GB2080966A - A zoom lens of high vari-focal ratio having negative front lens group - Google Patents

Abstract

The present invention relates to a compact zoom lens with high zoom ratio, having vari-focal range including wide-angle. It is so designed so that the positive rear lens group of the so- called two-group zoom lens, where the front lens group has negative and the rear lens group has positive refractive power, is divided into three components which are positive, negative and positive at least the first and third of which are movable. The spaces between these three components are varied in such manner that the principal point PT-PW of the rear lens group moves more extensively than the movements of the three individual lens components. By such an arrangement of lens components, the movements of individual lens components can be relatively small, despite the high zoom ratio, while variation of aberration due to lens movement can be reduced. In the embodiments (Figs. 3, 5, 7 and 9 not shown) each component comprises at least 2 lenses. <IMAGE>

Description

SPECIFICATION A zoom lens of high vari-focal ratio having negative front lens group The present invention is composed of four lens components of negative, positive, negative and positive from object side, materializing a compact zoom lens system with high vari-focal ratio including wide-angle by improving the moving procedure for lens groups, to be moved for vari-focal purposes.

As a typical example for zoom lens having negative component in front group, two-group zoom lens may be cited. This type of zoom lens offers many advantages; e.g. a relativeiy compact zoom lens system can be composed since this two-group lens has rather simple configuration; wide-angle range can easily be included within the range of its focal length by utilizing arrangement of retro-focus type refractive power since negative lens component is in front position; and also, it has more advantages to take shorter length for focusing since negative lens component is in front position in focal adjustment within wide-angle range.

There are, however, some disadvantages involved in this type of zoom lens. For example, since it has rather simple configuration, the movement of each component becomes more extensive when it is desired to have zoom lens having high vari-focal ratio over twice, causing thereby radical change in aberration due to variation in focal length. Thus, it becomes very difficult to compensate aberration. It is further difficult to compose lens-barrel mechanism having more extensive movements.

The present invention utilizes the advantages inherent in a two-group zoom lens having negative lens component in front position, by improving the configuration of rear lens group and by changing the moving procedure thereof.

The positive rear lens group is divided into three components of the second positive lens component, the third negative lens component and the fourth positive lens component, making a four component composition by adding the first negative lens component, which is the negative lens component of front group. As the total focal length of the whole system is varied from the longest focal length to the shortest focal length, the front lens group is moved toward object side along optical axis.

By moving each component along the optical axis in such manner that the distance between principal point on image side of the second lens component and the principal point on object side of the third lens component is decreased within rear lens group, and that the distance between the principal point on image side of the third lens component and the principal point on object side of the fourth lens component is increased, the principal point on object side of rear lens group is extensively moved from object side to image side. This permits actual movements of each lens component to remain at minimal extent while the movements of rear lens group are efficiently big.Thus, the invention realizes to compose a zoom lens having such high vri-focal ratio including wide-angle as to have never been attained so far by conventional two-group zoom lens, by minimizing aberration change of each lens component due to variation in focal length.

Figs. 1 and 2 are the graphs illustrating loci of movements of each lens component in zoom lens based on the present invention. Fig. 3, 5, 7 and 9 are sectional views for zoom lens as represented in embodiments 1 to 4, respectively. Figs. 4, 6, 8 and 10 show aberration curves of zoom lens as represented in said embodiments 1 to 4, and Fig. 11 shows graphs of actual loci of movements for each lens component of the zoom lens as represented in the above mentioned embodiments.

Fig. 1 is a graph showing loci of movements of each lens component of the zoom lens as realized by the present invention in relation to variation of focal length. In this figure, loci of movements of principal point on object side of rear lens group are represented by P,.... PWT and these loci of movements correspond to the loci, along which the second positive lens component is to move in relation to variation of focal length in case this zoom lens is composed as the ordinary two-group zoom.

If these loci of movements are compared, it is self-evident that the movements of the second, third and fourth lens components, which compose this lens group, are sharply decreased in relation to the movements of principal point on object side of rear lens group.

The following equations can be formed concerning this zoom lens: Suppose that: f : Total foci length of the whole system The The longest focal length of the whole system fw : The shortest length of the whole system fi : Focal length of No. i lens component Ski : Distance from principal point on image side of No. i lens component to principal point on object side of No. i + 1 lens component S = S2 + + Smax : Maximum value of S p : Distance from principal point on image side of the second lens component to object side principal point of rear lens group when total focal length of the whole system is f.

PT : PfT Pw Pfw fR : Total focal length of rear lens group when total focal length of the whole system 1sf.

fRT : The value of fR when f=fT fRW : The value of fR, when f=fw Then,

Also, when total focal length of the whole system is zoomed from the longest focal length fT to the shortest focal length f,,,, the following equation is formed as Pf is steadily in creased:

The portion of this equation down to the second term means that the movements from PT at the longest focal length to Pw at the shortest focal length is linearly interpolated, thus giving Pf at the focal length f. &alpha;, represents the deflection of the linearly interpolated value, and it is a continuous function satisfying the following condition:: O(fW = O(fT = O (iv)

The equation (iv) is naturally formed if f=fT and f=fW are supposed in the equation (iii). The equation (v) is to make up the condition: #P #0 #f by which zooming focal length is changed steadily from fr to fw.

Further, if condition is given, where the distance from image side principal point of the second lens component of rear lens group to object side principal point of the fourth lens component (except principal point space of the third lens component) S = S2 + S3 also changes steadily down from ST to Sw, the configuration of each lens component can be uniquely determined at every focal length.

Also, assuming that the value of S is Sf in case focal length of the whole system is f, and determining Pf by the equation (iii), S2 is obtained as follows: where

This is derived by solving the equation (i) in relation to S2. Further, S3 also can be determined from: S3 = SfS2 and fR is also obtained from the equation (2).

Supposing that the distance from object side principal point of the fourth lens component to image side principal point of rear lens group is P,', this can be obtained by the following equation:

Then, the distance S, from image side principal point of the first lens component to object side principal point of the second lens component and the distance fB from image side principal point of the fourth lens component to the image are determined by the following equations: S, = (1 f,/f) fR Pf + 1 (viii) fB = (1- f/f1) fR + Pf' (ix) In the process of determining the configuration of each lens component, the mode of giving at and S is arbitrary.This may be, however, determined by considering aberration correction and lens-barrel mechanism, and does not deviate from the original aim of the present invention, in which it is asserted that the movement of object side principal point of rear lens group is increased in relation to the movement of each lens component.

The zoom lens system as constituted by the above mentioned requirements should meet the following condition:

This condition is concerned in the movement of object side principal point of rear lens group. If movement goes down beyond lower limit, the effect of principal point movement is weakened and, therefore, zoom lens having high vari-focal ratio cannot be obtained. On the contrary, if it goes up beyond upper limit, the balance may not be kept between refractive power of each lens component in rear lens group, and aberration becomes difficult to correct.

In order to provide sufficient back-focal distance as interchangeable lens for single-lens reflex camera and to arrange lenses in compact composition, the following conditions shall be met: 0.5 fw < fRW < 2 fw (2) -2 2 fw < fi < f= (3) The condition (2) is the requirement, in which sufficient back-focal distance is taken, while total length of lenses is kept comparatively short. It is self-explanatory from the equations (viii) and (ix) that, if total focal length fRW of rear lens group goes down beyond lower limit, sufficient back-focal distance cannot be taken, while, if it goes up beyond upper limit, total length of the lenses becomes too long.

The condition (3) is the requirement to prevent lense diameter becoming too large. If f, becomes smaller than lower limit, image magnification of rear lens group is extremely reduced near the shortest focal length. Since the image extending to margin of picture should be enlarged image on front lens group, effective diameter of front lens group must be extremely enlarged in order to pass sufficient luminous flux. On the contrary, if f, becomes bigger than the upper limit, image magnrnca'tion is extremely increased near the longest focal length. In order to have sufficient aperture ratio, effective diameter of rear lens group must be extremely enlarged.

The above mentioned requirements are met by zoom lens, whose loci of movements are as shown in Fig. 1, and whose actual distribution of refractive power and arrangement are as follows: f1 = -42, f2 = 30, f, = -25, f4 = 40

t P | P - S2 S3 The longest focal length 82.0 4 25.5 9.5 The shortest focal length 28.8 29 11.0 20.5 Here, S and Pf have been determined by the following equation: 3.5 S=31.5+ (f-28.8) 53.2.

25 Pf=29 29(f28.8) 53.2 Also, it is very advantageous, for instance, in designing lens-barrel, to have immovable lens, component among other lens components. By utilizing the fact that the movement of the third lens, component is small, it is contrived that this does not move in relation to the image. The condition for this is: S3 + fob = constant (x) From this condition and from the equation (iii), S2 and S3 are determined.

Fig. 2 shows loci of movements for each component of this zoom lens, whose distribution qf refractive power and whose arrangement are as follows: f, = 41.3 f2 = 26.7 f3 = -22.1 f4 = 37.0

f P 82 I The longest focal length 83.0 T 25.4 j 1 The-shortest focal length 28.8 23.J' 10.2 17 S + fB = 70.14 fRW = 46.07 In the above, fundamental composition of zoom lens based on the present invention has been explained. | To materialise high performance zoom lens, it is needless to say that various aberrations must be satisfactorily corrected.

Normally, negative lens components, which are located on object side froin diaphragm, and positive lens components, which are located on image side from diaphragm, have tendency to produce negative distortion, while positive lens component located on object side -from diaphragm and negative lens component located on image side from diaphragm have tendency to produce positive distortion. In the four-component zoom lens based on the present invention, if total focal length of the whole system is on the long focal point side with diaphragm fixed on the third negative lens component, the first negative lens component and the fourth positive lens component, which have tendency to produce negative distortion, come closer to diaphragm, and the second positive lens component, which have tendency to produce positive distortion, goes away from diaphragm.On the contrary, if total focal length of the whole system is on the short focal point side, the second positive lens component having tendency to produce positive distortion comes closer to diaphragm, while the first negative Ie,s component and the fourth positive lens component having tendency to produce negative distortion go away from diaphragm. In consequence, the so-called zoom lens type phenomena are resulted, where positive distortion is apt to be generated on long focal point side, while negative distortion is apt to be generated on short focal point side.Consequently, it is necessary to include at least one positive singlet in the first negative lens component, and to include at least one positive doublet, whose cemented surface is the divergent surface with its convex side facing toward object, in the fourth positive lens component.

By using positive singlet, particularly its surface facing toward image, of the first negative lens component, and by using divergent cemented surface in the fourth positive lens component to produce positive distortion, the generation of the above mentioned distortion in the whole system can be suppressed. It is more effective for the correction of negative distortion to arrange positive lens in the first lens component on object side of the first negative lens component so that luminous flux of marginal height passes the route most distant from optical axis.

It is further desirable to satisfy the following conditions for correcting various aberrations for the zoom lens based on the present invention: Suppose that: f, 1 : Focal length of positive singlet as arranged on object side of the first lens component Abbe's number for the above positive singlet : : Refractive index of negative lens, which comprises positive cemented doublet in the second positive lens component.

n2p : Refractive index of positive lens in the above cemented doublet.

k2c : Refractive power of the above cemented surface.

n4N : Refractive index of negative singlet, which comprises positive lens including cemented divergent surface in the fourth positive lens component.

: : Refractive index of positive singlet, which comprises the above positive lens.

k4c : Refractive power of the above cemented surface.

Then, 4 If,l < f" (5) 40 < L'i.i (6) 0.08 < n,, -- n,, (7)

0.15 < n,, -- n,, (9)

The shorter the focal length of positive singlet arranged on object side of the first negative lens component, the more advantageous it is to correct negative distortion generated in the first lens component as a whole. If it is made shorter beyond lower limit of the condition (5), effective diameter of lens must be enlarged, thus causing more frequent generation of coma around view angle on the shortest focal length side.

Also, if Abbe's number for glass material, of which this positive singlet is made, is decreased beyond lower limit of the condition (6), the extent of correction for negative distortion generated on the shortest focal length side varies widely depending on wavelength of light, thus causing extensive generation of chromatic aberration of magnification.

The second positive lens component is of strongly convergent type, and is particularly concerned with generation of spherical aberration on the longest focal length side. The conditions (7) and (8) represent the requirements, where cemented surface of positive cemented doublet as arranged in this lens group for achromatic purpose is utilized for adjusting undercorrected spherical aberration generated on the longest focal length side.

If the difference in refractive indices is reduced beyond lower limit of the condition (7), corrective effect of spherical aberration fades away and is no more capable to adjust undercorrected spherical aberration on the longest focal length side. If refractive power of cemented surface is reduced beyond lower limit of the condition (8), corrective effect on spherical aberration fades away. On the contrary, if it is increased beyond upper limit, strong comatic flare is generated against off-axial luminous flux on the longest focal length side.

The positive cemented doublet, whose cemented surface arranged in the fourth positive lens component is divergent surface with convex side facing toward object, is particularly important for correcting negative distortion on the shortest focal length side.

The condition (9) expresses the requirements, by which cemented surface can correct negative distortion as divergent surface. If the difference in refractive powers is reduced beyond lower limit, the effect of correcting distortion is weakened, and negative distortion is increased as a whole, If refractive power of this cemented surface is reduced beyond lower limit of the condition (10), corrective effect of negative distortion is weakened. On the contrary, if it goes up beyond the upper limit, it is effective for correcting negative distortion as generated on the shortest focal length side, while undercorrected comatic flare is generated extensively around picture.

The embodiments, which satisfy all the requirements mentioned above, are now to be explained in detail as follows: Embodiment 1 Focal length 28.9~ 82.9 F number 4.0 View angle: 2w = 784 ~28.8 .

d # d n vd 1 327.610 4.20 1.51112 60.9 2 the first lens -432.727 0.20 3 component 106.970 1.80 1.71300 53.8 4 28.401 7.90 5 -3633.590 1.30 1.71300 53.8 6 46.175 2.00 7 37.247 3.78 1.80518 25.4 8 # 59.101 variable 9 the second lens 44.650 1.20 1.80518 25.4 10 component 23.080 6.50 1.62299 58.2 11 -88.000 0.15 12 34.300 4.84 1.62299 58.2 13 560.939 variable 14 the third lens # 125.177 4.30 1.74077 27.8 15 component -19.834 1.00 1.77250 49.6 16 37.975 2.40 17 -34.610 1.00 1.62299 58.2 18 95.985 variable 19 # -399.453 3.50 1.71300 53.8 20 the fourth lens -35.834 0.20 21 component -377.096 1.20 1.80518 25.4 22 . # 31.249 7.90 23 # -77.458 0.20 24 68.148 3.50 1.62299 58.2 25 -127.416

f=28.9 | f=49.4 | f=82.9 da 39.964. 15.295 2.600 d13 2.500 8.791 16.501 d18 1.347 6.919 1.300 fB 51.137 58.316 70.844 f1=-42.393, f2=30.160, f3=-24.519, f4=37.871 Embodiment 2 Focal length f - 28.8~82.0 F number 4.0 View angle: 2w - 762 ~28.6

r d n #d 1 150.065 4.50 1.51112 60.5 2 -650.652 0.20 3 the first lens 96.636 1.80 1.71300 53.8 4 component # 30.615 7.50 5 -222.909 1.30 1.71300 53.8 6 40.837 3.78 1.80518 25.4 7 . 85.678 variable 8, 74.900 1.20 1.80518 25.4 9 the second lens 24.737 6.20 1.71300 53.8 10 component # -96.547 0.15 11 27.836 4;83 1.62299 58.2 12 -2806.470 variable 13 the third lens # 173.638 3.60 1.74077 27.8 14 component -15.474 1.00 1.77250 49.6 15 32.917 2.00 16 -34.664 1.00 1.62299 58.2 17 # 137.820' variable 18 . -117.065 6.00 1.71300' 53.8 19 -14.995 t.00 1.80518 25.4' 20 the fourth lens -27.225 0.15 21 component # 102.005 1.00 1.80610 40.9 22 25.090 7.00 1.62299 58.2 23 -150.354 0.15 24 44.120 4.00 1.62299 58.2 25 70.122

f=28.8 | f=49.4 | f=82.0 d, 39.000 14::300 1.500' d12 2.500 7.653 17.700 di7 9.700 6.096 0.800 fB 45.977 53.111 55.109 f1=-44,218, f2=37.788, f3=-22.570, f4=35.395 Embodiment 3 Focal length f - 28.9 ~82.1 View angle: 2w =762 ~28.6

d . d n vd 1 the first lens 441.740 4.00 1.51112 60.5 2 component -163.306 0.20 3 136.090 1.60 1.71300 53.8 4 # 27.773 6.00 5 -76.195 1.30 1.71300 53.8 6 52.285 3.50 1.80518 25.4 7 the second lens 249.718 variable 8 component . 97.266 1.20 1.80518 25.4 9 25.257 5.00 1.71300 53.8 10 # -59.196 0.15 11 26.598 4.00 1.62299 58.2 12 # -965.869 variable 13 the third lens -8487.457 4.00 1.74077 27.8 14 component -15.546 1.00 1.77250 49.6 15 39.234 2.92 16 -43.921 1.00 1.62299 58.2 17 88.761 variable 18 -123.163 6.00 1.71300 53.8 19 the fourth lens -17.182 1.00 1.80518 25.4 20 component -31.545 0.15 21 # 64.678 1.00 1.80610 40.9 22 23.282 9.00 1.622299 58.2 23 -38.807

f=28.9 | f=48.0 | f=82.1 d7 31.000 12.461 1.500 d12 2,500 7.218 16.000' d17 12.437 7.415 1.000 fB 48.823 58.607 63.736 f1=-36.053, f2=25.031, f3=-22.426, f4=38.306 Embodiment 4 Focal length f = 28.8~83.0 View angle: w - 768 ~28.1

r d n #d 1 the first lens 264.355 4.50 1.51112 60.5 2 component -307.829 0.20 3 119.368 1.60 1.71300 53.8 4 33.618 7.50 5 -140.505 1.30 1.71300 53.8 6 39.874 4.00 1.80518 25.4 7 91.t76 variable 8 the second lens 99.618 1.20 1.80518 25.4 9 component 25.493 6.20 1.71300 53.8 10 # -63.847 0.15 11 27.206 4.80 1.62299 58.2 12 1445.097 variable 13 175.320 3.60 1.74077 27.8 14 the third lens -15.942 1.00' 1.77250 49.6 15 component - 35.005 2.00 1.62299 58.2' 16 -32.230 1.00 1.62299 53.8 17 118.667 variable 18 -246.711 7.50 1.71300 53.8 19 -14.913 1.00 | 1.80518 25.4 20 -27.371 0.15 21 the fourth lens 79.521 1.00 1.75700 47.9 22 component - 23.502 | 7.00 | 1.51633 64.1 23 -291.431 0.15 24 50; ;284 4.00 1.51633 64.1 25 104.292

f=28.8 | f=51.0 | f=83.0 d7 38.883 13.628 1.500 d12 2.500 9.256 17.700 d17 10.000 6.000 1.000 46.001 | 49.963 | 55.008 f1=-41,3 f2=25.7, f2=-22.1, f4=37.0

Claims (10)

1. A zoom lens, comprising four components which are a negative first lens component, a positive second lens component, a negative third lens component and a positive fourth lens component from the object side, said first lens component being arranged in the front lens group, and said second component and said forth component being arranged in the rear lens group, said front lens group being movable towards the object side, and said rear lens group being substantially movable towards the image as the total focal length of the whole lens system is varied from the longest focal length to the shortest focal length, and wherein i) within the rear lens group, each lens component is moved in such a manner that the distance between the principal point of said second lens component and the object side principal point of said third lens component is decreased, and that the distance between the image side principal point of said third lens component and the object side principal point of said fourth component is increased, and ii) fT : the longest total focal length of the whole lens system, fW : the shortest total focal length of the whole lens system, fRW : total focal length of rear lens group at the shortest focal length, PT : Distance from image side principal point of the second lens component to object side principal point of rear lens group at the longest focal length.

PW : Said distance between principal points at the shortest focal length.

Smax : Maximum value for S, which is a sum of the distance from image side principal point of the lens component to object side principal point of the third lens component, and of the distance from image side principal point of the third lens component to object side principal point of the fourth lens component, the zoom lens having high vari-focal ratio with a negative component in front group, and satisfying the condition:

2. A zoom lens according to Claim 1, satisfying the conditions: 0.5fW < fRW < 2fW - 2f < f1 < - f, where f,: Focal length of the first lens component.

3. A zoom lens according to Claim 2, including at least one positive singlet in the first negative lens component, including at least one positive doublet, whose cemented surface also being divergent surface with convex side facing toward object, in the fourth positive lens component.

4. A zoom lens according to Claim 2, with said negative third lens component fixed.

5. A zoom lens according to Claim 3 or Claim 4, satisfying the conditions: 4If1 < f1.1 40 < v1,1 0.08 < n2N-n2P 0.08/f3 < |k2c| < 0.30/f2 0.15 < n4N-n4P 0.2/f4 < |k4c| < 0.5/f4 where: 11 : Focal length of positive singlet as arranged on object side of said first lens component.

p1,1 Abbe's number of said positive singlet.

: : Refractive index of negative lens, comprising positive cemented doublet in said second positive lens component.

n2p : Refractive index of positive lens in said cemented doublet.

k2C : Refractive power of said cemented surface.

n4N : Refractive index of negative lens, comprising positive lens including cemented divergent surface in said fourth positive lens component.

n4p Refractive index of positive singlet, which comprises said positive lens.

k4c : Refractive power of said cemented surface.

6. A zoom lens according to Claim 5, as specified by the following data: Embodiment 1 Focal length f P 28.9~82.9, F number 4.0 View angle:2w = 764 ~28.8

# r n vd 1 the first lens 327.610 4.20 1.51112 60.5 2 component -432.727 0.20 3 106.970 1.60 1.71300 53.8 4 # 28.401

7.50 5 -3633.590 1.30 1.71300 53.8 6 46.175 2.00 7 37.247 3.78 1.80518 25.4 8 | #| 59.101 | variable 9 the second lens 44.650 1.20 1.80518 25.4 10 component 23.080 6.50 1.62299 58.2 11 # -88.000 0.15 12 34.300 4.84 1.62299 58.2 13 580.939 variable 14 125.177 4.30 1.74077 27.8 15 the third lens | -19.834 1.00 1.77250 49.6 16 component # 37.975 2.40 17 -34.610 1.00 1.62299 58.2 18 # 95.965 variable 19 , -399.453 3.90 1.71300 53.8 20 -35.834 0.20 21 the fourth lens -377.096 1.20 1.80518 25.4 22 component # 31.249 7.60 1.61633 64.1 23 -77.458 0.20 24 68.148 3.50 1.02299 58.2 25 X -127.416

f=28.9 | f=49.4 | f=82.9 d8 39.964 15.295 2.600 d13 2.500 8.791 16.501 d18 11.347 6.919 1.300 51.137 | 58.316 | 70.844 f1=-42.393, f2=30.160, f3=24.519, f4=37.871 7.A zoom lens according to Claim 5, as specified by the following data: Embodiment 2 Focal length f = 28.8N 82.0 F number 4;0 View angle: 1w = 762 ~28.6

r d n vd 1 the first lens # 150.065 4.50 1.51112 60.5 2 component -650.652 0.20 3 96.636 1.60 1.71300 53.8 4 # 30.615 7.50 5 -222.909 1.30 1.71300 53.8 6 40;;837 3.78 1.80518 25.4 7 # 85.678 variable 8 74.900 1.20 1.80518 25.4 9 the second lens 24.737 6.20 1.71300 53.8 10 component 1 -96.547 0.15 11 27.836 4.83 1.62299 58.2 12 -2806.470 variable 13 173.638 3.60 1.74077 27.8 14 the third lens -15.474 1.00' 1.77250 49.0 15 component | 32.917 2.00' 16 | | -34,684 | 1.00 | 1.62299 | 58.2 17 # 137.820 variable 18 -117.065 6.00' 1.71300 53.8 19 -14.995 1.00 1.80518 25.4 20 the fourth lens -27.225 0.15 21 component 102.005 1.00 1.80610 40.9 22 # 25.090 7.00 1.62299 58.2 23 -150.354 0.15 24 44.120 4.00 1.62299 58.2 25 | #| 70.122

f=28.8 | f=49.4 | f=82.0 d7 39.000 14.300 1.500 d12 2.500 7.653 17.700 d,7 9.700' 6.096 0.600 45.977 | 53.111 | 55.109 f1=-44.218, f2=27.788, f3=-22.570, f4=35.395

8. A zoom lens according to Claim 5, as specified by the following data: Embodiment 3 Focal length f hf = 28.9~82.1 View angle: 2w 2w = 762 ~28.6

r d n vd 1 the first lens 441.740 4.00 1.51112 60.5 2 component -163.306 0.20 3 136.090 1.60 1.71300 53.8 4 # 27.773 6.00 5 -76. 195 1.30 1.71300 53.8 6 52.285 3.g0 1.80518 25.4 7 249.718 variable 8 97.266 1.20 1.80518 25.4 9 the second lens | 25.257 5.00 1.71300 53.8 10 component # -59.196 0.15 11 26.598 4.00 1.62299 58.2 12 -965.869 variable 13 # -8487.457 4.00 1.74077 27.8 14 the third lens -15.546 1.00 1.77250 49.6 15 component 39.234 2.92 16 -43.921 1.00 1.62299 58.2 17 88.761 variable 18 -123.163 6.00 1.71300 53.8 19 -17.162 1.00 1.80518 25.4 20 the fourth lens -31.545 0.15 21 component 64.678 1.00 1.80610 40.9 22 23.383

9.00 1.62299 58.2 23 -88.807

f=28.9 | f=48.0 | f=82.1 d7 31.000 12.461 1.500 d12 2.500 7.218 16.000 d17 12.437 7.415 1.000 48.823 | 56.607 | 63.736 f1=-36.053 f2=25.031, f3=-22.426, f4=38.306 9.A zoom lens according to Claim 5, as specified by the following data: Embodiment 4 Focal length f = 28.8 View angle: w - # W = 768 ~28.1

r d n vd 1 the first lens 264.355 4.50 1.51112 60.5 2 component -307.829 0.20 3 119.368 1.60 1.71300 53.8 4 # 33.618 7.50 5 -140.505 1.30 1.71300 53.8 6 39.874 4.00 1.80518 25.4 7 91.178 variable 8 99.618 1.20 1.80518 25.4 9 the second lens 25.493 6.20 1.71300 53.8 10 component # -63.847 0.15 11 26.206 4.80 1.62299 58.2 12 1445.097 variable 13 175.320 3.60 1.74077 27.8 14 the third lens -15.942 1.00 1.77250 49.6 15 component # 35.005 2.00 16 -32.230 1.00 1.62299 58.2 17 118.667 variable 18 -248.711 7.50 1.71300 53.8 19 -14.913 1.00 1.80518 25.4 20 the fourth lens -27.371 0.15 21 component 79.521 1.00 1.75700 47.9 22 # 23.5032 7.00 1.51633 64.1 23 -291.431 0.15 24 50.284 4.00 1.51633 64.1 25 104.292

f=28.8 f=51.0 f=83.0 d7 38.883 13.628 1.500 d12 2.500 9.258 17.700 d17

10.000 6.000 1.000 fB 46.001 49.963 55.006 f1=-41.3, f2=26.7, f3=22.1, f4=37.0