US 11,940,606 B2
Optical system and imaging apparatus having the same
Shuichi Mogi, Tochigi (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Nov. 17, 2022, as Appl. No. 17/988,962.
Application 17/988,962 is a continuation of application No. 17/146,688, filed on Jan. 12, 2021, granted, now 11,536,934.
Claims priority of application No. 2020-006584 (JP), filed on Jan. 20, 2020.
Prior Publication US 2023/0080985 A1, Mar. 16, 2023
Int. Cl. G02B 15/14 (2006.01); G02B 27/00 (2006.01); G02B 27/64 (2006.01)
CPC G02B 15/142 (2019.08) [G02B 27/005 (2013.01); G02B 27/646 (2013.01)] 30 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 first focus lens unit having a negative refractive power; and
a second focus lens unit having a positive refractive power,
wherein the first lens unit is fixed during focusing,
wherein the first focus lens unit and the second focus lens unit move so that a distance between the first focus lens unit and the second focus lens unit changes during focusing,
wherein the first lens unit includes a single lens which is disposed closest to an object and has a negative refractive power, and
wherein the following inequality is satisfied:
2.20<ff2/bf<12.00
where ff2 is a focal length of the second focus lens unit, and bf is a back focus of the optical system.