US 12,235,423 B2
Variable magnification optical system, optical apparatus, and method for producing variable magnification optical system
Kosuke Machida, Tokyo (JP)
Assigned to Nikon Corporation, Tokyo (JP)
Filed by Nikon Corporation, Tokyo (JP)
Filed on Sep. 29, 2023, as Appl. No. 18/375,375.
Application 18/375,375 is a division of application No. 17/406,070, filed on Aug. 18, 2021, granted, now 11,796,776.
Application 17/406,070 is a division of application No. 16/496,446, granted, now 11,143,851, issued on Oct. 12, 2021, previously published as PCT/JP2017/014194, filed on Apr. 5, 2017.
Prior Publication US 2024/0061221 A1, Feb. 22, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 15/14 (2006.01); G02B 5/00 (2006.01); G02B 13/00 (2006.01); G02B 13/02 (2006.01); G02B 13/06 (2006.01); G02B 13/18 (2006.01); G02B 15/163 (2006.01); G02B 15/177 (2006.01); G02B 15/20 (2006.01)
CPC G02B 15/144511 (2019.08) [G02B 13/18 (2013.01); G02B 15/163 (2013.01); G02B 15/177 (2013.01); G02B 5/005 (2013.01); G02B 13/0045 (2013.01); G02B 13/009 (2013.01); G02B 13/02 (2013.01); G02B 13/06 (2013.01); G02B 15/20 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A variable magnification optical system comprising:
a plurality of lens groups;
upon varying a magnification from a wide angle end state to a telephoto end state, distances between adjacent lens groups being varied;
said plurality of lens groups comprising, in order from an object side, a first lens group having negative refractive power, a first intermediate lens group comprising at least one lens group and having positive refractive power, a second intermediate lens group comprising at least one lens group, and a rear lens group comprising a plurality of lens groups;
upon varying the magnification from a wide angle end state to a telephoto end state, the first lens group being moved along the optical axis, a distance between the first lens group and the first intermediate lens group being varied, a distance between the first intermediate lens group and the second intermediate lens group being varied, and a distance between the second intermediate lens group and the rear lens group being varied;
a most object side lens group in the rear lens group being a focusing lens group and is moved upon carrying out focusing from an infinite distance object to a close distance object; and
the following conditional expressions being satisfied:
0.50<(−f1)/f1Rw≤0.994
0.80<|fF|/ft≤1.402
where f1 denotes a focal length of the first lens group, f1Rw denotes a composite focal length of all lens groups behind the first lens group in the wide angle end state, fF denotes a focal length of a focusing lens group having a strongest refractive power of the at least one focusing lens group, and ft denotes a focal length of the variable magnification optical system in the telephoto end state.