Sreesha2024

On 11/10/2019 at 18:41, Barns said:

So, I've had the chance to play around a little bit more with the EAF this morning. I used SharpCap's edge contrast focus mode to autofocus on distant buildings, which seemed to work quite well. However it's thrown into light what I think is the real underlying problem with the EAF at the moment - the backlash is HUGE.

I've followed ZWO's methodology to measure the backlash - drive the focuser 1000 steps one direction, then use the fine focus adjust buttons to move 10 steps at a time the opposite direction until you see the physical fine focus knob on your scope move. Count how many clicks of the fine focus adjust button it took before the physical focus knob moved, multiply by 10, that's your backlash.

Mine comes out at ~850! Which is higher than the max value you can input on the EAF ASCOM configuration (max is 255). So I can't even compensate for it in software (not that I'd want to leave such an obviously wrong thing alone without fixing it, anyway). You can actually SEE the backlash, if you tell the EAF to move a large distance opposite to where it's just been moving, there's about ~1s delay where the EAF is whirring but no movement on the scope focuser. Seems very wrong.

What might be causing this huge backlash? It's not the scope focuser itself - that moved perfectly back and forth without the EAF fitted - the Esprit 100 focuser is a lovely unit from what I can tell. I believe I've fitted the EAF tightly such that there's no "play" between the motor and the focus shaft. What might be causing this scale of backlash? Is it likely to be something internal to the EAF unit itself? I should note that this is the customer-returned EAF I got cheap from FLO but it does have a guarantee so I'll return if needs be...

Edit: something I forgot to mention, I had understood that with the EAF fitted the focus knob would be held tight i.e. you wouldn't be able to manually focus. This is fine, however, it is not actually held fully tight by the EAF in my case - you can turn the coarse focus knob about 1/5 turn (ish) back and forth before it's stopped by the EAF. I THINK this would roughly correspond to the backlash amount judging by the travel on the focus tube when manually turning the knob this way (NB the tube moves immediately back and forth, no backlash between knob and tube). What fault might this indicate, in the fitting or in the EAF itself?

I have same issue.  I have backlash of 450 with C Edge 8.  How to increase backlash beyond 255 in AAP+  Please advise.