US 12,352,938 B2
Variable magnification optical system, optical device, and method for manufacturing variable magnification optical system
Tomoki Ito, Kawasaki (JP)
Assigned to Nikon Corporation, Tokyo (JP)
Filed by Nikon Corporation, Tokyo (JP)
Filed on Jan. 1, 2024, as Appl. No. 18/401,665.
Application 18/401,665 is a continuation of application No. 17/359,927, filed on Jun. 28, 2021, granted, now 11,899,189.
Application 17/359,927 is a continuation of application No. 16/338,736, granted, now 11,079,575, issued on Aug. 3, 2021, previously published as PCT/JP2017/037354, filed on Oct. 16, 2017.
Claims priority of application No. 2016-204448 (JP), filed on Oct. 18, 2016.
Prior Publication US 2024/0134172 A1, Apr. 25, 2024
Prior Publication US 2024/0231060 A9, Jul. 11, 2024
Int. Cl. G02B 15/14 (2006.01); G02B 13/00 (2006.01); G02B 15/20 (2006.01)
CPC G02B 15/145113 (2019.08) [G02B 13/009 (2013.01); G02B 15/20 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A variable magnification optical system comprising, in order from an object side: a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group and a fifth lens group;
upon varying a magnification, distances between the neighboring respective lens groups being varied and the second lens group and the fourth lens group being moved along an optical axis;
the first lens group comprising, in order from the most object side, one cemented lens and one single lens;
the third lens group including a plurality of positive lenses; and
the following conditional expression being satisfied:
1.00<f3/(−f2)<4.20
where f2 denotes a focal length of the second lens group and f3 denotes a focal length of the third lens group.