Patent ID: 11914222
Assignee: ZHEJIANG SUNNY OPTICS CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 12:
13. An optical imaging system, sequentially from an object side to an image side of the optical imaging system along an optical axis, comprising:
a first lens having refractive power;
a second lens having negative refractive power;
a third lens having negative refractive power;
a fourth lens having refractive power; and
a fifth lens having refractive power,
wherein 1.0<ETL/EIN<1.5,
where ETL is a distance from an object-side surface of the first lens to an imaging plane of the optical imaging system parallel to the optical axis at ½ of an entrance pupil diameter of the optical imaging system, and EIN is a distance from the object-side surface of the first lens to an image-side surface of the fifth lens parallel to the optical axis at ½ of the entrance pupil diameter of the optical imaging system.