Adapter lens system for use with photographic cameras

Claim 2

An adapter lens system for use with photographic cameras comprising a first positive lens element, a second biconcave lens element, and a third positive lens element and a stop arranged on the front side of said lens elements, said lens system satisfying the following condition: (1) f B >0.85f (2) L<0.35f (3) f 1 >0.5f (4) 0.06f≦d 3 (5) ν 1 <45 (6) d 5 ≧0.05f wherein the reference symbol L represents total length of said lens system as a whole, the reference symbol f B designates back focal length of said lens system, the reference symbol f 1 denotes focal length of said first lens element, the reference symbol f represents focal length of said lens system as a whole, the reference symbol d 3 designates airspace reserved between said first and second lens elements, the reference symbol d 5 denotes airspace reserved between said second and third lens elements and the reference symbol ν 1 represents Abbe's number of said first lens element.

Claim 3

An adapter lens system for use with photographic cameras according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 8.4128 r.sub.2 = 40.0974 d.sub.2 = 5.0477 n.sub.1 = 1.60342 ν.sub.1 = 38.01 r.sub.3 = ∞ d.sub.3 = 7.2199 r.sub.4 = -52.2462 d.sub.4 = 2.3556 n.sub.2 = 1.68893 ν.sub.2 =31.08 r.sub.5 = 40.1509 d.sub.5 = 8.9327 r.sub.6 = 111.5114 d.sub.6 = 5.0477 n.sub.3 = 1.62041 ν.sub.3 = 60.27 r.sub.7 = -38.5050 f = 100, object point 841.284, image height 13.461 f.sub.B = 94.864, L = 28.61, f.sub.1 = 66.45 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 3 designate the thicknesses of the respective lens elements and airspaces reserved between the respective lens elements, the reference symbols n 1 through n 3 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 3 represent Abbe's numbers of the respective lens elements.

Claim 4

An adapter lens system for use with photographic cameras according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 10.0365 r.sub.2 = 44.8883 d.sub.2 = 3.3680 n.sub.1 = 1.60717 ν.sub.1 = 40.26 r.sub.3 = ∞ d.sub.3 = 10.306 r.sub.4 = -38.2298 d.sub.4 = 3.7721 n.sub.2 = 1.64769 ν.sub.2 = 33.80 r.sub.5 = 38.2298 d.sub.5 = 6.1292 r.sub.6 = 80.4927 d.sub.6 = 5.0520 n.sub.3 = 1.58913 ν.sub.3 = 60.97 r.sub.7 = -31.1672 f = 100 object point 841.992, image height 13.472 f.sub.B = 94.891, L = 28.62, f.sub.1 = 73.93 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 6 designate the thicknesses of the respective lens elements and airspaces reserved between the respective lens elements, the reference symbols n 1 through n 3 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 3 represent Abbe's numbers of the respective lens elements.

Claim 5

An adapter lens system for use with photographic cameras according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 8.4110 r.sub.2 = 47.4856 d.sub.2 = 3.3644 n.sub.1 = 1.64769 ν.sub.1 = 33.80 r.sub.3 = ∞ d.sub.3 = 9.1478 r.sub.4 = -48.9170 d.sub.4 = 4.3722 n.sub.2 = 1.72825 ν.sub.2 = 28.46 r.sub.5 = 48.9170 d.sub.5 = 7.5075 r.sub.6 = 131.8984 d.sub.6 = 4.2055 n.sub.3 = 1.69680 ν.sub.3 = 55.52 r.sub.7 = -39.7164 f = 100, object point 841.0995, image height 13.458 f.sub.B = 94.815, L = 31.12, f.sub.1 = 73.32 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 6 designate the thicknesses of the respective lens elements and airspaces reserved between the respective lens elements, the reference symbols n 1 through n 3 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 3 represent Abbe's numbers of the respective lens elements.

Claim 6

An adapter lens system for use with photographic cameras according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 8.4189 r.sub.2 = 40.2970 d.sub.2 = 3.3676 n.sub.1 = 1.61293 ν.sub.1 = 37.00 r.sub.3 = ∞ d.sub.3 = 8.3588 r.sub.4 = -49.8022 d.sub.4 = 3.4457 n.sub.2 = 1.68893 ν.sub.2 = 31.08 r.sub.5 = 37.8875 d.sub.5 = 8.4009 r.sub.6 = 92.2409 d.sub.6 = 5.0514 n.sub.3 = 1.58913 ν.sub.3 = 60.97 r.sub.7 = -35.7511 f = 100, object point 841.89, image height 13.470 f.sub.B = 94.914, L = 28.62, f.sub.1 = 65.75 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 6 designate the thicknesses of the respective lens elements and airspaces reserved between the respective lens elements, the reference symbols n 1 through n 3 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 3 represent Abbe's numbers of the respective lens elements.

Claim 7

An adapter lens system for use with photograhic cameras according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 8.4222 r.sub.2 = 35.9119 d.sub.2 = 5.0533 n.sub.1 = 1.58144 ν.sub.1 = 40.75 r.sub.3 = 189.9936 d.sub.3 = 6.7377 r.sub.4 = -60.6219 d.sub.4 = 3.3689 n.sub.2 = 1.66680 ν.sub.2 = 33.04 r.sub.5 = 34.5753 d.sub.5 = 7.58 r.sub.6 = 71.9651 d.sub.6 = 6.7377 n.sub.3 = 1.62041 ν.sub.3 = 60.27 r.sub.7 = -41.5271 f = 100, object point 842.219, image height 13.476 f.sub.B = 96.455, L = 29.48, f.sub.1 = 75.25 ______________________________________ wherein the reference symbols r 1 through t 7 represent radii of curvature on the surfaces of the respective lens elements, the reference symbols d 1 through d 6 designate the thicknesses of the respective lens elements and airspaces reserved between the respective lens elements, the reference symbols n 1 through n 3 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 3 represent Abbe's numbers of the posiective lens elements.