JPH0446310A - Compact zoom lens - Google Patents

Abstract

PURPOSE:To obtain the compact zoom lens by providing >=3 aspherical faces in a front system. CONSTITUTION:The zoom lens which consists of the front group having a negative refracting power and a rear group having a positive refracting power, successively from an object side and changes the focal length of the entire system by changing the air spacing between the front group and the rear group has >=3 aspherical faces in the entire system. There is an effect of correcting spherical aberrations when the aspherical face is used for the lens on the extreme object side in the rear group. There is an effect of correcting comatic aberrations in the peripheral part of the image plane when the aspherical face is desired to be formed on the lens of the extreme image side. On the other hand, there is an effect of correcting the distortion aberrations and curvature of field near the wide angle and when the aspherical face is used for the lens on the extreme object side in the front group. The refracting power of the respective group and respective lenses in intensified while the performance is maintained by effectively using the multiple aspherical faces in such a manner. Consequently, the number of lens element is decreased and the overall length and moving quantity are shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compact zoom lens, and more particularly to a zoom lens used in a single-lens reflex camera or the like.

Currently, the zoom lens for eye reflex cameras is 50m.
Lenses with a zoom ratio of about 2x have become mainstream in place of M lenses. Therefore, in order to make an eye reflex camera more compact and lower in cost, it is desired that this type of lens be made more compact and lower in cost. In order to make the lens system more compact, including the amount of lens movement during zooming, it is necessary to increase the refractive power of each lens group.
It can be said that increasing the number of lenses is the way to increase the refractive power while maintaining performance. On the other hand, in order to reduce costs, it is effective to reduce the number of lenses. In this way, there are many conflicting elements involved in making a lens system more compact and lowering its cost.

Note that, for example, Japanese Patent Application Laid-open No. 183613/1986 is an example of a device aiming only at compactness. Japanese Patent Publication No. 1836-1983
In the zoom lens proposed in No. 13, a fixed third lens group is provided behind the two movable negative and positive components.
Three or more aspheric surfaces are used.

However, since this zoom lens is composed of three lens groups, it cannot be said that cost reduction has been achieved.

Therefore, in view of the fact that aspherical surfaces have become cheaper to produce and more durable due to recent remarkable technological advances in plastic molding, glass molding, etc., the present invention effectively utilizes aspherical surfaces to maintain high optical performance. However, it is an object of the present invention to provide a compact zoom lens that has a small number of lenses, is low in cost, and is compact.

In order to achieve the above object, the zoom lens of the present invention consists of a front group having a negative refractive power and a rear group having a positive refractive power in order from the object side. A zoom lens that changes the focal length of the entire system by changing the air spacing is characterized by having three or more aspheric surfaces in the entire system.

As mentioned above, cost reduction (
In order to achieve compactness (reduction in the number of lenses) and compactness (reduction in the amount of movement and overall length), it is effective to increase the refractive power of each group. However, this worsens various aberrations,
This will lead to a decrease in performance.

Such a decrease in performance can be suppressed by using many aspheric surfaces, and in the present invention, by using three or more aspheric surfaces in the entire system as described above,
This makes it possible to maintain performance while making the lens more compact and lower in cost. For example, if an aspherical surface is used for the object-side lens in the rear group, it is effective in correcting spherical aberration, and if an aspherical surface is used for the most image-side lens,
This is effective in correcting coma aberration at the periphery of the screen. On the other hand, if the front group center weight also uses an aspheric surface for the object side lens,
This is effective in correcting distortion aberration and curvature of field near the wide-angle end. In this way, by effectively using many aspherical surfaces, it is possible to strengthen the refractive power of each group and each lens while maintaining performance, resulting in a reduction in the number of lenses and the overall length and travel distance. is possible.

The front group may consist of two lenses, the rear group may consist of three lenses, or both the front group and the rear group may consist of two lenses.

It is desirable that all the aspheric surfaces in the front group satisfy the following conditional expression (2).

Conditional expression (■) is, when the maximum effective diameter of the aspherical surface is Ysax, o<y<0.8Y, and the arbitrary optical axis vertical height y of sx.
For, ・(X(y)-X@(y)) < 0.02...
...■Here, φI: 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): Surface shape of the aspherical surface Xs (y) : Reference spherical shape of the aspherical surface, however, +ΣA+y≧2 r: Reference radius of curvature of the aspherical surface ε: Quadratic surface parameter A, secondary aspherical coefficient 7: Paraxial radius of curvature of the aspherical surface.

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. Furthermore, when the lower limit is exceeded, negative distortion becomes large from the intermediate focal length region to the telephoto end, and in addition, the negative shift tendency of the field curvature becomes significant in the entire zoom range.

When a lens having both surfaces aspherical is used in the front group, it is desirable that one surface satisfies the following conditional expression (2) and the other surface satisfies the following conditional expression (2).

Conditional formula (2) is, when the maximum effective diameter of the aspherical surface is Yaax, 0.8Y, , < y < Y, , For any height y in the direction perpendicular to the optical axis of x, ・(X(y) −Xs(y)) < O・・・・・・■
It is.

Conditional expression 〇 is, when the maximum effective diameter of the aspherical surface is YIIIm, for any height y in the vertical direction of the optical axis where 0.8Ymax<y<Ymaw, ・(X(y)−Xs(y)) <0.10...
...■.

In the front group, an aspherical surface that satisfies condition (2) means that the negative refractive power is weak (the positive refractive power is strong) at the periphery. This corrects distortion near the wide-angle end. Furthermore, at this time, by using an aspheric surface that satisfies conditional expression (2), the curvature of field is favorably corrected.

It is desirable that all aspheric surfaces in the rear group satisfy the following conditional expression (2).

Conditional expression (■) is expressed as 10・03〈φ・−(N '-N)-d.

-(X(y)-Xs(y)) < 0.01---
...-■ Here, φ2: Refractive power of the rear group.

If the upper limit of conditional expression (2) 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. Moreover, when the lower limit is exceeded, the spherical aberration correction effect on the annular beam becomes excessive, making it difficult to correct other various aberrations and spherical aberration in a well-balanced manner. In this case, spherical aberration tends to take a wavy shape.

When a lens having aspherical surfaces on both surfaces is used in the rear group, it is desirable that one surface satisfies the following conditional expression (2) and the other surface satisfies the following conditional expression (2).

Conditional expression 〇 is expressed as follows: When the maximum effective diameter of the aspherical surface is Ylla, for any height y in the vertical direction of the optical axis of 0゜7Y, A<y<Y□, ・ (X(y) -Xs(y)) < O...
・It is ■.

Conditional expression 〇 indicates the maximum effective diameter of the aspherical surface as y. When r,
For any optical axis vertical height y where 0.7Ymax<y<Y□8, Okuφ2・(N'-N)・□y・(X(y)-Xi(y))<0 .04...
...■.

In the rear group, an aspherical surface that satisfies conditional expression (0) means that the positive refractive power will be weak (the negative refractive power will be strong) at the periphery. Furthermore, conditional expression (2) is a condition for correcting the inclination of spherical aberration to the under side to the over side within the range of the third-order aberration region. At this time, axial light that passes through a place far from the optical axis of the lens may be overcorrected and go to the over side, so in order to return this light to the under side, it is necessary to satisfy conditional expression 〇. In the periphery, an aspheric surface that has a strong positive refractive power (a weak negative refractive power) can be introduced on the other surface.

Further, it is preferable that the amount of deviation of the aspherical surface on the side satisfying conditional expression (2) from the reference spherical surface is larger than the amount of deviation from the reference spherical surface of the aspherical surface on the side satisfying conditional expression (2).

It is desirable that the front group and the rear group be constructed so as to satisfy the following conditional expressions (1) and (2).

At 32, φiI: Refractive power of the entire system at the wide-angle end φT: Refractive power of the entire system at the telephoto end β: Zoom ratio However, φ1〈0 β = φ−/φT It is.

These are conditions for keeping the overall length of the lens, the amount of movement for zooming, the back focus, and the state of correction of various aberrations in a good balance.

When the lower limit of conditional expression (■) is exceeded, the Petzval sum will take a large negative value, the image plane will tilt significantly in the positive direction, and the distortion at the wide-angle end will take a large positive value. . Furthermore, when the upper limit is exceeded, it is necessary to increase the distance between the front and rear groups during zooming, and the distance between the front and rear groups becomes large at the wide-angle end, resulting in an increase in the overall length of the lens.

If the lower limit of conditional expression 〇 is exceeded, it becomes difficult to maintain the back focus at an appropriate value (1.1 times or more of the focal length at the wide-angle end) at the wide-angle end, making it difficult to secure space for arranging the mirror. It becomes difficult. In addition, if the upper limit is exceeded, the amount of movement of the front and rear groups during zooming will be excessive, which will be disadvantageous in terms of lens barrel construction.The following conditional expression 〇, [phase] must also be satisfied when determining the overall length of the lens.

This is effective for maintaining a good balance between the amount of movement for zooming, the back focus, and the state of correction of various aberrations.

However, φ1〈0 It is.

Conditional expression (2) defines the ratio between the refractive power of the entire system and the refractive power of the front group at the wide-angle end. When the upper limit of conditional expression (0) is exceeded, the front group refractive power becomes excessive, and even if an aspherical surface is used in the front group, it becomes difficult to correct various aberrations occurring in the front group, especially curvature of field and distortion aberration. Furthermore, when the lower limit is exceeded, there is a marked tendency for downward coma aberration to occur at the periphery of the screen, and it becomes difficult to secure sufficient back focus.

The conditional expression [phase] defines the ratio between the refractive power of the entire system and the refractive power of the rear group at the wide-angle end. When the upper limit of conditional expression [phase] is exceeded, the rear group refractive power becomes excessive, and even if an aspherical surface is used in the rear group, it becomes difficult to correct various aberrations occurring in the rear group, especially spherical aberration. Furthermore, when the lower limit is exceeded, there is a marked tendency for downward coma aberration to occur at the periphery of the screen.

Even if a lens system with almost no refractive power is added in front of the front group, behind the rear group, or between the front group and the rear group of the zoom lens according to the present invention, this does not depart from the spirit of the present invention.

The additional lens system is preferably one in which the absolute value of the refractive power is one-third or less of the refractive power of the entire system at the telephoto end.

1 Example - Hereinafter, an example of a compact zoom lens according to the present invention will be shown.

However, in each embodiment, r, ~r+a represent the radius of curvature of the surface as counted from the object side, d1~d represent the axial spacing as counted from the object side, and N1~N6. C1 to C5 indicate the refractive index and Atsube number of each lens with respect to the d-line counted from the object side.

Further, f indicates the focal length of the entire system, and FNO indicates the open F number.

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)).

<Example 1>f"36.0~50.0~68.OFNO=4.6~5
．． 6 to 6.8rs*304.102 Valve li yo l L r4 : ε=0.97677 A,=-0,46960X 10-' Aa=0.18970X 10-6 As=-0,10218X 10-'A+s;0 .92120X 10-” Al1”0.98648X10-” rs: g =0.13064X 10A4=-
0,44294X10-' M = -0,32517X10-' A reference = -0.63065X 1O-9 A,. =-0,74042X10"I'A+e=-0,
17854X10-” r7: g =0.100IOX 10A4:0.
90729X10-'A6=-0,14917X10-' Am knee 0.98660X10-"A+5=-0,61239X10-" A+2=-0,25320X 1O-12r8: ε
=0.93899 A4=o, 17872X 10-" Aa=0.41747X 10-' As=0.82935X 10-" A+ @"-0,55230X10-'AI2"0.9
6840X10-"<Example2> f=36.0-50.0-68.0 r*I 78.899 Valve 11 [ra: t: 0.100OOX10Aa"-0
, 24751
, 63349
0,67323
134x 10-' ^a knee 0.80597X10'''6 As=0.94950x 10-" r@: ε=0.10000x10 A4=0.13887X 10-" Aa=-0,21954X 10-" As= 0.55614X 10-” <Example 3> f”36. O~50.0~88. OFNO=4.6~5
．． 2~5.6r6 13,535 rll 73.585 Valve ITL JL ra: ε=0.97677 A,=-0.31833X 10-' Aa=0.11552X 10-' As=-0.38664X 1O- 8 A++=0.23753X 1O-1er5: ε=
0.11687X 10Aa=-0,26050x 1
0-'As=-0.73075X10-' A++As knee 0.73075X10-'A++ knee 1257X 10-" r7: ε:0.10098X10A4=0.95
703x 1O-a Ae=0.11262X 10-” da 22.944~12.029~4.600rs
Rate As"-0,82765X 10-" ^+s knee 0.31146X 10-"Al1"-0,
21,000 - Mouth <Example 4> f = se, o~so, o~ss, o F 5o=4
．． 6 ~ 5.6 ~ 6.8132.522 Tip J■ [FukilL r2: ε=0.14772X 10A4 Knee 0
．． 19835
0,19849X 10-' As = 0.59001X 10-' As knee 0.14707
98005X 1O-6 Aa=-0,37611X10-' As knee 0.19401X10-@r8: ε=0.100OOX 10A4:0.68
420X 10-'Aa=-0,35319X10-" As2-0.11571X 10-"<Example5> f=36.0-50.0-68. OFNO=4.6~5
．． 6-6.8 Emperor'ji1 [juJ■wa1 Milk vine Eyukirrg* 65.1.87 Ni'11 stop Cr: ε=0.92540 A,=-0,12025X 10-' Aa=0.52533x 1O-7 As=-0,32581X 1O-111r2:
ε: 0.1oooox 10At; -0,14468
X10-'Aa"0.87723X 1O-7 As=0.78426X 10-' ra: e ;0.331F30A, =-0,1
1960X10-' Aa=0.14748X 10-' As=0.80248X 10-' r4: ε=0.95585 Aj=-0,51352X 10-' Aa:0.13347X 10-' A@knee 0.13437X 10 -” r6: E =0.12368X 10A, =~
0.22771X 10-' As: 0.38746X 1O-7 A, = -0,12825X 10-' r6: ε=-0,13009X 10A4=0.3
0913X 10-'Aa"0.45464X10" Ae=-0,68843X 10-" rr: 5 =0.26985X 10Aa=0
．． 15665x10-"As"-0,54318X10-' As knee 0.17532X 10-" rs: ε=-0,21970 A4=0.19799X 10-" Aa: 0.32779X10-' As knee 0.57687X10-'<Example6> f=36.0~50,0~68.0 11 1juJ00 [FNO=4.6~5.2~5.6 Ku JL! Zj number rls -16,275 1m1L r2: ε=0.10000X 10A,=-0,1
5505x10-' A@=0.83879X 10-' Aa=-0.24127X 10-" A+s=0.23757X 10-" A through 2 knees 0.80847X 1O-13ra:
e = O, 100OOX 10A4”J, 11854
X 10-' Ae = 0.53054X 10-F As = -o, 14796X 10-@ A1゜ = 0.12514
"-0,11644X 10-' Aa=0.82535X 1O-7 Ae;-0,16456X10-@A+s=0.15148X10-"Al2=-0,61958X10-" r7: ε=O,100OOX 10At=-0 ,2
2564x 10-' As=0.28631X 1O-7 A*"0.40710X 10-'A1g=0.94855X10-" Al2=0.43296X 10 3 r8: ε=o, 1ooooox i.

An"0.18334X 10-' As=-0.55751X 10-'A@"0.18495X10-" AI self=0.20056X 10-' self A+a=0.2
5087X 10-” rll: ε:0.10000×10A, =-0,1
3083X 10-' Ae knee 0.31645X 10-' A*=0.63373X 10-' A,. =-Q, 10362 X 10th A+t=-
0,26952X October 3 <Example 7> f=28.8~44.3~88.0 Fso=4.6
~5.2~5.6da 5.668 rls -17,384 Valve IJL arc 1 rl: ε:0,100OOX 10A4=0.
58892x 1O-6 Ae=0.48505x 1O-7 A*=-0,38701X 10-' A+s”0.65002X 1O-12A12=-0,
22233X 10 5r2: e = O, 100
OOX 10Aa=-0,94518X 1O-5 Ae=0.39865X 1O-7 Aa=-0,21510X10-"A+i+=-0,12936X10-"Al2"-0,
13875X 10~13ra: 5:0.1
00OOX 10A, =-0,78f392X 1O-
6Aa = -0,22629X10-" Ag=-0,77105X 10-" A+s:0.41977X 10th A+a=-0,84804X 1 leaf 14r,: e
=O, 1oooox10A, =-0.21705X 1
0-'As"J,83224X10-" A@=-0,11419X 10-" A1 meeting=-0,56839X 10- + 2A+2:
0.88732X 1O-I4rγ: ε=0.10
0OOX 10A4=-0,97076x 10-' Ae=-0,46160x 10-? A*=0.2s689x10-'A+s;-0,15883X10-" A1=0.35263X 1 leaf l4 r8: ε=O,100OOX10 At:o, 19211X10~4 As"-0,35547X 10-" Aa= -0,75079
7314X 10-' Ae knee 0.11099
6533X 10-" r2: ε: 0.10000X10A, = -0,
23680X10-' A6=-0.15564X 10-'As"-0,11770X10-"A+i"0.89290X10-" A+2=0.34891X 1O-13r4: ε=
O,100OOX 10A4=-0,25119x10
-' As =0.34.222 x 1 leaf 7As"-0,8
7319X 10-'A+s" 0.37125X 10-■ A+2=-0,20888
1788X10-' As knee 0.67632X10-'As--0,10159X10-" A1・=0.42857X 1O-12A+2=0.2
3794X10-+4 <Example 8> f=39.0~55.1=78.0 Fso=4.8
~5.2~5.61 Natsume 1] Roj mouth L” Stable near! LL
Beho r+e -26,792 A,=0.20886x10-6 Ae=0.65790X10-7 A@any, 64905 X 10-"A+g=0.
65032
2551X 1O-J Aa=0.22428x10-' A8: 0゜48396X10-" A++=0.61312X 10-" A12=o, 56137X10-" ra: ε =o, 1oooox 10A, =0
．． 24322X10-'Aa"0.10926X 1 leaf 6 Aa"0.11323X10-'A+e:0.15914X10-" A+2=0.14505X 1O-12rQ:
ε”O, 100OOX 10A4=-0,3I5I4X
10-5 Ae=-0,79866x 10-'ls"o, 86102X 10-' A+s=0.29418X 10-" A+g=0.70709X 10-14 <Example date> f=36.0-49.5 ~68. OFNO=4.6~5
．． 2~5.6rl: t: =O, 100OOX
10A, = 0.20109X 10" As = 0.13635X 10-' As = 0.11051X 10-' A10 = 0.431342X 10-13AI2"-0
,51481X10-"r2: t=O,100OOX10A4=0.8
3021X 1O-6 Ae"0.33585X 10-' A*=0.29980X 10-" AtI=0.26751X 10-"Al1"0.23205X10-" r3: ε=O, 100OOX 10Aa"-0,6
8916X10-' Ae=-0.12267X 10-' As=0.16135X 10-"Al1"0.12568X10-"A+z=0.72978X10-" ra: g:o, 10000X10A4;-0,
63114X 10-'As=-0.87244X10-'As"0.14728X10-'A+i:0.20899X10-" A+2=-0,17228X 10-"r5: ε=
O,100OOX 10Aa=-0,16890x 1
0-' Aa: 0.19098X 10-" As knee 0.11329X10-" A+ *=0.93460 X 10-mouth A+2=0.
41,743 56075X 10-” rt: t=O, 100OOX 10A4=0
．． 16088X 10-' As knee 0.13611
29101X102 r++: t=O, 100OO×10A4=0
．． 52549X 10" As: 0.19383X 1 leaf 6 Aa; -0,91899X 1O-Q A+a knee 0.43772X 10-th A+2=0.1
0395 The movement toward (L) is schematically shown.

Examples 1, 2, and 4 all have a front group consisting of, in order from the object side, a first lens consisting of a negative meniscus lens concave toward the image side and a second lens consisting of a positive meniscus lens convex toward the object side; It is composed of a rear group consisting of a positive third lens and a biconcave negative fourth lens. In Example 1, the image-side surface of the second lens, the object-side surface of the third lens, and both surfaces of the fourth lens are aspherical surfaces. In Example 2, the image side surface of the second lens, the third lens and the fourth lens
Both surfaces of the lens are aspheric. In Example 4, the image-side surface of the third lens, the object-side surface of the third lens, and both surfaces of the fourth lens are aspherical surfaces.

Embodiment 3 includes a front group consisting of, in order from the object side, a first lens consisting of a negative meniscus lens concave toward the image side and a second lens consisting of a positive meniscus lens convex toward the object side, and a positive third lens having nine biconvex sides. It consists of a rear group consisting of a biconcave negative fourth lens and a fifth lens consisting of a positive meniscus lens convex toward the object side. In Example 3, the image-side surface of the second lens, the object-side surface of the third lens, and both surfaces of the fourth lens are aspherical surfaces.

Embodiment 5 includes, in order from the object side, a first lens consisting of a negative meniscus lens concave to the image side, a front group consisting of a biconvex positive second lens, a biconvex positive third lens, and a concave lens concave to the object side. and a rear group consisting of a fourth lens consisting of a negative meniscus lens.

In Example 5, both surfaces of all lenses are aspherical.

Embodiment 6 has a front group consisting of a biconcave negative first lens and a biconvex positive second lens in order from the object side.

It is composed of a rear group consisting of a biconvex positive third lens, a biconcave negative fourth lens, and a fifth lens consisting of a positive meniscus lens convex to the image side. In Example 6, the image-side surface of the second lens, the image-side surface of the second lens, the object-side surface of the third lens, both surfaces of the fourth lens, and the object-side surface of the fifth lens are aspherical. It is.

Embodiment 7 includes a front group consisting of, in order from the object side, a first lens consisting of a negative meniscus lens that is concave toward the image side and a second lens consisting of a positive meniscus lens convex toward the object side, and a third lens that is biconvex positive. It consists of a rear group consisting of a biconcave negative fourth lens and a fifth lens consisting of a positive meniscus lens convex to the image side. In Example 7, both surfaces of the second lens, the image-side surface of the second lens, the object-side surface of the third lens, both surfaces of the fourth lens, and the object-side surface of the fifth lens are aspherical.

Embodiment 8 has a front group consisting of a concave negative meniscus lens, a biconvex positive second lens, a biconvex positive third lens, and a biconcave negative lens in order from the object side to the image side. It consists of a rear group consisting of a fourth lens and a fifth lens consisting of a positive meniscus lens convex to the image side. In Example 8, both surfaces of the first lens, fI! The image side surface of the j2 lens, the object side surface of the third lens, both surfaces of the fourth lens, and the object side surface of the fifth lens are aspheric surfaces.

Embodiment 9 has a front group consisting of, in order from the object side, a negative meniscus lens that is concave toward the image side and a second lens that is a positive meniscus lens that is convex toward the image side, and a positive third lens that is seven-convex.
Consists of a negative meniscus lens that is concave on the object side!
It consists of a rear group consisting of 14 lenses. In Example 9, both surfaces of all lenses are aspherical.

10 to 18 are aberration diagrams corresponding to Examples 1 to 9, in which (S) indicates the focal length at the wide-angle end.

(M) shows the aberration at the intermediate focal length, and (L) shows the aberration at the telephoto end focal length. Further, the solid line (d) represents the aberration with respect to the d-line, and the dotted line (SC) represents the sine condition. Further, the dotted line (DM) and the real Jl (DS) represent astigmatism on the meridional plane and the sagittal plane, respectively.

Table 1 shows the values of conditional expression (2) in Examples 1 to 9, respectively.

Table 2 shows each of the conditional expressions 〇 in Examples 1 to 9.

Tables 3 to 11 correspond to Examples 1 to 9, respectively.
Conditional expression (■■■) for each aspherical surface for the value of y is represented by (I), and conditional expression (■■■) is represented by (II).

Table 1 (Values for conditional expression ■■ of each example) Table 3 (Example 1) Table 2 (Values for conditional expression 〇 [phase] of each example) Table 4 (Part 1) (Example 2) Table 4 (Part 2) (Example 2) Table 6 (Example 4) Table 5 (Example 3) Table 7 (Part 1) (Example 5) Table 7 (Part 2) ( Example 5) Table 8 (Part 2) (Example 6) Table 8 (Part 1) (Example 6) Table 9 (Part 1) (Example 7) Table 9 (Part 2) (Example 7) Table 10 (Part 2) (Example 8) Table 10 (Part 1) (Example 8) Table 11 (Part 1) (Example 9) Table 11 (Part 2) (Example 9) As explained above, according to the present invention, it is possible to realize a low-cost and compact zoom lens with a small number of lenses while maintaining high optical performance. Also,
If the zoom lens according to the present invention is used in a -eye reflex camera, the camera can be made more compact and lower in cost.

[Brief explanation of drawings]

Figure 1, Figure 2, Figure 3, Figure 4, Figure 5,
FIG. 6, FIG. 7, FIG. 8, and FIG. 9 are lens configuration diagrams corresponding to Examples 1 to 9 of the present invention, respectively. Figure 10, Figure 11, Figure 12, District 13, Figure 14,
FIG. 15, FIG. 16, gJ17, and FIG. 18 are aberration diagrams corresponding to Examples 1 to 9 of the present invention, respectively. Applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] (1) Consists of a front group with negative refractive power and a rear group with positive refractive power in order from the object side, and by changing the air distance between the front group and the rear group, the focal point of the entire system is created. A zoom lens that changes distance, characterized by having three or more aspheric surfaces in the entire system.