Large aperture telephoto lens system

Claim 1

A large aperture telephoto lens system comprising a front lens group and a rear lens group wherein said front lens group comprises a first positive meniscus lens, a second positive meniscus lens, a third positive meniscus lens and a fourth negative meniscus lens, and said rear lens group comprises a fifth thick negative meniscus lens with its concave surface positioned on the object side and a sixth positive lens, and said large aperture telephoto lens system having the following numerical data: ______________________________________ f=100, F/2.0 r.sub.1 = 41.623 d.sub.1 =7.00 n.sub.1 =1.62041 ν.sub.1 =60.27 r.sub.2 = 119.125 d.sub.2 =0.16 r.sub.3 = 36.34 d.sub.3 =5.50 n.sub.2 =1.6223 ν.sub.2 =53.2 r.sub.4 = 68.521 d.sub.4 =0.16 r.sub.5 = 30.05 d.sub.5 =5.00 n.sub.3 =1.62041 ν.sub.3 =60.27 r.sub.6 = 49.039 d.sub.6 =3.78 r.sub.7 = 70.094 d.sub.7 =2.20 n.sub.4 =1.78472 ν.sub.4 =25.71 r.sub.8 = 18.224 d.sub.8 =20.00 r.sub.9 = -44.400 d.sub.9 =9.49 n.sub.5 =1.64769 ν.sub.5 =33.8 r.sub.10 = -74.931 d.sub.10 =0.20 r.sub.11 = 100.258 d.sub.11 =3.51 n.sub.6 =1.7552 ν.sub.6 =27.51 r.sub.12 = -216.912 ______________________________________ wherein the reference symbols represent as follows: r 1 through r 12 : radii of curvature on the surfaces of the first through sixth lenses d 1 through d 11 : thicknesses of said lenses and air spaces therebetween n 1 through n 6 : refractive indices of said lenses ν 1 through ν 6 : Abbe's numbers of said lenses.