In my early testing I did a lot of tests with a lot of expensive RC servos (consider supporting Medlin Drone), only to find that each new servo had the same twitchy movement of the last, even the programmable servos tuned to maximum dampening vibrated the camera when moving.
But then I tried the LDX-218, just because the reviews had “smooth” in their description and despite it not being made for RC. The first time it moved was magical for me, it slowly started moving from one position and softly settled into the next, I had found a solution.
It turns out I had been looking in the wrong places, as RC servos are made to be quick and responsive, not smooth, what I needed was something designed to move naturally, like a servo designed for a robotic arm… it took me hundreds of dollars and many headaches to discover that. So for whatever it’s worth that’s what you need, a robotics servo, not a RC servo.