Apart from a Laowa 12mm f/2.8 Zero-D Lens, all the lenses I use with my Canon R6 are Canon RF or EF lenses. The Laowa is a special case: being an extreme wide angle, auto focus is not necessary; but generally it has never occurred to me to look for a non OEM lens. I have no problem with the RF16, 35, 85, and 24-240 non L lenses that I have: when used with raw shooting and PhotoLab, they give me excellent results. (I also have an RF50, which I dont care for; this is because, after many years trying, I just have to admit that I dont find that focal length at all useful.)
Because they (Canon) are the biggest player in the industry and their R5 is a HUGE hit. Why let competitors in on that gravy train? Have you seen what they're charging for RF lenses? Why give up all that money when they clearly don't have to?
I suspect that even for Canon the development of a complete new range of cameras and lenses, with very little commonality with the DSLRs, was a big investment. Keeping hold of the lens sales for a while probably seemed to be a good way of getting return on investment.
The only way that 3rd party RF lens sales could positively impact Canon’s profitability is by making Canon’s bodies more appealing (increasing body unit sales). The flip side is that Canon does not directly profit from any of those 3rd party lens sales, and in fact loses their own potential sales (profits) for each and every 3rd party lens that gets sold.
Introducing a new closed RF mount provides Canon with the opportunity to benefit from all RF (autofocus) lens sales. A much more profitable business model, even if some potential body sales are indeed lost (due to 3rd party lens availability elsewhere). Now the Canon Imaging Division had two primary goals to meet in order for this new business model to work. #1 To produce a hit lineup of extremely capable (and popular) new mirrorless bodies to counter any 3rd party influence on unit sales. And #2 to fill out their RF lens lineup with enough popular models beyond the critical market segments that were initially targeted in the first few years of RF lens development.
By most measures Canon has been successful in achieving (and perhaps exceeding) goal #1 thus far. Now the only task left is goal #2, which is for Canon child’s play. Fill a gap here, one there, and rake in 100% of the lens revenues that would have been lost had they followed the old business model. Canon’s place in the market can only be stronger for this. And I think the consumer will benefit from the increased R&D and Production resources that can now be directed toward all future Canon products. From my POV the future is looking pretty darn bright!
Patents are all unique and I’m no lawyer. I assume there has to be some kind of special proprietary knowledge to be granted one. So something like windshield wipers aren’t especially unique and I’d guess many auto makers actually use suppliers for them and don’t manufacture them themselves. You can bet if they invented a new magic rain repellent glass that stayed dry and clear no matter the weather, it would be patented for a while.
The RF mount itself is just a simple part that locks a lens into place with a turn. Again, no special knowledge and that’s not what’s patented. Evidence for that is the number of manual focus third party RF lenses.
Funny you mention batteries. Canon does have proprietary batteries that provide better, more accurate feedback to users when used in Canon Cameras. The communication between camera body and battery gives more accurate info about battery life and such. Off brands work. But don’t give as accurate feedback. I’ve heard some users complain that they go from working to empty with no warning. Some are better than others but OEM is the best. But a battery itself is well known tech that’s very old and not under patent.
Clearly the communication protocol is something special, unique, and new enough that a patent was granted.
As far as bodies go, I guess you’re just being facetious. There are lots of manufacturers of camera bodies and the general idea of a camera body is well over 100 years old. No special knowledge. Canons DPAF system is proprietary and likely under patent so that’s why all these manufacturers use slightly different systems implemented in a slightly different way. You can bet they’d sue if they discovered someone used their autofocus system in a way that violated a patent. Doesn’t mean there aren’t other ways to have auto focus.
According to this website, Canon has recently licensed use of the RF protocol with autofocus to a small company. Meike is advertising an 85mm f/1.4 lens.
Canon did not tell their lens competitors something as broad as "do not make RF lenses". They just said to do not make autofocus RF lenses without a license for the Canon patent for the newly invented novel autofocus protocol. Canon has an invention that never was existed before involving the method of the specific protocol used in the RF lenses. Reverse engineering designs for autofocus may infringe that patent.
I was using Canon from 1991 and for a number of years nearly all of the "compatible lenses" were very poor quality IMO. This includes Sigma and Tamron. I bought some of those early and I was very disappointed. Maybe by 2008 these lenses IMO had improved enough so that would not be disappointed. I began buying a couple while most of my lenses were Canon and many of those were L grade. I learned to love L grade lenses over time. L grade lenses have always been expensive but I began to realize over they their lifetime for me L grade lens were good value.
So I would say 21 years after 1987 is the answer to your question. I own 25 L grade and RF lenses now along with five Sigma and one Tamron. Several of my Sigma lenses are ART lenses which are incredibly sharp but big and heavy. I have a big and heavy 120-300mmf2.8 Sigma zoom that gave me capabilities Canon did offer.
