US 12,066,598 B2
Optical system, lens apparatus, and image capturing apparatus
Yuki Shinzato, Tochigi (JP)
Assigned to Canon Kabushiki Kaisha, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Feb. 9, 2022, as Appl. No. 17/667,919.
Claims priority of application No. 2021-019102 (JP), filed on Feb. 9, 2021.
Prior Publication US 2022/0252840 A1, Aug. 11, 2022
Int. Cl. G02B 13/00 (2006.01); G02B 9/12 (2006.01)
CPC G02B 13/0035 (2013.01) [G02B 9/12 (2013.01); G02B 13/006 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An optical system comprising, in order from an object side to an image side:
a first lens unit consisting of one or more negative lenses;
a second lens unit with positive refractive power disposed so as to have a first air space from the first lens unit; and
a third lens unit disposed so as to have a second air space from the second lens unit,
wherein the first air space is a widest air space of air spaces formed closer to the object side than a positive lens disposed closest to the object side in the optical system,
wherein a surface of the first lens unit closest to the image side is concave,
wherein the third lens unit consists of a lens element with negative refractive power and having a concave surface on the object side, and
wherein the following inequalities are satisfied;
0.08<x1/TTL<0.35
0.08<x2/TTL<0.25
0.10<fL1/fL3<0.50
where x1 is an on-axis length of the first air space in focusing on an object at infinity, x2 is an on-axis length of the second air space in focusing on an object at infinity, TTL is an overall optical length of the optical system in focusing on an object at infinity, fL1 is a focal length of the first lens unit in focusing on an object at infinity, and fL3 is a focal length of the third lens unit in focusing on an object at infinity.