Re : Re: [ap-ug] ZWO EAF

Yves Laroche

Hi Joe,

Unfortunately, these twist clutch systems may suffer from slippage.  Normally they are installed on the reduction side axis of the focuser NOT on the coarse knob side.  The reduction side mechanism could introduce some slippage during the night.  It's not a focus motor problem but it's related to how well machined is the focus reduction mechanism.

I bought a chinese refractor more than a year ago and also bought a focus motor build by Optec.  Unfortunately, I got plenty of slippage during the night and finally found it was due because of the friction reduction mechanism.  Sometime, when telling the focuser to go home (Step = 0), at the end of the night, the drawtube was out by an amount of 500 steps. By chance, my focus motor was completely refunded, and I bought the EAF instead.  The EAF is built to be installed on the focus coarse knob side.  Never got slippage with that setup since then.

For people using autofocus at each filter changed, the slippage is not really a problem but if you are using automated system, it could be a problem if your filter offsets are not already computed.  When using the ACP FocusOffset script, I was really not confident concerning the offset values because of this problem.  Last summer, I was able to get good offset values because there was no slippage at all.


Le 27/09/22 22:28, "J. Belden via" <jjb4469@...> a écrit :
Yes, another vote for the Optec, cleaner look and accurate positioning.  I have a ZWO EAF on another scope, you get what you pay for is all I will say.  The Optec is nice because of the twist clutch engage/disengage something the EAF doesn’t do.
My thoughts were I waited for a long time for my 130GTX, plus spent some money so why cheap out on the focuser motor controller.


J. Belden


No slippage on my AP130GTX for sure, the focuser is very stout, don’t expect any issues.
I do have the ZWO EAF on my TOA130 and agree for the price it works pretty decent and since I planned on selling my TOA, I didn’t bother buying another 3.5 Nightcrawler which did save my 3k.