• DayStar 150mm ERF Energy Rejection Filter with 200mm Cap — Premium Solar Filter for High-Resolution H-Alpha Observation
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Daystar

DayStar 150mm ERF Energy Rejection Filter with 200mm Cap — Premium Solar Filter for High-Resolution H-Alpha Observation

DayStar 150mm ERF Energy Rejection Filter with 200mm Cap — Premium Solar Filter for High-Resolution H-Alpha Observation

$1,645.00
$1,645.00
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The DayStar 150mm ERF (Energy Rejection Filter) is a premium front-mounted solar filter for high-resolution H-alpha observation. This full-aperture red-glass filter slides onto the front of your telescope and blocks most of the Sun's ultraviolet and infrared energy while passing the visible red light around the hydrogen-alpha line (~656nm). Removing that heat before it reaches your Quark or Quantum sub-filter keeps the filter cool, protects it, and steadies the image — critical at large apertures where heat load is highest.

This version has a 150mm clear optical aperture in a cell with a 200mm cap (inner diameter) that slides over telescopes with a matching front or dew-shield diameter. Ships free to the US.

Safety note: a red-glass ERF is a pre-filter, not a complete solar filter. It must be used together with a proper H-alpha filter (Quark/Quantum) or solar telescope — never view the Sun through the ERF alone.

Who it's for
Advanced solar imagers and observers running a DayStar Quark or Quantum on a large 150mm telescope for maximum resolution. New to filters? See our guide to telescope filters.

  • Full-aperture red glass: blocks most UV and IR, passes visible light including H-alpha.
  • High-resolution ready: 150mm of aperture for the finest solar detail your seeing allows.
  • Reduces heat load: protects your Quark/Quantum sub-filter and improves image stability.
  • 200mm cap (ID): slides over the telescope's front cell or dew shield.
  • Essential at large apertures: the more aperture you use, the more heat an ERF must reject.
Specifications
Type Front energy-rejection filter (red glass)
Clear Aperture 150mm
Cap ID 200mm (slides over telescope front)
Function Blocks UV/IR, passes visible (incl. H-alpha ~656nm)
Recommended For Large-aperture, high-resolution H-alpha setups
Model / SKU E-200N150

What does an ERF do?
It removes most of the Sun's heat-generating UV and infrared before it reaches your H-alpha filter, protecting the filter and steadying the view.

Do I need one?
Yes at this aperture — a front ERF is essential for safe, stable H-alpha viewing on large telescopes.

How do I choose the cap size?
Match the cap inner diameter to your telescope's front cell or dew-shield outer diameter — this one has a 200mm cap.

Is it a complete solar filter?
No. It is a pre-filter used with a Quark or Quantum H-alpha filter — never view the Sun through the ERF alone.

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Frequently Asked Questions

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