GB2033605A

GB2033605A - Zoom lenses having two lens groups

Info

Publication number: GB2033605A
Application number: GB7931532A
Authority: GB
Original assignee: Vivitar Corp
Current assignee: Vivitar Corp
Priority date: 1978-09-11
Filing date: 1979-09-11
Publication date: 1980-05-21

Abstract

A two-group zoom lens having a negative front group G1 and a positive rear group G2 which move axially relatively to vary the equivalent focal length. The ratio of the absolute optical power of the front group to the optical power of the rear group is less than .6. The lens may comprise as few as seven elements, is compact and has a large relative aperture. The equivalent focal length range of the lens may subtend the diagonal of its image frame with a field of view of 60 degrees. <IMAGE>

Description

SPECIFICATION Improvements in zoom lenses This invention relates to zoom lenses.

Variable focal length lenses comprising two groups with the front group negative have usually had a ratio of front vertex distance (FVD) to maximum equivalent focal length (EFL) which is quite large, on the order of 1:8. If maximum speed of the lens has become greater than f/4.0, the number of the elements required for the lens increases, therefore, increasing the size of the lens and the cost of manufacture. The lenses became larger than desirable for use as a substituted for the normal camera lens which has an EFL of about 50 to 55mm for the 35mm film format.

The present invention consists in a zoom lens comprising from the object end a first negative group and a second positive group, said groups being movable axially of the lens to vary the equivalent focal length of the lens, and 'K1' < 6 K2 where /K1 is the absolute optical power of the first group, and K2 is the optical power of the second group.

Suitably, a zoom lens according to the invention spans the fixed focal length of the so-called normal camera lens, is compact and has relative apertures as fast as f,2.8. The lens may have a zoom ratio of about two to one which may span the diagonal of the image plane of the lens.

One lens embodying the invention comprises a zoom lens having a negative first group and a positive second group. The ratio of the absolute powers of these groups is maintained within given limits to maintain the compactness of the lens and the ratio of the surfaces of the first element of the first group is so selected as to obtain optimum correction of distortion and spherical aberration. The first group may comprise three air-spaced components in which the first component is a positive element and the second component is a strong negative element followed by another positive component. The configuration of the first group results in reduced higher order of astigmatism, while enabling a minimum size to be maintained.

In zooming, the two groups move axially at different rates and the front vertex distance of the lens increases from the higher EFL to the lower EFL. The lens is focused by axial movement of the first group. For simplicity of construction, the aperture stop of the lenses may be arranged for movement with the rear group, in which case the relative aperture may vary between ranges off/.28 and a somewhat slower f/3.8.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which Figures 1-3 are diagrammatic side views of lenses embodying the invention in the longer EFL position; Figures la, 2a and 3a are diagrammatic side elevations of the lenses of Figures 1,2 and 3, respectively, in the shorter EFL position; Figure 4 is a diagram of the first group of a lens embodying the invention having a second group constructed similar to that of Figures 1 and 1a; and Figures 5, 6 and 7 are diagrammatic side views of other lenses embodying the invention.

Lenses embodying the invention have about a 2:1 zoom ratio and subtend angles from about the so-called wide angle range to what may be termed long focus. The term wide angle may be defined as an equivalent focal length (EFL) which is below the diagonal of the image frame. Generally, lens embodying the invention will have an EFL range within the range of 35-9Omm as scaled to an image frame of 24 x 36mm.

A lens embodying the invention has two zooming groups, and the front vertex distance (FVD) will increase as the EFL is varied downward. Due to the unique construction, a lens embodying the invention may have as few as seven air-spaced elements.

The lens is constructed with a front negative group G1 and a rear positive group G2. The front group may comprise three air-spaced elements as shown in Figures 1 and 3 or may comprise one or more doublets as shown in Figure 2 and Table IV.

In all cases, the following parameters are met to achieve the objectives of the invention.

.6 > /K,//K2 > .3 and Ro/Rg > 1 where /K1/ is the absolute optical power of the EFL of the front group, K2 is the optical power of the second group, Ro is the object side radius of the first lens component, and R1 is the image side radius of the first lens component (which may be a doublet).

Lenses embodying the invention have a ratio of minimum front vertex distance (FVD) to maximum EFL less than one to one and a half, and may have as few as seven elements. This permits the lens to be easily stored and carried in the long EFL position.

The relationship of the radii of the surfaces of the first element is important in this lens for correction of distortion and spherical aberration. The ratio of the absolute powers of the groups to a maximum of .6 and preferably above .4 is necessary to maintain compactness of the lens.

In the drawings and Tables, the lens elements are indicated by L from the object end progressively followed by an arabic numeral. The element surfaces are indicated by S followed by an arabic numeral from the object end to the image end, the variable space during zooming is indicated by Z. The two lens groups are designated G1 and G2 and the focal or film plane is FP.

A first embodiment of the invention as shown in Figures 1 and 1a in the long focal length position, and the short focal length positions, respectively, comprises a front negative group G1 and a rear positive group G2.

Group G1 comprises a first positive element L1, a second bi-concave element L2 and a positive meniscus L3 convex to the object. Group G2 comprises from the object end a bi-convex element L2, a positive meniscus L3 convex to the object, a relativelv thick bi-concave negative element L6, a positive meniscus concave to the object L7 and a final positive element L8. The lens of Figures 1 and 1a is defined hereinafter in Table I.

Figures 2 and 2a exemplify another form of the invention comprising ten lens elements and utilizing three doublets. Group G1 comprises doublets L1, L2 and L3, L4, the first doublet is a bi-convex element L1 and a bi-concave element L2. The second doublet is a negative meniscus L3 and a positive meniscus L4. Group G2 comprises a bi-convex doublet L5, L6, a positive element L7 convex to the object, the bi-concave element L8, the negative meniscus L9 and a bi-concave element L1 0. The lens of Figures 2 and 2a is defined in Table II.

In a third embodiment of the invention shown in Figures 3 and 3a, only seven elements are utilized. Group G1 comprises elements L1, L2 and L3 having the configuration shown in Figure 1. Group G2 comprises a bi-convex element L4, a positive meniscus L5 convex to the object, a relatively thick bi-concave element and a positive meniscus concave to the object. The lens of Figures 3 and 3a is described in Table Ill.

Figure 4 shows another embodiment of the invention where the first group G1 includes four elements L1, L2, L3 and L4, where elements L3 and L4 define a positive doublet. The second group of this lens has the same elemental construction as shown in Figure 1. The lens of Figure 4 is defined in Table IV.

Figures 5,6 and 7 show another eight element air-spaced lenses in the shorter EFL position and are defined, respectively, in Tables V, Vl and VII.

In Tables l-VII, the data is given to unity focal length.

TABLE I Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 plano L1 0.0833 1.673 32.2 S2 -3.4545 0.0056 S3 -9.3319 L2 0.0556 1.834 37.3 S4 0.7969 0.2181 S5 1.0219 L3 0.0917 1.847 23.8 S6 1.9400 1.2044-0.0278 S7 0.9601 L4 0.1083 1.713 53.9 S8 -4.4059 0.0472 Aperture 0.0278 S9 0.6818 L5 0.0833 1.720 43.9 S10 1.9798 0.0319 S11 -4.0809 L6 0.2278 1.847 23.8 S12 0.5556 0.0731 S13 -1.8539 L7 0.0556 1.806 40.7 S14 -0.8966 0.0056 S15 plano L8 0.0500 1.847 23.8 S16 -4.0300 EFL = 1.0 - 1.89 f/No. = 2.8 - 3.8 FVD = 3.5 - 2.81 FVD Min ~ F1 =2.15 F2=1.16 /F1/F2/=1.85 EFL -1.49 Semi-field angles 31 degrees to 17.6 degrees.

TABLE II Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 2.8645 L1 0.0744 1.487 40.7 S2 -3.2193 L2 0.03911 1.819 34.4 S3 0.6523 0.0657 S4 0.9003 L3 0.0434 1.487 70.4 S5 0.5522 L4 0.1271 1.744 27.1 S6 2.2504 1.1253-0.0428 Aperture 0.0217 S7 0.8409 L5 0.1613 1.734 51.7 S8 -0.7386 L6 0.0391 1.823 24.4 S9 -1.8545 0.0043 S10 0.5029 L7 0.1547 1.582 61.9 S11 3.7461 0.0226 S12 -2.853 L8 0.0466 1.730 37.3 S13 0.7287 0.0335 S14 4.1884 L9 0.0391 1.804 46.5 S15 0.4904 0.0480 S16 9.8605 L10 0.0675 1.592 38.6 S17 -0.8015 EFL= 1.0-1.913 fiNo. = 3.5 FVD = 3.04 - 2.39 FVD Min F1 = -2.2 F2 = 1.03 'F,/F2! = 2.14 FVD Min 1 25 Semi-field angles 25.2 degrees to 13.8 degrees.

TABLE Ill Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 11.8935 L1 0.0798 1.838 31.0 S2 -3.8378 0.0056 S3 -6.5885 L2 0.0694 1.834 37.3 S4 0.7527 0.1911 S5 0.9421 L3 0.0907 1.847 23.8 S6 1.6893 1.2104-0.0278 S7 0.8562 L4 0.1078 1.713 53.9 S8 -4.091 0.0667 Aperture 0.0278 S9 0.8246 L5 0.0758 1.776 43.1 S10 2.5812 0.0347 S11 -1.8940 L6 0.1971 1.847 23.8 S12 0.6235 0.1106 S13 -5.1768 L7 0.0703 1.837 31.8 514 -0.891 EFL= 1.0-1.89 f/No. = 2.8 - 3.8 FVD = 3.5 - 2.81 FVD =2.14 F2 = 1.17 /F1/F2/=1.83 Min F1=-2.14 F2=1.17 /F1/F2/=1.83 EFL =1.49 Semi-field angles 31 degrees to 17.6 degrees.

TABLE IV Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 4.2729 L1 0.1206 1.556 52.7 S2 -1.5780 0.0262 S3 -1.5587 L2 0.0435 1.822 32.8 S4 0.6294 0.0392 S5 0.7856 L3 0.0435 1.487 70.4 S6 0.5727 L4 0.1136 1.817 24.6 S7 2.2725 1.1099-0.0412 Aperture 0.0217 S8 0.9014 L5 0.1585 1.726 52.5 S9 -0.7056 L6 0.0391 1.812 24.7 S10 -1.6944 0.0043 S11 0.4907 L7 0.1680 1.508 68.0 S12 3.2951 0.0183 S13 -4.8528 L8 0.0466 1.640 34.6 S14 0.9599 0.0325 S15 -5.3715 L9 0.0391 1.744 44.8 S16 0.4732 0.0479 S17 6.7733 L10 0.0675 1.633 34.0 S18 -0.8615 EFL= 1.0-1.913 f No. = 3.5 FVD = 3.04 - 2.39 FVD Min Fa = 2.22 F2 = 1.01 IFaIF2/= 2.2 EFLMaX Semi-field angles 25.2 degrees to 13. 8 degrees.

TABLE V Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 -4.9227 L1 0.0698 1.717 29.5 S2 -2.6979 0.0051 S3 -8.5570 L2 0.0641 1.834 37.3 S4 0.8838 0.1752 S5 1.1231 L3 0.1198 1.785 25.7 S6 3.1379 1.5304-0.0256 S7 0.9562 L4 0.0982 1.640 60.2 S8 -10.2845 0.0051 S9 0.8053 L5 0.0662 1.670 57.3 S10 1.3796 0.0080 S11 0.8356 L6 0.0862 1.589 61.3 S12 2.1683 0.0423 Aperture 0.0290 S13 -9.2343 L7 0.1759 1.847 23.8 S14 0.5054 0.0990 S15 -46.3803 L8 0.598 S15 -1.2826 EFL = 1.0 - 2.0 F/No. = 2.8 - 3.8 FVD = 3.7 - 2.69 FVD Min F1 = -2.48 F2= 1.21 /F,/F21= 2.05 EFLMax Semi-field angles 29 degrees to 15.5 degrees.

TABLE VI Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 35.5093 L1 0.0814 1.722 28.3 S2 -3.8670 0.0056 S3 -17.7329 L2 0.0694 1.834 36.4 S4 0.7520 0.1838 S5 0.9353 L3 0.0972 1.847 23.8 S6 1.6898 1.2116-0.0278 S7 0.8892 L4 0.972 1.713 53.9 S8 -8.0494 0.0764 Aperture 0.0278 S9 0.7610 L5 0.0987 1.737 48.9 S10 2.5559 0.0313 S11 -2.3994 L6 0.0867 1.833 24.1 S12 1.8557 0.0174 S13 1.9095 L7 0.0500 1.833 24.1 S14 0.6181 0.0986 S15 -9.9100 L8 0.0725 1.838 31.4 S16 -0.9605 EFL= 1.0-1.89 f/No. = 2.8 - 3.8 FVD = 3.5 - 2.81 FVD Min F1 = -2.14 F2 = 1.18 F1/F2/ = 1.81 EFL Max = 1.49 Semi-field angles 31 degrees to 17.6 degrees.

TABLE VII Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 plano L1 0.0801 1.728 28.3 S2 -3.5813 0.0056 S3 -9.9768 L2 0.0556 1.834 37.3 S4 0.7872 0.2140 S5 1.0039 L3 0.0887 1.847 23.8 S6 1.8669 1.2087-0.0278 S7 0.9098 L4 0.1073 1.713 53.9 S8 -4.9155 0.0599 Aperture 0.0278 S9 0.6694 L5 0.0820 1.720 50.3 S10 1.8841 0.0330 S11 -3.5770 L6 S11 -3.5770 0.1900 1.847 23.8 S12 0.5569 0.0684 S13 -1.9104 L7 0.0528 1.834 37.3 S14 -1.1170 0.0056 S15 -2.7039 L8 S15 2.7039 0.0562 1.847 23.8 S16 -1.2116 EFL = 1.0 - 1.89 f/No. = 2.8 - 3.8 FVD = 3.5 - 2.81 FVD Min Fa = -2.14 F2 = 1.17 /F,/F21= 1.83 FVD Min 1 49 Semi-field angles 31 degrees to 17.6 degrees.

Table VIII sets forth various parameters of the lenses of Tables l-VII.

TABLE VIII K1 K2 /K1/K2/ Ro/RI Table I .0047 .0086 .55 .plano Table II .0045 .0097 .46 4.39 Table lil .0047 .0085 .55 3.10 Table IV .0045 .0099 .45 2.71 Table V .0040 .0820 .48 1.82 Table Vl .0047 .0085 .55 9.18 Table VII .0047 .0085 .55 .piano It may thus be seen that the objects of the invention set forth as well as those made apparent from the foregoing description are efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure, modification to the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments of the invention and modifications to the disclosed embodiments which do not depart from the spirit and scope of the invention.

Claims

1. A zoom lens comprising from the object end a first negative group and a second positive group, said groups being movable axially of the lens to vary the equivalent focal length of the lens, and /K/ < .6 K2 < .6 where /K, is the absolute optical power of the first group, and K, is the optical power of the second group.

2. A zoom lens according to claim 1 where the first group consists of a first positive element, a second bi-concave element and a positive meniscus concave to the object.

3. A lens according to claim 1 where said front group consists of a first negative doublet concave to the image, and a second positive doublet concave to the object.

4. A lens according to claim 1 where said first group consists of a bi-convex element, a bi-concave element, and a positive doublet in the form of a meniscus convex to the object.

5. A lens according to claim 1 where: Ro > 1 R1 where Ro is the radius of the object side surface of the first element of said first group, and R1 is the image side radius of the first element of said first group.

6. A lens according to claim 1 where: Ro > 1 R1 where Ro is the radius of the object side surface of the first doublet of said first group, and R1 is the image side radius of the first doublet of said first group.

7. A lens according to claim 1 where the second group comprises five elements, a first positive element, a second element, a third negative element, a fourth meniscus concave to the object, and a fifth positive element.

8. A lens according to claim 1 where the second group comprises four elements, a first bi-convex element, a second positive meniscus convex to the object, a third bi-concave member, and fourth positive element.

9. The lens of claim 7 where the first positive element is a bi-convex doublet.

10. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 plano L1 0.0833 1.673 32.2 S2 -3.4545 0.0056 S3 -9.3319 L2 0.0556 1.834 37.3 S4 0.7969 0.2181 S5 1.0219 L3 0.0917 1.847 23.8 S6 1.9400

1.2044-0.0278 S7 0.9601 L4 0.1083 1.713 53.9 S8 -4.4059 0.0472 Aperture 0.0278 S9 0.6818 L5 0.0833 1.720 43.9 S10 1.9798 0.0319 S11 -4.0809 L6 0.2278 1.847 23.8 S12 0.5556 0.0731 S13 -1.8539 L7 0.0556 1.806 40.7 S14 -0.8966 0.0056 S15 plano L8 0.0500 1.847 23.8 S16 -4.0300 EFL= 1.0 - 189 f/No. = 2.8 - 3.8 FVD Min FVD = 3.5 - 2.81 F1=-2.15 Up = 1.16 /F1/F2/=1.85 EFLMax =1.49 where the L1-L8 are lens elements progressively from the object to the image end; S1-S16 are the surfaces of the elements L1-L8; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens; F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

11. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 2.8645 L1 0.0744 1.487 40.7 S2 -3.2193 L2 0.03911 1.819 34.4 S3 0.6523 0.0657 S4 0.9003 L3 0.0434 1.487 70.4 S5 0.5522 L4 0.1271 1.744 27.1 S6 2.2504

1.1253-0.0428 Aperture 0.0217 S7 0.8409 L5 0.1613 1.734 51.7 S8 -0.7386 L6 0.0391 1.823 24.4 S9 -1.8545 0.0043 S10 0.5029 L7 0.1547 1.582 61.9 S11 3.7461 0.0226 S12 -2.853 L8 0.0466 1.730 37.3 S13 0.7287 0.0335 S14 4.1884 L9 0.0391 1.804 46.5 S15 0.4904 0.0480 S16 9.8605 L10 0.0675 1.592 38.6 S17 -0.8015 EFL= 1.0-1.913 f/No. = 3.5 FVD = 3.04 - 2.39 F1 = -2.2 F2 = 1.03 /F1/F2. =52.72.14 FVD Min = 1.25 EFL Max where the L1-L10 are lens elements progressively from the object to the image end; S1-S17 are the surfaces of the elements L1 -L10; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; F/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens; F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

12. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 11.8935 L1 0.0798 1.838 31.0 S2 -3.8378 0.0056 S3 -6.5885 L2 0.0694 1.834 37.3 S4 0.7527 0.1911 S5 0.9421 L3 0.0907 1.847 23.8 S6 1.6893

1.2104-0.0278 S7 0.8562 L4 0.1078 1.713 53.9 S8 -4.091 0.0667 Aperture 0.0278 S9 0.8246 L5 0.0758 1.776 43.1 S10 2.5812 0.0347 S11 -1.8940 L6 0.1971 1.847 23.8 S12 0.6235 0.1106 S13 -5.1768 L7 0.0703 1.837 31.8 S14 -0.891 EFL = 1.0 - 1.89 f/No. = 2.8 - 3.8 FVD Min = FVD FVD = 3.5 - 2.81 F1 = - 2.14 F2 = 1.17 /F1/F2/= 1.83 EFT MAY Where the L1-L7 are lens elements progressively from the object to the image end; S1-S14 are the surfaces of the elements L1-L7;Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens; F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

13. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 4.2729 L1 0.1206 1.556 52.7 S2 -1.5780 0.0262 S3 -1.5587 L2 0.0435 1.822 32.8 S4 0.6294 0.0392 S5 0.7856 L3 0.0435 1.487 70.4 S6 0.5727 L4 0.1136 1.817 24.6 S7 2.2725

1.1099-0.0412 Aperture 0.0217 S8 0.9014 L5 0.1585 1.72652.5 S9 -0.7056 L6 0.0391 1.812 24.7 S10 -1.6944 0.0043 S11 0.4907 L7 0.1680 1.508 68.0 S12 3.2951 0.0183 S13 -4.8528 L8 0.0466 1.640 34.6 S14 0.9599 0.0325 S15 -5.3715 L9 0.0391 1.744 44.8 S16 0.4732 0.0479 S17 6.7733 L10 0.0675 1.633 34.0 S18 0430.8615 EFL= 1.0-1.913 f No. = 3.5 FVD =

3.04 - 2.39 FVD Min F1=-2.22 F2=1.01 F1F2=2.2 EFLMa: < where the L1-L10 are lens elements progressively from the object to the image end; S1-S18 are the surfaces of the elements L1-L10; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens, F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

14. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 -4.9227 L1 0.0698 1.717 29.5 S2 -2.6979 0.0051 S3 -8.5570 L2 0.0641 1.834 37.3 S4 0.8838 0.1752 S5 1.1231 L3 0.1198 1.785 25.7 S6 3.1379 1.5304-0.0256 S7 0.9562 L4 0.0982 1.640 60.2 -10.2845 0.0051 S9 0.8053 L5 0.0662 1.670 57.3 S10 1.3796 0.0080 S11 0.8356 L6 0.0862 1.589 61.3 S12 2.1683 0.0423 Aperture 0.0290 S13 -9.2343 L7 0.1759 1.847 23.8 S14 0.5054 0.0990 S15 -46.3803 L8 0.598 S15 -1.2826 EFL = 1.0 - 2.0 F/No. = 2.8 - 3.8 FVD = 3.7 - 2.69 F1 = -2.48 F2 = 1.21 IF1/F2/ = 2.05 FVDMin =1.34 EFLMax where the L1 -L8 are lens elements progressively from the object to the image end; S1-S15 are the surfaces of the elements L1-L8; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens; F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

1.1099-0.0412 Aperture 0.0217 S8 0.9014 L5 0.1585 1.726 52.5 S9 -0.7056 L6 0.0391 1.812 24.7 S10 -1.6944 0.0043 S11 0.4907 L7 0.1680 1.508 68.0 S12 3.2951 0.0183 S13 -4.8528 L8 0.0466 1.640 34.6 S14 0.9599 0.0325 S15 -5.6715 L9 0.0391 1.744 44.8 S16 0.4732 0.0479 S17 6.7733 L10 0.0675 1.633 34.0 S18 -0.8615 EFL = 1.0 - 1.913 fSNo. = 3.5 FVD = 3.04 - 2.39 FVD Min Fs = -2.22 F2 = 1.01 !F,/F2, = 2.2 EFLMax where the L1-L10 are lens elements progressively from the object to the image end; S1-S18 are the surfaces of the elements L1-L10; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens, F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

15. A lens according to claim 1 defined substantially as follows: Surface Axial Distance Radius Between Surfaces Lens Surface (mm) (mm) Nd Vd S1 35.5093 L1 0.0814 1.722 28.3 S2 -3.8670 0.0056 S3 -17.7329 L2 0.0694 1.834 36.4 S4 0.7520 0.1838 S5 0.9353 L3 0.0972 1.847 23.8 S6 1.6898

1.2116-0.0278 S7 0.8892 L4 0.972 1.713 53.9 S8 -8.0494 0.0764 Aperture 0.0278 S9 0.7610 L5 0.0987 1.737 48.9 S10 2.5559 0.0313 S11 -2.3994 L6 0.0867 1.833 24.1 S12 1.8557 0.0174 S13 1.9095 L7 0.0500 1.833 24.1 S14 0.6181 0.0986 S15 -9.9100 L8 0.0725 1.838 31.4 S16 -0.9605 EFL = 1.0 - 1.89 f/No. = 2.8 - 3.8 FVD = 3.5 - 2.81 FVD Min Fa = -2.14 F2 = 1.18 /F,/F2/= 1.81 FVO Min 1 49 where the L1-L8 are lens elements prog ressively from the object to the image end; S1-S16 are the surfaces of the elements L1-L8; Nd is the index of refraction of the lens elements and Vd is the dispersion of the elements; f/No. is the relative aperture of the lens; FVD is the front vertex distance of the lens; EFL is the equivalent focal lengths of the lens; F1 is the equivalent focal length of the first lens group; and F2 is the equivalent focal length of the second lens group.

16. A zoom lens constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.