High power wide-angle lens

Claim 1

A high power asymmetrical wide-angle lens having at least eight lens elements constituting at least five component groups predominantly air spaced from each other, said elements and groups including a condensing object-side front member (C) and a condensing image-side rear member (D) at front and rear respectively of a central vertex position, said elements and groups also including at least two negative meniscus groups (A and B) in front of said front condensing member (C) and having concave surfaces facing said front condensing member and at least one dispersing element behind said rear condensing member and having a concave surface facing said rear condensing member, said front condensing member (C) including a cemented surface which is convex toward said central vertex position, the index of refraction of the material on the rear side of said cemented surface being less than the index of refraction of the material on the forward side of said cemented surface, said rear condensing member (D) also including a cemented surface which is convex toward said central vertex position, the index of refraction of the material on the forward side of such cemented surface being less than the index of refraction of the material on the rear side of such cemented surface, the groups (A and B) in front of said front condensing member (C) including a member (B) separated by air space from said front condensing member and having the outer shape of a negative meniscus, the air space enclosed between said last mentioned member (B) and said front condensing member (C) forming a strongly dispersing air lens, the air lens power ( phi ) of which, as the sum of the powers of the two surfaces producing it, has a negative value greater than 0.490 Phi but not greater than 1.200 Phi , there also being an air space forming an air lens between said two groups (A and B) in front of said front condensing member, the sum of the refractive powers ( phi + phi phi , ) of said last mentioned air lens ( phi ) and said first mentioned air lens ( phi ) having a negative value greater than 0.605 Phi and not greater than 1.400 Phi , wherein Phi represents the equivalent refractive power of the entire lens system, the surface refractive power ( phi i) of the front surface (R1) of the entire lens system and the surface refractive power ( phi r) of the last rear outer surface (Rr) of the entire lens system being so chosen that the sum of said surface refractive powers ( phi i + phi r phi i,r) is greater than 1.290 Phi but not greater than 1.970 Phi .