Lunt Calcium K Blocking Filter Module
See The Sun In Calcium K Light
This calcium K blocking module from Lunt works at 393.4 nm, the calcium K line at the violet edge of the visible spectrum. It shows a lower, cooler layer than hydrogen alpha, where supergranulation cells and bright plage trace the magnetic network. Running CaK alongside H-alpha tells you more about the structure and depth of active regions.
Treat CaK as a photographic wavelength. Most adult eyes respond poorly at 393 nm because the cornea and lens yellow with age, so many observers see the violet colour but little contrast. Observers who have had cataract surgery often see far more. A camera records the detail readily, which is why the module is built around imaging.
The module carries internal narrowband filters for a bandpass under 2.4 Angstrom and mounts on most standard night time refractors, or on a Lunt modular telescope in its night configuration. Pick the blocking aperture by focal length: B600 to 600 mm, B1200 to 1200 mm and B1800 to 1800 mm, each rated for apertures up to 100 mm.
Key Features
- Calcium K Line - centred on 393.4 nm, a lower and cooler layer than the hydrogen alpha chromosphere
- Narrow Bandpass - internal narrowband filters give less than 2.4 Angstrom
- Imaging First - most adult eyes respond poorly at 393 nm, so a camera is the usual detector
- Three Apertures - 6 mm, 12 mm and 18 mm modules cover focal lengths to 600, 1200 and 1800 mm
- Housing Choice - each aperture comes as a 2 inch star diagonal or a 2 inch straight through tube
- Wide Compatibility - fits most standard night time refractors and Lunt modular telescopes in night configuration
| Specifications | |
|---|---|
| Type | Calcium K blocking filter module |
| Wavelength | 393.4 nm, the calcium K line |
| Bandpass | Less than 2.4 Angstrom |
| Primary Use | Imaging, since most adult eyes respond poorly at 393 nm |
| 6 mm Diagonal Module | 2 inch star diagonal, telescopes to 100 mm aperture and 600 mm focal length |
| 6 mm Straight Module | 2 inch straight through tube, same aperture and focal length rating |
| 12 mm Diagonal Module | 2 inch star diagonal, telescopes to 100 mm aperture and 1200 mm focal length |
| 12 mm Straight Module | 2 inch straight through tube, same aperture and focal length rating |
| 18 mm Diagonal Module | 2 inch star diagonal, telescopes to 100 mm aperture and 1800 mm focal length |
| 18 mm Straight Module | 2 inch straight through tube, listed on the storefront as LS18CaKMDs2 |
| 130 mm Module | Listed as the 130mm Universal CaK Module, storefront SKU LSCaKMD, published as a single option |
| Telescope Aperture Limit | Up to 100 mm for the 2 inch modules |
| Compatibility | Most standard night time refractors and Lunt modular telescopes in night configuration |
| Model / SKU | LS6CaKMDd, LS6CaKMDs, LS12CaKMDd, LS12CaKMDs, LS18CaKMDd, LS18CaKMDs and LS130TCaKMD |
| Storefront SKU Format | LS6CaKMD, LS12CaKMD, LS18CaKMD, LS6CaKMDs, LS12CaKMDs, LS18CaKMDs2 and LSCaKMD |
| Shipping Weight | 2 lb for the 2 inch modules, 4 lb for the 130 mm module |
| Warranty | 5 years from date of purchase, original purchaser, manufacturing and workmanship defects |
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