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.

L-Pro enhances the transmission of major emissions from nebula while offering great colour 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 colour 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).  

Highlights

• 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)

 Recommended applications

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

Before & After

Direct JPEG output

Author: Jerry Huang D810A, 180s, ISO1600, FLT132

L-Pro Superior Colour Balance

The comparison image says it all.

Available in sizes

• 1.25" (26mm clear aperture)
• 36mm round unmounted
• 2" (45mm clear aperture)

Coating technologies

• Multi layers anti-reflection coating
• Non cementing optical substrate coating
• Electron-beam gun evaporation with ion-assisted deposition coating technology to enhance coating durability and resistance to scratching as well as stability on central wavelength such that passband does not deviate with temperature change
• Planetary rotation system offers high precision and homogeneity of coating surface ensuring high value on passband transmission and off-band blocking. 

Filter cell technologies

• CNC machined with aerospace grade aluminium
• Black anoidised finish and extinction treatment to prevent refection
• Laser engraved fade-free wordings 

We care about delivering your filter in perfect form and thus every Optolong filter sits on a high density sponge carton lining and packaged in highly rigid plastic PP case with high pressure EVA case lining. 

User gallery

Author: 有翅膀的眼睛 Himalaya base camp_altitude 4950m Camera: EOS 6D mod Lens: Canon 24mmf1.4 Filter: Optolong EOS-FF L-Pro

Author: 星河小将(China) Mount: iOptron CEM25 Optics: Sharp Star 65Q CCD: Atik460 Filter: Optolong L-pro Total exposure: 135 mins

Author: 星河小將 (China) Mount: iOptron CEM25 Optics: Sharp Star 65Q CCD: Atik460 Filter: Optolong L-pro Total exposure: 105 mins

About Optolong

Optolong is a brand dedicated for astronomical filters R&D and production under Kunming Yulong Optical & Electronics Technology Co. Ltd. Yulong is a professional manufacturer of high quality filters since 1999. Yulong has passed ISO9001 quality certifcation and all products meet ROHS standard authorised by SGS test. 

Their major equipment include ultra clean room, five precise vacuum coating machines, Shimadzu UV-VIS-NIR spectrophotometer, 12 sinks ultrasonic cleaning machines and grinding/rolling/cutting machines.

Optolong filters only use the best glass — German's Schott glass as the substrate which has an industry leading level of flatness which is crucial to minimise the occurence of halo and ensure high quality image.