What the standard defines
ISO 12312 covers eye and face protection for sunglasses and related eyewear, and its second part deals specifically with filters intended for direct observation of the Sun — the situation an eclipse creates, where people who would never otherwise look at the Sun intend to do exactly that.
It is the document that eclipse glasses listings cite, and it is a requirements standard rather than a designation: it exists so that a filter made for this purpose can be assessed against stated criteria rather than against a claim.
What it fixes is the requirements for that class of filter. Manufacturers who make such products publish a declaration referring to it, and they supply instructions with the product covering inspection, use and storage.
What it does not promise
It does not extend to optical instruments. The filters in scope are for the unaided eye, and a telescope, binocular or camera is a separate situation with separate products made for it — a full-aperture filter fitted in front of the instrument, with its own instructions.
A citation in a listing is not itself an assessment. Anyone can type a standard number into a product description, which is why the manufacturer’s identity printed on the product matters as much as the number does.
And the standard does not replace the maker’s instructions. Inspection before use, storage between uses and any stated service life come from the manufacturer, and this site points to them rather than restating them.
What it works with
The standard sits alongside the products made for looking at the Sun directly, and alongside the separate category of filters made to go in front of a telescope, which follow their own makers’ specifications and instructions.
On this site it appears on eclipse glasses and, by adjacency, on full-aperture solar filters — where every page defers to what the manufacturer publishes rather than offering a judgement of its own.
The questions that keep arriving
Do eclipse glasses that cite this standard work with a telescope?
No, and every maker says so on the packet. These are filters for the unaided eye. A telescope, a pair of binoculars or a camera lens concentrates light before it reaches a filter held at the eye, and the products on this shelf are not made for that situation. Follow the instructions supplied with them.
How do I know a listing’s claim is genuine?
Look for the manufacturer’s name and address printed on the product itself rather than only on the packaging, and for the standard printed there too. An unattributed pair is an unanswerable question, and this site says so on every page where it applies.
Do these filters expire?
The makers publish their own guidance on storage, inspection and service life, and it differs between products. That guidance is part of the product, and it is what this site points to rather than paraphrasing.
Last reviewed 17 September 2026