OPTOLONG L-PRO 1.25'' Anti-Pollution Filter for CCD & DSLR Cameras, 90% Transmission of Main Nebulous Emission Lines, Optical Glass, 77.0mm

The Optolong L-Pro (L-Professional) 1.25" filter is designed to provide maximum spectrum brightness and improve the visibility of various deepsky objects, particularly nebulose objects, by selectively reducing the transmission of wavelengths of light pollutants, especially those produced from artificial lighting including mercury vapour lamps, high and low pressure sodium vapour lamps and unwanted natural light caused by the Neutral oxygen emission in our atmosphere (i.e. skyglow).
Since this filter is highly transparent in the main nebulous emission lines to OIII (496nm and 500nm), H-beta (486nm), NII (654nm and 658nm), H-alfa (656nm) and SII (672nm), the filter is suitable for improving contrast and detail for both visual and photogrographic purposes in sub-rural areas with strong light pollution.
Unlike other UHC and CLS pollution filters, L-Pro is a multi-pass filter that offers better color balance by maximizing the transmission bandwidth. Balanced transmission allows you to take astrophotographs with a minimum color dominant for broadband objects such as galaxies, reflection nebulas and globular star clusters.
WARNING: Optolong filters are not designed for sun observation. Do not seal the sun with the OPTOLONG filter.
Technical data
Schott substrate material Glass thickness 2.0 mm (1.25 inches/2 inches/77 mm) and 1.0 mm (clip series) Surface quality: 60/40 (refer to MIL-O-13830) Optimised at optical level to ensure accurate 1/4 of the wavehead and parallel <30 seconds on both surfaces Transmission of 90% of the main nebulous emission lines (i.e. it 656nm, OIII 496nm and 500nm, SII 672nm and H-beta 486nm)