{"id":29000,"date":"2025-09-20T19:53:48","date_gmt":"2025-09-20T17:53:48","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=29000"},"modified":"2026-08-25T15:10:45","modified_gmt":"2026-08-25T13:10:45","slug":"optolong-l-para-filter-2-inch","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/optolong-l-para-filter-2-inch\/","title":{"rendered":"Optolong L-Para Filter 2 inch"},"content":{"rendered":"

Optolong L-Para Filter 2 inch: dual-band for fast optics from f\/2<\/strong><\/h2>\n\n\n\n

The L-Para (L-Parallels) is the dual-band filter that Optolong has specially designed for very fast optics. The 10nm passbands around H-alpha (656.3nm) and OIII (500.7nm) maintain a transmission of over 85 percent on the emission lines, even at aperture ratios of f\/2 to f\/4.<\/p>\n\n\n\n

For such fast systems, think of RASA and Hyperstar setups, light falls on the filter at steep angles and narrower filters lose a lot of signal. The L-Para is designed for this and combines that with greatly improved anti-halo properties around bright stars.<\/p>\n\n\n\n

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Who is L-Para for<\/h4>\n\n\n\n

Owners of fast astrographs photographing emission nebulae with a color camera. Optolong recommends the filter for skies up to Bortle 7; it also works well on slower telescopes.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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

Multi-layer ion-assisted coatings provide a stable central wavelength through temperature fluctuations. The 2 mm thick glass is housed in a thin 2 inch mount with M48 threading.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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

A clear focus filter speeds up focusing; we're happy to include one.<\/p>\n\n\n\n

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