D-ERF 180mm Baader Energy Rejection Filter

Baader's energy absorbing filters transmit between 600 and 700nm, blocking the remaining visual range as well as the UV and IR range perfectly. Optically, it is made of perfect planar glass, so the imaging of the system is not degraded.

D-ERF Filters A component in the Hydrogen-Alpha telescope system that must be used separately when building your own telescope with a filter that is smaller than the objective.