Patent ID: 8218247

Claim:
A zoom lens extending along an optical axis and formed by arranging a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power in order from an object side to an image side, wherein at a time of varying power from a wide-angle end to a telephoto end, said first lens group is moved and said second lens group is moved to the object side integrally with a diaphragm such that an air interval between said first lens group and said second lens group is decreased and such that an air interval between said second lens group and said third lens group is increased, said first lens group is formed by arranging a first lens as a negative lens having both surfaces formed as aspheric surfaces and having a concave surface facing the image side and a second lens as a positive meniscus lens having a second lens surface on the object side formed as an aspheric surface and having a convex surface facing the object side in order from the object side to the image side, the concave surface of the first lens has a central part extending radially outwardly from and axially along the optical axis and a peripheral part integrally connected to and surrounding the central part of the concave surface and extending radially outwardly therefrom and axially along the optical axis, the second lens surface of the second lens has a central part extending radially outwardly from and axially along the optical axis and a peripheral part integrally connected to and surrounding the central part of the second lens surface and extending radially outwardly therefrom and axially along the optical axis, a radius of curvature of the central part of the concave surface on the image side of the first lens is less than a radius of curvature of the central part of the second lens surface on the object side of the second lens and a radius of curvature of the peripheral part of the concave surface on an image side of the first lens is less than a radius of curvature of the peripheral part of the second lens surface on the object side of the second lens with respective center points of the radii of curvature being located on the optical axis of the zoom lens.