Skip to content

DayStar 150mm ERF with 210mm Inside Diameter Cap

by DayStar
SKU E-210N150
Original price $1,645.00 - Original price $1,645.00
Original price
$1,645.00 - $1,645.00
Current price $1,645.00
In stock

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

Ships In: 1-3 Business Days

Estimated Delivery Time: 3-7 Business Days

Shipping & Returns

We offer Free Shipping across the United States (Lower 48 States) on most orders over $100 USD.

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

We also offer a 30 Day Return Policy on most of the products that we carry. Some limitations may apply.

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 150mm Energy Rejection Filter with 210mm Inside Diameter Cap - For Refractor - E-210N150

Meet the DayStar 150mm Energy Rejection Filter with a 210mm Inside Diameter Cap, designed specifically for refractor telescopes.

These cutting-edge filters have been meticulously crafted to significantly diminish the thermal stress on your filter assembly.

This is accomplished by proficiently absorbing or deflecting UV and/or I light, allowing seamless transmission of light within the desired visual spectrum.

You have the option of choosing between variants featuring Red or Yellow glass, or utilizing advanced dielectric IR and UV materials.

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

It's worth noting that the ERF also serves as an aperture mask, ensuring a direct angle of incidence for incoming light, thereby enhancing filtering efficiency.

For the best results, DayStar recommends operating filter assemblies at f/30 or slower.

Achieving this configuration is easily done with the appropriate ERF and/or Barlow.

In cases where higher resolution or larger aperture configurations are involved, including a Barlow is recommended 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 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 machined 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:

  • 150mm Energy Rejection Filter (ERF) Glass: Is an intricately designed optical element engineered to effectively mitigate thermal effects on your filter assembly. This is accomplished through the adept absorption or reflection of UV and IR light, ensuring that only the desired visual spectrum is allowed to pass through. This deliberate filtration process ensures a consistently sharp viewing experience, effectively minimizing any potential disruptions arising from thermal influences.

  • Effective Thermal Management: The DayStar Energy Rejection Filter is meticulously designed to significantly reduce the thermal impact on your filter assembly. By adeptly absorbing or reflecting UV and/or IR light, it selectively permits only light within the desired visual spectrum to pass through. This ensures a consistently clear viewing experience while minimizing any thermal disturbances.
  • Tailored Filtration Options: Customized to meet specific observational requirements, this filter offers a versatile range of material choices. Whether you opt for Red or Yellow glass or choose dielectric coatings, each option excels at effectively blocking unwanted UV and IR wavelengths. This adaptability perfectly aligns with your precise objectives.
  • Uncompromising Optical Precision and Clarity: While effectively screening out UV and IR, this filter truly excels in transmitting light within the desired visual spectrum. This unwavering commitment to optical clarity guarantees that your observations maintain a standard of precision, free from distortions, and unmatched in their clarity.
  • Enhanced Aperture Mask Functionality: Beyond its primary filtering function, the Energy Rejection Filter (ERF) also serves as an aperture mask. This ensures that incoming light reaches the telescope's optics at a direct and optimal angle, significantly enhancing the quality and precision of your observations.
  • Optimal Performance Configuration: DayStar recommends configuring filter assemblies at f/30 or slower settings for peak performance. Achieving this setup is a straightforward process with the inclusion of the appropriate ERF and, if needed, a Barlow lens. This ensures a seamless integration within your telescope's optical system.
  • Wide Compatibility and Expert Guidance: DayStar offers an extensive list of compatible reflectors and refractors, simplifying your selection process. If you have a specific telescope model in mind, their experienced team is readily available to assist you in choosing the perfect filter for your equipment.
  • Critical Precision in Measurement Requirement: To streamline the customization process, it is crucial to specify the telescope model and provide an accurate measurement (using a ruler) of the outer (largest) diameter of your telescope's dew shield at the front. This precision is essential, as each ERF is individually machined to ensure seamless integration with your telescope.
  • Robust and Protective Construction: The ERF is securely housed in a sturdy cell with a 210mm ID cap. This additional layer of protection ensures the filter's durability and sustained high performance by safeguarding it when not in use.


                        What's Included:

                        ✓ DayStar 150mm ERF with 210mm ID Cap

                        ✓ 5 Year Warranty



                        SKU E-210N150
                        Block Ultraviolet Yes
                        Block Infrared Yes


                        Customer Reviews

                        Be the first to write a review