Player One


Player One S-Series 1.25 inch ERF Filter - Dark Clear Skies


Tax included. Shipping calculated at checkout.


Generally In Stock, Please Confirm Before Ordering

Player One S-Series 1.25 inch ERF Filter


Category: Filter and Wheel


The Player One S-Series 1.25 inch ERF Filter utilizes high-quality optical glass substrate and multi-layer composite coating technology, ensuring excellent optical performance for astrophotography.

The ERF filter is an assistant filter specifically designed for the Quark Chromosphere (Ha version). Its purpose is to reject excess energy and extend the lifetime of your Quark. This 1.25 inch ERF filter is suitable for use on refractors with a diameter of 5 inches or smaller. Please note that it is not intended for use with eyepieces for visual observation.

Why add an ERF on Quark? The first filter on the Quark is relatively small, and the solar disk may be larger than the filter, causing heat to build up on the filter and its holder. By using the 1.25 inch ERF filter, you can protect both the filter and its holder from high temperatures. The ERF filter itself is made of B270 transparent glass and features multi-coating, allowing it to reflect rather than absorb most of the energy.

Additionally, the ERF filter can also be used in lunar imaging, providing a brighter image compared to an IR685 filter and potentially improving the overall seeing conditions.


  • Filter Size: 1.25 inch
  • Thread: M28.5*0.6
  • Frame Thickness: Body 5mm + Thread 2.5mm, total of 7.5mm
  • Thickness of Filter Lens: 2.5mm
  • PV (Peak-to-Valley): 1/4 lambda
  • Transmittance: ≈97%
  • Blocking Depth: OD4 (200nm-1100nm)

1.25inch ERF filter ( Energy rejection filter for Quark Chromosphere)

This filter is an assistant filter, design for Quark Chromosphere (Ha verstion) , intended to reject energy and extend the life time of your Quark.

1.25″ ERF filter only to be used on 5″ or smaller refractors.

(DO NOT use it on eyepiece for observing)

Why add a ERF on Quark?

First filter on Quark is quite small, the solar disk might bigger than it, the light will heat the filter and it’s holder. With this 1.25″ ERF filter, we can protect both the filter and filter holder from high temperature.

And don’t worry about the ERF itself, it’s use B270 transparent glass and multi coating, it will reflect not absort most energy.


Does it has any other usage?

Yes, this ERF filter also can be used in Lunar imaging, it will provide even brighter image than IR685 filter, also could improving the seeing.

Specifications: 1.25 inch, thread M28.5*0.6

Frame thickness: body 5mm+ thread 2.5mm, a total of 7.5mm

Thickness of filter lens: 2.5mm

PV: 1/4 lambda

Transmittance: ≈97%

Blocking depth: OD4 (200nm-1100nm)


Player One S-Series 1.25 inch ERF Filter - Dark Clear Skies