I have the exactly ND filters you have. I had used the variable ND filter and the UV filter several times without any issue. These filters are very light and I don't see why it could affect the gimbal. Most probably your gimbal is having some issues.
Sent from my Nexus 6 using Tapatalk
That's a lovely bird, where did you get the metal frame on the back? I'm thinking of adding a tiny camera or Raspberry Pi camera as extra payload for infrared photography. I'd need some kind of frame or support to keep the camera stable and pointed downwards.
