Looking at the Sun is usually a bad idea. Over the weekend I chatted with an optometrist, and he made it clear that permanent damage can be done to your eyes even if you don’t feel any pain. Safe ways to observe the solar eclipse include making a pinhole projector or simply wearing eclipse glasses. While I haven’t found any eclipse glasses that seemed unsuitable, the American Astronomical Society recommends five manufacturers: American Paper Optics, Baader Planetarium (AstroSolar Silver/Gold film only), Rainbow Symphony, Thousand Oaks Optical, and TSE 17.
Here I am wearing sunglasses and eclipse glasses. I was testing a solar filter I had constructed for a DSLR camera using a solar filter sheet.
Eclipse glasses serve as neutral density filters that block 99.99% of light coming from anywhere. The only thing bright enough to be seen through them is the Sun. Although they are called “eclipse glasses,” you can look at the Sun through them on any day of the year. Eclipses are just the time it’s most tempting to direct your eyes toward that fiery ball. Sunglasses do not block enough light for safe direct solar viewing. We use sunglasses on a day-to-day basis because we want to see what’s around us while reducing the amount of sunlight reaching our eyes indirectly. If you experience the total eclipse, only during totality is it safe to look at the Sun without protection. Use eclipse glasses at all other times.