Optolong L-Pro (L-Professional) is a multi-bandpass filter which selectively suppresses the transmission of light pollution lines. For example, mercury vapor lamps, high and low pressure sodium vapor lights and skyglow 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 targets in combination with strong light pollution rejection.  This filter is Optolong's strongest light pollution filter that isn't a narrowband filter (such as the or ).

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 the threaded both sides version) have threads on one side to keep them very thin - 1.85mm not including the threads - they can be used with , , focusers with a place to thread focal 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. 

The threaded both sides version however can be used like an adapter ring and can be threaded directly into your optical train without any additional equipment required. The threaded both sides version has a thickness of 7.6mm 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" and 77mm) | 1mm (clip series)
Made on Schott substrate
Finely polished to 1/4 wave accuracy
Surface quality: 60/40 (MIL-O-13830 standard)

Best Uses

Monochrome & one-shot-color CCD/CMOS camera
Deep sky color imaging, particularly reflective nebula and galaxies

Canon EOS FF Available for: EOS 5D/5DmarkII/III and 6D only

Nikon FF Available for: D600/D610/D700/D750/D800/D800E/D810/D810A/DF

Sony FF Available for: A7M/A7M2/A7M3/A7R/A7R2/A7R3/A7S/A7S2/A9.  Works with the Mark I series Sony cameras (a7, a7r, a7s).  May not fit into newer generation Sony cameras.

Specifications