This thread is almost 2 years old.

I know of no way of only partially lighting the sensor with any given lens at the appropriate format, so the correct answer is that the whole sensor will be exposed and the camera's firmware will adjust to the new image size. That can easily be proven as the crop ratio would change visibly if only part of the sensor is used. Putting a crop frame lens on a full frame sensor is the only way to not use the whole sensor and in cameras that accept this arrangement, the only way to fool the camera is to use a manual lens with no electronic contact with the camera.