Experts Urge 3 DIY Eclipse Viewers as Glasses Shortage Leaves Safe Alternatives

Q: How could a quick snapshot of the eclipsed sun permanently destroy your smartphone camera before you even realize it?

Yes — even a seemingly quick photo can damage a smartphone camera because the phone’s lens concentrates sunlight onto a tiny image sensor, much like a magnifying glass focusing light onto one spot. During an eclipse, the danger remains because a partially covered Sun is still intensely bright, and that concentrated light and heat can overload or burn the sensor’s photodiodes. If those pixels are damaged, the harm is permanent: future photos may show black spots, streaks, blotches or dead pixels. In some cases, the camera module can also overheat enough to trigger the phone’s thermal shutdown, and repair can be costly. The risk rises sharply if the phone is pointed at the Sun for more than a brief moment, if video is recording continuously, if digital or optical zoom is used for a prolonged period, or if an external telephoto lens is attached. Experts note that one very quick shot may not always destroy a phone camera, especially on small smartphone sensors, but users often cannot tell when exposure has crossed into damaging territory until the defects appear later. That is why safety guidance treats any unfiltered phone camera as unsafe for eclipse viewing or filming. The recommended fix is a proper front-mounted solar filter that meets eclipse-safety standards, or better yet, indirect viewing methods such as a pinhole projector, tree-leaf projections, or a colander pattern on the ground. Improvised filters such as sunglasses, CDs or X-rays do not provide reliable protection.

Q: When is the exact, fleeting moment during a solar eclipse that taking off your protective glasses becomes completely safe?

It is safe to take off protective eclipse glasses only during totality — the brief moment when the Moon completely covers the Sun’s bright face — and only if you are inside the path of totality. That safe window begins immediately after the last direct sunlight disappears, often marked by the end of the “diamond ring” effect and Baily’s beads. At that instant, the Sun’s glaring disk is fully blocked and the corona becomes visible to the naked eye. The moment any bright sunlight reappears, you must put the glasses back on at once. If you are outside the path of totality, there is no safe moment to remove them while looking at the Sun, because some part of the solar surface remains visible throughout the eclipse. Even a tiny uncovered crescent can damage the retina. Experts stress that this is a fleeting and location-dependent moment. A deep partial eclipse is not enough. Unless the eclipse is truly total where you are standing, keep certified ISO 12312-2 eclipse glasses on for all direct viewing, or use indirect methods such as a pinhole projector, tree-leaf shadows, or a colander projection. For cameras, binoculars, and telescopes, separate certified solar filters are still required. Unfiltered optics are dangerous even if you are wearing eclipse glasses.

Q: Why might staring at the eclipse leave you with irreversible blind spots days later without you feeling any pain at all?

Staring at an eclipse can leave irreversible blind spots because the eye focuses the Sun’s intense visible and near-infrared light onto the macula, the part of the retina responsible for sharp central vision, where it can trigger solar retinopathy. The damage may not hurt because the retina has no pain receptors. People often assume they are safe because they feel no burn or immediate discomfort, but the injury is happening in the light-sensitive retinal cells, not on the pain-sensitive surface of the eye. During an eclipse, the dimmer surroundings can also suppress the normal urge to look away, making it easier to stare longer while the remaining crescent of Sun is still dangerously bright. Symptoms are often delayed because much of the injury is photochemical: intense light can set off harmful reactions in retinal cells and the supporting retinal pigment layer. That damage may only become noticeable hours or even days later, when people develop blurred vision, distortion, light sensitivity, or a central gray, yellow, or dark spot in their sight. Those blind spots can be permanent because retinal tissue does not reliably regenerate, and there is no proven treatment for solar retinopathy. That is why experts stress prevention: use certified ISO 12312-2 eclipse glasses for direct viewing, or safer indirect methods such as pinhole projection, tree-leaf shadows, or a colander. Ordinary sunglasses, CDs, X-rays, and other homemade filters are not safe.

2 articles · Updated · Futura · Aug 16

Hours before Wednesday’s solar eclipse, experts said people without protective glasses should watch only projected images of the Sun, not the Sun itself.
A simple pinhole setup—cardboard and white paper—or a foil-lined cardboard box can project the Sun’s disk and show it narrowing into a crescent as the eclipse advances.
Natural substitutes also work: gaps between tree leaves, interlaced fingers or a kitchen colander can create multiple pinhole projections when viewers keep their backs to the Sun.
Phones still need special solar filters, experts said, warning that unfiltered viewing can burn the retina and damage camera sensors; CDs, X-rays and stacked sunglasses are not safe substitutes.
The advice is aimed at a glasses shortage but remains useful beyond the eclipse, since the same projection methods can also reveal sunspots year-round.