Hello guys !
At the first glance your calculation is right, i've found the same result of 14.2mm when i did ot the first time too.
I've redone the calculation a second time (after the measuring the distance between the mount and the mirror in upper position on my rebel) and i've found 12.8mm (which approximately matches the adapter lenght and the spacing between mount and mirror in a rebel).
If this patent really exists and if canon released such a thing with a new mount, it will be very exciting !
It means that they will split the EF/EF-s systems into two distinctive systems ensuring in the same time a full retrocompatibility from up to bottom.
IMHO, what i've red about future canon decisions, they won't make MIRRORLESS, and for me that's a good thing.
Nonetheless, they claim their will to make a decent compact dslr alternative for canon user's with a mirror !
They know that most of their users do not want to get a rid of an OVF.
What we could see and "extract" from the patent diagram:
- The new mount's throat is slightly smaller.
- It's a 12.8mm adapter that will accept actual EF-S Lenses. => The new system will keep the actual APS-C (1.6x crop factor) sensors.
- The pin connectors on the newer mount side are the same as EF's ones, they just added 3 extra pins, so the communication protocal would be same as EF.
(olympus did the same when they created micro four third from original four third mount, in order to add a high speed communication port between body&lenses for video functions. Even Sony did exactly the same Alpha/Nex. )
- The pin connectors are located on the right side of the camera and vertically mounted.
=> Can we imagine a body with vertically mounted sensor ?? Why not, Olympus have already done this with the original compact half frame Pen FT and it got a fixed pellix mirror. Canon have experience with pellix, just see the EOS RT.
Canon could even make a camera with a slapping pellix mirror for a liveview mode with better IQ if the optical finder isn't needed.
- The new mount will have a 12.8mm shorter register than EF. => ~31.2mm register. That's enough to keep the APS-C mirror box in a tight fit.
- A shorter flange back have two main advantages for optical engineers
*It's easier to make wide angle lenses more compact with less vignetting and aberrations and even brighter
(ex: leica M lenses )
*A complete compact prime lenses offering (APS-C image circle) would make more sense for a smaller mount.
They gain 12.8mm whereas a compact prime could only measure 20mm in lenght (example: sony E 16mm 2.8 or voigtlander 20mm & 40mm SLII pancake).
As a conclusion, the new system would be a sort of "shaved" or "receded " EF-S mount but still with a mirror box.
I wonder how will they name this new sytem, EF-SS (EF-Small Shorter) ? EF-S minus? EF-S Evolution ? EF-S v2.0 ?
Plus we can imagine the dimension of the new body, it's quite obvious:
*Grab an EOS Rebel/Kiss/XXXD and put off the 12.8mm on the mount.
*Put-off the pop-up flash above the pentamirror and replace it by a built-in tilt-up flash located on the left of the body.
*Remove the protuding grip for the right hand.
*Put SD or even micro SD card and a smaller battery.
*Mount a bright compact prime ( 30mm f/1.8 ) or a "pancake" lens.
=> You obtain a compact APS-C sized sensor DSLR with an OVF with the dimension of an Olympus EPL2 and its 20mm 1.7 pana prime !
**Create an optional battery-grip if needed to obtain a pro dslr in reduction .
PS: I apologize for my scholar english, english is not my first language.