Patent ID: 11953756
Assignee: JIANGXI OFILM OPTICAL CO., LTD.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 8:
9. An optical system, successively in order from an object side to an image side, comprising:
a first lens having a positive refractive power, an object side surface of the first lens being convex at a circumference thereof;
a second lens having a refractive power;
a third lens having a refractive power;
a fourth lens having a refractive power;
a fifth lens having a refractive power;
a sixth lens having a positive refractive power;
a seventh lens having a negative refractive power, an image side surface of the seventh lens being concave at an optical axis; and
an eighth lens having a negative refractive power,
wherein the optical system satisfies the following conditions:

1<TTL/L<2.5;

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 the optical system further comprises a stop, L is an effective aperture diameter of the stop; and

8<|R7+R8|/|R7−R8|<48;

wherein R7 is a radius of curvature of an object side surface of the third lens at the optical axis, and R8 is a radius of curvature of an image side surface of the third lens at the optical axis.