ALEXANDRIA, Va., Oct. 28 -- United States Patent no. 12,449,646, issued on Oct. 21, was assigned to Canon K.K. (Tokyo).
"Optical system and image pickup apparatus having the same" was invented by Takeharu Nakada (Tochigi, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "An optical system includes, in order from an object side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power. A distance between adjacent lens units changes during focusing. During focusing from an infinity object to the closest object, the first and third lens units do not move and the second lens unit moves toward the image side....