Many Canon RF mount shooters have been eagerly awaiting lens competition from Sigma and Tamron. The 3rd party lens makers themselves have talked about this being a desire – if not their hottest priority. But in a wide-ranging interview, a Russian Canon executive told an interviewer, “We have a really closed mount and the company’s position is that the mount is Canon’s own design, and third-party companies remain our competitors.”
While there are already RF mount third party lenses available, they are mostly manual focus lenses for budget or niche lens categories – not the directly competitive lenses Sigma and Tamron could furnish.
A note on information sourced from Russian Canon executives: in the past, Russian and Eastern European executives have been more forthcoming than traditionally staid Western executives, and – certainly – Japanese executives. But there have also been instances where off-the-cuff comments have later proven to be inaccurate.
The RF mount system works seamlessly with EF mount devices, which is likely the route to compatibility third party lense makers would take. Reverse-engineered EF mount capacity is quite widespread. The new RF mount protocols would be a dangerous means for a third party to use, as they are communicated through the contacts at a higher stack layer than the EF comms, which allows for a tightened-up, encrypted communications environment. Even if a company like Sigma could get a lens working on the RF standards, it could not guarantee a later camera firmware upgrade could render the lens useless, where Canon cannot change the existing EF protocols without rendering useless its own legacy lineup.
That EF vs. RF mount difference is an advantage for Canon, where it is using the additional data channels in the RF standard to move accelerometer information and lens controls information that provide real utility that a third party cannot: such as seven or even eight stops of image stabilization when combined with camera IBIS. As a result, Sigma could probably put out an RF 85mm f/1.2 that rivaled Canon’s in sharpness, but it would be unlikely to achieve the same stabilization.
Other notable statements from the interview include the executive’s indication that the M mount series “is well equipped,” when talking about prospects for new camera and lens development. This indicates both that Canon does
not intend to provide updates in the near future, and also that it considers the M system to be relegated to a more casual set of use cases, such as travel and snapshots, which is what the current lens lineup is geared to.