The BF-30 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 30mm blocking filter, the BF-30, is compatible with telescopes that have a focal length that is equal to or less than 3000mm. It features a 2.0" straight-through design, and a 1.25" zero-length reducer is included.
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.
Must be used with a SolarMax filter
Image size: 27.2 mm
2.0" straight-through design
1.25" zero-length reducer included
For telescopes with a focal length equal to or less than 3000 mm