{"id":29024,"date":"2025-09-20T19:56:15","date_gmt":"2025-09-20T17:56:15","guid":{"rendered":"https:\/\/www.telescoop.nl\/?post_type=product&p=29024"},"modified":"2026-07-20T14:51:08","modified_gmt":"2026-07-20T12:51:08","slug":"optolong-l-ultimate-filter-3nm-2-inch","status":"publish","type":"product","link":"https:\/\/www.telescoop.nl\/en\/optolong-l-ultimate-filter-3nm-2-inch\/","title":{"rendered":"Optolong L-Ultimate Filter 3nm 2 inch"},"content":{"rendered":"

Optolong L-Ultimate Filter 3nm 2 inch: 3 nm dual-band, the pinnacle 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 downtown. The filter is also optimized against halos: the image remains clean even around bright stars. The 2-inch version (M48) prevents vignetting on large sensors and fits into 2-inch filter holders and photographic adapters.<\/p>\n\n\n\n

\"Optolong<\/figure>
\"Optolong<\/figure>
\"Optolong<\/figure>
\"Optolong<\/figure><\/figure>\n\n\n\n
\n
\n
\"Optolong<\/figure>\n<\/div>\n\n\n\n
\n

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

\n
\n
\"Optolong<\/figure>\n<\/div>\n\n\n\n
\n

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