Daystar Filters Energy Rejection Filters 100/130 mm

Daystar Filters Energy Rejection Filters 100/130 mm

Description

Daystar Energy Rejection Filters (ERF) are designed to significantly reduce heat entering the optical system during solar observation. They absorb or reflect ultraviolet and infrared radiation while allowing only useful visible wavelengths to pass. Depending on the version, the ERF may be made from colored optical glass or from dielectric-coated glass specifically engineered for strong UV and IR blocking.

An ERF also acts as an aperture mask, ensuring proper angle of incidence for optimal performance of Daystar filters, which operate best at f/30 or slower. This focal ratio can be achieved either by reducing the effective aperture or by pairing the telescope with an appropriate Barlow lens.

To determine the required aperture reduction, the telescope focal length is divided by 30. When using a Barlow, its multiplication factor must be included. The 100/130 mm model includes a 100 mm ERF glass mounted in a front cell that fits refractor tubes with an outside diameter of up to 130 mm.

This ERF provides consistent thermal protection, improved optical stability, and safe long-duration solar observing. It is a key accessory for narrowband solar configurations using Daystar filters across a wide range of refractors.

Technical specifications

• UV/IR thermal load reduction

• Visible spectrum transmission

• Colored or dielectric-coated glass depending on model

• Aperture mask functionality

• Recommended focal ratio: f/30 or slower

• Barlow lens compatible

• Aperture calculation: focal length ÷ 30

• ERF glass diameter: 100 mm

• Mounting cell fits tubes up to 130 mm OD

• Suitable for many refractors

• Optimized for use with Daystar filters

• Enhanced thermal and optical stability

• Suitable for H-alpha depending on filter used