EAF Focus Position Drift

JeffMorgan

Over the last two years I have noted a slow drift in the initial focus position of all three of my EAF 5v focusers. For example, if NINA comes up with Autofocus position 32000 on Night One, the following night the best focus position will be somewhat higher - something like 32080. This behavior seems to be cumulative.

Last night the EAF attached to my RedCat (purchased new about one year ago) changed position by an astounding 4000 steps lower.

This is not a very desirable behavior, is this common to others? Is there a fix?

w7ay

JeffMorgan Last night the EAF attached to my RedCat (purchased new about one year ago) changed position by an astounding 4000 steps lower.

Make sure the focuser lock ring of the RedCat is completely disengaged. Use some Gaffer tape to make sure it is well away from the infinity lock position, and do not try to refocus to a terrestial object unless the focus is also not backed up against the lock ring.
Check the belt to make sure it is sufficiently tight.
Listen for double beeps from the EAF. That happens when something has reached a mechanical limit.
It the above does not work, update EAF firmmware to at least v 3.3.5.

I use about 9 ZWO EAFs on everything from an FSQ-85 (direct drive) to a small Askar 180p (belt drive), and none of them exhibits the behavior that you descibed.

Chen

JeffMorgan

w7ay

You were right about the lock ring, somehow it had settled in to provide friction and slipping.

I will also update to the latest firmware this afternoon.

The drifting of focus position is also exhibited on two other EAF units, one my FSQ85 the other my TMB130, both direct drive. It would be tempting to say the EAF does not store this position, but then I would see random numbers.

w7ay

JeffMorgan one my FSQ85

Remove the focuser locking knurled knob completely, and replace it with an M8 setscrew. Make sure the set screw is not tightened, but simply acts as a grease seal.

Chen