Patent ID: 8411369

Claim:
An imaging lens comprising, in order from an object side: a first lens group having positive refractive power; a second lens group having positive refractive power; and a third lens group having negative refractive power, said first lens group including a negative meniscus lens with a concave surface directed to an image side disposed closest to the object, an aperture stop being disposed between said first lens group and said second lens group, said first lens group and said second lens group moving to the object side with changing a distance between said first lens group and said second lens group upon focusing on a near-distance object point from an infinite-distance object point, at least one optical surface of said first lens group being provided with an antireflection coating, said antireflection coating including at least one layer formed by use of a wet process, and when nd is a refractive index of the layer formed by use of the wet process, nd being equal to or smaller than 1.30.