{"id":29084,"date":"2025-09-20T20:11:36","date_gmt":"2025-09-20T18:11:36","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=29084"},"modified":"2026-08-25T15:10:45","modified_gmt":"2026-08-25T13:10:45","slug":"optolong-h-alpha-filter-7nm-2-inch","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/optolong-h-alpha-filter-7nm-2-inch\/","title":{"rendered":"Optolong H-alpha Filter 7nm 2 inch"},"content":{"rendered":"

Optolong H-alpha Filter 7nm 2 inch: emission line, maximally isolated<\/strong><\/h2>\n\n\n\n

This filter isolates the H-alpha emission line around 656.3 nm with a half-width of 7 nm. All other light, including street lights and moonlight, is blocked. This makes the sky background intensely dark and brings out the nebula structure at this wavelength to the maximum.<\/p>\n\n\n\n

Narrowband filters are the foundation of monochrome camera photography: you photograph the lines separately and combine them into color composites, such as the well-known Hubble Palette (SHO).<\/p>\n\n\n\n

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What you use this filter for<\/h4>\n\n\n\n

Made for emission nebulae, planetary nebulae, and supernova remnants; H-alpha is the most important line for hydrogen-rich nebulae. Because light pollution is almost completely blocked, you can also photograph with it from the city and in moonlight.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Technology<\/h4>\n\n\n\n

The Schott glass is finely optically polished and features multi-layer ion-assisted coatings: high transmission in the passband, strong blocking outside of it, and a central wavelength that remains stable with temperature changes. The thin metal mount minimizes vignetting.<\/p>\n<\/div>\n<\/div>\n\n\n\n

Featured accessories<\/h3>\n\n\n\n

Combine this filter with the other lines (H-alpha, OIII, and SII) for complete narrowband composites. A bright focus filter speeds up focusing.<\/p>\n\n\n\n

For whom yes and for whom no<\/h3>\n\n\n\n