ZWO EFW (8 x 1.25″/31mm or 7 x 36mm)


8 position filter wheel will be available aroound the middle of May.


Product Description

Our latest EFW (Electronic Filter Wheel), larger than the previous but still low on weight. Only 400 grams (14 oz)!


The body is CNC milled from an aircraft graded aluminum block.
We decided to make it thinner, where it measures only 20 mm on the wheel body.


The heart of our EFW comes from NPM, Japan, whose the manufactor for the stepmotor and the quality is trustful and reliable. Guaranteed long life.

dibuWe have two specifications:8*31mm and 7*36mm to select.

The Electronic Filter wheel can be rotated in both counter clockwise or clockwise direction for filter selection.



There are no need for multiple cables to power this wheel up, just one USB cable does the trick.The power consumption of this EFW is approximately 120mAh @ 5V, which can be operated from the Cooled CCD’s USB hub.


The distance between the filter and sensor is around 10mm when you connect it to ASI1600.

So 1.25″ filters won’t have vignetting up to F5 focal ratio scope and 31mm filter won’t have vignetting up to F2 lens.

Our new RGBL filters are recommended to work with ASI1600, it will offer nearly 1:1:1 RGB color balance.


What`s in the box?

  1. 8*31mm or 7*36mm EFW body
  2. 1.25″ Holder-T2
  3. T2 nosepiece
  4. Phillips screwdriver
  5. A bag of M2 screws
  6. T2-T2 adapter(male)
  7. USB2.0 cable



How to install the filter?

1.25″ filters required to be: threaded  shorter than 3mm in length,  without threads less than 7mm in height

  1. Take the back cover off
  2. Lay the wheel down flat
  3. Screw-in the filters up
  4. Put the back cover on

Take the EFWmini for an example:


31mm and 36mm filter requires: a set of M2 screws and washers needed to fix the filters are included in the package .

  1. Take the back cover off. Lay the wheel down flat
  2. Hold the filter by the very edges and lay them in to the recess for each position
  3. Attach the washers,put in the screws
  4. Put the back cover on

Take the EFWmini for an example:


How to connect with the camera and telescope?


How to use it?

you just need to plugin the EFW with USB2.0 cable and install the   ASCOM driver

There are  ZWO Filter Wheel(1) and ZWO Filter Wheel(2) to select,  you can use either one of them

There are 2 ASCOM is for controling 2 EFW in one software.

Mechanical drawing



  • Fast shipping: we will choose DHL, UPS, TNT, EMS etc to deliver it. Usually you will get your package in one week. We provide free fast shipping for order above $300 or charge extra $20 for order below $300.
  • Free air mail shipping: we will ship via DGM or China Post Registered Air Mail. It usually costs 2-3 weeks to reach US or Europe and costs 3-4 weeks to reach far places.
  • Customers from Brazil and Chile should leave a message to provide your CPF or CNPJ as your custom needs it.
  • Customers from Russia need to provide the name of your company.

Tracking site:


China air mail:


  • The price list on our website is USD without tax.
  • Please note that buyers areliable to pay tax involved, such as Import tax, VAT , customs handling fee, etc. The additional fees may be collected at time of delivery by courier.
  • For best local service we advise customers buy our cameras form local dealers.

Warranty and Return Policy

  • We provide 2-year warranty for our products, we will offer the repair service for free or replace for free if the camera doesn’t work within warranty period. After the warranty period, we will continue to provide repair support and service on a charged basis.
  • This warranty does not apply to damage that occurred as a result of abuse or misuse, or caused by a fall or any other transportation failures after purchase.
  • Customer must pay for shipping when shipping the camera back for repair or replacement
  • If you get a faulty camera, please contact us as soon as possible though email: Please describe the problem in detail and we will do our best to help you solve the problem. Most instances perceived problems are simply bad driver install or software configuration.
  • For customers who bought the camera from our dealer, dealer is responsible for the customer service for you.

Do you have uestion, answer or comment? Post here!

  1. :

    Will you sell an EFW+OAG package soon?

    • Sam Wen


      OAG will be ready at this month

  2. :

    Will this be offered in a kit? I am interested in the ASI1600MM-cool kit but would like this EFW instead of the EFWmini.

    • Sam Wen


      yes, the kit will come

  3. :

    Will the filter carousel be available separately? If I purchase the 8×1.25″ version as a started, is it possible to purchase only the carousel if I should upgrade to 36mm filters?

    • Sam Wen


      of course, the 36mm filter will be provide separately

  4. :

    Looks very interested.
    1. How thick will this new Filter wheel be?
    2. How much back focus will it take up?
    3. Will there be an ASCOM driver available when it is released?
    4. T-Threads front male? back female?

    • Sam Wen


      1. still 20mm
      2. 20mm
      3. yes, the same one with EFWmini
      4. yes, T2 in both side

  5. :

    Whether the order for aliexpress will be available?

    • Sam Wen


      need to wait to next year, there is some problem with aliexpress platform

  6. :

    Will the zwo EOS adapter for mini EFW work with this new filter wheel as well?

    • Sam Wen



  7. :

    Can you give us the dimensions? How thick is it? I am concerned about my total back focus.

    Are you currently developing an OAG to pair with the FW and 1600? If so, is there a time frame for release?


    • Sam Wen


      20mm thick, our OAG will pair with EFW and 1600 and in 55mm back focus distance

  8. :


    Thanks for the response. Really curious to when the OAG will start shipping? I am eager to buy all three OAG/FW/1600. but can’t buy any until they are all available for sale!

    Thanks again,

    • Sam Wen


      I am sure our OAG will be available in end of this month

  9. :

    What is the thickest filter cell this FW will accept (not counting the threaded length)?

  10. :

    Sorry, I missed the information in the description. So it seems like some older Astrodon filters may not fit into these filter wheels due to there excessive height (my Astrodon 6nm Ha measures 8mm thick without thread).

    • Sam Wen


      that’s bad news

  11. (verified owner):

    How thick will be the new OAG?

    • Sam Wen



  12. :

    This product is already available to purchase?

    • Sam Wen


      yes, it’s instock

  13. (verified owner):

    Thickness of EFWmini and EFW 8 x 1.25 identical?

    • Sam Wen


      yes, 20mm

  14. :

    The thickness is reported, but what is the height and width (e.g. The diameter of the wheel) of the EFW (NOT the Mini). Also will it accommodate 7 x 36mm unmounted Astrodon filters which are thicker than most?

    • Sam Wen


      we will upload the diameters soon, you can use unmounted filters
      we use screw to fix their position

  15. :

    Is there going to be 2″ version any time soon?

    • Sam Wen


      I don’t think very soon
      but we will release when there is new ASI camera need 2″ filters

  16. :

    The description says the 1.25″ filter won’t have vignetting to f/5 and 31mm won’t have vignetting to f/2. Since 1.25″ = 31.75mm I am wondering if this is a typo error? Perhaps it should have said 36mm won’t have vignetting to f/2. Is this a correct assumption?

    • Sam Wen


      this is the vignetting working with our ASI1600 cameras

  17. :

    Sam, You may disregard my question above. I have since learned that a 1.25″ filter is actually only 28mm diameter of usable filter (not simply a conversion from inches to mm), so that explains my confusion.

    • Sam Wen


      usually 26mm diameter actually
      31mm filter have 28mm diameter usable filter

  18. :

    I already have LRVBHaO3S2 astrodon filter in 36mm.Do they be ok with the EFM 7position ? When the OAG will be aviable ? you say befor it arrivend curent novebre 2016 ?? Also the package OAG/FW/1600MMC ? Sicnerly.

  19. :

    Will this filter wheel work with a Mac OS program like Nebulosity?

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