ERF-prefilter E-200N150 for H-alpha solar monitoring | DayStar

A DayStar Quark or other H-alpha filter on a telescope with a large aperture will have to process a lot of heat without a pre-filter. Therefore, you should place the DayStar ERF E-200N150 in front of the telescope aperture. The filter blocks most of the ultraviolet and infrared light and lets through mostly red light, so the H-alpha filter stays protected at the rear.

The filter fits either the tube or the dew cap, provided the fitting matches the outer diameter. All sizes and other filters for the sun are available from our sunwatch filters.

Measure the outside diameter in advance and contact us if in doubt. Never look at the sun with an ERF alone. Use the filter only as part of a complete H-alpha setup, as intended. For smaller openings, it is sometimes a UV/IR blocking filter in 2 inch an option, but first get advice about it, because it depends on the opening and the type of telescope.