Copying lens system

Claim 2

A copying lens system comprising, in succession from the object side, a first biconvex positive lens, a first biconcave negative lens, a diaphragm, a second biconcave negative lens identical to said first biconcave negative lens, and a second biconvex positive lens identical to said first biconvex positive lens, said system satisfying the following conditions: 0.298F <f.sub.1 <0.378F -0.41F <f.sub.2 <-0.312F 1.54<r.sub.2 /r.sub.3 <2.38 0.064<N.sub.1 -N.sub.2 <0.146 where F: the focal length of the entire lens system f 1 : the focal length of the first and second biconvex positive lenses f 2 : the focal length of the first and second biconcave negative lenses r 2 /r 3 : the ratio of curvature radii of the adjacent surfaces of the biconvex positive lens and the biconcave negative lens N 1 -N 2 : difference between the refractive index of the biconvex positive lens and the refractive index of the biconcave negative lens

Claim 3

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.31691 d.sub.1 = d.sub.7 = 0.0544 r.sub.2 = -r.sub.7 = -0.96330 d.sub.2 = d.sub.6 = 0.0208 r.sub.3 = -r.sub.6 = -0.46932 d.sub.3 = d.sub.5 = 0.0134 r.sub.4 = -r.sub.5 = 0.41820 d.sub.4 = 0.0276 N.sub.1 = N.sub.4 = 1.6935 ν.sub.1 = ν.sub.4 = 53.2 f.sub.1 = 0.350 f.sub.2 = -0.378 N.sub.2 = N.sub.3 = 1.58144 ν.sub.2 = ν.sub.3 = 40.7 r.sub. 2 /r.sub.3 = 2.053 N.sub.1 - N.sub.2 = 0.112 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 4

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.33348 d.sub.1 = d.sub.7 = 0.0570 r.sub.2 = -r.sub.7 = -0.94949 d.sub.2 = d.sub.6 = 0.0195 r.sub.3 = -r.sub.6 = -0.48473 d.sub.3 = d.sub.5 = 0.0147 r.sub.4 = -r.sub.5 = 0.44655 d.sub.4 = 0.0339 N.sub.1 = N.sub.4 = 1.6935 ν.sub.1 = ν.sub.4 = 53.2 f.sub.1 = 0.363 f.sub.2 = -0.397 N.sub.2 = N.sub.3 = 1.58144 ν.sub.2 = ν.sub.3 = 40.7 r.sub.2 /r.sub.3 = 1.959 N.sub.1 -N.sub.2 = 0.112 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 5

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.34435 d.sub.1 = d.sub.7 = 0.0550 r.sub.2 = -r.sub.7 = -1.07109 d.sub.2 = d.sub.6 = 0.0181 r.sub.3 = -r.sub.6 = -0.52128 d.sub.3 = d.sub.5 = 0.0260 r.sub.4 = -r.sub.5 = 0.42581 d.sub.4 = 0.0183 N.sub.1 = N.sub.4 = 1.726 ν.sub.1 = ν.sub.4 = 53.5 f.sub.1 = 0.365 f.sub.2 = -0.399 N.sub.2 = N.sub.3 = 1.58144 ν.sub.2 = ν.sub.3 = 40.7 r.sub. 2 /r.sub.3 = 2.055 N.sub.1 -N.sub.2 = 0.145 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 6

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.29039 d.sub.1 = d.sub.7 = 0.0544 r.sub.2 = -r.sub.7 = -0.76262 d.sub.2 = d.sub.6 = 0.0233 r.sub.3 = -r.sub.6 = -0.40310 d.sub.3 = d.sub.5 = 0.0051 r.sub.4 = -r.sub.5 = 0.41535 d.sub.4 = 0.0377 N.sub.1 = N.sub.4 = 1.6485 ν.sub.1 = ν.sub.4 = 53. f.sub.1 = 0.331 f.sub.2 = -0.351 N.sub.2 = N.sub.3 = 1.58144 ν.sub.2 = ν.sub.3 = 40.7 r.sub.2 /r.sub.3 = 1.892 N.sub.1 -N.sub.2 = 0.067 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 7

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.29321 d.sub.1 = d.sub.7 = 0.0414 r.sub.2 = -r.sub.7 = -1.03458 d.sub.2 = d.sub.6 = 0.0176 r.sub.3 = -r.sub.6 = -0.47557 d.sub.3 = d.sub.5 = 0.0107 r.sub.4 = -r.sub.5 = 0.36869 d.sub.4 = 0.0285 N.sub.1 = N.sub.4 = 1.691 ν.sub.1 = ν.sub.4 = 54.8 f.sub.1 = 0.335 f.sub.2 = -0.364 N.sub.2 = N.sub.3 = 1.56732 ν.sub.2 = ν.sub.3 = 42.8 r.sub.2 /r.sub.3 = 2.175 N.sub.1 -N.sub.2 = 0.124 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 8

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.33271 d.sub.1 = d.sub.7 = 0.0548 r.sub.2 = -r.sub.7 = -1.10922 d.sub.2 = d.sub.6 = 0.0317 r.sub.3 = -r.sub.6 = -0.46931 d.sub.3 = d.sub.5 = 0.0075 r.sub.4 = -r.sub.5 = 0.50650 d.sub.4 = 0.0398 N.sub.1 = N.sub.4 = 1.6935 ν.sub.1 = ν.sub.4 = 53.2 f.sub.1 = 0.375 f.sub.2 = -0.408 N.sub.2 = N.sub.3 = 1.59551 ν.sub.2 = ν.sub.3 = 39.2 r.sub. 2 /r.sub.3 = 2.364 N.sub.1 -N.sub.2 = 0.098 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 9

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.30394 d.sub.1 = d.sub.7 = 0.0555 r.sub.2 = -r.sub.7 = -0.69051 d.sub.2 = d.sub.6 = 0.0132 r.sub.3 = -r.sub.6 = -0.44054 d.sub.3 = d.sub.5 = 0.0169 r.sub.4 = -r.sub.5 = 0.37475 d.sub.4 = 0.0318 N.sub.1 = N.sub.4 = 1.72 ν.sub.1 = ν.sub.4 = 43.7 f.sub.1 = 0.300 f.sub.2 = -0.314 N.sub.2 = N.sub.3 = 1.6398 ν.sub.2 = ν.sub.3 = 34.5 r.sub.2 /r.sub.3 = 1.567 N.sub.1 -N.sub.2 = 0.080 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.

Claim 10

A copying lens system according to claim 1, satisfying the following data: ______________________________________ r.sub.1 = -r.sub.8 = 0.31041 d.sub.1 = d.sub.7 = 0.0587 r.sub.2 = -r.sub.7 = -0.85931 d.sub.2 = d.sub.6 = 0.0123 r.sub.3 = -r.sub.6 = -0.49107 d.sub.3 = d.sub.5 = 0.0105 r.sub.4 = -r.sub.5 = 0.37531 d.sub.4 = 0.0303 N.sub.1 = N.sub.4 = 1.744 ν.sub.1 = ν.sub.4 = 44.7 f.sub.1 = 0.313 f.sub.2 = -0.333 N.sub.2 = N.sub.3 = 1.63636 ν.sub.2 = ν.sub.3 = 35.4 r.sub.2 /r.sub.3 = 1.750 N.sub.1 -N.sub.2 = 0.108 ______________________________________ where r i represents the curvature radius of the ith lens surface as counted from the object side, d i represents the axial thickness or the axial air space between the ith lens surface and the i+1th lens surface, N i represents the refractive index of the ith lens, and ν i represents the dispersion value of the ith lens.