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Canon is causing its own problems with the RF mount

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.

This is a problem.

Sony, by all reports is launching a new APS-C mirrorless high-end camera and augmenting further its lineup of APS-C mirrorless cameras. By nature of using the same mount for both APS-C and full frame, these camera bodies have the luxury of using either APS-C lenses or new modern FE full frame lenses. Users can choose which lenses by purchase from a wide degree of options from both FE full frame and E mount APS-C lenses to create their kit. They can use small wide-angle lenses designed for APS-C and use mirrorless full frame lenses interchangeably.

If Canon continues to grow the EF-M lineup, no EF-M camera body will be able to use the RF lens catalog. While at first glance, right now this isn't much of a problem because there's only four RF lenses, however, the 50mm 1.2L RF lens shows that Canon is looking to create RF lenses that compete or even, possibly, replace the EF lens catalog. Unlike Sony, Canon users will never can take advantage of new RF lenses on their EF-M camera bodies.

Right now, with the EOS-M5 technically at the 80D level of functionality this really isn't as much a problem, but what happens when Canon creates a 7D class APS-C camera body. Then what mount is best suited for it? With only professional lenses being created on the RF mount, it would naturally make sense for a 7D mirrorless to support the RF mount. However, then the 7D cannot take advantage of any excellent small lenses from the EF-M lineup such as the 11-22, 22mm or the 32mm 1.4 being released on September 5th. Unless Canon delivers APS-C wide angle lenses for the RF mount, then it's impossible for a 7D RF mount mirrorless camera to ever support wide angle field of view without resorting to EF-S lenses that, by that time may becoming obsolete and are certainly not optimized for short registration distance mirrorless camera bodies. If you make a high end 7D EF-M mount camera, then it will never use the new mirrorless optics, and will be forced to use EF lens optics that may become obsolete over time as Canon focuses on the RF mount over the EF mount. You simply couldn’t use any of the optimized L lenses that were created for the RF mount.

This further complicates the upgrade path from basic entry level mirrorless into more serious mirrorless cameras. I'm sure many that would upgrade from the M5 camera level would still like to use the 11-22 and 22mm mirrorless lenses in crop mode on a RF camera body until Canon releases UWA lenses for that mount, or perhaps, until they can afford to buy such lenses. If Canon releases a 7D RF mount camera body, there would be no migration path from the M5 or lower APS-C entry level mirrorless cameras without starting the system over again from scratch. Right now, we can't see any way of migrating up through Canon's mirrorless APS-C lineup if a 7D styled camera body comes out for mirrorless. This is a problem because if you must start again from scratch, you have no loyalty to stay with Canon and can just as easily move to any other system, that perhaps is better suited for supporting both APS-C and full frame.

As a matter of fact, this is as much of a problem as it makes us wonder if Canon is looking at making RF APS-C lenses to future support APS-C cameras on the RF mount instead of the smaller EF-M mount and slowly phasing the EF-M, EF-S and EF mounts out of existence over time. However, even this has its own problems as with a larger RF mount it becomes impossible to make cameras as small as say for instance, the M100.

It could also be that Canon sees the need for 7D styled cameras disappearing with mirrorless and high-density sensors capable of over 10 fps on full frame, such as what the D850 can do right now for DSLR's. Maybe they full that all cameras outside of the basic entry level models will be full frame, and they have no plans to make a professional APS-C mirrorless camera to compete against the X-T3 and future Fuji cameras, and future Sony A6000 or A7000 series cameras. Perhaps they see a future eroding of APS-C in general, and simply feel that over time the only mount left standing will be the RF mount. However, this line of thinking leaves an entire segment of the market that Canon will not or cannot take create products for.

We would have loved to have been in the meetings when this was all being hashed out at Canon, and we hope that they clarify their direction on what they are going to do with APS-C and most importantly professional grade cameras and APS-C.

Addendum

It seems like this article has caused quite the furor across the internet.

This wasn't an article saying that Canon made a huge mistake and that they are stupid. I'm sure there was a massive amount of discussions in Canon Inc over the potential solutions to this problem, and it wouldn't even surprise me if the final choice wasn't made until the very last minute. This article was written as my opinion, especially as someone that actively uses the EF-M system and loves its portability and versatility all packed into the small size of the EOS-M system. However, like many that have purchased an M5 (or an M6), the lure of a better more feature rich, better sealed camera body is something that at least I wish for. I would also still wish to use existing mirrorless lenses. In a perfect world I would also want to use mirrorless optimized RF lenses as well. This should come as no surprise to anyone. It's not a unique request, and it's one that Sony, for instance, handles gracefully.

I personally feel that Canon over time needs to phase out the EF-M, EF-S, and EF lineup and concentrate on RF lenses for both full frame and crop APS-C. Canon's main competitor in this field, Sony, allows for seamless utilization across APS-C and full frame cameras for all their lenses from their lowly APS-C consumer lenses to their super GM series lenses. What I am identifying - is that this is now missing from Canon's lineup the way it stands today. It’s a bit of a mess, and it’s one of Canon’s own decision making, no one else.

I hope this article continues to create some debate, and in the days ahead after Canon releases the EOS R and the related RF mount, that some questions are presented to Canon asking to clarify the direction of the EF-M, EF-S and EF systems.

No, the sky is not falling but it's cloudy with a chance of rain.

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