Image capturing optical system, imaging apparatus and electronic device

1. An image capturing optical system 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 each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;

wherein the first lens element has positive refractive power, the second lens element has negative refractive power, the image-side surface of the sixth lens element is concave in a paraxial region thereof, and the object-side surface of the seventh lens element is concave in a paraxial region thereof;

wherein each of at least three of the seven lens elements has at least one aspheric surface; at least one surface of the seven lens elements comprises at least one inflection point; each of at least two of the seven lens elements has an Abbe number smaller than 25.0;

wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, an entrance pupil diameter of the image capturing optical system is EPD, an axial distance between the sixth lens element and the seventh lens element is T67, a central thickness of the sixth lens element is CT6, and the following conditions are satisfied:

1.15 <TL /EPD<2.0; and

0.70< T 67/CT6<5.50.

2. The image capturing optical system of claim 1 , wherein 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 concave in a paraxial region thereof; the axial distance between the object-side surface of the first lens element and the image surface is TL, a maximum image height of the image capturing optical system is ImgH, and the following condition is satisfied:

TL /Img H≤ 1.51.

3. The image capturing optical system of claim 1 , wherein the axial distance between the object-side surface of the first lens element and the image surface is TL, a focal length of the image capturing optical system is f, the entrance pupil diameter of the image capturing optical system is EPD, a maximum image height of the image capturing optical system is ImgH, and the following condition is satisfied:

( TL×f )/(EPD×Img H )<2.35.

4. The image capturing optical system of claim 1 , wherein each of at least three of the seven lens elements has an Abbe number smaller than 25.0.

5. The image capturing optical system of claim 1 , wherein a maximum of chief ray angles of the image capturing optical system is CRAmax, and the following condition is satisfied:

35.0 degrees<CRAmax<50.0 degrees.

6. The image capturing optical system of claim 1 , wherein a focal length of the image capturing optical system is f, a focal length of the second lens element is f2, the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the image capturing optical system is EPD, a maximum image height of the image capturing optical system is ImgH, and the following conditions are satisfied:

0.40<| f/f 2|<1.20; and

( TL×f )/(EPD×Img H )<2.50.

7. An image capturing optical system 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 each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;

wherein the first lens element has positive refractive power, the second lens element has negative refractive power, the image-side surface of the third lens element is convex in a paraxial region thereof, the image-side surface of the sixth lens element is concave in a paraxial region thereof, and the object-side surface of the seventh lens element is concave in a paraxial region thereof;

wherein each of at least three of the seven lens elements has at least one aspheric surface; at least one surface of the seven lens elements comprises at least one inflection point; each of at least two of the seven lens elements has an Abbe number smaller than 25.0;

wherein an axial distance between the object-side surface of the first lens element and an Image surface is TL, an entrance pupil diameter of the Image capturing optical system is EPD, an axial distance between the sixth lens element and the seventh lens element is T67, a central thickness of the sixth lens element is CT6, and the following conditions are satisfied:

1.05 <TL /EPD<2.38; and

0.70< T 67/CT8<5.50.

8. The Image capturing optical system of claim 7 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof; the seventh lens element has negative refractive power.

9. The image capturing optical system of claim 7 , wherein each of at least three of the seven lens elements has an Abbe number smaller than 25.0.

10. The image capturing optical system of claim 7 , wherein a vertical distance between a non-axial critical point on the image-side surface of the seventh lens element and an optical axis is Yc72, a focal length of the image capturing optical system is f, the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the image capturing optical system is EPD, and the following conditions are satisfied:

0.10< Yc 72/ f< 0.85; and

1.10 <TL /EPD<2.20.

11. The image capturing optical system of claim 7 , wherein the axial distance between the object-side surface of the first lens element and the Image surface is TL, a maximum Image height of the Image capturing optical system is ImgH, and the following condition is satisfied:

TL /Img H ≤1.51.

12. An imaging apparatus, comprising:

the image capturing optical system of claim 7 ;

a driving apparatus connected to the image capturing optical system; and

an image sensor disposed on an Image surface of the image capturing optical system.

13. An electronic device, comprising:

the imaging apparatus of claim 12 .

14. An image capturing optical system 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 each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;

wherein the first lens element has positive refractive power, the second lens element has negative refractive power, the image-side surface of the sixth lens element is concave in a paraxial region thereof, and the object-side surface of the seventh lens element is concave in a paraxial region thereof;

wherein each of at least three of the seven lens elements has at least one aspheric surface; at least one surface of the seven lens elements comprises at least one inflection point; each of at least two of the seven lens elements has an Abbe number smaller than 25.0;

wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, an entrance pupil diameter of the image capturing optical system is EPD, an axial distance between the sixth lens element and the seventh lens element is T67, a central thickness of the sixth lens element is CT6, a half of a maximum field of view of the image capturing optical system is HFOV, and the following conditions are satisfied:

1.05 <TL /EPD<2.38;

0.70< T 67/CT6<5.50;

0.84≤tan(HFOV)<1.20; and

TL< 7.5 mm.

15. The image capturing optical system of claim 14 , wherein the object-side surface of the fourth lens element is concave in a paraxial region thereof.

16. The Image capturing optical system of claim 14 , wherein the image-side surface of the seventh lens element is concave in a paraxial region thereof and comprises at least one convex surface in an off-axis region thereof.

17. The Image capturing optical system of claim 14 , wherein the axial distance between the object-side surface of the first lens element and the Image surface is TL, a focal length of the image capturing optical system is f, the entrance pupil diameter of the Image capturing optical system is EPD, a maximum Image height of the image capturing optical system is ImgH, and the following condition is satisfied:

( TL×f )/(EPD×Img H )<2.35.

18. The image capturing optical system of claim 14 , further comprising:

an aperture stop located on an object side of the second lens element, wherein the axial distance between the object-side surface of the first lens element and the Image surface is TL, a maximum Image height of the image capturing optical system is ImgH, an axial distance between the aperture stop and the image-side surface of the seventh lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element is TD, and the following conditions are satisfied:

TL /Img H <2.0; and

0.80< SD/TD< 0.98.

19. The image capturing optical system of claim 14 , wherein the axial distance between the sixth lens element and the seventh lens element is a maximum among axial distances between adjacent lens elements of the seven lens elements.

20. An Image capturing optical system 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 each of the seven lens elements has an object-side surface facing towards the object side and an image-side surface facing towards the image side;

wherein the first lens element has positive refractive power, the second lens element has negative refractive power, the image-side surface of the second lens element is concave in a paraxial region thereof, the image-side surface of the sixth lens element is concave in a paraxial region thereof, and the object-side surface of the seventh lens element is concave in a paraxial region thereof;

wherein each of at least three of the seven lens elements has at least one aspheric surface; at least one surface of the seven lens elements comprises at least one inflection point; each of at least two of the seven lens elements has an Abbe number smaller than 25.0;

wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, an entrance pupil diameter of the image capturing optical system is EPD, a half of a maximum field of view of the Image capturing optical system is HFOV, a focal length of the image capturing optical system is f, and the following conditions are satisfied:

1.10 <TL /EPD<2.20;

0.84≤tan(HFOV)<1.20; and

0.75 <f /EPD<1.65.

21. The image capturing optical system of claim 20 , wherein the third lens element has positive refractive power.

22. The Image capturing optical system of claim 20 , wherein the seventh lens element has negative refractive power; the image capturing optical system further comprises an aperture stop, wherein an axial distance between the aperture stop and the image-side surface of the seventh lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element is TD, and the following condition is satisfied:

0.80< SD/TD< 0.98.

23. The image capturing optical system of claim 20 , wherein the focal length of the Image capturing optical system is f, the entrance pupil diameter of the image capturing optical system is EPD, and the following condition is satisfied:

0.85 <f /EPD<1.55.

24. The image capturing optical system of claim 20 , wherein each of at least three of the seven lens elements has an Abbe number smaller than 25.0.

25. The Image capturing optical system of claim 20 , wherein the axial distance between the object-side surface of the first lens element and the Image surface is TL, a maximum image height of the image capturing optical system is ImgH, the focal length of the Image capturing optical system is f, a focal length of the second lens element is f2, and the following conditions are satisfied:

TL /Img H <2.0;

TL< 7.5 mm; and

0.40<| f/f 2|<1.20.