IMAGE CAPTURING OPTICAL SYSTEM

An image capturing optical system includes ten lens elements which are, in order from an object side to an image side along an optical path: a first lens element having positive refractive power, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, an eighth lens element, a ninth lens element and a tenth lens element having negative refractive power. Each of the ten lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. The image-side surface of the second lens element is concave in a paraxial region thereof. At least one of the object-side surface and the image-side surface of at least one lens element of the image capturing optical system has at least one critical point in an off-axis region thereof.