{"id":28848,"date":"2025-09-19T11:59:03","date_gmt":"2025-09-19T09:59:03","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=28848"},"modified":"2026-10-13T11:15:36","modified_gmt":"2026-10-13T09:15:36","slug":"optolong-filters-l-ultimate-125","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/optolong-filters-l-ultimate-125\/","title":{"rendered":"Optolong L-Ultimate 1.25\u201d"},"content":{"rendered":"

Optolong L-Ultimate 1.25\u201d: 3 nm dual-band, the top of the L-series<\/strong><\/h2>\n\n\n\n

The L-Ultimate is Optolong's narrowest and most advanced dual-band filter: 3 nm passband on both the H-alpha line (656.3 nm) and the OIII line (500.7 nm). Virtually all other light, from streetlights to moonlight and skyglow, is blocked.<\/p>\n\n\n\n

With this bandwidth, you can photograph emission nebulae with maximum contrast and signal-to-noise ratio, even from the inner city. The filter is also optimized against haloes: the image remains clean even around bright stars. The 1.25-inch version fits into nosepieces and filter wheels with a 1.25-inch connection.<\/p>\n\n\n\n

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For the discerning image creator<\/h4>\n\n\n\n

Those who want to take their dual-band work to the highest level will arrive at 3 nm. However, the dark background and fine nebula structure that this filter delivers require precise focusing and a stable mount.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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

The optical glass is 1.85 mm thin, planoptically polished, and features multi-layer ion-assisted coatings for high transmission, temperature stability, and scratch resistance.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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

A clear focus filter is practically indispensable at 3 nm for fast focusing; we are happy to provide that.<\/p>\n\n\n\n

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