Large aperture ratio wide-angle photographic lens system

Claim 2

A large aperture ratio wide-angle photographic lens system consisting of, in the order from the object side, a first lens group comprising a negative lens component and a positive lens component, a second lens group comprising a lens component, which comprises at least one negative lens element and has negative refractive power as a whole, a positive lens component and a negative lens component, and a third lens group comprising a negative lens component, a positive lens component arranged as a cemented doublet, which consists of a negative lens element and a positive lens element, and a positive lens component, said large aperture ratio wide angle photographic lens system being arranged that a stop is located between said positive lens component in said second leng group and said third lens group and that an aspherical surface is provided near said stop, said large aperture ratio wide-angle photographic lens system having an aperture ratio of about F/1.4 and being further arranged to fulfill the following conditions: ##EQU3## where, reference symbol f represents the focal length of the lens system as a whole, reference symbol f I represents the total focal length of the first lens group, reference symbol f In represents the focal length of the negative lens component in the first lens group, reference symbol f IIp represents the focal length of the positive lens component in the second lens group, and reference symbol D represents the airspace between the negative lens component arranged on the object side in the second lens group and the positive lens component in the second lens group.

Claim 3

A large aperture ratio wide-angle photographic lens system according to claim 1 wherein said aspherical surface is formed on a plastic lens.

Claim 4

A large aperture ratio wide-angle photographic lens system according to claim 1 wherein said aspherical surface is formed by cementing an aspherical lens made of plastic material to a spherical lens made of glass material.

Claim 5

A large aperture ratio wide-angle photographic lens system according to claim 1 wherein said negative lens component located on the object side in said second lens group is arranged as a cemented doublet, which consists of a positive lens element and a negative lens element, and the surface on the object side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 212.7228 d.sub.1 = 10.7345 n.sub.1 = 1.58721 ν.sub.1 = 41.08 r.sub.2 = 90.7741 d.sub.2 = 52.7010 r.sub.3 = 984.8515 d.sub.3 = 18.6507 n.sub.2 = 1.58913 ν.sub.2 = 60.97 r.sub.4 = -484.2667 d.sub.4 = 0.3661 r.sub.5 = 196.7089 d.sub.5 = 18.3470 n.sub.3 = 1.80518 v.sub.3 = 25.43 r.sub.6 = -5584.2503 d.sub.6 = 11.1192 n.sub.4 = 1.58921 ν.sub.4 = 41.08 r.sub.7 = 72.3487 d.sub.7 = 34.6362 r.sub.8 = 105.8900 d.sub.8 = 28.8438 n.sub.5 = 1.71300 ν.sub.5 = 53.84 r.sub.9 = -161.2411 d.sub.9 = 0.5980 r.sub.10 = -1131.6585 d.sub.10 = 5.0159 n.sub.6 = 1.58921 ν.sub.6 = 41.08 r.sub.11 = 153.2492 d.sub.11 = 12.0409 r.sub.12 = ∞ (stop) d.sub.12 = 15.4852 r.sub.13 = -151.8295 (aspherical surface) d.sub.13 = 8.1081 n.sub.7 = 1.51742 ν.sub.7 = 52.41 r.sub.14 = ∞ d.sub.14 = 14.3342 r.sub.15 = -101.5101 d.sub.15 = 5.2589 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.16 = 250.1086 d.sub.16 = 26.7816 n.sub.9 = 1.81600 ν.sub.9 = 46.62 r.sub.17 = -82.7431 d.sub.17 = 0.3581 r.sub.18 = 921.0977 d.sub. 18 = 14.2882 n.sub.10 = 1.81600 ν.sub.10 = 46.62 r.sub.19 = -184.3846 f = 100, f.sub.I = -697.73, f.sub.In = -277.804 f.sub.IIp = 93.861, D = d.sub.7 = 34.6362 E = -0.79764 × 10.sup.-6, F = -0.93688 × 10.sup.-10 G = -0.78646 × 10.sup.-15, H = -0.32028 × 10.sup.-17 log|E| = -6.10 ##STR1## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 6

A large aperture ratio wide-angle photographic lens system according to claim 2 wherein said negative lens component located on the object side in said second lens group is arranged as a cemented doublet, which consists of a positive lens element and a negative lens element, and the surface on the object side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 211.3640 d.sub.1 = 10.6196 n.sub.1 = 1.58875 ν.sub.1 = 51.18 r.sub.2 = 88.6519 d.sub.2 = 52.5418 r.sub.3 = 513.1778 d.sub.3 = 18.8774 n.sub.2 = 1.58875 ν.sub.2 = 51.18 r.sub.4 = -486.5498 d.sub.4 = 0.3622 r.sub.5 = 271.7749 d.sub.5 = 18.3096 n.sub.3 = 1.80518 ν.sub.3 = 25.43 r.sub.6 = -2061.1302 d.sub.6 = 11.1279 n.sub.4 = 1.59551 ν.sub.4 = 39.21 r.sub.7 = 82.7968 d.sub.7 = 34.4311 r.sub.8 = 99.3778 d.sub.8 = 28.5352 n.sub.5 = 1.72000 ν.sub.5 = 46.03 r.sub.9 = - 173.1764 d.sub.9 = 0.5916 r.sub.10 = -2067.0856 d.sub.10 = 4.9348 n.sub.6 = 1.59551 ν.sub.6 = 39.21 r.sub.11 = 141.7259 d.sub.11 = 11.8978 r.sub.12 = ∞ (stop) d.sub.12 = 15.3023 r.sub.13 = -145.5991 (aspherical surface) d.sub.13 = 8.0338 n.sub.7 = 1.50400 ν.sub.7 = 52.00 r.sub.14 = ∞ d.sub.14 = 14.1870 r.sub.15 = -89.9779 d.sub.15 = 5.2039 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.16 = 270.7431 d.sub.16 = 27.2056 n.sub.9 = 1.81600 ν.sub.9 = 46.62 r.sub.17 = -81.6984 d.sub.17 = 0.3544 r.sub.18 = 2024.6124 d.sub.18 = 15.5461 n.sub.10 = 1.81600 ν.sub.10 = 46.62 r.sub.19 = -152.0902 f = 100, f.sub.I = -1084.463, f.sub.In = -267.952 f.sub.IIp = 91.718, D = d.sub.7 = 34.4311 E = -0.10442 × 10.sup.-5, F = -0.16473 × 10.sup.-9 G = 0.47666 × 10.sup.-14, H = -0.51029 × 10.sup.-17 log|E| = -5.98 ##STR2## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 7

A large aperture ratio wide-angle photographic lens system according to claim 2 wherein said negative lens component located on the object side in said second lens group is arranged as a cemented doublet, which consists of a positive lens element and a negative lens element, and the surface on the image side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 164.1239 d.sub.1 = 8.9717 n.sub.1 = 1.60311 ν.sub.1 = 60.70 r.sub.2 = 73.3433 d.sub.2 = 41.1573 r.sub.3 = 932.0756 d.sub.3 = 13.8050 n.sub.2 = 1.58267 ν.sub.2 = 46.33 r.sub.4 = -295.9703 d.sub.4 = 6.9013 r.sub.5 = 213.3130 d.sub.5 = 12.8309 n.sub.3 = 1.80518 ν.sub.3 = 25.43 r.sub.6 = 237.4965 d.sub.6 = 3.6139 n.sub.4 = 1.49831 ν.sub.4 = 65.03 r.sub.7 = 86.9413 d.sub.7 = 29.8399 r.sub.8 = 95.4424 d.sub.8 = 34.5090 n.sub.5 = 1.64250 ν.sub.5 = 58.37 r.sub.9 = -142.9065 d.sub.9 = 1.7284 r.sub.10 = ∞ (stop) d.sub.10 = 5.4955 r.sub.11 = 413.2088 d.sub.11 = 2.9224 n.sub.6 = 1.58904 ν.sub.6 = 53.20 r.sub.12 = 88.1594 d.sub.12 = 23.2212 r.sub.13 = -53.4586 d.sub.13 = 6.6922 n.sub.7 = 1.50400 ν.sub.7 = 52.00 r.sub.14 = -98.7747 (aspherical surface) d.sub.14 = 5.5373 r.sub.15 = -82.0987 d.sub.15 = 4.0442 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.16 = 340.9848 d.sub.16 = 25.2433 n.sub.9 = 1.77250 ν.sub.9 = 49.66 r.sub.17 = -78.4058 d.sub.17 = 0.3451 r.sub.18 = 1532.1063 d.sub.18 = 18.9786 n.sub.10 = 1.77250 ν.sub.10 = 49.66 r.sub.19 = -111.1287 f = 100, f.sub.I = -764.207, f.sub.In = -228.348 f.sub.IIp = 94.412, D = d.sub.7 = 29.8399 E = 0.88692 × 10.sup.-6, F = 0.22057 × 10.sup.-9 G = -0.10552 × 10.sup.-12, H = 0.31757 × 10.sup.-16 log|E| = -6.05 ##STR3## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lesnes, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 8

A large aperture ratio wide-angle photographic lens system according to claim 2 wherein said negative lens component located on the object side in said second lens group is arranged as a cemented doublet, which consists of a positive lens element and a negative lens element, and the surface on the image side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 156.0642 d.sub.1 = 11.2814 n.sub.1 = 1.61800 ν.sub.1 = 63.38 r.sub.2 = 89.4227 d.sub.2 = 52.0924 r.sub.3 = -466.0466 d.sub.3 = 13.8049 n.sub.2 = 1.48749 ν.sub.2 = 70.15 r.sub.4 = -240.7466 d.sub.4 = 6.9012 r.sub.5 = 228.5760 d.sub.5 = 17.9905 n.sub.3 = 1.80518 ν.sub.3 = 25.43 r.sub.6 = ∞ d.sub.6 = 8.5576 n.sub.4 = 1.66998 ν.sub.4 = 39.32 r.sub.7 = 96.7506 d.sub.7 = 47.5796 r.sub.8 = 94.3638 d.sub.8 = 25.1225 n.sub.5 = 1.81600 ν.sub.5 = 46.62 r.sub.9 = -255.3891 d.sub.9 = 0.7329 r.sub.10 = -12303.5912 d.sub.10 = 5.0454 n.sub.6 = 1.59270 ν.sub.6 = 35.29 r.sub.11 = 105.6125 d.sub.11 = 14.8167 r.sub.12 = ∞ (stop) d.sub.12 = 13.9409 r.sub.13 = -72.4298 d.sub.13 = 8.7730 n.sub.7 = 1.50400 ν.sub.7 = 52.00 r.sub.14 = -119.3873 (aspherical surface) d.sub.14 = 10.0162 r.sub.15 = -98.7983 d.sub.15 = 5.8771 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.16 = 356.3660 d.sub.16 = 25.2430 n.sub.9 = 1.77250 ν.sub.9 = 49.66 r.sub.17 = -94.6352 d.sub.17 = 0.3451 r.sub.18 = 23665.8076 d.sub.18 = 16.5630 n.sub.10 = 1.77250 ν.sub.10 = 49.66 r.sub.19 = -116.6842 f = 100, f.sub.I = -627.417, f.sub.In = -362.283 f.sub.IIp = 87.258, D = d.sub.7 = 47.5796 E = 0.97754 × 10.sup.-6, F = 0.12012 × 10.sup.-9 G = -0.34164 × 10.sup.-14, H = -0.52452 × 10.sup.-18 log|E| = -6.01 ##STR4## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 9

A large aperture ratio wide-angle photographic lens system according to claim 2 wherein said negative lens component located on the object side in said second lens group consists of a positive lens element and a negative lens element, and the surface on the image side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 242.7225 d.sub.1 = 10.7090 n.sub.1 = 1.62280 ν.sub.1 = 57.06 r.sub.2 = 95.0823 d.sub.2 = 44.6429 r.sub.3 = 1269.4171 d.sub.3 = 25.0188 n.sub.2 = 1.62230 ν.sub.2 = 53.20 r.sub.4 = -272.5227 d.sub.4 = 9.2857 r.sub.5 = 344.7205 d.sub.5 = 13.5714 n.sub.3 = 1.80518 ν.sub.3 = 25.43 r.sub.6 = -1839.8690 d.sub.6 = 3.5714 r.sub.7 = -466.1647 d.sub.7 = 5.8929 n.sub.4 = 1.66998 ν.sub.4 = 39.32 r.sub.8 = 103.5518 d.sub.8 = 27.5433 r.sub.9 = 92.8098 d.sub.9 = 26.2500 n.sub.5 = 1.81600 ν.sub.5 = 46.62 r.sub.10 = -241.6409 d.sub.10 = 0.5532 r.sub.11 = -735.4914 d.sub.11 = 5.4714 n.sub.6 = 1.58904 ν.sub.6 = 53.20 r.sub.12 = 129.7980 d.sub.12 = 14.0029 r.sub.13 = ∞ (stop) d.sub.13 = 18.8214 r.sub.14 = -76.2543 d.sub.14 = 8.2004 n.sub.7 = 1.50400 ν.sub.7 = 52.00 r.sub.15 = -97.1871 (aspherical surface) d.sub.15 = 8.9286 r.sub.16 = -80.7619 d.sub.16 = 5.6336 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.17 = 268.1878 d.sub.17 = 26.1268 n.sub.9 = 1.77250 ν.sub.9 = 49.66 r.sub.18 = -90.0288 d.sub.18 = 0.3571 r.sub.19 = -15386.1909 d.sub.19 = 18.6429 n.sub.10 = 1.81600 ν.sub.10 = 46.62 r.sub.20 = -116.8505 f = 100, f.sub.I = -1816.485, f.sub.In = -258.177 f.sub.IIp = 85.179, D = d.sub.8 = 27.5433 E = 0.96182 × 10.sup.-6, F = 0.15558 × 10.sup.-9 G = 0.91534 × 10.sup.-14, H = 0.57286 × 10.sup.-18 log|E| = -6.02 ##STR5## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference sybmols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 10

A large aperture ratio wide-angle photographic lens system according to claim 3 wherein said negative lens component located on the object side in said second lens group consists of a positive lens element and a negative lens element, and the surface on the image side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 236.3516 d.sub.1 = 10.7087 n.sub.1 = 1.65830 ν.sub.1 = 57.33 r.sub.2 = 96.0618 d.sub.2 = 44.6414 r.sub.3 = 1481.0757 d.sub.3 = 21.4279 n.sub.2 = 1.60311 ν.sub.2 = 60.70 r.sub.4 = -294.3310 d.sub.4 = 11.0711 r.sub.5 = 295.2622 d.sub.5 = 13.5710 n.sub.3 = 1.80518 ν.sub.3 = 25.43 r.sub.6 = -1769.0704 d.sub.6 = 3.5713 r.sub.7 = -612.1743 d.sub.7 = 5.8927 n.sub.4 = 1.66998 ν.sub.4 = 39.32 r.sub.8 = 97.1792 d.sub.8 = 27.5423 r.sub.9 = 92.9771 d.sub.9 = 26.2492 n.sub.5 = 1.81600 ν.sub.5 = 46.62 r.sub.10 = -255.1264 d.sub.10 = 0.5532 r.sub.11 = -1723.6643 d.sub.11 = 5.4713 n.sub.6 = 1.58904 ν.sub.6 = 53.20 r.sub.12 = 126.1655 d.sub.12 = 14.0024 r.sub.13 = ∞ (stop) d.sub.13 = 18.8208 r.sub.14 = -75.8547 d.sub.14 = 7.8569 n.sub.7 = 1.50137 ν.sub.7 = 56.40 r.sub.15 = -160.7198 d.sub.15 = 1.0714 n.sub.8 = 1.49216 ν.sub.8 = 57.50 r.sub.16 = -101.9118 (aspherical surface) d.sub.16 = 8.2140 r.sub.17 = -82.6970 d.sub.17 = 5.3570 n.sub.9 = 1.84666 ν.sub.9 = 23.88 r.sub.18 = 254.9063 d.sub.18 = 27.1420 n.sub.10 = 1.77250 ν.sub.10 = 49.66 r.sub.19 = -89.1108 d.sub.19 = 0.3571 r.sub.20 = 3033.6362 d.sub.20 = 17.8566 n.sub.11 = 1.81600 ν.sub.11 = 46.62 r.sub.21 = -125.5618 f = 100, f.sub.I = -995.402, f.sub.In = -253.526 f.sub.IIp = 86.438, D = d.sub.8 = 27.5423 E = 0.91718 × 10.sup.-6, F = 0.12071 × 10.sup.-9 G = 0.56621 × 10.sup.-14, H = 0.16151 × 10.sup.-17 log|E| = -6.04 ##STR6## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 11

A large aperture ratio wide-angle photographic lens system according to claim 1 wherein said negative lens component located on the object side in said second lens group consists of a negative single lens, said positive lens component in said second lens group consists of two positive lens elements, and the surface on the image side of said negative lens component in said third lens group is formed as an aspherical surface expressed by the formula shown below, said large aperture ratio wide-angle photographic lens system having the following numerical data: ______________________________________ r.sub.1 = 141.0631 d.sub.1 = 8.8880 n.sub.1 = 1.60311 ν.sub.1 = 60.70 r.sub.2 = 75.3180 d.sub.2 = 45.6606 r.sub.3 = -1379.1765 d.sub.3 = 14.3620 n.sub.2 = 1.54771 ν.sub.2 = 62.83 r.sub.4 = -219.4714 d.sub.4 = 3.5468 r.sub.5 = 598.1856 d.sub.5 = 5.2636 n.sub.3 = 1.58904 ν.sub.3 = 53.20 r.sub.6 = 126.0424 d.sub.6 = 37.4837 r.sub.7 = 96.5110 d.sub.7 = 11.1975 n.sub.4 = 1.81600 ν.sub.4 = 46.62 r.sub.8 = 144.3570 d.sub.8 = 7.5869 r.sub.9 = 130.5190 d.sub.9 = 20.3422 n.sub.5 = 1.81600 ν.sub.5 = 46.62 r.sub.10 = -206.9942 d.sub.10 = 0.8684 r.sub.11 = -502.7700 d.sub.11 = 5.0635 n.sub.6 = 1.63854 ν.sub.6 = 55.38 r.sub.12 = 116.9654 d.sub.12 = 11.6916 r.sub.13 = ∞ (stop) d.sub.13 = 17.5876 r.sub.14 = -72.6506 d.sub.14 = 9.4994 n.sub.7 = 1.51742 ν.sub.7 = 52.41 r.sub.15 = -90.6333 (aspherical surface) d.sub.15 = 10.2639 r.sub.16 = -69.3864 d.sub.16 = 5.9412 n.sub.8 = 1.84666 ν.sub.8 = 23.88 r.sub.17 = 314.2332 d.sub.17 = 25.2397 n.sub.9 = 1.77250 ν.sub.9 = 49.66 r.sub.18 = -82.6406 d.sub.18 = 0.3450 r.sub.19 = 2969.0568 d.sub.19 = 16.9676 n.sub.10 = 1.81600 ν.sub.10 = 46.62 r.sub.20 = -120.8530 f = 100, f.sub.I = -941.954, f.sub.In = -282.307 f.sub.IIp = 82.453, D = d.sub.6 = 37.4837 E = 0.90512 × 10.sup.-6, F = 0.31877 × 10.sup.-9 G = -0.13990 × 10.sup.-12, H = 0.49195 × 10.sup.-16 log|E| = -6.04 ##STR7## ______________________________________ where, reference symbols r 1 , r 2 , . . . respectively represent radii of curvature of respective lens surfaces, reference symbols d 1 , d 2 , . . . respectively represent thicknesses of respective lenses and airspaces between respective lenses, reference symbols n 1 , n 2 , . . . respectively represent refractive indices of respective lenses, reference symbols ν 1 , ν 2 , . . . respectively represent Abbe's numbers of respective lenses, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, . . . respectively represent coefficients of aspherical surface.

Claim 12

A large aperture ratio wide-angle photographic lens system comprising, in the order from the object side, a first lens group comprising a negative lens component, a second lens group comprising a lens component, which comprises at least one negative lens element and has negative refractive power as a whole, a positive lens component and a negative lens component, and a negative lens component, and a third lens group comprising a negative lens component, a positive lens component arranged as a cemented doublet, which consists of a negative lens element and a positive lens element, and a positive lens component, said large aperture ratio wide-angle photographic lens system being arranged that a stop is located between said positive lens component in said second lens group and said third lens group and that an aspherical surface is provided near said stop, said aspherical surface being defined by the following formula, and said large aperture ratio wide-angle photographic lens system having an aperture ratio of about F/1.4 and being further arranged to fulfill the following conditions: ##EQU4## where, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, respectively represent coefficients of aspherical surface and ##EQU5## where, reference symbol f represents the focal length of the lens system as a whole, reference symbol f 1 represents the total focal length of the first lens group, reference symbol f In represents the focal length of the negative lens component in the first lens group, reference symbol f IIp represents the focal length of the positive lens component in the second lens group, and reference symbol D represents the airspace between the negative lens component arranged on the object side in the second lens group and the positive lens component in the second lens group.

Claim 13

A large aperture ratio wide-angle photographic lens system comprising, in the order from the object side, a first lens group comprising a negative lens component, a second lens group comprising a lens component, which comprises at least one negative lens element and has negative refractive power as a whole, a positive lens component and a negative lens component, and a negative lens component, and a third lens group comprising a negative lens component, a positive lens component arranged as a cemented doublet, which consists of a negative lens element and a positive lens element, and a positive lens component, said large aperture ratio wide-angle photographic lens system being arranged that a stop is located between said positive lens component in said second lens group and said third lens group and that an aspherical surface is provided near said stop, said aspherical surface being defined by the following formula, and said large aperture ratio wide-angle photographic lens system having an aperture ratio of about F/1.4 and being further arranged to fulfill the following conditions: ##EQU4## where, reference symbol r represents the radius of curvature of the vertex portion of the aspherical surface, reference symbol x represents the distance from an arbitrary point on the aspherical surface to the tangential plane which is tangential to the aspherical surface at the vertex thereof, reference symbol y represents the distance from said arbitrary point to the optical axis, and reference symbols E, F, G, H, respectively represent coefficients of aspherical surface and ##EQU5## where, reference symbol f represents the focal length of the lens system as a whole, reference symbol f 1 represents the total focal length of the first lens group, reference symbol f In represents the focal length of the negative lens component in the first lens group, reference symbol f IIp represents the focal length of the positive lens component in the second lens group, and reference symbol D represents the airspace between the negative lens component arranged on the object side in the second lens group and the positive lens component in the second lens group.