Some new Sigma telephoto patents have been found. You can check them out below: JP 2023-170 [Publication date] 2023-01-04 [Title of Invention] Imaging Optical System [Application date] 2021-06-17 [Applicant] [Identification number] 000131326 [Name] Sigma Corporation Kind Code: A1 To provide an imaging optical system suitable for a compact and lightweight telephoto lens by having a … Continue reading Sigma 500mm F5.6 OS, 700mm F8 OS, and 400mm F5 OS Patents Found