Greetings everyone!

I haven't given up yet on building a ULF camera.

I've been researching as many designs as possible but I have a question.

After you move your standards around to get close to having the subject(s) in focus, how long would people recommend a fine focus mechanism should be?

Edit* - I think the easiest to do design is one MAubrey is working on.
It's a carbon fiber tube design.
The only thing I'm thinking about adding is a fine tune focus mechanism.

Does anyone know existing camera parts that could do the job.
Something like this:


https://i.ebayimg.com/images/g/N4EAA...2aq/s-l300.jpg




Thanks for reading this!
Have a great weekend!
Cheers,
Kevin H.