I've got a couple of 500mm mirror lenses, which are as widely acknowledged, difficult to focus.
I'm looking for DIY plans to build a follow focus TYPE device to help me move the focus rings in very small increments.
The problem that I've run into is that while I've found a lot of suggestions, almost all of them are for video, and rely upon the sort of video dual rod mount which I don't need and will never use for its intended purpose. I literally have no intention of EVER recording video.
The one or two exceptions I've seen seem to be designed for mirror lenses different from mine.
What I'm looking for is something relatively simple that's designed to attach either to the tripod socket of the camera or the auxiliary threaded hole on my "L" bracket.
I have a moderate selection of tools, but no ability to bend heavy metal parts, weld, etc.