ZWO EAF ( Electronic Automatic Focuser)

  • 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.
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  • Regular price $199.00

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ZWO EAF ( Electronic Automatic Focuser)

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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Customer Reviews
4.6 Based on 10 Reviews
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Paul L.
United States United States
Smooth, quiet, accurate, affordable...

Another great ZWO product. I had been looking to get an EAF, but they were out of stock everywhere. Finally saw OPT had one left in stock from a new shipment, and I jumped on it. Glad I did! It mounted easily to my WO Z61 refractor, no modifications necessary to scope or the EAF bracket. It operates smoothly and quietly, and is fully ASCOM compatible. I was using it for autofocus in NINA with success the first night. Best value out there for a motorized focuser accessory.

Blaine K.
United States United States
One of the smoothest electronic focusers

The ZWO EAF is one of the best thought out designs I’ve seen. First thing you notice out of the box is the high quality machining that is silky smooth to assemble. I mounted this onto my Orion Crawford focuser. Nothing fancy. I used the included screw to replace the lock thumbscrew. It’s not needed with the EAF. In the box comes a number of flexible adapters to fit a wide range of focusers. It was rather easy to install and took about 15 minutes. I planned to use this with the ASIAir and works seamlessly. Using the asiair app I can now control the focus with my iPad or phone. I also noticed that the stepper routine they use is much more refined than what’s used on the pegasus motorized focuser. Focus is smooth with little vibration compared to pegasus. I cannot wait for the hand controller to come out so I can also use this for outreach events. For now my astrophotography has elevated to a new level. I highly recommend this if you are an asiair user or have an ascom or indi set up to control the unit.

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.

John D.
United States United States
Service not what it used to be

I had some trouble getting a response from OPT. My first inquiry was to an email to a specific person who I had worked wiht in the past. No response. Then I sent in an inquiry via your web page. No response. Finally I contacted Jake by calling and he was able to help me. I later found out that the first person I tried to contact no longer worked there? Then, to cap it off, the unit arrived but had no power supply. Now I did find that the parts list on your web page did not list a power supply and I missed that. But it would have been nice if the sales person had informed/asked me if I needed one. Wouldn't this be a good upsale opportunity? I have purchased close to $4,000 in equipment from OPT this year and have been a customer since the mid-1990's. In the past I appreciated the great customer service and the ability to visit your business and confer with experts about my needs. I was surprised when I tried to will-call an order that this was not possible. Why no will-call? At this time OPT offers me no different service than a dealer located anywhere in the country. I have in fact started looking at other dealers and OPT has lost its position as a preferred source for me.

Robin R.
United States United States

So far so good it’s working, more later

Jon G.
United States United States
Generally, Excellent with a few minor "quirks"

The focuser works very well as part of my INDI system (Kstars/EKOS), and even matches the red decor of my ZWO ASI5300MC Pro main camera, ZWO OAG and ASI120 Mini guide camera. If I were to "redesign" the focuser, I'd make it able to disengage from the mechanical focuser (like the Rigel Nstep, which I have on another rig), for quickly opening and closing without being powered on. There's a little lag in engaging the mechanical focuser after you stop and reverse direction, and I like that as it enables me to have a small window of manual fine focus, if I like. The hand control is useful when it works, if you want to focus your scope without having to activate your astoimaging software, but for the extra $40, I would expect a better made accessory -- it's a flimsy piece of hollow plastic with switches that have contacts that are very finicky. Not at all what I expect from ZWO. OPT, as always, was superb. They nearly always have what I need, and get it to me in a day or two by US Mail (helps that I live down the road in San Diego!).