JPH0829683A - Small zoom lens - Google Patents

Abstract

PURPOSE:To provide a small zoom lens having a short total length and composed of two lens groups having high optical performance over a whole variable power range and a power variation ratio of about 1.5-2.0 CONSTITUTION:In a small zoom lens comprising two lens groups of a first group having a positive refractive power and a second group having a positive refractive power, and varying the power by changing the interval of both lens groups, the first lens group comprises a positive first lens whose convex face confronts the object side, a second negative lens whose both faces are concave, a third positive lens whose both lens faces are convex faces, the second group comprises a fourth positive meniscus lens whose convex face confronts the image plane side and a fifth negative meniscus lens whose convex face confronts the image plane side and the focal distance of the first group f1, the focal distance of the whole system at the wide-angle end fw, the air gap D2 between the first and the second lenses, the air gap D4 between the second and the third lenses and distance from the lens face on the object side of the first lens to the lens face on the image plane side of the third lens are properly set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact zoom lens composed of two lens groups suitable for a lens shutter camera, a video camera, etc., and in particular, by properly setting the lens configuration of each lens group, aberration correction is possible. A good zoom ratio with a short back focus and a short overall lens length (distance from the first lens surface to the image plane).
The present invention relates to a compact zoom lens of about 2.0.

[0002]

2. Description of the Related Art Recently, with the downsizing of lens shutter cameras, video cameras, etc., there has been a demand for a compact zoom lens having a short overall lens length.

The applicant of the present invention has previously filed Japanese Patent Application Laid-Open No. 56-128911.
JP-A-57-201213 and JP-A-60-
-170816, JP-A-60-191216, JP-A-62-56917, etc., a first lens group having a positive refractive power and a second lens group having a negative refractive power are arranged in order from the object side.
We have proposed a so-called two-group zoom lens that is composed of one lens group and that varies the magnification by changing the distance between both lens groups.

In this publication, a positive / negative refractive power arrangement is adopted in order from the object side to provide a two-group zoom lens having high optical performance with a relatively short back focus and a shortened overall lens length. Has achieved.

Of these, in Japanese Patent Laid-Open No. 56-128911, a small zoom in which the first group is composed of four lenses, positive, negative, positive and positive, and the second group is composed of two lenses, positive and negative. I am proposing a lens.

Further, in Japanese Patent Laid-Open No. 57-201213, the first group is composed of three positive, negative and positive lenses, and the second group is composed of two lenses, positive and negative, and a zoom ratio of about 1.5. Has proposed a small zoom lens.

In addition, in JP-A-3-1270909 and JP-A-3-127010, the first group is composed of three lenses, positive, negative, and positive, and the second group is composed of two lenses, positive and negative. A two-group zoom lens having a small number of lenses, which is configured and has an aspherical surface on one lens surface, is proposed.

[0008]

In the two-group zoom lens composed of the two lens groups of the first lens group having a positive refractive power and the second lens group having a negative refractive power, the total number of lenses is set to about five. , 1.5-, while downsizing the entire lens system
In order to obtain good optical performance over the entire zoom range while having a zoom ratio of about 2.0, it is necessary to set the lens configuration of each lens group appropriately.

In the two-group zoom lens, if the refractive powers of both the first and second lens groups are increased, the amount of movement of each lens group during zooming is reduced, and the total lens length can be shortened. However, if the refracting power of each lens unit is simply increased, the aberration variation due to zooming becomes large, and it becomes difficult to satisfactorily correct this.

According to the present invention, in a so-called two-group zoom lens, the total lens length is shortened at a zoom ratio of about 1.5 to 2.0 by appropriately setting the lens configuration of each lens group. An object of the present invention is to provide a compact zoom lens having high optical performance over a double range.

[0011]

A compact zoom lens according to the present invention has two lens groups, a first lens group having a positive refractive power and a second lens group having a negative refractive power, in order from the object side. In a compact zoom lens for changing the magnification by changing the interval between the groups, the first group includes a positive first lens having a convex surface directed toward the object side, a negative second lens having both concave lens surfaces, and both lens surfaces. Has three lenses, a convex positive third lens, and the second group is a meniscus positive fourth lens having a convex surface facing the image surface side and a meniscus negative lens having a convex surface facing the image surface side. No. 5 lens, the focal length of the first group is f1, the focal length of the entire system at the wide-angle end is fw, the air gap between the first lens and the second lens is D2, and the second lens is And the air distance between the third lens and the lens surface from the object side lens surface of the first lens to the image side side of the third lens by D4. When the length to the groove surface is DL1, 0.5 <f1 / fw <0.9 (1) 0.1 <DL1 / fw <0.35 (2) 0.005 <( It is characterized by satisfying the condition of D2 + D4) / fw <0.03 (3).

[0012]

1 to 8 are lens cross-sectional views at the wide-angle end according to Numerical Embodiments 1 to 8 of the present invention. In the figure, L1 is the first lens group having a positive refractive power, and L2 is the second lens group having a negative refractive power. By decreasing the distance between both lens groups, both lens groups are moved to the object side as shown by the arrow. Zooming from the wide-angle end to the telephoto end.
SP is a stop, which is arranged on the image plane side of the first lens unit in the present invention, and moves integrally with the first lens unit upon zooming. I
P is the image plane.

In the present embodiment, by adopting such a zoom system and the lens structure as described above, the zooming is performed while shortening the overall lens length, widening the angle of view at the wide-angle end, and shortening the overall lens length. The ratio of about 1.5 to 2.0 corrects the aberration variation due to zooming, and obtains high optical performance over the entire zoom range.

Next, the features of the lens structure of the two-group zoom lens according to the present invention will be described.

In the two-group zoom lens of the present invention, the first
Since the image forming performance of the group is enlarged while being corrected by the second group, the first group is desired to have a lens configuration capable of excellently correcting aberrations. Therefore, the first group has a triplet lens, which is a single-focus lens and has a positive, negative, and positive lens, which facilitates good aberration correction, as a basic configuration.

In particular, the positive first meniscus lens having the convex surface facing the object side of the first lens group, and the second negative lens element having concave surfaces on both lens surfaces.
The lens and 3 of the positive third lens with both lens surfaces convex
By using the two lenses, mainly spherical aberration, coma aberration, chromatic aberration, etc. are favorably corrected and the assembling accuracy in the lens assembly is relaxed.

Further, in the two-group zoom lens, the second group is located close to the image plane, so that the outer diameter of the lens becomes large. For this reason, if the second lens group is configured with a large number of lenses, the size of the lens system will be increased.

Therefore, in the present invention, it is configured to have two lenses having a predetermined shape. In particular, it is mainly composed of two lenses, namely, a meniscus-shaped fourth positive lens whose convex surface faces the image side and a meniscus-negative negative fifth lens whose convex surface faces the image surface side. Off-axis aberrations such as mold distortion are well corrected. In the lens configuration of the basic configuration, the above conditional expressions (1) to (3) are satisfied.

Next, the technical meanings of the above conditional expressions will be described. Conditional expression (1) relates to the refracting power of the first lens group, and is mainly for maintaining the good optical performance and for downsizing the entire lens system. When the upper limit of conditional expression (1) is exceeded and the refractive power of the first lens unit becomes too weak (the focal length is too long), the amount of movement of the first lens unit during zooming becomes large and the lens system becomes large. On the other hand, if the refractive power of the first lens group becomes too strong below the lower limit, the total lens length will be shortened, but the amount of aberration generated from the first lens group will increase, making it difficult for the second lens group to correct it. . In addition, the amount of image shift with respect to the positional shift becomes large, which requires a highly accurate lens holding mechanism, and the holding mechanism becomes complicated, which is not preferable.

Conditional expression (2) relates to the ratio of the thickness (length in the optical axis direction) DL1 of the first lens group to the focal length of the entire system at the wide-angle end, mainly for compactness of the entire lens system while varying the magnification. This is to satisfactorily correct various aberrations. If the thickness DL1 increases beyond the upper limit of the conditional expression (2), the first group becomes large, which is not good. Further, if the thickness DL1 decreases below the lower limit value, the fluctuations of spherical aberration and coma aberration during zooming increase, and it becomes difficult to correct these in a well-balanced manner.

Conditional expression (3) is defined by the first lens of the first group and the second lens of the first group.
Regarding the ratio of the air distance D2 between the lens and the air distance D4 between the second lens and the third lens to the focal length of the entire system at the wide-angle end, fluctuation of spherical aberration during zooming is mainly suppressed, and This is for achieving compactification of the first group.

If the upper limit of conditional expression (3) is exceeded, the amount of spherical aberration generated in the first lens group at the telephoto end increases, and the two lens elements in the second lens group can correct the spherical aberration satisfactorily. It will be difficult. In particular, spherical aberration is undercorrected, which is not good. On the other hand, if the value goes below the lower limit, the setting of the lens shape for correcting various aberrations, particularly spherical aberration, is limited, which is not preferable.

In the present invention, in order to achieve further compactification of the first lens group, it is desirable to set the upper limit of conditional expression (3) to 0.02. Further, it is desirable that the lower limit value be 0.008.

The small-sized zoom lens which is the object of the present invention can be achieved by satisfying the above conditions.
Furthermore, it is preferable to satisfy at least one of the following conditions in order to obtain good optical performance while reducing the size of the entire lens system.

(1-1) When the distance from the object-side lens surface of the first lens to the image surface at the wide angle end is Lw, 0.9 <Lw / fw <1.2 (4) It is to satisfy the condition.

Conditional expression (4) relates to the ratio of the optical total length at the wide-angle end to the focal length of the entire system at the wide-angle end, mainly for achieving compactness of the entire lens system while maintaining good optical performance. It is a thing. If the optical total length at the wide-angle end increases beyond the upper limit of conditional expression (4), the rear lens diameter increases and the entire lens system becomes large, which is not good. If the optical length at the wide-angle end is reduced below the lower limit, compactness can be achieved, but the refracting power of each lens unit becomes stronger, making it difficult to correct various aberrations.

In the present invention, it is preferable to set the upper limit value of the conditional expression (4) to 1.05, because more compactness can be realized.

(1-2) The radius of curvature of the image side lens surface of the second lens is R4, the radius of curvature of the object side lens surface of the third lens is R5, and the lens thickness of the second lens is D3.
Then, the condition is 0.5 <R4 / R5 <0.9 (5) 0.035 <D3 / fw <0.08 (6).

Conditional expression (5) relates to the ratio of the radius of curvature of the image side lens surface of the negative second lens in the first group to the radius of curvature of the object side lens surface of the positive third lens, This is for appropriately setting the shape of the air lens formed by the lens and the third lens, and correcting spherical aberration favorably.

If the upper limit of conditional expression (5) is exceeded, the balance of the spherical aberration generated by the second lens and the third lens will be lost,
Spherical aberration is undercorrected. On the other hand, if the value goes below the lower limit, it becomes difficult to correct the spherical aberration generated by the second lens by the third lens, and the spherical aberration becomes overcorrected, which is not preferable.

In the present invention, it is desirable to set the upper limit of conditional expression (5) to 0.8 as the shape of the lens surface for correcting various aberrations in good balance. Further, it is desirable to set the lower limit value to 0.52.

Conditional expression (6) relates to the ratio of the thickness of the second lens of the first lens unit to the focal length of the entire system at the wide-angle end, and is mainly used to satisfactorily correct astigmatism over the entire zoom range. It is a thing. If the thickness of the second lens increases beyond the upper limit of conditional expression (6), the size of the first lens group becomes large and the cost increases, which is not preferable. If the thickness of the second lens is reduced below the lower limit, the variation of astigmatism associated with zooming increases, and it becomes difficult to maintain good optical performance over the entire zoom range.

(1-3) For the fourth lens of the second group, it is preferable to use a plastic lens having an aspherical surface whose positive refractive power becomes stronger toward the periphery of the lens. According to this, it becomes possible to satisfactorily correct spherical aberration and coma at the same time, and it is possible to achieve compactification of the second lens group and the entire lens length at a low cost without deteriorating the optical performance.

(1-4) The focal length of the fourth lens is f
When 4 is set, the condition of 0.1 <fw / f4 <0.5 (7) is satisfied.

Conditional expression (7) relates to the ratio of the focal length of the positive meniscus fourth lens of the second lens unit to the focal length of the entire system at the wide-angle end, and mainly corrects spherical aberration and coma in good balance. It is for the purpose. When the upper limit of conditional expression (7) is exceeded and the refracting power of the fourth lens becomes too strong, it becomes difficult to correct spherical aberration and coma in a well-balanced manner. If the lower limit is exceeded and the refractive power of the fourth lens becomes too weak, spherical aberration at the telephoto end becomes overcorrected, which is not good.

(1-5) When the refractive index and the Abbe number of the material of the fifth lens are N5 and ν5, respectively: 1.55 <N5 <1.73 (8) 50 <ν5 ...... ( 9) To satisfy the following condition.

The conditional expressions (8) and (9) are for properly setting the refractive index and the Abbe number of the material of the negative fifth lens, and mainly for favorably correcting the off-axis aberration and the chromatic aberration.

Exceeding the upper limit of conditional expression (8) is not preferable because it is disadvantageous in cost reduction. On the other hand, when the value goes below the lower limit, the curvature of the lens surface becomes strong in order to maintain good off-axis aberrations, which makes it difficult to set an appropriate lens shape, which is not preferable. If the conditional expression (9) is deviated, the variation in lateral chromatic aberration due to zooming becomes large.

Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air gap from the object side, and Ni and νi are respectively from the object side of the i-th lens. The refractive index of glass and the Abbe number. Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples.

In the numerical examples, the aspherical shape is such that the radius of curvature of the lens surface is R and the optical axis direction is X (the light traveling direction).
Axis, the Y axis is perpendicular to the optical axis, and B, C, D, and E are aspherical coefficients, respectively.

[0041]

[Equation 1] It is represented by the formula In addition, "e-X" is "10
^-X "means.

Numerical Example 1 F = 37.99 to 57.97 Fno = 7.20 to 11.0 2ω = 59.3 ° to 40.9 ° R 1 = 9.84 D 1 = 2.10 N 1 = 1.51633 ν 1 = 64.2 R 2 = -110.75 D 2 = 0.26 R 3 = -12.91 D 3 = 1.80 N 2 = 1.80609 ν 2 = 41.0 R 4 = 12.48 D 4 = 0.21 R 5 = 22.95 D 5 = 3.34 N 3 = 1.71999 ν 3 = 50.3 R 6 = -9.72 D 6 = 1.30 R 7 = Aperture D 7 = Variable R 8 = -19.92 D 8 = 2.00 N 4 = 1.59270 ν 4 = 35.3 R 9 = -17.55 D 9 = 4.10 R10 = -9.61 D10 = 1.15 N 5 = 1.60311 ν 5 = 60.7 R11 = -43.56

[0043]

[Table 1] Aspheric surface coefficient 8th surface: A = 0 B = 9.066 e-05 C = 5.471 e-07 D = 2.816
e-09 E = 0 <Numerical example 2> F = 37.99 to 57.95 Fno = 7.30 to 11.1 2 ω = 59.3 ° to 40.9 ° R 1 = 10.84 D 1 = 1.80 N 1 = 1.57098 ν 1 = 50.8 R 2 = -152.17 D 2 = 0.27 R 3 = -13.54 D 3 = 2.00 N 2 = 1.83400 ν 2 = 37.2 R 4 = 13.75 D 4 = 0.27 R 5 = 24.85 D 5 = 3.42 N 3 = 1.74319 ν 3 = 49.3 R 6 = -10.31 D 6 = 1.30 R 7 = Aperture D 7 = Variable R 8 = -22.60 D 8 = 2.00 N 4 = 1.58306 ν 4 = 30.2 R 9 = -16.14 D 9 = 3.16 R10 = -9.61 D10 = 1.20 N 5 = 1.71299 ν 5 = 53.8 R11 = -39.72

[0044]

[Table 2] Aspheric surface coefficient 8th surface: A = 0 B = 7.962 e-05 C = 2.953 e-07 D = 7.268
e-09 E = 0 <Numerical Example 3> F = 39.09 to 58.10 Fno = 7.20 to 107 2ω = 57.9 ° to 40.9 ° R 1 = 9.76 D 1 = 1.80 N 1 = 1.51633 ν 1 = 64.2 R 2 = -148.97 D 2 = 0.27 R 3 = -12.40 D 3 = 1.70 N 2 = 1.78589 ν 2 = 44.2 R 4 = 12.75 D 4 = 0.25 R 5 = 22.15 D 5 = 3.00 N 3 = 1.67790 ν 3 = 55.3 R 6 = -9.33 D 6 = 1.30 R 7 = Aperture D 7 = Variable R 8 = -20.22 D 8 = 2.10 N 4 = 1.58306 ν 4 = 30.2 R 9 = -17.27 D 9 = 3.11 R10 = -9.60 D10 = 1.20 N 5 = 1.60311 ν 5 = 60.7 R11 = -46.04

[0045]

[Table 3] Aspheric surface coefficient 8th surface: A = 0 B = 7.399 e-05 C = 5.616 e-07 D = 3.843
e-09 E = 0 <Numerical example 4> F = 39.07 to 58.07 Fno = 7.00 to 0.42 ω = 58.0 ° to 40.9 ° R 1 = 9.39 D 1 = 1.80 N 1 = 1.51633 ν 1 = 64.2 R 2 = -77.45 D 2 = 0.31 R 3 = -12.62 D 3 = 1.60 N 2 = 1.78589 ν 2 = 44.2 R 4 = 12.38 D 4 = 0.22 R 5 = 23.27 D 5 = 3.20 N 3 = 1.63853 ν 3 = 55.4 R 6 = -8.99 D 6 = 1.60 R 7 = Aperture D 7 = Variable R 8 = -22.58 D 8 = 1.80 N 4 = 1.58306 ν 4 = 30.2 R 9 = -17.85 D 9 = 2.81 R10 = -9.63 D10 = 1.00 N 5 = 1.60300 ν 5 = 65.5 R11 = -53.88

[0046]

[Table 4] Aspheric surface coefficient 8th surface: A = 0 B = 7.615 e-05 C = 5.676 e-07 D = 3.459
e-09 E = 0 <Numerical Example 5> F = 35.65 to 58.06 Fno = 7.00 to 11.4 2ω = 62.5 ° to 40.9 ° R 1 = 9.85 D 1 = 1.90 N 1 = 1.51633 ν 1 = 64.2 R 2 = -84.72 D 2 = 0.41 R 3 = -12.43 D 3 = 1.60 N 2 = 1.78589 ν 2 = 44.2 R 4 = 11.63 D 4 = 0.22 R 5 = 16.79 D 5 = 3.10 N 3 = 1.63853 ν 3 = 55.4 R 6 = -9.13 D 6 = 2.00 R 7 = Aperture D 7 = Variable R 8 = -22.13 D 8 = 1.80 N 4 = 1.58306 ν 4 = 30.2 R 9 = -19.45 D 9 = 3.23 R10 = -9.59 D10 = 1.00 N 5 = 1.60300 ν 5 = 65.5 R11 = -38.74

[0047]

[Table 5] Aspheric surface coefficient 8th surface: A = 0 B = 6.210 e-05 C = 7.211 e-07 D = 2.326
e-09 E = 0 <Numerical example 6> F = 39.00 to 58.01 Fno = 7.30 to 10.9 2ω = 58.0 ° to 40.9 ° R 1 = 10.75 D 1 = 1.80 N 1 = 1.57135 ν 1 = 53.0 R 2 = -229.35 D 2 = 0.26 R 3 = -13.66 D 3 = 2.00 N 2 = 1.83400 ν 2 = 37.2 R 4 = 14.19 D 4 = 0.19 R 5 = 26.69 D 5 = 3.50 N 3 = 1.74319 ν 3 = 49.3 R 6 = -10.34 D 6 = 1.40 R 7 = Aperture D 7 = Variable R 8 = -24.39 D 8 = 2.00 N 4 = 1.58306 ν 4 = 30.2 R 9 = -17.38 D 9 = 3.17 R10 = -9.60 D10 = 0.90 N 5 = 1.65829 ν 5 = 57.3 R11 = -47.50

[0048]

[Table 6] Aspheric surface coefficient 8th surface: A = 0 B = 8.427 e-05 C = 1.121 e-07 D = 9.318
e-09 E = 0 <Numerical Example 7> F = 38.01 to 67.80 Fno = 6.80 to 12.12 ω = 59.3 ° to 35.4 ° R 1 = 10.40 D 1 = 1.80 N 1 = 1.51633 ν 1 = 64.2 R 2 = -78.56 D 2 = 0.28 R 3 = -12.51 D 3 = 1.60 N 2 = 1.78589 ν 2 = 44.2 R 4 = 13.15 D 4 = 0.13 R 5 = 23.06 D 5 = 3.63 N 3 = 1.67790 ν 3 = 55.3 R 6 = -9.50 D 6 = 1.80 R 7 = Aperture D 7 = Variable R 8 = -21.26 D 8 = 2.00 N 4 = 1.58306 ν 4 = 30.2 R 9 = -17.31 D 9 = 3.53 R10 = -9.59 D10 = 1.20 N 5 = 1.60311 ν 5 = 60.7 R11 = -51.07

[0049]

[Table 7] Aspherical coefficient 8th surface: A = 0 B = 8.235 e-05 C = 6.048 e-07 D = 2.313
e-09 E = 0 <Numerical Example 8> F = 29.00 to 43.89 Fno = 8.00 to 12.1 2 ω = 73.4 ° to 52.5 ° R 1 = 9.92 D 1 = 1.80 N 1 = 1.51633 ν 1 = 64.2 R 2 = 142.54 D 2 = 0.44 R 3 = -15.48 D 3 = 2.10 N 2 = 1.77664 ν 2 = 40.6 R 4 = 10.83 D 4 = 0.30 R 5 = 14.84 D 5 = 3.49 N 3 = 1.69999 ν 3 = 53.4 R 6 = -10.93 D 6 = 0.79 R 7 = Aperture D 7 = Variable R 8 = -43.15 D 8 = 2.20 N 4 = 1.58306 ν 4 = 30.2 R 9 = -23.37 D 9 = 4.71 R10 = -11.14 D10 = 1.00 N 5 = 1.69349 ν 5 = 50.8 R11 = -63.91

[0050]

[Table 8] Aspherical surface 1st surface: A = 0 B = -4.547 e-05 C = 2.463 e-07 D = 0 E = 0 8th surface: A = 0 B = 4.352 e-05 C = 7.511 e-07 D = -5.122 e-09 E = 0

[0051]

[Table 9]

[0052]

According to the present invention, the total lens length can be shortened by setting the lens configuration of each lens group of the zoom lens that performs zooming by moving two lens groups having a predetermined refractive power. It is possible to achieve a compact zoom lens having a simple configuration, which has high optical performance over the entire zoom range of a zoom ratio of about 1.5 to 2.0.

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view of Numerical Example 1 of the present invention.

FIG. 2 is a lens cross-sectional view of Numerical Example 2 of the present invention.

FIG. 3 is a lens cross-sectional view of Numerical Example 3 of the present invention.

FIG. 4 is a lens cross-sectional view of Numerical Example 4 of the present invention.

FIG. 5 is a lens cross-sectional view of Numerical Example 5 of the present invention.

FIG. 6 is a sectional view of a lens according to a numerical example 6 of the present invention.

FIG. 7 is a lens cross-sectional view of Numerical Example 7 of the present invention.

FIG. 8 is a sectional view of a lens according to a numerical example 8 of the present invention.

FIG. 9 is an aberration diagram at the wide-angle end according to Numerical Example 1 of the present invention.

FIG. 10 is an intermediate aberration diagram of Numerical Example 1 of the present invention.

FIG. 11 is an aberration diagram at a telephoto end according to Numerical Example 1 of the present invention.

FIG. 12 is an aberration diagram at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 13 is an intermediate aberration diagram of Numerical example 2 of the present invention.

FIG. 14 is an aberration diagram at a telephoto end according to Numerical Example 2 of the present invention.

FIG. 15 is an aberration diagram at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 16 is an intermediate aberration diagram of Numerical example 3 of the present invention.

FIG. 17 is an aberration diagram at a telephoto end according to Numerical Example 3 of the present invention.

FIG. 18 is an aberration diagram at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 19 is an intermediate aberration diagram of Numerical Example 4 of the present invention.

FIG. 20 is an aberration diagram at a telephoto end according to Numerical Example 4 of the present invention.

FIG. 21 is an aberration diagram at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 22 is an intermediate aberration diagram of Numerical example 5 of the present invention.

FIG. 23 is an aberration diagram at a telephoto end according to Numerical Example 5 of the present invention.

FIG. 24 is an aberration diagram at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 25 is an intermediate aberration diagram of Numerical Example 6 of the present invention.

FIG. 26 is an aberration diagram at a telephoto end according to Numerical Example 6 of the present invention.

FIG. 27 is an aberration diagram at a wide-angle end according to Numerical Example 7 of the present invention.

FIG. 28 is an intermediate aberration diagram of Numerical Example 7 of the present invention.

FIG. 29 is an aberration diagram at a telephoto end according to Numerical Example 7 of the present invention.

FIG. 30 is an aberration diagram at a wide-angle end according to Numerical Example 8 of the present invention.

FIG. 31 is an intermediate aberration diagram of Numerical Example 8 of the present invention.

FIG. 32 is an aberration diagram at a telephoto end according to Numerical Example 8 of the present invention.

[Explanation of symbols]

 L1 First group L2 Second group SP Aperture IP Image plane d d line g g line S Sagittal image plane M Meridional image plane

Claims (5)

[Claims] 1. A compact zoom lens system having two lens units, a first lens unit having a positive refractive power and a second lens unit having a negative refractive power, which are arranged in order from the object side, and performing zooming by changing the distance between both lens units. In the lens, the first group is a positive first lens having a convex surface directed toward the object side,
The lens has three lenses, a negative second lens whose both lens surfaces are concave surfaces, and a positive third lens whose both lens surfaces are convex surfaces.
The group has two lenses, a meniscus-shaped positive fourth lens having a convex surface directed toward the image side and a meniscus-shaped negative fifth lens having a convex surface directed toward the image side, and the focal length of the first group F1,
The focal length of the entire system at the wide-angle end is fw, the air distance between the first lens and the second lens is D2, the air distance between the second lens and the third lens is D4, and the distance from the object-side lens surface of the first lens to the first lens When the length of the three lenses to the lens surface on the image plane side is DL1, 0.5 <f1 / fw <0.9 0.1 <DL1 / fw <0.35 0.005 <(D2 + D4) / fw < A compact zoom lens that satisfies the condition of 0.03. 2. At the wide angle end, when the distance from the object-side lens surface of the first lens to the image surface is Lw, the condition of 0.9 <Lw / fw <1.2 is satisfied. The compact zoom lens according to claim 1. 3. When the radius of curvature of the image side lens surface of the second lens is R4, the radius of curvature of the object side lens surface of the third lens is R5, and the lens thickness of the second lens is D3. The compact zoom lens according to claim 2, wherein the condition of 0.5 <R4 / R5 <0.9 0.035 <D3 / fw <0.08 is satisfied. 4. The compact zoom lens according to claim 1, wherein a condition of 0.1 <fw / f4 <0.5 is satisfied, where f4 is a focal length of the fourth lens. 5. The condition of 1.55 <N5 <1.73 50 <ν5 is satisfied when the refractive index and the Abbe number of the material of the fifth lens are N5 and ν5, respectively. Small zoom lens.