Patent application for optical systems such as Sigma “18-50mm F2.8-4 OS” and “17-40mm F4 OS” Overview [Public number] P2022158386 [Release date] 2022-10-17 [Title of Invention] Imaging Optical System [Application date] 2021-04-02 [Applicant] [Identification number] 000131326 [Name] Sigma Corporation Kind Code: A1 A compact image forming optical system having a small open F value over the … Continue reading Sigma Lens Patents Found For Sigma 17-40mm f/4 OS and Sigma 18-50mm F2.8-4 OS