The ZWO EAF has an optional hand paddle that you can adjust the focus manually. But when you use it, it does adjust the count in the EAF itself. And that's why I have one for each of the units I have. It makes it handy whenever I want to do live viewing with the scopes also.
There may be some EAFs out there that has a clutch to disconnect from the shaft, but I don't see any way those can keep up with the number of rotations on the device with the focus assembly travel since they are not bound to each other any longer.
Not really different than when you loosen the clutch on your mount and move your scope. It may say it's pointed one location but once you moved it manually that location fix no longer applies.

Read More...