{"id":29093,"date":"2025-09-20T20:14:25","date_gmt":"2025-09-20T18:14:25","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=29093"},"modified":"2026-07-20T14:51:15","modified_gmt":"2026-07-20T12:51:15","slug":"optolong-sii-filter-2-inch","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/optolong-sii-filter-2-inch\/","title":{"rendered":"Optolong SII Filter 2 inch"},"content":{"rendered":"

Optolong SII Filter 2 inch: one emission line, maximally isolated<\/strong><\/h2>\n\n\n\n

This filter isolates the SII emission line around 672 nm with a half-width of 6.5 nm. All other light, including streetlights and moonlight, is blocked. This makes the sky background very dark and brings out the nebula's 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 the sulfur channel of Hubble palette (SHO) recordings of emission nebulae like the Rosette Nebula and the Eagle Nebula. Because light pollution is almost completely blocked, you can also photograph from the city and in moonlight with this.<\/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