RF lenses on other cameras

joenj wrote:

gazza73 wrote:

Are all lenses designed for mirrorless practically the same then and no room for adapters?

Flange range of Sony E-mount is 18mm. Canon RF is 20mm. So, while an RF lens on a Sony E-mount camera could be possible, a Sony E-mount lens on a Canon RF mount camera is not.

Flange distance is only one part of the story. There are also:

1) The mount diameter, which is 54mm for RF and 46mm for E, meaning that an RF-E mount adapter has to expand 3mm on all sides in a space of 2mm to allow the adapter to physically fit on the RF mount lens. And then there is the matter of the RF mount lenses being optically designed around having such a large opening--it is likely that such an adapter would cause really ugly vignetting on any native RF lens. (Third party lenses are probably OK, as they would almost always be designed with either DSLR mounts or E mount in mind.)

2) Flange-back distance. RF lenses are sometimes designed with a significant amount of optics behind the mount bayonet--the rear element of the RF 35mm, for example, protrudes several millimeters backwards. In other words, such a lens needs to protrude into the body of an E mount camera when adapted. Good luck getting that to work, especially combined with the previous point.

If anything, the other way around--E mount lenses on RF--is more likely. The E mount is narrower by 6mm than the RF mount, and there is copious amount of empty space inside the RF mount cavity (which is sometimes used by native RF lenses, as mentioned earlier.) This space may, in theory, allow for an E-RF mount adapter to be sunk into the mount cavity. I doubt we would ever see such an adapter, both for technical and commercial reasons*, but it appears to be physically not impossible.

* Sigma and Tamron are all but certain to offer RF mount versions of their lenses in the near future, and the only real reason to use Sony lenses over EF or RF equivalents in the foreseeable future is if you already have a set of E mount lenses (Canon lenses are at least equal to Sony ones in most cases, and often cheaper). And if you do have a bunch of Sony lenses, why not just use a Sony body?