ERF 1.25" Filter S-series for Quark Chromosphere

Product Overview

The Player One Astronomy ERF 1.25″ is an Energy Rejection Filter built to work ahead of a Daystar Quark Chromosphere. It passes roughly 97% of visible light while rejecting ultraviolet and infrared energy to OD4, so the heat load reaching the Quark's internal etalon is reduced and your solar hydrogen-alpha view stays stable and clean. The optic is ground on B270 glass to a PV 1/4 wavelength wavefront, preserving the sharpness your solar scope delivers.

Who It's For

This filter is for solar imagers and observers running a Daystar Quark Chromosphere who want to shed unwanted UV and IR energy before it reaches the eyepiece unit. If you are chasing prominences, filaments, and chromospheric detail and want to lower the thermal load on your Quark, this ERF fits the role.

Key Features & Design

• Energy rejection for solar work: blocks UV and IR to OD4 across 200–1100 nm, cutting heat while passing the visible band your Quark needs.
• High visible throughput: ≈97% transmittance keeps the solar disc bright for comfortable viewing and short exposures.
• B270 optical glass: a proven low-cost optical substrate carrying a multi-layer composite coating.
• PV 1/4λ wavefront: figured to a quarter-wave to protect image sharpness through the imaging train.
• 1.25″ thread (M28.5×0.6): matches the standard 1.25-inch filter thread used on the Quark and 1.25-inch accessories.

Optical/Mechanical Design

The ERF transmits about 97% of visible light while rejecting out-of-band ultraviolet and infrared to optical density 4 (OD4) over 200–1100 nm. That rejection is the whole point of an energy rejection filter: cutting the UV and IR heat load before it reaches a Daystar Quark protects the internal etalon and stabilises the passband, which keeps your Ha contrast consistent through a session. The 2.5 mm-thick optic is made from B270 glass with a multi-layer composite coating and is figured to a PV 1/4 wavelength wavefront. Mechanically it uses the 1.25-inch M28.5×0.6 thread with a 5 mm body plus 2.5 mm thread section (7.5 mm total).

Recommended Uses

• Reducing UV/IR heat load ahead of a Daystar Quark Chromosphere for solar Ha imaging and observing.
• Solar prominence, filament, and chromosphere work where a stable passband matters.
• 1.25-inch solar imaging trains that need visible-band energy rejection.

Compatibility & Accessory Notes

• Fit: 1.25″ M28.5×0.6 filter thread — designed to pair with the Daystar Quark Chromosphere and standard 1.25-inch accessories.
• Placement: used as an energy rejection filter in front of the Quark to lower thermal load.
• Backfocus: the 7.5 mm cell and 2.5 mm glass add to your optical path; keep them in your spacing calculation.

Good to Know Before You Order

• This is an energy rejection filter for use within a properly configured solar imaging setup; it is not a standalone solar safety filter for direct viewing.
• Player One does not publish a net weight for this filter, so the shipping weight shown at checkout is an estimate. Contact us if you need an exact figure.
• Inserting the filter shifts focus slightly, so refocus after fitting it.

FAQ

Is it difficult to set up? No. It threads into the standard 1.25-inch M28.5×0.6 filter thread on your Quark or 1.25-inch train and needs no power; refocus once after fitting.

Why do I want an ERF with a Quark? Rejecting UV and IR energy before it reaches the Quark lowers the heat load on the internal etalon and helps keep the Ha passband stable through a session.

What is the glass made of? B270 optical glass with a multi-layer composite coating, figured to a PV 1/4 wavelength wavefront.

Does it dim the solar disc much? Visible transmission is about 97%, so the disc stays bright while the UV and IR energy is removed.

Bottom Line

The ERF 1.25″ gives your Daystar Quark a cleaner start by rejecting UV and IR energy to OD4 while passing about 97% of visible light on a quarter-wave B270 optic, helping your solar Ha imaging stay stable and sharp.