JPH08248319A - Zoom lens - Google Patents

Abstract

PURPOSE: To obtain a zoom lens which has four lens groups as a whole, whose moving condition associated with the refractive power and the variable power of the respective lens groups is appropriately set and which has high optical performance over a front variable power range. CONSTITUTION: This zoom lens has four lens groups, that is, the 1st group L1 having positive refractive power, the 2nd group L2 having negative refractive power, the 3rd group L3 having the positive refractive power, and the 4th group L4 having the positive refractive power in order from an object side. In the case of varying the power from a wide-angle end to a telephoto end, the respective lens groups are moved so that a distance between the 1st group L1 and the 2nd group L2 may be increased, a distance between the 2nd group L2 and the 3rd group L3 may be decreased, and a distance between the 3rd group L3 and the 4th group L4 may be decreased; then the focal distance (fi) of the 1st group and the focal distance (fw) of the entire system at the wide-angle end are appropriately set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens, and in particular, has a shooting angle of view of about 84 degrees at the wide-angle end and an F number of 3.6.
Up to about 5.7 and a zoom ratio of about 4 to 5.3, which has good optical performance over the entire zoom range, is suitable for photographic cameras, video cameras, electronic still cameras, etc. It relates to a corner zoom lens.

[0002]

2. Description of the Related Art Conventionally, a zoom lens having a high zoom ratio, a wide angle of view, a high contrast and a high optical performance over the entire zoom range has been required for a photographing system such as a photographic camera or a video camera. There is. In Japanese Patent Laid-Open No. 60-14213 and Japanese Patent Laid-Open No. 60-14214, there are four lens groups having positive, negative, positive, and positive refractive powers in order from the object side, and the photographing angle of view at the wide-angle end is 60. A zoom lens with a magnification of about 3 to 6 has been proposed. JP-A-63-665
According to Japanese Patent Laid-Open No. 23-43506 and Japanese Patent Application Laid-Open No. 63-294506, the lens group consists of four lens groups having positive, negative, positive, and positive refracting powers in order from the object side. A zoom lens having a ratio of about 3 to 4 has been proposed.

In addition, in JP-A-62-247316 and JP-A-62-24213, the first group having a positive refractive power, the second group having a negative refractive power, and the positive refractive power are sequentially arranged from the object side. Of the third lens group and a fourth lens group of positive refractive power, the second lens group is moved to perform zooming, and the fourth lens group is moved to change the image plane due to zooming. I'm focusing. Further, in JP-A-58-160913, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power are arranged in this order from the object side. In this case, the first lens group and the second lens group are moved to perform zooming, and the image plane variation associated with zooming is moved to the fourth group. Then, focusing is performed by moving one or more lens groups among these lens groups.

[0004]

Generally, in a 4-group zoom lens composed of four lens groups having positive, negative, positive, and positive refractive powers in order from the object side, the photographing field angle at the wide-angle end is 8
In order to maintain a high optical performance over the entire zoom range while achieving a wide angle of view of approximately 4 degrees and a high zoom ratio of approximately 4-5, each lens system is configured to obtain a predetermined aperture ratio. It is important to set the optical constants of the lens group appropriately.

For example, in the above-mentioned four-group zoom lens,
If the moving conditions of each lens unit associated with zooming, the refracting power of each lens unit, and the zooming ratio and magnification of the second lens unit that performs zooming are not set appropriately, the occurrence of various aberrations will increase and good image quality will be obtained. It becomes difficult to get the video of.

According to the present invention, in the four-group zoom lens, a wide-angle lens is mainly set by appropriately setting the moving condition of each lens group associated with zooming, the refractive power of each lens group, and the zoom ratio of the second group. It is an object of the present invention to provide a zoom lens having a high optical performance over the entire zoom range with an edge shooting angle of view of about 84 degrees and a zoom ratio of about 4-5.

[0007]

A zoom lens according to the present invention comprises, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive lens group. The fourth of refractive power
When the magnification is changed from the wide-angle end to the telephoto end, the distance between the first group and the second group is increased, and the distance between the second group and the third group is increased. Decreased, the third group and the fourth group
The groups are moved so that the distance between the groups decreases, the focal length of the i-th group is fi, and the focal length of the entire system at the wide-angle end is fw.
It is characterized by satisfying the following condition: 0.13 <| f2 | / f1 <0.19 (1) 1.4 <f3 / fw <2.0 (2).

[0008]

1 to 6 are sectional views of lenses at wide-angle end according to Numerical Embodiments 1 to 6 of the present invention. 7 to 12 are aberration diagrams of Numerical Examples 1 to 6 of the present invention. In the aberration diagrams, (A) shows the wide-angle end and (B) shows the telephoto end.

In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and L4.
Is a fourth lens unit having a positive refracting power, and SP is a diaphragm provided in front of the third lens unit.

In this embodiment, when zooming from the wide-angle end to the telephoto end, the second lens unit has a convex locus toward the object side as shown by the arrow, and the first, third, and fourth lens units move toward the object side. The distance between the first lens group and the second lens group is increased, the distance between the second lens group and the third lens group is decreased, and the distance between the third lens group and the fourth lens group is decreased. The diaphragm SP is moved integrally with the third lens group.

In this embodiment, as described above, the refractive powers of the four lens groups and the moving conditions of each lens group due to zooming are set, and the refractive powers of the first, second, and third lens groups are expressed by conditional expression (1). ),
It is set to satisfy (2). As a result, the zooming is distributed in a well-balanced manner to each lens group, facilitating high zooming, and performing good aberration correction over the entire zooming range, especially in the intermediate zoom range.

Next, the technical meaning of the conditional expressions (1) and (2) will be described. Conditional expression (1) defines the ratio of the focal length of the second lens unit to the focal length of the first lens unit. If the focal length of the second lens unit becomes shorter than the lower limit value, it is advantageous for high zooming and compactness, but the aberration variation due to zooming becomes large and it becomes difficult to correct aberrations satisfactorily. On the other hand, if the focal length of the second lens unit becomes longer than the upper limit, it becomes difficult to achieve high zoom ratio and compact size, which is not preferable.

Conditional expression (2) defines the ratio of the focal length of the third lens group to the focal length of the entire system at the wide-angle end.
If the focal length of the third lens unit becomes shorter than the lower limit value, it is advantageous for size reduction. However, various aberrations, especially spherical aberration, generated in the third lens unit become large, and this can be corrected by another lens unit. It will be difficult. Further, in order to suppress spherical aberration in the third lens group, it is necessary to increase the number of lenses, which is not preferable. On the other hand, if the focal length of the third lens unit becomes longer than the upper limit, the effect of multiple lens units becomes small, and the total lens length and lens outer diameter increase, which is not preferable.

According to the present invention, with the above-described structure, the photographing angle of view at the wide angle end is as wide as 84 degrees, the zoom ratio is about 4 to 5.3, and the F number is about 3.6 to 5.7. We have obtained a zoom lens with good optical performance over the zoom range.

Further, in the present invention, the focusing is performed by moving the second lens group, which prevents an increase in the outer diameter of the lens of the first lens group as compared with the case where the first lens group is focused, while taking a picture. We are trying to shorten the shortest possible distance.
An aspherical surface with a positive refractive power increasing from the lens center to the lens periphery is used for the convex lens surface of the meniscus negative lens in the second lens group, and one lens surface in the fourth lens group from the lens center By using an aspherical surface in which the negative refracting power becomes weaker toward the periphery of the lens, spherical aberration, astigmatism, and field curvature are mainly corrected in a well-balanced manner. Especially, the high-order field curvature on the wide-angle side is well corrected.

The zoom lens according to the present invention can be achieved by satisfying the above-mentioned various conditions. However, it is possible to satisfactorily correct the aberration variation when achieving a wider angle of view and a higher zoom ratio, and to obtain high optical performance. In order to obtain it, it is better to satisfy at least one of the following conditions.

(1-1) The first group includes a cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens are cemented together, and a positive meniscus lens having a convex surface facing the object side. The second group includes a meniscus negative lens having a convex surface facing the object side, a negative lens having a concave surface on both lens surfaces, a positive lens having a convex surface on both lens surfaces, and a negative lens having a concave surface on the object side. It is to have. As a result, the outer diameter of the lens of the first lens group is reduced to achieve compactness,
Also, various aberrations are satisfactorily corrected over the entire zoom range while achieving a wide angle of view at the wide-angle end.

(1-2) The third group has at least two positive lenses and a negative lens having a concave surface facing the object side. As a result, the fluctuation of various aberrations due to zooming is reduced while ensuring a predetermined zoom ratio. Especially, the variation of spherical aberration is well corrected over the entire zoom range.

(1-3) When the focal length of the entire system at the telephoto end is fT, the condition of 2.8fw <f1 <0.8fT (3) should be satisfied.

Conditional expression (3) defines the focal length of the first lens unit by the ratio of the focal length of the entire system at the wide-angle end to the focal length of the entire system at the telephoto end. If the focal length of the first lens unit becomes short beyond the lower limit, it becomes difficult to correct spherical aberration especially on the telephoto side. Further, since the first lens group has a relatively large diameter, the lens weight and cost increase as the refractive power of the lens surface increases, which is not preferable. If the focal length of the first lens unit becomes shorter than the upper limit, the amount of movement of the first lens unit for zooming becomes large, and the lens outer diameter also becomes large, making it difficult to make it compact.

(1-4) When the variable power ratios of the second group and the entire system are Z2 and Z, respectively, the condition of 0.48 <Z2 / Z <0.55 (4) must be satisfied. Is.

Conditional expression (4) is the second equation for the variable power ratio of the entire system.
It defines the ratio of the variable power ratio of the group, and represents the ratio of variable power distribution in the second group. For a zoom lens having a zoom ratio of 3 or less, it is an efficient zoom method that most of zooming is performed by the second lens unit. However, when a high zoom ratio of 3 or more is achieved, the zoom ratio in the second group becomes large. For this reason, in the present embodiment, the variable power share of the second lens group is reduced and the other lens groups (particularly the fourth lens group) are responsible for the variable power. When the upper limit value is exceeded and the variable-magnification share of the second lens group increases, aberration variation increases and correction becomes difficult.
Further, when the lower limit is exceeded and the variable power share of the second lens group becomes small, the variable power share of the other lens groups (particularly the fourth lens group) increases, and efficient zooming cannot be performed, resulting in a disadvantage in compactness. .

Next, numerical examples of the present invention will be shown. In 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 in order from the object side, and Ni and vi are the i-th lens in order from the object side, respectively. Is the refractive index and Abbe number of the glass. Table 1 shows the relationship between the above-mentioned conditional expressions and various numerical values in the numerical examples. When the aspherical shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the traveling direction of light is positive, R is the paraxial radius of curvature, and B, C, D, and E are aspherical coefficients, respectively.

[0024]

[Equation 1] It is expressed by the formula. Further, "e-0X" means "10 ^-X ".

<Numerical Example 1> f = 24.8 to 101.8 FNo = 1: 3.6 to 5.6 2 ω = 82.1 ° to 24.0 ° R 1 = 134.99 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 53.27 D 2 = 7.50 N 2 = 1.65 160 ν 2 = 58.5 R 3 = 960.25 D 3 = 0.15 R 4 = 41.36 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 111.18 D 5 = Variable R 6 = 91.80 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 11.81 D 7 = 5.20 R 8 = -38.60 D 8 = 1.10 N 5 = 1.77250 ν 5 = 49.6 R 9 = 34.41 D 9 = 0.15 R10 = 22.18 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -35.71 D11 = 0.80 R12 = -23.39 D12 = 1.10 N 7 = 1.83481 ν 7 = 42.7 R13 = 1089.77 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 27.03 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -62.12 D16 = 0.22 R17 = 22.33 D17 = 4.50 N 9 = 1.55963 ν 9 = 61.2 R18 = -16.70 D18 = 0.10 R29 = -16.28 D19 = 1.00 N10 = 1.80610 ν10 = 41.0 R20 = 38.17 D20 = Variable R21 = 26.98 D21 = 5.50 N11 = 1.60311 ν11 = 60.7 R22 = -20.54 D22 = 1.59 R23 = -66.62 D23 = 1.80 N12 = 1.85026 ν12 = 32.3 R24 = 60.74

[0026]

[Table 1] Numerical Example 2 f = 24.9 to 101.8 FNo = 1: 3.6 to 5.7 2ω = 82.0 ° to 24.0 ° R 1 = 188.27 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 61.32 D 2 = 7.50 N 2 = 1.65160 ν 2 = 58.5 R 3 = -937.50 D 3 = 0.15 R 4 = 41.52 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 102.15 D 5 = variable R 6 = 131.18 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 12.16 D 7 = 5.20 R 8 = -41.38 D 8 = 1.10 N 5 = 1.77250 ν 5 = 49.6 R 9 = 32.72 D 9 = 0.15 R10 = 22.45 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -36.60 D11 = 0.80 R12 = -24.83 D12 = 1.10 N 7 = 1.83481 ν 7 = 42.7 R13 = -10577.33 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 26.64 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -64.72 D16 = 0.22 R17 = 21.70 D17 = 4.50 N 9 = 1.55963 ν 9 = 61.2 R18 = -16.23 D18 = 0.10 R29 = -15.92 D19 = 1.00 N10 = 1.80610 ν10 = 41.0 R20 = 35.62 D20 = Variable R21 = 25.27 D21 = 5.50 N11 = 1.60311 ν11 = 60.7 R22 = -21.67 D22 = 1.59 R23 = -113.40 D23 = 1.80 N12 = 1.85026 ν12 = 32.3 R24 = 43.78

[0027]

[Table 2] <Numerical Example 3> f = 24.9 to 130.0 FNo = 1: 3.6 to 5.8 2ω = 82.0 ° to 18.9 ° R 1 = 170.76 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 60.56 D 2 = 8.00 N 2 = 1.65160 ν 2 = 58.5 R 3 = -710.16 D 3 = 0.15 R 4 = 42.98 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 106.36 D 5 = variable R 6 = 93.48 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 12.86 D 7 = 5.20 R 8 = -45.73 D 8 = 1.10 N 5 = 1.77250 ν 5 = 49.6 R 9 = 37.75 D 9 = 0.15 R10 = 22.09 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -38.13 D11 = 0.80 R12 = -27.77 D12 = 1.10 N 7 = 1.83481 ν 7 = 42.7 R13 = 73.56 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 27.93 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -84.58 D16 = 0.22 R17 = 22.39 D17 = 4.50 N 9 = 1.55963 ν 9 = 61.2 R18 = -17.50 D18 = 0.10 R29 = -17.34 D19 = 1.00 N10 = 1.80610 ν10 = 41.0 R20 = 36.67 D20 = variable R21 = 25.88 D21 = 5.50 N11 = 1.60311 ν11 = 60.7 R22 = -24.57 D22 = 1.59 R23 = -208.55 D23 = 1.80 N12 = 1.85026 ν12 = 32.3 R24 = 45.45

[0028]

[Table 3] <Numerical Example 4> f = 24.9 to 129.9 FNo = 1: 3.6 to 5.7 2ω = 82.0 ° to 18.9 ° R 1 = 168.46 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 59.87 D 2 = 8.00 N 2 = 1.65160 ν 2 = 58.5 R 3 = -2639.15 D 3 = 0.15 R 4 = 44.68 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 123.07 D 5 = Variable R 6 = 133.41 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 13.01 D 7 = 5.20 R 8 = -54.44 D 8 = 1.10 N 5 = 1.77250 ν 5 = 49.6 R 9 = 37.30 D 9 = 0.15 R10 = 23.03 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -36.76 D11 = 0.80 R12 = -27.70 D12 = 1.50 N 7 = 1.83481 ν 7 = 42.7 R13 = 112.95 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 49.89 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -258.58 D16 = 0.22 R17 = 18.43 D17 = 5.00 N 9 = 1.55963 ν 9 = 61.2 R18 = -19.97 D18 = 0.10 R29 = -20.08 D19 = 1.50 N10 = 1.80440 ν10 = 39.6 R20 = 57.26 D20 = variable R21 = 50.49 D21 = 2.80 N11 = 1.55963 ν11 = 61.2 R22 = 101.39 D22 = 0.20 R23 = 32.73 D23 = 4.00 N12 = 1.60311 ν12 = 60.7 R24 = -28.34 D24 = 1.59 R25 = -110.43 D25 = 1.80 N13 = 1.85026 ν13 = 32.3 R26 = 49.52

[0029]

[Table 4] <Numerical Example 5> f = 24.8 to 131.7 FNo = 1: 3.6 to 5.7 2ω = 82.2 ° to 18.7 ° R 1 = 169.69 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 60.98 D 2 = 7.50 N 2 = 1.65160 ν 2 = 58.5 R 3 = -890.35 D 3 = 0.15 R 4 = 43.23 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 104.18 D 5 = Variable R 6 = 111.37 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 12.76 D 7 = 5.20 R 8 = -46.69 D 8 = 1.10 N 5 = 1.77250 ν 5 = 49.6 R 9 = 36.72 D 9 = 0.15 R10 = 23.07 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -34.20 D11 = 0.80 R12 = -23.89 D12 = 1.10 N 7 = 1.83481 ν 7 = 42.7 R13 = 197.01 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 23.61 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -87.75 D16 = 0.22 R17 = 28.68 D17 = 4.50 N 9 = 1.55963 ν 9 = 61.2 R18 = -16.13 D18 = 0.10 R29 = -15.94 D19 = 1.00 N10 = 1.80610 ν10 = 41.0 R20 = 37.48 D20 = variable R21 = 23.35 D21 = 5.50 N11 = 1.60311 ν11 = 60.7 R22 = -25.76 D22 = 1.59 R23 = -494.36 D23 = 1.80 N12 = 1.85026 ν12 = 32.3 R24 = 39.43

[0030]

[Table 5] <Numerical Example 6> f = 24.8 to 129.9 FNo = 1: 3.6 to 5.7 2ω = 82.1 ° to 18.9 ° R 1 = 163.48 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.8 R 2 = 59.46 D 2 = 8.00 N 2 = 1.65160 ν 2 = 58.5 R 3 = -5151.49 D 3 = 0.15 R 4 = 45.71 D 4 = 6.50 N 3 = 1.77250 ν 3 = 49.6 R 5 = 131.59 D 5 = variable R 6 = 137.63 D 6 = 1.20 N 4 = 1.80610 ν 4 = 41.0 R 7 = 13.48 D 7 = 5.20 R 8 = -57.86 D 8 = 1.50 N 5 = 1.77250 ν 5 = 49.6 R 9 = 34.90 D 9 = 0.15 R10 = 23.19 D10 = 4.00 N 6 = 1.84666 ν 6 = 23.9 R11 = -36.41 D11 = 0.80 R12 = -26.68 D12 = 1.50 N 7 = 1.83481 ν 7 = 42.7 R13 = 125.36 D13 = Variable R14 = (Aperture) D14 = 1.00 R15 = 61.96 D15 = 3.00 N 8 = 1.60311 ν 8 = 60.7 R16 = -185.44 D16 = 0.22 R17 = 18.78 D17 = 5.00 N 9 = 1.55963 ν 9 = 61.2 R18 = -20.81 D18 = 0.10 R29 = -20.38 D19 = 1.50 N10 = 1.80440 ν10 = 39.6 R20 = 62.57 D20 = variable R21 = 51.91 D21 = 2.80 N11 = 1.55963 ν11 = 61.2 R22 = 81.78 D22 = 0.20 R23 = 31.89 D23 = 4.00 N12 = 1.60311 ν12 = 60.7 R24 = -25.43 D24 = 1.59 R25 = -92.54 D25 = 1.80 N13 = 1.85026 ν13 = 32.3 R26 = 52.72

[0031]

[Table 6]

[0032]

As described above, according to the present invention, in the four-group zoom lens, the moving conditions of each lens group, the refractive power of each lens group, and the zoom ratio of the second group are mainly involved. It is possible to achieve a zoom lens having high optical performance over the entire zoom range with a shooting angle of view at the wide-angle end of about 84 degrees and a zoom ratio of about 4 to 5 by appropriately setting the above. .

[Brief description of drawings]

FIG. 1 is a lens cross-sectional view at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 2 is a lens cross-sectional view at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 3 is a lens cross-sectional view at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 4 is a lens cross-sectional view at a wide-angle end according to Numerical Example 4 of the present invention.

FIG. 5 is a lens cross-sectional view at a wide-angle end according to Numerical Example 5 of the present invention.

FIG. 6 is a lens cross-sectional view at a wide-angle end according to Numerical Example 6 of the present invention.

FIG. 7 is an aberration diagram of Numerical example 1 of the present invention.

FIG. 8 is an aberration diagram of Numerical example 2 of the present invention.

FIG. 9 is an aberration diagram of Numerical example 3 of the present invention.

FIG. 10 is an aberration diagram of Numerical example 4 of the present invention.

FIG. 11 is an aberration diagram of Numerical example 5 of the present invention.

FIG. 12 is an aberration diagram of Numerical example 6 of the present invention.

[Explanation of symbols]

 L1 1st group L2 2nd group L3 3rd group L4 4th group SP Aperture stop SK Fixed stop d d line g g line S.I. C Sine condition S Sagittal image plane M Meridional image plane

Claims (8)

[Claims] 1. Four lens groups, in order from the object side, a first group having a positive refractive power, a second group having a negative refractive power, a third group having a positive refractive power, and a fourth group having a positive refractive power. In zooming from the wide-angle end to the telephoto end, the distance between the first lens group and the second lens group increases, and the distance between the second lens group and the third lens group decreases, The group and the fourth group are moved so that the distance between them decreases.
When the focal length of the i-th group is fi and the focal length of the entire system at the wide-angle end is fw, 0.13 <| f2 | / f1 <0.19 1.4 <f3 / fw <2.0 A zoom lens that is characterized by its satisfaction. 2. The zoom lens according to claim 1, wherein the condition of 2.8fw <f1 <0.8fT is satisfied when the focal length of the entire system at the telephoto end is fT. 3. The variable power ratios of the second group and the entire system are Z2 and Z2, respectively.
The zoom lens according to claim 2, wherein a condition of 0.48 <Z2 / Z <0.55 when Z is satisfied is satisfied. 4. The cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens are cemented together, and a positive meniscus lens having a convex surface facing the object side, The second group includes a meniscus negative lens having a convex surface directed toward the object side, a negative lens having both concave lens surfaces, a positive lens having both convex lens surfaces, and a negative lens having a concave surface directed to the object side. The zoom lens according to claim 1, wherein 5. The zoom lens according to claim 1, wherein the third group includes at least two positive lenses and a negative lens having a concave surface facing the object side. 6. The zoom lens according to claim 5, wherein the first lens unit moves toward the object side during zooming from the wide-angle end to the telephoto end. 7. The zoom lens according to claim 6, wherein at least one lens surface of the second group and / or the fourth group is an aspherical surface. 8. The zoom lens according to claim 1, wherein the second lens unit is moved along the optical axis for focusing.