ianwood
Taco Wrangler
Here's a screen grab from the DJI official youtube channel, look how close he is to the phone or tablet, and he's wearing a watch...
View attachment 40093
Yup. And he's on a beach. Many beaches have iron content.
Just as a note of caution to others: You may have gotten away with calibrating with your watch on or your phone in your other hand or on a beach but it is generally ill advised. The compass is the most vulnerable component in the system. If you really want to be sure to get a good calibration, all metal objects especially ferrous metals should be at least 10ft away.