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Orion Telescopes
Coronado SolarMax III Blocking Filter BF15
3 easy payments of $283.33
With payment plan
Accepted Payment
Expected Ship Date: 01/05/2024

  • 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
  • MUST be used in conjunction with a front etalon filter - cannot be used alone

Learn more
Item #  55896b
Mfg Model #  624016

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 1.25" eyepiece holder and 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. Note this blocking filter CANNOT be used by itself without a SolarMax etalon in front of the telescope front aperture. This secondary interference filter provides a full disc image of the Sun for telescopes up to 1,500mm focal length. Can also be used with 1.25" focusers by purchasing the Coronado 1.25" adapter #624018.

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.

Product Support
Visit our product support section for instruction manuals and more

Blocking Filter
SMIII 70mm instruction manual

Orders received by 1pm Eastern Standard Time for in-stock items ship the same business day. Order received after noon will ship the next business day. When an item is not in-stock we will ship it as soon as it becomes available. Typically in-stock items will ship first and backordered items will follow as soon as they are available. You have the option in check out to request that your order ship complete, if you'd prefer.


This product is available to ship Standard delivery US except for delivery to Alaska and Hawaii. Delivery is available to APO/DPO/FPO addresses. Delivery is not available to US territories/protectorates. Delivery is available to Canada.

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