I finally own a decent follow focus. It's a used Zacuto Z-focus. Works great, smooth turn, zero play.
I'm using it together with a Sigma 18-35 f1.8, with a this ultra cheap focus ring: https://www.amazon.c...ewer focus ring
The Sigma lens itself has a buttery smooth focus turn, and like I said, the Z-focus is basically silk when it's just spinning by itself.
But the moment the Z-focus is actually put to use turning the Sigma lens, it takes a little more effort to turn than I feel it should, and there are some subtle vibrations in the movement. Adds up to a less-than-stellar focusing experience.
I had a similar problem when I first got the Sigma and the Z-focus. I'd bought a gear ring that was specially fitted to the Sigma, and it proved totally unusable--vibrations galore.
Is this a normal problem with cheap, crappy focus rings? I can't find anyone else who describes experiencing this issue quite like I have. Help!