Optolong L-Para 2" 10nm Dual Narrow Band Filter

The L-Para is a new 10nm Dual Narrow Band Light Pollution Filter designed for imaging emission nebulae.

The transmittance of the nebulae emission lines is greater than 85%  when used with optical systems with focal ratios of F2 and above. The L-Para effectively filters out mercury lamps, sodium lamps, and LED light pollution emission lines. 

At the same time, it has excellent contrast and anti-halo characteristics, allowing you to capture detailed and vivid nebula images. L-Para is suitable for normal and fast optical systems, such as RASA and Hyperstar. 

Even when light is incident at an oblique angle, the L-Para can maintain high transmission rates to provide a clear and precise shooting experience.

Features

Broad Compatibility: A dual narrowband filter suitable for all telescope systems, adaptable to fast optics (focal ratios of F2, F2.8, F3.2, F4) as well as various standard/normal focal ratio telescopes.

Light Pollution Reduction: Effectively cuts off emission lines from mercury lamps, sodium lamps, LEDs, and other light pollution sources, making it applicable to Bortle Scale1- 7 dark skies. 

High Transmission: In systems with a focal ratio of F2 and above, nebula emission lines OIII and Ha transmittance exceeds 85%, resulting in higher imaging efficiency.

Excellent Contrast: The high transmittance of nebula emission lines (OIII & Ha) combined with a deep cut-off of light pollution bands significantly improves image contrast and detail richness.

Anti-Halo Characteristics: The design has undergone several rounds of optimisation and repeated testing, resulting in a marked improvement in anti-halo performance, enhancing the capture of bright

Spectrum
According to the characteristics of the emission lines of celestial bodies and light pollution, as well as the characteristicas of the normal telescope and fast ratio imaging system, L-Para has been maintaining high transmittance at OIII and Ha while blocking light pollution emission lines.