ZWO Duo-Band narrowband filter (2")

The ZWO Duo-Band Narrowband Filter (2") is actually a two-in-one filter, as it passes some wavelengths of light through two narrow bands while blocking other wavelengths.

This filter was designed specifically for ZWO's colour cameras. It makes it possible to take astrophotographs of emission nebulae in light-polluted urban conditions. The filter effectively blocks moonlight and light pollution, while providing 80 and 90% light transmission at Hα (656.3 nm) and OIII (500.7 nm) wavelengths.

The excellent choice of materials and machining precision that ZWO is known for are, of course, also a basic requirement for this product.