Antlia Solar Discover Dualband ERF

Dual-Wavelength Access: 25nm Passbands at H-alpha and CaK

The filter has two passbands. A 25nm FWHM band centered at 656.3nm passes the H-alpha line, and a second 25nm FWHM band centered at 393nm covers both the Calcium-K (393.3nm) and Calcium-H (396.8nm) lines. Each band has peak transmission above 90%, so one ERF serves solar imaging equipment working at either H-alpha or Calcium wavelengths.

UV and IR Blocking with a 200-1700nm Coating Range

The Antlia Dualband ERF is very effective at blocking UV and IR light while letting Ha 656.3nm, CaK 393.3nm and CaH 396.8nm pass through. Its coatings cover 200-1700nm. By rejecting heat before it enters the telescope, it protects your solar imaging equipment from high temperature and bandpass shifting.

Lambda/4 Wavefront on a Heat-Resistant Quartz Substrate

The Antlia Dualband ERF is coated on a heat-resistant, double-polished quartz glass substrate and finished with multi coatings. Its transmitted wavefront is Lambda/4 or better. The 130mm, 150mm and 200mm filters are 10mm +/-0.05mm thick, and the 2" mounted filter is 3mm +/-0.05mm thick.

Mounting: Front Cells and 2" Mounted Version

The 130mm, 150mm and 200mm versions are mounted in a housing/cell that holds the filter in front of the telescope, for fixed diameters of 135-190mm, 165-220mm and 195-250mm respectively. The 2" mounted version is installed on the back end of the refractor and must be used on refractors of 110mm or smaller.

• Critical Safety Note: This ERF is a component, not a complete solar filter. It cannot be used on its own and must be used together with professionally made solar imaging equipment that has its own complete blocking filters assembled, such as the Antlia Solar Discover 5Å CaK, Solar Discover 3nm CaK or Dualband Ha, CaK and CaH filter assemblies.
• Visual Use Prohibited: Under no circumstances should this filter be used by itself for direct visual observation of the sun. It does not provide sufficient protection for the human eye.