Optolong L-extreme Filter 1.25" & 2"

The Optolong L Extreme is a high performance dual band nebula filter designed for astrophotographers who want maximum contrast even under strong city light pollution. It isolates two powerful emission lines, Hydrogen Alpha at 656 nm and Oxygen III at 500.7 nm, while blocking almost the entire visible and infrared spectrum of unwanted sky glow. The result is incredibly clean nebula data with rich colour, sharp detail and an excellent signal to noise ratio.
 
This filter is especially effective for emission nebulae such as the Crescent, North America, Rosette, Heart and Soul, Lagoon, Trifid and many planetary nebulae. It allows one shot color cameras and DSLR systems to achieve near narrowband quality without the complexity of multi filter setups.

Key Technical Features
Dual band filter with 7 nm bandwidth for both Ha and OIII
Ha at 656 nm and OIII at 500.7 nm with more than ninety percent peak transmission
Blocks more than ninety nine percent of light pollution from 300 to 1000 nm
Substrate: B270 optical glass
Thickness: 1.85 mm
Surface quality: 60 to 40
Wavefront RMS: Lambda by 4
Parallelism: 30 seconds

Performance and Compatibility Excellent for fast telescopes from f2 to f4 and equally effective on slower systems up to f10 Suitable for refractors, Newtonians, SCTs and dedicated astrographs Optimised for one shot colour cameras, CMOS sensors, DSLR and mirrorless systems Great for imaging nebulae under heavy city lights or suburban skies Reduces star halos while keeping nebula structures crisp