Antlia Solar Discover 3nm CaK Filter Assembly

3nm CaK Imaging at 393.3nm for Maximum Contrast

By targeting the specific 393.3nm wavelength of the Calcium II K-line, this assembly reveals a different layer of the sun's atmosphere than white-light or H-alpha filters. The ultra-narrow 3nm bandpass is designed to maximize imaging contrast of solar surface granulation, sunspots and other features prominent in CaK light, such as bright faculae near the solar limb.

OD5 Blocking and the 100mm Refractor Aperture Limit

The built-in 3nm CaK filter has a high blocking specification of OD5 (0.001%), intended to reduce most solar heat ingress, and the assembly adds one set of light-reducing filters. Without an extra light reduction solution, Antlia says the Solar Discover 3nm CaK can only be used with refractors up to 100mm aperture. With any telescope above 100mm aperture, Antlia requires additional light reduction for safe operation, such as ERF filters, solar safety films, or lowering the telescope aperture.

• Enclosed Optical Path: The filters are housed in a fully closed tube, so no stray light can escape.
• Zenith Mirror Use: When you use a zenith mirror, the ERF filter must be installed in the correct position for safe operation. Follow Antlia's installation diagram.
• Disassembly Prohibited: Disassembling the assembly is prohibited and voids the 3-year warranty. Repairs, returns and exchanges are not accepted once it has been disassembled.

CNC-Machined Housing with 1.25" and 2" Adapters

The assembly is built into a metal tube CNC-machined from aircraft aluminum and oxidized. Installation is similar to the Antlia CaK 3nm Solar Herschel Wedge: the telescope attaches to one end and your camera to the other. Antlia designed 1.25'' and 2'' adapters for the assembly.

Solar Discover Assembly vs. Antlia CaK Solar Herschel Wedge

Antlia's CaK 3nm Solar Herschel Wedge already has its CaK 3nm filter screwed in. Compared with the wedge, the Solar Discover 3nm CaK assembly has a new tube structure design, is designed with 1.25'' and 2'' adapters, and adds light-reducing filters.

The 3nm CaK filter and the light-reducing filters are assembled in a fully closed tube, and installation is similar to the wedge, with the telescope at one end and the camera at the other.

Imaging Only: Why the 393.3nm Line is Not for Visual Use

Antlia states the Solar Discover 3nm CaK assembly is primarily used for solar imaging and is not recommended for visual observation. The 393.3nm wavelength sits at the extreme violet edge of the visible spectrum and is almost invisible to the human eye, so many people find it difficult to see the information CaK has to offer.

In addition, the IR coating range of the assembly is slightly different from the ISO 12312-2 Standard for Solar Viewers. For tough technical requirements and safety considerations, Antlia does not recommend it for visual observation, and stresses that all filters built into the assembly must be in good condition for safety. Use it with a camera.