Optolong L-Pro (L-Professional) is a multi-band-pass filter which selectively suppresses the transmission of light pollution lines. For example, mercury vapor lamps, high and low pressure sodium vapor lights and sky glow caused by emission from neutral oxygen in our atmosphere. The L-Pro works well for galaxies, reflection and emission nebulae and all other emission or reflection targetsin combination with strong light pollution rejection. This filter isOptolong’s strongest light pollution filter that isn’t a narrowband filter (such as the L-eNhance or L-eXtreme).

L-Pro enhances the transmission of major emissions from nebula while offering great color balance with its wide yet effective light pollution cutting transmission band. The balanced transmission allows objects with wide emission spectrum such as galaxies to be imaged with minimal color cast (easier to correct in post-processing). Among the emission lines enhanced are OIII (496, 500nm), H-beta (486nm), NII (654, 658nm), H-alpha (656nm) and SII (672nm). Available in 2″, 1.25″ and selected DSLR camera sizes.

Note: The Optolong L-Pro filters (apart from thethreaded both sidesversion) have threads on one side to keep them very thin – 1.85mm not including the threads – they can be used withFilter Wheels,Filter Drawer System, focusers with a placeto threadfocal reducers internally (such as some Moonlite focusers) and camera nose pieces that fit into compression rings, but the 1.85mm filter should not be threaded into the imaging train like an adapter ring with threads on both sides.

Thethreaded both sides versionhowever can be used like an adapter ring and can be threaded directly into your optical train without any additional equipment required. Thethreaded both sides version has a thickness of7.6mm not including the threads.Note that this size filter will NOT fit in most filter wheels or drawers.

Features

90% transmission at major nebula emission lines
Multi-layers anti-reflection coating
Precise and sharp roll-off at light pollutant lines
2 mm filter thickness (1.25″, 2″) | 1mm (clip series)
Made on Schott substrate
Finely polished to 1/4 wave accuracy
Surface quality: 60/40 (MIL-O-1