Camera mount engineering part2 – Can there be a Canon full frame mirrorless?


Can there be a Canon full frame mirrorless?

Follow up from my previous post discussing about the camera lens mount, few people maybe aware of the limitation of Sony full frame mirrorless due to the limitation of the mount. So my next question is, despite last year’s rumor, with the given diameter of the EOS-M EF-M mount, does Canon has the potential of correcting its EOS-M from Sony’s mistake?

To do that, with little information on the diameter of the camera as I do not own any EOS-M, I decided to do a very unscientific photo comparisons.

EOS 7D II, EOS 5D III, A6000 and A7II.

First, I collected high resolution images of EOS 7D II, EOS 5D III, A6000 and A7II, using photoshop, overlay the screws and the lens mount to get as to scale as possible of the direct comparison of size. Note there is a big variable that could lead to inaccuracy; the ‘official’ photo of the camera may be taken with different focal length, which could render a perspective difference of the actual sensor size. Nonetheless, this is the closest I could get anyway.


Next, compare the sensors side by side, so all 4 images are to scale.


Finally, I matched up EOS M3, and copy the full frame sensor onto M3 (Above) to see if the edge could get blocked off by the bayonet like the A7 did. The image above was brightened up so see a better contrast.


Conclusion, would a full frame EOS-M make a better camera than A7 without having the protrusion edge issue for wide angle lens? From the very unscientific measurement, the lens mount of EF-M has a very minute difference, bigger than the E-mount. The superimposed image could indeed fit in the EF-M bayonet slightly better than the E-mount, though very very close on the left side, considering the mount from the lens need some clearance, its difficult to say if it can fit in fully.

Which I raised another question; another factor that is the clearance of the flange distance. Both EF-M and E-mount has a flange distance of 18mm, which doesn’t give EOS-M any advantage to clear off from the bayonet.

As consumer/photographer, we welcome the competitions between the camera companies as it will only bring us better and more affordable tools. As an engineer, solving one problem usually raise another or more problems, we can’t really blame the engineers for not having a future proof design.. Let’s hope to see Canon or any other company (*cough Leica*) can come up with a better full frame mirrorless system.

Cross section of Olympus E-P1 shows the clearance between the bayonet and the sensor.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s