dpullum Loc: Tampa Florida

SOLAR FILTERS FOR CAMERAS

There is an official ISO certification For reference, "a filter with a transmittance of 0.001% passes 1 part in 105 (100,000) of the incident light and is said to have an optical density (OD) of 5." The Eclipse ISO, International Organization for Standardization, is explained in detail here:
https://eclipse.aas.org/eye-safety/iso12312-2

In a search for a reasonably priced filter, it appears that TEMU is a good source. I have had good luck ordering from TEMU and they accept free shipping returns. Shipping is about two weeks, they accept PayPal.

To Find the solar filters on the TEMU.Com site consider the following: Not unusual, for a description to be word translation confusing… The TEMU search description you need is: “SLR For Camera/micro Single UV Filters Cover Solar Film Camera Lens End Astronomical Solar Sunspots Film Photography. “ Using that as a search criterion a series of images for viewing will appear on the results page. The upper left image is the one showing a DSLR, 5 filters, and $10.48... click on that to narrow in on solar Astro filters.

The description refers to the ISO certification. There is a wide range of screw filters available 52-82, $1048-16.48. The price is very reasonable compared to other sources.

dpullum Loc: Tampa Florida

Lots of discussion of this topic in the Main Photo section.

JohnSwanda Loc: San Francisco

What does this filter do for IR photography?

dpullum Loc: Tampa Florida

John, Last time I checked, the sun was very hot, and without filtering direct sun viewing would fry the camera's sensor. "About 40 percent of the solar radiation received at the earth’s surface on clear days is visible radiation within the spectral range 0.4 to 0.7 μm, while 51 percent of solar radiation is infrared radiation in the spectral region 0.7 to 4 μm."
https://www.sciencedirect.com/topics/chemistry/solar-radiation

IR cameras, especially full spectra, will see the sun differently from a "regular" visible spectra camera. For either, solar filters are needed to protect the camera's sensor.
https://www.kentfaith.com/blog/article_what-lens-filter-do-i-need-for-a-solar-eclipse_7431

dpullum Loc: Tampa Florida

"What lens filter do I need for a solar eclipse? The answer is an infrared filter. An infrared filter is a type of filter that blocks out visible light and allows only infrared light to pass through. This is important for viewing a solar eclipse because looking directly at the sun can cause permanent eye damage. An infrared filter will protect your eyes from harmful rays while still allowing you to see the eclipse.

It is important to note that not all infrared filters are created equal. Some filters may not be strong enough to protect your eyes from the intense light of a solar eclipse. It is recommended to use a filter specifically designed for solar viewing, such as a solar filter or eclipse glasses. These filters are made with special materials that block out harmful rays and allow you to safely view the eclipse." Sectgion 4:
https://www.kentfaith.com/blog/article_what-lens-filter-do-i-need-for-a-solar-eclipse_7431

petrochemist Loc: UK

You need to be rather careful going by optical density (or transmission/stops etc) as these measurements are usually only made with visual light.
Most ND type filters pass NIR quite readily above ~750nm. I've tested several weak ND filters (mainly just 1 or 2 stop) and found they transmitted ~95% of the IR wavelengths the spectrometer at work is sensitive to (700-1100nm) I see no reason to think they would not also transmit longer wavelength IR...

For viewing eclipses without splashing out on special solar filters, you can use welding glass - shade 8 is around 10 stops apparently the recommended minimum for direct viewing. Welding glass is specified to absorb UV & IR more than visual light so is safe.