Variable-power copying lens

Claim 2

A variable-power copying lens including, successively in order from an object, a first lens group having a positive focal length and a second lens group having a negative focal length, said first and second lens groups being movable in their entirety while varying an interval therebetween to keep constant the distance between an object surface and an image-focusing surface, characterized in that said first lens group comprises a first positive lens, a second negative lens, a third positive lens, a fourth negative lens, and a fifth positive lens, and said second lens group comprises a sixth positive-meniscus lens having a convex surface facing an image and a seventh negative-meniscus lens having a convex surface facing the image, said variable-power copying lens meeting the following conditions: ##EQU3## where f I : the focal length of the first positive lens group; f II : the focal length of the second negative lens group; f max : the focal length of the entire lens system at 1.00×; f i : the focal length of the ith lens from the object; N i , ν i : the refractive index at e line and Abbe number of the ith lens from the object.

Claim 3

A variable-power copying lens according to claim 1, wherein the lens further meets the following conditions: ##EQU4##

Claim 4

A variable-power copying lens according to claim 1 wherein the lens has the following characteristics: ______________________________________ r.sub.1 54.668 d.sub.1 6.97 N.sub.1 1.62287 ν.sub.1 60.3 r.sub.2 142.646 d.sub.2 2.47 r.sub.3 -1271.968 d.sub.3 3.00 N.sub.2 1.54345 ν.sub.2 47.2 r.sub.4 48.599 d.sub.4 9.99 r.sub.5 69.878 d.sub.5 7.06 N.sub.3 1.67000 ν.sub.3 48.3 r.sub.6 -127.660 d.sub.6 8.43 r.sub.7 -60.312 d.sub.7 2.50 N.sub.4 1.62409 ν.sub.4 36.3 r.sub.8 112.013 d.sub.8 8.83 r.sub.9 -806.748 d.sub.9 9.26 N.sub.5 1.65141 ν.sub.5 53.0 .sup. r.sub.10 -57.890 .sup. d.sub.10 5.00-20.28 .sup. r.sub.11 -87.535 .sup. d.sub.11 7.66 N.sub.6 1.61686 ν.sub.6 37.0 .sup. r.sub.12 -48.720 .sup. d.sub.12 4.76 .sup. r.sub.13 -47.979 .sup. d.sub.13 4.00 N.sub.7 1.70557 ν.sub.7 41.2 .sup. r.sub.14 -114.707 ______________________________________ where r i is the radius of curvature of the ith surface from the object and d i is the ith lens thickness or inter-lens interval from the object.

Claim 5

A variable-power copying lens according to claim 1 wherein the lens has the following characteristics: ______________________________________ r.sub.1 46.168 d.sub.1 4.23 N.sub.1 1.60548 ν.sub.1 60.7 r.sub.2 133.789 d.sub.2 2.16 r.sub.3 -666.586 d.sub.3 2.50 N.sub.2 1.54345 ν.sub.2 47.2 r.sub.4 44.700 d.sub.4 10.42 r.sub.5 69.752 d.sub.5 5.72 N.sub.3 1.70346 ν.sub.3 48.1 r.sub.6 -118.653 d.sub.6 7.22 r.sub.7 -55.070 d.sub.7 2.25 N.sub.4 1.62409 ν.sub.4 36.3 r.sub.8 105.470 d.sub.8 7.19 r.sub.9 -538.830 d.sub.9 7.41 N.sub.5 1.66152 ν.sub.5 50.9 .sup. r.sub.10 -52.737 .sup. d.sub.10 5.00-16.70 .sup. r.sub.11 -95.041 .sup. d.sub.11 6.96 N.sub.6 1.61686 ν.sub.6 37.0 .sup. r.sub.12 -44.695 .sup. d.sub.12 4.06 .sup. r.sub.13 -43.275 .sup. d.sub.13 4.00 N.sub.7 1.70557 ν.sub.7 41.2 .sup. r.sub.14 -130.527 ______________________________________ where r i is the radius of curvature of the ith surface from the object and d i is the ith lens thickness or inter-lens interval from the object.

Claim 6

A variable-power copying lens according to claim 1 wherein the lens has the following characteristics: ______________________________________ r.sub.1 47.915 d.sub.1 5.50 N.sub.1 1.64254 ν.sub.1 60.1 r.sub.2 137.919 d.sub.2 3.02 r.sub.3 -767.423 d.sub.3 2.50 N.sub.2 1.59911 ν.sub.2 39.2 r.sub.4 47.434 d.sub.4 11.53 r.sub.5 73.483 d.sub.5 5.57 N.sub.3 1.80401 ν.sub.3 42.2 r.sub.6 -128.317 d.sub.6 7.07 r.sub.7 -60.754 d.sub.7 2.25 N.sub.4 1.65407 ν.sub.4 39.4 r.sub.8 98.491 d.sub.8 8.56 r.sub.9 -443.401 d.sub.9 6.50 N.sub.5 1.64254 ν.sub.5 60.1 .sup. r.sub.10 -55.939 .sup. d.sub.10 2.00-16.18 .sup. r.sub.11 -99.604 .sup. d.sub.11 6.70 N.sub.6 1.59911 ν.sub.6 39.2 .sup. r.sub.12 -44.025 .sup. d.sub.12 3.17 .sup. r.sub.13 -43.207 .sup. d.sub.13 4.00 N.sub.7 1.70557 ν.sub.7 41.2 .sup. r.sub.14 -125.083 ______________________________________ where r i is the radius of curvature of the ith surface from the object and d i is the ith lens thickness or inter-lens interval from the object.

Claim 7

A variable-power copying lens according to claim 1, 2, 3, 4 or 5, wherein the object and image surfaces are interchanged.