Patent ID: 7777972

Claim:
An imaging optical lens assembly including, in order from an object side to an image side: a first lens group comprising a first lens element with positive refractive power, no lens element with refractive power being disposed between the first lens element and an imaged object, the first lens element being the only lens element with refractive power in the first lens group; and a second lens group comprising, in order from the object side to the image side: a second lens element with negative refractive power; a third lens element; and a fourth lens element; wherein focusing adjustment is performed by moving the first lens element along an optical axis, such that as a distance between the object and the imaging optical lens assembly changes from far to near, a distance between the first lens element and an image plane changes from near to far, and during focusing the other lens elements in the imaging optical lens assembly do not move relative to the imaging plane; and wherein the number of the lens elements with refractive power in the imaging optical lens assembly is N, and it satisfies the relation: 4≦N≦5.