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
Blocking depth: OD4 (200nm-1100nm)