Lens apparatus

Abstract

From an object, a first lens that is a meniscus lens having a convex surface that faces an object, a second lens that faces a concave surface of the first lens, a third lens having a concave surface that faces the second lens, and a fourth lens that is a positive lens having a convex back surface, (1) ν3<ν4, (2) 0.5<Ymax/f<0.8, and (3) Σd<1.5f are satisfied, where ν3 is an Abbe number of the third lens, ν4 is an Abbe number of the fourth lens, Ymax is a maximum height of an image, f is a composite focal length, Σd is a distance between a first surface of the first lens and a second surface of the fourth lens, the first surface facing the object and the second surface facing an imaging plane, any one surface of the first lens and the fourth lens having a non-spherical surface.

Dependencies are inferred from the claim text.