Patent ID: 8878975

Claim:
An image optical lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; second lens element with negative refractive power; a third lens element with positive refractive power made of plastic material and having a convex image-side surface, wherein an object-side surface and the image-side surface of the third lens element are aspheric; and a fourth lens element with negative refractive power made of plastic material, and having a concave object-side surface and a concave image-side surface, wherein the object-side surface and the image-side surface of the fourth lens element are aspheric, and the image-side surface of the fourth lens element changes from concave at the paraxial region to convex at the peripheral region; wherein a maximum chief ray angle of the mage optical lens system is CRA(Max), a curvature radius of the object-side surface of the third lens element is R5, a curvature radius of the image-side surface of the third lens element is R6, a central thickness of the first lens element is CT1, and a central thickness of the third lens element is CT3, the following relationships are satisfied: 33.5 degrees<CRA(Max)<45.0 degrees; 0.7<( R 5 +R 6)/( R 5 −R 6)<3.5; and 1.2<CT3/CT1<3.0.