Zoom lens

Abstract

A zoom lens having a range of equivalent focal lengths (EFL) which extend from a dimension above the diagonal of the film plane of the lens to a telephoto focal length, where the lens comprises three groups of which two are movable to vary the EFL.

Description

FIELD OF THE INVENTION

This invention relates to zoom lenses and, more particularly, relates to telephoto zoom lenses having a capability of very close focusing.

BACKGROUND OF THE INVENTION

Conventional telephoto zoom lenses are generally configured in four groups which are plus-minus-minus-plus or plus-minus-plus-plus and usually have a fixed aperture stop in the rear positive group which is also fixed in relation to the image planes. In these types of lenses, the size of the front group and therefore, the maximum diameter of the lens, is determined by the size of the entrance pupil at the long end of the zoom lens range. This requires that the smallest diameter the front group may have is the diameter of the entrance pupil at the long end of the range. Often, the diameter of the front group should be larger than that of the entrance pupil to satisfy relative illumination requirements at the edges of the images format. Therefore, if the lens is required to have a large relative aperture, the diameter of the front group is large, making the lens impractical and expensive for the high volume consumer market. Additionally, the large barrel diameter may be found objectionable by the user.

More modern forms of telephoto zoom lenses have the aperture stop and/or the rear group both moving during a zooming operation. These configurations usually result in a smaller physical size of the lens since the lens then has a variable relative aperture number. With the variable aperture, the lens is usually slower at the longer equivalent focal length (EFL), resulting in a smaller entrance pupil at that end. These forms of lenses generally require a more elaborate motion of the groups that move with zooming, with the front group possibly moving for both zooming and focusing. As a result, the mechanical configuration of the lens becomes more complicated than that of the conventional forms, and the lens more difficult to manufacture.

The conventional approach to the design of a zoom lens is to minimize lens group powers and maximize zooming group travel. That, in turn, means that the centration and the tilt tolerances have to be controlled quite accurately over relatively long travel distances. And since the motion of every zoom group is represented by a quadratic function, the long travel can often require zoom cams which must change the acceleration and the direction of motion of zooming groups. This may often result in designs which are difficult or simply impossible to physically realize.

The present lens provides a three group zoom lens of a plus-minus-plus configuration, wherein the front positive group is stationary with zooming and moves only for focusing, and the second negative group and the third positive group move in opposite directions relative to each other for zooming.

SUMMARY OF THE INVENTION

A lens embodying the invention comprises three groups, a first positive group which moves only for focusing; a second negative group; and a third positive group where the second negative group and the third positive group move in opposite direction relative to each other for zooming. As suggested by U.S. Pat. No. 4,307,943, the front group power is kept very strong. This permits a simple short focusing travel by the first group while focusing to magnification of 1:2 or closer. Since the focusing group is of relatively strong power, the first zooming group that is the second negative group is of also strong negative optical power. Consequently, it must travel only a short distance for zooming. The third group is a telephoto type lens, and it comprises two subgroups separated by a large airspace. The front or object side subgroup contains most of the power of the third group in order to keep the principal points of that group as close as possible to the front of the lens. The rear subgroup is of low optical power and may comprise as little as one element.

Having both of the zooming groups of strong powers allows their motion to be represented by shorter and smoother portions of the quadratic function. Consequently, zoom cams are smoother, and the centration and tilt tolerances of zooming groups can be better controlled in manufacturing, allowing for higher production yields.

The smooth, monotonic motion of both zooming groups also allows the weight and travel of the zoom groups to be balanced in such a way as to eliminate "zoom creep".

An object of this invention is to provide a new and improved telephoto zoom lens which is compact and which may be focused close to a magnification of 1:2.

Another object of this invention is to provide a new and improved compact telephoto zoom lens.

A further object of this invention is to provide a new and improved telephoto zoom lens which is relatively compact, has a large relative aperture, particularly at the shorter end of its EFL range, and which may be focused very close to an object to provide a magnification of approximately 1:2.

The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of this specification. The invention, however, together with further objects and advantages thereof, may best be appreciated by reference to the following detailed description taken in contunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-8 are schematic side elevations of lenses embodying the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

A lens embodying the invention comprises three optical groupings: G1, G2, and G3, as shown in the drawings. In the drawings, the reference G followed by an Arabic numeral designates a lens group. Individual lens elements are designated by the reference L followed by an Arabic numeral, and lens surfaces are designated by the letter S followed by an Arabic numeral. In all cases, the group lens elements and lens surfaces are numbered progressively from the object end to the image end of the lens.

In all examples, group G1 is positive, group G2 is negative, and group G3 is positive. Group G1 is preferably stationary during zooming and moves only for focusing, while the second negative group, G1, and the third positive group, G3, move in opposite directions to each other to accomplish change in the EFL.

In order to maintain a short focusing travel of the first group while focusing to a magnification of 1:2 or closer, the focal length of the first group, G1, is kept shorter than the shortest EFL of the overall range. This may be expressed as:

F.sub.1 <F.sub.s where F.sub.1 is the EFL of group G1 and F.sub.s is the shortest EFL of the lens.

Otherwise stated, the optical power of the first group is greater than the optical power of the overall lens at its shortest EFL.

Since the focusing group is of strong optical power, the first zooming group, G2, is also of strong optical power, but negative. Therefore, it requires only a short zooming motion to accomplish a magnification change between the shortest EFL and the longest EFL of the lens.

The ratio of focal lengths of the first and the second groups should satisfy the following relationship:

2.0<.vertline.F.sub.1 /F.sub.2 .vertline.<2.85

If the upper limit of this relationship is exceeded, then the distortion and the spherical aberration introduced by the negative zooming group becomes extremely difficult to correct with limited degrees of freedom available in the following second zooming group. If the lower limit of the above relationship is not satisfied, then the amounmt of travel of the first zooming group becomes too large for the requirements of compactness to be met.

The focal length of the third positive group is chosen to satisfy the following relationship:

1.0F.sub.1 <F.sub.3 <1.85F.sub.1

If the EFL F.sub.3 of the third group, G3, is lower than the lower limit of the immediate preceding relationship, it becomes very difficult to correct aberrations, particularly spherical aberrations and distortion introduced by very strong first and second groups. If the EFL F.sub.3 of the third group, G3, is greater than the upper limit of the foregoing relationship, the total travel of the third group during zooming and the size of the overall lens becomes large and may be unacceptable.

The third group is divided into two subgroups, G3a and G3b, separated by a wide airspace, D3. The front subgroup has the majority of the power of the third group to keep the principal points of that group as close as possible to the front. The rear subgroup has low optical power and may comprise only one element, as shown in FIG. 6.

Lenses embodying the invention consisting of three lens groups have group powers in a ratio to the geometric means of the power of the lens, as set forth in Table VIII hereto. A lens embodying the invention has the following powers:

2.2>K.sub.1 /K.sub.M >1.4 4.8>.vertline.K.sub.2 /K.sub.M .vertline.>3.4 2.9>K.sub.3 /K.sub.M >2.3 where K.sub.M =.sqroot.K.sub.S K.sub.L and K.sub.S is the power of the lens at the shortest EFL thereof, K.sub.L is the power of the lens at the longest EFL thereof and K.sub.1, K.sub.2 and K.sub.3 are the optical powers of said first, second and third groups, respectively.

In the following tables, lenses embodying the invention as scaled to an image frame of 24.times.36 mm are set forth. In the tables, lens elements are designated by L followed by an Arabic numeral progressively from the object to image end. Positive radii are struck from the right and negative radii are struck from the left on the optical axis. Lens surfaces are designated by S followed by an Arabic numeral progressively from the object to the image end. The index of refraction of each lens element is given as N.sub.D and the dispersion as measured by the Abbe Number by V.sub.D. The spacing of groups G2 at various zoom positions from Group G1 is given as D1 and the spacing of group G2 from Group G3 is given as D2. The back focal length of the lens (BFL) is the distance from the rear surface of the last lens element on the optical axis to the film plane FP which coincides with the intended image plane of the camera. The spacing of the subgroups of the third group is given by D3.

A lens embodying the invention may have one or more surfaces which are aspheric and defined by the equation ##EQU1## where X is the surface at a semi-aperture distance y from the optical axis of the lens, C is the curvature of the surface at the optical axis equal to the reciprocal of the radius, K is a conic constant or other surface of revolution, and D, E, F, and G are constants.

Table I defines a lens embodying the invention as shown in FIG. 1.

TABLE I______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 57.79L1 3.00 1.805 25.5 S2 36.55L2 12.20 1.564 60.8 S3 -203.97 .10 S4 73.11L3 4.00 1.658 50.9 S5 147.31 D1 S6 5646.19L4 2.00 1.773 49.6 S7 39.02 6.20 S8 -44.79L5 2.00 1.713 53.9 S9 36.71L6 6.00 1.805 25.5 S10 1391.85 D2 S11 118.44L7 5.00 1.487 70.4 S12 -202.53 .10 S13 66.67L8 4.00 1.702 41.2 S14 228.83 .10 S15 45.89L9 8.00 1.487 70.4 S16 -73.04L10 1.50 1.785 26.1 S17 180.77 23.51 S18 37.07L11 4.00 1.487 70.4 S19 73.88L12 1.80 1.575 41.5 S20 31.01 1.20 S21 49.17L13 5.00 1.517 52.2 S22 -58.36 11.66 S23 -27.51L14 1.80 1.773 49.6 S24 438.24 .10 S25 120.08L15 3.50 1.805 25.5 S26 -377.00______________________________________Relative Aperture = 2.86-4.14Aperture 3.43 mm after surface S17EFL 74.04-196.26 mm______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________74.0 3.67 mm 39.19 mm 39.03 mm133.57 10.24 16.31 54.56196.26 13.86 .50 64.44______________________________________

Table II defines a lens embodying the invention as shown in FIG. 2:

TABLE II______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 57.13L1 3.00 1.805 25.5 S1 38.71L2 11.00 1.511 60.5 S3 -206.5 .20 S4 66.63L3 4.00 1.511 60.5 S5 236.48 D1 S6 -1808.22L4 2.20 1.773 49.5 S7 42.9 7.00 S8 -53.64L5 2.00 1.711 54.2 S9 38.31L6 6.50 1.805 25.5 S10 380.11 D2 S11 117.93L7 4.50 1.665 59.0 S12 -174.33 .10 S13 42.80L8 4.50 1.602 54.0 S14 775.73 .10 S15 114.46L9 4.50 1.809 46.4 S16 644.83 .60 S17 -2850.47L10 5.00 1.481 71.6 S18 -54.13L11 1.50 1.785 26.1 S19 92.26 22.86 S20 260.57L12 3.00 1.773 34.1 S21 -56.45 11.59 S22 -28.86L13 1.50 1.789 41.4 S23 33.20L14 4.80 1.487 70.4 S24 -166.68 .10 S25 53.96L15 3.50 1.785 25.7 S26 231.05______________________________________Relative Aperture 2.8-4.1Aperture .0034 mm after surface S21EFL 72.1-203.5 mm______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________72.1 3.45 mm 44.07 mm 38.60 mm135.0 6.07 17.73 59.15203.5 10.28 .50 72.15______________________________________

Table III defines a lens embodying the invention as shown in FIG. 3:

TABLE III______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 64.12L1 3.00 1.805 25.5 S2 41.91L2 8.20 1.500 67.1 S3 -257.89 .20 S4 69.28L3 4.00 1.492 68.4 S5 -1014.42 D1 S6 -368.70L4 3.00 1.773 49.6 S7 42.37 4.64 S8 -43.61L5 2.50 1.660 58.6 S9 39.90L6 4.00 1.805 25.5 S10 421.14 D2 S11 90.55L7 4.50 1.569 66.3 S12 -220.96 .10 S13 67.11L8 4.50 1.635 58.4 S14 550.02 .32 S15 55.37L9 6.00 1.487 70.4 S16 -83.00L10 1.50 1.780 26.2 S17 626.54 11.14 S18 31.70L11 4.42 S19 23.41 23.41 S20 30.82L12 3.50 1.491 58.3 S21 34.79______________________________________Relative Aperture 2.8-4.1Aperture 9.64 mm after surface S17EFL 72.1-203.5 mm______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________72.1 mm 2.26 mm 4.17 mm 52.38 mm135.0 11.68 17.62 66.49203.5 15.76 .50 79.55______________________________________Aspheric Surface - S21K = -.010D = .318 .times. 10.sup.-5E = -.587 .times. 10.sup.-8F = .398 .times. 10.sup.-10G = -.962 .times. 10.sup.-13______________________________________

Table IV defines a lens embodying the invention as shown in FIG. 4:

TABLE IV______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 58.324L1 3.000 1.785 26.1 S2 39.608L2 12.000 1.487 70.4 S3 -175.640 .100 S4 61.445L3 4.300 1.487 70.4 S5 258.513 D1 S6 -491.316L4 3.400 1.834 37.3 S7 -59.685L5 1.800 1.773 49.6 S8 37.576 6.210 S9 -40.656L6 1.800 1.640 60.2 S10 41.069L7 4.400 1.805 25.5 S11 364.418 D2 S12 115.149L8 3.800 1.487 70.4 S13 -135.833 .100 S14 63.229L9 3.600 1.589 61.3 S15 222.510 .100 S16 47.681L10 7.700 1.487 70.4 S17 -59.094L11 2.200 1.805 25.5 S18 981.386 25.958 S19 251.278L12 4.100 1.603 38.0 S20 -57.139 14.178 S21 -25.510L13 2.200 1.834 37.3 S22 -120.287 .200 S23 321.054L14 2.400 1.762 26.6 S24 -160.611______________________________________Aperture stop 6.70 mm after surface S18Relative Aperture f/2.9-f/4.0EFL 72.13 mm-203.79 mm______________________________________ZOOM SPACING DATAf/NO. EFL D1 D2 BFL______________________________________2.89 72.132 mm 2.500 mm 3.490 38.9973.49 134.911 10.692 15.947 52.3524.01 203.786 14.468 .500 64.025______________________________________

Table V defines a lens embodying the invention as shown in FIG. 5:

TABLE V______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 54.948L1 3.000 1.805 25.5 S2 34.0161L2 12.200 1.654 60.8 S2 -170.280 .100 S4 66.202L3 4.000 1.669 44.9 S5 177.569 D1 S6 53285.281L4 2.000 S7 37.063 6.611 S8 -45.053L5 2.000 1.697 55.5 S9 33.594L6 6.00 1.805 25.5 S10 359.1997 D2 S11 80.455L7 4.000 1.720 50.3 S12 -2985.481 .100 S13 45.138L8 4.000 1.640 60.2 L14 324.248 .100 S15 120.439L9 7.400 1.487 70.4 S16 -76.160L10 1.800 1.785 26.1 S17 105.400 3.543 S18 155.381L11 4.00 1.785 25.7 S19 165.446 21.695 S20 64.585L12 4.800 1.487 70.4 S21 -42.160 5.771 S22 -27.547L13 1.800 S23 182.230L14 3.500 1.785 25.7 S24 -135.578______________________________________Aperture stop 11.02 mm after surface S19Relative Aperture = f/3.50-4.60EFL 77.86-197.80______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________77.86 mm 1.16 mm 70.52 mm 56.44 mm135.14 5.28 26.64 76.44197.80 8.31 10.04 89.97______________________________________

Table VI defines a lens embodying the invention as shown in FIG. 6:

TABLE VI______________________________________ SURFACE AXIAL DISTANCE RADII BETWEEN SURFACESLENS (mm) (mm) N.sub.D V.sub.D______________________________________ S1 57.608L1 3.000 1.805 2.55 S2 39.733L2 11.700 1.487 70.4 S3 -191.098 .100 S4 64.318L3 4.600 1.487 70.4 S5 361.085 D1 S6 -477.713L4 2.500 1.785 26.1 S7 -135.642L5 1.800 S8 38.56 5.900 S9 -42.385L6 2.000 1.640 60.2 S10 38.063L7 5.300 1.785 25.7 S11 351.153 D2 S12 124.387L8 3.900 1.487 70.4 S13 -142.452 .100 S14 68.977L9 3.900 1.487 70.4 S15 PLANO .100 S16 53.977L10 8.300 1.487 70.4 S17 -50.419L11 1.800 1.785 26.1 S18 -3696.262 19.386 S19 388.069L12 12.932 1.648 33.8 S20 -61.324 18.143 S21 -26.200L13 1.500 1.806 40.7 S22 -63.333______________________________________ Aperture stop 17.96 mm after S18 Relative Aperture f/2.9-f/4.1 EFL 73.7 mm-197.4 mmZOOM SPACING DATAEFL D1 D2 BFL______________________________________ 73.70 mm 4.17 mm 36.92 mm 39.01 mm133.61 11.92 15.79 51.69197.44 15.42 .50 63.19______________________________________

Table VII defines a lens embodying the invention as shown in FIG. 7:

TABLE VII______________________________________ SURFACE AXIAL DISTANCE RADII BETWEEN SURFACESLENS (mm) (mm) N.sub.D V.sub.D______________________________________ S1 60.260L1 2.000 1.805 25.5 S2 35.650L2 9.589 1.607 56.7 S3 -700.208 .200 S4 91.232L3 3.792 1.603 60.7 S5 1841.514 Z1 S6 -151.106L4 1.500 1.806 40.7 S7 32.611 6.202 S8 -45.164L5 1.500 1.487 70.4 S9 37.878L6 4.873 1.847 23.83 S10 370.653 Z2 S11 79.526L7 4.002 1.785 25.7 S12 -241.015 .200 S13 45.118L8 8.012 1.564 60.8 S14 -44.880L9 1.500 1.805 25.5 S15 51.885 .200 S16 28.552L10 6.422 1.623 58.1 S17 410.023 22.391 S18 44.912L11 1.500 1.834 37.3 S19 18.917 .419 S20 18.705L12 3.949 1.617 36.61 S21 -145.878 1.989 S22 -19.411L13 1.500 1.678 53.4 S23 -55.447______________________________________Aperture stop 7.940 mm after Surface S17ZOOM SPACING DATAf/ EFL Z1 Z2 BFL______________________________________2.9 70.57 mm 2.00 mm 25.77 mm 40.49 mm3.1 85.00 5.35 19.67 43.343.3 105.00 8.18 12.43 47.653.6 145.00 11.88 1.00 55.38______________________________________

Table VIII defines a lens embodying the invention as shown in FIG. 8:

TABLE VIII______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ SI 85.153L1 4.500 1.517 64.2 L2 577.955 .100 S3 77.955L2 9.500 1.589 61.3 S4 -186.300L3 2.700 1.805 25.5 S5 293.223 .100 S6 91.444L4 5.500 1.517 64.2 S7 -1705.019 Z1 S8 -2183.251L5 2.000 1.773 49.6 S9 35.305 6.795 S10 -47.951L6 2.000 1.697 55.5 S11 36.239L7 6.000 1.805 25.5 S12 348.673 Z2 S13 75.843L8 4.000 1.770 46.8 S14 -399.249 .100 S15 51.469L9 4.000 1.653 58.9 S16 322.350 .100 S17 77.230L10 7.400 1.487 70.4 S18 -81.272L11 1.800 1.785 26.1 S19 81.349 29.293 S20 46.199L12 4.800 1.497 68.6 S21 -83.668 9.333 S22 -31.364L13 1.800 1.773 49.6 S23 551.639L14 3.500 1.785 25.7 S24 -113.624______________________________________Aperture stop 8.264 mm after Surface S20.ZOOM SPACING DATAf/ EFL Z1 Z2 BFL______________________________________2.86 72.48 mm 4.14 mm 38.99 mm 39.07 mm3.67 134.93 10.64 16.259 55.284.14 202.43 14.26 .85 67.09______________________________________

Table IX sets forth the EFL's of each group of the lenses of Tables I-VII, where F.sub.1 is the EFL of a group G1, F.sub.2 is the EFL of group G2, and F.sub.3 is the EFL of group G3.

TABLE IX______________________________________TABLE F.sub.1 F.sub.2 F.sub.3 F.sub.1 /F.sub.3 .vertline.F.sub.1 /F.sub.2 .vertline .______________________________________I 69.4 -28.3 44.3 1.57 2.45II 69.4 -30.2 48.1 1.44 2.29III 69.4 -28.6 50.4 1.38 2.42IV 69.4 -26.8 43.3 1.60 2.59V 59.5 -26.5 53.4 1.11 2.24VI 69.5 -26.9 42.2 1.65 2.58VII 68.4 -29.1 39.2 1.75 2.35VIII 69.4 -25.9 45.8 1.52 2.68______________________________________

A lens embodying the invention may also be defined by the ratio of the optical powers of the individual groups to the geometric mean of the power of the lens.

The geometric mean (K.sub.M) of the powers of each lens is

K.sub.M =.sqroot.K.sub.S K.sub.L where K.sub.S and K.sub.L are the optical powers of the lens expressed as the reciprocal of its equivalent focal length in millimeters at the shortest (K.sub.S) and longest (K.sub.L) EFL's, respectively.

In the examples hereinafter set forth, K.sub.M =0.0080 in the lens of Table V, K.sub.m =0.0099 in the lens of Table VII, and in all the other tables K.sub.M =0.0083.

Table X sets forth the ratio of the optical powers of each lens group of Tables I-VI to the geometric mean of the power of each lens.

TABLE X______________________________________TABLE K.sub.1 /K.sub.M K.sub.2 /K.sub.M K.sub.3 /K.sub.M______________________________________I 1.73 -4.27 2.72II 1.73 -3.99 2.512III 1.73 -4.33 2.39IV 1.73 -4.50 2.78V 2.10 -4.70 2.38VI 1.73 -4.48 2.86VII 1.47 -3.47 2.57VIII 1.73 -4.65 2.63______________________________________

The invention provides a three group zoom lens having a zoom range of substantially 3:1 in the telephoto range with movement of only the second and third groups, which lens is compact and has a large relative aperture.

It may thus be seen that the objects of the invention are efficiently attained. While preferred embodiments of the invention have been set forth for purposes of disclosure, other embodiments and modifications of the disclosed embodiments may occur to others skilled in the art. Accordingly, the appended claims are intended to cover all embodiments of the invention which do not depart from the spirit and scope of the invention.

Claims

1. A zoom lens having a range of equivalent focal lengths in which the lowest equivalent focal length of the lens is greater than the diagonal of the image frame of the lens, said lens from the object end consisting of a first positive group, a second negative group and a third positive group, said first group having an optical power K.sub.1, said second group having an absolute optical power K.sub.2, said third group having an optical power K.sub.3 and

2.2>K.sub.1 /K.sub.M >1.4

4.8>.vertline.K.sub.2 /K.sub.M .vertline.>3.4

2.9>K.sub.3 /K.sub.M >2.3

where K.sub.M is the geometric mean of the equivalent focal lengths of said lens, said first group being axially movable only for focusing and said second and third groups being movable in opposite directions to vary the equivalent focal length of said lens.

2. The lens of claim 1 wherein

f.sub.1 <f.sub.3 <1.85 f.sub.1

where f.sub.1 and f.sub.3 are the equivalent focal lengths of said first and third groups.

3. The lens of claim 1 where

2.0<.vertline.f.sub.1 /f.sub.2 .vertline.<2.85

where f.sub.1 and f.sub.2 are the equivalent focal lengths of said first and second groups.

4. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ SURFACE AXIAL DISTANCE RADII BETWEEN SURFACESLENS (mm) (mm) N.sub.D V.sub.D______________________________________ S1 57.79L1 3.00 1.805 25.5 S2 36.55L2 12.20 1.564 60.8 S3 -203.97 .10 S4 73.11L3 4.00 1.658 50.9 S5 147.31 D1 S6 5646.19L4 2.00 1.773 49.6 S7 39.02 6.20 S8 -44.79L5 2.00 1.713 53.9 S9 36.71L6 6.00 1.805 25.5 S10 1391.85 D2 S11 118.44L7 5.00 1.487 70.4 S12 -202.53 .10 S13 66.67L8 4.00 1.702 41.2 S14 228.83 .10 S15 45.89L9 8.00 1.487 70.4 S16 -73.04L10 1.50 1.785 26.1 S17 180.77 23.51 S18 37.07L11 4.00 1.487 70.4 S19 73.88L12 1.80 1.575 41.5 S20 31.01 1.20 S21 49.17L13 5.00 1.517 52.2 S22 -58.36 11.66 S23 -27.51L14 ?.80 1.773 49.6 S24 438.24 .10 S25 120.08L15 3.50 1.805 25.5 S26 -377.00______________________________________

where L1-L15 are lens elements from the object to the image end of the lens, S1-S26 are surface radii of the elements L1-L15, N.sub.D is the index of refraction of each of the lens elements specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________74.0 3.67 mm 39.19 mm 39.03 mm133.57 10.24 16.31 54.56196.26 13.86 .50 64.44______________________________________

5. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES(mm) N.sub.D V.sub.D______________________________________ S1 57.13L1 3.00 1.805 25.5 S1 38.71L2 11.00 1.511 60.5 S3 -206.5 .20 S4 66.63L3 4.00 1.511 60.5 S5 236.48 D1 S6 -1808.22L4 2.20 1.773 49.5 S7 42.9 7.00 S8 -53.64L5 2.00 1.711 54.2 S9 38.31L6 6.50 1.805 25.5 S10 380.11 D2 S11 117.93L7 4.50 1.665 59.0 S12 -174.33 .10 S13 42.80L8 4.50 1.602 54.0 S14 775.73 .10 S15 114.46L9 4.50 1.809 46.4 S16 644.83 .60 S17 -2850.47L10 5.00 1.481 71.6 S18 -54.13L11 1.50 1.785 26.1 S19 92.26 22.86 S20 260.57L12 3.00 1.773 34.1 S21 -56.45 11.59 S22 -28.86L13 1.50 1.789 41.4 S23 33.20L14 4.80 1.487 70.4 S24 -166.68 .10 S25 53.96L15 3.50 1.785 25.7 S26 231.05______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________72.1 3.45 mm 44.07 mm 38.60 mm135.0 6.07 17.73 59.15203.5 10.28 .50 72.15______________________________________

6. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES(mm) N.sub.D V.sub.D______________________________________ S1 58.324L1 3.000 1.785 26.1 S2 39.608L2 12.000 1.487 70.4 S3 -175.640 .100 S4 61.445L3 4.300 1.487 70.4 S5 258.513 D1 S6 -491.316L4 3.400 1.834 37.3 S7 -59.685L5 1.800 1.773 49.6 S8 37.576 6.210 S9 -40.656L6 1.800 1.640 60.2 S10 41.069L7 4.400 1.805 25.5 S11 364.418 D2 S12 115.149L8 3.800 1.487 70.4 S13 -135.833 .100 S14 63.229L9 3.600 1.589 61.3 S15 222.510 .100 S16 47.681L10 7.700 1.487 70.4 S17 -59.094L11 2.200 1.805 25.5 S18 981.386 25.958 S19 251.278L12 4.100 1.603 38.0 S20 - 57.139 14.178 S21 -25.510L13 2.200 1.834 37.3 S22 -120.287 .200 S23 321.054L14 2.400 1.762 26.6 S24 -160.611______________________________________

where L1-L14 are lens elements from the object to the image end of the lens, S1-S22 are surface radii of the elements L1-L14, N.sub.D is the index of refraction of each of the lens elements specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAf/NO. EFL D1 D2 BFL______________________________________2.89 72.132 mm 2.500 mm 3.490 38.9973.49 132.911 10.692 15.947 52.3524.01 203.786 14.468 .500 64.025______________________________________

7. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII (mm) SURFACES(mm) N.sub.D V.sub.D______________________________________ S1 54.948L1 3.000 1.805 25.5 S2 34.0161L2 12.200 1.654 60.8 S2 -170.280 .100 S4 66.202L3 4.000 1.669 44.9 S5 177.569 D1 S6 53285.281L4 2.000 S7 37.063 6.611 S8 -45.053L5 2.000 1.697 55.5 S9 33.594L6 6.00 1.805 25.5 S10 359.1997 D2 S11 80.455L7 4.000 1.720 50.3 S12 -2985.481 .100 S13 45.138L8 4.000 1.640 60.2 L14 324.248 .100 S15 120.439L9 7.400 1.487 70.4 S16 -76.160L10 1.800 1.785 26.1 S17 105.400 3.543 S18 155.381L11 4.00 1.785 25.7 S19 165.446 21.695 S20 64.585L12 4.800 1.487 70.4 S21 -42.160 5.771 S22 -27.547L13 1.800 S23 182.230L14 3.500 1.785 25.7 S24 -135.578______________________________________

where L1-L14 are lens elements from the object to the image end of the lens, S1-S24 are surface radii of the elements L2-L14, N.sub.D is the index of refraction of each of the lens elements as specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________77.86 mm 1.16 mm 70.52 mm 56.44 mm135.14 5.28 26.64 76.44197.80 8.31 10.04 89.97______________________________________

8. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ AXIAL DISTANCE SURFACE BETWEENLENS RADII(mm) SURFACES(mm) N.sub.D V.sub.D______________________________________ S1 57.608L1 3.000 1.805 2.55 S2 39.733L2 11.700 1.487 70.4 S3 -191.098 .100 S4 64.318L3 4.600 1.487 70.4 S5 361.085 Z1 S6 -477.713L4 2.500 1.785 26.1 S7 0135.642L5 1.800 1.773 49.6 S8 38.56 5.900 S9 -42.385L6 2.000 1.640 60.2 S10 38.063L7 5.300 1.785 25.7 S11 351.153 Z2 S12 124.387L8 3.900 1.487 70.4 S13 -142.452 .100 S14 68.977L9 3.900 1.487 70.4 S15 PLANO .100 S16 53.977L10 8.300 1.487 70.4 S17 -50.419L11 1.800 1.785 26.1 S18 -3696.262 18.386 S19 -61.324L12 12.932 1.648 33.8 S20 18.143 S21 -26.200L13 1.500 1.806 40.7 S22 -63.333______________________________________

where L1-L13 are lens elements from the object to the image end of the lens, S1-S22 are surface radii of the elements L1-L13, N.sub.D is the index of refraction of each of the lens elements as specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________73.70 mm 4.17 mm 36.92 mm 39.01 mm133.61 11.92 15.79 51.69197.44 15.42 .50 63.19______________________________________

9. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ SURFACE AXIAL DISTANCE RADII BETWEENLENS (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 60.260L1 2.000 1.805 25.4 S2 35.650L2 9.589 1.607 56.7 S3 700.208 .200 S4 91.232L3 3.792 1.603 60.7 S5 1841.514 Z1 S6 -151.106L4 1.500 1.806 40.7 S7 32.611 6.202 S8 -45.164L5 1.500 1.487 70.4 S9 37.878L6 4.873 1.847 23.83 S10 370.653 Z2 S11 79.526L7 4.002 1.785 25.7 S12 -241.015 .200 S13 45.118L8 8.012 1.564 60.8 S14 -44.880L9 1.500 1.805 25.5 S15 51.885 .200 S16 28.552L10 6.422 1.623 58.1 S17 410.023 22.391 S18 44.912L11 1.500 1.834 37.3 S19 18.917 .419 S20 18.705L12 3.949 1.617 36.61 S21 -145.878 1.989 S22 -19.411L13 1.500 1.678 53.4 S23 -55.447______________________________________

where L1-L13 are lens elements from the object to the image end of the lens, S1-S23 are surface radii of the elements L1-L13, N.sub.D is the index of refraction of each of the elns elements as specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAf/ EFL Z1 Z2 BFL______________________________________2.9 70.57 mm 2.00 mm 25.77 mm 40.49 mm3.1 85.00 5.352 19.67 43.343.3 105.00 8.183 12.431 47.653.6 145.00 11.880 1.000 55.38______________________________________

10. A lens according to claim 1 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ SURFACE AXIAL DISTANCE RADII BETWEENLENS (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ SI 85.153L1 4.500 1.517 64.2 L2 577.955 1.000 S3 77.955L2 9.500 1.589 61.3 S4 -L86.300L3 2.700 1.805 25.5 S5 293.223 .100 S6 91.444L4 5.500 1.517 64.2 S7 -1705.019 Z1 S8 -2183.251L5 2.000 1.773 49.6 S9 35.305 6.795 S10 -47.951L6 2.000 1.697 55.5 S11 36.240L7 6.000 1.805 25.5 S12 348.673 Z2 S13 75.843L8 4.000 1.770 46.8 S14 -399.249 .100 S15 51.469L9 4.000 1.653 58.9 S16 322.350 .100 S17 77.230L10 7.400 1.487 70.4 S18 -81.272L11 1.800 1.785 26.1 S19 81.239 29.293 S20 46.199L12 4.800 1.497 68.6 S21 - 83.668 9.333 S22 -31.364L13 1.800 1.773 49.6 S23 551.639L14 3.500 1.785 25.7 S24 -113.624______________________________________ZOOM SPACING DATAf/ EFL Z.sub.1 Z.sub.2 BFL______________________________________2.86 72.48 mm 4.14 mm 38.99 mm 39.07 mm3.67 134.93 10.64 16.25 55.284.14 202.43 14.26 .85 67.09______________________________________

11. A lens according to claim 1 having at least one aspheric surface defined by the equation ##EQU2## where X is the surface at a semi-aperture distance y from the optical axis of the lens, C is the curvature of the surface at the optical axis equal to the reciprocal of the radius, K is a conic constant or other surface of revolution, and D, E, F, and G are constants.

12. A lens according to claim 11 scaled to an image frame of 24.times.36 mm defined substantially as follows:

______________________________________ SURFACE AXIAL DISTANCE RADII BETWEENLENS (mm) SURFACES (mm) N.sub.D V.sub.D______________________________________ S1 64.12L1 3.00 1.805 25.5 S2 41.91L2 8.20 1.500 67.1 S3 -257.89 .20 S4 69.28L3 4.00 1.492 68.4 S5 -1014.42 D1 S6 -368.70L4 3.00 1.773 49.6 S7 42.37 4.64 S8 -43.61L5 2.50 1.660 58.6 S9 39.90L6 4.00 1.805 25.5 S10 421.14 D2 S11 90.55L7 4.50 1.569 66.3 S12 -220.96 .10 S13 67.11L8 4.50 1.635 58.4 S14 550.02 .32 S15 55.37L9 6.00 1.487 70.4 S16 -83.00L10 1.50 1.780 26.2 S17 626.54 11.14 S18 31.70L11 4.42 1.834 37.3 S19 23.41 23.41 S20 30.82L12 3.50 1.491 58.3 S21 34.79______________________________________

where L1-L12 are lens elements from the object to the image end of the lens, S1-S21 are surface radii of the elements L1-L12, N.sub.D is the index of refraction of each of the lens elements specified, and V.sub.D is the dispersion of each lens element as measured by its Abbe number.

______________________________________ZOOM SPACING DATAEFL D1 D2 BFL______________________________________72.1 mm 2.26 mm 4.17 mm 52.38 mm135.0 11.68 17.62 66.49203.5 15.76 .50 79.55______________________________________Aspheric Surface S21 K = -.010 D = .318 z 10.sup.-5 E = -.587 .times. 10.sup.-8 F = .398 z 10.sup.-10 G = -.962 .times. 10.sup.-13______________________________________