IMAGE PICKUP OPTICAL SYSTEM, IMAGE PICKUP DEVICE, AND DIGITAL APPARATUS

摘要

This image pickup optical system has: a first positive lens having a convex surface on the object side; a second negative lens having a concave surface on the image side; a third lens having regions where lens cross sections are further on the object side than the intersections with the optical axis, said regions being on both the surfaces; a fourth positive lens, which has an aspheric shape with an inflexion point at least on one surface, and has a convex surface on the image side; and a fifth negative lens having a concave surface on the image side. When focal point distances of the whole system and the first and the fourth lens are represented by f, f1 and f4, respectively, and the paraxial radii of the surfaces are represented by R1_L3 and R2_L3, respectively, the image pickup optical system satisfies the formulas of 0.5<|f1/f|<0.67 and 0.3<|f4/f|<0.63, and the third lens satisfies the formulas of -0.4