Compact wide angle lens

Claim 2

A compact wide angle lens system having an angle of view of 60°-70° and a total length as short as the total focal length, f, of the lens system, comprising, in succession from the object side, a first positive meniscus lens component having its convex surface facing the object side, a second biconcave lens component, a third positive lens component having its surface of sharper curvature facing the object side, a fourth positive lens component, and a fifth negative meniscus lens component having its convex surface facing the image side, the lens system satisfying the condition: 0.51f<f.sub.4 <1.38f where f 4 represents the focal length of said fourth component.

Claim 3

A compact wide angle lens system according to claim 1, further satisfying the following conditions: 0.57<f.sub.1 <0.74f d.sub.8 <0.15f 0.02f<d.sub.6 <0.12f where f 1 represents the focal length of said first component, d 6 represents the air space between said third component and said fourth component, and d 8 represents the air space between said fourth component and said fifth component.

Claim 4

A compact wide angle lens system according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62° ______________________________________ r.sub.1 = 33.422 d.sub.1 = 8.570 n.sub.1 = 1.77279 ν.sub.1 = 49.4 L.sub.1 r.sub.2 = 86.715 d.sub.2 = 5.713 r.sub.3 = -193.623 d.sub.3 = 2.857 n.sub.2 = 1.78470 ν.sub.2 = 26.1 L.sub.2 r.sub.4 = 44.440 d.sub.4 = 4.571 r.sub.5 = 38.296 d.sub.5 = 9.998 n.sub.3 = 1.62374 ν.sub.3 = 47.0 L.sub.3 r.sub.6 = 108.753 d.sub.6 = 4.285 r.sub.7 = 92.359 d.sub.7 = 11.141 n.sub.4 = 1.80740 ν.sub.4 = 35.4 L.sub.4 r.sub.8 = -131.181 d.sub.8 = 12.283 r.sub.9 = -22.687 d.sub.9 = 2.857 n.sub.5 = 1.78797 ν.sub.5 = 47.5 L.sub.5 r.sub.10 = -42.682 Σd = 62.274 wherein: Back focal length: Bf = 40.415 Total length: T.L. = 102.689 = 1.027f f.sub.1 = 65.8 = 0.658f f.sub.4 = 68.7 = 0.687f f.sub.12 = -539.6 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and ν represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f 12 represents the combined focal length of the first and second components.

Claim 5

A compact wide angle lens system according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62° ______________________________________ r.sub.1 = 32.280 d.sub.1 = 8.570 n.sub.1 = 1.77279 ν.sub.1 = 49.4 L.sub.1 r.sub.2 = 76.797 d.sub.2 = 5.713 r.sub.3 = -203.021 d.sub.3 = 2.857 n.sub.2 = 1.78470 ν.sub.2 = 26.1 L.sub.2 r.sub.4 = 42.069 d.sub.4 = 4.571 r.sub.5 = 36.999 d.sub.5 = 9.998 n.sub.3 = 1.62374 ν.sub.3 = 47.0 L.sub.3 r.sub.6 = -8133.457 d.sub.6 = 9.141 r.sub.7 = 100.449 d.sub.7 = 5.428 n.sub.4 = 1.80740 ν.sub.4 = 35.4 L.sub.4 r.sub.8 = -592.361 d.sub. 8 = 10.284 r.sub.9 = -22.130 d.sub.9 = 2.857 n.sub.5 = 1.78797 ν.sub.5 = 47.5 L.sub.5 r.sub.10 = -40.439 Σd = 59.417 wherein: Back focal length: Bf = 40.387 Total length: T.L. = 99.804 = 0.998f f.sub.1 = 66.5 = 0.665f f.sub.4 = 106.7 = 1.067f f.sub.12 = -388.0 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and ν represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f 12 represents the combined focal length of the first and second components.

Claim 6

A compact wide angle lens according to claim 2, wherein numerical data are as follows: ______________________________________ Focal length f = 100, F = 2.8, Angle of view = 62° ______________________________________ r.sub.1 = 32.565 d.sub.1 = 8.570 n.sub.1 = 1.78100 ν.sub.1 = 44.5 L.sub.1 r.sub.2 = 74.220 d.sub.2 = 5.713 r.sub.3 = -204.935 d.sub.3 = 2.875 n.sub.2 = 1.78472 ν.sub.2 = 25.7 L.sub.2 r.sub.4 = 42.997 d.sub.4 = 4.571 r.sub.5 = 38.167 d.sub.5 = 2.857 n.sub.3 = 1.62374 ν.sub.3 = 47.0 L.sub.3 r'.sub.5 = 30.280 d'.sub.5 = 7.142 n.sub.4 = 1.62230 ν'.sub.3 = 53.1 r.sub.6 = -2093.039 d.sub.6 = 7.999 r.sub.7 = 105.514 d.sub.7 = n.sub.5 = 1.79504 ν.sub.4 = 28.4 L.sub.4 r.sub.8 = -458.112 d.sub.8 = 10.284 r.sub.9 = -22.159 d.sub.9 = 2.857 n.sub.6 = 1.78797 ν.sub.5 = 47.5 L.sub.5 r.sub.10 = -39.381 Σd = 61.417 wherein: Back focal length: Bf = 40.223 Total length: T.L = 101.640 = 1.016f f.sub.1 = 68.1 = 0.681f f.sub.4 = 108.6 = 1.086f f.sub.12 = -374.9 ______________________________________ and wherein L represents a lens component, r represents the radius of curvature of a lens surface, d represents the center thickness of and the air space between respective lenses, n and ν represent refractive index and Abbe number, respectively, the subscripts represent order from the object side, and f 12 represents the combined focal length of the first and second components.

Claim 7

A compact wide angle lens system according to claim 1, wherein the second lens component is formed of high dispersion flint glass.