Wide angle zoom lens

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less,
• said zoom lens being characterized in that said negative lens formed of the low-index high-dispersion material has a non-spherical surface in which the difference in thickness beteween the central portion and the marginal edge portion is small, in that when said non-spherical surface is approximated by ##EQU3## said zoom lens satisfies the following conditions for coefficients C.sub.8 and C.sub.10 :
• 0<.vertline.C.sub.8 .vertline.<0.025fw.times.10.sup.-7
• <.vertline. C.sub.10 .vertline.<0.05fw.times.10.sup.-9,
• where y is the distance from the optical axis, x is the distance from the tangential plane of the vertex of the non-spherical surface, C.sub.0 is the paraxial curvature (the inverse number of the radius of paraxial curvature) at the vertex of the non-spherical surface, C.sub.4 to C.sub.10 are the fourth-order, sixth-order, eighth-order and tenth-order non-spherical surface coefficients, and fw is the focal length of the lens system at the wide angle end thereof, in that the second negative lens from the object side in said divergent lens group has said non-spherical surface, in that said second negative lens is a negative meniscus lens having its convex surface facing the object side, and said non-spherical surface is that surface of said negative meniscus lens which is adjacent to the object side, and in that said zoom lens satisfies the following condition:
• 0.02<P.sub.2 /Pa<0.7
• where P.sub.2 is the refractive power of said negative meniscus lens and Pa is the refractive power of said divergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, three negative meniscus lenses having their convex surfaces facing the object side, and a positive lens, said convergent lens group has, in succession from the object side, a positive lens, a positive lens having a center thickness greater than that of the preceding positive lens, a biconcave negative lens, a positive meniscus lens having its convex surface facing the image side, and a biconvex positive lens, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.9.vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• .vertline.Pa.ve rtline., P.sub.1 <
• 0 0.02 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <0.6 .vertline.Pa.vertline., P.sub.2 <
• 0 0.4.vertline.Pa.vertline. <
• .vertline.P.sub.3 .vertline. <0.9 .vertline.Pa.vertline., P.sub.3 <
• 0 0.65 .vertline.Pa.vertline. <P.sub.4 <0.85 .vertline.Pa.vertline. 0.3Pb<P.sub.5 <0.5 Pb 0.7Pb<P.sub.6 <0.9 Pb 1.6Pb<
• .vertline.P.sub.7 .vertline. <2.4 Pb, P.sub.7 <
• 0 0.5Pb<P.sub.8 <1.6 Pb 0.4Pb<P.sub.9 <0.9 Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, two negative meniscus lenses having their convex surfaces facing the object side and a positive meniscus lens having its convex surface facing the object side, said convergent lens group has, in succession from the object side, a positive lens, a negative meniscus lens having its convex surface facing the object side, a biconvex positive lens, a biconcave negative lens, a positive meniscus lens having its convex surface facing the image side, and a positive lens, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.4.vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 1.1.vertline.Pa .vertline., P.sub.1 <
• 0 0.04 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.7.vertline. a.vertline., P.sub.2 <
• 0 0.05 .vertline.Pa.vertline. <P.sub.3 <
• 0.6.vertline.Pa.vertline. 0.4Pb<P.sub.4 <
• 0.9Pb -0.5Pb<P.sub.5 <
• 0.2Pb 1.1Pb<P.sub.6 <
• 1.9Pb 1.7Pb<
• .vertline.P.sub.7 .vertline. <
• 2.6Pb, P.sub.7 <
• 0 0.4Pb<P.sub.8 <
• 0.95Pb 0.35Pb<P.sub.9 <
• 0.8Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, two negative meniscus lenses having their convex surfaces facing the object side and a positive meniscus lens having its convex surface facing the object side, said convergent lens group has, in succession from the object side, a positive lens, a positive lens having a center thickness greater than that of the preceding positive lens, a biconcave negative lens, a positive meniscus lens having its convex surface facing the image side, and a biconvex positive lens, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.9 .vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 0.98 .vertline.Pa.vertline., P.sub.1 <
• 0 0.3 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.5.vertline.P a.vertline., P.sub.2 <
• 0 0.2 .vertline.Pa.vertline. <P.sub.3 <
• 0.35 .vertline.Pa.vertline. 0.3Pb<P.sub.4 <
• 1.3Pb 0.7Pb<P.sub.5 <
• 1.2Pb 1.8Pb<
• .vertline.P.sub.6 .vertline. <
• 2.3Pb, P.sub.6 <
• 0 0.5Pb<P.sub.7 <
• 0.9Pb 0.5Pb<P.sub.8 <
• 0.9Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, three negative meniscus lenses having their convex surfaces facing the object side and a positive lens having its convex surface facing the object side, said convergent lens group having, in succession from the object side, a positive lens, a negative meniscus lens comprising a cemented lens and having its convex surface facing the object side, a biconvex positive lens comprising a cemented lens, a biconcave negative lens, a positive meniscus lens having its convex surface facing the image side, and a positive lens, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.3.vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 1.2 .vertline.Pa.vertline., P.sub.1 <
• 0 0.02 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.9 .vertline.Pa.vertline., P.sub.2 <
• 0 0.3.vertline.Pa.vertline. <
• .vertline.P.sub.3 .vertline. <
• 0.9 .vertline.Pa.vertline., P.sub.3 <
• 0 0.2.vertline.Pa.vertline. <P.sub.4 <
• 0.8 .vertline.Pa.vertline. 0.3Pb<P.sub.5 <
• 1.3Pb -0.5Pb<P.sub.6 <
• 0.5Pb 0.7Pb<P.sub.7 <
• 1.4Pb 1.4Pb<
• .vertline.P.sub.8 .vertline. <
• 2.2Pb, P.sub.8 <
• 0 0.3Pb<P.sub.9 <
• 1.0Pb 0.3Pb<P.sub.10 <
• 0.8Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material havinng a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, three negative meniscus lenses having their convex surfaces facing the object side and a positive lens, said convergent lens group has, in succession from the object side, a biconvex positive lens, a negative meniscus lens comprising a cemented lens and having its convex surface facing the object side, a positive lens, a negative lens having its concave surface of sharper curvature facing the image side, and a positive lens having its convex surface of sharper curvature facing the image side, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.3 .vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 0.9 .vertline.Pa.vertline., P.sub.1 <
• 0 0.1 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.8 .vertline.Pa.vertline., P.sub.2 <
• 0 0.2 .vertline.Pa.vertline. <
• .vertline.P.sub.3 .vertline. <
• 0.8 .vertline.Pa.vertline., P.sub.3 <
• 0 0.3 .vertline.Pa.vertline. <P.sub.4 <
• 0.7 .vertline.Pa.vertline. 0.4Pb<P.sub.5 <
• 1.1Pb -0.4Pb<P.sub.6 <
• 0.4Pb 0.3Pb<P.sub.7 <
• 1.2Pb 0.7Pb<P.sub.8 <
• 1.9Pb 0.7Pb<P.sub.9 <
• 1.6Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, three negative meniscus lenses having their convex surfaces facing the object side, and a positive lens, said convergent lens group has, in succession from the object side, a positive lens, a negative meniscus lens comprising a cemented lens and having its convex surface facing the object side, a biconvex positive lens, a biconcave negative lens, a positive meniscus lens having its convex surface facing the image side, and a positive lens, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.5.vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 1.5 .vertline.Pa.vertline., P.sub.1 <
• 0 0.02 .vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.5 .vertline.Pa.vertline., P.sub.2 <
• 0 0.3.vertline.Pa.vertline. <
• .vertline.P.sub.3 .vertline. <
• 0.9 .vertline.Pa.vertline., P.sub.3 <
• 0 0.3.vertline.Pa.vertline. <P.sub.4 <
• 0.9 .vertline.Pa.vertline. 0.4Pb<P.sub.5 <
• 1.2Pb -0.6Pb<P.sub.6 <
• 0.6Pb 0.7Pb<P.sub.7 <
• 1.5Pb 1.1Pb<
• .vertline.P.sub.8 .vertline. <
• 2.4Pb, Pb.sub.8 <
• 0 0.3Pb<P.sub.9 <
• 1.1Pb 0.4Pb<P.sub.10 <
• 1.1Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.

A wide angle zoom lens having an angle of view of 90 degrees or greater at the wide angle end and a zoom ratio of 1.6 or greater and consisting of two lens groups which are, in succession from the object side, a divergent lens group and a convergent lens group, and in which magnification change is effected by relative movement of said two lens groups,

• said divergent lens group comprising at least two negative lenses and a positive lens disposed most adjacent to the image side, one of said negative lenses being formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less, said zoom lens being characterized in that said divergent lens group has, in succession from the object side, three negative meniscus lenses having their convex surfaces facing the object side and a positive lens, said convergent lens group has, in succession from the object side, a positive lens, a positive lens having a center thickness greater than that of the preceding positive lens, a negative lens, and two positive meniscus lenses having their convex surfaces facing the image side, and said zoom lens satisfies the following conditions:
• ______________________________________ 0.4.vertline.Pa.vertline. <
• .vertline.P.sub.1 .vertline. <
• 1.3.vertline.Pa .vertline., P.sub.1 <
• 0 0.1.vertline.Pa.vertline. <
• .vertline.P.sub.2 .vertline. <
• 0.5.vertline.Pa .vertline., P.sub.2 <
• 0 0.3.vertline.Pa.vertline. <
• .vertline.P.sub.3 .vertline. <
• 0.9.vertline.Pa .vertline., P.sub.3 <
• 0 0.45 .vertline.Pa.vertline. <P.sub.4 <
• 0.95 .vertline.Pa.vertline. 0.3Pb<P.sub.5 <
• 0.9Pb 0.4Pb<P.sub.6 <
• 1.3Pb 1.0Pb<
• .vertline.P.sub.7 .vertline. <
• 2.3Pb, P.sub.7 <
• 0 0.4Pb<P.sub.8 <
• 1.2Pb 0.4Pb<P.sub.9 <
• 1.2Pb ______________________________________
• where P.sub.1, P.sub.2, P.sub.3, . . . are the refractive powers of the successive lenses from the object side, Pa is the refractive power of said divergent lens group, and Pb is the refractive power of said convergent lens group.