The diameters of EFM and RF mounts

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake. They must have thought that the mount was good enough against M43 kingdoms or Sony E mount. Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort. Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors. Now RF appears to want to support both as well. At this moment, I think Canon had made another mistake when they released RF. The mount looks too big to be shared with APS C bodies since they have to give up small form factor. Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Would Canon really have chosen 54mm if they had not had EFM?

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M, I think, however, Canon would not be able to avoid using RF for APSC bodies in the end. It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

What do you think? Which of the following would be the best solution?

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake. They must have thought that the mount was good enough against M43 kingdoms or Sony E mount. Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort. Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors. Now RF appears to want to support both as well. At this moment, I think Canon had made another mistake when they released RF. The mount looks too big to be shared with APS C bodies since they have to give up small form factor. Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Would Canon really have chosen 54mm if they had not had EFM?

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M, I think, however, Canon would not be able to avoid using RF for APSC bodies in the end. It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

What do you think? Which of the following would be the best solution?

The RF mount is the same 54 diameter as the diameter as the EF/EF-S mount which has been used for years on both full frame and APS-C cameras.  Canon did not increase the diameter of their mount when coming up with the RF mount.

Nikon increased mount diameter to 55 mm for the Z mount from the F mount's 44 mm.  This mount has a slightly larger diameter that the Canon RF mount.  As you pointed out, Nikon already uses the Z mount for both full frame and APS-C.

jtstanco wrote:

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake. They must have thought that the mount was good enough against M43 kingdoms or Sony E mount. Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort. Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors. Now RF appears to want to support both as well. At this moment, I think Canon had made another mistake when they released RF. The mount looks too big to be shared with APS C bodies since they have to give up small form factor. Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Would Canon really have chosen 54mm if they had not had EFM?

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M, I think, however, Canon would not be able to avoid using RF for APSC bodies in the end. It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

What do you think? Which of the following would be the best solution?

The RF mount is the same 54 diameter as the diameter as the EF/EF-S mount which has been used for years on both full frame and APS-C cameras. Canon did not increase the diameter of their mount when coming up with the RF mount.

So true. I missed the point. Thank you for your reminder. On the other hand, the mirrorless systems can reduce the body size thanks to the short flange distance, while there was no big difference between DSLR FF and Cropped bodies in terms of their sizes. The compactness was one of the main features of M4/3 mirrorless system and what Sony is still pursuing, I believe.

Nikon increased mount diameter to 55 mm for the Z mount from the F mount's 44 mm. This mount has a slightly larger diameter that the Canon RF mount. As you pointed out, Nikon already uses the Z mount for both full frame and APS-C.

medium format sized ????? Omg

How large is that mount ?

MyM6II wrote:

medium format sized ????? Omg

How large is that mount ?

Oh, my bad. sorry for the confusion. I believe you know what I really mean.

lumenite wrote:

MyM6II wrote:

medium format sized ????? Omg

How large is that mount ?

Oh, my bad. sorry for the confusion. I believe you know what I really mean.

👍😀

The best solution is to make somehow 2mm M to R adapter. Or possibility to change m mounts  bayonete to R... 😃

The EF-M mount would have worked just fine. (IMHO)

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake.

Mistake? You mis-read Asian corporate culture methinks. A smaller M-Mount was part of their plan all along. They think in the Loooong term.

Myself, I can certainly see Canon's logic. Why sell just one lens line when you can sell two! Or threee! It's brilliant!

They must have thought that the mount was good enough against M43 kingdoms or Sony E mount.

Absolutely.

Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort.

This is exactly right. Plus it's been super-popular to boot!

Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

The RF mount much better accommodates Full Frame Mirrorless. It was a natural progression.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors.

Except Canon and Nikon now aren't locked into an inferior mount. They have that big wide throat to work with.

Now RF appears to want to support both as well.

So? It costs them next to nothing to develop a couple of cheapo RF-S lenses. As some have mentioned, they could even basically re-run a couple of EF-M designs with a new mount!

At this moment, I think Canon had made another mistake when they released RF.

Not me. I've been shooting with Canon RF for almost 2 years now, and it's magnificent.

The mount looks too big to be shared with APS C bodies since they have to give up small form factor.

Thus EOS-M! It was viable back with EF, and it's still viable with RF on the scene. I'm living proof! Vive le 'M!! Vive le 'M!! 

Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Again, it can be used for both FF and crop. Just like EF was. For minimal expenditure.

Would Canon really have chosen 54mm if they had not had EFM?

Certainly.  It allows for improved lens designs!

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M

Canon might (might!) give up on EOS-M, but we don't have to.

I think, however, Canon would not be able to avoid using RF for APSC bodies in the end.

Right. Why develop another APS-C mount when it's not needed.

It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

EOS-M is operating all in The Black for Canon. Even an M6 Mark III "firmware upgrade" would cost them next to nothing.

What do you think? Which of the following would be the best solution?

The best solution depends on what you're shooting, and how.  IMHO it's great to have a number of excellent choices...  Rather than the other way around.

R2

MyM6II wrote:

The EF-M mount would have worked just fine. (IMHO)

It has been working wonderfully even for me.

R2D2 wrote:

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake.

Mistake? You mis-read Asian corporate culture methinks. A smaller M-Mount was part of their plan all along. They think in the Loooong term.

It will turn out to be a mistake if Canon really ditches the mount any time soon, although it will have lasted longer than Nikon 1.

Myself, I can certainly see Canon's logic. Why sell just one lens line when you can sell two! Or threee! It's brilliant!

That's one of the things that I do not understand regarding Canon's strategy about APS-C system. Why do they not put more money to APS-C when they are still the number one in Camera industry? Just a little more lenses and bodies for APSC would have been great.

They must have thought that the mount was good enough against M43 kingdoms or Sony E mount.

Absolutely.

Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort.

This is exactly right. Plus it's been super-popular to boot!

Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

The RF mount much better accommodates Full Frame Mirrorless. It was a natural progression.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors.

Except Canon and Nikon now aren't locked into an inferior mount. They have that big wide throat to work with.

Now RF appears to want to support both as well.

So? It costs them next to nothing to develop a couple of cheapo RF-S lenses. As some have mentioned, they could even basically re-run a couple of EF-M designs with a new mount!

At this moment, I think Canon had made another mistake when they released RF.

Not me. I've been shooting with Canon RF for almost 2 years now, and it's magnificent.

The mount looks too big to be shared with APS C bodies since they have to give up small form factor.

Thus EOS-M! It was viable back with EF, and it's still viable with RF on the scene. I'm living proof! Vive le 'M!! Vive le 'M!!

Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Again, it can be used for both FF and crop. Just like EF was. For minimal expenditure.

Would Canon really have chosen 54mm if they had not had EFM?

Certainly. It allows for improved lens designs!

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M

Canon might (might!) give up on EOS-M, but we don't have to.

Yes. I won't give up until my things die since I do not know how to sell all of them and restart all things from the scratch.

I think, however, Canon would not be able to avoid using RF for APSC bodies in the end.

Right. Why develop another APS-C mount when it's not needed.

It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

EOS-M is operating all in The Black for Canon. Even an M6 Mark III "firmware upgrade" would cost them next to nothing.

What do you think? Which of the following would be the best solution?

The best solution depends on what you're shooting, and how. IMHO it's great to have a number of excellent choices... Rather than the other way around.

R2

Thank you for your interactive reaction!

lumenite wrote:

Myself, I can certainly see Canon's logic. Why sell just one lens line when you can sell two! Or threee! It's brilliant!

I certainly agree with that. Buying M6II I wasn't intending to upgrade to FF at all. I upgraded from 300D to 5D M III in the past and I don't see "one mount fits all" as a real value.

That's one of the things that I do not understand regarding Canon's strategy about APS-C system. Why do they not put more money to APS-C when they are still the number one in Camera industry? Just a little more lenses and bodies for APSC would have been great.

Here in Europe I don't see Canon as a market leader. I see more Sony/Nikon on display. Visiting some electronic store like Mediamarkt I always wonder why according to some reports Canon is the leader of photo equipment, it doesn't look so.

nnowak wrote:

R2D2 wrote:

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake.

Mistake? You mis-read Asian corporate culture methinks. A smaller M-Mount was part of their plan all along. They think in the Loooong term.

Yes, Japanese companies tend to take a very long term outlook, but there are clear mistakes in the design of the EF-M mount that suggest that Canon did not anticipate a future with professional level full frame mirrorless.

Even beside the size of the eos-M mount there's more evidence this is the real mistake of Canon.  Canon should have launched the R6 and R5 before at the same time as the launch A7III.  Even the R was significantly later launched as the A7III, and as the first model of the RF line this is clearly a product of a company not thinking forward enough.

Right now Canon is on par as it comes to sensor tech.  The big question is if Canon can follow Sony if it's doing a next round sensor upgrades.  Is the Canon tax we pay enough to finance new sensor fabs? Or will Canon lay back again leaving the owners of RF L glass without sensor upgrades?  Beware of doing "investments".  "Investments" might give ROI for the next 5 or even 3 years only if you love the best sensor tech.

Comparing the FE 50mm f/1.2 G-master to the RF 50mm f/1.2 L the bigger RF mount doesn't give an advantage for optical designs of lenses. I'm not sure if a bit better IBIS is enough to justify the size of the RF mount.  So I would argue the M mount probably isn't too small, I would rather argue the R mount was both too late to the show AND too big. With the RF mount you can't make a camera more compact than the A7C. With the FE mount you can. It's not only the weakness of the M mount (being too small for full frame)  forcing Canon to create the RF mount, it's also the weakness of the RF mount (being too big) to make truly compact cameras forcing Canon to sustain the M mount.

There's a lot of speculation of discontinuation of the M mount. At the end of the day the M50II and the M200 are at least available. Go try to by an A6100 or A6400.  It's nice when a mount is shared with full frame so we all should assume aps-c would last forever in the Sony world, however, if you can't buy it these kind of eternities won't bring you much.....

Making the mount just a couple millimeters larger would have allowed EF-M to fit a full frame sensor. If EF-M and RF flange distances were changed by only a couple millimeter, adapting RF lenses to M bodies would have been possible.

lumenite wrote:

R2D2 wrote:

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake.

Mistake? You mis-read Asian corporate culture methinks. A smaller M-Mount was part of their plan all along. They think in the Loooong term.

It will turn out to be a mistake if Canon really ditches the mount any time soon, although it will have lasted longer than Nikon 1.

The M occupies a niche that cannot, will not, (not in anyone's wildest dreams!) be filled by a crop RF body.  ...and to your point it is the diameter of the EF-M mount that actually guarantees this! 

Myself, I can certainly see Canon's logic. Why sell just one lens line when you can sell two! Or threee! It's brilliant!

That's one of the things that I do not understand regarding Canon's strategy about APS-C system. Why do they not put more money to APS-C when they are still the number one in Camera industry? Just a little more lenses and bodies for APSC would have been great.

Canon first and foremost protects their own higher level camera lines.  It's built into their corporate identity!

They must have thought that the mount was good enough against M43 kingdoms or Sony E mount.

Absolutely.

Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort.

This is exactly right. Plus it's been super-popular to boot!

Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

The RF mount much better accommodates Full Frame Mirrorless. It was a natural progression.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors.

Except Canon and Nikon now aren't locked into an inferior mount. They have that big wide throat to work with.

Now RF appears to want to support both as well.

So? It costs them next to nothing to develop a couple of cheapo RF-S lenses. As some have mentioned, they could even basically re-run a couple of EF-M designs with a new mount!

At this moment, I think Canon had made another mistake when they released RF.

Not me. I've been shooting with Canon RF for almost 2 years now, and it's magnificent.

The mount looks too big to be shared with APS C bodies since they have to give up small form factor.

Thus EOS-M! It was viable back with EF, and it's still viable with RF on the scene. I'm living proof! Vive le 'M!! Vive le 'M!!

Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Again, it can be used for both FF and crop. Just like EF was. For minimal expenditure.

Would Canon really have chosen 54mm if they had not had EFM?

Certainly. It allows for improved lens designs!

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M

Canon might (might!) give up on EOS-M, but we don't have to.

Yes. I won't give up until my things die

Me too!  Me too!   

since I do not know how to sell all of them and restart all things from the scratch.

I think, however, Canon would not be able to avoid using RF for APSC bodies in the end.

Right. Why develop another APS-C mount when it's not needed.

It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

EOS-M is operating all in The Black for Canon. Even an M6 Mark III "firmware upgrade" would cost them next to nothing.

What do you think? Which of the following would be the best solution?

The best solution depends on what you're shooting, and how. IMHO it's great to have a number of excellent choices... Rather than the other way around.

R2

Thank you for your interactive reaction!

Nothing like a little competition to spark discussion! 

R2

nnowak wrote:

R2D2 wrote:

lumenite wrote:

In my opinion, Canon's first decision as to the diameter of EFM mount was a mistake.

Mistake? You mis-read Asian corporate culture methinks. A smaller M-Mount was part of their plan all along. They think in the Loooong term.

Yes, Japanese companies tend to take a very long term outlook, but there are clear mistakes in the design of the EF-M mount that suggest that Canon did not anticipate a future with professional level full frame mirrorless. Making the mount just a couple millimeters larger would have allowed EF-M to fit a full frame sensor. If EF-M and RF flange distances were changed by only a couple millimeter, adapting RF lenses to M bodies would have been possible.

You're describing what would sound good to us, and not what would work best for Canon's bottom line.

Myself, I can certainly see Canon's logic. Why sell just one lens line when you can sell two! Or threee! It's brilliant!

Why sell three lens lines when you can sell a single lens line three times.

That's complete babble.  I've used my (same) EF 85mm f/1.8 on every body line so far.  I did not buy it threee times.

Having multiple lens lines is a lot more challenging when your sales volume gets cut in half over just three years.

Sales volume is determined by the products you make available.  Just ask Coke or Pepsi, or Tide for that matter.

They must have thought that the mount was good enough against M43 kingdoms or Sony E mount.

Absolutely.

Moreover they must have not been serious with mirrorless system at the moment since APS-C market has not been their main target. It seems certain that they just wanted to defend the market with the minimum effort.

This is exactly right. Plus it's been super-popular to boot!

It is still outsold by the EF mount.

And the EF mount is dead.

Finally they had to develop another mount, which is RF with 54mm diameter, while the diameter of EFM is 47mm.

The RF mount much better accommodates Full Frame Mirrorless. It was a natural progression.

Sony E mount is 47mm wide; Leica L, 51mm; Nikon Z 55mm. All of them support both full frame and APS-C sensors.

Except Canon and Nikon now aren't locked into an inferior mount. They have that big wide throat to work with.

It definitely makes it easier, but Sony seems to be coping just fine.

Sony was the first to "cook" their corners.  It's become ingrained in their design now.  Canon and Nikon now do the same, but to better effect (IMHO).

Now RF appears to want to support both as well.

So? It costs them next to nothing to develop a couple of cheapo RF-S lenses. As some have mentioned, they could even basically re-run a couple of EF-M designs with a new mount!

At this moment, I think Canon had made another mistake when they released RF.

Not me. I've been shooting with Canon RF for almost 2 years now, and it's magnificent.

The mount looks too big to be shared with APS C bodies since they have to give up small form factor.

Thus EOS-M! It was viable back with EF, and it's still viable with RF on the scene. I'm living proof! Vive le 'M!! Vive le 'M!!

Let me know when you can mount a RF lens on a M system body.

Don't have any desire to.  I love my EF-M lenses.  All of them.

And I love my RF lenses on my R bodies.  (actually proves my point)

Considering Sony's latest lenses, I doubt Canon and Nikon's argument for a bigger mount. Canon must have thought that they would use RF only for fullframe and they needed a totally new, better mount for their future.

Again, it can be used for both FF and crop. Just like EF was. For minimal expenditure.

Would Canon really have chosen 54mm if they had not had EFM?

Certainly. It allows for improved lens designs!

It is also the same diameter as the old EF mount.

EF is dead.

Although RF is not good for compact APSC bodies and Canon maybe has to give up EOS M

Canon might (might!) give up on EOS-M, but we don't have to.

I think, however, Canon would not be able to avoid using RF for APSC bodies in the end.

Right. Why develop another APS-C mount when it's not needed.

It is a better mount in terms of technology, and their focus has been always on fullframe market, apart from the inefficiency of keeping two mounts.

EOS-M is operating all in The Black for Canon. Even an M6 Mark III "firmware upgrade" would cost them next to nothing.

The same could also be said for the entire EF-S lineup of bodies and lenses.

They're all dead too.  And sooner than EF-M.

What do you think? Which of the following would be the best solution?

The best solution depends on what you're shooting, and how. IMHO it's great to have a number of excellent choices... Rather than the other way around.

Great for the consumer, but not so great for manufacturing efficiency and Canon's bottom line.

Actually my argument is that it's good for both!  Horizontal market saturation!  Squeeze everybody else off the shelf!  Works.

R2

BirdShooter7 wrote:

R2D2 wrote:

The M occupies a niche that cannot, will not, (not in anyone's wildest dreams!) be filled by a crop RF body. ...and to your point it is the diameter of the EF-M mount that actually guarantees this!

I have some serious doubts about this. Time will tell.

I just don't see Canon replicating my beloved M6 Mark II form factor with the R10.  No way, no how.

The R10 will be bigger, have a built-in EVF, be bigger, have an articulating LCD instead of a tilting one, be bigger, won't be specced nearly as well as the M6ii, and be bigger. 

End of story!

Vive Le M! 

R2