Astronomy Specialist

ZWO EFW 5 x 2" / 7 x 2"


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ZWO developed two filter wheels for 2" filters. Cameras with large sensors such as the ASI 6200 require 2" filter to avoid any vignetting.

These electronic filter wheels are CNC machined and they have an optical thickness of only 20mm.

There are two models available:

  • type 1: 5 filters x 2″ mounted 
  • type 2: 7 filters x 2" mounted

The power absorption of the EFW is only 120mAh @ 5V so any USB cable can power it up. The distance between the filter and sensor of the ASI 6200 is only 18 mm. 

Unmounted filters with a diameter of 50.4mm ± 0.5mm can be used in both filter wheels. 

Mounted filters from third-parties producers can be used but they have to meet the following requirements:


    Compatible filters 5 x 2" mounted / 7 x 2" mounted
    Power draw 120 mA @ 5A
    Power supply USB cable
    Maximum thickness of the filter 7.5 mm (not including threads which must be less than 2.7 mm)
    Optical thickness 20 mm
    Camera connection
    Direct screw connection to camera with tilt plate removed, M54 x 0.75
    Telescope connection M54 x 0.75 female
    Camera compatibility APS-C and larger ASI cooled cameras or cameras with a male M54 x 0.75 thread or compatible tilt plate
    SKU ZWO-EFW-5x2, ZWO-EFW-7x2






    55mm backfocus with 4/3" or 1" cooled cameras with T-2 Tilter 



    55mm backfocus with 4/3" or 1" cooled cameras with T-2 Tilter and OAG 



    55mm backfocus with APS-C cooled camera and standard OAG



    55mm backfocus with full frame cooled camera and OAG-L



    55mm backfocus with full frame cameras and no off-axis guider


    Click here for detailed instructions for removing the sensor tilt plate and alternative setups.

    Customer Reviews

    Based on 1 review
    marius van

    First tried the QHYCFW3, but could not get it working even after getting tech support and was returned as a dead on arrival unit. Very glad with this unit however as the ZWO is plug and play, uses 1/4 of the power so can be powered of any USB port and just works.

    Welcome Newcomer