US 11,726,305 B2
Converter lens, interchangeable lens, and image capturing apparatus
Hiroki Ebe, Utsunomiya (JP); and Shinichiro Saito, Utsunomiya (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on May 9, 2022, as Appl. No. 17/739,974.
Application 17/739,974 is a continuation of application No. 16/796,764, filed on Feb. 20, 2020, granted, now 11,474,332.
Claims priority of application No. 2019-034283 (JP), filed on Feb. 27, 2019; and application No. 2019-210887 (JP), filed on Nov. 21, 2019.
Prior Publication US 2022/0260813 A1, Aug. 18, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 13/16 (2006.01); G02B 9/10 (2006.01)
CPC G02B 13/16 (2013.01) [G02B 9/10 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A converter lens that has a negative refractive power as a whole and is disposed on an image side of a master lens so that a focal length of an entire system becomes longer than a focal length of the master lens alone,
wherein the converter lens consists of a front unit having a positive refractive power and a rear unit having a negative refractive power,
wherein the front unit has a combined refractive power having a maximum positive refractive power in a case where the combined refractive power is obtained by a refractive power of each lens being combined in order from the lens closest to an object to an image side,
wherein the rear unit includes a first subunit and a second subunit,
wherein the second subunit consists of a positive lens closest to the image plane in the rear unit, and
wherein the following conditional expression is satisfied:
1.00<L/(sk×β)<4.00
0.10<f1/(|EXT_f|×β)<0.36
0.132≤fb/(|EXT_f|×β)<0.35
where L is a distance on an optical axis from a lens surface closest to the object in the converter lens to a lens surface closest to the image plane in the converter lens, sk is a distance on the optical axis from a lens surface closest to the image plane in the converter lens to the image plane when the converter lens is disposed on an image side of the master lens, f1 is a focal length of the front unit, EXT_f is a focal length of the converter lens, and fb is a focal length of the second subunit.