How far from metal objects does one have to be when calibrating the compass? I was flying yesterday and noticed I had a lot of drift while hovering.

Thank you for the info. I've looked thru the manual but must have missed it. I do travel some with my drone but I always recalibrate before each flight.

At what distance away from my normal flight area  would you recalibrate. I usually stay within 10 miles of my home flying area. But occasionally I travel to my home town which is 75 miles away.

Thank you for all the great info. I never thought about underground metal objects. I'm going to recalibrate in my neighbors field as I also have a small yard beside a cemetery. I may use my metal detector to find a clear area. Again thank you so much.  

"How far from metal objects does one have to be when calibrating the compass?"

Depends what the metal objects are.  

If they are overhead or underground power lines then you want to be at least in the next field and preferably a lot further.

For most metal or reinforced concrete, 10 meters is probably enough, make it 20 just to be sure.

Once you have a good calibration, don't recalibrate unless you move more than 1000Km, or it is more than 6 months since your last calibration.  

Although the aircraft may not go out of calibration over time, you should still calibrate at least once a year since the earths magnet field changes over time.
Also recalibrate if you modify the aircraft in any way, adding any metal to it will affect its own magnetic field.