Finally some success autofocusing FSQ85

I am not using a reducer. Spacing is not a factor.
Anyway bad weather next week so I can’t do more testing.
Really need another hobby for bad weather.

It has nothing to do with a reducer, the spacing between the rear elements of some flatteners and the sensor can be critical. I don’t think the optical design of the FSQ is like a traditional telephoto lens, where the spacing is determined by the focus extension. (The cutaway drawing on the Tak website is ambiguous - but the back two elements could move with the focus tube.) I number of threads in other forums point to incorrect couplings with the wrong depth, especially T couplings.