Originally posted by RobA_Oz What’s to stop Sigma reverse-engineering the R-mount, like they did with the various forms of the K-mount?
Legally, nothing.
Just ask IBM, who are very annoyed how the PC thing panned out, they don't even make 'em any more, they got squeezed out of the marketplace by the third parties.
You take a CRO to an RP, and see what comes out of the pins when you press that button, and that one, and focus to infinity, etc.
Assumptions will catch you out in different circumstances, so you'd better promise free firmware upgrades each time a bug is discovered.
I have a Yongnuo lens that's a copy of the Canon 100mm f2, but it doesn't work through my Sony's EF to E mount adapter, I'm forced to use it as a manual lens because they stuffed up somewhere.