Why is the Lunt B1200 CaK filter recommended for imaging over visual use?
The Calcium K line is at 393.4 nm, a deep violet color at the edge of the visible spectrum. Many people have difficulty seeing fine details at this wavelength due to natural aging of the eye. Cameras are far more sensitive to this light, allowing them to capture high-contrast details like supergranulation that are often invisible to the eye.
What solar features does the Lunt B1200 CaK filter show that H-alpha filters do not?
The Lunt B1200 CaK filter shows a different, lower, and cooler layer of the chromosphere. It excels at revealing the "cobblestone" pattern of supergranulation cells across the solar surface, which are particularly bright and defined around sunspots and active regions. H-alpha, in contrast, is better for viewing prominences, filaments, and details in the upper chromosphere.
Can I use the Lunt B1200 CaK module with my 100mm f/7 refractor?
Yes. The Lunt B1200 CaK module is designed to work with most standard nighttime refractors. A 100mm f/7 refractor is an excellent choice for this filter, providing enough aperture to resolve fine details within the Ca-K line. The 12mm blocking filter is well-matched to the focal length, ensuring the full solar disk is illuminated on your camera sensor.
What is the difference between the diagonal and straight-thru versions of the B1200 CaK filter?
The choice depends on your ergonomic preference and imaging setup.
- The 2" star diagonal version places your camera at a 90-degree angle, which can be more comfortable and may help with clearance issues on certain mounts.
- The 2" straight-thru tube version keeps the camera directly in line with the telescope, providing a straight optical path which some imagers prefer for simplicity and alignment.
Both versions contain the same B1200 CaK filter and offer a T2 thread for camera connection.
Will I see more detail with the Lunt B1200 CaK if I've had cataract surgery?
It is often reported that individuals who have had cataract surgery can see significantly more detail in the Ca-K line. The surgery replaces the eye's natural lens, which may have yellowed with age, with a clear artificial lens that transmits more of the violet 393.4 nm light. However, even with this advantage, imaging is still the recommended method for capturing the full range of detail.
How does the Lunt B1200 CaK filter help in studying a complex sunspot region?
While white light filters show the dark umbra of a sunspot, the Lunt B1200 CaK filter reveals the associated magnetic activity in the chromosphere above it. You will be able to image the bright, magnetically-contained plasma (plage) surrounding the sunspot, providing context and showing the extent of the active region that is invisible in white light or even H-alpha.
