I like to change my zoom and focus during the shot, like for a rack focus effect, or the ever-popular camera stunt, the dolly zoom or "Vertigo effect."
But I'm getting repetitive stress disorder from holding my hand funny around the lens barrel, and it's hard to adjust two rings with one hand while my other hand is holding the camera up.
I want a follow focus! And I don't want to pay several hundred dollars for it.
I saw recently an image and video of this way to make a follow focus out of hardware store parts... but while the design is simple, I couldn't find any instructions on how to make one. So I've written up my method so people can make their own.
- be gentle with your camera. As with any mod, it's possible to smash your lens if you aren't careful, and I probably don't have to tell you that would cost a lot more to fix than the cost of a commercially-produced follow focus!