over the years, Minolta has had a lot of partnerships with other companies in the industry. They made the Minolta CLE with Leica, the Beseler Minolta 45A enlarger with Beseler and of course, had a strong relationship with Konica which eventually lead to the Konica Minolta merger. Minolta also had a strong relationship with Leica and produced most of the Leica R series together.
Why is this? Why did minolta have all these strong ties while the people over at Nikon, produced everything themselves?
Nikon did not produce his own optical glass, unlike Asahi Optical... They had a longstanding collaboration with Bronica for creating the ultimate medium format system: Nikon provided excellent lenses, Bronica provided the unreliability.
Pentax (Asahi) collaborated with Zeiss in the late 70s, the K mount was designed together with Zeiss and one or two lenses (maybe more) were a joint design.
Yashica (Kyocera and Tomioka) made lenses for Zeiss and made the Contax cameras for Zeiss
Zeiss Ikon got together with Voigtlander and they also acquired Rollei. With this powerful combination of three of the best german camera manufacturers they managed to build some of the worst german cameras ever like the Rollei SL35M...
I don't think Canon collaborated with any other company. Maybe because they had so much success with the copier and calculator busineses that they had lots of money to spare in R&D and to spend all the 70s and most of the 80s in how to alienate their customer base by changing the Canon lens mount.