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LUNT B1800s Blocking-Filter in extension tube

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LUNT B1800s Blocking-Filter in extension tube

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LUNT B1800s Blocking-Filter in extension tube

Blocking-filter in straight extension tube, for telescopes up to 1620mm focal length. Can only be used together with a LUNT H-alpha filter, or with a LUNT H-alpha telescope!

Lunt Solar Systems offers blocking-filters in different sizes, and alternatively in 90° star-diagonal housings or straight extension tubes. You can choose what blocking-filter you will use at your LUNT H-alpha Etalon system.

The B1800s is installed in a straight extension tube, for 1.25" and 2" focuser on the telescope side, and with T2 thread and 1.25" eyepiece connection on the eyepiece side. The B1800s can be used at LUNT H-alpha systems, if the used telescope has up to 1620mm focal length.

The blocking-filter can not be used without additional H-alpha filter system from Lunt Solar Systems! Blocking-filters are absolutely required for the safety and performance of H-alpha telescopes for solar observing. Lunt Solar Systems blocking-filters contain a unique filter system. We can only warranty safety or performance, if blocking-filter is paired with a H-alpha filter or H-alpha telescope of Lunt Solar Systems.


  • Blocking-filter only usable at additional H-alpha filter system
  • Filter diameter: 18mm
  • Usable at telescopes up to 1620mm focal
  • In straight extension tube
  • For 1.25" and 2" focuser
  • Connection for 1.25" eyepieces
  • T2 thread for camera connection


  • Blocking-filter B1800s in straight extension tube