Excuse me, but if Tamron or Sigma produce RF lenses for APS-C, they're capable of doing the same for full-frame RF.EF mount was never open, it was reverse engineered by the likes of Sigma and Tamron. It's a much simpler protocol than RF.
And back then the third party manufacturers only made low quality and cheap lenses that often could not focus properly. So they were not really a threat for Canon. Today Sigma and Tamron make amazing quality lenses and Chinese manufacturers getting better and better.
I think Sony might be in the situation soon to be able to sell only camera bodies and professional Sony lenses to people will lots of $$$. Everyone else will just use Sigma, Tamron or Chinese lenses.
So, it's Canon that's blocking them.
And I don't think anyone makes better lenses than Sony. It's just that there are different needs to be met.
Upvote
0