ND Filter Stacking Question: I just booked a trip to see the Solar Eclipse in 2024. I know that I will need adequate filters to shoot the sun (I think I've read that about 16 stops is...

KenProspero

I just booked a trip to see the Solar Eclipse in 2024.

I know that I will need adequate filters to shoot the sun (I think I've read that about 16 stops is what I need).

Shopping around a bit -- I can order a 16.5 stop filter (made for the purpose), or I can order a set of ND Filters (10,6,3 stops or 9,6,3 are common) for about the same money.

My understanding is that by stacking a 10 and a 6 stop filter, I create a 16 stop filter. If so, it seems that the 16.5 stop filter is only good for shooting the sun, while the set of filters provides flexibility.

FWIW -- I'll be shooting with a Sigma contemporary 100-400mm (at 400mm) for the eclipse. My Nikon Z 24-200mm lens takes the same size filters, so I'll have a reasonable wide angle lens if I get the set.

rmalarz Loc: Tempe, Arizona

Stacking can cause issues with intersurface reflections. I'd minimize the number of filters when shooting sun or moon.
--Bob

KenProspero wrote:

I just booked a trip to see the Solar Eclipse in 2... (show quote)

CHG_CANON Loc: the Windy City

Buy the proper filter for eclipse photography. With 2 years to go, you might find some used copies as the demand is down from the last big event.

As a reminder of not using the proper filter: https://www.lensrentals.com/blog/2017/09/rental-camera-gear-destroyed-by-the-solar-eclipse-of-2017/

Architect1776 Loc: In my mind

KenProspero wrote:

I just booked a trip to see the Solar Eclipse in 2... (show quote)

Far better to just get a solar filter.
Not expensive and does the job perfectly.

amfoto1 Loc: San Jose, Calif. USA

For many things, I wouldn't hesitate to stack a couple ND filters (so long as they are top quality, multi-coated).

BUT a solar eclipse is DEFINITELY not when I'd use a stack. I would definitely get the specific filter for that purpose. That will be the safest for my camera and my eyes.

PoppieJ Loc: North Georgia

Thousand Oaks sells all sizes of solar filters and if you don't want to pay the price (quite reasonable) then they also sell sheets of solar filter paper and you can buy a sheet and use it for multiple lenses

Orphoto Loc: Oregon

Solar filters knock out more than just neutral density. Another vote for safety. (and then during the eclipse don't forget to remove the filter)

flyboy61 Loc: The Great American Desert

One thing to be aware of when stacking filters, other than adding reflective surfaces to a lens is not a good practice. Each filter
moves the focus point in the camera about 25% of the filter's thickness. More would just compound the problem, it seems to me.

rmalarz Loc: Tempe, Arizona

Can you cite a reference for this? I’d be interested in looking more closely at this anomaly.
-Bob

flyboy61 wrote:

One thing to be aware of when stacking filters, other than adding reflective surfaces to a lens is not a good practice. Each filter
moves the focus point in the camera about 25% of the filter's thickness. More would just compound the problem, it seems to me.

GLSmith Loc: Tampa, Fl

First Question:...How much do you value your eyesite?...Go out and read what happens to your eyes if you use the incorrect filter....Use a solar filter, nothing less. There are several good ones with a budget that will not break the bank. Numerous articles also written on what will happen to the sensor on your camera in shooting solar eclipses if incorrect filters are used.

CaptainPhoto

Right. I bought the filter for the last eclipse and also the sheet. I ended up using the sheet. It worked just fine. The sheet over my lens hood and a rubber band did the trick just fine.

jackpinoh Loc: Kettering, OH 45419

You will encounter significant vignetting when you stack three filters.

petrochemist Loc: UK

amfoto1 wrote:

For many things, I wouldn't hesitate to stack a couple ND filters (so long as they are top quality, multi-coated).

BUT a solar eclipse is DEFINITELY not when I'd use a stack. I would definitely get the specific filter for that purpose. That will be the safest for my camera and my eyes.

100%! Normal ND filters have minimal effect on IR and may not hold back UV to the rated extent either. Both of these types of radiation are invisible to the eye but can do serious damage.

If you'd rather not splash out on proper solar viewing filters the affordable safe option is welding glass, but this typically introduces distortions that will degrade you images. Shade 13 is roughly 17 stops and worked out OK, if a bit soft, for photographing sun spots on my DSLR ~10 years ago.

flyboy61 Loc: The Great American Desert

rmalarz wrote:

Can you cite a reference for this? I’d be interested in looking more closely at this anomaly.
-Bob

Unfortunately, I can't...I think it was in a photozine several decades ago, and I've not seen it mentioned again. It sounded reasonable, and iirc, had some sort of attribution. Of course, information in magazines of that era was supposedly more accurate(?

) but what did we know, just starting out in photography, 'way back then?

Maybe Google will be our friend.

petrochemist Loc: UK

flyboy61 wrote:

One thing to be aware of when stacking filters, other than adding reflective surfaces to a lens is not a good practice. Each filter
moves the focus point in the camera about 25% of the filter's thickness. More would just compound the problem, it seems to me.

This shift in focus applies to glass behind the lens, but not to glass in front where the rays are typically parallel.
It's quite commonly seen with full spectrum conversions if the original hot mirror is not replaced.