OPTOLONG L-PRO CCD filter (31,7mm)

The L-Pro CCD filter is a filter designed to enhance the contrast of deep sky objects and attenuate the sky background. This is achieved through a complex transmission characteristic that allows the lines of deep sky objects to pass through (H-Alpha, O-III, N-II, H-Beta, S-II, etc.) but suppresses the emissions of stray light (e.g., the Hg line or the emission of sodium vapor lamps). It also reduces the sky background caused by unwanted oxygen emissions from the atmosphere ("skyglow").

This filter is specifically designed for use in light-polluted areas and can be used for both visual and photographic purposes. Unlike other filters designed to mitigate light pollution, such as UHC or CLS filters, the L-PRO CCD is a multi-bandpass filter that minimally affects color reproduction.

The L-PRO CCD filter is also suitable for photographing objects that radiate in the continuum, including emission nebulae, galaxies, globular clusters, reflection nebulae, etc. The L-PRO CCD filter is equally suitable for CCD and DSLR cameras.

Caution!

Optolong filters are not suitable for solar observation; never look at the sun with these filters!

Technical Specifications

• Schott carrier glass Surface quality 60/40 (equivalent to E-E grade according to US military standard MIL-O-13830) 
• Precisely optically polished, 1/4 wavefront 
• 95% peak transmission in the passband 
• IR blocking 700-1100nm in the stopband/offband 

Coating properties:

 Highly homogeneous multi-layer anti-reflection coating. The coatings are not cemented to the optical carrier, but are applied by electron beam evaporation and subsequent ion beam-assisted deposition (IBAD process). This special process enables extreme durability and scratch resistance, as well as high central wavelength stability (CWL), and prevents temperature drift. High transmission in the passband, high optical density in the stopband.

Filter Mount: 

• Ultra-thin filter mount for maximum aperture: 26mm for 1.25" filters, 45mm for 2" filters 
• Precise CNC machining 
• Sandblasted 
• Black anodized 
• Blackened to prevent reflections 
• Laser engraving - no fading of the markings