1.If the Nikon camera is in full frame mode then the image is circular, because half frame Fuji mirrorless lens cannot cover the Nikon full frame cameras

2.Nikon full frame cameras need to be set APS-C mode

3.Nikon cameras cannot shoot in full frame mode

4.The Nikon ZFC Z30 Z50 does not have the above issues when used

5.Nikon Z9, Z8, ZF, Z7, and Z6 are full frame camera.so the image is a circle, you can only switch the camera to half frame to use it