Patent ID: 11947091
Assignee: ZHEJIANG DAHUA TECHNOLOGY CO., LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A zoom lens comprising, in order from an object side to an image side:
a first lens group;
a second lens group;
a third lens group;
a fourth lens group; and
a fifth lens group;
wherein the zoom lens satisfies the following conditions:

−2.28≤f2/fw′≤−1.08

0.15/mm≤TTL/(BFL*fw′)≤0.45/mm

wherein f2 denotes a focal length of the second lens group, fw′ denotes a focal length of the zoom lens at a wide angle end, TTL denotes a total track length of the zoom lens, and BFL denotes a back focal length of the zoom lens,

wherein
the first lens group includes, in order from the object side to the image side:
a first lens having negative refractive power;
a second lens having positive refractive power; and
a first lens unit having positive refractive power, wherein the first lens unit includes a third lens having positive refractive power;

the second lens group includes, in order from the object side to the image side:
a fourth lens having negative refractive power;
a fifth lens having negative refractive power; and
a second lens unit having positive refractive power; and

the third lens group includes, in order from the object side to the image side:
a sixth lens having negative refractive power;
seventh lens having positive refractive power; and
a third lens unit having positive refractive power.