AAS Says ISO Labels Alone Cannot Verify Eclipse Glasses

An ISO 12312-2 claim or a familiar manufacturer’s name printed on eclipse glasses does not, by itself, establish that the viewer is safe. The American Astronomical Society advises obtaining viewers directly from a manufacturer on its vetted suppliers list or from an authorized reseller identified by that manufacturer. Torn, scratched, punctured, loose or otherwise questionable viewers should be discarded. If verified replacements are unavailable, viewers should observe the Sun indirectly through pinhole projection instead.

That sourcing check matters because counterfeit products can copy the name of a legitimate manufacturer. Consumers generally cannot verify the invisible-light performance of a solar filter by inspecting it, and an ISO statement can simply be printed on packaging. The AAS says testing by a properly accredited laboratory is what establishes conformity, making a traceable seller not merely the wording on the glasses the practical verification available to buyers.

The guidance received renewed attention around the Aug. 12, 2026, solar eclipse. The event produced totality in parts of Europe and other northern regions but appeared only as a partial eclipse across portions of the United States, including areas in 26 states and Washington, D.C. Alaska had been expected to see more than 20% maximum coverage, while parts of New England and New York were expected to see between 10% and 20%.

Those relatively modest percentages did not make direct viewing safe. In a partial eclipse, the Moon passes between Earth and the Sun without covering the Sun’s entire bright face. There is no total phase during which direct viewing becomes permissible. Proper solar eye protection is required throughout the event.

Why appearance is an incomplete safety check

A genuine solar viewer must control more than visible brightness. It also has to block potentially harmful ultraviolet and infrared radiation, which people cannot assess by looking through the filter. A viewer that makes the Sun appear comfortably dim is therefore not automatically proven safe.

The AAS provides simple checks that can identify an obviously inadequate viewer. Indoors, users should not be able to see furnishings, wall art or other ordinary objects through the filter. Outside, nearly everything should remain invisible except perhaps an extremely faint reflection of the Sun. These checks can show that a viewer is not dark enough, but passing them still does not replace verified laboratory testing and traceable sourcing.

Physical condition is another firm rejection criterion. A scratch, puncture or tear can compromise the filter, while a filter separating from its cardboard or plastic frame may no longer cover the user’s eyes reliably. NASA’s eclipse-viewing guidance likewise says damaged viewers should be discarded and children should be supervised when using solar filters.

Cameras and binoculars need their own filters

Eclipse glasses are designed for direct viewing with the unaided eye. They must not be used as a substitute for a purpose-built filter on a camera, telescope or pair of binoculars. Those optical systems collect and concentrate sunlight, increasing the risk of serious eye injury and potentially damaging an eclipse-glasses filter placed between the instrument and the observer.

NASA says optical equipment requires the correct solar filter secured over the front, Sun-facing end of the optics. It also recommends seeking expert advice before fitting a filter to a camera, telescope or binoculars. Wearing eclipse glasses while looking through an otherwise unfiltered instrument does not provide the required protection.

Indirect projection avoids looking at the Sun altogether. With the Sun behind the observer, a small opening can project an image onto another surface; the projected image, not the Sun or the opening, is what the observer watches. Gaps between crossed fingers, holes in a colander or spaces between leaves can produce multiple projected crescents during a partial eclipse.

The Aug. 12 event has passed, but the purchasing test remains useful for future eclipses: verify the seller’s chain back to a vetted manufacturer, reject damaged or uncertain filters, and do not treat printed compliance language as proof. If that chain cannot be established, projection is the safer viewing method.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.