[davidmanze]

Adapters are NOT an issue, generally. They have worked well for decades. The extenders/teleconverters always have been used with heavy tele lenses too. The Canon macro extender for the 50mm f2.5 macro also works just fine without "centering issues" The Canon FD to EOS adapter for longer tele lenses also does what it is supposed to do. The Canon EOS to Ef-M adapter, no complaints either. The different Sony A-mount to E-mount adapters, same story.

 

The many stories I read about adapting EOS lenses to E-mount, either with optics for APS-C only, or without. None talk about such issues.

 

Then there are the many 3rd party adapters that work just fine without problems. 

 

If an adapter would introduce a big tilt (none does...), you would get a tilted focus plane, not a centering issue.

Agreed then BC!   

 

   Just one thing isn't de-centering a tilted frame, double elements poorly aligned/ poorly mounted?