Hutech Energy Rejection Filters


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  • The external filter prevents the telescope inside from heating up.
  • High-quality interference type of filter
  • 60nm bandpass (central wavelength : 656.28nm)
  • Over 95% transmission at Ha emission line
  • OD 4 between 200nm and 1100nm
  • Glass thickness : 12.0mm
  • The filter assembly is comprised with a filter holder unit and a dew-shield adapter.
  • Available at 190mm, 140mm and 120mm effective apertures at this moment.
  • The set comes with a customized dew-shield adapter. So perfectly fits your scope.
  • The dew-shield adapters will be sold separately as an optional items later. So each user can switch ERF to another telescope by changing only the dew-shield adapter.
  • A couple of weeks lead time due to the custom-made process.
  • Affordable price in its size and quality
  • We have the mechanical data on following telescopes as of August 23 2022.

BORG : 150ED/125ED/107FL/100ED/90FL/76ED

Sky-watcher : EvoStar 150ED/120ED

Takahashi FS128/TOA130

IStar 204


  • Specify us the accurately measured circumference data for the dew-shield if your scope is not listed above.



Additional information

Clear Aperture Diameter

190mm, 140mm, 120mm


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