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DayStar 130mm ERF with 170mm Inside Diameter Cap

by DayStar
SKU E-170N130
Special Order
Original price $995.00 - Original price $995.00
Original price
$995.00 - $995.00
Current price $995.00

Lead-time: 2-4 weeks

Ships To: United States & Canada 🇺🇸 🇨🇦

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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 130mm Energy Rejection Filter with 170mm Inside Diameter Cap - For Refractor - E-170N130

Discover the DayStar 130mm Energy Rejection Filter with an Inside Diameter Cap of 170mm, specifically designed for refractor telescopes.

These cutting-edge filters have been meticulously engineered to significantly reduce heat-induced stress on your filter assembly.

They accomplish this by effectively either absorbing or reflecting ultraviolet (UV) and/or infrared (IR) light, ensuring the seamless transmission of light within the desired visual spectrum.

The DayStar 130mm ERF is available in several variations, including options with Red or Yellow glass, or those employing high-quality dielectric IR and UV materials.

These filters guarantee precise filtration while permitting the passage of desired wavelengths, making them a valuable asset for your telescope.

What's particularly noteworthy is that the ERF serves a dual purpose as an aperture mask, ensuring a direct angle of incidence for incoming light.

This innovative feature enhances the overall efficiency of the filtering process.

For optimal performance, DayStar recommends using filter assemblies at f/30 or slower.

Achieving this configuration is a straightforward process with the appropriate ERF and/or Barlow lens.

In cases where higher resolution or larger aperture configurations are desired, incorporating a Barlow is advised to elevate your viewing experience to new heights.

Important Instructions:

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

  • Please specify the telescope intended for use with this ERF and meticulously measure the outer diameter of the telescope's dew shield at the front using a ruler. This precise measurement is paramount, as ERFs are custom made on an individual basis to ensure a perfect fit.
  • Failure to provide this measurement may result in a temporary hold on your order until the necessary information is retrieved. Your satisfaction and optimal performance is our priority.


Features & Highlights:

  • 130mm Energy Rejection Filter (ERF) Glass: A precision-engineered optical element created to effectively mitigate thermal effects on your filter assembly. This is achieved through adept absorption or reflection of UV and IR light, permitting only the desired visual spectrum to pass through. This carefully orchestrated filtration ensures a consistently unclouded viewing experience, reducing any potential disturbances caused by thermal influences.

  • Effective Heat Load Reduction: This specialized DayStar Energy Rejection Filter (ERF) is meticulously engineered to significantly reduce the heat load on your filter assembly. Its advanced design allows it to expertly absorb or reflect UV and/or IR light while permitting only the desired visual spectrum to pass through. This safeguard preserves your telescope's vital optical components, ensuring a consistent and dependable performance.
  • Versatile Filter Material Options: The ERF offers a range of material choices, including Red or Yellow glass and dielectric coatings. These options cater to the specific needs of your observations, effectively blocking unwanted UV and IR wavelengths and providing adaptability aligned with your precise goals.
  • Optical Clarity in the Visual Spectrum: While efficiently screening out UV and IR, this filter excels in transmitting light within the desired visual spectrum. This unwavering commitment to optical clarity ensures that your observations and images remain characterized by precision, free from distortions, and unparalleled in their clarity.
  • Dual Functionality as Aperture Mask: The ERF serves a dual role as an aperture mask, ensuring that incoming light meets the telescope's optics at an ideal and direct angle. This dual function significantly amplifies the quality and precision of your observations, contributing to an enhanced viewing experience.
  • Optimal Operating Conditions: DayStar filter assemblies reach their peak performance when configured at f/30 and slower settings. Achieving this configuration is made effortless with the inclusion of the appropriate ERF and/or Barlow, ensuring perfect alignment within your telescope's optical system.
  • Tailored Compatibility: To simplify your filter selection process, DayStar provides a comprehensive list of compatible reflectors and refractors. Additionally, if you have a specific telescope model in mind, their knowledgeable team is readily available to assist you in selecting the ideal filter for your equipment.
  • Precision in Custom Machining: Each ERF undergoes meticulous custom machining to ensure an impeccable fit and performance. This attention to detail underscores DayStar's commitment to precision in the manufacturing process, guaranteeing that the filter is seamlessly tailored to meet the unique requirements of your telescope.
  • Critical Measurement Requirement: To expedite the customization process, DayStar kindly requests that you provide an accurate measurement of the outermost (largest) diameter of your telescope's dew shield at its foremost end. This level of precision is paramount in securing a flawless fit and optimal performance of your ERF. Failing to provide this information may temporarily delay the processing of your order.
  • Durable and Protective Construction: The ERF comes encased in a robust cell with a 170mm ID cap. This cap provides an extra layer of protection, safeguarding the filter when not in use, ensuring longevity and continued high performance.


            What's Included:

            ✓ DayStar 130mm ERF with 170mm ID Cap

            ✓ 5 Year Warranty



            SKU E-170N130
            Block Ultraviolet Yes
            Block Infrared Yes


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