ERF-prefilter E-150N100 for H-alpha solar monitoring | DayStar

Without a pre-filter, too much heat ends up in the narrow H-alpha filter at the rear with larger apertures. The DayStar ERF E-150N100 for the aperture solves this problem. The filter blocks ultraviolet and infrared light and allows the red light to pass through, which is what the H-alpha filter works with.

Which ERF you need depends on the opening and the outer diameter of your telescope. You can find the other sizes and separate filters at our website. solar filters for telescopes. If you are unsure about choosing between two sizes, please compare them. the ERF pre-filter E-130N100.

Measure the outer diameter of your tube or watering can and compare it with the specified size of the container. Then, don't aim your telescope at the sun by chance, but use a solar viewfinder with projection, So that you never have to look through an unfiltered viewfinder. An ERF itself is not a solar filter to use for viewing, so never look at the sun without the full filter setup.