EOS Lens Adapter for EFW


SKU: ZWO-EFW-EOS Category:

Product Description

The Short EOS adapter for EFW&Cooled camera(6.5mm backfocus version).

Extend distance: 17.5mm


So you can use Canon Lens with ASI1600 and EFW



Before first usage of this product read manuals and install correct drivers and software.


  • Fast Shipping(amount ≧ 299USD) for free
  • Fast Shipping(amount < 299USD) : $20.00
  • Free Shipping(amount < 299USD) (Air Mail, 3-4 weeks) (Free)


  1. 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 ≧ $299 or charge extra $20 for order < $299.
  2. Free 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.
  3. Customers from Brazil and Chile should leave a message to provide your CPF or CNPJ as your custom needs it.
  4. Customers from Russia need to provide the name of your company.

Tracking site:

DGM: http://webtrack.dhlglobalmail.com/?locale=en-US

China air mail: http://www.17track.net/en


  • 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: info@zwoptical.com. 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. :

    What is the back focus spacing on this thinner adapter?

    • Sam Wen


      this is designed for 1600 and our EFW especially
      so the back focus is 6.5+20=26.5mm

  2. :

    I am buying the 1600mm cooled camera. I have a 1150mm f4.5 Newtonian telescope. Am I likely to need a coma corrector with this setup?

    • Sam Wen


      yes, you need coma corrector for 4/3″ format camera

  3. :

    I have a 25mm 7-position filter wheel I would like to use with the 1600. The camera is 6.5mm. So, 6.5mm + 25mm + EOS adapter = ??
    Will this work? Or, are you coming out with a 7-position 20mm filter wheel sometime? What is the back spacing of the EOS adapter? Thanks.

    • Sam Wen


      the back space of the EOS adapter is 44-26.5=17.5mm
      so you cannot use our EOS adapter with your filter wheel
      yes there will come a big EFW with 7 or 8 1.25″ filters

  4. :

    I have a QHYFW2-M-US and one directly connected to the ASI1600MM the back focus appears to be 26.25mm. What is the back focus tolerarnce? Is off-by 0.25mm going to be a problem?

    What type of connector does the adapter use to connect to the filter wheel?
    (i.e. T-thread, male or female etc).


    • Sam Wen


      the back focus tolerance should be 0.5mm
      so 26.25 should be ok

      the connector to connect EFW is T2 male

  5. :

    I’m an happy owner of ASI1600 MC-C, is it available a similar adapter for Pentax lenses?

    • Sam Wen


      maybe you can use Pentax to EOS adapter

  6. :

    Do you sell spacers to get to 44mm of back focus. I want to use this adapter on your color CMOS so don’t need a filter wheel.

  7. :

    I own an ASI 178mm camera, and an ASI manual filter wheel.
    From what I read, the adapter for “all ASI cameras” has not enough backfocus for filter wheel use, will this one be ok instead, even if it says it’s for 1600?

  8. :

    it’s 44-20-6.5=17.5mm

  9. :

    That should have said what is the thickness of this adapter please. Also will it work with your manual filter wheel.

  10. :

    What is the recommended maximum lens weight when an ASI 1600 camera is screwed to a tripod using the new holder ring for ASI cooled cameras and using the ZWO 8×1.25 EFW? Can it suppor the Samyang 135mm f/2 lens (830g)?

    • Sam Wen


      I think it’s better to use 2 rings and one dovetail
      SamYang 135 F2 is too long

  11. :

    The photo shows only a female thread. Does it come with an adapter that gives a male T2 thread? I don’t have the EFW yet, it is in my upgrade list, but I was wondering whether I could get this part now and use it with my old 1.25″ nosepiece camera (I have a T-thread to 1.25″, but it needs a male T-thread to screw on). Thanks!

  12. :

    I am a very happy owner of the ZWO 1600 cooled monochrome. I have taken fantastic picture with my SCT 8″. I would like to take wide angle images of the sky with narrow band filters. I have the orion 5-position filter. It is manual. Will the back focus allow for this filter and the lens of Canon Rebel 450 to attach to my ZWO ? How thick is your EFW ?

    • Sam Wen


      our EFW is 20mm thickness
      ypu’d better pick up our EFWmini

  13. :

    Is it possible to use an EOS lens with the 1600mm+efw mini+Lps filters? I have a 2″ filter but not sure where it would go in the train with the EOS lens

    • Sam Wen


      seems it’s not possible
      maybe you can get the 2″ filter glass out and put it into the EOS adapter?

  14. :

    Is EOS Lens Adapter for EFW threaded for 2″ filters as well so it can accommodate an LP filter?

    • Sam Wen


      no, there is no space for 2″ filter

  15. :

    I have the EOS-T2 adapter but the mounting ring is too thick for my filter wheel. The mounting ring on the back of this adapter is thin and would work with my filter wheel. Could I order just the mounting ring (59mm female to T thread male) only?

    • Sam Wen


      sorry, this adapter is only used for our EFW and 1600
      the thickness of our M59 female to T thread male is not correct for you

  16. :

    I have ASI1600MM-C+EFW so I know this adapter will work to have Canon EF lens. I also have ASI290MC. Can I use this adapter with spacers on my ASI290MC? I do not want to buy two EF adapters if I can use the short one with spacers (I have many extra spacers of various length).

    • Sam Wen


      you can add one spacer to make the EOS adapter works on 290MC

  17. :

    Hi Sam
    I have the ASI 1600MM cool and mini EFW.
    I have been using the EOS adapter to connect to the Canon adapter on my telescope.
    But the EOS Adapter has developed some play (about 1mm) between the EOS adapter and the Canon adapter.
    This means the camera is not aligned properly anymore as the EOS adapter is not tight to the Canon adapter on the top side.
    The weight of the ASI 1600 is pulling the gap open.
    Is there away to remove this slackness from in-between the two adapters?
    Has this been reported before?
    If I cannot remove the play that now exists I will have to use a solid connection between Mini EFW and scope.

    • Sam Wen


      you should use some solid connection between EFW and scope
      EOS adapter is not tight enough

  18. :

    I have an ASI 1600MM-Cool and the 8-slot filter wheel with 31mm filters. Will this adapter work for all types of Canon lenses with that combination? I am planning on using it with my Canon 300/4L tele lens.

    • Sean Wang


      EOS Lens Adapter for EFW & 1600 will be perfectly match! :)

  19. :

    When will this adaptor be available?

  20. :

    Will this be stocked again any time soon?

    • Sam Wen


      yes, just waiting another one or 2 weeks

  21. :

    Hi Sam,
    any news/update about the availability?

    • Sam Wen


      we have it instock now

  22. :

    Hey Sam – I second Stefan’s question. I’ve had one on order for a month now and I’m unable to use my new ASI1600 Pro until I can get one of these adapters.

    • Sam Wen


      you can order on line now

  23. :

    Hi, Sam. I recently bought ASI 1600 Pro with EFW, it is an amazing camera, great thanks! I am thinking to use the camera with my Canon EF-S lenses. My questions: 1.when you will have the EFW adapter in stock (the site shows out of stock)? 2. does this adapter work with both EF and EF-S Canon lenses? 3. Does holder ring (78 mm) properly fits ASI 1600?

  24. :

    Hello, Sam, any updates?

    • Sam Wen


      you can put order now

  25. (verified owner):

    Great thanks, Sam, I did.

  26. :

    I have the ASI178MM-Cool and the 8 position EFW, I’d like to attach a 50mm f1.8 or a Samyang 135 F2 to the filter wheel and camera, would this adapter be comparable with this setup for wide-field work?

  27. :

    My apologies if this has already been answered – I’m considering buying the ASI1600MM Pro (6.5mm) with 8 position EFW (33mm) on a Canon lens (55mm requirement), but this adapter is 17.5mm, which makes it 2mm too deep? Is there a Canon adapter of 15.5mm depth, or have got my sums wrong?

    • Sam Wen


      our EFW is 20mm thick, 6.5+20+17.5=43.5 which is very close to Canon back focus distance

Add new