The Svbony SV220 Duo-Band (1.25") Narrowband Filter makes the work of astrophotographers using colour cameras in light-polluted urban environments easier. It transmits light only in two very narrow bands while blocking other wavelengths.
The Svbony SV220 Duo-Band (1.25") Narrowband Filter offers 90% and 94% light transmission at the Hα (656.3 nm) and OIII (500.7 nm) wavelengths, which are emitted by emission nebulae. It effectively blocks moonlight and light pollution.
The filter comes in a practical protective case. It is not recommended for telescopes with an f-ratio faster than f/4.