what filter to use for solar eclipse
You must use a proper solar filter that is specifically rated for direct Sun / eclipse viewing or very high‑stop ND filters designed for solar imaging.
Absolute safety rules
- Never look at the Sun with the naked eye, sunglasses, camera viewfinder, or through an un‑rated filter (including regular ND, polarizers, welding glass below shade 14, smoked glass, CDs, etc.). Serious and permanent eye damage is possible.
- Only very short moments during totality (when the Sun is completely covered) are safe without a filter, and only if you are 100% sure you are in the path of totality and know the timing. The filter must go back on as soon as the first bright sliver returns.
For your eyes (visual viewing)
Use one of these:
- Certified eclipse glasses or handheld viewers
- Must be labeled with ISO 12312‑2 (the international safety standard for direct solar viewing).
* Buy only from reputable astronomy/optics sellers or lists recommended by big science orgs (NASA, AAS, recognized astro retailers).
- Solar viewing film in a frame
- Made from genuine solar film (e.g., “black polymer” or AstroSolar‑type film) mounted in cardboard or plastic frames.
* Designed to dim the Sun by around 100,000× (optical density ≈ 5), so it looks comfortably dim and orange/white.
Do not rely on DIY hacks unless you are using real solar film from a reputable astronomy source and following their instructions exactly.
For camera / telescope / binoculars
You need a front‑mounted solar filter that covers the objective (the front glass), not just a small filter on the eyepiece.
Best options
- Full‑aperture solar filter (film or glass)
- Commercial filters made for telescopes, binoculars, and camera lenses; many use special solar film or coated glass.
* They typically provide **OD 5** (≈ 16–17 stops or more) attenuation and are rated “safe for direct solar imaging.”
* Example categories: “universal solar filter”, “white‑light solar filter”, “solar filter for camera lens.”
- DIY filter using solar film
- Use certified solar film sheets from an astronomy supplier and mount them over a rigid ring or cardboard cell that fits snugly over your lens/telescope.
* Film must be free of pinholes, creases, or scratches; discard damaged pieces.
High‑stop ND filters (for cameras only)
- Some manufacturers sell 15‑stop to 20‑stop ND filters specifically advertised as safe for solar imaging (e.g., Kolari Pro 15‑ or 20‑stop, Hoya ND100000).
- Important limitations:
- These may be safe for the camera sensor but not certified for your eyes. You must compose using live view or an electronic viewfinder , never through an optical viewfinder.
* “Regular” 3–10 stop ND filters (the kind used for waterfalls, etc.) are not strong enough for the Sun on their own.
Simple guidance by goal
If you just want to watch the eclipse
- Get ISO 12312‑2 eclipse glasses or a certified handheld viewer.
- Keep them on whenever any part of the bright Sun is visible (partial, annular, or before/after totality).
If you want to take photos with a camera
- Safest: a front‑mounted solar filter (film or glass) sized for your lens, advertised specifically for solar eclipse / solar photography.
- Alternative: a 15–20 stop ND filter that the manufacturer explicitly rates for solar imaging, and use only live view / EVF.
Quick reference table
| Use case | Filter type | Key requirement |
|---|---|---|
| Looking with your eyes | Eclipse glasses / handheld viewer | Must be ISO 12312-2 certified, from reputable seller. | [9]
| Camera, telescope, binoculars | Front-mounted solar filter (film or glass) | Optical density ≈ 5, sold specifically for solar viewing/imaging. | [2][7][9]
| Camera only, screw-on filter | 15–20 stop ND filter rated for solar | Safe for sensor; use only live view/EVF, not optical viewfinder. | [1][3][7]
Bottom note
Information gathered from public forums or data available on the internet and portrayed here.