Is there an adapter to use RF lenses on the EF mount?

[Norm5353]

I have a E2000D with ef mount.  I was given a 70-200mm lens in very good condition however it is an r mount from a newer camera.  Is there an ef to r mount adapter and if so any pointers on which to get.

[kvbarkley]

Currently there are no adapters to use RF lenses on EF bodies.

[deebatman316]

I would suggest looking into the EOS R series camera lineup. It is physically not possible to adapt an RF Mount lens on an EF Mount camera. RF Mount lenses sit closer to the image sensor than an EF Mount lens would. This isn't physically possible. 

[AtticusLake]

There is no adapter, and no adapter is possible -- the RF lens needs to be closer to the sensor than the mount on the front of your EF-S camera.  This is impossible.  (This is "flange focal distance".)  Shame, because that's a nice lens.  But if you want to use it, you'll need a new camera -- this might cost less than the lens, so it could be a good choice.

If you want to know more about lens compatibility, I wrote an article about it:

https://moonblink.info/MudLake/gear/lenses

[mircopolo]

This is actually not true. It is absolutely possible to install RF lens on EF mount body as well as EF-S on EF. But of course you won't be able to use it in such configuration. Just not enough room to fire mirror. This may be the reason that adapters for that conversion are non existing...

[AtticusLake]

I don't know what you mean by "install".  Do you mean with hot glue and duct tape?  Then yes, I guess, though it won't be able to focus.  My point is that there is no manufactured adapter to allow you to do this, and it's for the same reason -- if there was such an adapter, then lens wouldn't be able to focus.

The reason is that the flange focal distance of an RF lens is 20mm, and the EF lens mount is 44mm from the sensor.  If you don't know what "flange focal distance" is, then maybe you should read that article I linked to.

But if you did have such an adapter, then it would NOT interfere with the operation of the mirror -- the adapter would be in front of the mirror.

Unless you're suggesting that an adapter could allow the RF lens to protrude back through the EF lens mount?  In which case, no, this is not possible.  The throat diameter of an EF mount is 54mm, and the outside diameter of an RF lens's bayonet is 53mm, so that leaves virtually no room for an adapter.  In any case the RF lens would have to stick back 24 mm into the EF lens mount, and the RF lenses I own get way wider at that point.

So I'm afraid this has nothing to do with the mirror; you need to read about flange distance.

BTW if you're thinking that an adapter could alter the flange distance with lens elements of its own -- this is called a dioptre adapter, and they do exist, but the general consensus seems to be that the image quality is terrible, so you'd be better off buying a cheap compact camera.

[ebiggs1]

" It is absolutely possible to install RF lens on EF mount body as well as EF-S on EF. But of course you won't be able to use it in such configuration."

Why would you even say that? It doesn't even make any sense. BTW, who would ever buy such an adapter if it were possible which I also don't think it is? Not many I am sure.

[mircopolo]

You are absolutely right. Never have seen adapter like this. But it would be possible to design one and make on printer, plastic of course...For what? I don't know, maybe to prove it is possible, or for some kind of display? Sorry, I know better then that, it has no sense at all...🤔

[kvbarkley]

The problem is that since there is no mirrorbox, EF lenses sit farther from the sensor than RF lenses. The EF-RF adapters essentially replace the mirrorbox so the EF lens is the correct distance from the RF sensor.

Contrariwise, any adapter for an rf lens on an ef body would be way too far to allow for focusing at all distances.

So you could do it, but it would not perform correctly.