An Olympus-made Vivitar lens on a Yashica. How do you know it was made by Olympus? What is the serial #?
Vivitar Serial Number Prefix Codes
09 (or 9) Cosina Company, Ltd. [1][2]
13 Schneider Kreuznach [1][2]
22 Kino Precision [1][2]
25 Ozone Optical Co., Ltd.[1][2]
28 Komine Co., Ltd. [1][2][3]
32 Makina Optical Co., Ltd [1][2]
33 Asanuma & Co., Ltd [1][2]
37 Tokina Optical Company, Ltd [1][2][4]
42 Bauer [1][2] (possibly Bauer trademark holder Robert Bosch GmbH)[5]
44 Perkin-Elmer [1][2]
47 Chinon Industries, Inc. [1][2]
51 Tokyo Trading [1][2] (possibly a corruption of Tokyo Koki, a Tokina predecessor)[4]
56 Kyoei Shoji Company, Ltd.[1][2]
61 Samyang Optics Co., Ltd [1]
75 Hoya Corporation [1][2]
77 Kobori Mfg Co. Ltd [1]
81 Polar [1][2]
My favorite 300mm is an APO Sigma f4.5. VERY sharp.