You aren't guaranteed the EF-S lenses will cover a full image circle. That pretty much kills the discussion, I think.
Again, no. the whole idea of the EF-S lens is that the rear element is *really really* close to the sensor. Just how you intend to tweak a mirror so that it becomes smaller but still covers the same area is beyond me.
EXACTLY like Nikon have done.....
You do realise Nikon's DX doesn't work the same way as Canon's EF-S?
i meant in technology point of view....
...and is not very hard ( in terms of technology) to adapt the APS-H mirror to be compatible with EF-s lenses.
Personally, 1.3X might not be a totally terrible compromise, though it would alter the field of view I get out of my lenses. So long as any change meets the criteria I laid out above I'm down with it...but only if it meets ALL of them.
No one says to keep the full resolution of a APS-H sensor when an EF-S lens is used. I mean when you will use a EF-s lens on a... say... 20MP APS-H sensor you will have 12-13MP effective resolution ( the camera will crop the 1.3 sensor to 1.6).