Skip to content

DayStar 100mm Off-Axis ERF with 356mm Inside Diameter Cap

by DayStar
SKU E-356F100
Special Order
Original price $895.00 - Original price $895.00
Original price
$895.00 - $895.00
Current price $895.00

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 Off-Axis Energy Rejection Filter with 356mm Inside Diameter Cap - for 12-inch SCT - E-356F100

Introducing the DayStar 100mm Off-Axis Energy Rejection Filter, equipped with a 356mm Inside Diameter Cap, tailored for 12-inch SCT telescopes.

This specialized filter serves a crucial role in reducing the heat load on your filter assembly.

It achieves this by either absorbing or reflecting UV and/or I light, while allowing light in the desired visual spectrum to pass through.

These filters may come in Red or Yellow glass variants, or employ dielectric materials to block IR and UV, ensuring transmission of light in the visual spectrum.

Moreover, the ERF can also act as an aperture mask, ensuring a direct angle of light entry into the filter.

For optimal performance, DayStar filter assemblies are most effective at f/30 and slower.

Achieving an f/30 configuration is straightforward with the appropriate ERF and/or Barlow lens.

This setup ensures your telescope system operates at its best, delivering high-quality observations and images.

 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 you plan to use with our ERF and carefully measure the outer diameter of the telescope's dew shield at the front with a ruler. This precise measurement is crucial, as we craft ERFs on an individual basis to ensure a flawless fit.
  • Failure to provide this measurement might lead to a temporary delay in your order until we have the required information. Your satisfaction and optimal performance is our priority.

    Features & Highlights:

    • 100mm ERF Glass: Meticulously crafted with precision, the 100mm ERF aperture is skillfully tailored for optimal solar observation. Achieving a delicate equilibrium between light-gathering capacity and resolution, it delivers sharp, finely detailed views of solar phenomena.
    • 356mm Inside Diameter Cap: Included within the package is a 356mm inside diameter cap, ensuring a secure and snug fit with compatible telescopes. This cap plays a pivotal role in minimizing stray light, allowing for precise, uninterrupted solar observations.
    • SCT Compatibility: Designed specifically for 12-inch SCT (Schmidt-Cassegrain) telescopes, the ERF effortlessly integrates with your existing optical setup. This guarantees a seamless, trouble-free, and effective solar observation experience.
    • Advanced Energy Rejection: The ERF is meticulously engineered to substantially reduce the heat load on your filter assembly. This is accomplished through the efficient absorption or reflection of UV and/or Infrared light, facilitating the transmission of light within the desired visual spectrum.
    • Multi-Coated Optics: Every optical surface is expertly multi-coated to enhance light transmission and minimize internal reflections. The outcome is vivid, high-contrast solar images with exceptional clarity and detail.
    • Off-Axis Design: The off-axis design provides an unobstructed view of the solar disk, maximizing the quantity of light collected by the telescope. This design characteristic ensures precise observation of the sun's features.
    • Dual Functionality as an Aperture Mask: The ERF serves a dual purpose as an aperture mask, ensuring a direct angle of incidence for incoming light. This distinctive feature enhances filtering efficiency, guaranteeing that only the desired wavelengths are transmitted.
    • Robust Construction: Constructed from top-quality materials, the ERF guarantees durability and long-lasting performance. It is engineered to endure the rigors of outdoor use and maintain its peak performance over time.
    • Recommendations for Optimal Performance: For optimal results, DayStar recommends operating filter assemblies at f/30 or slower. This configuration is effortlessly achieved with the appropriate ERF and/or Barlow. In cases of higher resolution or larger aperture configurations, the addition of a Barlow is recommended for an enhanced viewing experience.


                What's Included:

                ✓ DayStar 100mm Off-Axis ERF for 12-inch SCT

                 ✓ 5 Year Warranty



                SKU E-356F100
                Block Ultraviolet Yes
                Block Infrared Yes

                Customer Reviews

                Be the first to write a review