by Chuck’s Astrophotography 2017.5.24 SUBSCRIBE SUBSCRIBED UNSUBSCRIBE This is my new ZWO 8-position electronic filter Wheel (EFW). This filter wheel supports the 1.25″/31mm size. I bought this because I was tired of having to swap out broadband and narrowband filters when I used the 5 position filter wheel. An EFW is a must for astrophotography.