About this product

Coronado SolarMax III Blocking Filter BF15

The Coronado BF15 15mm right angle (diagonal) type Hydrogen-alpha blocking filter, now in the SolarMax III design!

This updated design includes a long 2″ diameter nosepiece with a 1.25″ eyepiece holder and a T-thread connection. 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 primary SolarMax etalon filter. This secondary interference filter provides a full disc image of the Sun for telescopes up to 1,500mm focal length. It can also be used with 1.25″ focusers by purchasing the Coronado 1.25″ adapter #624018. 

NOTE: This blocking filter CANNOT be used itself without a SolarMax etalon in front of the telescope front aperture. 

The BF15 is named because of the 15mm clear aperture window that passes the hydrogen-alpha light to the eyepiece or camera sensor. This 15mm window is wider than the window in the BF10 and thus provides a wider unvignetted field of view around the sun. This will allow wider apparent field of view eyepieces, higher magnification, and larger camera sensors to see an unvignetted view compared with the BF10 version.

Designed and Manufactured in North America.

Features

• Hydrogen-alpha blocking filter for Coronado primary etalon filters
• Secondary interference filter for full disc image of the Sun for telescopes up to 1,500mm focal length
• Long 2″ diameter nosepiece with 1.25″ eyepiece holder and t-thread
• 15mm clear aperture provides a wider unvignetted field of view compared with the smaller BF10 filter