Optolong L-Pro Broadband Filter - 2"
This Optolong L-Pro is a broadband filter perfect for astro-imaging with CCD and DSLR cameras as well as for visual observations of celestial objects. By expanding the transmission band, you will notice images of broadband emission objects to have a nominal color cast for optimal color balance. Use the L-Pro filter alone to suppress infrared wavelengths when doing photography, or as a light pollution suppression filter when observing visually.
By reducing the transmission of artificial and natural light pollution, including neutral oxygen (skyglow) as well as light given off from mercury and sodium vapor lamps, the background sky will become darker, allowing the good stuff to shine through. High transmission of main nebulae emission lines at OIII, H-Beta, NII, H-alpha, and SII, when combined with the precision off-band blocking of contrast-killing light pollution, makes this filter perfect for most emission nebulae, reflection nebula, and dark nebulae.
The Optolong 2” L-Pro Filter is made with Schott glass that has been multi-coated with an ion-assisted deposition technology to ensure scratch resistance and stability on the central wavelength, or CWL. The filter cell is made of lightweight, strong metal and is CNC machined, sand-blasted, black anodized, and then laser engraved. The result is a super thin filter cell that will produce a clear aperture of 45mm.
Quality Filter Materials:
- Schott B260 substrate material from Germany, 2.0mm thick
- Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition
- CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture; Laser-engraved to prevent fading
Optolong Filter Manufacturing Processes and Parameters
- Filter substrate is fine-optically polished to 1/4 wave and <30 parallelism over both surfaces
- Surface quality, according to MIL-O-13830, is 60/40
- High transmission at major nebula emission lines (i.e. H-alpha 656nm, OIII 496nm and 500nm, SII 672nm and H-beta 486nm)
- Precision off-band blocking, specifically the major emission lines of artificial light pollution (i.e. Na 589nm, Hg 435nm and 578nm)
- High-value transmission of pass-band and optical density of off-band is assured through Optolong’s planetary rotation system, a homogeneous and precise coating procedure
- Each filter comes with a plastic case with high-pressure EVA case lining
- Thin metal cells have a clear aperture of 45mm for 2” filters
Optolong is the Astronomy Filters division of Yulong Optics, an optical filter design and processing company out of Kunming, China that has provided filters for over 700 optical companies since 1999. All Optolong filters pass European Union RoHS requirements and have been certified by TUV Rheinland and Bureau Veritas.
Optolong 2" L-Pro Filter
- Filter Case
Dimensions & Specifications
Filter Size: 50.8mm (2")
Filter Type: Light Pollution
Filter Shape: Round
Mounted or Unmounted: Mounted
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