I've been keeping an eye out for these. As an EF-M user, it's something I'd appreciate, since Canon (and Nikon) have decided not to make Sony's mistake and cram a full-frame sensor into a mount designed for APS-C.
And it should be possible given that there are no electronics involved, just like the EF -> RF and EF -> EF-M adapters already available. It'll just be very small like the mechanical Nikon F to Canon EF adapters we've seen.
Let us know if you've seen one, mention of one, etc!
I doubt you'll ever see one simply because there are so few EF-M lenses. I see a bunch of sub-$500 slow zooms and a couple of short primes on their site. You'd be better off selling and getting the EF-S equivalents.
Wouldn't that be a reason to make an adapter, though?
I am talking about adapting the new EOS RF lenses with their 20mm flange focal distance to the EOS-M EF-M 18mm flange focal distance. The reverse doesn't make much sense.
[and the appeal of the EOS-M system is that the lenses while slow are also comparatively smaller and lighter than the competition, i.e. Sony E and Fuji X APS-C mirrorless, while also being equal or better in optics]
OK I misread the direction you want to go with the adapter. I guess they could adapt RF lenses to EOS-M cameras but there's so few RF lenses now and they're mostly big beasts. I don't know how many people would really want to mount a 28-70 f/2 on an M body. The others already have EF counterparts that can be adapted. Also, I don't know how much longer EOS-M will be around. Canon hasn't exactly put a lot of effort into building out a lens catalog for it and adapting big lenses to it defeats the purpose of a small system. I suspect Canon is all-in on RF and will likely make an RF-S mount for crop sensors that can take RF or smaller RF-S lenses a la EF-S.
You have 2 mm to fit the RF mount into the EF-M mount. I think the flange of the RF mount is thicker than 2 mm and since the throat of the RF mount is bigger than the throat of the EF-M mount, it will therefore have to sit outside or in front of the EF-M flange.
That would probably mean that to make such an adapter would require more than 2mm flange to flange distance and might not enable infinity focus?
riokid wrote:
Maybe I am not seeing the big picture
You see it. Canon could not have done a better job in making sure the EF-M mount will never use RF mount lenses. They are incompatible with each other and there is zero hope that an adapter will ever be made.
johnctharp wrote:
And it should be possible given that there are no electronics involved, just like the EF -> RF and EF -> EF-M adapters already available.
But there would be electronics involved, since RF has 12-pin comms and EF has 8. It's (relatively) easy to adapt EF lenses to the RF mount because all lens comms and functions are supported on those eight pins, and the extra four on the RF side just aren't used. But the reverse is not true -- RF lenses would "expect" to be able to communicate on all twelve pins and would likely have functionality that depends on them.
moondigger wrote:
But there would be electronics involved, since RF has 12-pin comms and EF has 8. It's (relatively) easy to adapt EF lenses to the RF mount because all lens comms and functions are supported on those eight pins, and the extra four on the RF side just aren't used. But the reverse is not true -- RF lenses would "expect" to be able to communicate on all twelve pins and would likely have functionality that depends on them.
That's why I asked the question!
I just wonder if the four pins are necessary for lens operation.
Also, with respect to the difference in physical mount differences, remember the 18mm for EF-M and 20mm for RF. Yes, the RF mount is of a wider diameter, but I don't see that being a huge problem unless there's something on an EOS-M camera that would get in the way.
johnctharp wrote:
That's why I asked the question!
I just wonder if the four pins are necessary for lens operation.
Also, with respect to the difference in physical mount differences, remember the 18mm for EF-M and 20mm for RF. Yes, the RF mount is of a wider diameter, but I don't see that being a huge problem unless there's something on an EOS-M camera that would get in the way.
Until somebody gets an EOS R and puts some sort of scope/logic analyzer on the whole interface between it and an RF lens, no one knows for sure.
The EF interface is some variant of an 8 bit SPI electronic interface with a Canon proprietary serial command protocol...which makes sense being designed in the mid 1980's with the kind of Motorola microcontrollers available.
The RF interface, well nobody knows yet what the interface is in over those 12 pins--and it's also not clear if the EF protocol is carried over the RF 14 pins the same way. Are there common eight pins to EF? It would make the adapter cheaper. Or is the adapter handling some electronic interface change, like a RS232 to USB serial adapter does? Even if the electronic interface is modified, who knows what the RF command protocol is...
It's also not clear what electronics would be in an RF lens. You'd think that if it was designed for RF mount that the controller onboard would use the full electronic interface and command protocol functions of the RF mount--things like the third control ring and yet unknown abilities. (I think the lenses could report indivdual end of line defect and calibration data back to the body, but that's a guess)
Yet, there's also the possibility the lens electronics designers had to hedge their bets as to when RF launched--so maybe there's a generation of control boards which can speak both RF and EF. We know there are shared control boards over a generation of EF lenses.
Again nobody knows until a very detailed teardown and analysis of an RF lens is done.
johnctharp wrote:
I just wonder if the four pins are necessary for lens operation.
I don’t have any technical/engineering information about the RF mount beyond what Canon has publically disclosed, but it seems unlikely to me that RF lenses would be adaptable to EF or EF-M. The EF mount was advanced for the 1980s, but it’s 30+ tear-old technology now. Why would Canon’s design engineers hamstring the new lenses by making them work with a 30+ year-old mount that physically cannot accomodate them due to incompatible backfocus distance?
I know, the EF-M backfocus distance is short enough. But it’s basically just a variation on EF, and subject to many of the same limitations.
Yes, the RF mount is of a wider diameter, but I don't see that being a huge problem unless there's something on an EOS-M camera that would get in the way.
That’s a distinct possibility, since Canon was touting how the new mount allows for radical new lens designs that take full advantage of the possibilities the mount allows.
Just thought I'd bump this thread for any new thoughts/information. I would love to own an RF-based camera and be able to use those lenses on an EF-M body from time to time.
The alternative is to buy all EF/EF-S lenses and share them between the two bodies.
In other words..."hey Canon...if you want more folks to buy RF lenses, make them compatible with EF-M."
OK...so not THAT many people might wanna do this, but I mean, how much R&D could it take? It's just a piece of metal with some contacts, right? (Well, probably.)
And afterall, I could imagine folks who are choosing between Sony and Canon...they see Sony's lens compatibility between FF and crop-sensor bodies as being a real advantage...even if it's just for people moving UP from crop to FF - they can keep using their crop-based lenses on the FF body til they transition over.
wsalopek wrote:
......
And afterall, I could imagine folks who are choosing between Sony and Canon...they see Sony's lens compatibility between FF and crop-sensor bodies as being a real advantage...even if it's just for people moving UP from crop to FF - they can keep using their crop-based lenses on the FF body til they transition over.
....
It's a double edged sword. While compatibility between FF and APS-C can be attractive, it often results in manufacturers not focusing on APS-C optimized lenses. Just look at Canon EF-M 32mm 1.4 or Sigma 56m 1.4 lenses - these are very compact, fast designs specifically done for APS-C. Would it make any sense to instead use say a Sony 35mm 1.4 FF lens on an APC-S body? It's a beast and costs $1600.
Part of the reason I currently use a Fuji APS-C system (and had an EOS-M system in past) is exactly because the lenses are high quality lenses optimized for APS-C.
I can't see the real need for RF-EF-M as someone who has just started with R cameras I'm very unlikely to buy new RF lenses other than the one that cam with the camera as I will use the EF/EF-S lenses on both the R and the M series cameras.
I only bought the M50 after having left my camera bag at home whilst going on a trip when the Taxi arrived early and I needed something with wide to at least 250mm lens. The M50 was a great buy it works well and when attached to an L series or Sigma sport produces some great images.
If your moving from M to RF then you may want to use the M lenses on the R camera but they are so small that you would almost certainly get barreling as you do when fitting an APS-C lens to a full frame camera such as a Tamron Dii EF mount to a 5D.
So I've looked at this as well, and can't see a way to make such an adapter. (If it could be done easily, the 3rd parties would already have it.)
Many posit that this means the death of EF-M. But at the same time, many posit (with more basis in reality) the death of SLR.
So do we think canon will be RF only in ten years?
I did come up with this cockamamie scheme;
Current EF-M bodies have no option, but future M bodies could instead of having an EF-M mount, have a larger bayonet into which either an EF-M mount or an RF mount could be installed.
reggraham wrote:
I can't see the real need for RF-EF-M as someone who has just started with R cameras I'm very unlikely to buy new RF lenses other than the one that cam with the camera as I will use the EF/EF-S lenses on both the R and the M series cameras.
I only bought the M50 after having left my camera bag at home whilst going on a trip when the Taxi arrived early and I needed something with wide to at least 250mm lens. The M50 was a great buy it works well and when attached to an L series or Sigma sport produces some great images.
If your moving from M to RF then you may want to use the M lenses on the R camera but they are so small that you would almost certainly get barreling as you do when fitting an APS-C lens to a full frame camera such as a Tamron Dii EF mount to a 5D....Show more →
Arguably, M lenses can not be mounted to R at all. It's the wrong direction. The only way would be if the r mount is large enough diameter to allow an M mount to be recessed into it closer by 2mm. RF is 54mm dia, M is 47mm dia, I suppose it might be possible to make such a thing, but with only 3.5mm on the wall before you start cutting bayonet thread into both sides? Seems unlikely.
There will never be an RF to EFM mount adapter. The very fact that Canon designed the R mount cameras to be ever so slightly different the M mount means Canon knew that they would be creating an APS-C R mount camera in their model roadmap.
TeamSpeed wrote:
There will never be an RF to EFM mount adapter. The very fact that Canon designed the R mount cameras to be ever so slightly different the M mount means Canon knew that they would be creating an APS-C R mount camera in their model roadmap.
With a few years of hindsight, this is the conclusion I'm coming to as well.
Given the technical possibility, Canon could have already introduced an adapter to put RF lenses on EOS-M cameras.
They could even have upgraded the EF-M mount to a hypothetical 'RF-M' mount that keeps backward compatibility with existing EF-M lenses but adds full support for RF lenses as well as support for future lenses using the APS-C mount that could be designed with the additional features of the RF system.
They didn't do that. They even made RF so close to being physically impossible to adapt that it seems like they may have even went out of their way; that they may have gone further to the point of making it physically impossible, but ran into a separate design limitation that kept them from going 'all the way'.
The theories that Canon will continue to evolve the EOS M system are getting really hard to support. It's a stretch to suggest that Canon perhaps made the RF mount almost physically impossible to adapt to EF-M because they wanted to be the only ones that could pull it off, for example.
But the big one is this: the only reason to avoid the notion of using RF lenses on EOS M cameras is that they don't want to send the message that they're going to keep developing EOS M to pair with RF like EF-S was with EF, because instead they're going to release an APS-C RF-mount camera at some point.
Which is frustrating but unfortunately the most likely alternative.
I know I am in a minority here, but personally I don't see Canon abandoning EOS-M mount in favor of APS-C RF bodies. RF mount diameter is large enough that it will make it impossible to create small bodies like M200. The slightly larger M6 II class bodies are also not likely unless the bayonet extends till the top edge of the camera.
So switching to RF will mean larger APS-C bodies and I don't think Canon wants that. With smaller FF bodies like RP selling for under $1000 and lenses like Canon RF 24-105mm f/4-7.1, it is clear that Canon wants to bring more and more users to FF. The primary target for Canon APS-C mirrorless in my opinion would continue to be those wanting very small bodies and lenses like the current EOS-M cameras. The only area where an APS-C RF body makes sense is a 7DII class APS-C body for use with professional f2.8 zooms and long tele lenses. Other than than I don't think there is much of a market for larger RF APS-C bodies with RF lenses.
I agree I think that Canon will keep the RF for full frame with an entry level camera with a much lower price, they will need a range of cameras around the M50 to replace the lower end DSLR's as the view finder is important to a lot of amateur photographers.
curious80 wrote:
I know I am in a minority here, but personally I don't see Canon abandoning EOS-M mount in favor of APS-C RF bodies. RF mount diameter is large enough that it will make it impossible to create small bodies like M200. .
Impossible, huh? That' is an awfully strong word.
I think you are underestimating both the flexibility of the RF mount and the intelligence of the engineers that work at Canon.
Regardless, splitting up the mirrorless line into two overlapping lens and camera systems is in nobody's best interest. Not consumers' and not Canon's. Canon knows this and they've likely put the M system on life support for an EOL in the not-so-distant future.
Meanwhile, be on the lookout for some of those small RF bodies that you claim are impossible.
