	US 11,947,091 B2
	Zoom lens and optical device having the same
Kai Liu, Hangzhou (CN); Faguan Lin, Hangzhou (CN); and Hongxing Ding, Hangzhou (CN)
Assigned to ZHEJIANG DAHUA TECHNOLOGY CO., LTD., Hangzhou (CN)
Filed by ZHEJIANG DAHUA TECHNOLOGY CO., LTD., Zhejiang (CN)
Filed on Nov. 25, 2021, as Appl. No. 17/456,582.
Application 17/456,582 is a continuation of application No. PCT/CN2019/104180, filed on Sep. 3, 2019.
Claims priority of application No. 201910462619.7 (CN), filed on May 30, 2019.
Prior Publication US 2022/0082806 A1, Mar. 17, 2022
Int. Cl. G02B 15/14 (2006.01)

CPC G02B 15/145 (2019.08)

20 Claims

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/f_w′≤−1.08

0.15/mm≤TTL/(BFL*f_w′)≤0.45/mm

wherein f₂denotes a focal length of the second lens group, f_w′ 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.