Mount RF lens on EOS M series cameras?

TL;DR: Is there an adapter for mounting an RF 70-200mm on an EOS M6 mk II?

At the moment, I have three types of Canon cameras; DSLR, M series mirrorless, and R series mirrorless. I want to replace my EF lenses with RF lenses over time. One challenge I can see is the compatibility of RF lenses with the M series cameras. I use the M6MKII camera for light travel with the full range of EF-M zoom lenses. But I also use it as a spare action camera since it has decent fps (and faster than any of my DSLRs).

If I have understood the flange focal distance debate correctly, there's a 2 mm difference between the two mounts. And an adapter similar to the EF-RF adapters but only 2 mm should theoretically work.

Apologies if this has been asked before. I have searched for an answer, and everything I have found dealt with EF-M lenses on R series cameras. I have no interest in that.

Doesn't look like it.

https://www.reddit.com …canon_efm_to_rf​_adapters/

https://breakfastograp​her.wordpress.com …m-to-rf-adapter-possible/

Lou

The way I understand those articles, they are referring to using EF-m on RF cameras.

No. An RF lens cannot be adapted for use on and M-series camera.

Likewise, an EF-M lens cannot be adapted for use on an R-series camera (or, for that matter, on anything else).

EF/EF-S lenses can be adapted for use on either R-series or M-series cameras.

The problem is the "lens register" of the two mirrorless cameras are not the same, but very similar. One is 20mm while the other is 18mm, if memory serves. This leaves no room for an adapter to be fitted. In addition, the diameter of the RF-mount is larger than the EF-M mount.

Lens register is also called "flange to focal distance" or "FFL". This is the distance the lens is designed to back-focus upon. The sensor or film plane of the camera. The "flange" is the outer face of the bayonet mount on the camera (screw mount in some legacy systems).

EF/EF-S lenses are designed with 44mm FFL. As a result, there is plenty of room with them, to adapt them to either RF or EF-M camera. The adapter "adds" about 1" of lens (24mm in one case, 26mm in the other) to the back of the lens, to correctly position it for use on the mirrorless camera.

Here is a pretty good illustration of this: https://briansmith.com​/flange-focal-distance-guide/

Notice the focal plane of the mirrorless camera (in this case a Sony e-mount). Lenses designed with that short FFL would need to be fitted inside a DSLR, in order to focus properly! Obviously, that's impossible. In some cases there are adapters that have optical elements to "correct" for more minor differences. But nothing as extreme as this example, and the added optics often aren't great for image quality.