Daystar Filters ERF 125 mm (glass + cell + 460 mm ID cap) – off-axis for SCT telescope (SKU: E-460F125) is an Energy Rejection Filter designed for Schmidt-Cassegrain telescopes used in hydrogen-alpha solar observing systems. Installed at the front of the telescope in an off-axis configuration, the filter significantly reduces the thermal load entering the optical system by absorbing or reflecting ultraviolet and infrared radiation while transmitting the visible spectrum required for H-alpha solar observation.

Key features

• Energy Rejection Filter designed for SCT telescopes
• off-axis configuration reducing thermal load on the optical system
• absorbs or reflects UV and IR radiation
• transmits visible light required for solar observation
• protects H-alpha filter assemblies from excessive heat
• improves stability of solar observing systems such as DayStar Quark and Quantum
• front-mounted installation on the telescope

Box contents

• DayStar 125 mm ERF filter glass
• filter mounting cell
• 460 mm ID mounting cap

Technical specifications

• type: Energy Rejection Filter (ERF)
• filter diameter: 125 mm
• mounting cap inner diameter: 460 mm
• configuration: off-axis
• application: Schmidt-Cassegrain telescopes (SCT)
• mounting position: front of telescope
• compatibility: DayStar H-alpha solar observing systems

ERF filters are an essential component in H-alpha solar observing setups because they reduce the heat reaching the primary solar filter assembly and improve both operational safety and stability during solar observation and imaging.