Image pickup optical system and image pickup apparatus using the same

Abstract

An image pickup optical system having four lenses includes in order from an object side, a first lens having a biconvex shape, and a positive refractive power, a second lens having a biconcave shape, and a negative refractive power, a third lens having a meniscus shape with a concave surface thereof directed toward the object side, and a positive refractive power, and a fourth lens having a biconcave shape, and a negative refractive power, and a diaphragm is disposed nearest to the object side, and the image pickup optical system satisfies the following conditional expressions −0.9<f4/f<0  (1) −0.04<(r8+r9)/(r8−r9)<1.3  (2) where, f4 denotes a focal length at a near-axis of the fourth lens, f denotes a focal length of the overall image pickup optical system, r8 denotes a radius of curvature of a surface on the object side of the fourth lens, and r9 denotes a radius of curvature of a surface on an image side of the fourth lens.

Dependencies are inferred from the claim text.