Telextender Questions

What would happen if I tried to use my 1.4x with a lens that is not on the list of compatible lenses?  Would I lose the autofocus capability?  The automatic exposure control capability?  Some other capability?  Or would it simply not function at all?  For example, if I wanted a closer close-up shot of the moon, and would willingly set the focus and exposure manually, could I get the 1.4x to work with an EF 75-300?

Similar question:  Can I stack my existing 1.4x with an (as yet unpurchased) 2.0x III, attach my 70-200 F4.0L, set the focus and exposure manually, and get a net effective 560 focal length?  Would it work at all, or would the camera refuse to fire because it did not recognize the presence of a compatible lens?

If it impacts the answers, my camera is a 5DII, and my wife's is a 60D

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