Zoom lens system

Claim 2

A zoom lens system having an optical axis comprising a front lens group comprising a negative meniscus lens L1 at the front convex to front and a positive lens L3 having the face of greater curvature faced to front, and a rear lens group comprising a positive lens L4 having the face of greater curvature faced to front, a positive meniscus lens L5 convex to front, a negative lens L6 having the face of greater curvature faced to rear and a positive lens L7, the front and rear lens groups being moved in the opposite directions along said optical axis to vary the focal length of the lens system, wherein the zoom lens system satisfies the following conditions where the focal length of the front lens group is fA, the radius of curvature of the concave face of the negative meniscus lens L1 is r2, the radius of curvature of the front face of the positive lens L3 is r5, the radius of curvature of the convex face of the positive meniscus lens L5 is r9, the radius of curvature of the rear face of the negative lens L6 is r12 and the Abbe dispersion number of the positive lens L3 is ν3; -2.3<fA<-1.5, 0.45<r2<0.65, 0.5<r5<1.0, 0.4<r9<0.6, 0.3<r12<0.55, and ν3<40, said values being normalized to a wide-angle focal length of one (f'w=1.0).

Claim 3

A zoom lens system as defined in claim 1 wherein the following conditions are satisfied ______________________________________ r1 = 1.23815 d1 = 0.036 N1 = 1.744 ν1 = 44.9 r2 = 0.52874 d2 = 0.1711 r5 = 0.53579 d5 = 0.099 N3 = 1.80518 ν3 = 25.5 r6 = 0.62689 d6 = 0.8367 ˜ 0.0225 r7 = 0.59616 d7 = 0.0675 N4 = 1.6968 ν4 = 55.6 r8 = 3.76112 d8 = 0.0045 r9 = 0.4317 d9 = 0.063 N5 = 1.6779 ν5 = 55.5 r10 = 1.6554 d10 = 0.0779 r11 = -28.69185 d11 = 0.027 N6 = 1.80518 ν6 = 25.5 r12 = 0.33789 d12 = 0.108 r13 = 2.99972 d13 = 0.1162 N7 = 1.76182 ν7 = 26.5 r14 = -1.2919 ______________________________________ where the radii of curvature of the refracting surfaces, the axial air separations or thicknesses of lenses, the refractive indices for the sodium d-line and the Abbe dispersion numbers of the lenses L1 and L3 to L7 are designated in order from front to rear at r1, r2, r3 to r14, d1, d2, d5 to d13, N1, N3 to N7 and 1, ν3 to ν7.

Claim 4

A zoom lens system as defined in claim 1 wherein said front lens group further comprises a negative lens L2 located between said negative meniscus lens L1 and said positive lens L3.

Claim 5

A zoom lens system as defined in claim 3 wherein the following conditions are satisfied ______________________________________ r1 = 2.8088 d1 = 0.0365 N1 = 1.68893 ν1 = 31.1 r2 = 0.58955 d2 = 0.1415 r3 = 12.6753 d3 = 0.0274 N2 = 1.62299 ν2 = 58.1 r4 = 1.00509 d4 = 0.0046 r5 = 0.73126 d5 = 0.146 N3 = 1.68893 ν4 = 31.1 r6 = -76.0507 d6 = 0.92311 ˜ 0.02373 r7 = 0.64269 d7 = 0.0685 N4 = 1.6968 ν4 = 55.6 r8 = 5.24504 d8 = 0.0046 r9 = 0.47139 d9 = 0.0639 N5 = 1.6779 ν5 = 55.5 r10 = 0.98131 d10 = 0.1264 r11 = 11.4077 d11 = 0.0274 N6 = 1.80518 ν6 = 25.5 r12 = 0.36622 d12 = 0.1052 r13 = 1.43044 d13 = 0.12 N7 = 1.6668 ν7 = 33.1 r14 = -1.43044 ______________________________________ where r, d, N and ν, respectively, designate the radii of curvature of the refracting surfaces, the axial air separations or thickness of lenses, the refractive indices for the sodium d-line and the Abbe dispersion numbers numbered by subscripts in order from front to rear.

Claim 6

A zoom lens system as defined in claim 3 wherein the following conditions are satisfied ______________________________________ r1 = 2.15763 d1 = 0.0374 N1 = 1.68893 ν1 = 31.1 r2 = 0.60114 d2 = 0.1591 r3 = 44.8368 d3 = 0.0281 N2 = 1.62041 ν2 = 60.3 r4 = 1.1906 d4 = 0.0047 r5 = 0.78579 d5 = 0.1404 N3 = 1.69895 ν3 = 30.1 r6 = 9.49502 d6 = 0.9693 ˜ 0.0234 r7 = 0.65685 d7 = 0.0702 N4 = 1.6935 ν4 = 53.4 r8 = 21.5609 d8 = 0.0047 r9 = 0.52625 d9 = 0.0655 N5 = 1.6779 ν5 = 55.5 r10 = 0.96597 d10 = 0.1296 r11 = -4.79524 d11 = 0.04679 N6 = 1.80518 ν6 = 25.5 r12 = 0.41378 d12 = 0.1123 r13 = 1.48136 d13 = 0.131 N7 = 1.61293 ν7 = 37.0 r14 = -0.99788 ______________________________________ where r, d, N and ν, respectively, designate the radii of curvature of the refracting surfaces, the axial air separations or thickness of lenses, the refractive indices for the sodium d-line and the Abbe dispersion numbers numbered by subscripts in order from front to rear.

Claim 7

A zoom lens system as defined in claim 3 wherein the following conditions are satisfied ______________________________________ r1 = 0.9525 d1 = 0.0348 N1 = 1.62374 ν1 = 47.0 r2 = 0.464 d2 = 0.1993 r3 = -3.0373 d3 = 0.0261 N2 = 1.62041 ν2 = 60.3 r4 = 1.05166 d4 = 0.0043 r5 = 0.71438 d5 = 0.1042 N3 = 1.7452 ν3 = 38.3 r6 = 3.7443 d6 = 0.8247 ˜ 0.0226 r7 = 0.97824 d7 = 0.0695 N4 = 1.6779 ν4 = 55.5 r8 = -6.2048 d8 = 0.0043 r9 = 0.57913 d9 = 0.0869 N5 = 1.6779 ν5 = 55.5 r10 = 1.78711 d10 = 0.1042 r11 = -2.64838 d11 = 0.0261 N6 = 1.74077 ν6 = 27.7 r12 = 0.49925 d12 = 0.1303 r13 = 7.00545 d13 = 0.1216 N7 = 1.6393 ν7 = 45.0 r14 = -0.78971 ______________________________________ where r, d, N and ν, respectively, designate the radii of curvature of the refracting surfaces, the axial air separations or thickness of lenses, the refractive indices for the sodium d-line and the Abbe dispersion numbers numbered by subscripts in order from front to rear.

Claim 8

A zoom lens system as defined in claim 3 wherein the following conditions are satisfied ______________________________________ r1 = 3.38718 d1 = 0.0375 N1 = 1.76182 ν1 = 26.5 r2 = 0.63783 d2 = 0.1464 r3 = 29.2632 d3 = 0.0375 N2 = 1.62041 ν2 = 60.3 r4 = 1.39693 d4 = 0.0047 r5 = 0.86101 d5 = 0.1406 N3 = 1.80518 ν3 = 25.5 r6 = 8.80946 d6 = 0.9553 ˜ 0.02335 r7 = 0.86959 d7 = 0.0703 N4 = 1.6935 ν4 = 53.4 r8 = -7.93387 d8 = 0.0047 r9 = 0.58749 d9 = 0.0656 N5 = 1.6935 ν5 = 53.4 r10 = 1.81402 d10 = 0.1326 r11 = -2.42907 d11 = 0.0656 N6 = 1.80518 ν6 = 25.5 r12 = 0.47918 d12 = 0.1125 r13 = -182.0764 d13 = 0.0894 N7 = 1.59551 ν7 = 39.2 r14 = -0.68097 ______________________________________ where r, d, N and ν, respectively, designate the radii of curvature of the refracting surfaces, the axial air separations or thickness of lenses, the refractive indices for the sodium d-line and the Abbe dispersion numbers numbered by subscripts in order from front to rear.