Optolong 2" L-Quad Enhance Broadband Filter - LQUAD2

The Optolong L-Quad Enhance Broadband Filter is designed for light pollution suppression with color cameras.  The L-QEF is a quad bandpass filter lowers the light generated by mercury and sodium lamps as well as natural skylight.  When used with a color CMOS camera, contrast is enhanced and objects are more distinct.  The filter provides better color balance while improving resistance to light pollution.  This 2" L-Quad filter can be used for wide field astrophotography and deep-sky objects like nebulae, galaxies, star clusters and more.  It maximizes the color balance of nebulae, galaxies and other broadband spectral targets.

Major Emission Lines of Nebulae:

H-a - 656.3nm

H-b -486.1nm

OIII - 495.9nm

OIII - 500.7nm

Major Emission Lines of Artificial Light Pollution

Hg - 435.8nm, 546.1nm, 577nm, 578.1nm

Na - 598nm, 589.6nm, 615.4nm, 616.1nm

Features of the L-Quad Enhance 2" Filter

• Cuts out light pollution from mercury and sodium lamps and produces a nice broadband image with minimal color cast;

• Signal-to-noise ratio (SNR);
  

• Near IR cut-off to 1000nm, reducing the effects of IR noise;
  

• L-QEF has more than 90% transmittance of the nebula emission lines at H-Beta/OIII/H-Alpha/SII, with cut-off depth from OD2 to OD4, thus providing a significant increase in resistance to light pollution. L-QEF is good for night sky from Bortel 1 to Bortel 7 levels; (Bortel 8, Bortel 9 environments are not  recommended);
  

• Suitable for wide range of deep sky targets: it covers most nebulae, galaxies, star clusters, reflected and emitted line signals astronomical objects with higher contrast and rich details while maintaining excellent color balance. 
  

 Technical Data

• Substrate:  Optical glass
  
• Thickness:  1.85 mm
  
• Surface Quality: 60/40 (Refer to MIL-O-13830)
  
• Fine-optically polished to ensure accurate 1/4 wavefront and < 30 seconds parallelism over the both surfaces
• Blocking Range:  300 nm - 1000 nm
  
• Blocking Depth:  OD2 - OD4
  
• Parallelism: 30s
  
• Multi-layers of anti-reflection coating
• FWHM:  Quad bandpass filter