What is the purpose of the Lunt B600 Blocking Filter?
The Lunt B600 is a required safety component for any Lunt Solar Systems H-alpha etalon. It contains a series of secondary filters that block harmful radiation and heat, while also enhancing the contrast of solar features. It is not an optional accessory; your Lunt etalon will not perform correctly or safely without it.
Can I use the Lunt B600 Blocking Filter with a non-Lunt etalon?
No. Lunt blocking filters are designed as part of an integrated system. Lunt only warranties the safety and performance of their products when their etalons are paired with a corresponding Lunt blocking filter. Using it with other systems is not recommended and can be unsafe.
Should I get the B600 or B1200 for my Lunt LS50THa telescope?
For purely visual use with the Lunt LS50THa, the B600 is perfectly adequate and will show the full solar disk. However, if you plan to do any imaging, it is strongly recommended to choose the larger B1200 to prevent vignetting (darkening at the corners of your image) due to the extra back focus required by a camera.
Why is a larger blocking filter like the B1200 recommended for imaging with my 80mm f/7 refractor?
An 80mm f/7 refractor has a 560mm focal length. While the B600 is suitable for visual use at this focal length, imaging setups require more back focus. This means your camera sensor sits farther back from the telescope than an eyepiece, intersecting a wider part of the light cone. The larger aperture of a B1200 ensures this wider cone passes through to the sensor without being clipped, preserving brightness across the entire field.
What is the difference between the diagonal and straight-through versions of the Lunt B600?
The choice depends on your application:
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Star Diagonal (1.25" or 2"): This is the standard choice for visual observing, as it places the eyepiece at a comfortable 90-degree angle.
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Straight-Through (2"): This version is preferred for imaging, as it provides a direct light path to the camera sensor with fewer optical surfaces and potential for flexure.
Does the Lunt B600 come with T2 threads?
Yes, all available housing options for the Lunt B600 blocking filter—the 1.25" diagonal, 2" diagonal, and 2" straight-through tube—come equipped with a male T2 thread connection. This allows for a secure, threaded attachment to most standard astronomy cameras and T-rings.
