Coronado 15mm Blocking Filter

Coronado BF-15 right angle (1.25" diagonal) type secondary blocking filter. The blocking filter is the second element in any Coronado H-alpha system, and is just as crucial to your safety and the system's performance as the front element. Cannot be used without an SM front cell.

Secondary interference filter for full disc image of the Sun for telescopes up to 1,500mm focal length.