LUNT Blocking Filter B400 - 1.25" Star Diagonal (OPEN BOX)

In Stock
SKU: OPENBOX022003
Regular price $349.00 CAD

Product details

  • SKU OPENBOX022003

Blocking filter will be mounted at the eyepiece side of the telescope, block unwanted wavelengths and thus protect against the dangerous radiation from the sun.


For telescopes up to 400 mm focal length

Cannot be used individually, only with an H-alpha filter system or H-alpha telescope from Lunt! Without the etalon filter present there, H-alpha observation of the sun is not possible because the bandwidth is too wide.

Lunt Solar Systems currently offers different blocking filter apertures for use with their H-alpha etalon systems. The blocking filters are absolutely required for the safety and performance of telescopes for solar observing! Blocking filters will be mounted at the eyepiece-side of the telescope, and protect against the dangerous radiation from the sun.


The Blocking Filter B400 is for maximum focal length 400 mm, B600 is for 600 mm, B1200 is for 1200 mm, B1800 is for 1800 mm and the B3400 is for 3400 mm maximum focal length. This is the focal length of telescope for which that particular blocking filter will provide a full disk image of the Sun. A blocking filter larger than that required might be needed for imaging.

Lunt Solar Systems blocking filters contain a unique filter system. We can only warranty safety or performance if the blocking filter is paired with an original H-alpha front filter of Lunt Solar Systems.

Important hint: In humid air, blocking filters might tarnish, so keep yours dry. You can get little packages of silica gel for reducing humidity even more. Put one and the filter into a small freezer bag and seal it.