Uploaded March 2024 | Updated September 2026, 2 hours ago
Viewing a solar eclipse can be the experience of a lifetime, but you should only directly view the sun when using approved solar viewing glasses.
Solar viewing glasses reduce the brightness from the sun to safe levels for viewing. In photonics, light reduction is called 'attenuation' and the optical density ("OD") defines by how much.
Optical density is a logarithmic value that represents how many powers of 10, the incident light will be reduced.
To meet safety requirements, solar viewing glasses must meet the ISO 12312-2 standard. The ISO 12312-2 standard defines a maximum transmittance of 0.0032% in the UV and visible ranges (280-780 nm). In the IR(780-2000 nm), the maximum transmittance is much higher, at 3%. These transmittances calculate to minimum optical densities of 4.5 in the UV and visible, and 1.53 in the IR.
While all ISO certified solar viewing glasses should have an ISO stamp on them, this does not guarantee they're certified. Safety viewing glasses should only be purchased from trustworthy suppliers. For approved suppliers, the American Astronomical Society provides a consolidated list. eclipse.aas.org/eye-safety/viewers-filters
Viewing a solar eclipse can be the experience of a lifetime, but you should only directly view the sun when using approved solar viewing glasses.
Solar viewing glasses reduce the brightness from the sun to safe levels for viewing. In photonics, light reduction is called 'attenuation' and the optical density ("OD") defines by how much.
Optical density is a logarithmic value that represents how many powers of 10, the incident light will be reduced.
To meet safety requirements, solar viewing glasses must meet the ISO 12312-2 standard. The ISO 12312-2 standard defines a maximum transmittance of 0.0032% in the UV and visible ranges (280-780 nm). In the IR(780-2000 nm), the maximum transmittance is much higher, at 3%. These transmittances calculate to minimum optical densities of 4.5 in the UV and visible, and 1.53 in the IR.
While all ISO certified solar viewing glasses should have an ISO stamp on them, this does not guarantee they're certified. Safety viewing glasses should only be purchased from trustworthy suppliers. For approved suppliers, the American Astronomical Society provides a consolidated list. eclipse.aas.org/eye-safety/viewers-filters
