This is helpful. I have been told to do this calibration on the ground when the craft is stable...no movement. In this video, when they get ready to actually press the calibration option on the screen, the voice over instruction says to point the lens at the horizon...the video shows the camera pointing directly downward....a bit confusing. But I'm happy DJI has listened to us and has provided some sort of official procedure to do this calibration.
I am happy with my images, video and photo. But I have never been totally confident that my lens is calibrated properly.