ERF pre-filter E-244F63 for 8 inch Schmidt-Cassegrain, H-alpha | DayStar

If you have an 8-inch Schmidt-Cassegrain telescope and want to view the Sun in H-alpha light, the heat must be kept away from the front of the telescope. The DayStar ERF E-244F63 is designed for this type of telescope. It blocks ultraviolet and infrared light and allows the red light through, where the H-alpha filter works, so there is much less heat going into the tube.

Think of a Celestron C8 on an AVX mount or another 8 inch from our Schmidt-Cassegrain telescopes. Check the outer diameter of the front of your tube or mist cap and compare it with the specified size.

The mount must fit snugly, without gaps where unfiltered sunlight can pass through. An ERF is not a solar filter to look at by itself. Use it only in conjunction with a suitable H-alpha filter and never look at the sun without the full filter setup. Also remove the viewfinder from your telescope or cover it, and focus with a universal solar finder.