Safe sun viewing with welding filter question

[Krupski]

Gentlemen,

I want to buy a plate of that ultra dark green glass that's used in arc welding helmets to view the sun (specifically the upcoming eclipse).

They come in various numbers... the higher the number, the darker.

Does anyone know what number filter I need to safely look at the sun (going for worst case... full noon sunlight on a clear day)?

I already have a #10 filter from a long time ago. It's pretty dark (I can barely see a 100 watt light bulb through it), but I'm guessing this isn't good enough for full blast sunlight.

Any suggestions or info will be appreciated! Thanks!

-- Roger

[l921428x]

Your right. A number 10 was not dark enough for me to weld without bothering my eyes, I used a 12.
A minimum of 14 is what you need. The easy way is to use the 10 and buy a 5 lens. 5's are used for oxy/acet
cutting torches and are available anywhere. Just tape them together and if you are still uncomfortable where sunglasses.
But no less than 15 for me and mine is set up already.

[alismith]

While not directly looking at the sun with filters, etc., an easy way to see what's going on it to take two index cards and, using a pin, punch a hole in the center of one of them. Now, turn so the sun in behind you and hold both index cards so the one with the pin hole is in one hand and the other card is in your other hand.

Make sure the pin hole card is between you and the other card. Line them up so there is a small dot on the unaltered card (the small dot is the sunlight passing through the hole). Now, when the eclipse starts you'll notice the dot is being "eclipsed," too.

You can watch the whole eclipse by looking at the dot on the unaltered index card. (Up to a point, you can move the cards closer to each other, or farther away from each other, to "focus" the image.)

The best thing about this little set up is that it's perfectly safe to your vision and you are still able to see what's happening.

[kuntryboy]

some years ago several of us tried using welding hoods to view a partial eclipse. even with cutting goggles under the hoods, it was not easy on the eyes. be careful.

[Helen Keller]

While not directly looking at the sun with filters, etc., an easy way to see what's going on it to take two index cards and, using a pin, punch a hole in the center of one of them. Now, turn so the sun in behind you and hold both index cards so the one with the pin hole is in one hand and the other card is in your other hand.

Make sure the pin hole card is between you and the other card. Line them up so there is a small dot on the unaltered card (the small dot is the sunlight passing through the hole). Now, when the eclipse starts you'll notice the dot is being "eclipsed," too.

You can watch the whole eclipse by looking at the dot on the unaltered index card. (Up to a point, you can move the cards closer to each other, or farther away from each other, to "focus" the image.)

The best thing about this little set up is that it's perfectly safe to your vision and you are still able to see what's happening.

did that for an eclipse back in '95 was pretty interesting how it works. you can do the sun spot method too.

[Helen Keller]

some years ago several of us tried using welding hoods to view a partial eclipse. even with cutting goggles under the hoods, it was not easy on the eyes. be careful.

Need to sell a buncha libs "Special Eclipse Binoculars"

[Viking350]

When I was a kid, there was a solar eclipse. In school, they said you could damage your eyes using a welders mask. Instead they had us get a cardboard box. In the open side (top of the box) cut half circle holes in the flaps such that the box would go over your head and the flaps close around your neck. With the box oriented normally with the open end up, cut a round hole in the bottom corner of the back of the box. If your box is rectangular, the back is one of the short sides. The front is the other short side. Once you cut the hole, cover it with aluminum foil. Use a pin to poke a hole in the aluminum foil. On the inside of the front of the box, tape a piece of white paper. That will be the screen. When you view the eclipse it was easiest to sit in a chair facing away. Put the box over your head and close it if you can stand that. Orient your head so you are pointing the pinhole towards the eclipse and you will see the picture perfectly on the paper screen. The image will be reversed like in a mirror.

[Krupski]

Thanks for all the replies... especially the idea of viewing the eclipse INDIRECTLY.

A few years back (the Venus transit across the sun) I used a spotting scope to project an image of the sun on a piece of white cardboard and then photographed the image.

I got this result:





Not quite as good as a NASA photo:





But not too shabby for this setup:

[l921428x]

So what the hell are you asking krup? You know how to do it but you are asking how to do it?
......You just messing with people?

[alismith]

A few years back (the Venus transit across the sun) I used a spotting scope to project an image of the sun on a piece of white cardboard and then photographed the image.

I got this result:






But not too shabby for this setup:

Roger, it appears that your spotting scope set up if far superior to anything mentioned here. Why not just use that set up again? It's perfect.

[Altarboy]

I also watched Venus through welders lens. It was cool.

[Krupski]

So what the hell are you asking krup? You know how to do it but you are asking how to do it?
......You just messing with people?

Not at all. I want to use a welding filter glass and needed to know what number was good enough.

I've now got a decent telescope and camera adapter so I was going to try to use the filter to both look at the eclipse directly and also use it for the telescope / camera.

I'm hoping to get better quality photos than the pinhole or shadow method.....

[JTHunter]

There is a man that was at the eclipse expo in St. Louis back on 6/17 who was selling special sheets of flexible plastic that is the same thing they make those cardboard "glasses". He was selling a 9 x 12 sheet for ~$20. You can cut it with scissors to make a camera filter of your own.
The company's website is: www.scopedawgoptics.com and the phone is 618-401-3342. He is located in Highland, IL.