Wide angle lens

Claim 2

A wide angle lens system comprising, in succession from the object side toward the image side: a divergent first lens group having its surface of smaller curvature facing the object side; a divergent, meniscus, second lens group having its convex surface facing the object side; said first and second lens groups defining therebetween a divergent, meniscus-shaped air chamber having its convex surface facing the object side; a convergent, meniscus, third lens group consisting of a plurality of lenses; a convergent, meniscus, fourth lens group consisting of a plurality of lenses; and a divergent, meniscus, fifth lens group having its convex surface facing the image side.

Claim 3

A wide angle lens system according to claim 1, wherein said third lens group is a cemented lens consisting of three elements.

Claim 4

A wide angle lens system according to claim 2, wherein the following conditions are satisfied: d.sub.11 < d.sub.4, (1) R2> R3 and (2) n.sub.3 > n.sub.4, (3) where d 11 is the air-spacing between said fourth and said fifth lens group, d 4 is the air spacing between said second and said third lens group, R2 is the radius of curvature of the lens surface of said first lens group which is adjacent to said divergent meniscus-shaped air chamber, R3 is the radius of curvature of the lens surface of said second lens group which is adjacent to said divergent meniscus-shaped air chamber, and n 3 and n 4 each are the refractive indices of the first and second lenses in said third lens group as viewed from the object side.

Claim 5

A wide angle lens system according to claim 1, wherein said fourth lens group is a cemented lens consisting of two elements.

Claim 6

A wide angle lens system according to claim 3, wherein the following condition is further satisfied: d.sub.11 < 0.5d.sub. 4

Claim 7

A wide angle lens system according to claim 3, wherein the following condition is further satisfied: 2R4> R3> R4, where R4 represents the radius of curvature of the lens surface of said second lens group which is adjacent to said third lens group.

Claim 8

A wide angle lens system according to claim 3, wherein said fourth lens group is a cemented lens consisting of two elements and the following conditions are further satisfied: ν d.sub.3 >ν d.sub.4 < νd.sub.5 and (1) ν d.sub.6 > νd.sub.7, (2) where ν d 3 , νd 4 and νd 5 each represent the dispersive power of the first, second and third lenses in said third lens group as viewed from the object side, and ν d 6 and ν d.sub. 7 represent the dispersive power of the first and second lenses in said fourth lens group as viewed from the object side.

Claim 9

A wide angle lens system according to claim 3, wherein data are as follows: ______________________________________ f = 100; B.f.=68.44; F/4.5; angle of view 100° R1= +896.667 d.sub.1 = 2.11 n.sub.1 = 1.51118 νd.sub.1 = 50.9 R2= +109.0 d.sub.2 = 0.11 R3= +42.889 d.sub.3 = 1.67 n.sub.2 = 1.61266 νd.sub.2 = 44.3 R4= +27.549 d.sub.4 = 23.67 R5= +34.1 d.sub.5 = 16.39 n.sub.3 = 1.79877 νd.sub.3 = 44.27 R6= -44.444 d.sub.6 = 2.67 n.sub.4 = 1.67163 νd.sub.4 = 38.8 R7= +36.167 d.sub.7 = 4.0 n.sub.5 = 1.51823 νd.sub.5 = 59.0 R8= +323.889 d.sub.8 = 3.89 R9= -R9=- d.sub.9 = 9.67 n.sub.6 = 1.48749 νd.sub.6 = 70.0 R10= -17.811 d.sub.10 32 13.06 n.sub.7 = 1.60342 νd.sub.7 =38.0 R11= -37.044 d.sub.11 = 7.67 R12= -20.944 d.sub.12 = 1.67 n.sub.8 = 1.60311 νd.sub.8 = 60.7 R13= -42.976 ______________________________________

Claim 10

A wide angle lens system according to claim 3, wherein data are as follows: ______________________________________ f = 100; B.f. = 66.49; F/4.5; angle of View 100° R1= =1248.0 d.sub.1 = 2.67 n.sub.1 = 1.54072 νd.sub.1 = 47.2 R2= +128.677 d.sub.2 = 0.93 R3= +46.533 d.sub.3 = 2.0 n.sub.2 = 1.61266 νd.sub.2 = 44.3 R4= +28.853 d.sub.4 = 24.8 R5= +35.067 d.sub.5 = 18.67 n.sub.3 = 1.79877 νd.sub.3 = 44.27 R6= -45.528 d.sub.6 = 1.4 n.sub.4 = 1.67163 νd.sub.4 = 38.8 R7= +39.6 d.sub.7 = 4.4 n.sub.5 = 1.51823 νd.sub.5 = 59.0 R8= +419.6 d.sub.8 = 4.67 R9= -186.67 d.sub.9 = 8.0 n.sub.6 = 1.48749 νd.sub.6 = 70.0 R10= -18.133 d.sub.10 = 14.13 n.sub.7 = 1.60342 νd.sub.7 = 38.0 R11= -40.533 d.sub.11 = 8.67 R12= -21.387 d.sub.12 = 2.13 n.sub.8 = 1.60311 νd.sub.8 = 60.7 R13= -42.363 ______________________________________

Claim 11

A wide angle lens system according to claim 3, wherein data are as follows: ______________________________________ f = 100; B.f. = 64.65; F/4; Angle of view 100° R1= ∞ d.sub.1 = 3.08 n.sub.1 = 1.51118 νd.sub.1 = 50.9 R2= +144.15 d.sub.2 = 4.15 R3= +46.154 d.sub.3 = 2.31 n.sub.2 = 1.61266 νd.sub.2 = 44.3 R4= +28.769 d.sub.4 = 22.15 R5= +35.138 d.sub.5 = 19.69 n.sub.3 = 1.79877 νd.sub.3 = 44.27 R6= -46.031 d.sub.6 = 1.23 n.sub.4 = 1.67163 νd.sub.4 = 38.8 R7= +42.0 d.sub.7 = 3.85 n.sub.5 = 1.52 νd.sub.5 = 70.1 R8= +386.15 d.sub.8 = 5.08 R9= -186.15 d.sub.9 = 8.31 n.sub.6 = 1.51835 νd.sub.6 = 60.3 R10= -18.4 d.sub.10 = 14.62 n.sub.7 = 1.61293 νd.sub.7 = 36.9 R11= -42.538 d.sub.11 = 7.69 R12= -21.554 d.sub.12 = 3.38 n.sub.8 = 1.62299 νd.sub.8 = 58.1 R13= -42.738 ______________________________________