Total Eclipse of the Heart. Strap this Celestron EclipSmart Solar Filter for 6-inch SCTs to the front of your Celestron NexStar for safe viewing of the sun, eclipses, and sunspots. A Solar Safe film designed for this filter protects your and your telescope, and conforms to the ISO 12312-2:2015(E) international safety standard for filters. This filter attaches to the NexStar with included hook-and-loop straps.