When I am flying and filming I am noticing the Phantom moves vertically up or down when I am not moving the throttle stick up or down. If I am flying in a circle around something and filming it will descend slightly instead of maintaining a consistent altitude. I have used a Futaba radio on a F550 and don't recall this being an issue. I assumed with the self centering stick on the Phantom 2, this would be even easier to maintain. Are there any settings I can change to fix this or is this just the characteristics of the copter? I know it is small and light, but still powerful. Thanks!