Imaging lens system, image capturing unit and electronic device
An imaging lens system includes eight lens elements which are, 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. Each of the eight 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 lens element of the imaging lens system has at least one lens surface having at least one inflection point. The imaging lens system has a total of eight lens elements.
1. An imaging lens system comprising a total of 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 fifth lens element has positive refractive power, the image-side surface of the fourth lens element is concave in a paraxial region thereof, the object-side surface of the fifth lens element is convex in a paraxial region thereof, the object-side surface of the sixth lens element is concave in a paraxial region thereof, the image-side surface of the eighth lens element is concave in a paraxial region thereof, and at least one of the eight lens elements has at least one lens surface having at least one inflection point;
wherein a central thickness of the eighth lens element is larger than a central thickness of the second lens element;
wherein a minimum value among Abbe numbers of all lens elements of the imaging lens system is Vmin, half of a maximum field of view of the imaging lens system is HFOV, a focal length of the imaging lens system is f, an entrance pupil diameter of the imaging lens system is EPD, and the following conditions are satisfied:
10<Vmin<20.0;
5.0 degrees<HFOV<25.0 degrees; and
0.20< f ×tan(HFOV)/ EPD< 0.73.
2. The imaging lens system of claim 1 , wherein 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 each of at least three lens elements of the imaging lens system has at least one lens surface having at least one inflection point.
3. The imaging lens system of claim 1 , wherein at least four lens elements of the imaging lens system are made of plastic material;
wherein a curvature radius of the image-side surface of the fourth lens element is R 8 , the focal length of the imaging lens system is f, and the following condition is satisfied:
−1.50< R 8/ f< 1.50.
4. The imaging lens system of claim 1 , wherein a curvature radius of the object-side surface of the seventh lens element is R 13 , a curvature radius of the image-side surface of the seventh lens element is R 14 , and the following condition is satisfied:
−2.0<( R 13 − R 14 )/( R 13 + R 14 )<3.0.
5. The imaging lens system of claim 1 , wherein a central thickness of the sixth lens element is larger than a central thickness of the seventh lens element.
6. The imaging lens system of claim 1 , wherein each of at least four lens elements of the imaging lens system has an Abbe number smaller than 30.0.
7. The imaging lens system of claim 1 , wherein a maximum effective radius of the object-side surface of the first lens element is Y 11 , a maximum effective radius of the image-side surface of the eighth lens element is Y 82 , a maximum image height of the imaging lens system is ImgH, the focal length of the imaging lens system is f, and the following condition is satisfied:
0<(| Y 11 − Y 82 |+| Y 82 -ImgH|)/ f< 0.15.
8. The imaging lens system of claim 1 , wherein a maximum effective radius of the object-side surface of the first lens element is Y 11 , a maximum effective radius of the image-side surface of the eighth lens element is Y 82 , an axial distance between the image-side surface of the eighth lens element and an image surface is BL, the focal length of the imaging lens system is f, and the following condition is satisfied:
0<(| Y 11 − Y 82 |+BL)/ f< 0.20.
9. The imaging lens system of claim 1 , wherein an absolute value of a curvature radius of the image-side surface of the first lens element is larger than an absolute value of a curvature radius of the object-side surface of the eighth lens element.
10. The imaging lens system of claim 1 , wherein an axial distance between the fourth lens element and the fifth lens element is larger than an axial distance between the seventh lens element and the eighth lens element.
11. The imaging lens system of claim 1 , wherein an axial distance between the sixth lens element and the seventh lens element is larger than an axial distance between the third lens element and the fourth lens element.
12. An image capturing unit comprising:
the imaging lens system of claim 1 ; and
an image sensor disposed on an image surface of the imaging lens system.
13. An electronic device comprising at least two image capturing units, wherein the at least two image capturing units face a same side and comprise:
a first image capturing unit comprising the imaging lens system of claim 1 and a first image sensor, wherein the first image sensor is disposed on an image surface of the imaging lens system; and
a second image capturing unit comprising an optical lens assembly and a second image sensor, wherein the second image sensor is disposed on an image surface of the optical lens assembly.
14. An imaging lens system comprising a total of 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 image-side surface of the second lens element is convex in a paraxial region thereof, the object-side surface of the third lens element is concave in a paraxial region thereof, the image-side surface of the fourth lens element is concave in a paraxial region thereof, the object-side surface of the sixth lens element is concave in a paraxial region thereof, the object-side surface of the eighth lens element is convex in a paraxial region thereof, and at least one lens element of the imaging lens system has at least one lens surface having at least one inflection point;
wherein a central thickness of the sixth lens element is larger than a central thickness of the second lens element;
wherein a maximum effective radius of the object-side surface of the first lens element is Y 11 , a maximum effective radius of the image-side surface of the eighth lens element is Y 82 , an axial distance between the image-side surface of the eighth lens element and an image surface is BL, a focal length of the imaging lens system is f, and the following condition is satisfied:
0<(| Y 11 − Y 82 |+ BL )/ f< 0.20.
15. The imaging lens system of claim 14 , wherein half of a maximum field of view of the imaging lens system is HFOV, and the following condition is satisfied:
5.0 degrees<HFOV<25.0 degrees.
16. The imaging lens system of claim 14 , wherein a minimum value among Abbe numbers of all lens elements of the imaging lens system is Vmin, and the following condition is satisfied:
8.0<Vmin<22.5.
17. The imaging lens system of claim 14 , wherein the object-side surface of the first lens element is convex in a paraxial region thereof, and each of at least two lens elements of the imaging lens system has at least one lens surface having at least one inflection point.
18. The imaging lens system of claim 14 , wherein at least four lens elements of the imaging lens system are made of plastic material; and
wherein the axial distance between the image-side surface of the eighth lens element and the image surface is BL, an axial distance between the object-side surface of the first lens element and the image-side surface of the eighth lens element is TD, and the following condition is satisfied:
0< BL/TD< 0.18.
19. The imaging lens system of claim 14 , wherein the focal length of the imaging lens system is f, half of a maximum field of view of the imaging lens system is HFOV, an entrance pupil diameter of the imaging lens system is EPD, and the following condition is satisfied:
0.20< f ×tan(HFOV)/ EPD< 1.0.
20. The imaging lens system of claim 14 , wherein the focal length of the imaging lens system is f, a focal length of the fifth lens element is f 5 , and the following condition is satisfied:
−0.25< f/f 5<1.50.
21. The imaging lens system of claim 14 , wherein a central thickness of the eighth lens element is larger than an axial distance between the seventh lens element and the eighth lens element;
wherein a curvature radius of the object-side surface of the seventh lens element is R 13 , a curvature radius of the image-side surface of the seventh lens element is R 14 , and the following condition is satisfied:
−2.0<( R 13 − R 14 )/( R 13 + R 14 )<3.0.
22. The imaging lens system of claim 14 , wherein each of at least four lens elements of the imaging lens system has an Abbe number smaller than 35.0.
23. The imaging lens system of claim 14 , wherein an Abbe number of the first lens element is V 1 , an Abbe number of the second lens element is V 2 , an Abbe number of the third lens element is V 3 , an Abbe number of the fourth lens element is V 4 , an Abbe number of the fifth lens element is V 5 , an Abbe number of the sixth lens element is V 6 , an Abbe number of the seventh lens element is V 7 , an Abbe number of the eighth lens element is V 8 , an Abbe number of the i-th lens element is Vi, a maximum image height of the imaging lens system is ImgH, and the following conditions are satisfied:
150.0<Σ Vi< 320.0, wherein i= 1, 2, 3, 4, 5, 6, 7, 8; and
1.50 mm<ImgH<4.50 mm.
24. The imaging lens system of claim 14 , wherein the maximum effective radius of the object-side surface of the first lens element is Y 11 , the maximum effective radius of the image-side surface of the eighth lens element is Y 82 , a maximum image height of the imaging lens system is ImgH, the focal length of the imaging lens system is f, and the following condition is satisfied:
0<(| Y 11 − Y 82 |+| Y 82 −ImgH|)/ f< 0.15.