Opinion: Canon is causing its own problems with the RF mount

Michael Clark

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Apr 5, 2016
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Huh. Sony E-mount is narrower than Canon EF-M mount (46.1mm vs. 46.5mm). If the Sony E-mount cameras can take full-frame FE lenses why can't EF-M bodies? Also, Sony users are complaining about vignetting and problems with wide-angle lenses with E-mount. Sony could have avoided that problem by using Konica-Minolta's wider A-mount (49.7mm diameter), which was designed for 35mm full-frame, unlike the E-mount which was designed for NEX-style compact ILCs. So I can also argue that Sony painted themselves into a corner by using a lens mount designed for small cameras and shoehorning full-frame lenses for it. Look at the front of any Sony E-mount MILC without a lens and you can readily see that the full-frame sensor corners don't even clear the lens mount.


Exactly this. I disagree that Canon should have used the "M" mount for this FF mirrorless, because they would have painted themselves in the same corner as Sony. Moving forward, both Canon and Nikon will be able to take advantage of the larger diameter RF and Z mounts respectively for their mirrorless systems, while Sony will remain constrained with the E-mount, due to its design being meant for crop sensor cameras; not full frame.

I do agree that there will be consumer confusion with Canon having four different lens systems, and they need to work quickly to correct this. As an example, Nikon terminated the "Nikon 1" just before the Z System went on sale. Canon's M system has been arguably more successful, but I still wonder whether the long-term plan is to eventually phase out the M system in favor of the RF system?


Your photo doesn't help because it is shot at an angle, and, in any case, my point was the EF-M mount can take an FF sensor if the smaller E-Mount can. Also, the vignetting & wide-angle corner problems caused by the E-Mount is well-known.

View attachment 180124

Actually, the diagonal of a FF 36x24mm sensor is 43.5mm, so a FF sensor will *just* fit inside a 46.1mm throat diameter if you are properly aligned with the camera.
 
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3kramd5

EOS R6
Mar 2, 2012
3,084
405
it wouldn't even surprise me if the final choice wasn't made until the very last minute.

That would surprise me, significantly.

Hardware requirements are written early on. There were almost certainly trade studies, but the interface definition was probably approved and locked at least 2 years ago.

I guess by definition every decision is made at the last minute, but in this context, I can’t agree: that’s not how hardware development works.
 
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Michael Clark

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Apr 5, 2016
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Respectfully, perhaps you should consider the difference in aspect ratio in calculation, too. If I'm right, Canon APS-C sensor is 22.2(w)x14.8(h) mm and Super 35 is 24.6(w)x13.8(h) mm, that is, Super 35 sensor is a bit larger in width. Therefore APS-C image circle may not fully cover the Super 35 sensor, unless M lenses are built with larger image circle, which is quite likely. However, lens makers don't publish the image circle info so we won't be sure about that. Since Super 35mm is slightly larger than APS-C, in principle, using an APS-C lens while shooting in Super 35mm mode does not seem to be practical, without further tweaks.


I would imagine the wider focal lengths of current EF-M lenses would struggle. The EF-M 11-22mm for example, suffers up to -3 stops of light in the corners wide open at 11mm. Normal and short/mid telephoto lenses don't seem prone to the same amount of vignetting, so it's possible that most of the EF-M glass would perform well enough. Although Canon would almost certainly create a higher quality line of lenses for an EF-M super35 video platform if they pursued that route, since a dedicated video camera would likely be much higher-end in terms of electronic components than standard EOS M stills cameras (hence demanding more proprietary lenses for video work). Probably similar to what they did with the tilt-shift lenses for the EF line; only EF-M video lenses wouldn't just have a larger image circle, they would also likely include a t-stop ring as well as a separate textured focus ring.

Not to scale. If the diagonal measurements are the same, the image circle size needed is the same. Any more questions?

20180906ss1.png
 
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Michael Clark

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We should also consider that Canon may believe the 'problems' are minor and/or irrelevant.

Anecdotally, the use of EF lenses on APS-C bodies prior to a FF upgrade certainly occurs. There are examples on this forum, myself included. But is that typical/common? I know I'm far from typical – I had the 70-200/2.8L IS II, the 85/1.2L II, the 100-400L, and the 24-105/4L IS with the 7D, prior to getting the 5DII.

I wonder how many Canon APS-C owners upgrade to FF, how many have EF lenses when they do, and how many of those were lower IQ lenses that were replaced L lenses after the upgrade. But...whereas I can only wonder, Canon has the data. In light of those data, there maybe no real problem from their perspective.

I was using an EF 70-200mm f/2.8 L IS II on a 50D before got my first FF (5D Mark II) about a year after I bought the 70-200/2.8. I bought the kit that included the EF 24-105mm f/4 L IS with the 5DII because the 70-200/2.8 L IS II had sold me on 'L' glass.

The only other FF EF lenses I owned at the time were an EF 50mm f/1.8 II and an ancient EF 35-80mm f/4-5.6 that came with my Rebel II (film camera). I was using a Tamron SP 17-50mm f/2.8 Di II and an EF-S 55-250 plus the 50/1.8 on the 50D (both already owned when the 50D was purchased to replace a Rebel XTi) until I bought the 70-200/2.8 II. The EF mount Sigma 70-300mm f/4-5.6, bought in the early '90s) that I used with the film camera did not work with EOS digital bodies.

Oh, and an EF 28-135mm f/3.5-5.6 that I've never really used. It came with the 50D (I needed the camera on very short notice and the only one I could find locally at the time was the kit). I tried to like the 28-135, but it was too slow and too narrow for APS-C. By the time I bought my first FF, I was already addicted to constant aperture zooms.
 

Michael Clark

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Apr 5, 2016
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Pleased to be reading this thread as I have been contemplating the same topics over the weekend since the details leaked about the new EOS R mount. In particular I want to move to EVF - mirrorless bodies but I am trying to work out a plan to replace my current FF (6D) plus APSC (7DII) bodies. As suggested as a possibility in the Canon news article my first thought was that the future will involve a high resolution mirrorless body which I can use in either a FF or cropped mode. I think it is likely that a high resolution RF body will be Canon's next release.

I also agree that I see the attraction of the M lineup as keeping it small and light. I had wondered which way Canon would go with the FF mirrorless but now knowing the RF lens lineup "smaller and lighter" is definitely not the case, Canon instead offering faster lenses.

I read the observations raised in the Canon news article about starting off in an M world and not being able to migrate to FF whilst continuing to use ones existing lenses. However I am not sure how large a sector this is of the customer base. For example users who want to stay small could just stick with the M lineup in view of the impressive performance of modern APSC sensors. Users like me ( I have the EOS M and EFM 22) who want a body which is easy to drop in a pocket will have one M body and limited lenses as an add on to their kit. For users who want to migrate to a FF system then the invested value in a few EFM lenses is not great anyway compared to the cost of purchasing a FF body and FF EF or RF lenses.

My question though is in response to your statement "there wont be an APSC sensor RF body". I agree that Canon could very well decide to offer just a high resolution RF body instead. However is there any technical reason why there could not be an APSC sensor RF body which could be used with RF lenses or EF lenses plus adaptor?

From a business standpoint, the problem with that scenario is that there's nothing to keep the EF-M user from going to Nikon, Sony, Pentax, or (soon) Panasonic rather than sticking with Canon for the FF body. Even one or two (often soon outgrown) lenses is often enough to keep someone upgrading from APS-C to FF in the same ecosystem.
 
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fullstop

EOS R
Apr 23, 2018
1,088
153
Canon decided that two optimally chosen lens mounts as rock-solid foundation for each of their mirrorfree systems - APS-C and FF - are top priority.

EOS M / EF-M has been designed as a *limited system* offering decent IQ in a very compact package at very affordable prices. we could not use EF-M lenses on other Canon cameras and it was no problem. And we can still use all EF and EF-S lenses on EOS M system, but we can not use RF lenses on it. So what!

we also cannot use wheels and tires of any car maker's big pickup truck on the same car maker's smallest compact car. Nor vice versa. No problem, we accept technical facts and will not rant at the car maker about "wheel and tire incompatibility between different car categories". and folks happy with a compact car from that makers range are still very likely to consider that make first, when looking for a pick-up truck. although wheels and tires do not offer an "upgrade path".
 

moreorless

EOS RP
Jun 18, 2011
778
2
In a few years EF-M and EF-S will be on lifesupport. As big as canon are, they still need to focus on that one mount. EF will have a drawn out death depending on how quickly people migrate to RF, I'd say it will take about a decade and then canon will tell us that there will be no more development of EF mount products. Any lenses released in that timeframe will be designed with the RF adapter in mind though.
Unless sensor manufacturing costs go down, I would expect the future to hold a couple of APS-C bodies. Also, it seems to me that the 7D line has been popular enough that a mirrorless equivalent could be justified.

One thing to consider though is that EF-M and EF-S don't really take much development do they? I mean we've seen a few EF-M lenses released recently as the system is young but the kind of user its targeting doesn't tend to demand specialist lenses. Canon could very well carry on with the current lens lineup for an extended period.

Maybe you could argue that the lack of an upgrade path isn't such an issue as it is on DSLRs? people buying EF lenses to use on EF-S cameras are I'd guess mlore likely to be xD or 7D shooters and arguably no equivalent exists on EF-M.
 

Michael Clark

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Apr 5, 2016
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Let's face it: APS-C was invented in a time that full frame sensors were very expensive. Now that that problem has been solved, who needs APS-C?

Hobbyists and enthusiasts that want a 300mm f/2.8 angle of view and lens speed for a 200mm f/2.8 price on a camera that can shoot 10+ fps and do Servo AF between each frame.

Pure speculation: perhaps the new 7D could be the pro mirrorless 5 series we all assume is coming, but with a crop mode that boosts frame rate to 12.

Maybe there will be a 50 MP FF RF mount camera that will have an option to shoot in crop mode with a faster frame rate than when using the full 50 MP sensor, but Canon (and most everyone else) appears to still be a long way from doing sensor based Servo tracking at those kinds of frame rates. With some lenses the Sony α9 slows from 20 fps to 5 fps when AF tracking between each frame is switched on.
 

Michael Clark

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Apr 5, 2016
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"FF EF-M" wasn't possible due to the diameter not accommodating a FF sensor from my understanding. Mounting FF lenses on crop (EF-M) wouldn't vignette.

Sure they would if the lens' rear element is larger than the smaller (by 10mm) throat diameter of the EF-M camera. The flange on the camera would be directly behind the outer edge of the lens' rear element.

Cut the crap.

Pentax PK mount flange mount distance is 45.46mm, 1.46mm larger than EF (44mm) and there are many adapters out there, some with onboard electronics for compatibility with newer lenses. I use a "dumb" one with a PK 50mm f/1.2.

It's the 10mm larger throat diameter that is the main issue, not the 2mm difference in registration. The camera's flange ring would be 5mm inside the adapter's flange ring on the other side.


so funny. all the drama, whrn everything is totally logical and clear.

Canon goes from 2 mounts in the mirrorslapper past to 2 mounts in the mirrorfree future. they do not compromise on lens mounts. Not in 1987, not today. one thing i really like about them.

1 perfectly chosen mount for compact APS-C cameras and a limited selection of decent and compact lenses. And 1 optimally chosen mount for great FF cameras and a full lens lineup to match. No problem whatsoever. and smooth transition from EF to RF.

Nikon looks set to go with only 1 mount for both FF and APS-C. thats one of the reasons they went with only 16mm FFD - to allow for "slim"
APS-C cameras as well.

but back to Canon: so we cant use EF- M crop lenses on full frame R cameras? OMG! who cares, it is a stupid idea to start with. dont tell me using a crop lens on FF sensor "in crop mode" yields better IQ than just doing the crop in post.

and as for RF to EF- M adapter, why should that not be possible? After all renown german maker Novoflex makes precise 2.5mm adapters for use of Nikon F lenses(46.5mm FFD) on Canon EF mount (44mm). they even manage to fit mechanical aperture control on the little contraption. so why should a canon RF to Canon EF-M 2mm adapter with wiring through and possibly a chip/firmware in it for protocol translation not be possible? although it also makes rather limited sense to stick a 28-70/2.0 on an EOS M50.

most of the adapter and cross-use angst postings are from folks worrying about residual/second-hand value of their (soon) legacy EF lenses. nothing else.

Canon is doing the right thing here and they do it boldly. wish they would be as bold with their mirrorfree FF cameras!

The EF mount throat diameter is 54mm, not 44mm.


Let's not forget that the RF mount is much wider than the EF-M mount and that part of the RF bayonet sits inside the RF mount. So if the RF bayonet does not fit inside the EF-M mount (which it probably doesn't) , it may very well be that even without an adapter, it's not possible to position an RF lens close enough to a EF-M mount.

BINGO! We have a winner!
 

Michael Clark

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Apr 5, 2016
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I think forum posters are the largest percentage, by a mile. Pros will use what does the job best, sometimes that's an adaptor.

Pros are mostly anti cross-platform adapters, where things such as AF and are reverse engineered. They don't have the same issue with extenders or macro extension rings where the protocols on both flanges are the same.
 

padam

EOS R
Aug 26, 2015
1,261
921
Can anybody comment on why the mount on the back of the RF lenses (where the black outer parts meets silver) look the way the do? They don't need to look like that if the contact to the RF mount is placed a bit further back. Here is what I mean:

Canon-EOS-R-grip.jpeg


Maybe I'm totally wrong, but I think that it is because they are still developing higher end cameras, with a hybrid switchable mount that can accept both RF and EF lenses natively.
 

illadvisedhammer

buggin out
CR Pro
Aug 19, 2015
27
11
Here in sample-size-of-one land, my response to the imminent obsoleting of my beloved 80D was to .. double down on EF-S and pick up an inexpensive used Sigma 50-100 1.8 for indoor sports and portraits. It's a lot cheaper than trying to match with FF. Also sold the 6d in hopes of 6D II prices falling over the next few months. I love the low light IQ of the 6d and the DOF / perspective with cheap primes that I already had in EF, but the focusing was clearly pokey compared to the 80D. My main passion is insect macro, which like birds usually benefits from high density crop. I am fine with having EF-M stick to compact, right now the M6 has good focus and great image quality in decent light, but focus becomes unusable in low light that barely taxes the 80D or even the 6D. I could see buying a crop body in RF mount, which seems like the best way to upgrade the 7DIII or IV, if and only if it had my own weird idiosyncratic features tailored to macro shooting; focus bracketing, in-camera focus stacking, an AF MPE-65 update to take advantage of those features, and an intervalometer that goes down to 4 or 5 per second instead of 1 per second, to take better time lapse of eggs and chrysalises hatching. Really I don't feel obsoleted because the 80D could be my last camera and I'd never run out of challenges.
 

Michael Clark

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Apr 5, 2016
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Here in sample-size-of-one land, my response to the imminent obsoleting of my beloved 80D was to .. double down on EF-S and pick up an inexpensive used Sigma 50-100 1.8 for indoor sports and portraits. It's a lot cheaper than trying to match with FF. Also sold the 6d in hopes of 6D II prices falling over the next few months. I love the low light IQ of the 6d and the DOF / perspective with cheap primes that I already had in EF, but the focusing was clearly pokey compared to the 80D. My main passion is insect macro, which like birds usually benefits from high density crop. I am fine with having EF-M stick to compact, right now the M6 has good focus and great image quality in decent light, but focus becomes unusable in low light that barely taxes the 80D or even the 6D. I could see buying a crop body in RF mount, which seems like the best way to upgrade the 7DIII or IV, if and only if it had my own weird idiosyncratic features tailored to macro shooting; focus bracketing, in-camera focus stacking, an AF MPE-65 update to take advantage of those features, and an intervalometer that goes down to 4 or 5 per second instead of 1 per second, to take better time lapse of eggs and chrysalises hatching. Really I don't feel obsoleted because the 80D could be my last camera and I'd never run out of challenges.

How could there be an AF MP-E 65mm? There's only a single focus distance available for each magnification. For any specific magnification, the MFD (minimum focus distance) is also the maximum focus distance.

To change the focus distance one must also change the magnification. To change the magnification one must also change the focus distance. There are no independent movements for focus distance and for magnification. With the MP-E 65mm they are one and the same thing.
 

drmikeinpdx

Celebrating 20 years of model photography!
This is all very confusing to someone like me who was quite happy with my 5D series bodies and EF lenses for pro use, augmented by small EF-S bodies as travel and walking around cameras.

I see very few practical advantages in the mirrorless systems, beyond the new & cool factor, so I won't be switching for a very long time.

I'm also concerned now that Canon will be diverting resources away from the EF and EF-s platforms that have worked well for me.
 

koenkooi

EOS 5D Mark IV
CR Pro
Feb 25, 2015
1,919
1,860
How could there be an AF MP-E 65mm? There's only a single focus distance available for each magnification. For any specific magnification, the MFD (minimum focus distance) is also the maximum focus distance.

To change the focus distance one must also change the magnification. To change the magnification one must also change the focus distance. There are no independent movements for focus distance and for magnification. With the MP-E 65mm they are one and the same thing.

Forget AF, how about a MP-TE 65mm with tilt? I briefly owned a TS-E 90mm for macro work and loved the shift, but the 0.3x max magnification made it impractical for me to use.
 

illadvisedhammer

buggin out
CR Pro
Aug 19, 2015
27
11
How could there be an AF MP-E 65mm? There's only a single focus distance available for each magnification. For any specific magnification, the MFD (minimum focus distance) is also the maximum focus distance.

To change the focus distance one must also change the magnification. To change the magnification one must also change the focus distance. There are no independent movements for focus distance and for magnification. With the MP-E 65mm they are one and the same thing.

You're right, although once I've picked a distance / composition either moving the camera or changing the magnification on the lens slightly is for focus rather than magnification. I probably shouldn't have mentioned the MPE, but an autofocus macro that goes down to 3X or 4X would allow for focus bracketing or stacking in camera.
 

Michael Clark

Now we see through a glass, darkly...
Apr 5, 2016
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You're right, although once I've picked a distance / composition either moving the camera or changing the magnification on the lens slightly is for focus rather than magnification. I probably shouldn't have mentioned the MPE, but an autofocus macro that goes down to 3X or 4X would allow for focus bracketing or stacking in camera.

With anything greater than 1:1, the MFD and maximum focus distance begin to converge fairly quickly. Very few macro photographers shooting at greater than 1:1 use AF at all. That's what a focusing rail is for. So there's no real demand for an AF lens in that segment.

It's just like the vast majority of Cinema camera operators use manual focus, so very expensive Cinema lenses don't even offer AF.
 
Sep 12, 2018
1
0
Newbie here, but wouldn't an adapter with optics inside of it be able to change the focal distance of the lens, therefore a thicker adapter could be made to adapt an RF lens to the EF-M mount? Essentially it would change the flange distance of the RF lens to one that could be longer, but still concentrate light on the APS-C sensor of the EF-M sensor? It's been quite some time since I've done optics, but I think that is possible, right? If so, it would cost a few hundred dollars, which would be offputting for the casual photographer that the M series is aimed at, but for the Pros and Prosumer Amateurs out there, it would a great way to have a second body.