JPH0446308A - Compact zoom lens - Google Patents

Abstract

PURPOSE:To obtain the compact zoom lens by consisting the zoom lens of a front group having a negative refracting power and a rear group having a positive refracting power successively from an object side and having >=2 aspherical faces in the entire group and satisfying the special condition. CONSTITUTION:The zoom lens consists of the front group having the negative refracting power and the rear group having the positive refracting power successively from the object side. The zoom lens which changes the focal length of the entire system by changing the air spacing between the front group and the rear group is characterized by having >=2 aspherical faces in the entire system and satisfying the following condition equations: 0.65<¦phi1/phiw¦<2.0, where phi1: refracting power of the front group, phiw: the refracting power of the entire system at the wide angle end. The overall length of the zoom lens of the conventional class of 36 to 70mm focal length is shortened by 2 to 10mm if the lens has such refracting power as to satisfy the condition equation.

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. Moxibustion J (9" L technique) - Currently - 50m zoom lens for reflex camera.
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. Therefore, for example, Japanese Patent Application Laid-Open No. 58-60717, Japanese Patent Publication No. 59-Sho.
No. 13003, JP-A-61-69015, JP-A No. 61-8
No. 7117. No. 61-87118, Japanese Unexamined Patent Publication No. 1-210914, etc. have been proposed. These zoom lenses are composed of two components, negative and positive, and use two or more aspheric surfaces. However, even in these zoom lenses, it cannot be said that miniaturization and cost reduction have been sufficiently achieved. Therefore, in view of the fact that aspherical surfaces have become cheaply produced and easy to produce due to recent remarkable technological advances in plastic molding, glass molding, etc., the present invention effectively utilizes aspherical surfaces to achieve high optical performance. 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 maintains this. 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, and a distance between the front group and the rear group. A zoom lens that changes the focal length of the entire system by changing the air spacing between the lenses is characterized by having two or more aspheric surfaces in the entire system and satisfying the following conditional expression (2). 2, φ1: refractive power of the front group φ11: refractive power of the entire system at the wide-angle end. 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 and each lens. In the present invention, as long as the refractive power satisfies the above conditional expression (2), the total length can be shortened by 2 to 10 mm compared to a conventional zoom lens having a focal length of 35 to 70 mm. However, on the other hand, this worsens various aberrations, making it difficult to maintain performance with only a spherical surface. In the present invention, the refractive power of each group is strengthened and the overall length is shortened, and the deterioration of various aberrations accompanying this is suppressed by making extensive use of aspherical surfaces, thereby achieving good performance. In the present invention, by using at least two aspherical surfaces, the lens is made compact and aberrations are corrected (performance is improved). Regarding aspherical surfaces, for example, if a spherical surface is used for the lens on the object side of the rear group, it will be effective in correcting spherical aberration, and if an aspherical surface is used for the lens closest to the image side, it will be effective to correct spherical aberration. This is effective in correcting coma aberration in the area. On the other hand, if an aspherical surface is used for the object-side lens in the front group, it is effective in correcting distortion and field curvature 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.As a result, the cost can be reduced by reducing the number of lenses, and the total length and movement can be reduced. Compactness is achieved by reducing the volume. The above conditional expression defines the ratio of the refractive power of the entire system to the refractive power of the front group at the wide-angle end, and a configuration that satisfies the conditional expression is based on the overall lens length, the amount of movement for zooming,
This is effective for keeping the back focus and various aberrations corrected in a good balance. When the upper limit of conditional expression ■ is exceeded, the front group refractive power becomes excessive,
Even if an aspherical surface is used in the front group, it is difficult to correct various aberrations occurring in the front group, especially curvature of field and distortion. Also,
If the lower limit is exceeded, downward comatic aberration tends to occur at the periphery of the screen, and it becomes difficult to secure sufficient back focus. Furthermore, it is preferable that the following conditional expression 〇 be satisfied. 22, φ2: refractive power of the rear group. Conditional expression (2) 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 (2) 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. 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 formula (■) specifies the maximum effective diameter of the aspherical surface as Yma. When o<y<o, sy, arbitrary height y in the vertical direction of the optical axis
For, −(X(y)−Xs(y)) < 0.02−・−−
−−■Here, N: Aspherical object gI! Refractive index of the medium N': Refractive index of the image-side medium of the aspherical surface Radius ε: Quadratic surface parameter A,: Aspheric coefficient? ′: Paraxial radius of curvature of the aspheric 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 (■) indicates that the maximum effective diameter of the aspherical surface is Y. 8, for any height y in the vertical direction of the optical axis where o, sy***<y<y*sx, ・(X(y)-Xs(y))<O...・It is ■. Conditional expression (■) is as follows: When the maximum effective diameter of the aspherical surface is Y, 1, for any height y in the vertical direction of the optical axis of 0.8Y, , <y< Y, sx, ・(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 (2) is expressed as follows: When the maximum effective diameter of the aspherical surface is Yl, 8, O(y<0.7Y-ax, the height y in the vertical direction of the optical axis
For, ・ (X(y)−Xs(y)) < 0.01 ・
...■. 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 (X(y)−Xs (y)) < O...■. Condition (2) is 0.0 when the maximum effective diameter of the aspherical surface is Yl, 8. For any height y in the optical axis vertical direction where IY, ax<y<Ymsx, the following is true: (X(y) Xa(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 (0) is a condition for correcting the inclination of spherical aberration to the under side to the over side in the range of the third-order aberration region. At this time, the on-axis light passing through a far N location from the optical axis of the lens is over-corrected and may go to the over side, so in order to return this light to the under side, conditional expression 〇 is used. In the periphery where this is satisfied, 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). 22, φT: refractive power of the entire system at the telephoto end β: zoom ratio, where φ, <0 β=φ, /φ. 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 (■) is exceeded, it becomes difficult to maintain the back focus at an appropriate value (1.1 times or more the focal length at the wide-angle end) at the wide-angle end, making it difficult to secure space for placing the mirror. It becomes difficult. Moreover, if the upper limit is exceeded, the amount of movement of the front group and the rear group due to zooming becomes excessive [9, which is disadvantageous in terms of the configuration. 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. Embodiments of the compact zoom lens according to the present invention will be shown below. However, in each example, r1 to rllll indicate the radius of curvature of the surface counted from the object side, d + -d s indicates the axial surface spacing counted from the object side, and N, to N5. .about..nu.5 indicates the refractive index of each lens for 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 to 50.0 to 68.0 F T10 =
4.6~5.6~6.81 Supervisor 11ujl''l Tadauchika!
Eehe Geki RG*304.102 Valve” 1

[Flaw JL T4: ε=0.97677 Aa=-0,46960x 10-'Aa; 0.18970X 10-'As; 0.10218X 1O-T Al11=0.92120X 10-"AIt"0.9
8848X 1O-I3rs: t=o, 130
64X10A4=-0,44294X 1O-4 Ae knee 0.32517X 10-@As=-0.63065x10-" A+5=-0,74042X 10-"Al1"-0,
17854X10-” T7: t: 0.100IOX 10AJ=0.
90729X 10-'Aa"0.14917X10-'As--0.96660X10-' A+i= 0.61239X 10 width 11ht knee 0.
25320X10-12r8 : ε=0.93899 Aa:0.17872X 1O-3 Aa"0.41747X 10-' As:0.82935X 10-"A+a=-0,55230X10-' Al2=0.96840X 10-th Example 2> 36.0~50.0~68.0 FNo=4.6~5.6~6.8 r, *78.899 Valve 11 grandchild 1 T4: ε=0.10000X 10A, =- 0,2
4751X 10-' Aa8: 0.71600X 10-@As=-0.84637x10-' rs: E;
0,63349x 10-' Ae=-0.32364x 10-' A,=-0.11035x 10-7 1"a: e:80.100OOX 10AJ
=-0,67323X 1O-4 Ae=-0,76224x 1O-6 A@=-0,18025x 10-@rt: ε =O,100OOX 10Aa"
0.74134X 10-' Ae=-0.80597x 10-" Aa=0.94950x 10-' r8: ε:0゜100OOX 10At-0,13
887X 1O-3 As =-0,21954X 10-'Ae=0.55
614X 1 leaf 8 <Example 3>f"36.0~50.0""-68, OFNo=4.6
"5.2~5.6da4.4υU ram 73.585 Valve" mouth [Ho JL r4: ε=0.97677 A4=-0,31833X10-' Aa=o, 11552X10-6 A@"-0,38684X10- 'A+@=0.23753X 10-" rs: e=0.11687X 10Aa=-
0,26050X10-' As knee 0.73075 X 10-"As=-0,2
1403X10-'A+s"0.11257X10-" r7: ε:0.10098X10A, =0.95
703x10-' Aa=0.112f32X 10-' As=-0,82765X 1O-8 A+@knee 0.31146X10-"'Al2=-0,
21000X10-+3re: 8”0.94
743 Aa = 0.15530 .0~50.0~68.0 Fso=4.8
~5.6~6.8ra 22.506 d33.955 N2 r@Umbrella 132.522 Valve] Mouth 1 r2: ε=o, 14772X101.76500 ν2 46.25 A, =-0,19835X 10-' Ae=-0.86077X 10-" A, =-0,91491X 10-" rs: g=o, 12911X10A4=-0,
19849X 10-' Ae=0.59001X 1O-7 A*=-0,14707X 10 to 8 ry: e =0.100OOX 10A4=0
．． 98005X 1O-6 Aa knee 0.37611X 10-' Aa=-0,19401X 10-' r8: ε=O, 100OOX i. Aa=0.66420×10-'As=~0.35319X10As"J,11571X10-"<Example5> f=36.0~50.0~68.0 Fso=4.6
~5.6~6.8r++*-65,187 Valve! fL section JL rl: ε=0.92540 Aa=-0,12025x 10~4 Ae=0.52533X 10-' Ae=-0,32581X 1O-111r2:
t=0.100OOX 10A4=-0,1446
8X 10-' Ag=0.87723X 1O-7 As: 0.78426X 1O-9 r3: ε: 0゜33160 A, = -0,11960X 10-' Aa=0.14748X 1O-6 h:o, 80246X 1O-9 r4: ε=0.95585 624.151 A filter=-0,51352X 10-' Aa: 0.13347X 10-" As knee 0.13437X 10-" rs: ε=0.12368X 10A4=-0 ,2
2771X 10-'As" 0.36746X 1O-7 As knee 0.12825
0.30913X 10-' Aa=0.45464X 1O-7 As; 0.68843X10-' r7: ε=0.26965X 10At: 0.15
885X 10-” As=-0, 54318
799X, 1O-3 A@=0.32779X 10zuA@"0.57687X 10-"<Example6> A,=-0,11854X 10-' Aa=0.53054X 10-' As=-0. 14796x 10-'A+s; 0.12514X 10-" Al+2=-0,51061X 10 bow 3rs:
ε=0.100OOX 10A,=-0,11644
X 10-' Aa=0.82535X 1O-7 Aa=-0,16456x 1 leaf e A+@=O, l5146X 1 leaf II A+2=-0,61958X 10-"r7: ε
=O, 100OOX 10A, =-0,22564X
10-' Ae = 0.28631
．． 18334X 10~4 A++ =-0,55751X 10-”f =36.
0-50.0-68. OFN0=4. ．． 6～5.2～
5.6 Tenrenjisu i” LL side, LL tajiri vine ヱ” 21
Number r+m -16,275 Valve JLiL HoJL r2: ε=0.10000X10AI=-0,
15505X 10-' Aa=0.83879X 1O-7 As"-0,24127X 10-"Als:0.23757X 10"'1A12=-0,
80847X 10 3r= : e :O, 10
0OOX 10As"0.18495X 10"" Aj@=o, 20056X 10-" Al2=o, 25087X 10-" rs: E; 0.100OOX 10A4=-
0,13083X 10-' As knee 0.31645X10-8 As=0.63373X 10-' A+i”-0,10362X10-I+A+2=-0,
26952X103 <Example 7>f""28.8~44.3~68. OFNo=4. f3
~5.2~5.634.345 r7 umbrella -85,568 da 3.017 r+@ -17,384 Valve'1
．． 58892X 10" As: 0.48505X 10-,' b=-0.38701X 10-'A+s;0.65002X10-" A+2=-0, 22233X10-" r2: ε=O, 100OOX 10Aa =-0,
94516x 10-'Aa: 0.39885x 10
-” As”0.21510X10-” A+s knee 0.12936X 10-th A+z=-0,
13875X10-” ra: ε=O, 100OOX 10AJ=-0
, 78692
=0.100OOX 10Aa=J, 21705X 1
0-' Ae=-0,83224X 10-" A*Connie, 11419X 10-@ A+e knee 0.56839X10-12AI2=0.8
6732 35263X 10-”re: e:0.100OOX 10Aa=0
．． 19211X 10-'Aa;-0.35547X 1O-7 A, =-0,75079x 101 Aui=0.23221X10-''A+ 2=0.
60653X 10-heavy 3re: ε=0,10
0OOX 10A, =-0,81788X 10-' Aa=-0.67632x 1O-7 A*=-0,10159X 10-@ A+@=0.42857X 10-"Al1"0.23794X10-"<Example 8〉 f = 39.0 ~ 55.1 ~ 78.0 F so =
4.B ~5.2~5.6 Chiren Hiro LJLL side”1
Benichika Tsune Emata 41r+a -26°792 Valve JJL Section 1; rl: ε=0.100OOX 10Aa=-0,1
7314 x 10-' Aa knee 0.11099
, 23880
34891X 10-” ra: ε”O, 100OOX 10A, =-0
,25119X 10-' Ae=0.34222X 1O-7 As=-0,67319X 10-' All! =0.37125X 10-”A+2=-0,
20868X 10-”r5: ε=O, 100OO
X 10A, = 0.20886
=O, 100OOX 10An=-0,22551X
10-' As: 0.22428X 1O-7 A@=0.46396X 10-" A+s=0.61312X 10-th Al2=0.56137X 10-" rs: g=0.10000X10Aa:0.2
4322X 10-' Aa=0.10926X 10-'As"0.11323X10-" A+@: 0.15914X 10-' Day A+2=0.1
4505X 10-"rs: ε=O, 100OOX 10Aa"-0
, 31514X 10-' As knee 0.79866X10-7 A@"0.86102X 10-' A+s: 0.29418X 10-th A, = 0.83021 29980x 101 Ali: 0.26751X10-” Al2=0.23205X10 2 173: t =O, 1,0OOOX IOA, =
-0,68916x10-' Aa =0.12267 X 10-'A*=O, l6
135X 10-' A+s=0.12588X 10-" Al2=0.72978X 10-" ra: ε=0.10000X10A,=-0.
63114X 10-' A6=-0.87244X 1O-7 A*=0.14728X10-' A+@”0.20899X October I A2 Knee 0.17228X10-13rs:
ε: 0.100OOX 10A, = -0,18890X
1O-6 A6"0.19098X 10-"Al2"0.70709X 10-14 <Example 9>f"36.0-49.5-68. OFNO=4.6~5
．． 2~5.6 Emperor'' 111-JU old 14th year! Eyugo 1
1I -43,231 Valve J1 [IL r+: t = 0.10000X 10A i = 0
．． 20109X10-4 As-0, 13635X 10-' As=0.11051X 10-" A+l!=0.43942X 1O-I3A+2=-0
,51481X 1O-I3r2: ε;O,1
00OOX10A@=-0,11329X10-" All1=0.93460X 10th A12=o, 4
1743X10 bow 3 ra: t: =0.10000X 10Aa”
0.24647X 10-' A6: 0.12879X 10-6 As=0.45128X 1O-1I A+5=-0,11513X10-" Al2=〇, 56075X 1O-I3r7: ε=
O, 100OOX 10A, = 0.16088X 10
-I AI! = -0,13611 Ae”0.19383 It is a lens configuration diagram that
The arrows in the figure schematically indicate the movement of the front group and the rear group from the widest angle end (S) to the stationary far end (L). 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 fJ2 lens and both surfaces of the third and fourth lenses are aspherical. In Example 4, the image-side surface of the second lun, ! ! The object-side surface of the I3 lens and both surfaces of the fourth lens are aspherical. 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 fourth lens and a fifth lens that is 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. In Example 8, from the object side to the image side, there is 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. 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 second lens, the image side surface of the second lens, and the third lens
The object-side surface of the lens, both surfaces of the fourth lens, and the object-side surface of the fifth lens are aspherical. Embodiment 9 includes a front group consisting of a tJ2 lens consisting of a negative meniscus lens concave to the image side, a tJ2 lens consisting of a positive meniscus lens convex to the image side, a 9-biconvex positive third lens, and an object in order from the object side. and a rear group consisting of a fourth lens consisting of a negative meniscus lens with a concave side. In Example 9, both surfaces of all lenses are aspherical. 10 to 18rM 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 solid line (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 1 correspond to Examples 1 to 9, respectively, and represent the conditional expressions in the aspherical surface with (I) for the value of y, and the conditional expressions in the conditional expressions is expressed as (n). Table 2 (Values for conditional expression ■■ of each example) Table 1 (Values for conditional expression ■■ of each example) Table 3 (Example 1) Table 4 (Part 1) (Example 2) Table 5 (Example 3) Table 4 (Part 2) (Example 2) Table 6 (Example 4) Table 7 (Part 1) (Example 5) Table 8 (Part 1) (Example 6) Table 7 (Part 2) (Example 5) Table 8 (Part 2) (Example 6) Table 9 (Part 1) (Example 7) Table 10 (Part 1) (Example 8) Table 9 (Part 2) (Example 7) Table 10 (Part 2) (Example 8) Table 11 (Part 1) (Example date) 111 of "Oshi" L As explained above, according to the present invention For example, 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 the drawing]

1, 2, 3, 4, 5, 6, 7, 8, and 9 are examples of embodiment 1 of the present invention, respectively.
9 is a lens configuration diagram corresponding to FIG. Figure 10, Figure 11, Figure 12, Figure 13, Figure 14,
FIG. 15, FIG. 16, FIG. 17, and FIG. 18 are aberration diagrams corresponding to Examples 1 to 9 of the present invention, respectively. Applicant Minolta Camera Co., Ltd.

Claims (3)

[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, which has two or more aspherical surfaces in its entire system and satisfies the following conditions: 0.65<|φ_1/φ_W|<2.0 Here φ_1: refractive power of the front group; φ_W: refractive power of the entire system at the wide-angle end. (2) The front group consists of two lenses, and the rear group consists of three lenses.
The zoom lens according to claim 1, characterized in that the zoom lens comprises two lenses. (3) The zoom lens according to claim 1, wherein the front group and the rear group each include two lenses.