他本発明において変倍比2.5程度で全変倍範囲に
わたり高い光学性能を確保する為には、第１群を物体側
に凸面を向けた正のメニスカス状の第11レンズ、両レン
ズ面が凹面の第12レンズ、両レンズ面が凸面の第13レン
ズ、そして１つ又は２つの正レンズの全体として４つの
レンズ又は５つのレンズより構成し、該第12レンズと第
13レンズとを接合又は独立して構成するのが良い。In addition to this, in order to ensure high optical performance over the entire zoom range at a zoom ratio of about 2.5 in the present invention, the first lens unit has a positive meniscus eleventh lens with the convex surface facing the object side, and both lens surfaces are The twelfth lens is composed of a twelfth lens having a concave surface, a thirteenth lens having both lens surfaces convex, and one or two positive lenses as a whole having four or five lenses.
It is better to join the 13 lenses or form them independently.

尚、本発明においてフォーカシングはレンズ系全体を
繰り出して行うのが収差変動が少なくて好ましいが第１
群若しくは第２群のみを移動させて行っても良い。これ
によればレンズ鏡筒が簡単となる。至近撮影の場合にの
み周辺部の光量不足を補う為に第２レンズ群のみを絞り
込んで行っても良い。In the present invention, it is preferable to perform focusing by extending the entire lens system because aberration variation is small.
It may be performed by moving only the group or the second group. This simplifies the lens barrel. Only in the case of close-up photography, only the second lens group may be stopped down to compensate for the lack of light amount in the peripheral portion.

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ν
ｉ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。Next, numerical examples of the present invention will be described. In numerical examples
Ri is the radius of curvature of the i-th lens surface in order from the object side,
Is the i-th lens thickness and air gap from the object side, Ni and ν
i is the refractive index and Abbe number of the glass of the i-th lens in order from the object side.

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-described conditional expressions and various numerical values in the numerical examples.

数値実施例１ F＝39.10 FNo＝1:3.27 ２ω＝57.9°〜29.2° 〜83.0 〜6.95 R 1＝ 20.88 D 1＝ 2.16 N 1＝1.68893 ν １＝31.1 R 2＝ 52.26 D 2＝ 1.92 R 3＝ -19.53 D 3＝ 5.00 N 2＝1.83400 ν ２＝37.2 R 4＝ 19.53 D 4＝ 3.10 N 3＝1.51633 ν ３＝64.1 R 5＝ -38.66 D 5＝ 0.35 R 6＝ 82.89 D 6＝ 2.67 N 4＝1.58913 ν ４＝61.2 R 7＝ -23.90 D 7＝ 0.15 R 8＝ 195.42 D 8＝ 2.30 N 5＝1.58913 ν ５＝61.2 R 9＝ -32.86 D 9＝ 1.20 R10＝ 絞り D10＝可変 R11＝ -58.33 D11＝ 3.00 N 6＝1.62004 ν ６＝36.3 R12＝ -20.71 D12＝ 3.16 R13＝ -17.92 D13＝ 1.10 N 7＝1.69680 ν ７＝55.5 R14＝‐191.67 D14＝ 1.65 R15＝ -32.64 D15＝ 1.50 N 8＝1.60311 ν ８＝60.7 R16＝ -47.65 D16＝ 1.93 R17＝ -23.01 D17＝ 1.30 N 9＝1.69680 ν ９＝55.5 R18＝ -52.15 数値実施例２ F＝ 39.5 FNo＝1:3.6 ２ω＝ 57.4°〜28.6° 〜84.8 〜7.7 R 1＝ 16.16 D 1＝ 2.25 N 1＝1.58267 ν １＝46.4 R 2＝ 65.30 D 2＝ 1.50 R 3＝ -18.38 D 3＝ 2.31 N 2＝1.72342 ν ２＝37.9 R 4＝ 25.47 D 4＝ 0.31 R 5＝ 41.86 D 5＝ 4.76 N 3＝1.51633 ν ３＝64.1 R 6＝ -16.80 D 6＝ 0.16 R 7＝ 64.91 D 7＝ 1.96 N 4＝1.56384 ν ４＝60.7 R 8＝ -30.00 D 8＝1.2 R 9＝ 絞り D 9＝可変 R10＝ -44.66 D10＝ 2.83 N 5＝1.62004 ν ５＝36.3 R11＝ -17.18 D11＝ 2.61 R12＝ -15.01 D12＝ 1.10 N 6＝1.69680 ν ６＝55.5 R13＝ -94.74 D13＝ 1.22 R14＝ -32.14 D14＝ 1.50 N 7＝1.60311 ν ７＝60.7 R15＝ -37.74 D15＝ 1.92 R16＝ -20.26 D16＝ 1.30 N 8＝1.69680 ν ８＝55.5 R17＝ -49.44 （発明の効果） 本発明によれば所定の屈折力の２つのレンズ群のレン
ズ構成を前述の如く特定して変倍を行うことによりレン
ズ全長の短い、所定の変倍比、及び撮影画角を有した高
い光学性能を有した２群ズームレンズを達成することが
できる。Numerical Example 1 F = 39.10 FNo = 1.3.27 2ω = 57.9 ° -29.2 ° -83.0-6.95 R 1 = 20.88 D 1 = 2.16 N 1 = 1.68893 ν 1 = 31.1 R 2 = 52.26 D 2 = 1.92 R 3 = -19.53 D 3 = 5.00 N 2 = 1.83400 ν 2 = 37.2 R 4 = 19.53 D 4 = 3.10 N 3 = 1.51633 ν 3 = 64.1 R 5 = -38.66 D 5 = 0.35 R 6 = 82.89 D 6 = 2.67 N 4 = 1.58913 ν 4 = 61.2 R 7 = -23.90 D 7 = 0.15 R 8 = 195.42 D 8 = 2.30 N 5 = 1.58913 ν 5 = 61.2 R 9 = -32.86 D 9 = 1.20 R10 = Aperture D10 = Variable R11 = -58.33 D11 = 3.00 N 6 = 1.62004 v 6 = 36.3 R12 = -20.71 D12 = 3.16 R13 = -17.92 D13 = 1.10 N 7 = 1.69680 v 7 = 55.5 R14 = -191.67 D14 = 1.65 R15 = -32.64 D15 = 1.50 N 8 = 1.60311 ν 8 = 60.7 R16 = -47.65 D16 = 1.93 R17 = -23.01 D17 = 1.30 N 9 = 1.69680 ν 9 = 55.5 R18 = -52.15 Numerical Example 2 F = 39.5 FNo = 1: 3.6 2ω = 57.4 ° to 28.6 ° 884.8 to 7.7 R 1 = 1.16 D 1 = 2.25 N 1 = 1.58267 ν 1 = 46.4 R 2 = 65.30 D 2 = 1.50 R 3 = -18.38 D 3 = 2.31 N 2 = 1.72342 ν 2 = 37.9 R 4 = 25.47 D 4 = 0.31 R 5 = 41.86 D 5 = 4.76 N 3 = 1.51633 ν 3 = 64.1 R 6 = -16.80 D 6 = 0.16 R 7 = 64.91 D 7 = 1.96 N 4 = 1.56384 ν 4 = 60.7 R 8 = -30.00 D 8 = 1.2 R 9 = Aperture D 9 = Variable R10 = -44.66 D10 = 2.83 N 5 = 1.62004 ν 5 = 36.3 R11 = -17.18 D11 = 2.61 R12 = -15.01 D12 = 1.10 N6 = 1.69680 ν6 = 55.5 R13 = -94.74 D13 = 1.22 R14 = -32.14 D14 = 1.50 N 7 = 1.60311 ν7 = 60.7 R15 = -37.74 D15 = 1.92 R16 = -20.26 D16 = 1.30 N 8 = 1.69690 v8 = 55.5 R17 = -49.44 (Effects of the Invention) According to the present invention, the lens configuration of the two lens units having a predetermined refractive power is specified as described above to perform zooming, so that the entire length of the lens is short, the zoom ratio is predetermined, and the photographing angle of view. It is possible to achieve a two-unit zoom lens having high optical performance having the following.

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

第１図，第２図は本発明の数値実施例１〜２のレンズ断
面図、第３図，第４図は本発明の数値実施例1,2の諸収
差図である。レンズ断面図において（Ａ）は広角端、
（Ｂ）は望遠端である。収差図において（Ａ）は広角
端、（Ｂ）は中間、（Ｃ）は望遠端の収差図である。 図中、I,IIは各々第1,第２群、矢印は変倍の際の各群の
移動方向を示す。1 and 2 are lens sectional views of Numerical Examples 1 and 2 of the present invention, and FIGS. 3 and 4 are aberration diagrams of Numerical Examples 1 and 2 of the present invention. In the lens sectional view, (A) is at the wide-angle end,
(B) is the telephoto end. In the aberration diagrams, (A) is an aberration diagram at the wide-angle end, (B) is an intermediate aberration diagram, and (C) is an aberration diagram at the telephoto end. In the figure, I and II indicate the first and second groups, respectively, and the arrow indicates the moving direction of each group during zooming.

Claims (5)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】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、両レンズ群の
間隔を変えて変倍を行う２群ズームレンズにおいて、該
第２群の変倍の際の移動量をΔ２、全系の広角端と望遠
端における焦点距離を各々fW,fT、該第２群を構成する
全てのレンズの材質の屈折率をN2X、該第２群を構成す
る任意の正レンズと任意の負レンズの材質のアッベ数を
各々ν2P,ν2Nとしたとき 0.7＜｜Δ2|/（fT−fW）＜1.0 1.55＜N2X＜1.74 53＜ν2N ν2P＜40 なる条件を満足することを特徴とする２群ズームレン
ズ。1. A two-unit zoom having two lens units, a first unit having a positive refractive power and a second unit having a negative refractive power, in order from the object side, and changing the distance between both lens units to perform zooming. In the lens, the moving amount at the time of zooming of the second group is Δ2, the focal lengths at the wide-angle end and the telephoto end of the entire system are fW and fT, respectively, and the refractive indices of the materials of all the lenses constituting the second group Is N2X, and Abbe numbers of the materials of the arbitrary positive lens and the arbitrary negative lens constituting the second group are ν2P and ν2N, respectively. 0.7 <| Δ2 | / (fT−fW) <1.0 1.55 <N2X <1.74 A two-unit zoom lens satisfying the following condition: 53 <ν2Nν2P <40. 【請求項２】前記第２群は物体側に凹面を向けた４つの
レンズより成っていることを特徴とする請求項１記載の
２群ズームレンズ。2. The two-unit zoom lens according to claim 1, wherein said second unit comprises four lenses each having a concave surface facing the object side. 【請求項３】前記第２群は１つの正レンズと３つの負レ
ンズより成っていることを特徴とする請求項２記載の２
群ズームレンズ。3. The second lens unit according to claim 2, wherein said second lens unit includes one positive lens and three negative lenses.
Group zoom lens. 【請求項４】前記第２群は物体側より順に１つの正レン
ズと３つの負レンズより成っていることを特徴とする請
求項２記載の２群ズームレンズ。4. The two-unit zoom lens according to claim 2, wherein said second unit comprises one positive lens and three negative lenses in order from the object side. 【請求項５】前記第２群は物体側より順に物体側に凹面
を向けた正のメニスカス状の第21レンズ、そして物体側
に凹面を向けた負のメニスカス状の第22レンズ、物体側
に凹面を向けた負の第23レンズ、物体側に凹面を向けた
負のメニスカス状の第24レンズより成っていることを特
徴とする請求項１記載の２群ズームレンズ。5. The second group includes a positive meniscus twenty-first lens having a concave surface facing the object side in order from the object side, a negative meniscus twenty-second lens having a concave surface facing the object side, and an object-side lens. 2. The two-unit zoom lens according to claim 1, comprising a negative twenty-third lens having a concave surface facing the lens, and a negative meniscus twenty-fourth lens having a concave surface facing the object side.