US 11,949,973 B2
Attachment optical system, optical system, image pickup apparatus, image pickup system, and manufacturing method of optical system
Yoshiyuki Taki, Tochigi (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Aug. 10, 2022, as Appl. No. 17/884,783.
Claims priority of application No. 2021-133339 (JP), filed on Aug. 18, 2021.
Prior Publication US 2023/0072113 A1, Mar. 9, 2023
Int. Cl. H04N 23/55 (2023.01); H04N 23/51 (2023.01)
CPC H04N 23/55 (2023.01) [H04N 23/51 (2023.01)] 12 Claims
OG exemplary drawing
 
1. An attachment optical system attachable to and detachable from an imaging optical system, the attachment optical system comprising:
a first converter optical system attachable to an object side of the imaging optical system; and
a second converter optical system attachable to an image side of the imaging optical system,
wherein the first converter optical system includes a first unit consisting of a dome-shaped cover, and
wherein the following inequality is satisfied:
0.9<|skcw/skmw|<1.5
where skcw is a distance on an optical axis from a lens surface closest to an image plane of the imaging optical system to the image plane while the attachment optical system is attached to the imaging optical system in water, and skmw is a distance on the optical axis from the lens surface closest to the image plane of the imaging optical system to the image plane while the attachment optical system is not attached to the imaging optical system in air.