US 12,235,421 B2
Optical system, image pickup apparatus, and lens apparatus
Toyokatsu Fujisaki, Tochigi (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Jan. 21, 2021, as Appl. No. 17/154,143.
Claims priority of application No. 2020-011125 (JP), filed on Jan. 27, 2020.
Prior Publication US 2021/0231929 A1, Jul. 29, 2021
Int. Cl. G02B 15/14 (2006.01); G02B 15/20 (2006.01); G02B 27/00 (2006.01)
CPC G02B 15/143107 (2019.08) [G02B 15/20 (2013.01); G02B 27/0025 (2013.01)] 26 Claims
OG exemplary drawing
 
1. An optical system comprising, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power,
wherein a distance between adjacent lens units changes when focusing,
wherein an aperture stop is disposed between the first lens unit and the second lens unit,
wherein for focusing from infinity to a short distance, the first lens unit-is fixed, and the second lens unit and the third lens unit are moved so that a distance between the second lens unit and the third lens unit changes,
wherein the first lens unit includes a plurality of negative lenses, and
wherein the following inequalities are satisfied:
0.01<f1/f≤2.026
0.70<f2/f3<30.00
where f is a focal length of the optical system in an in-focus state on infinity, and f1, f2, and f3 are focal lengths of the first lens unit, the second lens unit, and the third lens unit, respectively.