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

Claim 0:
1. 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 fifth 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 focal length of the seventh lens element is f7, a focal length of the eighth lens element is f8, a composite focal length of the first lens element and the second lens element is f12, an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, an Abbe number of the fifth lens element is V5, an Abbe number of the sixth lens element is V6, an Abbe number of the seventh lens element is V7, an Abbe number of the eighth lens element is V8, an Abbe number of the i-th lens element is Vi, a refractive index of the first lens element is N1, a refractive index of the second lens element is N2, a refractive index of the third lens element is N3, a refractive index of the fourth lens element is N4, a refractive index of the fifth lens element is N5, a refractive index of the sixth lens element is N6, a refractive index of the seventh lens element is N7, a refractive index of the eighth lens element is N8, a refractive index of the i-th lens element is Ni, a minimum value of Vi/Ni is (Vi/Ni)min, an f-number of the photographing optical system is Fno, half of a maximum field of view of the photographing optical system is HFOV, a maximum effective radius of the object-side surface of the first lens element is Y11, a maximum effective radius of the image-side surface of the eighth lens element is Y82, and the following conditions are satisfied:

0<f5/f1<9.5;

−7.5<f8/f7<−0.55;

0.35<f/f12<0.75;

6.0<(Vi/Ni)min<12.0, wherein i=1, 2, 3, 4, 5, 6,7 or 8;

1.0<Fno<2.2;

30.0[deg.]<HFOV<50.0[deg.]; and

1.8<Y82/Y11<3.0.