Ensuring Safety with Eclipse Glasses and Solar Viewers
When preparing to view a solar eclipse, it’s crucial to ensure your eclipse glasses or handheld solar viewers are safe. This means they should comply with the ISO 12312-2 international safety standard, which guarantees they significantly reduce visible sunlight and effectively block harmful solar UV and IR radiation.
Verifying ISO 12312-2 compliance isn’t something you can do at home—it requires a spectrophotometer, a sophisticated device used by accredited labs to test the filter’s ability to block intense UV, visible, and IR light. Manufacturers must have their products tested by these labs to confirm adherence to safety standards and to legitimately claim ISO compliance on their products and packaging.
Beware of deceitful sellers who might illegitimately use the ISO logo. Authenticity comes from purchasing from reputable manufacturers or authorized dealers. The American Astronomical Society (AAS) Solar Eclipse Task Force diligently verifies vendors, listing approved suppliers of safe solar filters and viewers on their website. They ensure these vendors have proper ISO documentation from accredited labs and have undergone product inspection.
If a supplier isn’t listed, it doesn’t imply their products are unsafe. The challenge is the vast number of retail and online sources available, making it impossible to list them all. However, listed suppliers are verified for safety.
Identifying Unsafe Solar Viewers
A safe solar viewer allows you to see only the Sun or similarly intense light sources, which should appear dim. If you can see less intense light sources, or if the Sun appears too bright, out of focus, or surrounded by a bright haze, the viewer may be unsafe. In such cases, contact the seller for a refund or replacement from an approved source.
Remember, genuine safety means more than just reducing visible light; it includes blocking harmful UV and IR rays. The only way to ensure this is by using products from reputable sources that meet the ISO 12312-2 standard.
Considerations for Received or Gifted Viewers
Eclipse glasses or viewers received from astronomers, professional organizations, or reputable events like science museums or astronomy trade shows are likely safe, assuming they trace back to a trusted vendor.
What to Avoid
Do not rely on ordinary sunglasses, homemade filters, or inadequate welding filters for viewing the eclipse. Only welding filters of Shade 12 or higher are safe for direct solar viewing. Lesser shades, homemade, or non-specialized filters may not protect against the full spectrum of solar radiation, posing risks to your eyesight.
Usage and Maintenance of Eclipse Viewers
ISO 12312-2 compliant glasses or viewers can be used to view the uneclipsed or partially eclipsed Sun indefinitely if they are undamaged and securely attached to their frames. Ignore warnings about limited viewing times and expiration dates that don’t apply to ISO-compliant products. However, never use these viewers with telescopes, binoculars, or other optical devices.
By prioritizing safety and choosing the right equipment, you can enjoy the solar eclipse without risking your vision. Always source your viewing gear from reputable suppliers and ensure it meets established safety standards
