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Optolong Venus U Filter - 1.25" Mounted - VEU-125

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Optolong Venus U Filter - 1.25”

Image the sulphuric acid clouds of Venus or do UV landscape photography with the Optolong 1.25” Venus U Filter. This special filter can only be used for imaging through CCD/CMOS or DSLR cameras* since our eyes are not sensitive to UV light. The Venus U filter passes UV-A light at 320nm to 400nm with a peak transmission of 80%, and blocks 200nm to 280nm as well as everything above 400nm, which include the visible and infrared spectral regions.

*In order to use this filter with a monochrome CCD or DSLR camera, you will need to remove anything that keeps UV light from reaching the sensor. For CCD/CMOS cameras, this would include the sensor’s cover glass and internal UV-IR blocker, and for DSLR’s, the built-in low pass filter would need to be removed. A special UV lens may be required, since some lenses have anti-reflective coatings that block all light below 380nm. Investigate your gear’s specifications to decide what is best for your applications.

The Optolong 1.25” Venus U 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. Each 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 26mm.

Quality Filter Materials:

  • Schott B260 substrate material from Germany, 2.0mm thick
  • CNC machined and black anodized aero-metal filter cell that is ultra-thin to provide largest clear aperture; Laser-engraved to prevent fading
  • Multiple layers of anti-reflection non-cementing coatings applied via electron-beam gun evaporation with Ion-assisted deposition

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
  • 80% maximum transmission at spectral region 320-370nm
  • Precision off-band blocking on ultraviolet wavelength 200-280nm, visible and infrared spectral region
  • Optolong’s planetary rotation system is a homogenous and precise coating procedure that ensures both high transmission of pass-band and optical density of off-band
  • Thin metal cells have a clear aperture of 26mm for 1.25” filters
  • Each filter comes with a plastic case with high pressure EVA case lining

About Optolong

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.