Coronado BF30 (straight through) type secondary blocking filter. The blocking filter is the second element in any Coronado H-alpha system and 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 with 30mm clear aperture, optimized to minimizing vignetting in applications such as full disc imaging of the Sun using DLSR or similar cameras on telescopes up to 3,000mm focal length. Features precision machined 2" barrel diameter and includes 1.25” adapter and 1.25” (non-blocking) diagonal in a carry case. Requires 2" focuser.