JPH03127012A

JPH03127012A - Compact zoom lens

Info

Publication number: JPH03127012A
Application number: JP26660689A
Authority: JP
Inventors: Hiroshi Umeda; 宏梅田; Sho Fukushima; 福島　省; Naoshi Okada; 尚士岡田; Junji Hashimura; 淳司橋村; Hisayuki Masumoto; 升本　久幸
Original assignee: Minolta Co Ltd
Current assignee: Minolta Co Ltd
Priority date: 1989-10-13
Filing date: 1989-10-13
Publication date: 1991-05-30
Anticipated expiration: 2012-04-30
Also published as: JP2605147B2

Abstract

PURPOSE:To compose the compact zoom lens for a lens shutter camera of a small number of lens elements by composing each of the front and rear groups of two lenses, and providing each group with at least one aspherical surface. CONSTITUTION:The zoom lens consists of the front group which has positive refracting power and the rear group which has negative refracting power in order from the object side and varies in total focal length by variation in the gap between the front and rear groups, and the front and rear groups each consists of two lenses and each have at least one aspherical surface. Consequently, while high optical performance is maintained, the compact zoom lens can be composed of a small number of lenses.

Description

【発明の詳細な説明】産呈±生凰里公立本発明はズームレンズに関するものであり、更に詳しく
はズームレンズ内蔵型レンズシャッターカメラ用のズー
ムレンズに関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom lens, and more particularly to a zoom lens for a lens shutter camera with a built-in zoom lens.

従来史技歪ズームレンズ内蔵型レンズシャッターカメラのコンパク
ト化，低コスト化を遠戚するために、撮影レンズのコン
パクト化．低コスト化が要望されている．ズーミングの
ための移動量も含め、レンズ系をコンパクト化するため
には、各群の屈折力を強くする必要があるが、性能を維
持しつつ屈折力を強くするというのは、レンズ枚数を増
加させる方向であると言える。一方、低コスト化のため
には、レンズ枚数を削減するのが効果的である。In order to closely resemble the compactness and cost reduction of conventional lens shutter cameras with built-in distortion zoom lenses, we have made the photographic lens more compact. There is a demand for lower costs. In order to make the lens system more compact, including the amount of movement for zooming, it is necessary to increase the refractive power of each group, but increasing the refractive power while maintaining performance requires increasing the number of lenses. It can be said that the direction is to On the other hand, in order to reduce costs, it is effective to reduce the number of lenses.

このように、レンズ系のコンパクト化と低コスト化には
、相反する要素が多分に含まれている。In this way, there are many conflicting elements involved in making a lens system more compact and reducing its cost.

ところで、最近、プラスチック底形やガラスモールド等
の技術進歩が著しく、非球面が安価に生産されうるよう
になってきている。By the way, recently, technological advances in plastic bottom shapes, glass molds, etc. have been remarkable, and aspheric surfaces can now be produced at low cost.

｛゜シよ゛と　る量斯る状況に鑑み、本発明の目的は、非球面を効果的に用
いることにより、コンパクトなレンズシャッターカメラ
用ズームレンズを、少ない枚数で構成することにある．
更に具体的には、ズーム比が２を越える上記ズームレン
ズを４群４枚構成で遠戚することにある。In view of this situation, an object of the present invention is to construct a compact zoom lens for a lens-shutter camera with a small number of lenses by effectively using an aspheric surface.
More specifically, the above-mentioned zoom lens having a zoom ratio exceeding 2 is arranged in a configuration of four elements in four groups.

゛　るための上記目的を達成するため本発明では、物体側より順に、
正屈折力を有する前群と，負屈折力を有する後群とから
成り、前群と後群との間隔を変化させることによって全
系の焦点距離を変化させるズームレンズにおいて、前記
前群及び後群がいずれも２枚のレンズから或ると共にそ
れぞれ非球面を少なくとも１面有する構成としている。In order to achieve the above-mentioned object, in the present invention, in order from the object side,
In a zoom lens that consists of a front group having a positive refractive power and a rear group having a negative refractive power, the focal length of the entire system is changed by changing the distance between the front group and the rear group. Each lens group is composed of two lenses, and each lens group has at least one aspherical surface.

前記前群中の非球面のうち少なくとも１面は、次の条件
式■を満足するように構成されているのが好ましい。It is preferable that at least one of the aspheric surfaces in the front group is configured to satisfy the following conditional expression (2).

非球面の最大有効径をｙ．、、とするとき、０．７ｙ，
□＜７＜　１．Ｏｙｖａ□なる任意の光軸垂直方向高さ
ｙに対して、｛ｘ　（ｙ）　　Ｘ＠（Ｆ）　）＜Ｏ　　・・・・−・
・・−・・・・−■ここで、６：前群の屈折力Ｎ：非球面の物体側媒質の屈折率Ｎ゛：非球面の像側媒質の屈折率ｘ　（ｙ）：非球面の面形状ｘｏ（ｙ）：非球面の参照球面形状但し、＋ΣＡｉ　ｙ　’ （２２ｒ：非球面の基準曲率半径 ε：２次曲面パラメータＡｉ：非球面係数？＝非球面の近軸曲率半径である。Let the maximum effective diameter of the aspherical surface be y. , , then 0.7y,
□＜7＜1. For any height y in the vertical direction of the optical axis such as Oyva□, {x (y) X@(F) )<O...
・・・・・− ■Here, 6: Refractive power of the front group N: Refractive index of the aspherical object-side medium N゛: Refractive index of the aspherical image-side medium x (y): Refractive index of the aspherical surface Surface shape xo(y): Reference spherical shape of the aspheric surface. However, +ΣAi y' (22 r: Reference radius of curvature of the aspheric surface ε: Quadratic surface parameter Ai: Aspheric coefficient?= Paraxial radius of curvature of the aspheric surface .

前記条件式のは、前群中の非球面が周辺はど正の屈折力
が弱く（負の屈折力が強く）なるということを意味し、
球面収差を補正するための条件である。上限を越えると
、球面収差がズーム全域で補正不足の傾向が著しくなり
、下限を越えると、球面収差がズーム全域で補正過剰の
傾向が著しくなる。The above conditional expression means that the positive refractive power becomes weaker (the negative refractive power becomes stronger) near the periphery of the aspherical surface in the front group,
This is a condition for correcting spherical aberration. When the upper limit is exceeded, spherical aberration tends to be undercorrected over the entire zoom range; when the lower limit is exceeded, the spherical aberration tends to be overcorrected over the entire zoom range.

また、前記後群中の非球面のうち少なくとも１面は、次
の条件式■を満足するように構成されているのが好まし
い０条件式■は、非球面の最大有効径を）’　ｍａｗと
するとき、０．８　ｙ　ａｓ、＜ｙ＜１．。Furthermore, it is preferable that at least one of the aspherical surfaces in the rear group be configured to satisfy the following conditional expression (2).The conditional expression (2) preferably defines the maximum effective diameter of the aspherical surface as )' maw. When 0.8 y as, <y<1. .

Ｖ−ａ□なる任意の光軸垂直方向高さｙに対して、−ｏ
、ｉｏ＜ｑ・（Ｎ”−Ｎ）・　、。For any vertical height y of the optical axis V-a□, -o
, io<q・(N”−N)・ ,.

（ｘ　（ｙ）　　ｘｏ（ｙ）　／＜Ｏ・−−−−−−−
・・・−・・−■ここで、ｈ：後群の屈折力である。(x (y) xo(y) /<O・---------
...--■ Here, h: Refractive power of the rear group.

前記条件式■は、後群中の非球面が周辺はど負の一屈折
力が弱く　（正の屈折力が強く）なるということを意味
し、歪曲収差と像面湾曲とをバランスよく補正するため
の条件である。上限を越えると、広角端における歪曲収
差が正の大きな値をとるようになり、下限を越えると、
ズーム全域で像面が負の方向に湾曲する傾向が著しくな
る。The above conditional expression (■) means that the aspheric surface in the rear group has a weak negative refractive power (a strong positive refractive power) at the periphery, and corrects distortion and curvature of field in a well-balanced manner. This is the condition for When the upper limit is exceeded, the distortion at the wide-angle end takes on a large positive value, and when the lower limit is exceeded,
There is a significant tendency for the image plane to curve in the negative direction over the entire zoom range.

前群中のすべての非球面は、次の条件式■を満足するこ
とが望ましい。It is desirable that all the aspheric surfaces in the front group satisfy the following conditional expression (2).

条件式■は、非球面の最大有効径を７１１１１Ｍとする
とき、ｙ　＜　０．７ｙｓｍｘなる任意の光軸垂直方向
高さｙに対して、 −０，０２＜馴（Ｎ’−Ｎ）・　、。Conditional expression (2) is: -0,02<(N'-N)・, for any height y in the vertical direction of the optical axis where y<0.7ysmx, when the maximum effective diameter of the aspherical surface is 71111M. .

（ｘ　　（ｙ’）　−ｘ＋（ｙ）　　）＜ｏ、ｏｔ　　
−・−・−・−・・・・−・■である。(x (y') −x+(y) )<o, ot
−・−・−・−・・・・−・■.

条件式〇の上限を越えると、輪帯球面収差が負の大きな
値を持つようになり、絞り込みによるピント位置のずれ
が問題となる。また、下限を越えると、輪帯光束に対す
る球面収差補正効果が過剰となり、諸収差と球面収差を
バランスよく補正するのが困難となり、球面収差が波う
ったような形になりやすくなる。If the upper limit of conditional expression (0) is exceeded, the annular spherical aberration will have a large negative value, and a shift in the focus position due to aperture will become a problem. If the lower limit is exceeded, the effect of correcting the spherical aberration on the annular beam becomes excessive, making it difficult to correct various aberrations and spherical aberration in a well-balanced manner, and the spherical aberration tends to take on an undulating shape.

後群中のすべての非球面は、次の条件式■を満足するこ
とが望ましい。It is desirable that all the aspheric surfaces in the rear group satisfy the following conditional expression (2).

条件式■は、非球面の最大有効径をｙ、、８とするとき
、７＜　０．Ｂｙ＋＋−ａｘなる任意の光軸垂直方向高
さｙに対して、 −０，０５＜９’、・　（Ｎ’　　−Ｎ）　　・　、。Conditional formula (2) is such that, when the maximum effective diameter of the aspherical surface is y, 8, 7<0. For any height y in the vertical direction of the optical axis, By++-ax, -0,05<9', .(N'-N) .

（ｘ（ｙ）−ｘａ（ｙ）７＜０．０２　　−・−・・−
−−−■である。(x(y)−xa(y)7<0.02 −・−・・−
---■.

条件式■の上限を越えると、広角端〜中間焦点距離領域
の中間画角帯において、正の歪曲収差及び像面湾曲の正
偏移傾向が大きくなる。また、下限を越えると、中間焦
点距離域〜望遠端で、負の歪曲収差が大きくなり、加え
て全ズーム域で像面湾曲の負偏移傾向が著しくなる。When the upper limit of conditional expression (2) is exceeded, the tendency for positive distortion and positive deviation of the curvature of field increases in the intermediate field angle band from the wide-angle end to the intermediate focal length region. Further, when the lower limit is exceeded, negative distortion becomes large from the intermediate focal length range to the telephoto end, and in addition, the negative shift tendency of the curvature of field becomes significant in the entire zoom range.

前記前群を構成するレンズが次の条件式■■を満足する
ように構成されているのが好ましい。It is preferable that the lenses constituting the front group be constructed so as to satisfy the following conditional expression (2).

νｄ　（Ｇ１１　＜４０　　−　・−・・・・−−−−
−−一−−−−−・■νｄ　（Ｇり　＞５０　　−・・
・−・−・・−・・−一−−−・−・・・・■但し、 νｄ　＜ａｎ　：前記前群を構成する物体側のレンズの
アツベ数 νｄ　、、＞　：前記後群を構成する像側のレンズのア
ツベ数である。νd (G11 <40 − ・−・・・・−−−−
−−1−−−−・■νd (Gri >50 −・・
・−・−・・−・・−１−−−・−・・・・・・■ However, νd <an: Atsube number νd of the object side lens forming the front group,,>: The lens forming the rear group This is the Abbe number of the image-side lens.

上記条件式■■は軸上色収差１倍率色収差を補正するた
めの条件である。−νｄ＋＋＋＋を小さくし、νｄ　（
Ｇりを大きくすることにより、色収差補正を行う。The above conditional expression (■■) is a condition for correcting longitudinal chromatic aberration and lateral chromatic aberration. -νd++++ is made small, and νd (
Chromatic aberration is corrected by increasing G.

また、バックフォーカスを適度の大きさに保つために、
前記前群は、物体側より順に、負レンズ及び正レンズか
ら構成されているのが好ましい。Also, in order to keep the back focus at an appropriate size,
Preferably, the front group includes a negative lens and a positive lens in order from the object side.

バックフォーカスが短かくなりすぎると、最も像面側の
レンズの光路有効径が大きくなりすぎるために、カメラ
が大型化してしまう。If the back focus becomes too short, the effective diameter of the optical path of the lens closest to the image plane becomes too large, resulting in an increase in the size of the camera.

裏１Ｌ班以下、本発明に係るコンパクトなズームレンズの実施例
を示す。In the back section 1L, examples of the compact zoom lens according to the present invention will be shown.

但し、各実施例において、ｒ、〜ｒ、は物体側から数え
た面の曲率半径、ｄ　Ｉ””　ｄ　ｔは物体側から数え
た軸上面間隔を示し、Ｎ、〜Ｎ４＋　ν１〜ν、は物体
側から数えた各レンズのｄ線に対する屈折率、アツベ数
を示す、また、ｆは全系の焦点距離、ＦＩＩＧは開放Ｆ
ナンバーを示す。However, in each example, r, ~r, is the radius of curvature of the surface counted from the object side, d I"" d t is the axial surface spacing counted from the object side, and N, ~N4+ ν1 ~ ν, is Indicates the refractive index and Atsube number of each lens for the d-line counted from the object side. Also, f is the focal length of the entire system, and FIIG is the open F
Show the number.

なお、実施例中、曲率半径に＊印を付した面は非球面で
構成された面であることを示し、前記非球面の面形状（
ｘ（ｙ））を表わす式で定義するものとする。In addition, in the examples, a surface with a radius of curvature marked with * indicates that it is an aspherical surface, and the surface shape of the aspherical surface (
x(y)).

〈実施例１〉ｆ寡２９．θ〜４４，２〜６７．５Ｆ工。＝３．６〜５．５〜８．４ Σｄ　＝３５．６２４〜４４．８７３〜６４．５０８非
１４む４敗ｒｌ　　：　　　ｔ　−０，８８０４７Ａａ　−−０，
９１０８１ｘ　１０−　’Ａｓ””０．６３１９５Ｘ１
０−’ ａｓ　−−０，８６０７８Ｘ　１０−”ｒ８：　　　ε
雪０．８８９２５Ａａ−０，４７９５３ｘｌＯ−’ Ａｈ”０．１８７８９Ｘ１０−’ Ａ、麿−０，１１７４７Ｘ１０−・ｒｓ　：ｔ　−０，９４６９７Ａ４＝０．２１８６９Ｘ１０−’ Ａ、＝０．８０７８８Ｘ１０−＠＾ｓ＝０．７４４２３Ｘ１０−’ ε＝０．９２８５８Ａ４−０．１６０１１ｘｌＯ−’ Ａａ−−０，１７１１７ｘｌＯ−’ Ａｍ＝０．２５８７８Ｘ１０−” ｅ　−０，５３１２７＾ａ＝　　０．３９６０２Ｘ１０−’ Ａｈ　””　−０，５７９１０Ｘ　１０−　’Ａ＠＝０
．１７８３３Ｘ１０−” 〈実施例２〉ｆ冨３６．２〜５３．０〜７７．５ＦＮＯ＝３．６〜５．３〜７．８１１、ｔｌＵＵ４１、’／４９１０５０、ｕυ ｒ・ −５２，３９７ Σｄ麿３２．９５８〜４２．９８６〜６１．０３８農１
４む遣欧ｒ、：　　　ε陶０．９９９７４＾、　−−０，１１４５８ｘ　１０−　”ｓ、−０，５
５３５１ｘｌＯ″６＾、諭−０．３６５４８Ｘ１０−’ ＾ｑ−０，２０８３６ＸＩＯ−マ＾−識−０，２５９５０Ｘ１Ｇ−” Ａ、巽−０，２６７２２ｘｌＯ引０ＡＩ＠　　票−０，２２４７８Ｘ１０−”Ａ＊＋　　−
０，８７１０６ＸＩＯ−”Ａ、雪０．７０９６５ｘ１０
−目ｒ寞：　　　ｇ　−０，９９５３３Ａａ−０，３８６７３ＸｌＯ−’ Ａｓ　”　０．７７８９４　Ｘ　１０−もＡａ−０，４
４８８１ｘｌＯ−’ Ａｔ−０，５６８７８Ｘ　１０−’ Ａｓ”０．５２４０２Ｘ１Ｇ−” Ａ９−０．２４１７７Ｘ１０−’。<Example 1> f-29. θ~44, 2~67.5 F engineering. = 3.6 ~ 5.5 ~ 8.4 Σd = 35.624 ~ 44.873 ~ 64.508 non-14 4 loss rl: t -0,88047Aa --0,
91081x 10-'As””0.63195X1
0-' as −-0,86078X 10-”r8: ε
Snow 0.88925 Aa-0,47953xlO-'Ah"0.18789X10-' A, Maro-0,11747X10-・rs: t -0,94697 A4=0.21869X10-' A,=0.80788X10-@ ＾ s=0.74423X10-' ε=0.92858 A4-0.16011xlO-'Aa--0,17117xlO-'Am=0.25878X10-" e -0,53127 ^a= 0.39602X10-' Ah "" -0,57910X 10- 'A@=0
．． 17833 52,397 Σdmaro 32.958~42.986~61.038 Agriculture 1
4 times 0.99974 ^, −−0,11458x 10−”s, −0,5
5351xlO"6 ^, Satoshi-0.36548X10-'^q-0,20836XIO-Ma^-Sense-0,25950X1G-" A, Tatsumi-0,26722xlO minus 0 AI@ vote-0,22478X10-"A*+ −
0,87106XIO-”A, snow 0.70965x10
-Eye: g -0,99533 Aa-0,38673XlO-' As ” 0.77894 X 10- also Aa-0,4
4881xlO-' At-0,56878X 10-'As"0.52402X1G-"A9-0.24177X10-'.

Ａｌｌ　　−０，１５３２１Ｘ１０−”Ａｌｌ　　−一
０．２０６６０Ｘ１０−’コｒ４　：ｒＳ　：Ａｌｌ　　＝−０，７２５１９Ｘ１０−ＩＳε＝０．１
０４６０Ｘ１０Ａａ＝０．２３０４３Ｘ１０−’ Ａｓ　＝　−０，４８５４０ｘ　ｌＯ−’Ａ６＝−０．
１０８４６ＸｌＯ−’ Ａ、＝０．３３３０９ＸＩＯ−” Ａｓ＝０．５９１４１Ｘ１０〜９ＡＩ　＝　−０，５３３３０Ｘ　１０−　”＾、。＝　
−０，４８３３５Ｘ　１０−　’　ＩＡ＋＋　　＝　　
０．６３４０８Ｘ１０−”八＋ｚ　　＝　　０．６２２
１３Ｘ１０−１５ε＝０．９９９６６Ａ、＝０．６６２４３ＸＩＯ−’ ＾ｓｚ　Ｏ，２４１６６Ｘ１０−’ ＡＩ、＝０．６０７０６ＸＩＯ−’ Ａ、＝０．３３７０８Ｘ１０−’ Ａａ＝０．２５４９９ｘｌＯ−” Ａ、＝０．４６８５７Ｘ１０引ＯＡ１゜＝−０，２０２１７Ｘ１０−＋Ａｌｌ　　＝０．１０１３５Ｘ１０−”Ａ口＝　−０，
５３１３４Ｘ　１０−　”〈実施例３〉ｆ　＝３９．３〜５８．５〜８６．６Ｆｓｏ＝３．６〜５．４〜８．０ Σｄ　＝３４．１８１〜４５．７１０〜６６．６２０韮
豊凰係歎ｒｔ　　：　　　ｔ　＝０．９４４５２＾ａ＝　　０．
１５５５９Ｘ１０−” Ａ６＝−０，５１６８１ｘ１０−’ Ａｓ”　　０．５１７３８Ｘ１０−” Ａ１゜モ０．２４６１５ｘ１０−’ Ａｃｔ　　＝　　０．３６５１１ｘｌＯ−”ｒｔ　：　
　ε冨０．９８５４５＾ａ　＝　０．１１３０９Ｘ１０−” Ａ６冨−０，６６４７４Ｘ１０−’ ＾ｓ　＝　０．４３８３３　ｘ　１０−　＠ｒ４　：ｒＳ　：Ａｇｏ　　＝０．２５２４２Ｘ１０伺０＾ｒ　ｚ　＝　
０．９０９６５　Ｘ　１０−口ｅ　＝０．１２１９０ｘ
１０Ａ、＝０．４５３３９Ｘ１０−’ ＡＩ、＝０．１５８３０Ｘ１０−’ ＾ａ　＝　０．５１４６４　Ｘ　１０−９Ａ１゜＝０．
１１０８５Ｘ１０−” Ａ１□　＝−０，２８６７８Ｘ１０−”ε＝０．９７６
７７Ａ、＝０．５１７３０Ｘ１０−’ １、＝−０，９１６１２Ｘ１０−’ ａｍ＝０．５９１５２ｘｌＯ−” Ａ１゜＝−０，３４３２３Ｘ１０−” Ａｌｔ　　＝０．２０４０９Ｘ１０−目〈実施例４〉ｆ　＝３９．３〜５８．５〜８６．６ＦＮＯ＝３．６〜５．４〜８．０ Σｄ　＝３６．３６５〜４８．６７１〜７０．９９０去
Ｉ４む４致ｒ、　　：　　　ｅ　＝０．９４５７８Ａ４　＝　−０
，１３６９１ｘ　１０−’ａｂ＝−０．２３５７５ｘｌ
Ｏ−’ Ａ１１＝−０，５３９２７Ｘ１０−” Ａ、・　冨０．２４０４８Ｘ１０−９Ａｃｔ　　−０，３６８８５Ｘ１０−”ｒ、：　　　ｇ
　＝０．９９９７０Ａ４＝−０，６１８０８ｘ１０〜４Ａ＆＝０．２７９０４Ｘ　１０−’ Ａｓ＝０．３５４８０ｘｌＯ−” Ａｇｏ　　−０，１７１６０ｘｌＯ−１ＯＡ＋ｉ　＝０
．５７３９９Ｘ１０−Ｉ３ｒａ　　：　　　ｔ　＝０．
１１２２０Ｘ１０Ａ、＝０．２６８５８ｘｌＯ〜４Ａ＆−０，１０７０６ｘｌＯ−’ Ａ・＝０．５２６５２Ｘ１０−” Ａｇｏ　　＝０．１２６９７Ｘ１０−”Ａｃｔ　　＝　
　０．９１９８９Ｘ１０−１４ｒｓ　　：　　　ｅ　＝
０．９７８５９Ａ、＝０．５１０９８Ｘ１０−’ Ａ６＝−０，３５８２２Ｘ１０−’ Ａａ＝０．５５４１８Ｘ１０−” Ａ、。＝　−０，２７２２９Ｘ　１０−　”Ａｕｇ　　
＝　　０．１３６４８ｘｌＯ−”第１図〜第４図は、前
記実施例１〜４に対応するレンズ構成図である。All -0, 15321
0460X10 Aa=0.23043X10-' As=-0,48540x lO-'A6=-0.
10846XIO-' A, = 0.33309XIO-'' As = 0.59141X10~9 AI = -0,53330X 10-''^,. =
-0,48335X 10-' IA++ =
0.63408X10-”8+z = 0.622
13X10-15ε=0.99966 A,=0.66243XIO-' ^sz O,24166X10-'AI,=0.60706XIO-'A,=0.33708X10-'Aa=0.25499xlO-" A,=0. 46857X10-0 A1゜=-0, 20217X10-+ All =0.10135X10-”A port=-0,
53134 RT: t =0.94452^a= 0.
15559X10-"A6=-0,51681x10-'As"0.51738X10-"A1゜mo0.24615x10-' Act = 0.36511xlO-"rt:
εFu0.98545 ^a = 0.11309X10-"A6Fu-0,66474X10-' ^s = 0.43833 x 10- @r4 : rS : Ago =0.25242X10Ki0^r z =
0.90965 x 10-mouth e = 0.12190x
10 A, = 0.45339X10-' AI, = 0.15830X10-' ^a = 0.51464 X 10-9A1° = 0.
11085X10-” A1□ =-0, 28678X10-”ε=0.976
77 A. 3 ~ 58.5 ~ 86.6 FNO = 3.6 ~ 5.4 ~ 8.0 Σd = 36.365 ~ 48.671 ~ 70.990 left I4 m4 match r, : e = 0.94578 A4 = - 0
, 13691x 10-'ab=-0.23575xl
O-'A11=-0,53927X10-" A,・Tength 0.24048X10-9 Act -0,36885X10-"r,: g
=0.99970 A4=-0,61808x10~4 A&=0.27904X 10-'As=0.35480xlO-" Ago -0,17160xlO-1OA+i =0
．． 57399X10-I3ra: t=0.
11220X10A, =0.26858xlO~4 A&-0,10706xlO-'A.=0.52652X10-"Ago=0.12697X10-"Act =
0.91989X10-14rs: e=
0.97859A,=0.51098X10-'A6=-0,35822X10-'Aa=0.55418X10-" A,.=-0,27229X 10-"Aug
= 0.13648xlO-'' FIGS. 1 to 4 are lens configuration diagrams corresponding to Examples 1 to 4.

尚、第１図〜第４図中、矢印は前記前群及び後群の最広
角端（Ｓ）から置型遠端（Ｌ）にかけての移動を模式的
に示している。Note that in FIGS. 1 to 4, arrows schematically indicate movement of the front group and the rear group from the widest angle end (S) to the stationary far end (L).

実施例１は物体側より順に、両凹の負の第１レンズ及び
両凸の正の第２レンズから威る前群と、第３レンズ及び
第４レンズから成る後群とから構成されている。前記第
３レンズは、ノンパワーに近い正のレンズで構成され、
また第４レンズは、物体側に凹の負メニスカスレンズで
構成されている。尚、負の第１レンズの物体側の面及び
像側の面、正の第２レンズの像側の面、正の第３レンズ
の物体側の面並びに負の第４レンズの物体側め面は非球
面である。Embodiment 1 is composed of, in order from the object side, a front group consisting of a biconcave negative first lens and a biconvex positive second lens, and a rear group consisting of a third lens and a fourth lens. . The third lens is composed of a positive lens with close to non-power,
The fourth lens is a negative meniscus lens that is concave on the object side. In addition, the object side surface and the image side surface of the negative first lens, the image side surface of the positive second lens, the object side surface of the positive third lens, and the object side surface of the negative fourth lens. is an aspherical surface.

実施例２は物体側より順に、像側に凹の負メニスカスレ
ンズより成る第１レンズ及び両凸の正の第２レンズから
成る前群と、第３レンズ及び第４レンズから戒る後群と
から構成されている。前記第３レンズは、ノンパワーに
近い正のレンズで構成され、また第４レンズは、物体側
に凹の負メニスカスレンズで構成されている。尚、負の
第１レンズの物体側の面及び像側の面、正の第２レンズ
の像側の面並びに正の第３レンズの物体側の面は非球面
である。Embodiment 2 includes, in order from the object side, a front group consisting of a first lens consisting of a negative meniscus lens concave to the image side and a positive biconvex second lens, and a rear group consisting of a third lens and a fourth lens. It consists of The third lens is composed of a positive lens with almost no power, and the fourth lens is composed of a negative meniscus lens that is concave on the object side. Note that the object-side surface and image-side surface of the negative first lens, the image-side surface of the positive second lens, and the object-side surface of the positive third lens are aspherical surfaces.

実施例３は物体側より順に、像側に凹の負メニスカスレ
ンズより成る第１レンズ及び両凸の正の第２レンズから
成る前群と、第３レンズ及び第４レンズから成る後群と
から構成されている。前記第３レンズは、ノンパワーに
近い正のレンズで構成され、また第４レンズは、物体側
に凹の負メニスカスレンズで構成されている。尚、負の
第１レンズの物体側の面及び像側の面、正の第２レンズ
の像側の面並びに正の第３レンズの物体側の面は非球面
である。Embodiment 3 consists of, in order from the object side, a front group consisting of a first lens consisting of a negative meniscus lens concave to the image side and a positive biconvex second lens, and a rear group consisting of a third lens and a fourth lens. It is configured. The third lens is composed of a positive lens with almost no power, and the fourth lens is composed of a negative meniscus lens that is concave on the object side. Note that the object-side surface and image-side surface of the negative first lens, the image-side surface of the positive second lens, and the object-side surface of the positive third lens are aspherical surfaces.

実施例４は物体側より順に、像側に凹の負メニスカスレ
ンズより成る第１レンズ及び両凸の正の第２レンズから
成る前群と、第３レンズ及び第４レンズから成る後群と
から構成されている。前記第３レンズでは、ノンパワー
に近い正のレンズで構成され、また第４レンズは、物体
側に凹の負メニスカスレンズで構成されている。尚、負
の第１レンズの物体側の面及び像側の面、正の第２レン
ズの像側の面並びに正の第３レンズの物体側の面は非球
面である。Embodiment 4 consists of, in order from the object side, a front group consisting of a first lens consisting of a negative meniscus lens concave to the image side and a positive biconvex second lens, and a rear group consisting of a third lens and a fourth lens. It is configured. The third lens is composed of a positive lens with almost no power, and the fourth lens is composed of a negative meniscus lens that is concave on the object side. Note that the object-side surface and image-side surface of the negative first lens, the image-side surface of the positive second lens, and the object-side surface of the positive third lens are aspherical surfaces.

第５図〜第８図は前記実施例１〜４に対応する収差図で
、それぞれ（Ｓ）は広角端焦点距離、（Ｍ）は中間焦点
距離、（Ｌ〉　は望遠端焦点距離での収差を示している
。また、実線（ｄ）はｄ線に対する収差を表わし、点ｆ
％Ｉ　（ＳＣ）は正弦条件を表わす、更に点線（ＤＭ）
と実線（Ｏ５）はメリディオナル面とサジタル面での非
点収差をそれぞれ表わしている。Figures 5 to 8 are aberration diagrams corresponding to Examples 1 to 4, in which (S) is the aberration at the wide-angle end focal length, (M) is the intermediate focal length, and (L> is the aberration at the telephoto end focal length). In addition, the solid line (d) represents the aberration for the d-line, and the point f
%I (SC) represents the sine condition, and the dotted line (DM)
and the solid line (O5) represent astigmatism on the meridional plane and the sagittal plane, respectively.

第１表〜第４表はそれぞれ実施例１〜４に対応して、前
記ｙの値に対する各非球面における条件式■■中の凱・（Ｎ’ −Ｎ）ｄ。Tables 1 to 4 correspond to Examples 1 to 4, respectively, and show the values of Kai·(N' −N) d in the conditional formula (■■) for each aspherical surface for the value of y.

ｙ　Ｘｘ＜ｙ＞Ｘｏ（ｙ））。y　Xx <y> Xo(y) ).

条件式■■中のへ・（Ｎ’ −Ｎ）いる。Conditional expression (N’ -N) There is.

また、第５表は実施例１〜４における条件式■中のνｄ（、。Also, Table 5 shows νd(,) in conditional expression (2) in Examples 1-4.

条件式■中のνｄ０２）の値を示している。Indicates the value of νd02) in conditional expression ■ ing.

第１表（実施例１）第表（実施例２）第表（実皓例　３）第４表（実施例４）第５表上記のように実施例１〜４は、およそ焦点距離が３８〜
９０ＩＩＩｌｌの仕様を中心としている。従来のこの仕
様のズームレンズは、７〜８枚程度のレンズで構成され
ている。斯るズームレンズとしては、例えば７枚のレン
ズ構成において１面の非球面が用いられたもの等がある
。Table 1 (Example 1) Table (Example 2) Table (Actual Example 3) Table 4 (Example 4) Table 5 As mentioned above, Examples 1 to 4 have a focal length of approximately 38 ~
It focuses on the specifications of 90IIIll. A conventional zoom lens with this specification is composed of about seven to eight lenses. Such a zoom lens includes, for example, one in which one aspherical surface is used in a seven-lens configuration.

ところが、本発明によれば非球面が前・後群のそれぞれ
に少なくとも１面用いられているため、レンズの構成枚
数を４枚とし、レンズ全長を短縮することが可能となる
。However, according to the present invention, since at least one aspherical surface is used in each of the front and rear groups, it is possible to reduce the number of lenses to four and shorten the total length of the lens.

光豐坐盟来以上説明したように、本発明によれば高い光学性能を維
持しながら、少ない枚数のレンズでコンパクトなズーム
レンズを実現することができる。As described above, according to the present invention, it is possible to realize a compact zoom lens with a small number of lenses while maintaining high optical performance.

例えば、ズーム比が２を越える上記ズームレンズを４群
４枚構成で実現することができる。また、本発明に係る
ズームレンズを、ズームレンズ内蔵型レンズシャッター
カメラに適用すれば、該カメラのコンパクト化、低コス
ト化を遠戚することができる。For example, the above zoom lens having a zoom ratio exceeding 2 can be realized with a configuration of four elements in four groups. Moreover, if the zoom lens according to the present invention is applied to a lens shutter camera with a built-in zoom lens, the camera can be made more compact and cost-effective.

[Brief explanation of the drawing]

第１図、第２図、第３図及び第４図は、それれ本発明の
実施例１〜４に対応するレンズ構成！である。第５図、
第６図、第７図及び第８図は、それぞれ実施例１〜４に
対応する収差図である。FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are lens configurations corresponding to Examples 1 to 4 of the present invention! It is. Figure 5,
FIG. 6, FIG. 7, and FIG. 8 are aberration diagrams corresponding to Examples 1 to 4, respectively.

Claims

[Claims]

(1) A zoom system that consists of a front group with positive refractive power and a rear group with negative refractive power in order from the object side, and changes the focal length of the entire system by changing the distance between the front group and the rear group. A zoom lens, wherein each of the front group and the rear group is composed of two lenses and each has at least one aspherical surface.

(2) A zoom lens according to claim 1, wherein at least one of the aspherical surfaces in the front group satisfies the following conditional expression: When the maximum effective diameter of the aspherical surface is y_m_a_x , 0.
7y_m_a_x<y<1.0y_m_a_x
)-x_0(y)}≦0 where, ψ_1: Refractive power of the front group N: Refractive index of the aspherical object-side medium N': Refractive index of the aspherical image-side medium x(y): Refractive index of the aspherical surface Surface shape x_0(y): Reference spherical shape of aspheric surface However, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ r: Reference radius of curvature ε of aspheric surface: Quadratic surface parameter Ai : Aspheric coefficient ■: Paraxial radius of curvature of aspheric surface (1/■=1/r+2A_2).

(3) A zoom lens according to claim 1, wherein at least one of the aspherical surfaces in the rear group satisfies the following conditional expression: When the maximum effective diameter of the aspherical surface is y_m_a_x , 0.
For any vertical height y of the optical axis such that 8y_m_a_x<y<1.0y_m_a_x, −0.10<ψ_2・(N′−N)・d/dy{x(y
)−x_0(y)}<0 where, ψ_2: Refractive power of the rear group N: Refractive index of the aspherical object-side medium N': Refractive index of the aspherical image-side medium x(y): Refractive index of the aspherical surface Surface shape x_0(y): Reference spherical shape of aspheric surface However, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ r: Reference radius of curvature ε of aspheric surface: Quadratic surface parameter Ai : Aspheric coefficient ■: Paraxial radius of curvature of aspheric surface (1/■=1/r+2A_2).

(4) The zoom lens according to claim 1, wherein the lens constituting the front group satisfies the following conditional expression. νd_(_G_1_)<40 νd_(_G_2_)>50 However, νd_(_G_1_): Abbe number of the object-side lens forming the front group νd_(_G_2_): Abbe number of the image-side lens forming the rear group It is.