Hardware Attaching the ZWO EAF to an Apertura 72mm APO refractor

This guide will help walk you through installing a ZWO EAF on the 72mm Apertura refactor telescope (APT-72EDR, and most likely the 60mm little brother of it) that is sold by High Point Scientific. This telescope is the same as offered by other vendors, simply rebadged. So the process should be similar for any of them. It had me scratching my head until I finally figured it out.... so thought I'd try to save others some time that may have the same style telescope and wanting to put an EAF on it.


You will want to use the coarse focuser knob for the EAF to attach to.... and the first thing you will find is that there are no holes in the knob to remove it.
That's because they are hidden by a grub screw on the bottom of the focuser​


You will need to take the first grub screw out, then slightly rotate the focuser and you will find two more grub screws further in holding the course focuser to the shaft. Align the hole to the lower grub screws and then back then off slightly and then the knob should slide off.


Once you have the coarse adjustment knob off, you will take one of the flex shaft extenders that fits the shaft and slide it over the coarse adjustment knob shaft. You will want to have the grub screw that you originally removed still out, as you are going to need access through there to tighten down the grub screws on the flexible shaft. Be sure at least one grub screw is located over the flat portion of the focuser shaft, which should be aligned with where you removed the grub screw. Use the supplied wrench and tighten that grub screw down, then slowly rotate the focuser knob to get to the other one.


You will most likely find that the supplied screws are not long enough to attach the aluminum frame to the focuser and then to the EAF. I used 2 pan head Phillips machine screws (M4-.70 x 10) and attached the frame to the focuser using the two screw holes provided.

For use on my EQ35 Pro mount, I did have to rotate the focuser to the top of the telescope tube, resulting in moving the guide scope that came with my equipment.

About author
I've been interested in astronomy since I was in Jr. High (graduated in the early 80's).
It wasn't until I retired that I was able to really get into it due to monetary and time constraints.


Thank You! I couldn't figure out how to get the knob off. With your instructions, I was done in under 10 minutes. Now to calibrate!
Thank You! I couldn't figure out how to get the knob off. With your instructions, I was done in under 10 minutes. Now to calibrate!
I'm glad you got some use out of it... it drove me batty until I figured it out.

Guide information

Tracy Perry
Article read time
2 min read
Last update

More in Guides

More from Tracy Perry

Share this guide