The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 1989
Filed:
Feb. 27, 1987
Yasuhisa Sato, Kanagawa, JP;
Yasuyuki Yamada, Tokyo, JP;
Hiroki Nakayama, Kanagawa, JP;
Kouji Oizumi, Kanagawa, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A photographic optical device of this invention comprises: a master lens unit having a positive refractive power, determining a photographic optical path and moving along the optical axis to change magnification; a first auxiliary lens unit having a positive refractive power and being capable of being placed on and off the optical path; and a second auxiliary lens unit having a negative refractive power and being capable of being placed on and off the optical path. The first auxiliary lens unit is attached to an image-plane side of the master lens unit to form a photographic unit giving a low ratio of magnification. The second auxiliary lens unit is attached to an image-plane side of the master lens unit to form another photographic unit giving a high ratio of magnification. The first and second auxiliary lens units are placed outside of the optical path to form another photographic unit giving a middle ratio of magnification.