The BF-10 Blocking Filter from Coronado is the secondary interference filter in a Coronado H-Alpha solar viewing system. Blocking filters are not stand-alone devices; they must be used in conjunction with a SolarMax filter. In a solar viewing system, the blocking filter is just as crucial to the viewer's safety and the system's performance as the front element. This 10mm blocking filter, the BF-10, is compatible with telescopes that have a focal length that is equal to or less than 1000mm.
Note: SolarMax filters are sold in kits that include a blocking filter. This blocking filter offered here is intended for viewers who have two different focal length telescopes that they intend to use with their SolarMax system.