Photographing system lens assembly, image capturing unit and electronic device
A photographing system lens assembly includes, in order from an object side to an image side: a first lens element, a second lens element, a third lens element and a fourth lens element. Each of the four lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. At least one surface of at least one lens element in the photographing system lens assembly has at least one inflection point. The first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, and the image-side surface of the first lens element is convex in a paraxial region thereof. The object-side surface of the second lens element is concave in a paraxial region thereof. The image-side surface of the third lens element is concave in a paraxial region thereof.
1 . A photographing system lens assembly comprising four lens elements, the four lens elements being, in order from an object side to an image side along an optical path, a first lens element, a second lens element, a third lens element and a fourth lens element, and each of the four lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein a total number of lens elements in the photographing system lens assembly is four, an air gap is in a paraxial region between each of all adjacent lens elements of the photographing system lens assembly, the first lens element has positive refractive power, the object-side surface of the first lens element is convex in a paraxial region thereof, the image-side surface of the first lens element is convex in a paraxial region thereof, the object-side surface of the second lens element is concave in a paraxial region thereof, and the third lens element has negative refractive power;
wherein an axial distance between the image-side surface of the fourth lens element and an image surface is BL, an axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, a focal length of the first lens element is f1, a curvature radius of the image-side surface of the first lens element is R2, 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, 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 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 i-th lens element is Ni, a minimum value of Vi/Ni is (Vi/Ni)min, and the following conditions are satisfied:
2.20< BL/TD< 10.00;
−20.00< R 2/ f 1<−0.01;
1.25<| R 5/ R 6|<100.00;
7.00<( Vi/Ni )min<20.00, wherein i= 1, 2, 3 or 4; and
1.420< N 4<1.710.
2 . The photographing system lens assembly of claim 1 , wherein a chief ray angle of a maximum field of view on the image surface of the photographing system lens assembly is CRA_D, half of the maximum field of view of the photographing system lens assembly is HFOV, and the following conditions are satisfied:
5.0 degrees< CRA _ D< 35.0 degrees; and
8.0 degrees<HFOV<20.0 degrees.
3 . The photographing system lens assembly of claim 1 , wherein a minimum value among Abbe numbers of all lens elements of the photographing system lens assembly is Vmin, and the following condition is satisfied:
6.0< V min<29.0.
4 . The photographing system lens assembly of claim 1 , wherein a maximum effective radius of the object-side surface of the first lens element is Y1R1, a maximum effective radius of the image-side surface of the fourth lens element is Y4R2, and the following condition is satisfied:
1.10< Y 1 R 1/ Y 4 R 2<1.60.
5 . The photographing system lens assembly of claim 1 , wherein a displacement in parallel with an optical axis from an axial vertex of the image-side surface of the first lens element to a maximum effective radius position of the image-side surface of the first lens element is SAG1R2, a central thickness of the fourth lens element is CT4, and the following condition is satisfied:
−2.50< SAG 1 R 2/ CT 4<−0.10.
6 . The photographing system lens assembly of claim 1 , wherein the axial distance between the object-side surface of the first lens element and the image-side surface of the fourth lens element is TD, an axial distance between the first lens element and the second lens element is T12, and the following condition is satisfied:
2.00< TD/T 12<80.00.
7 . The photographing system lens assembly of claim 1 , further comprising at least one reflective element disposed between the fourth lens element and the image surface.
8 . The photographing system lens assembly of claim 7 , wherein the at least one reflective element comprises a prism, and the optical path is deflected at least two times by the prism.