JPH0886963A - Zoom lens - Google Patents

Abstract

PURPOSE: To obtain a zoom lens having high optical performance over an entire variable-power range and also over an entire screen by adequately setting the moving condition of each lens group in accordance with variable power, the refracting power of each lens group and the variable power ratio of a second group with four-lens constitution. CONSTITUTION: The four lens groups respectively having positive or negative refracting power are disposed. The respective lens groups are moved to an object side, so that an interval between the first group L1 and the second group L2 is increased and the intervals between the second group L2 and the third group L3, and between the third group L3 and the fourth group L4 are decreased respectively in the case of variable power from a wide-angle end to a telephotographic end. The fourth group L4 has three components respectively having positive, positive and negative refracting power, and the next conditions of 0.05<|f2|/fT<0.09, 0.3<f1/fT<0.7, 0.2<f4/fT0.4, and 3<Z2<4 are satisfied when the focal distance of an (i) group is defined as (fi), the focal distance of an entire system on the wide-angle end and on the telephotographic end are respectively defined as (fw) and fT, and the power variation ratio of the second group L2 is defined as Z2.

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 more particularly, a shooting angle of view at the wide-angle end is about 75 degrees and an F number of 4 to 6 is used.
A zoom lens having a high zoom ratio and a wide angle of view, which is suitable for a photographic camera, a video camera, an electronic still camera and the like having good optical performance over the entire zoom range of about 6 to 7 zoom ratios. Is.

[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 is 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 Japanese Patent Laid-Open No. 4-70708, positive, negative, and
It consists of five lens groups with positive, positive and negative refractive power,
A zoom lens with a shooting angle of view at the wide-angle end of about 70 degrees and a zoom ratio of about 7 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.

In JP-A-58-160913, the first group having a positive refractive power and the second group having a negative refractive power are arranged in this order from the object side.
An image associated with zooming, which has four lens groups, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, and moving the first lens group and the second lens group for zooming. The surface movement is performed by moving the fourth group. Then, focusing is performed by moving one or more lens groups among these lens groups.

[0005]

Generally, in a four-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 7
In order to maintain a high optical performance over the entire zoom range and obtain a predetermined aperture ratio while achieving a wide angle of view of about 5 degrees and a high zoom ratio of about 6 to 7, each lens system is configured. 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 a 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 zooming ratio of the second group. It is an object of the present invention to provide a zoom lens having an optical angle of view of about 75 degrees, a zoom ratio of about 6 to 7, and a high optical performance over the entire screen.

[0008]

The zoom lens of the present invention comprises (1-1) a first group having a positive refractive power, a second group having a negative refractive power, and a third group having a positive refractive power in order from the object side. And a fourth lens unit having a positive refracting power, that is, the fourth lens unit, and the first lens unit and the second lens unit when moving the zoom lens from the wide-angle end to the telephoto end.
The distance between the groups increases, the distance between the second and third groups decreases,
The third lens unit and the fourth lens unit are moved so that the distance between them decreases. The fourth lens unit has a positive refractive power 41st component, a positive refractive power 42nd component, and a negative refractive power It has three components of 43 components, and has an aspherical surface whose positive refractive power becomes weaker from the lens center to the lens periphery. The focal length of the i-th group is fi, the wide-angle end and the telephoto end. When the focal lengths of the entire system at the edges are fw and fT and the zoom ratio of the second lens unit is Z2, 0.05 <| f2 | / fT <0.09 (1a) 0.3 <f1 / fT <0.7 (2a) 0.2 <f4 / fT <0.4 (3a) 3 < Z2 <4 (4a) is satisfied.

(1-2) In order from the object side, the first group of positive refracting power, the second group of negative refracting power, the third group of positive refracting power, and the fourth group of positive refracting power When the magnification is changed from the wide-angle end to the telephoto end, each lens group is moved toward the object side, and the distance between the first and second groups is increased, and the distance between the second and third groups is increased. The third lens unit is moved so that the distance between the third lens unit and the fourth lens unit is reduced, and the focus is moved by moving the second lens unit on the optical axis. The focal lengths of the entire system at the end and the telephoto end are fw and fT, respectively.
When the zoom ratio of the group and the magnification at the telephoto end are Z2 and β2T, respectively, 0.05 <| f2 | / fT <0.09 ... (1b) 0.3 <f1 / fT <0.7 (2b) 0.2 <f4 / fT <0.4 (3b) 3 <Z2 <4 ...・ ・ ・ ・ ・ ・ ・ ・ (4b) | β2T | <1 ・ ・ ・ (5b) .

[0010]

1 to 3 are lens cross-sectional views at the wide-angle end in Numerical Embodiments 1 to 3 of the present invention.

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. SK is a fixed diaphragm. The fourth lens unit L4 has three components, that is, a 41st component L41 having a positive refractive power, a 42nd component L42 having a positive refractive power, and a 43rd component L43 having a negative refractive power.

In this embodiment, at the time of zooming from the wide-angle end to the telephoto end, each lens unit is moved toward the object side as shown by an arrow.
The distance between the groups is increased, the distance between the second group and the third group is decreased, and the distance between the third group and the fourth group is decreased.
The diaphragm SP is moved integrally with the third lens group.

In the present embodiment, as described above, the refractive powers of the four lens groups and the moving conditions of each lens group associated with zooming are set, and the lens structure of the fourth lens group is made up of three components. Further, an aspherical surface having a shape in which the positive refractive power becomes weaker from the lens center to the lens periphery is provided in the fourth lens unit.

According to the present invention, with the above construction, the photographing angle of view at the wide angle end is 75 degrees, and the zoom ratio is about 6 to 7 at the wide angle of view and F
A zoom lens having good optical performance over the entire zoom range of Nos. 4 to 6 is obtained. In particular, residual aberrations due to the lens systems from the first group to the third group are satisfactorily corrected by the fourth group composed of three components as described above.

Further, in the present invention, the focusing is carried out by moving the second lens group, thereby preventing the increase of the outer diameter of the lens of the first lens group and shortening the close-up distance at which the image can be taken. By using the aspherical surface having the above-described shape in the fourth lens unit, spherical aberration, astigmatism, and field curvature are mainly corrected in good balance. Especially, the high-order field curvature on the wide-angle side is well corrected.

Next, the technical meaning of the above conditional expression will be described. The conditional expressions (1a) to (4a) according to the first aspect of the invention.
Is the same as the conditional expressions (1b) to (4b) according to the second aspect of the invention, and therefore will be described below as conditional expressions (1) to (4).

Conditional expression (1) defines the ratio between the focal length of the second lens unit having negative refractive power and the focal length of the entire system at the telephoto end, and achieves a high zoom ratio while mainly shortening the total lens length. It is for. If the lower limit of conditional expression (1) is exceeded and the negative refractive power of the second lens unit becomes too strong, it is advantageous for compactness, but it becomes difficult to correct aberrations, and if it exceeds the upper limit, it is advantageous for aberration correction. However, the total length of the lens increases, which is not preferable.

Conditional expression (2) defines the ratio of the focal length of the first lens unit having a positive refractive power to the focal length of the entire system at the telephoto end, and mainly reduces the lens outer diameter of the third lens unit at the telephoto end. In addition, a high zoom ratio can be easily achieved. If the lower limit of conditional expression (2) is exceeded and the positive refracting power of the first lens unit becomes too strong, aberrations on the telephoto side, particularly spherical aberration, that occur in this first lens unit will increase. It becomes difficult to correct in a good balance. If the upper limit is exceeded and the positive refractive power of the first lens unit becomes weaker, it becomes difficult to make it compact.

Conditional expression (3) defines the ratio of the focal length of the fourth lens unit having a positive refractive power to the focal length of the entire system at the telephoto end, and is mainly used for achieving high zoom ratio and compactness. It is a thing.
When the value exceeds the lower limit of conditional expression (3) and the positive refractive power of the fourth lens unit becomes too strong, it is advantageous for downsizing and high zooming, but various aberrations, particularly curvature of field, deteriorate. If the upper limit is exceeded and the refracting power of the fourth lens unit becomes too weak, it becomes difficult to achieve compactness and high zoom ratio.

Conditional expression (4) defines the variable power distribution of the second lens unit upon zooming from the wide-angle end to the telephoto end, and the variable power distribution of the second lens unit is expressed by the conditional expression (4). By setting the range, a compact and paraxial arrangement that can achieve good performance has been obtained.

Conditional expression (5) is a magnification at the telephoto end of the second lens group, and is mainly for favorably performing focusing in the second lens group. By satisfying this condition, the magnification of the second lens unit during zooming from the wide-angle end to the telephoto end is prevented from falling below the unity magnification. As a result, when focusing from an object at infinity to a near object, the second lens unit is always extended in the same direction to obtain good optical performance while reducing aberration fluctuations when focusing with the second lens unit.

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.

(2-1) In the first group, a cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens having convex lens surfaces on both sides are cemented together, and the convex surface is directed toward the object side The second lens unit has a meniscus-shaped positive lens, and the second group has a meniscus-shaped negative lens having a convex surface directed toward the object side, a negative lens having both concave lens surfaces, and a positive lens having both convex lens surfaces.
It also has a negative lens with a concave surface facing the object side.

This makes it possible to reduce aberrations due to zooming and focusing, such as spherical aberration, with a small number of lenses.
It successfully corrects coma and astigmatism, and obtains high optical performance over the entire zoom range.

(2-2) The third group has at least two positive lenses and a negative lens having a concave surface facing the object side.

(2-3) The third group has an aspherical surface whose positive refractive power becomes weaker from the lens center to the lens periphery. As a result, aberration fluctuations due to zooming when widening the angle of view are satisfactorily corrected.

(2-4) 0.2 <f3 / fT <0.3 (6) 1.2 <f3 / fw <1.8 (7) Is to be satisfied.

Conditional expressions (6) and (7) define the ratio of the focal length of the third lens group to the focal length of the entire system at the telephoto end and the wide-angle end, respectively. When the lower limit of conditional expression (6) or (7) is exceeded and the positive refractive power of the third group becomes too strong,
The aberration generated in the third lens unit becomes too large, and it becomes difficult to correct it in a well-balanced manner with other lens units.
Further, when the upper limit of conditional expression (6) or (7) is exceeded and the positive refractive power of the third lens unit becomes too weak, the back focus becomes long and it becomes difficult to make the device compact.

(2-5) The 41st component of the positive refracting power of the fourth group is composed of a positive lens whose both lens surfaces are convex surfaces, and the 42nd component of the positive refracting power is a meniscus with its convex surface facing the object side. The negative lens is a cemented lens in which a positive lens having a convex surface on both sides is cemented, and the 43rd component of the negative refracting power is a negative lens having a concave surface facing the object side. As a result, changes in various aberrations such as coma and spherical aberration due to zooming are corrected in a well-balanced manner.

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.

The aspherical shape has an X axis in the optical axis direction, an H axis in the direction perpendicular to the optical axis, a positive light traveling direction, and R as a paraxial radius of curvature,
When B, C, D, E, F and G are aspherical coefficients,

[0033]

[Equation 1] It is expressed by In addition, " ^ex " represents " ^x10 -x". (Numerical Example 1) F = 28.8 to 189.4 FNO = 1: 4.0 to 5.9 2ω = 73.9 ° to 13.0 ° R 1 = 142.09 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.9 R 2 = 63.74 D 2 = 9.40 N 2 = 1.67000 ν 2 = 57.3 R 3 = -291.56 D 3 = 0.15 R 4 = 44.75 D 4 = 4.80 N 3 = 1.61800 ν 3 = 63.4 R 5 = 86.21 D 5 = variable R 6 = 83.47 D 6 = 1.20 N 4 = 1.72600 ν 4 = 53.6 R 7 = 15.78 D 7 = 5.80 R 8 = -37.17 D 8 = 1.10 N 5 = 1.80400 ν 5 = 46.6 R 9 = 50.15 D 9 = 0.10 R10 = 30.68 D10 = 4.60 N 6 = 1.84666 ν 6 = 23.9 R11 = -35.10 D11 = 0.71 R12 = -26.73 D12 = 1.10 N 7 = 1.88300 ν 7 = 40.8 R13 = 229.33 D13 = Variable R14 = (Aperture) D14 = 0.00 R15 = 22.87 D15 = 3.00 N 8 = 1.51728 ν 8 = 69.6 R16 = 96.76 D16 = 0.12 R17 = 43.13 D17 = 2.00 N 9 = 1.48749 ν 9 = 70.2 R18 = -211.37 D18 = 0.12 R19 = 57.72 D19 = 2.00 N10 = 1.72916 ν10 = 54.7 R20 = 200.80 D20 = 1.70 R21 = -24.05 D21 = 1.20 N11 = 1.80518 ν11 = 25.4 R22 = -69.02 D22 = Variable R23 = 36.28 D23 = 4.00 N12 = 1.51633 ν12 = 64.2 R24 = -23.65 D24 = 0.20 R25 = 221.32 D25 = 1.20 N13 = 1.74400 ν14 = 44.8 R26 = 28.91 D26 = 3.00 N14 = 1.61720 ν14 = 54.0 R27 = -37.70 D27 = 1.33 R28 = -2 4.90 D28 = 1.50 N15 = 1.72600 ν14 = 53.6 R29 = 132.94 D29 = Variable R30 = (Aperture)

[0034]

[Table 1] Aspheric coefficient 27th surface B = 3.998e-05 C = 2.721e-08 D = 1.617e-09
E = -8.901e-12 (Numerical example 2) F = 28.8 to 179.4 FNO = 1: 4.0 to 5.9 2ω = 73.9 ° to 13.8 ° R 1 = 134.03 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.9 R 2 = 62.25 D 2 = 9.40 N 2 = 1.67000 ν 2 = 57.3 R 3 = -288.45 D 3 = 0.15 R 4 = 43.69 D 4 = 4.80 N 3 = 1.61800 ν 3 = 63.4 R 5 = 77.80 D 5 = variable R 6 = 75.35 D 6 = 1.20 N 4 = 1.72600 ν 4 = 53.6 R 7 = 14.81 D 7 = 5.80 R 8 = -33.98 D 8 = 1.10 N 5 = 1.80400 ν 5 = 46.6 R 9 = 60.68 D 9 = 0.10 R10 = 31.14 D10 = 4.60 N 6 = 1.84666 ν 6 = 23.9 R11 = -37.51 D11 = 0.71 R12 = -26.54 D12 = 1.10 N 7 = 1.88 300 ν 7 = 40.8 R13 = 5739.99 D13 = Variable R14 = (Aperture) D14 = 0.00 R15 = 26.22 D15 = 3.00 N 8 = 1.51728 ν 8 = 69.6 R16 = 168.00 D16 = 0.12 R17 = 42.62 D17 = 2.00 N 9 = 1.48749 ν 9 = 70.2 R18 = -329.24 D18 = 0.12 R19 = 49.14 D19 = 2.00 N10 = 1.72916 ν10 = 54.7 R20 = 236.79 D20 = 1.70 R21 = -25.25 D21 = 1.20 N11 = 1.80518 ν11 = 25.4 R22 = -79.40 D22 = Variable R23 = 76.36 D23 = 3.00 N12 = 1.51633 ν12 = 64.2 R24 = -25.17 D24 = 0.20 R25 = 188.45 D25 = 1.20 N13 = 1.74400 ν14 = 44.8 R26 = 22.51 D26 = 4.00 N14 = 1.61720 ν14 = 54.0 R27 = -34.61 D2 7 = 2.23 R28 = -20.45 D28 = 1.50 N15 = 1.72600 ν14 = 53.6 R29 = -98.14 D29 = Variable R30 = (Aperture)

[0035]

[Table 2] Aspheric coefficient 29th surface B = 1.863e-05 C = 6.005e-08 D = -7.620e-10
E = 7.659e-12 (Numerical example 3) F = 28.8 to 195.0 FNO = 1: 4.0 to 6.0 2 ω = 73.9 ° to 12.7 ° R 1 = 133.28 D 1 = 2.00 N 1 = 1.84666 ν 1 = 23.9 R 2 = 62.59 D 2 = 9.40 N 2 = 1.67000 ν 2 = 57.3 R 3 = -290.40 D 3 = 0.15 R 4 = 43.82 D 4 = 4.80 N 3 = 1.61800 ν 3 = 63.4 R 5 = 77.93 D 5 = Variable R 6 = 76.29 D 6 = 1.20 N 4 = 1.72 600 ν 4 = 53.6 R 7 = 14.85 D 7 = 5.80 R 8 = -32.90 D 8 = 1.10 N 5 = 1.80400 ν 5 = 46.6 R 9 = 60.94 D 9 = 0.10 R10 = 32.07 D10 = 4.60 N 6 = 1.84666 ν 6 = 23.9 R11 = -37.66 D11 = 0.71 R12 = -26.95 D12 = 1.10 N 7 = 1.88 300 ν 7 = 40.8 R13 = -1111.58 D13 = Variable R14 = (Aperture) D14 = 0.00 R15 = 25.46 D15 = 2.50 N 8 = 1.51728 ν 8 = 69.6 R16 = 11945.08 D16 = 0.12 R17 = 31.00 D17 = 2.50 N 9 = 1.48749 ν 9 = 70.2 R18 = -136.13 D18 = 1.82 R19 = -25.76 D19 = 1.20 N10 = 1.80518 ν10 = 25.4 R20 = -66.86 D20 = Variable R21 = 79.06 D21 = 3.00 N11 = 1.51633 ν11 = 64.2 R22 = -24.97 D22 = 0.20 R23 = 165.06 D23 = 1.20 N12 = 1.74400 ν12 = 44.8 R24 = 23.29 D24 = 4.00 N13 = 1.61720 ν14 = 54.0 R25 = -40.52 D25 = 2.56 R26 = -21.01 D26 = 1.50 N14 = 1.72600 ν14 = 53.6 R27 = -117.21 D27 = Variable R28 = (Aperture)

[0036]

[Table 3] Aspheric coefficient 15th surface B = -3.788e-06 C = -1.122e-08 D = 5.977e-12 27th surface B = 2.111e-05 C = 6.875e-08 D = -7.973e-10
E = 8.979e-12

[0037]

[Table 4]

[0038]

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 a wide field of view of about 75 degrees, a zoom ratio of about 6 to 7 and a high optical performance over the entire screen by appropriately setting the above. .

[Brief description of drawings]

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

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

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

FIG. 4 is an aberration diagram at a wide-angle end according to Numerical Example 1 of the present invention.

FIG. 5 is an aberration diagram at a telephoto end according to Numerical Example 1 of the present invention.

FIG. 6 is an aberration diagram at a wide-angle end according to Numerical Example 2 of the present invention.

FIG. 7 is an aberration diagram at a telephoto end according to Numerical Example 2 of the present invention.

FIG. 8 is an aberration diagram at a wide-angle end according to Numerical Example 3 of the present invention.

FIG. 9 is an aberration diagram at a telephoto end according to Numerical Example 3 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 (6)

[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, each lens unit is moved toward the object side, the distance between the first and second groups increases, and the distance between the second and third groups decreases. The third lens unit and the fourth lens unit are moved so that the distance between them decreases. The fourth lens unit has a positive refractive power 41st component, a positive refractive power 42nd component, and a negative refractive power It has three components of 43 components, and has an aspherical surface with a shape in which the positive refractive power becomes weaker from the lens center to the lens periphery,
The focal length of the i-th group is fi, the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and fT, and the zoom ratio of the second group is Z.
2 is satisfied: 0.05 <| f2 | / fT <0.09 0.3 <f1 / fT <0.7 0.2 <f4 / fT <0.43 <Z2 <4 A zoom lens featuring. 2. The cemented lens in which a negative meniscus lens having a convex surface facing the object side and a positive lens having a convex surface on both lens surfaces are cemented together, and a meniscus lens having a convex surface facing the object side. The second lens unit has a positive lens, and the second lens unit has a meniscus-shaped 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 concave surface directed to the object side. The zoom lens according to claim 1, further comprising a negative lens. 3. 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. 4. The zoom lens according to claim 1, wherein the third lens unit has an aspherical surface having a shape in which the positive refracting power becomes weaker from the lens center toward the lens periphery. 5. The zoom lens according to claim 1, wherein the condition 0.2 <f3 / fT <0.3 1.2 <f3 / fw <1.8 is satisfied. 6. The 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, each lens unit is moved toward the object side, the distance between the first and second groups increases, and the distance between the second and third groups decreases. The third lens unit and the fourth lens unit are moved so as to reduce the distance between them, and the focus is moved by moving the second lens unit on the optical axis. The focal length of the i-th lens unit is fi, the wide-angle end and the telephoto end. When the focal lengths of the entire system at the end are fw and fT, and the zoom ratio of the second group and the magnification at the telephoto end are Z2 and β2T, respectively, 0.05 <| f2 | / fT <0.090 A zoom lens characterized by satisfying the following condition: 3 <f1 / fT <0.7 0.2 <f4 / fT <0.43 <Z2 <4 | β2T | <1.