When the new range of Canon's mirrorless full-frame was launched, the R series (currently comprising R EOS and EOS RP) made their appearance a series of Canon RF targets. These are new solutions that enable the project to make the most of its intrinsic features.
In addition to having a revolutionary optical design, one of the novelties of Canon RF lenses was to have some integrated functions. For instance, we can find a control ring (Control Ring) on all of them that allows different functions to be performed.
The control ring on Canon RF lenses (also present on one of the adapters) allows the user to modify the aperture, ISO sensitivity and shutter speed "on the fly" without having to move his hands on the camera body and thus theoretically speed up operations.
A mechanism has been inserted to allow more accurate control that issues a "click" for each pitch of the ring so that the user knows that he has modified the parameter concerned.
Now, at least in the USA, the control dial can be silenced. As explained on the official support page, the Canon support service will change the lens for $79.99 in order to avoid the "click" (it will change the adapter instead for $59.99).
The modification is especially useful for those who use the new video recording cameras, as the ring noise can be noticed in the recording. Whether this change will be available in other markets, like the Italian one, is not yet clear. In any case, keep an eye on the Japanese company's support page for those who need to modify their Canon RF lens.