Solarscope Ltd. is a family owned manufacturer of premium quality hydrogen alpha filters. Filters up to 100mm are available as standard in single-stack (<0.5 Angstrom FWHM) and double-stack (<0.5 Angstrom FWHM) configuration. The air-spaced etalons in the filters are manufactured, assembled and tuned on site by craftsmen with over 30 years experience. The 70mm and 100mm hydrogen filters are the only ones in their size on the market that contain air-spaced etalons with an unobscured coated aperture to ensure the best possible image quality.