IMAGING OPTICAL SYSTEM, AND IMAGING DEVICE USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an imaging optical system that has the small F number, maintains the entire length of the optical system short, has a wide angle of view, and suppresses an effect of various types of aberration, in particular coma aberration and spherical aberration.SOLUTION: An imaging optical system includes a first lens L1 having positive refractive power, a second lens L2 having negative refractive power, a third lens L3 having positive refractive power, and a fourth lens L4 having negative refractive power in order from an object side. The first lens L1 has a convex shape on both sides; the second lens L2 has an object-side surface r5 having a concave surface directed to an image side; the third lens L3 has at least an image-side surface r7 having a convex surface directed to the image side; and a diaphragm r1 is arranged closest to the object. The imaging optical system satisfies the following conditional expression (1): 0.9