Skip to content

DayStar 100mm ERF with 150mm Inside Diameter Cap

by DayStar
SKU E-150N100
Special Order
Original price $695.00 - Original price $695.00
Original price
$695.00 - $695.00
Current price $695.00

Lead-time: 2-4 weeks

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 100mm Energy Rejection Filter with 150mm Inside Diameter Cap - For Refractor - E-150N100

Introducing the DayStar 100mm Energy Rejection Filter, featuring a 150mm Inside Diameter Cap, expertly designed for refractor telescopes.

These advanced filters have been meticulously crafted to dramatically reduce the thermal strain on your filter assembly.

They accomplish this by efficiently absorbing or reflecting UV and/or infrared light, while flawlessly transmitting light within the desired visual spectrum.

Choose from variations in Red or Yellow glass, or opt for filters made from dielectric IR and UV materials, ensuring precise filtration while allowing the passage of desired wavelengths.

What sets this ERF apart is its dual functionality as an aperture mask, guaranteeing a direct angle of incidence for incoming light, thereby enhancing filtering efficiency.

To achieve optimal performance, DayStar recommends operating filter assemblies at f/30 or slower.

Achieving this configuration is made effortless with the right ERF and/or Barlow lens. In cases where higher resolution or larger aperture setups are in use, including a Barlow is advised for an enriched 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 designated for use with this ERF and carefully ascertain the outer diameter of the telescope's dew shield at the front using a ruler. This exact measurement is crucial, as ERFs are custom made to guarantee a seamless fit.
  • If this measurement is not provided, it may lead to a temporary pause on your order until the required information is obtained. Your satisfaction and optimal performance is our priority.


Features & Highlights:

  • 100mm Energy Rejection Filter (ERF) Glass: A precision-engineered optical element created to effectively mitigate thermal effects on your filter assembly. Through adept absorption or reflection of UV and IR light, it selectively permits only the desired visual spectrum. This meticulous filtration ensures a consistently clear and uninterrupted viewing experience, free from any thermal disturbances.

  • Exceptional Heat Management: The DayStar Energy Rejection Filters are skillfully designed to alleviate excessive heat from your filter assembly. Through adeptly absorbing or reflecting UV and/or IR light, they exclusively allow light within the desired visual spectrum. This protective measure ensures a dependable and unwavering performance by safeguarding the telescope's crucial optical components.
  • Versatile Material Choices: Tailored to specific observational needs, these filters offer a diverse array of materials. Select from Red or Yellow glass, or opt for dielectric coatings. Each option excels in blocking unwanted UV and IR wavelengths, providing adaptability aligned with your precise goals.
  • Brilliance in the Visual Spectrum: While efficiently screening out UV and IR, these filters excel in transmitting light within the desired visual spectrum. This unwavering commitment to clarity ensures that observations and images captured with these filters are characterized by precision, freedom from distortions, and unparalleled clarity.
  • Dual-Purpose Aperture Mask: Functioning both as an Energy Rejection Filter (ERF) and an aperture mask, it guarantees incoming light meets the telescope's optics at an ideal and direct angle. This dual role significantly enhances the quality and precision of your observations.
  • Optimal Operational Parameters: DayStar filter assemblies attain their peak performance at f/30 and slower settings. This ideal setup is effortlessly achieved with the inclusion of the appropriate ERF and Barlow, ensuring perfect alignment within your telescope's optical system.
  • Tailored Compatibility: Simplify your selection process with DayStar's comprehensive list of compatible reflectors and refractors. If you have a specific telescope model in mind, their experienced team is ready to assist you in finding the perfect filter for your equipment.
  • Exacting Precision in Manufacturing: ERFs undergo meticulous custom machining, underscoring an unwavering dedication to detail and precision in the production process. This guarantees the filter is flawlessly tailored to meet the unique requirements of your telescope, ensuring a seamless and accurate fit.
  • Critical Measurement Request: To expedite the customization process, DayStar kindly requests an accurate measurement of the outermost (largest) diameter of your telescope's dew shield at the foremost end. This level of precision is crucial in securing an impeccable fit and ensuring optimal performance of your ERF. Rest assured, your satisfaction and superior viewing experience remain their top priorities.
  • Sturdy and Safeguarding Build: Housed within a resilient cell with a 150mm ID cap, the ERF boasts an added shield. This cap offers supplementary protection, preserving the filter's integrity during periods of non-use, thereby ensuring its enduring performance and longevity.


      What's Included:

      ✓ DayStar 100mm ERF with 150 ID Cap

      ✓ 5 Year Warranty



      SKU E-150N100
      Block Ultraviolet Yes
      Block Infrared Yes


      Customer Reviews

      Be the first to write a review