JPS60225110A - Telephoto zoom lens - Google Patents

Abstract

PURPOSE:To obtain the compact zoom lens with a <=0.75 telephoto rate by composing the zoom lens of three lens groups with positive, negative, and positive power successively from the object side, and setting power of each group according to specific conditions. CONSTITUTION:The lens system consists of three groups, i.e. the 1st lens group f1 having positive refracting power, the 2nd lens group f2 having negative refracting power, and the 3rd lens group f3 with positive refracting power successively from the object side. The respective lens groups are moved mechanically and indenpendently of one another and meet requirements shown by inequalities, where fT is the focal length in a telephoto state, f1-f3 focal lengths of the 1st- the 3rd groups, and f3F and f3R the focal lengths of the front positive and rear negative lens groups of the 3rd groups. Further, beta2W and beta2T are image forming power values in the wide-angle and telephoto states of the 2nd group respectively, and beta3W and beta3T are image forming power values in the wide-angle and telephoto states of the 3rd group.

Description

【発明の詳細な説明】 本発明は１１１Ｍレフカメラ用の望遠ズームレンズに関
するものである。一般にテレ側の画角が１１７〜１２５
．ズーム比が２．３〜２９倍程度のズームレンズのテレ
比は０９以上であったが、本発明のズームレンズは物体
側から順に各レンズ群を正。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephoto zoom lens for a 111M reflex camera. Generally, the angle of view on the tele side is 117-125
．． The telephoto ratio of a zoom lens with a zoom ratio of about 2.3 to 29 times is 0.9 or higher, but in the zoom lens of the present invention, each lens group is adjusted sequentially from the object side.

負、正の３訂のパワーで栴成し上記条件の如く各りのパ
ワーを設定することによりテレ比０．７５以下とコンパ
クトなズームレンズを可能とする。By establishing three power levels, negative and positive, and setting each power according to the above conditions, a compact zoom lens with a telephoto ratio of 0.75 or less is made possible.

従来の望遠ズームレンズは一般にフォーカシング機能を
有する第１丁レンズ君＋、変倍機能を有する第２負レン
ズ群、ズーミングに際し像面を一定位置に補正させる機
能を有する＆Ｓ３正レンズ群。Conventional telephoto zoom lenses generally consist of a first lens group with a focusing function, a second negative lens group with a variable power function, and a positive lens group S3 with a function to correct the image plane to a fixed position during zooming.

結像のための第４正レンズ群で構成され、第１正レンズ
群と第４正レンズ群はズーミングに際し固定であり全長
変化はない。このためごの種のズームレンズの全長は変
倍糸の移動量と第４泊結像糸の望遠比によってはけ決め
られてしまう。したかってコンパクト化するためには、
第４群結像系の望遠比を小さくするか、ズーム部のパワ
ーを強め移動群の移動量を小さくするしかない。前者の
場合、過度のコンパクト化により結像系自体の収差補正
が困難になり少ないレンズ枚数では球面収差や非対称性
コマ収差などの補正かできなくなる。It is composed of a fourth positive lens group for image formation, and the first positive lens group and the fourth positive lens group are fixed during zooming and do not change in overall length. For this reason, the total length of the zoom lens is determined by the amount of movement of the variable magnification thread and the telephoto ratio of the fourth imaging thread. In order to make it more compact,
The only option is to reduce the telephoto ratio of the fourth group imaging system, or increase the power of the zoom section and reduce the amount of movement of the moving group. In the former case, excessive compactness makes it difficult to correct aberrations in the imaging system itself, and with a small number of lenses it is only possible to correct spherical aberrations, asymmetric coma, and the like.

また後者の場合、過度に強くなった負レンズ群のためペ
ッツバール和か負に増大し非点収差の補正がズーム全域
では困難になる。In the latter case, the Petzval sum becomes negative due to the excessively strong negative lens group, making it difficult to correct astigmatism over the entire zoom range.

本発明ではコンパクト化にホ要な役割を持つ第２詐変倍
系の変倍比を小さくシ、そのため損なわれた変倍量を従
来変倍作用がなかった第４群結像系を移動させることに
より、変倍作用を持たせ、なおかつ像位置補正の役割を
持つ第３計と結合することによりレンズ群を３群で構成
しコンパクト化に成功した。In the present invention, the magnification ratio of the second false variable magnification system, which plays an important role in compactness, is reduced, and the lost magnification amount is replaced by moving the fourth group imaging system, which conventionally had no variable magnification effect. By combining this with a third lens that has the function of varying magnification and correcting the image position, the lens group can be made up of three groups, successfully making it more compact.

本発明のレンズ系は物体側から順に正の屈折力を有する
第ルンズ群ｆ１．負の屈折力を有する第２レンズＪｉｆ
ｆ２．正の屈折力を有する第３レンズ群ｆ３の３Ｆで構
成され、各レンズ群がそれぞれ独立に機械的に移動する
ことを特徴とし、以下の条件を満たした極めてコンパク
トな望遠ズームレンズである。The lens system of the present invention has lens groups f1, . . . having positive refractive power in order from the object side. Second lens Jif with negative refractive power
f2. It is an extremely compact telephoto zoom lens that is composed of 3F of the third lens group f3 having a positive refractive power, and is characterized in that each lens group moves independently mechanically, and satisfies the following conditions.

（１）０．４＜ｆ、／ｆＴ＜０．６ （２）　０．１　＜　Ｉ　ｆｚ／　ｆＴｌ　＜０．１７
（３）　ｏ、　ｓ　ｓ　＜　ｌうｈ−去１　く１３（４
）　０．４　＜β２Ｗ／β２Ｔ　＜　０．６（５１０，
１＜　ｆ３　／　ｆＴ＜　０．２（６）”ｌ＜ｌ／：ｗ
　Ｉｓ茅Ｉく０３（７）　０．６　＜β３Ｗ／β３Ｔ　
＜　０．５（８）　０．８　＜　ｆ３ｐ　／　ｆ３＜　
１．３（９）　４．５＜　ｌ　ｆ３ｎ／　ｆ３１　＜ｓ
、ｓ但し ｆＴ：テレ時の焦点距離　ｆｌ：第１群の焦点距離ｆ２
：第２訃の焦点距＃１　ｆ３：第３１ｊ１の焦点距離ｒ
ｙ　：第３群前部正レンズＩ！ｉの焦点距離ｆ３Ｒ：第
３群後部負レンズ群の焦点距離β２ｗ：第２群ワイド時
の結像倍率 β２Ｔ：第２許テレ時の結像倍率 β３ｗ：第３群ワイド時の結像倍率 β３Ｔ：第３群テレ時の結像倍率 次に各条件式について説明を行なうと条件式（１）は１
群の屈折力を規定するものである。上限を越えると収差
補正は楽になるが、レンズ全長の増大を招き下限を越え
ると長焦点側での球面収差の補正を困難とし、フォーカ
シングの際の球面収差の変化を押さえることが困難にな
る。条件式（２）、　（３）。(1) 0.4<f, /fT<0.6 (2) 0.1<I fz/ fTl <0.17
(3) o, s s < luh - 1 ku13 (4
) 0.4 <β2W/β2T < 0.6 (510,
1< f3 / fT<0.2(6)”l<l/:w
Is茅Iku03(7) 0.6 <β3W/β3T
< 0.5 (8) 0.8 < f3p / f3 <
1.3(9) 4.5<l f3n/ f31<s
, s However, fT: Focal length in telephoto mode fl: Focal length of the first group f2
: 2nd focal length #1 f3: 31j1 focal length r
y: 3rd group front positive lens I! Focal length f3R of i: Focal length β2w of the rear negative lens group of the third group: Imaging magnification β2T when the second group is wide: Imaging magnification β3w when the second group is wide: Imaging magnification β3T when the third group is wide : Imaging magnification during 3rd group telephoto Next, we will explain each conditional expression. Conditional expression (1) is 1
This defines the refractive power of the group. Exceeding the upper limit makes it easier to correct aberrations, but exceeding the lower limit increases the overall length of the lens, making it difficult to correct spherical aberrations on the long focal length side, making it difficult to suppress changes in spherical aberrations during focusing. Conditional expressions (2) and (3).

（４）、は２ｔｒｆ、の屈折力及び移動量を規定する。(4) defines the refractive power and movement amount of 2trf.

（２）式の上限を越えると収差補正は楽になるが移動量
が大きくなりコンパクト化ができない。下限を越えると
ペッツバール和が過度に負になり非点収差の補正がズー
ム全域では困難になる。これを補正するためには３群の
負レンズ成分を弱くしなければならず条件式（８）　、
　（９）と相まってテレフォトタイプを崩すことになり
コンパクト化を実現できなくなる。また長焦点側での球
面の補正過剰及び軸外光束の下光線の色コマ補正が困難
になる。また（３）式及び（４）式の上限を越えると２
群における物点が大きく移動し、この群での収差補正を
困難にする。If the upper limit of equation (2) is exceeded, aberration correction becomes easier, but the amount of movement increases, making it impossible to make the lens compact. If the lower limit is exceeded, the Petzval sum becomes excessively negative, making it difficult to correct astigmatism over the entire zoom range. In order to correct this, the negative lens component of the third group must be weakened, and conditional expression (8),
Combined with (9), this destroys the telephoto type, making it impossible to achieve compactness. In addition, it becomes difficult to overcorrect the spherical surface on the long focal point side and to correct the color coma of the lower ray of the off-axis light beam. Also, if the upper limit of equations (3) and (4) is exceeded, 2
The object point in the group moves significantly, making it difficult to correct aberrations in this group.

また２群の変倍比が大きくなるほど歪曲収差の発生につ
ながるため好ましくない。（３）式及び（４）式の下限
を越えると歪曲収差などの補正は楽になるが全系として
のズーム比がかせげなくなり第３計のズーム比負世が大
きくなる。条件式（５）　、　（６）　、　（７）は３
　ＲＴの屈折力及び移動量を規定する。（５）式の下限
を越えるとコンパクト化には有利であるが長焦点側での
球面収差の補正か困難になる。また上限を越えると収差
補正は楽になるか、移動量が大きくなりコンパクト化で
きない。（６）式及び（７）式の上限を越えると３訃に
おける物点が大きく移動し、この群での収差補正を困難
とする。また（６）式及び（７）式の下限を越えると収
差補正（ｊ楽になるが全系としてのズーム比がかせげな
くなり、これを解消するならは２借のズーム比負世を太
きくしなけれはならず結果的に良好な収差補正をするこ
とができない。条件式（８）は３群にお１づる正レンズ
借に関するものである。下限を越えるとコンパクト化に
は有利であるが、止しンズ群自身の口径比が大きくなり
すぎて球面収差の補正を困却にする。上限を越えると３
群自身のテレ比か大きくなりコンパクト化できない。条
件式（９）は３訃における負レンズ群に関するものであ
る。下限を越えるとコンパクト化には有利であるが、ペ
ッツバール和か過度ニ負になり非点収差の補正が困難に
なる。上限を越えるとレンズ全長が長くなりコンパクト
化できない。Further, the larger the zoom ratio of the second lens group, the more distortion aberration occurs, which is not preferable. If the lower limit of equations (3) and (4) is exceeded, distortion and other aberrations can be easily corrected, but the zoom ratio of the entire system becomes unsatisfactory and the negative effect of the third zoom ratio increases. Conditional expressions (5), (6), and (7) are 3
Define the refractive power and movement amount of RT. If the lower limit of equation (5) is exceeded, it is advantageous for compactness, but it becomes difficult to correct spherical aberration on the long focal point side. Moreover, if the upper limit is exceeded, aberration correction will not be easy or the amount of movement will become large, making it impossible to make the lens compact. If the upper limits of equations (6) and (7) are exceeded, the object point at the third point will move significantly, making it difficult to correct aberrations in this group. In addition, if the lower limit of equations (6) and (7) is exceeded, aberration correction (J becomes easier, but the zoom ratio as a whole system becomes unsatisfactory, and in order to solve this problem, the zoom ratio disadvantage of 2) must be increased. Conditional expression (8) concerns the use of one positive lens in each of the three groups.Exceeding the lower limit is advantageous for compactness, but The aperture ratio of the lens group itself becomes too large, making it difficult to correct spherical aberration.If the upper limit is exceeded,
The telephoto ratio of the group itself becomes large and cannot be made compact. Conditional expression (9) relates to the negative lens group in the third case. If the lower limit is exceeded, it is advantageous for compactness, but the Petzval sum becomes excessively negative, making it difficult to correct astigmatism. If the upper limit is exceeded, the overall length of the lens becomes long and cannot be made compact.

以降に本発明の実施例を示す。但しｒ　ｔ、　ｄ　ｉ、
ｎ＋＋νｉはそれぞれ物体仙から順に数えた曲率半径、
レンズ面間１１４、ｄｍに対する屈折率、アツベ数であ
る。Examples of the present invention will be shown below. However, r t, d i,
n++νi is the radius of curvature counted in order from the object center,
These are the refractive index and Abbe number with respect to the distance between lens surfaces 114 and dm.

実施例 曲番号ｉ　ｒｉ　ｄｉ　ｉ　ν１ １　１０７．２０００　３．８５００　１．５１６８０
　６４．２２　−１４５０．００００　０．２０００３
　７９．４２００　１．９５００　１．８０５１８　２
５．５４　４７．８１００　６．３０００　１．５１６
８０　６４．２５　−１４５０．０ＯＯＯ可変 ６　−２０８．８７００　１．００００　１．６９６８
０　５５．５７　１８．９９８０　３．８６００　１．
８０５１８　２５．５８　４２．３１００　２．８５０
０ ９　−４２．００００　１．００００　１．６９６８Ｃ
５５，５１０３３６，９２００可変 １１　８５．７２００　４．５５００　１．６１２７２
　５８．６１２　−３１．１６００　１．００００　１
．７１７３６　２９．５１ａ　−５４，３５０００，２
０００ １４２７，６１５０５，１６００１，４８７４９７０，
４１５−８８，００００２，９４００ １６−５５，００００２，００００１，７５５２０２７
，５１７■　３６．１０００ １８　−１７．３０００　１，２７００　１．６９６８
０　５５．５１９　−３０．５０００　０．２０００２
０　７００．００００　２．４８００　１．７１７３６
　２９．５２１　−６８．００００ ｄ５　ｄｌ。Example song number i ri di i ν1 1 107.2000 3.8500 1.51680
64.22 -1450.0000 0.20003
79.4200 1.9500 1.80518 2
5.54 47.8100 6.3000 1.516
80 64.25 -1450.0OOO variable 6 -208.8700 1.0000 1.6968
0 55.57 18.9980 3.8600 1.
80518 25.58 42.3100 2.850
0 9 -42.0000 1.0000 1.6968C
55,510336,9200 variable 11 85.7200 4.5500 1.61272
58.612 -31.1600 1.0000 1
．． 71736 29.51a -54,35000,2
000 1427, 61505, 16001, 4874970,
415-88,00002,9400 16-55,00002,00001,7552027
,517■ 36.1000 18 -17.3000 1,2700 1.6968
0 55.519 -30.5000 0.20002
0 700.0000 2.4800 1.71736
29.521 -68.0000 d5 dl.

広角　０．９７２３　２０．３５４５ 中間　２５．１４　１０．３１ 望遠　３２．９７２２　１．９１３４ ｆｌ　／　ｆＴ＝０．５０　１ｆ２／　ｔＴｌ　＝Ｑ、
ｌ　３βｓｗ／β３Ｔ＝０．７１　ｆ３ｙ／　［３＝＝
　１．０１１ｆ３Ｒ／’相＝６３３Wide angle 0.9723 20.3545 Intermediate 25.14 10.31 Telephoto 32.9722 1.9134 fl/fT=0.50 1f2/tTl =Q,
l 3βsw/β3T=0.71 f3y/ [3==
1.011f3R/'phase=633

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

第１図は実施例の広角時の全レンズ構成図である。第２
図、第３図、第４図はそれぞれ実施例の物体距離無限大
における広角、中間、望遠時の収差図である。 特許出願人　株式会社　シ　グマ 代表者　山木道広 鞍 Ｃつ 表゛べ 守 ；・・） 七訳FIG. 1 is a diagram illustrating the entire lens configuration at a wide angle according to the embodiment. Second
3, and 4 are aberration diagrams of the embodiment at wide-angle, intermediate, and telephoto, respectively, at an infinite object distance. Patent applicant: Sigma Co., Ltd. Representative: Hirokura Yamaki

Claims (1)

【特許請求の範囲】 物体側から順に正の屈折力を有する第ルンズ群ｆｌ’＋
負の屈折力を有する第２レンズ計ｆ２．正の屈折力を有
する第３レンズ群ｆ３の３群で構成され各レンズ群が、
それぞれ独立に機械的に移動することを特徴とし、以下
の条件を満たした極めてコンパクトな望遠ズームレンズ
。 （１１０，４＜ｆ、／ｆＴ＜０．６ （４）０．４＜β２Ｗ／β２Ｔ　＜　０．６（５）　０
．１　＜　ｆ３　／　ｆＴ＜　０．２（６）０．１＜ｌ
アゎ一□、、ｌ　＜　０．３（７）　０．６　＜β３Ｗ
／β３Ｔ　＜　０．８（８）　０．８＜ｆ３Ｆ／　ｆｓ
＜１．３（９）　４．５　＜　ｌ　ｆｓＲ／　ｆａ　ｌ
　＜　８．５但し ｆＴ：テレ時の焦点距離　ｆｌ：第１群の焦点距離ｆ２
：第２群の焦点距離　ｆ３：＠３群の焦点距離ｆ３７　
：第３群前部正レンズ群の焦点距離ｔ３Ｒ：第３群彼都
負レンズ群の焦点距贋β２ｗ：第２詳ワイド時の結像倍
率 β２Ｔ：第２群テレ時の結像倍率 β３ｗ：第３群ワイド時の結像倍率 β３Ｔ：第３群テレ時の結像倍率[Claims] The first lens group fl'+ having positive refractive power in order from the object side.
A second lens meter f2. having negative refractive power. It is composed of three groups, the third lens group f3 having positive refractive power, and each lens group is
An extremely compact telephoto zoom lens that is characterized by its independent mechanical movement and meets the following conditions. (110,4<f, /fT<0.6 (4)0.4<β2W/β2T<0.6(5) 0
．． 1 < f3 / fT < 0.2 (6) 0.1 < l
A1□,,l < 0.3(7) 0.6 <β3W
/β3T < 0.8 (8) 0.8 < f3F/ fs
<1.3 (9) 4.5 < l fsR/ fa l
< 8.5 However, fT: Focal length in telephoto mode fl: Focal length of 1st group f2
: Focal length of the 2nd group f3: @ Focal length of the 3rd group f37
: Focal length of the front positive lens group of the 3rd group t3R: Focal length of the negative lens group of the 3rd group β2w: Imaging magnification β2T at 2nd detailed wide: Imaging magnification β3w at 2nd group telephoto: Imaging magnification β3T when the 3rd group is wide: Imaging magnification when the 3rd group is telephoto