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Using a ZWO EAF Focuser when Observing

Accessories Cassegrain Celestron Equipment Observing SCT
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#1 sandconp


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Posted 18 September 2021 - 09:21 AM

I have a question about the ZWO EAF (Automatic Focuser) that I recently bought.  Even though 90% of my work is imaging, I still like to do visual periodically. I have been trying to use the Automatic Focuser manually when I do visual with the manual hand control that came with the focuser and I seem to reach my limits very quickly and I get a beeping sound.  So I can't get the image I am looking at in focus so I take of the focuser off and just use the manual knob to get focus.  Then when I go back to imaging, I just re-install the automatic focuser.  There has to be a better way to switch between visual and imaging without having to take off the ZWO EAF.  Do I need to use a PC with the ZWO ASI Suite software to calibrate the focuser?

#2 Walter T

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Posted 18 September 2021 - 10:16 AM

The ZWO EAF has a travel limit around 60,000 steps.  If your focuser travel range is longer than that you'll run into the situation you're in.  What you can do is figure out if your visual  and your imaging configurations will come to focus within 60,000 steps of each other, if so then move the focuser to a position just before your first setup comes to focus and set that as your Zero position.  If they don't come to focus within the 60,000 of each other then what you'll need to do is move the focuser all the way in the direction that you want until it reaches it's limit then reset the position to Zero if you want to continue moving out or 60,000 if you want to continue moving in.  I unfortunately need to do this dance when switching configurations on my SCT as it has the equivalent of like 350,000 steps in travel range.


You will need a PC, Laptop, or ASIAIR to reset the focuser position but hopefully if you are in the first scenario you'll only need to do it once.  Hope this helps.

Edited by Walter T, 18 September 2021 - 10:17 AM.

#3 Forward Scatter

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Posted 18 September 2021 - 11:56 AM

In ASIstudio you can also set the EAF limits and whether to beep or not. Go to the Deep Sky Imaging tab then click on the focuser icon. You may have to play around with the step numbers; for instance I set the value to "0" for the focus tube all the way in then choose some random # of max steps and use the "move to" until the tube no longer travels. This will be your max # of steps for your scope. 


These values will be stored within the EAF and will appear in whichever imaging program you use, plus within the ACSOM device hub. 

#4 sabant  Happy Birthday!


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Posted 20 September 2021 - 04:22 AM

Maybe a practical solution would be to add an extension tube when being visual?

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