Daystar Filters Energy Rejection Filters 100/150 mm

Daystar Filters Energy Rejection Filters 100/150 mm

Description

Daystar Energy Rejection Filters (ERF) are designed to significantly reduce the amount of heat entering the optical system during solar observation. They block ultraviolet and infrared radiation while allowing the useful portion of the visible spectrum to pass. Depending on the version, the ERF may be made of colored glass or dielectric-coated glass for efficient UV and IR suppression.

In addition to thermal reduction, ERFs act as aperture masks to ensure the correct angle of incidence required for Daystar filters, which perform best at f/30 or slower. This configuration can be achieved by reducing the effective aperture or using a suitable Barlow lens.

The correct reduced aperture is calculated by dividing the telescope focal length by 30. When using a Barlow lens, the adjusted focal length must be considered. The 100/150 mm model includes a 100 mm ERF glass mounted in a front cell designed for refractor tubes up to 150 mm in outside diameter.

This ERF ensures stable thermal management, maintains optical consistency during long solar sessions, and optimizes performance with Daystar H-alpha filters. It is an essential accessory for safe and efficient solar observation across a wide range of refractors.

Technical specifications

• UV/IR thermal reduction

• Visible spectrum transmission

• Colored or dielectric-coated glass

• Aperture mask functionality

• Recommended focal ratio: f/30 or slower

• Compatible with Barlow lenses

• Aperture calculation: focal length ÷ 30

• ERF glass diameter: 100 mm

• Mounting cell fits tubes up to 150 mm OD

• Suitable for many refractors

• Optimized for Daystar solar filters

• Enhanced optical and thermal stability

• H-alpha compatible depending on filter used