Bright wide-angle lens

摘要

PROBLEM TO BE SOLVED: To obtain a wide-angle lens which has excellent image-formation performance up to a peripheral viewing angle, whose viewing angle is wide, whose diameter is large and that is bright and is made compact by disposing a negative meniscus lens whose concave surface is faced to an object side and that at least one aspherical surface on a most object side. ;SOLUTION: A first lens L₁ consisting of the negative meniscus lens whose concave surface is faced to the object side and that has at least one aspherical surface, a second lens L₂ whose both surfaces are formed into a convex shape, a third lens L₃ whose both surfaces are formed into a concave shape, a fourth lens L₄ whose both surfaces are formed into the convex shape and a fifth lens L₅ consisting of the negative meniscus lens whose concave surface is faced to the object side and that has at least one aspherical surface are orderly disposed from the object side. Also, they satisfy an expression: -0.9(R₁-R₂)/(R₁+R₂). In the expression, R₁ means the radius of curvature of the surface of the first lens L₁ on the object side and R₂ means that of the surface of the first lens L₁ on an image surface side.;COPYRIGHT: (C)1999,JPO