Antlia CaK 3nm 393.3nm Filter 1.25"
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Vai al moduloAntlia CaK 3nm 393.3nm Filter 1.25" – Ultra-Narrow Band for Solar Imaging
The Antlia CaK 3nm filter is an ultra-narrow bandpass filter centered on the ionized Calcium II (CaK) line at 393.3nm, built on a heat-resistant, double-polished substrate with the most advanced multi-coatings. It is designed to maximize contrast for high-resolution imaging of sunspots, solar surface granulation and other features prominent in CaK light.
The high blocking specification – OD5 (0.001%) between 200 and 1200nm and OD3 (0.1%) between 1200 and 1500nm – delivers exceptional resolution for imaging. The CaK band (393nm) makes solar features almost invisible to the human eye due to low sensitivity and poor resolving ability at this frequency: the filter is therefore not recommended for visual observation, but designed for imaging with cameras whose spectral response goes well beyond human vision.
Warning: the CaK 3nm 393.3nm filter must be used exclusively in combination with a Herschel wedge. Never look at the sun with the CaK filter alone: even though you can't perceive it, a significant amount of harmful UV radiation can still reach the eye.
Key Features
- 3nm bandpass, centered on the Calcium K line at 393.3nm
- Heat-resistant substrate, double-polished
- OD5 (0.001%) blocking between 200–1200nm, OD3 (0.1%) between 1200–1500nm
- Advanced multi-coating for maximum contrast
- 1.25" mount (M28.5x0.6)
- For use only with a Herschel wedge
Technical Specifications
| Filter type | Ultra-narrow band CaK (Calcium II K) |
| Center wavelength | 393.3nm |
| Bandpass (FWHM) | 3nm |
| Out-of-band blocking | OD5 (0.001%) @ 200–1200nm; OD3 (0.1%) @ 1200–1500nm |
| Format | 1.25" (mounted, M28.5x0.6) |
| Substrate | Heat-resistant optical glass, double-polished |
| Intended use | Imaging only, exclusively with a Herschel wedge |
| Visual observation | Not recommended |
| Warranty | 3 years against delamination |