Behind-stop type lens system for photographic cameras

Claim 2

A behind-stop type lens system for photographic cameras comprising a first positive meniscus lens component having a convex surface on the object side, a second biconcave lens component and a third cemented doublet component consisting of a biconvex lens element and a negative lens element, and said lens system satisfying the conditions enumerated hereunder: (1) 0.23f<Σd<0.28f (2) 0.55<f 1 <0.59f. (3) -0.37f<f 2 <-0.32f (4) n 1 >1.71 (5) n 2 <1.67 (6) |r 7 |>4.8f (7) 0.26f<-r 6 <0.34f (8) |r 3 |/r 4 >6.0 (9) ν 1 -ν 2 >14 wherein the reference symbol Σd represents total length of said lens system as a whole, the reference symbols f 1 , f 2 and f designate focal lengths of the first, second lens components and the lens system as a whole respectively, the reference symbols n 1 and n 2 denote refractive indices of the first and second lens components respectively, the reference symbols r 3 and r 4 represent radii of curvature on the respective surfaces of the second lens component, the reference symbols r 6 and r 7 designate radii of curvature on the cemented surface and image side surface respectively of the third lens component and the reference symbols ν 1 and ν 2 denote Abbe's numbers of the first and second lens components respectively.

Claim 3

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2706 d.sub.1 = 0.665 n.sub.1 = 1.7432 ν.sub.1 = 49.41 r.sub.2 = 0.6699 d.sub.2 = 0.0268 r.sub.3 = -2.4418 d.sub.2 = 0.0379 n.sub.2 = 1.64769 ν.sub.2 = 33.80 r.sub.4 = 0.2512 d.sub.4 = 0.0330 r.sub.5 = 0.5771 d.sub.5 = 0.0771 n.sub.3 = 1.713 ν.sub.3 = 53.89 r.sub.6 = -0.3233 d.sub.6 = 0.0241 n.sub.4 = 1.51454 ν.sub.4 = 54.69 r.sub.7 = -9.5575 f.sub.1 = 0.570, f.sub.2 = -0.350 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 4

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2713 d.sub.1 = 0.0652 n.sub.1 = 1.757 ν.sub.1 = 47.87 r.sub.2 = 0.6668 d.sub.2 = 0.0250 r.sub.3 = -2.4513 d.sub.3 = 0.0365 n.sub.2 = 1.6668 ν.sub.2 = 33.04 r.sub.4 = 0.2581 d.sub.4 = 0.0317 r.sub.5 = 0.6213 d.sub.5 = 0.0766 n.sub.3 = 1.735 ν.sub.3 = 49.82 r.sub.6 = -0.3200 d.sub.6 = 0.0241 n.sub.4 = 1.5407 ν.sub.4 = 47.20 r.sub.7 = -5.0209 f.sub.1 = 0.564, f.sub.2 = -0.348 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 5

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2754 d.sub.1 = 0.0664 n.sub.1 = 1.757 ν.sub.1 = 47.87 r.sub.2 = 0.6949 d.sub.2 = 0.0268 r.sub.3 = -2.4583 d.sub.3 = 0.0379 n.sub.2 = 1.6668 ν.sub.2 = 33.04 r.sub.4 = 0.2590 d.sub.4 = 0.0331 r.sub.5 = 0.6218 d.sub.5 = 0.0778 n.sub.3 = 1.735 ν.sub.3 = 49.82 r.sub.6 = -0.3202 d.sub.6 = 0.0248 n.sub.4 = 1.5407 ν.sub.4 = 47.20 r.sub.7 = -5.6510 f.sub.1 = 0.564, f.sub.2 = -0.349 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 6

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2779 d.sub.1 = 0.0672 n.sub.1 = 1.757 ν.sub.1 = 47.87 r.sub.2 = 0.7134 d.sub.2 = 0.0281 r.sub.3 = -2.4998 d.sub.3 = 0.0389 n.sub.2 = 1.6668 ν.sub.2 = 33.04 r.sub.4 = 0.2592 d.sub.4 = 0.0343 r.sub.5 = 0.6230 d.sub.5 = 0.0787 n.sub.3 = 1.735 ν.sub.3 = 49.82 r.sub.6 = -0.3220 d.sub.6 = 0.0253 n.sub.4 = 1.5407 ν.sub.4 = 47.20 r.sub.7 = -6.0291 f.sub.1 = 0.546, f.sub.2 = -0.350 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 7

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 68° r.sub.1 = 0.2715 d.sub.1 = 0.0716 n.sub.1 = 1.74320 ν.sub.1 = 49.41 r.sub.2 = 0.6636 d.sub.2 = 0.0219 r.sub.3 = -2.3845 d.sub.3 = 0.0374 n.sub.2 = 1.64769 ν.sub.2 = 33.80 r.sub.4 = 0.2558 d.sub.4 = 0.0316 r.sub.5 = 0.6060 d.sub.5 = 0.0779 n.sub.3 = 1.713 ν.sub.3 = 53.89 r.sub.6 = -0.3307 d.sub.6 = 0.0250 n.sub.4 = 1.51451 ν.sub.4 = 54.69 r.sub.7 = -4.9283 f.sub.1 = 0.574, f.sub.2 = -0.355 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 8

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2734 d.sub.1 = 0.0716 n.sub.1 = 1.74320 ν.sub.1 = 49.41 r.sub.2 = 0.6849 d.sub.2 = 0.0220 r.sub.3 = -2.2708 d.sub.3 = 0.0376 n.sub.2 = 1.64769 ν.sub.2 = 33.80 r.sub.4 = 0.2561 - d.sub.4 = 0.0318 r.sub.5 = 0.6077 d.sub.5 = 0.0781 n.sub.3 = 1.713 ν.sub.3 = 53.89 r.sub.6 = -0.3183 d.sub.6 = 0.0250 n.sub.4 = 1.51823 ν.sub.4 = 58.96 r.sub.7 = -5.4917 f.sub.1 = 0.570, f.sub.2 = -0.353 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.

Claim 9

A behind-stop type lens system for photographic cameras according to claim 1 having the following numerical data: ______________________________________ f = 1.0 F/3.5 2ω = 65° r.sub.1 = 0.2669 d.sub.1 = 0.0703 n.sub.1 = 1.7432 ν.sub.1 = 49.41 r.sub.2 = 0.6460 d.sub.2 = 0.0216 r.sub.3 = -2.4561 d.sub.3 = 0.0397 n.sub.2 = 1.64769 ν.sub.2 = 33.80 r.sub.4 = 0.2468 d.sub.4 = 0.0303 r.sub.5 = 0.5589 d.sub.5 = 0.0731 n.sub.3 = 1.713 ν.sub.3 = 53.89 r.sub.6 = -0.3148 d.sub.6 = 0.0213 n.sub.4 = 1.51823 ν.sub.4 = 58.96 r.sub.7 = -12.9131 f.sub.1 = 0.567, f.sub.2 = -0.344 ______________________________________ wherein the reference symbols r 1 through r 7 represent radii of curvature on the respective surfaces of the lens elements, the reference symbols d 1 through d 6 designate thicknesses of the respective lens elements and airspaces therebetween, the reference symbols n 1 through n 4 denote refractive indices of the respective lens elements and the reference symbols ν 1 through ν 4 represent Abbe's numbers of the respective lens elements.