Optical imaging system, imaging apparatus and electronic device

1. An optical imaging system, comprising five lens elements, the five 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 and a fifth lens element; each of the five lens elements comprising 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 second lens element has negative refractive power and the image-side surface of the second lens element is concave in a paraxial region thereof, the object-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 and the image-side surface of the fifth lens element is concave in a paraxial region thereof, at least three lens elements among the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element have their Abbe numbers less than 40.0;

wherein a focal length of the optical imaging system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element is TD, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, and the following conditions are satisfied:

1.90< f/TD;

0.19< T 12/ T 23<9.7; and

| f 2|/ f 1<1.0.

2. The optical imaging system of claim 1 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, the axial distance between the first lens element and the second lens element is T12, the axial distance between the second lens element and the third lens element is T23, and the following condition is satisfied:

0.19< T 12/ T 23<3.3.

3. The optical imaging system of claim 1 , wherein the image-side surface of the fourth lens element is convex in a paraxial region thereof, a vertical distance between a maximum effective diameter position on the object-side surface of the first lens element and an optical axis is Y11, a vertical distance between a maximum effective diameter position on the image-side surface of the fifth lens element and the optical axis is Y52, and the following condition is satisfied:

0.80< Y 11/ Y 52<1.50.

4. The optical imaging system of claim 1 , further comprising at least one reflective component disposed at the object side of the first lens element.

5. An optical imaging system, comprising five lens elements, the five 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 and a fifth lens element; each of the five lens elements comprising 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 image-side surface of the first lens element is convex in a paraxial region thereof, the third lens element has positive refractive power, the object-side surface of the third lens element is convex in a paraxial region thereof, the object-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 and the image-side surface of the fifth lens element is concave in a paraxial region thereof, at least three lens elements among the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element have their Abbe numbers less than 40.0;

wherein a focal length of the optical imaging system is f, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element is TD, a curvature radius of the object-side surface of the third lens element is R5, an axial distance between the second lens element and the third lens element is T23, a central thickness of the third lens element is CT3, and the following conditions are satisfied:

1.90< f/TD;

1.5< f/R 5<5.5; and

0.50< T 23/ CT 3<1.24.

6. The optical imaging system of claim 5 , wherein the focal length of the optical imaging system is f, a curvature radius of the image-side surface of the fifth lens element is R10, and the following condition is satisfied:

4.0< f/R 10<10.

7. The optical imaging system of claim 5 , wherein a vertical distance between a maximum effective diameter position on the object-side surface of the first lens element and an optical axis is Y11, a vertical distance between a maximum effective diameter position on the image-side surface of the fifth lens element and the optical axis is Y52, and the following condition is satisfied:

0.90< Y 11/ Y 52<1.30.

8. The optical imaging system of claim 5 , wherein 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, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and the following condition is satisfied:

| f 2|/ f 1<1.0.

9. The optical imaging system of claim 5 , wherein the image-side surface of the fourth lens element is convex in a paraxial region thereof, the focal length of the optical imaging system is f, a focal length of the first lens element is f1, a focal length of the second lens element is f2, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5 and the following condition is satisfied:

8.0<| f/f 1|+| f/f 2|+| f/f 3|+| f/f 4|+| f/f 5|<20.0.

10. The optical imaging system of claim 5 , further comprising at least one reflective component disposed at the object side of the first lens element.

11. The optical imaging system of claim 10 , wherein the at least one reflective component is a prism.

12. An optical imaging system, comprising five lens elements, the five 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 and a fifth lens element; each of the five lens elements comprising an object-side surface facing toward the object side and an image-side surface facing toward the image side;

wherein the second lens element has negative refractive power, the object-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 and the image-side surface of the fifth lens element is concave in a paraxial region thereof, at least three lens elements among the first lens element, the second lens element, the third lens element, the fourth lens element and the fifth lens element have their Abbe numbers less than 40.0;

wherein a focal length of the optical imaging system is f, an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element is TD, a focal length of the first lens element is f1, a focal length of the second lens element is f2, and the following conditions are satisfied:

1.90< f/TD ; and

| f 2|/ f 1<1.0.

13. The optical imaging system of claim 12 , wherein the image-side surface of the first lens element is convex in a paraxial region thereof, an axial distance between the second lens element and the third lens element is T23, a central thickness of the third lens element is CT3, and the following condition is satisfied:

0.50< T 23/ CT 3<1.24.

14. The optical imaging system of claim 12 , wherein the focal length of the optical imaging system is f, a curvature radius of the image-side surface of the fifth lens element is R10, and the following condition is satisfied:

4.0< f/R 10<10.

15. The optical imaging system of claim 12 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, an axial distance between the first lens element and the second lens element is T12, an axial distance between the second lens element and the third lens element is T23, and the following condition is satisfied:

0.05< T 12/ T 23<9.7.

16. The optical imaging system of claim 12 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, the object-side surface of the third lens element is convex in a paraxial region thereof, the focal length of the optical imaging system is f, a curvature radius of the object-side surface of the third lens element is R5, and the following condition is satisfied:

0.22< f/R 5<8.0.

17. The optical imaging system of claim 12 , wherein the object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the fourth lens element is convex in a paraxial region thereof, the focal length of the optical imaging system is f, the focal length of the first lens element is f1, the focal length of the second lens element is f2, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5 and the following condition is satisfied:

8.0<| f/f 1|+| f/f 2|+| f/f 3|+| f/f 4|+| f/f 5|<20.0.

18. The optical imaging system of claim 12 , wherein the object-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the fourth lens element is convex in a paraxial region thereof, a vertical distance between a maximum effective diameter position on the object-side surface of the first lens element and an optical axis is Y11, a vertical distance between a maximum effective diameter position on the image-side surface of the fifth lens element and the optical axis is Y52, and the following condition is satisfied:

0.80< Y 11/ Y 52<1.50.

19. The optical imaging system of claim 12 , further comprising at least one reflective component disposed at the object side of the first lens element, and the at least one reflective component is a prism.