Richard over at Canon News has written an opinion piece about the new Canon RF mount and what it means for the Canon ecosystem. He feels, as others do, that the EOS M system and EF-M mount are surrounded with some uncertainty.
From Canon News:
Canon this September 5th is releasing the RF mount for full frame mirrorless. This mount by all reports is 54mm in diameter for the inner throat diameter and 20mm in depth. While this mount by itself sounds good, it has long term negative ramifications on the EOS system over time, that has us surprised they are doing this unless there are tectonic shifts in direction throughout Canon's lineup.
The problem with this new mount, is not what you can do with it, but what you can't do with it. Canon in 2012 created a new mount for APS-C mirrorless called the EF-M mount. It has a 46mm throat diameter and a 18mm registration distance. Because of the difference in between the two mount registration distances (the distance between the sensor and the mount flange) of only 2mm, there will never be an EF-M camera to RF lens adapter, nor will there ever be a RF APS-C camera that can use EF-M lenses with an adapter. Read the full article
As excited as we are about the Canon EOS R and RF lenses, we do wonder what's in store for the EOS M system going forward. We are getting that fast prime in the EF-M lineup with the EF-M 32mm f/1.4 STM, but we can't help but hope there is more coming down the pipeline for the Canon EOS M system.
I think it's possible that Canon reserve the EF-M mount for the very compact and small mirrorless system. If this is true, future release of EF-M lens should be compact and small.
Have a nice day.
Someone won't be able to put 28-70/2 non-IS on M50?
Is it really a problem for Canon?
The RF mount certainly causes some issues with Canon going forward, even if they dump the EF-M mount.
Life would have been easy if they a) used the EF-M mount for full frame b) increased the registration distance and decreased the throat diameter a bit off the RF mount to allow for an adapter. maybe they ditch the EF-M all together, it's certainly a possibility. That would be hard to swallow now that they are starting to gain momentum on the mount.
While that doesn't impact the system now, going forward if they decide to be competitive in the APS-C mirrorless they are going to have to come out with a 7D-like mirrorless, and where does that sit and what mount does it use is a problem no matter what they choose.
Why would you want a EF-M lens that only fills up an APS-C area on a full frame mount? EF-S also can't be used on EF and nobody batted an eye yet.
The new mount tho, lets you use EF, EF-S and probably also FD soon.
I'm not remotely concerned about not being able to put an EF-M lens on an RF body, but it sounds like they're suggesting RF lenses won't be adaptable to EF-M bodies.
If you really cannot adapt an RF lens to an EF-M body, that is indeed unfortunate. While physically I can imagine an adapter could be made to go from a 46mm wide, 18mm deep mount to a lens designed for a 54mm wide, 20mm deep mount... jamming the wiring in probably means thinner/weaker metal somewhere with so few millimeters to spare. Plus, some lenses with protruding rear components... eesh yeah it becomes a mess.
I see the confusion with the writing here. We won't see RF lenses adapted for EF-M. This may create a problem for some shooters that would want an EOS M as a backup to an EOS R, you're going to have to have 2 sets of lenses. There are a lot of people that use a 7D2 as a backup to a 5D and EOS-1 series camera and can purchase one set of lenses to fit the needs of both.
But: i'm not so sure how successfull R lenses will be. The beauty of adapting EF lenses is that it's electronics only, compared to Nikons numerous F-flavors with mechanics and all that. I've been shooting Canon crop bodys for 12 years now and never considered FF because most of the time i focus to something off center and a 6D has a narrow AF point spread and a 5D is too expensive for this amateur. But this R sounds very interesting to me because slow fps but a large AF area is just what i need. But i would not consider buying a R lense like the 24-105 if i can get the more flexible EF version for a similar price or even lower when bought used.
So far the 28-70/2 seems to be the only real not-possible-in-EF lens and this beast will be way to expensive for me.
Interessting times. Can't wait for the official anouncement on wednesday about all R features and prices.
1.) There isn't a single lens on the EF-M mount I would want to adapt on a full-frame sensor and then crop in. It's no secret that the 22mm is a great little lens, but beyond that, only the 11-22mm is really anything special. I have the M50 for size and convenience. It's a somewhat pocketable 80D and it's what I use it as exclusively. I pack a full roller bag when I travel for work and can slip the M50 with the 22mm almost anywhere. The M lineup of lenses...or lack there of, have all shared a focus on size over performance. It's honestly what I like about it. Sure, faster lenses would be nice, but with more light comes more heft. It's fine if they wish to offer larger, faster lenses...but it doesn't appear that Canon is considering that with zooms any time soon.
2.) If these rumors hold true, Canon will now be selling lenses for four different camera mounts - EF-S, EF-M, EF, and RF. The only true discrepancy in this lineup is that the two mirrorless camera mounts won't play together...I'm sure Canon has looked at its lens sales and understands it's not really missing out on very many cross platform support. As mentioned above, Canon full-frame was never able to work with EF-S lenses. But, you have now lost the upgrade path of buying a crop sensor body and investing in full-frame lenses to upgrade over time. You can no longer do this in the mirrorless ecosystem
What does this mean for the future of the EOS-M mount? Like others have said, I really hope they maintain a priority of keeping the M system as compact as possible. God knows that the RF 28-70 and 50mm f/1.2 won't be. If you want a light, consumer/prosumer camera to take on vacation, shoot video or vlog with, the EOS-M series is your ticket. If you're looking for a professional mirrorless system, the RF cameras is your choice.
I admit, this creates concerns for the future of the M-mount. But I'm extremely happy they didn't try to force the mount to work with full-frame and make sacrifices in capabilities, performance and the future overall.
I think we all know the answer is that there won't be an APS-C sensor RF body, and those wanting to use lenses on both an M series and an R series camera are stuck with EF lenses and adaptors on both bodies.
Right!
But then you have a weathersealed mag alloy nice camera body using non-weathersealed consumer lenses EF-M or older EF L lenses.
Meanwhile in Sony land, you can interchange and use from a catalog of FE and E mount lenses seamlessly. Sony keeps you in their ecosystem, Canon may force you to wholesale switch.
That isn't the issue at all. It's the reverse.
Think about at the moment. You get an 80D and you buy some lenses. Let's look at someone who bought an EF-S 18-55, an EF-S 10-18, a 50mm f/1.4 and a 70-300 IS non-L zoom. Maybe your later lens choices were in part driven by knowing the lenses are future-proof if you decide to switch to FF.
Part of the incentive in upgrading from the 80D to full frame is that at least some of your lenses can continue to be used.
Now, if Canon had for example kept to the EF-M mount for full frame, in the future we could have the same situation, low cost 50mm f/1.8 or 1.4 EF-M lenses and a low cost 70-300 that would work with the EF-M but would also provide a full-frame image circle for when you upgraded to a FF camera.
Instead, you're stuck with APS-C only EF-M lenses, and the incentive to upgrade is far less. Suddenly the entry cost to FF is prohibitive.
This doens't affect Nikon because they have no APS-C mirrorless, and it doesn't affect Sony because they share the same mount.
Now, the advantages of the new mount are almost certainly worth the pain, but it is now going to be difficult to justify recommending EOS-M cameras to anyone because they will be stuck in an APS-C forever ecosystem.
It's a valid point about EF-M not mounting to RF (you'd want to do that if the R has crop mode functionality, like many other non-canon cameras), but that decision was made a long time ago with the EF-M diameter being too small to fit a FF sensor.
The real problem for Canon is what they tell pros. Clearly they want pros moving to the RF mount with the L lenses released, but pros are the largest percentage of the anti-adapter crowd. How is Canon going to hold them over until RF matures and offers a competing line-up to EF? Will the 5DV and 1DX be mirrorless with EF mount?
The short answer is that if the EF-M mount was capable of using RF lenses with an adaptor then there would have been precisely zero benefit in using the RF mount over using FF EF-M mount to begin with. Ie it may be possible assuming you're a genius with enginering to physically adapt the lenses assuming the rear elements fit, but it'd vignette like crazy.
the mount depth with the lugs to hold the lens onto the mount requires a further depth of at least 3mm. you also have the electronic interconnects on both sides (mount and lens side). you also need the pin, lever and knob to remove the lens from the mount adapter.
then you have the fact that the mount is a 10mm greater diameter, and if a lens sits inside of the mount any, such as what the 35mm 1.8 RF does, it would not physically be able to mount on the adapter at all.
for a reverse adapter (RF body and EF-M lens), each EF-M lens is 61mm, it could not sit "inside" an RF mount adapter to get 2mm closer to the sensor.
I think forum posters are the largest percentage, by a mile. Pros will use what does the job best, sometimes that's an adaptor.