Antlia 4.5nm H-Alpha Edge Series Filter - 31 mm - HA-EDGE-4.5NM-31 Focusers While this filter is similar

While this filter is similar to the D1 duo-narrowband filter

This anodized black 21mm extender can help you reach the proper focusing distance for your set-up

the iOptron #3324 Counterweight Balance Kit

37mm) allowing for faster installation

but also three accessories (reducer

Antlia 4.5nm H-Alpha Edge Series Filter - 31 mm - HA-EDGE-4.5NM-31 Focusers While this filter is similarThis narrowband 4. 5 nm H alpha filter from Antlia is part of their Edge series and is of the 31 mm unmounted variety. It is normally used in a 1. 25" 31mm filter wheel, where it drops into place. Important! Not for use when viewing or imaging the Sun! Antlia 4. 5nm Edge Series H Alpha Filter 31 mm Unmounted Antlia H alpha Edge narrowband filters optimize the FWHM (full width half maximum) to a 4. 5nm bandpass. The suppression of optical density (OD)5