Antlia Solar Discover solar filter - CaK 3 nm version

Antlia Solar Discover solar filter - CaK 3 nm version (2" / 50.8 mm)

The Antlia Solar Discover 3 nm CaK filter is designed to maximize the contrast of sunspot images, solar surface granulation and other features that are particularly evident in Calcium K (CaK) light at 393.3 nm.

An Antlia 3 nm FWHM (bandpass filter) with wavelength centered on the Calcium K line at 393.3 nm is integrated. Its blocking specifications are very high (OD5 0.001%), and it enables the reduction of most of the harmful frequencies and excess heat.

The product is equipped with an Antlia ERF (Energy Rejection Filter), which cuts harmful UV and IR frequencies, allowing the desired wavelengths (H-alpha @ 656.3 nm, Calcium K @ 393.3 nm and Calcium H 396.8 nm) to pass through. In addition, an ND filter, necessary to attenuate excess light, is already installed inside the filter body.

Compared with the Herschel prism, the Antlia Solar Discover CaK 3 nm filter has a new design, 1.25'' and 2'' adapters were considered, and light-reducing filters were added. The installation is similar to that of the Herschel Antlia CaK 3 nm prism. The filter body is made of billet aircraft aluminum and machined with high-precision numerically controlled (CNC) machinery.

The filter is designed to work at the focus of a refracting telescope. 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.

CaK 3 nm version, for 2" / 50.8 mm eyepiece holders with adapter included for 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.