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ZWO EAF ( Electronic Automatic Focuser)


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  • Great for Planetary and Deep-sky Imaging.
  • Hand-free Control from your Smartphone or Tablet!
  • Supports ASCOM, ASIAIR, and INDI.
  • USB HID Device and Drive-free.
  • Step Motor, 5760 Steps.
  • USB 2.0 Data Port.
  • Load Capacity of up to 5 kg.

Product Details

  • The ZWO Electronic Focuser enables precise, dynamic focus control for planetary and deep-sky imaging!

    The Standard version includes the EAF Body, flexible coupling, motor bracket, USB 2.0 cable. 


    5KG Capacity, ASCOM & ASIAIR Supported. The ZWO EAF works with all capture software supported by the ASCOM platform. The focuser also completes the ASIAIR WiFi imaging and control system. Control your entire imaging runs from a smartphone or tablet, even from indoors!


    The changing Airy Diffraction pattern inspires the Design of the body through a range of focus

    The EAF is constructed from an all-metal housing in an attractive red color that matches ZWO cameras. 

    ZWO Electronic Automatic Focuser (EAF)


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Product Reviews

Customer Reviews
4.6 Based on 13 Reviews
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  • track
  • autofocus
  • ASIAir
  • couplings
  • refractors
  • Edge HD C9.25
  • hand controller
  • knobs
  • motor
  • improvement
Billy G.
United States United States
Love it!

Makes focusing so much easier due to the OTA remaining stable unlike when done by hand. Just got to remember to retract the focuser before shutting down to pack up as there isn't a clutch so you cannot move it manually.

OPT Telescopes ZWO EAF ( Electronic Automatic Focuser) Review
Paul A.
United States United States
Cannot fit to my Celestron 6SE

So far I've not been able to figure out how to link it to the focuser of my Celestron Nexstar 6SE (which is not exactly a rarety - it's listed on Amazon as a "best seller") .The shank of the focuser knob (even after removing the rubber sleeve) is far too wide to accept any of the provided flex couplings, and even if I could I don't see how to mount the EAF unit body to the tube of the telescope without drilling holes etc.

Gary B.
United States United States
Use Your Head!

This is my first EAF and it works GREAT. Just read the instructions and it works well. Don't read and follow the instructions carefully you may be frustrated.

United States United States
Mounting EAF on Celestron Edge HD C9.25

I received the EAF and hand controller with the ASIAir Pro kit. The brackets and couplings it came with are really designed for refractors. I wanted to mount it on my Edge HD C9.25 since I wanted to use the ASIAir to autofocus. I designed and built a small bracket with movable track for the EAF. I had to gear up the motor with a 40 tooth gear on the EAF and a 20 tooth gear in order to get reasonable focus speed with the handcontroller on FAST. Slow is really slow. Then I found out that a guy on Cloudy Nights was selling a printed movable mounting bracket for the EAF on the C9.25 that looked and worked a lot better than mine. I ordered one from demarko69 in the CN classifieds. It comes with a stereo litho printed knob with a GT2 45 tooth gear, belt, small gear for the motor shaft and top and bottom brackets. I ordered and installed one. It works well using the 40 tooth gear I already had. It's fast enought in the FAST mode and it is mechanically an improvement over my design. It also allows loosening two knobs, moving the EAF away so that the belt is slack allowing manual focussing if desired. I am quite impressed with how well this all works with the ASIAir and it makes the EAF a very useful addition to my scope. See the photos.

OPT Telescopes ZWO EAF ( Electronic Automatic Focuser) ReviewOPT Telescopes ZWO EAF ( Electronic Automatic Focuser) ReviewOPT Telescopes ZWO EAF ( Electronic Automatic Focuser) Review
Ron H.
United States United States
Great focuser for the money

I already had another focuser that was/is amazing.. I needed the EAF because I really wanted to run ASIAir Pro setup. I was a bit concerned going to the EAF, but must say I have been very impressed. My backlash is only about 25 and is literally zero impact. I took good care when installing to ensure things were as "wobble free" as possible. I have had great focus.. great V curves in NINA and as I said no backlash issues. In fact the Sesto Sensa 2 I have doesn't really seem to control any better.. even at considerably finer steps. The EAF has about 34,400 count range for me and the Sesto Sensa 2 has about 185,000. I don't see any better performance from the Sesto.. this EAF gives me what I need and only take it down to 10 typically. I will say that the "zero" of the EAF seems MUCH easier to deal with than my sesto.. which seems to require rezeroing in seperate software. The EAF just run it in and set to 0.. done. Highly recommend.

Robin R.
United States United States

So far so good it’s working, more later