Antlia Solar Discover solar filter - CaK 5Å version - Filter only

Antlia Solar Discover solar filter - CaK 5Å version - Filter only (2" / 50.8 mm and 1.25" / 31.8 mm barrels).

The Antlia Solar Discover CaK 5Å solar filter has been designed to maximize the contrast of images of so-called plages, faculae, sunspots, and other features that are particularly evident in Calcium K (CaK) light at 393.3 nm when using very narrow passband filters.

Antlia's 5Å ultra-narrow bandpass filter is incorporated and has a 12-mm aperture and a wavelength centered on the Calcium K-line at 393.3 nm. With its ultra narrow bandwidth (FWHM) of 5Å, it enables the capture of chromosphere details.

The filter body is made of billet aeronautical aluminum and machined with high-precision numerically controlled (CNC) machinery.

The filter is designed to work at the focus of a refracting telescope with a focal ratio of at least F/7. Dedicated 2x, 3x and 5x Barlow lenses are optionally available for use with this filter and are also available for purchase preinstalled with the filter.

If the telescope has a built-in corrector near the focus, then an rejection filter (ERF) is required to be placed in front of the objective. If it is a refractor with a classic doublet or triplet design, then up to 100 mm the ERF filter built into the Solar Discover is sufficient. If, however, you want to use a diagonal mirror, consider an additional ERF in a 2" filter holder cell, sold separately and to be placed before the diagonal mirror. The use of diagonal prisms is not recommended. Beyond an aperture of 100 mm, a full-aperture rejection filter becomes necessary, or you must diaphragm the objective.

Please note: the additional ERF, if any, must also let through the lines of Calcium H @ 396.8 nm and Calcium K @ 393.3 nm, as well as the line of H-alpha @ 656.3 nm. The rejection filters optionally offered by Antlia Filter meet this requirement.

The CaK 5Å version is equipped with double barrel for 2" / 50.8 mm and 1.25" / 31.8 mm eyepiece holders.

Visual observation

Unfortunately, the Calcium K line (393.3 nm) is nearly invisible to the human eye, so the Antlia Solar Discover 3 nm CaK solar filter is used primarily for solar imaging and is not recommended for visual observation.

Please also note that the infrared filtering of these Antlia Solar Discover solar filters differ slightly from the ISO 12312-2 standard for solar viewers; please see the table below and refer to the ISO 12312-2 standard for solar viewers (https://eclipse.aas.org/eye-safety/iso12312-2).

Due to stringent technical requirements and safety considerations, we do not recommend these filters for visual observation. If you really want to use the product for visual observation, it is important to make sure that all filters built into the product are in perfect integrity. We recommend that you contact us directly for further information.

Warranty

The product warranty is 3 years.

Please note: disassembling the filter is prohibited and voids the warranty. Any repair/replacement/exchange
for this item cannot be accepted should disassembly be determined.