Player One ERF 2" Energy Rejection Filter

Overview. The Player One ERF 2" Energy Rejection Filter is an S-series pre-filter designed to remove excess infrared and ultraviolet energy ahead of a Ha etalon system such as the Daystar Quark Chromosphere. By transmitting the visible band while rejecting IR and UV, it reduces the heat load on the etalon and improves image contrast and stability. The filter uses a B270 optical glass substrate with a multi-layer composite coating and threads into 2" mounts.

Who It's For. This filter suits solar imagers running a Quark Chromosphere (Ha) or similar etalon that benefits from an energy-rejection pre-filter, as well as imagers seeking a broadband IR/UV-cut for high-contrast lunar work.

Key Features & Design.

• Wide IR/UV rejection: OD4 blocking across 200–1100nm removes ultraviolet and infrared energy that would otherwise reach the etalon.
• High visible throughput: approximately 97% transmittance in the passband preserves brightness for the Ha system.
• Roughly 60nm passband: transmits the visible band needed by the downstream etalon.
• B270 optical glass: a stable, transparent substrate with a multi-layer composite coating.
• 2" format: M48×0.75 threads for standard 2" holders ahead of the Ha unit.

Optical/Mechanical Design. The filter transmits an approximately 60nm visible passband at about 97% peak transmittance while blocking to OD4 across 200–1100nm, rejecting both ultraviolet and infrared. The B270 transparent glass element is 2.5mm thick and figured to 1/4 lambda, carrying a multi-layer composite coating. The anodized cell uses M48×0.75 (2") threads and measures 7.5mm overall (5mm body plus 2.5mm thread).

Recommended Uses. Energy-rejection pre-filtering ahead of a Quark Chromosphere (Ha) or comparable etalon to lower heat load and raise contrast; broadband IR/UV-cut for high-contrast lunar imaging.

Compatibility & Accessory Notes. The M48×0.75 cell fits standard 2" threaded holders positioned ahead of the Ha system. It is intended as an energy-rejection pre-filter for the Quark Chromosphere Ha version and for lunar imaging. Note that this filter is not a solar white-light safety filter and must not be used on an eyepiece for direct visual solar observing.

Good to Know Before You Order.

• Intended placement: the ERF is used as a pre-filter ahead of a Ha etalon, not as a standalone visual solar filter.
• Not for eyepiece observing: do not use this filter on an eyepiece for direct solar viewing.
• Shipping weight: a packaged weight is not published by the manufacturer; contact us if you need it before ordering.

FAQ.

Is it difficult to set up? No. The filter threads into a standard 2" holder ahead of your Ha system and requires no adjustment once installed.

What does an ERF do? It rejects infrared and ultraviolet energy before it reaches the etalon, lowering heat load and improving contrast and image stability.

Can I use it for lunar imaging? Yes. Its broad IR/UV-cut passband also makes it suitable as a high-contrast filter for lunar imaging.

Bottom Line. A high-transmission B270 energy-rejection filter in the 2" format, the Player One ERF 2" protects and sharpens a Ha etalon setup and doubles as a capable IR/UV-cut for lunar imaging.