Here\'s the thing, though. I own my camera. I can use it with whatever lenses I want (the third-party AF RF lenses that are not on the market work with it, by the way, and there are a few AF lenses being sold new by Yonguo, apparently). I can modify it, break it, throw it in a woodchipper (if I really wanted to — I don\'t). It belongs to me, not to Canon.
Similarly, third-party manufacturers have the right to sell any legal product whether or not Canon would like them to. I have the right to choose to buy them (even if that\'s not what Canon would recommend).
The rationales that Craig has brought up are all irrelevant:
1. To be clear, Canon isn\'t obliged to provide customer support to users of third-party lenses (even if they get messages from people who buy them) — no more than they\'re obliged to provide support to people who have problems with their Nikon or Sony equipment.
2. If something a lens does doesn\'t work on a future body, that\'s that, of course. Compatibility breakage happened with third-party EF lenses too (look up \"Sigma rechip\" for a good example). Canon can make it clear that they aren\'t responsible for weirdness with third-party lenses. This isn\'t grounds for any sort of IP lawsuit.
(By the way, IBIS didn\'t work with Samyang\'s RF lenses until they put out a firmware update for them! Interestingly, IBIS also doesn\'t work on Sigma lenses with FTM override turned on, so there\'s something funky with how it activates! Nevertheless, uncoordinated IBIS — what\'d be used for most of these lenses, esp. as most don\'t have OIS — shouldn\'t require future adjustments once working.)
3. No third-party EF lens ever supported DLO (including the Sigma lenses that support other in-body corrections on Canon cameras). I don\'t think this is really relevant.
Here\'s the distinction: the things that Craig brings up are perhaps reasons why *Canon* might not want third parties making lenses. They have nothing to do with whether or not Canon is in the right making any legal threats. Those are two very different subjects.
As for the RF mount \"not being a closed mount\": I think that people have a very weird fixation on the terms \"open mount\" and \"closed mount,\" which are used to imply various things about various mounts. Let\'s compare:
- Sony: Gives out full specifications and protocol details — but hobbles lenses in a number of ways (e.g., the 15fps limitation)
- Nikon: Gives out specifications on the condition that Tamron and Sigma only make certain specific lenses (which, not coincidentally, don\'t compete with Nikon\'s)
- Canon: Has given the RF protocols to Voigtländer to make a chipped full-manual lens
I\'d suggest looking at the substance, rather than just saying something is \"open\" or \"not open.\"