Bright medium-range telephoto lens

Claim 2

A bright medium-range telephoto lens comprising, in order from an object, a first positive lens having a stronger positive power toward the object, a second positive-meniscus lens having a stronger positive power toward the object, a third negative-meniscus lens having a stronger negative power toward an image, a compound lens spaced from the third lens with an aperture interposed therebetween and having a fourth negative lens having a stronger negative power toward the object and a fifth positive lens having a stronger positive power toward the image, a sixth positive lens, and a seventh positive lens having a weak power, the bright medium-range telephoto lens meeting the following conditions: ##EQU3## where ri: the radius of curvature of the ith surface, di: the thickness of inter-lens distance of the ith lens, ni: the refractive index of the ith lens at d-line, νi: the Abbe number of the ith lens, and f 1 ,i : the focal length from the first surface to the ith surface.

Claim 3

The telephoto lens of claim 1 further meeting the following conditions: ##EQU4##

Claim 4

The telephoto lens of claim 1, further meeting the following charts: ______________________________________ 1:1.4 f = 84.91 ω = 14.3° f.sub.B = 39.89 No. r d n ν ______________________________________ 1 55.762 10.38 1.72916 54.7 2 571.681 0.15 3 40.623 10.15 1.72916 54.7 4 75.873 2.93 5 226.050 5.93 1.7552 27.5 6 25.294 21.42 7 -31.300 2.76 1.59551 39.2 8 273.800 7.81 1.77250 49.6 9 -39.091 0.15 10 87.610 3.26 1.77250 49.6 11 1080.030 1.40 12 4058.633 3.00 1.72916 54.7 13 -334.410 f/f.sub.1,2 = 1.010 f/f.sub.1,4 = 1.798 ##STR4## f/f.sub.1,6 = 0.443 f/f.sub.1,9 = 0.544 f/f.sub.1,11 = 0.906 ______________________________________ where r is the radius of curvature, d the lens thickness of inter-lens distance, n the refractive index at d-line, ν the Abbe number, f and ω are the focal length and half angle of view, respectively, when the object is at an infinite distance, and f B the back focus.

Claim 5

The telephoto lens of claim 1, further meeting the following charts: ______________________________________ 1:1.4 f = 84.96 ω = 14.3° f.sub.B = 40.38 No. r d n ν ______________________________________ 1 54.361 9.44 1.72916 54.7 2 558.468 0.15 3 38.904 9.60 1.64000 60.1 4 79.461 2.93 5 258.287 6.72 1.71736 29.5 6 24.080 22.39 7 -30.374 2.79 1.59551 39.2 8 151.072 7.13 1.77250 49.6 9 -37.474 0.15 10 89.776 2.78 1.77250 49.6 11 1583.604 1.36 12 ∞ 2.59 1.72916 54.7 13 -388.402 f/f.sub.1,2 = 1.037 f/f.sub.1,4 = 1.807 ##STR5## f/f.sub.1,6 = 0.425 f/f.sub.1,9 = 0.562 f/f.sub.1,11 = 0.925 ______________________________________ where r is the radius of curvature, d the lens thickness of inter-lens distance, n the refractive index at d-line, ν the Abbe number, f and ω are the focal length and half angle of view, respectively, when the object is at an infinite distance, and f B the back focus.

Claim 6

The telephoto lens of claim 1, further meeting the following charts: ______________________________________ 1:1.4 f = 84.77 ω = 14.3° f.sub.B = 39.37 No. r d n ν ______________________________________ 1 55.762 10.38 1.72916 54.7 2 571.681 0.15 3 39.700 10.15 1.69680 56.5 4 76.266 2.93 5 226.050 5.93 1.74000 28.3 6 24.898 21.42 7 -31.300 2.80 1.59551 39.2 8 220.000 7.60 1.77250 49.6 9 -39.000 0.15 10 87.61 3.26 1.77250 49.6 11 1188.661 1.4 12 4058.633 3.0 1.72916 54.7 13 -374.842 f/f.sub.1,2 = 1.009 f/f.sub.1,4 = 1.795 ##STR6## f/f.sub.1,6 = 0.449 f/f.sub.1,9 = 0.555 f/f.sub.1,11 = 0.916 ______________________________________ where r is the radius of curvature, d the lens thickness or inter-lens distance, n the refractive index at d-line, ν the Abbe number, f and ω are the focal length and half angle of view, respectively, when the object is at an infinite distance, and f B the back focus.