How can you tell if your solar viewer is
not safe? You shouldn't be able to see anything through a safe solar filter except the Sun itself or something comparably bright, such as the Sun reflected in a mirror, a sunglint off shiny metal, the hot filament of an unfrosted incandescent light bulb, a bright halogen light bulb, a bright-white LED bulb (including the flashlight on your smartphone), a bare compact fluorescent (CFL) bulb, or an arc-welding torch. All such sources (except perhaps the welding torch) should appear quite dim through a solar viewer. If you can see shaded lamps or other common household light fixtures (not bare bulbs) of more ordinary brightness through your eclipse glasses or handheld viewer, and you're not sure the product came from a reputable vendor, it’s no good. Safe solar filters produce a view of the Sun that is comfortably bright (like the full Moon), in focus, and surrounded by dark sky. If you glance at the Sun through your solar filter and find it uncomfortably bright, out of focus, and/or surrounded by a bright haze, it’s no good. You should contact the seller and demand a refund or credit for return of the product, then obtain a replacement from one of the sources listed on our
reputable-vendors page.
Remember that a genuinely safe solar viewer does more than reduce the Sun's visible light to a comfortable brightness level. It also blocks potentially harmful UV and IR radiation. The only way to tell whether your viewer does that is to be certain that it meets the ISO 12312-2 safety standard, and the only way to know
that is to be certain that it came from a reputable vendor.
