Optical system, camera module, and electronic device

1. An optical system, comprising, successively in order from an object side to an image side:

a first lens having a refractive power, an object side surface of the first lens being concave at a paraxial area thereof, and an image side surface of the first lens being convex at the paraxial area thereof;

a second lens having a positive refractive power, an object side surface of the second lens being convex at a paraxial area thereof, and an image side surface of the second lens being concave at the paraxial area thereof;

a third lens having a positive refractive power, and an image side surface of the third lens being convex at a paraxial area thereof;

a fourth lens having a negative refractive power, and an object side surface of the fourth lens being concave at a paraxial area thereof;

a fifth lens having a refractive power;

a sixth lens having a negative refractive power, and an object side surface of the sixth lens being concave at a paraxial area thereof;

a seventh lens having a positive refractive power, and an object side surface of the seventh lens being convex at a paraxial area thereof; and

an eighth lens having a negative refractive power, an object side surface of the eighth lens being convex at a paraxial area thereof, and an image side surface of the eighth lens being concave at the paraxial area thereof.

2. The optical system according to claim 1 , satisfying the following condition:

TTL/Imgh< 1.36;

wherein TTL is a distance from the object side surface of the first lens to an imaging surface of the optical system on an optical axis, and Imgh is half of a diagonal length of an effective imaging area of the optical system on the imaging surface.

3. The optical system according to claim 2 , satisfying the following condition:

1.29≤ TTL/Imgh≤ 1.30.

4. The optical system according to claim 1 , satisfying the following condition:

2< f/R 16<4;

wherein f is an effective focal length of the optical system, and R16 is a radius of curvature of the image side surface of the eighth lens at an optical axis.

5. The optical system according to claim 4 , satisfying the following condition:

3.72≤ f/R 16≤3.89.

6. The optical system according to claim 1 , satisfying the following condition:

FNO≤2;

wherein FNO is an f-number of the optical system.

7. The optical system according to claim 6 , satisfying the following condition:

1.78≤FNO≤1.88.

8. The optical system according to claim 1 , satisfying the following condition:

1< SD 12 /SD 21<1.4;

wherein SD12 is a maximum effective semiaperture of the image side surface of the first lens, SD21 is a maximum effective semiaperture of the object side surface of the second lens.

9. The optical system according to claim 8 , satisfying the following condition:

1.276≤ SD 12/ SD 21≤1.308.

10. The optical system according to claim 1 , satisfying the following condition:

TTL/f< 1.65;

wherein TTL is a distance from the object side surface of the first lens to an imaging surface of the optical system on the optical axis, and f is an effective focal length of the optical system.

11. The optical system according to claim 10 , satisfying the following condition:

1.58≤ TTL/f≤ 1.61.

12. The optical system according to claim 1 , satisfying the following condition:

tan( HFOV )>1.09;

wherein HFOV is half of a maximum angle of field of view of the optical system.

13. The optical system according to claim 12 , satisfying the following condition:

1.24≤tan( HFOV )≤1.25.

14. The optical system according to claim 1 , satisfying the following condition:

0< T 23 /CT 3<0.9;

wherein T23 is a distance from the image side surface of the second lens to an object side surface of the third lens on an optical axis, and CT3 is a thickness of the third lens on the optical axis.

15. The optical system according to claim 14 , satisfying the following condition:

0.80≤ T 23 /CT 3≤0.82.

16. The optical system according to claim 1 , further comprising a stop arranged between the second lens and the third lens.

17. The optical system according to claim 1 , wherein each lens in the optical system is made of plastic.

18. The optical system according to claim 1 , wherein an object side surface and an image side surface of each lens in the optical system are aspherical.

19. A camera module, comprising:

a photosensitive element; and

the optical system according to claim 1 , wherein the photosensitive element is arranged on the image side of the optical system.

20. An electronic device, comprising:

a fixing member; and

the camera module according to claim 19 ,

wherein the camera module is provided on the fixing member.