Image system lens assembly, image capturing unit and electronic device

1. An image system lens assembly comprising seven lens elements, the seven 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 and a seventh lens element;

wherein at least one surface among object-side surfaces and image-side surfaces of the seven lens elements has at least one critical point in an off-axis region thereof;

wherein a number of lens element having an Abbe number less than 38 among the seven lens elements is NVd38, a curvature radius of an object-side surface of the fifth lens element is R9, a curvature radius of an image-side surface of the fifth lens element is R10, a curvature radius of an image-side surface of the seventh lens element is R14, a focal length of the image system lens assembly is f, and the following conditions are satisfied:

5≤ NVd 38;

0< R 14/ f≤ 0.48; and

0≤| f/R 9|+| f/R 10|<5.0.

2. The image system lens assembly of claim 1 , wherein at least one of the seven lens elements has an Abbe number less than 20.

3. The image system lens assembly of claim 1 , wherein each of at least three adjacent lens elements among the seven lens elements has an Abbe number less than 38.

4. The image system lens assembly of claim 1 , wherein a central thickness of the sixth lens element is CT6, a central thickness of the seventh lens element is CT7, and the following condition is satisfied:

1.02≤ CT 6/ CT 7<2.10.

5. The image system lens assembly of claim 1 , wherein the seventh lens element has an object-side surface being convex in a paraxial region thereof, the focal length of the image system lens assembly is f, a focal length of the first lens element is f1, a focal length of the seventh lens element is f7, and the following conditions are satisfied:

0.69≤ f/f 1<3.0; and

−1.70≤ f/f 7<3.0.

6. The image system lens assembly of claim 1 , further comprising an aperture stop disposed between an imaged object and the first lens element, wherein a curvature radius of an object-side surface of the third lens element is R5, the focal length of the image system lens assembly is f, and the following condition is satisfied:

−3.0< R 5/ f< 3.0.

7. An image system lens assembly comprising seven lens elements, the seven 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 and a seventh lens element;

wherein at least one surface among object-side surfaces and image-side surfaces of the fifth lens element, the sixth lens element and the seventh lens element has at least one critical point in an off-axis region thereof;

wherein at least one of the seven lens elements has an Abbe number less than 20, a number of lens element having an Abbe number less than 38 among the seven lens elements is NVd38, a focal length of the image system lens assembly is f, a focal length of the first lens element is f1, a displacement in parallel with an optical axis from an axial vertex of an image-side surface of the fourth lens element to a maximum effective radius position of the image-side surface of the fourth lens element is Sag42, a central thickness of the fourth lens element is CT4, and the following conditions are satisfied:

5≤ NVd 38;

−0.5< f/f 1≤1.10; and

−1.5< Sag 42/ CT 4<3.0.

8. The image system lens assembly of claim 7 , wherein a number of lens element having an Abbe number less than 32 among the seven lens elements is NVd32, and the following condition is satisfied:

5≤ NVd 32.

9. The image system lens assembly of claim 7 , wherein a sum of Abbe numbers of the seven lens elements of the image system lens assembly is ΣVd, and the following condition is satisfied:

70.0<Σ Vd< 245.0.

10. The image system lens assembly of claim 7 , wherein a curvature radius of an object-side surface of the third lens element is R5, the focal length of the image system lens assembly is f, a focal length of the sixth lens element is f6, and the following conditions are satisfied:

−3.0< R 5/ f< 3.0; and

0.40< f/f 6<2.5.

11. The image system lens assembly of claim 7 , wherein an f-number of the image system lens assembly is Fno, an axial distance between an object-side surface of the first lens element and an image surface is TL, an entrance pupil diameter of the image system lens assembly is EPD, and the following conditions are satisfied:

0.8< Fno< 2.4;

2.0 mm< TL< 8.0 mm; and

0.8< TL/EPD< 2.8.

12. The image system lens assembly of claim 7 , wherein the first lens element has positive refractive power, the first lens element has an object-side surface being convex in a paraxial region thereof, a curvature radius of the object-side surface of the first lens element is R1, the focal length of the image system lens assembly is f, and the following condition is satisfied:

0.44≤ R 1/ f< 1.5.

13. The image system lens assembly of claim 7 , wherein the second lens element has negative refractive power, and the second lens element has an object-side surface being convex in a paraxial region thereof and an image-side surface being concave in a paraxial region thereof.

14. The image system lens assembly of claim 7 , wherein the sixth lens element has an object-side surface being convex in a paraxial region thereof, and the object-side surface of the sixth lens element comprises a critical point in an off-axis region thereof.

15. The image system lens assembly of claim 7 , wherein each of at least two of the seven lens elements has at least one inflection point, the seventh lens element has negative refractive power, and the seventh lens element has an image-side surface being concave in a paraxial region thereof.

16. An image system lens assembly comprising seven lens elements, the seven 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 and a seventh lens element;

wherein the seventh lens element has an image-side surface being concave in a paraxial region thereof, at least one surface among object-side surfaces and image-side surfaces of the seven lens elements has at least one critical point in an off-axis region thereof;

wherein a number of lens element having an Abbe number less than 38 among the seven lens elements is NVd38, a focal length of the image system lens assembly is f, a focal length of the sixth lens element is f6, a composite focal length of the first lens element and the second lens element is f12, a curvature radius of the image-side surface of the seventh lens element is R14, and the following conditions are satisfied:

5≤ NVd 38;

−1.07≤ f/f 6<3.0;

0.60< f/f 12<2.0; and

0< R 14/ f< 1.6.

17. The image system lens assembly of claim 16 , wherein at least one of the seven lens elements has an Abbe number less than 20.

18. The image system lens assembly of claim 16 , wherein the focal length of the image system lens assembly is f, a focal length of the fifth lens element is f5, and the following condition is satisfied:

−1.5< f/f 5≤−0.61.

19. The image system lens assembly of claim 16 , wherein the seventh lens element has negative refractive power, and the seventh lens element has an object-side surface being convex in a paraxial region thereof.

20. The image system lens assembly of claim 16 , further comprising an aperture stop disposed between an imaged object and the first lens element, wherein a central thickness of the sixth lens element is CT6, a central thickness of the seventh lens element is CT7, and the following condition is satisfied:

0< CT 6/ CT 7<2.10.