35mm Crop Mode (GFX)
On the camera body, you may set the coverage of the lens to medium format, full frame. By default, the camera chooses between the two automatically.
EF-GFX Smart ExpanderTM and EF-GFX Smart AdapterTM sets all full frame lenses' coverage to medium format by default. To change the crop mode of a particular lens, power off the camera while holding down the push button on the Smart Expander or Smart Adapter. The next time the camera is turned on, the crop icon is indicated on the LCD. Hold down the push button on the adapter again and turn off the camera to cancel the setting. Each lens may have a different setting and the adapter will remember the crop mode of each lens separately.
EF-GFX Smart Expander and EF-GFX Smart Adapter may not work with APS-C lenses. Canon EF-S lenses have a rear protrusion which will interfere with the optics of Smart Expander and will not fit at all. Third party DX/DC lenses may fit but may have vignetting problems. Smart Expander and Smart Adapter will try to identify APS-C lenses and turn on 35mm crop mode. That can be turned off by the same procedure of holding down the push button and turning off the camera.