Nippon Kogaku (which later changed its name to....Nikon) is the company that Canon turned to when Canon came out with its first camera models...they hired Nikon to make and supply the lenses for their new brand of cameras. Not making this up. Canon always knew where to look for good optical designers and top flight optical manufacturing and assembly...Nikon plants! Canon finally got its own lens line going about three years after they started producing rangefinders, and in the same year, 1948, Nikon began producing 35mm rangefinder cameras, and Canon switched out Nikkors for their own Canon-branded lenses.
Canon's own web materials try to minimize the Nikon lens connection, but they do acknowledge it.Gotta love the shi++y, low-resolution photo of the early Canon rangefinder, deliberately making the NIKKOR lens information on the front ring of the lens totally illegible! In those days, the honor of the lens manufacturer's brand and model number was PLAINLY and BOLDLY engraved on the front of most lenses, wayyyyy out front, where customers could easily see what the lens "was".
History Hall - Canon Camera Story 1946-1954