Patent ID: 7471465

Claim:
An optical apparatus comprising at least one negative lens, a meniscus lens that is convex on an object side, an aperture stop, and a double-convex positive lens arranged from the object side to an image side, wherein at least one of the lenses positioned on the object side of the aperture stop and the positive lens include respective aspherical surfaces, and wherein, when va is an average Abbe number of all of the lenses excluding the meniscus lens, vb is an Abbe number of the meniscus lens, f is a focal length of the entire system, f 12 is a combined focal length of the negative lens unit and the meniscus lens, ts is a distance between the aperture stop and the positive lens along an axis, L is a distance between a vertex of a lens surface nearest to the object side and a vertex of a lens surface nearest to the image side, t 2 is a central thickness of the meniscus lens, θs is an incident angle of a chief ray that passes through the aperture stop at a maximum angle of view, the following Expression 1 is satisfied: 1.4 <va/vb; 0 <ts/L< 0.1 0.2 <t 2 /L< 0.5; −10 <f 12 /f<− 1.0; and 25°<θs<40° [Expression 1].