Patent ID: 11971609
Assignee: LARGAN PRECISION CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 14:
15. A photographing optical system comprising eight lens elements, the eight lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element and an eighth lens element, and each of the eight lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein the first lens element has positive refractive power, the object-side surface of the second lens element is convex in a paraxial region thereof, the fifth lens element has positive refractive power, the seventh lens element has positive refractive power, the object-side surface of the seventh lens element is convex in a paraxial region thereof, the image-side surface of the seventh lens element is concave in a paraxial region thereof, and at least one lens surface of at least one lens element of the photographing optical system has at least one critical point in an off-axis region thereof;
wherein a focal length of the photographing optical system is f, a focal length of the first lens element is f1, a focal length of the fifth lens element is f5, a curvature radius of the object-side surface of the second lens element is R3, a curvature radius of the object-side surface of the fifth lens element is R9, a curvature radius of the image-side surface of the fifth lens element is R10, an Abbe number of the second lens element is V2, an Abbe number of the sixth lens element is V6, a central thickness of the third lens element is CT3, a central thickness of the fifth lens element is CT5, and the following conditions are satisfied:

0<f5/f1<9.5;

0<R3/f<2.0;

−1.5<(R9+R10)/(R9-R10)<1.5;

10.0<V2<50.0;

15.0<V6<50.0; and

1.0<CT5/CT3.