Zoom lens

Claim 2

A zoom lens comprising in order from the object side: a front lens unit having a negative refractive power, said front lens unit being movable on an optical axis for zooming operation, said front lens unit comprising a negative lens element and including no positive lens elements; and a rear lens unit having positive refractive power, said rear lens unit being movable on the optical axis for zooming operation, said rear lens unit comprising a plurality of optical elements arranged into two subunits, one of said subunits having positive optical power, the other of said subunits having negative optical power, said zoom lens having only two lens units.

Claim 3

A zoom lens comprising in order from the object side: a front lens unit having a negative refractive power, said front lens unit being movable on an optical axis for zooming operation, said front lens unit consisting of a single negative element, and a rear lens unit having positive refractive power and comprising only two subunits of optical elements, said rear lens unit being movable on an optical axis for zooming operation, said subunits, being a front subunit and a rear subunit, one of which subunits having positive optical power and one of which subunits having negative optical power, said zoom lens having only two lens units.

Claim 4

A zoom lens comprising in order from the object side: a front lens unit having a negative refractive power, said front lens unit being movable on an optical axis for zooming operation, said front lens unit consisting of a single negative element, and a rear lens unit having positive refractive power and comprising only two subunits of optical elements, said rear lens unit being movable on an optical axis for zooming operation, said subunits, being a front subunit and a rear subunit, one of which subunits having positive optical power and one of which subunits having negative optical power, said zoom lens having only two lens units.

Claim 5

A zoom lens according to claim 2 wherein said front subunit has positive power and said rear subunit has negative optical power.

Claim 6

A zoom lens according to claim 2 and further comprising an aperture stop located adjacent said rear subunit.

Claim 7

A zoom lens according to claim 2 and further comprising an aperture stop located between said two subunits.

Claim 8

A zoom lens according to claim 2 and further comprising an aperture stop located behind said rear subunit.

Claim 9

A zoom lens according to claim 3 and further comprising an aperture stop located adjacent said rear subunit.

Claim 10

A zoom lens according to claim 3 and further comprising an aperture stop located between said two subunits.

Claim 11

A zoom lens according to claim 3 and further comprising an aperture stop located behind said rear subunit.

Claim 12

A zoom lens consisting, in order from the object side, of the following lens units in combination: a front-most lens unit having a negative refractive power, said front lens unit being movable on an optical axis for zooming operation, said front lens unit consisting of a single negative lens component; and a rear-most lens unit having positive refractive power, said rear lens unit movable on an optical axis for zooming operation, said rear-most lens unit consisting of two lens components, a front lens component and a rear lens component, at least one of which being of positive optical power.

Claim 13

A zoom lens consisting, in order from the object side, of the following lens units in combination: a front-most lens unit having a negative refractive power, said front lens unit being movable on an optical axis for zooming operation, said front lens unit consisting of a single negative lens component; and a rear-most lens unit having positive refractive power, said rear lens unit movable on an optical axis for zooming operation, said rear-most lens unit consisting of two lens components, a front lens component and a rear lens component, at least one of which being of positive optical power.

Claim 14

A zoom lens according to claim 10 and in combination with an aperture stop, said aperture stop being located adjacent to said rear lens component.

Claim 15

A zoom lens according to claim 10 and in combination with an aperture stop located between said lens components of said rear-most lens units.

Claim 16

A zoom lens according to claim 10 wherein said front lens component is a cemented doublet.

Claim 17

A zoom lens according to claim 13 wherein said rear lens component is a meniscus lens component.

Claim 18

A zoom lens according to claim 10 wherein said rear lens component is a meniscus lens element.

Claim 19

A zoom lens according to claim 10 wherein said front lens component has positive power.

Claim 20

A zoom lens according to claim 10 wherein said rear lens component has negative power.

Claim 21

A zoom lens according to claim 14 wherein said rear lens component has negative power.

Claim 22

A zoom lens according to claim 16 wherein said rear lens component has negative power.

Claim 23

A zoom lens according to claim 10 wherein (a) said negative component of said front-most lens unit has a surface with a smaller radius of curvature facing said rear-most lens unit; (b) said front lens component of said rear-most lens unit having an external surface with a smaller radius of curvature facing said front-most lens unit; and (c) said rear lens component of said rear-most lens unit having a surface with a smaller radius of curvature facing said front lens component.

Claim 24

A zoom lens comprising in order from object side: a frontmost lens unit having negative refractive power, said frontmost lens unit being movable on an optical axis for zooming operation, said frontmost lens unit having only a single negative lens element having a front surface and a rear surface, said rear surface having a shorter radius of curvature than said front surface; and a rearmost lens unit having positive refractive power, said rearmost lens unit being movable on an optical axis for zooming operation, said rearmost lens unit comprising a first lens component having positive power and a second lens component having negative power.

Claim 25

A zoom lens comprising in order from object side: a frontmost lens unit having negative refractive power, said frontmost lens unit being movable on an optical axis for zooming operation, said frontmost lens unit having only a single negative lens element having a front surface and a rear surface, said rear surface having a shorter radius of curvature than said front surface; and a rearmost lens unit having positive refractive power, said rearmost lens unit being movable on an optical axis for zooming operation, said rearmost lens unit comprising a first lens component having positive power and a second lens component having negative power.

Claim 26

A zoom lens according to claim 21 wherein said first lens component of said rearmost lens unit is a singlet.

Claim 27

A zoom lens according to claim 21 wherein said first lens component of said rearmost lens unit is a cemented doublet.

Claim 28

A zoom lens according to claim 22 and further having the following parameters: TABLE 1 __________________________________________________________________________ Clear Glass Surface Aper. Radius Thickness N V __________________________________________________________________________ 1 27.50 r.sub.1 = 234.733 d.sub.1 = 2.50 1.501 56.4 2 22.58 r.sub.2 = 18.202 d.sub.2 = A 3 13.71 r.sub.3 = 11.774 d.sub.3 = 3.87 1.589 61.3 4 12.20 r.sub.4 = 96.685 d.sub.4 = 7.74 3.71 DIAPHRAGM 5 3.67 r.sub.5 = -11.609 d.sub.5 = 0.50 6 4.10 r.sub.6 = -14.870 d.sub.6 = 3.00 1.805 25.4 __________________________________________________________________________ LENS DIAPH BEST EF BF FF A LENGTH F/NO DIAM FOCUS __________________________________________________________________________ 69.99 62.72 58.58 4.491 22.101 16.0 3.71 -1.67 47.00 46.59 25.82 12.082 29.692 12.1 3.71 -1.30 35.01 38.17 8.73 20.000 37.610 10.0 3.71 -0.70 79.98 69.73 72.82 2.553 20.163 17.7 3.71 -1.77 __________________________________________________________________________ where the reference symbols r 1 , r 2 , . . . represent radii of curvature of the surfaces S1, S2 . . . of the respective lens elements L1, L2, L3, L4. The reference symbols d 1 , d 2 , . . . designate thickness of the respective lens elements and air spaces reserved therebetween, the reference N is an index of refraction and symbol V represents Abbe numbers of the respective lens elements.

Claim 29

A zoom lens according to claim 23 and further having the following parameters: TABLE 2 __________________________________________________________________________ Clear Glass Surface Aper. Radius Thickness N V __________________________________________________________________________ 1 31.90 r.sub.1 = 577.968 d.sub.1 = 3.000 1.498 67.0 2 26.19 r.sub.2 = 19.897 d.sub.2 = A 3 19.97 r.sub.3 = 14.684 d.sub.3 = 8.102 1.772 49.7 4 16.79 r.sub.4 = -49.920 d.sub.4 = 1.500 1.847 23.8 5 14.75 r.sub.5 = 127.413 d.sub.5 = 5.937 6 5.54 r.sub.6 = -13.821 d.sub.6 = 3.796 1.847 23.8 7 4.06 r.sub.7 = -19.858 d.sub.7 = 0.000 3.96 DIAPHRAGM __________________________________________________________________________ LENS DIAPH BEST FF BF FF A LENGTH F/NO DIAM FOCUS __________________________________________________________________________ 79.96 63.32 78.37 2.779 25.114 16.00 3.96 -1.02 52.90 45.55 37.16 9.951 32.286 11.50 3.96 -0.81 35.01 33.81 9.92 20.777 43.112 8.54 3.96 -0.48 __________________________________________________________________________ where the reference symbols r 1 , r 2 , . . . represent radii of curvature of the surfaces S1, S2 . . . of the respective lens elements L1, L2, L3, L4. The reference symbols d 1 , d 2 , . . . designate thickness of the respective lens elements and air spaces reserved therebetween, the reference N is an index of refraction and symbol V represents Abbe numbers of the respective lens elements.

Claim 30

A zoom lens according to claim 23 and further having the following parameters: TABLE 3 __________________________________________________________________________ Clear Glass Surface Aper. Radius Thickness N V __________________________________________________________________________ 1 21.10 r.sub.1 = 2193.850 d.sub.1 = 3.000 1.498 67.0 2 23.37 r.sub.2 = 17.160 d.sub.2 = A 3 18.72 r.sub.3 = 12.950 d.sub.3 = 7.480 1.772 49.7 4 15.91 r.sub.4 = -51.994 d.sub.4 = 1.500 1.847 23.8 5 13.71 r.sub.5 = 77.152 d.sub.5 = 5.430 6 5.33 r.sub.6 = ASPHERE d.sub.6 = 2.924 1.847 23.8 7 4.16 r.sub.7 = -17.606 d.sub.7 = 0.000 4.05 DIAPHRAGM __________________________________________________________________________ LENS DIAPH BEST EF BF FF A LENGTH F/NO DIAM FOCUS __________________________________________________________________________ 79.87 64.72 78.45 2.766 23.100 16.00 4.05 -.31 52.93 46.02 39.62 8.072 28.406 11.40 4.05 -.61 35.02 33.60 13.82 16.113 36.447 8.31 4.05 -.46 ##STR2## C = -.07806828 K = .34475 D = -0.4711 × 10.sup.-4 E = -0.1009 × 10.sup.-5 VERTEX RADIUS = -12.8093 __________________________________________________________________________ where the reference symbols r 1 , r 2 , . . . represent radii of curvature of the surfaces S1, S2 . . . of the respective lens elements L1, L2, L3, L4. The reference symbols d 1 , d 2 , . . . designate thickness of the respective lens elements and air spaces reserved therebetween, the reference N is an index of refraction and symbol V represents Abbe numbers of the respective lens elements, 1/C is a radius of curvature for the surface and K is a conic constant of the surface, y is a marginal ray height and D and E are aspheric coefficients of the surface.

Claim 31

The zoom lens of claim 21 and wherein said zoom lens has only three lens elements.

Claim 32

The zoom lens of claim 21 and wherein said zoom lens has only four lens elements and two of said elements are in the form of a doublet.

Claim 33

The zoom lens of claim 27 and wherein the zoom ratio is at least 2.

Claim 34

The zoom lens of claim 28 and wherein the zoom ratio is at least 2.

Claim 35

A zoom lens comprising in order from object side: a frontmost lens unit having negative refractive power, said frontmost lens unit being movable on an optical axis for zooming operation, said frontmost lens unit having only a single negative lens element having a front surface and a rear surface, said rear surface having a shorter radius of curvature than said front surface; and a rearmost lens unit having a positive refractive power, said rearmost lens unit being movable on an optical axis for zooming operations, said rearmost lens unit comprising a first lens component having positive power and a second lens component, said second lens component being a meniscus shaped lens element.

Claim 36

A zoom lens comprising in order from object side: a frontmost lens unit having negative refractive power, said frontmost lens unit being movable on an optical axis for zooming operation, said frontmost lens unit having only a single negative lens element having a front surface and a rear surface, said rear surface having a shorter radius of curvature than said front surface; and a rearmost lens unit having a positive refractive power, said rearmost lens unit being movable on an optical axis for zooming operations, said rearmost lens unit comprising a first lens component having positive power and a second lens component, said second lens component being a meniscus shaped lens element.

Claim 37

A zoom lens according to claim 31 wherein said first lens component of said rearmost lens unit is a singlet.

Claim 38

A zoom lens according to claim 31 wherein said first lens component of said rearmost lens unit is a cemented doublet.