Introduction: Cheap and Effective Filters (solar)

You can buy solar film (thin plastic sheets) at a very reasonable prices online. However, the sheet format isn't great for photography, telescopes or binoculars. You can by them as screw-on filters, but the cost gets a bit ridiculous and the size selection is limited.

This instructable is trivial, but that's where the beauty lies. Using cheap and readily available filter step-up adaptors and UV filters you can fit solar filters to your equipment.

  • Protects film from accidental scratches.
  • Wind protection to stop creases.
  • Holds filter flat and close to lens to stop internal light reflections that can create image artifacts.
  • Looks clean and professional.
  • Made using cheap and readily available parts.
  • Securely holds filters to reduce risk of them slipping and exposing your eyes to magnified UV.
    Important safety feature when using with telescopes or binoculars!
It is important to never scratch or crease the solar film since it might allow dangerous UV light to reach your eyes. If you mistakenly do so while following this instructable, don't try to salvage that section of film, just use a different piece.

This technique can also be used for colored gels!

Step 1: Materials

You'll need a few things you can get pretty cheaply.

  • A cheap, thin "step up ring adaptor".
    Used to attach larger filters to cameras. ($1.20 on ebay)
  • A cheap, thin UV filter. ($3 each on ebay).
    You don't really need the UV protection, you just want physical glass to protect the film.
  • High quality solar film.
    Do NOT go cheap here!!!! 8x8 on Amazon is $18, but it's enough to do a lot of filters. Also, you won't have to worry if you mess up the first attempt.

  • Clean, smooth surface that you can cut on.
    You will be sliding the filter film around on it and you don't want to scratch it. Non-corrugated cardboard, felt, or paper with cardboard under it.
  • Needle
  • Razor
  • Lens cleaning cloth

Again, do not buy solar film from unknown vendors. If you get sold something that isn't really cutting out the UV, then you will damage your eyes and not even realize it until it's too late. It's not as important with digital cameras that use LED screens, but anything involving your eyes and the quality becomes critically important.

Step 2: Step-up Ring Adaptor

What to buy a step-up ring adaptor that is meant to fit slightly larger filters onto your camera.

My camera is 72mm, it says right on the lens.

The step-up ring adaptor is so that I can put 77mm filters onto the camera.

The solar film fits in this buffer between 72mm and 77mm. The UV filter will fit the larger size (77mm) and will hold and protect the solar film in place.

Again, solar film protection is an important feature. If you're using the filter with a telescope or binoculars. You don't want any scratches or folds in the film and the glass UV filter is there to protect the solar film.

Step 3: Trace Solar Film

I experimented with a bunch of ways to cut the solar film and settled on one that works for me. Please suggest alternate ways to cut in the comment.

  1. Place solar film onto a large, thick piece of smooth cardboard or paper or felt cloth.
  2. Place the ring adaptor onto the solar film
  3. Use a needle to trace the outside (77mm) of the filter onto the film.
    Yes, this will be slightly too big

You can see in my second photo that I messed up a little, but that's ok because this circle is bigger than we need.

Step 4: Cut Solar Film

Now that you have a circle traced on the solar film, it's time to cut it.

You'll want to cut slightly inside the circle, but don't worry. There's room for error and if it will probably be too big the first iteration.

4. Place the edge of a sharp razor just inside the etched circle. It should dig into the cardboard under the film and say there.

5. Now move the film and leave the razor in place.
This is a similar action to using a bandsaw.

6. Slide the film around to cut out the circle.

Be careful to not scratch or crease the film.

7. Once you have the circle of film, see if it fit inside the adaptor ring (It probably won't).

8. Repeat the bandsaw technique to shave off a little around the outside until it does fit.

Step 5: Clean and Assemble

Final step is to place the solar film into the ring adaptor and screw on the UV filter.

Naturally, you should gently clean everything of dust first. Just be careful and DON'T use a strong blower on the filter, it will crease it.

Store your final filter in the UV filter case.


alzie made it! (author)2014-01-09

Great idea.

Also, consider the Baader solar film.

Ive used this stuff telescopically, and
it works very well.

trophygeek made it! (author)trophygeek2014-01-09

That site has a scary instructable for using cardboard and tape to "secure" filters onto a pair of binoculars. (PDF)

Would be nice if they updated it to use the technique I described here.

BTW, I put this instructable under a public domain license. Sites can either link to it or just create their own white paper based on it.

alzie made it! (author)alzie2014-01-09

Actually, the card board n tape method works pretty well.
You make a card board cup that
mates to your instrument with a friction fit.
Also, since youre looking Up at the sun,
gravity helps keep the filter on your instrument.
Ive made 2 of these,
one for my 3" refractor and
one for my 8" reflector.
The baader film works very well.

trophygeek made it! (author)trophygeek2014-01-09

Thanks! It's good to have choices since many sellers are perpetually out of stock.

My filter usage is with OLED viewfinder cameras, but I plan to do one for my telescope and am looking for a better source than Amazon.

Cometeer made it! (author)2014-01-08

This is one of the best solar films.

trophygeek made it! (author)trophygeek2014-01-08

Good to know! Thanks.

Cometeer made it! (author)Cometeer2014-01-08

Much better than the Thousand Oaks filter.

mattthegamer463 made it! (author)2014-11-27

This is great, and I managed to do this using some Thousand Oaks film bought on eBay and I am wondering if I got ripped off. My calculations show it blocks 1/67M of the light instead of 1/100k as it was specified to do. It's so dark you can't see anything through the viewfinder or holding the filter up and looking through by eye. This makes it really hard to aim it at the sun, and even then I was only getting an image when over 1 second, ISO 1600 and f6.3, which seems ridiculous to me. Could you post your typical camera aperture, shutter speed and ISO? Thanks.

trophygeek made it! (author)trophygeek2014-11-28

As soon as I can get a clear shot of the sun, I'll provide it.

mattthegamer463 made it! (author)mattthegamer4632014-11-28

I got the attached photograph today at ISO 800, F11 and 1/8s with a 400mm and 2x on a APS-C sony A300, so 1200mm equivalent telephoto.

DSC00309 (Custom).JPG
trophygeek made it! (author)trophygeek2014-12-02

OK. Too much rain here in SF to get a good shot of the sun, but I will try again soon. Forecast says maybe Sat.

I really recommend using cameras that don't have a "through the lens" eyepiece, but instead use an OLED screen just for eye protection.

Here are some older shots I took with my A77 using an IR filter only. Again, because it's OLED eyepiece it was safe. EXIF info is there.

My newer Sony A6000 camera has a "Full Spectrum" conversion which basically replaces the internal UV/IR cut filter with a clear filter. This means it picks up light well into the infrared part of the spectrum. I haven't tried it with the solar filter, but I'm curious to see how it behaves.

trophygeek made it! (author)trophygeek2014-12-02

OK. I found my original set of photos I took for this article.

This shot's information is:

Sony A77

ISO: 50
6.3F @ 1/13th

Focal Length: 250mm (using a Sigma 18-250mm lens)

mattthegamer463 made it! (author)mattthegamer4632014-12-02

Thanks for the info.

JTomM129 made it! (author)2014-02-14

I would aim for the true color filter solar material myself. And you can always sandwich two UV filters together to give the solar filter material more protection.

arikii made it! (author)2014-01-29

Of course, a micrometer and cnc laser cutter might be the most precise way to go about this, but this works great for those of us who don't have expensive laser equipment available to us...

HappyUndertaker made it! (author)2014-01-11

Why don't you pay attention to the huge spots on the sun?

chadn1 made it! (author)2014-01-10

Will this type of solar film work for viewing an eclipse?

trophygeek made it! (author)trophygeek2014-01-10

It's the same film and it works great for photography and this hack.

I plan to do it for my binoculars for the upcoming US solar eclipse in 2017.,_2017

It's a good idea to plan solar eclipse trips a couple of years in advance.

chadn1 made it! (author)chadn12014-01-10

Thanks, I am already making plans. Come to Grand Island, Nebraska to see the eclipse. likely to have clear weather that time of year and time of day. That is why I was asking.

trophygeek made it! (author)trophygeek2014-01-10

Oh, and some other comments below list sights that have high-quality solar filter sheets. You might want to check them out.

maewert made it! (author)2014-01-09

When I was a kid, in accordance with the astronomy books at the time, I 'smoked' a glass plate by placing the glass plate over a candle's flame and moving it around until the soot was dark and uniform.... my goodness, I'm lucky I still have any eyesight left.

Nice instructable and much more safe!

trophygeek made it! (author)trophygeek2014-01-10

Yikes! Yeah, I had a "wood burning kit" as a kit that was nothing more than a soldering iron. Your story makes that sound downright safe.

I was in China for the 2009 solar eclipse and the "solar viewing glasses" that street vendors were selling would damage people's eye. Their culture (at the time) was very much buyer-beware. Good thing is was clouded over for most of the country.

gingertux made it! (author)2014-01-10

You can use a good set of scissors to cut the solar film out. If you are using corrugated cardboard, the change in density between corrugations can cause the razor blade to slip and give an irregular edge. Also not as safe.

trophygeek made it! (author)trophygeek2014-01-10

Yeah. I suggested felt fabric and when I said cardboard, I was thinking non-corrugated. I'll update the instructable to be more clear.

High quality scissors can be used, but I always struggled to not crinkle the solar film while handling it. Placing it on flat surface seemed to work better for me. But I don't have a lot of scissor cutting experience.

AngryRedhead made it! (author)2014-01-07

Clever, fellar!

trophygeek made it! (author)trophygeek2014-01-07


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