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Sharp focus all night without touching the telescope
Why we like the EAFN:
- Focus that keeps up with the temperature: as the night cools, your telescope's focus drifts. The EAFN lets the ASIAIR or N.I.N.A. refocus automatically every so often or after a filter change, so late-night frames stay as sharp as the first ones.
- No more bumping the scope: focusing by hand shakes the image and can shift your framing. The EAFN moves the focuser in tiny, repeatable steps while you watch the stars on your phone or laptop.
- Simpler cabling: the new version uses USB-C for both power and data, so one cable from your camera's USB hub or the ASIAIR does it all.
- What we tell customers: it's one of the first upgrades we suggest after a mount and camera, and it works on most refractors and SCTs with the included bracket or an inexpensive model-specific one.
The ZWO EAFN Electronic Auto Focuser is a small stepper motor that bolts onto your telescope's focuser and turns the focus knob for you. Paired with the ASIAIR or a computer, it runs autofocus routines that find best focus by measuring star sizes. It's the standard version of ZWO's new-generation EAF, with a metal housing, a 5kg (11lb) load rating and a USB-C port, and it weighs just 215g (7.6oz).
Key specs: stepper motor with 1:128 reduction · 5kg (11lb) focuser load · USB-C power and data (5V 500mA) · ASCOM and INDI · works with ASIAIR · hand controller and temperature sensor ports · 215g
What it does for your images
- Autofocus at the start of the night: the ASIAIR or N.I.N.A. steps through focus, measures star sizes and lands on best focus in a couple of minutes.
- Refocus as it cools: set it to refocus after a temperature change, a set number of frames, or each filter change on a mono camera.
- Repeatable positions: save the focus position for each filter or camera and return to it in seconds.
- Remote focusing for planets: fine-tune focus on Jupiter or Saturn from your laptop without shaking the telescope.
How to install it
Remove one of your focuser's coarse knobs, slide the matching flexible coupling onto the focuser shaft, then attach the EAFN and its bracket to the focuser using the supplied screws. Four couplings in different sizes and five spacers are included, so the standard bracket fits most Crayford and rack-and-pinion focusers. Celestron SCTs and Takahashi refractors need a model-specific bracket (see below).
Software support includes ZWO's ASIAIR app and ASIStudio, plus ASCOM and INDI programs such as N.I.N.A., SharpCap, FireCapture, Sequence Generator Pro, MaxIm DL and TheSkyX.
ASIAIR power tip: plug the EAFN into one of the ASIAIR's USB ports or your camera's USB hub. A USB-C to USB-C cable from the ASIAIR's USB-C port carries data only and won't power the focuser.
What to add for the best results
- ASIAIR Plus 256GB: the easiest way to run autofocus, with one tap in the app.
- ZWO EAF hand control: in and out buttons for focusing visually or without a computer.
- ZWO EAF temperature sensor: lets your software refocus automatically when the temperature drops.
- EAF bracket for C8 and C9.25, C11 and C14 or Takahashi (required for those telescopes): each includes the 4mm coupler the new EAF needs.
ZWO EAFN vs. EAF Pro
| EAFN | EAF Pro | |
|---|---|---|
| Connection | USB-C | USB-C and Bluetooth 5.0 |
| Power | Over USB-C | USB-C or built-in battery (about 7 nights) |
| Manual focus buttons | With optional hand control | Built in |
| Weight | 215g | 258g |
| Load capacity | 5kg (11lb) | 5kg (11lb) |
| Best for | Imaging rigs with a USB hub or ASIAIR | Wireless setups and visual observers who want buttons on the focuser |
See all ZWO EAF focusers and brackets.
What's in the box
- ZWO EAFN focuser body
- Standard mounting bracket
- 2m USB-C cable
- 3mm and 2mm hex wrenches
- Four flexible couplings in different sizes
- M5 and M4 screws and five spacers
- Quick guide
The hand control, temperature sensor and telescope-specific brackets are sold separately.
ZWO EAFN FAQ
Will the EAFN fit my telescope?
It fits most refractors and Newtonians with a Crayford or rack-and-pinion focuser using the included bracket and couplings. Celestron SCTs and Takahashi refractors need the matching bracket. If you're not sure, send us your telescope model and we'll tell you what you need.
Does it work with the ASIAIR?
Yes. Plug it into an ASIAIR USB port and it shows up in the app, where autofocus is one tap.
EAFN or EAF Pro?
Choose the EAFN if you image with an ASIAIR or laptop and a USB hub. The EAF Pro adds Bluetooth, a built-in battery and manual buttons, which help for wireless or visual use.
Can I reuse a bracket from an older EAF?
The new EAF uses a 4mm shaft coupler instead of the older 5mm one, because ZWO changed the internal motor. The brackets we stock include the 4mm coupler. If you have an older bracket, ask us before reusing it.
Can I use it for visual observing?
Yes. Add the EAF hand control to focus with buttons, which avoids shaking the view at high power.
Does it need its own power supply?
No. It draws 5V at 500mA over USB-C from a computer, camera hub or ASIAIR USB port.
Specifications
| Motor | |
|---|---|
| Type | Stepper motor, 7.5° step angle |
| Reduction ratio | 1:128 |
| Maximum focuser load | 5kg (11.02lb) |
| Connections and software | |
| Interface | USB-C (power and data) |
| Power | 5V, 500mA over USB-C |
| Accessory ports | Hand controller (3.5mm jack); temperature sensor |
| Software | ASIAIR, ASIStudio, ASCOM and INDI |
| Physical | |
| Dimensions | 41 x 52 x 70.3mm |
| Weight | 215g (7.6oz) |
| Shaft coupler | 4mm (new generation) |
| Warranty | 2 years (ZWO) |
| Model / SKU | ZWO-EAFN |