Skip to content

DayStar 80mm ERF with 120mm Inside Diameter Cap

by DayStar
SKU E-120N80
Special Order
Original price $550.00 - Original price $550.00
Original price
$550.00 - $550.00
Current price $550.00


Ships To: United States & Canada 🇺🇸 🇨🇦

✓ Free U.S. Shipping (on most orders over $150 USD)

✓ Price Match Available

✓ Authorized Dealer

✓ Bulk Order Discounts Available

✓ Questions? Call Us 1-800-860-3429

Shipping & Returns

We offer free U.S. shipping to the lower 48 States - on most orders over $150 USD. Some limitations may apply.

Shipping fees will apply on most orders shipping across Canada, with some exceptions.

We offer a 30 Day Return Policy on most of the products that we carry.

For full details on our Shipping & Returns Policy, please click here.


The vast majority of products that we sell, with a few exceptions, are covered under Warranty.

To view the Warranty details for each brand that we sell, including products that do not qualify for Warranty, please visit here.

DayStar 80mm Energy Rejection Filter with 120mm Inside Diameter Cap - For Refractor - E-120N80

The DayStar 80mm Energy Rejection Filter featuring a 120mm Inside Diameter Cap, custom-designed for refractor telescopes.

These cutting-edge filters are meticulously crafted to significantly alleviate the thermal stress on your filter system.

They achieve this by proficiently absorbing or deflecting UV and/or Infrared light, ensuring seamless transmission of light within the desired visual range.

You can choose from variations with Red or Yellow glass, or opt for models utilizing advanced dielectric IR and UV materials.

These filters guarantee precise filtration while allowing the passage of desired wavelengths.

Noteworthy is the ERF's dual function as an aperture mask, guaranteeing a direct angle of incidence for incoming light, thereby heightening filtering efficiency.

For optimal results, DayStar recommends operating filter systems at f/30 or slower.

Achieving this setup is effortlessly accomplished with the appropriate ERF and/or Barlow. In cases of higher resolution or larger aperture configurations, incorporating a Barlow is advised for an even more enhanced viewing experience.

 Important Instructions:

To facilitate a seamless integration, after your order is placed, please reach out to us via email with the following details:

  • Please indicate the telescope intended for use with this ERF and carefully measure the outer diameter of the telescope's dew shield at the front using a ruler. This precise measurement is crucial, as ERFs are individually custom made to guarantee a flawless fit.
  • If this measurement is not provided, it may lead to a temporary hold on your order until the necessary information is obtained. Your satisfaction and optimal performance is our priority.


Features & Highlights:

  • 80mm Energy Rejection Filter (ERF) Glass: Expertly crafted optical component meticulously designed to effectively mitigate thermal influences on your filter assembly. Through expert absorption or reflection of UV and IR light, it selectively permits only the desired visual spectrum to pass through. This deliberate filtration technique ensures a consistently crisp viewing experience, reducing any possible disturbances arising from thermal effects.
  • Heat Load Reduction: Efficiently designed, the DayStar Energy Rejection Filters are engineered to alleviate the heat load on your filter assembly. By adeptly absorbing or reflecting UV and/or IR light, they allow only light within the desired visual spectrum to pass through. This safeguards your telescope's optical components from excess heat, ensuring a consistent and reliable performance.
  • Diverse Filter Materials: Tailoring to specific observational needs, these filters offer a range of material options including Red or Yellow glass, and dielectric coatings. Each option is adept at blocking unwanted UV and IR wavelengths, providing adaptability to your specific goals and requirements.
  • Optical Clarity in the Visual Spectrum: While effectively screening out UV and IR, these filters excel at transmitting light within the desired visual spectrum. This guarantees that observations and images captured with these filters are characterized by clarity, precision, and freedom from distortions.
  • Aperture Mask Functionality: Distinguished as an Energy Rejection Filter (ERF), it also serves as an aperture mask. This ensures that incoming light strikes the telescope's optics at a direct and optimal angle, further enhancing the quality of your observations.
  • Optimal Operating Conditions: DayStar filter assemblies perform optimally at f/30 and slower settings. Achieving this configuration is made effortless with the inclusion of the appropriate ERF and Barlow, ensuring perfect alignment of your telescope's optical system.
  • Custom Compatibility: To streamline your selection process, DayStar offers a comprehensive list of compatible reflectors and refractors. If you have a specific telescope model in mind, their knowledgeable team is readily available to guide you towards the ideal filter for your equipment.
  • Precision Machining: ERFs are meticulously custom machined, highlighting the dedication to detail and precision in the manufacturing process. This ensures the filter is perfectly tailored to your specific telescope's requirements, guaranteeing a seamless and accurate fit.
  • Measurement Accuracy Requirement: For expedited customization, DayStar kindly requests an accurate measurement of the outer (largest) diameter of your telescope's dew shield at the foremost end. The precision of this measurement is paramount to guarantee the impeccable fit and performance of your ERF. Your satisfaction and optimal viewing experience remain their top priority.
  • Sturdy and Protective Build: The ERF is housed within a robust cell equipped with a 120mm ID cap. This cap serves as an additional safeguard, ensuring the filter's durability and sustained high-level performance, especially when not actively in use.


    What's Included:

    ✓ DayStar 80mm ERF with 120mm ID Cap

     ✓ 5 Year Warranty



    SKU E-120N80
    Block Ultraviolet Yes
    Block Infrared Yes


    Customer Reviews

    Be the first to write a review