Is there any material I can use for an aperture solar filter?

In summary, the conversation discusses various options for safely viewing the sun without a solar aperture filter. Some suggestions include using DVDs or welder's glass over the telescope objective, or purchasing a commercial solar filter. It is emphasized that using an eyepiece filter for solar viewing is not safe. The conversation also includes images and recommendations for solar telescopes and further resources.
  • #1
nuffsed
2
1
I live in a small town and would like to make some observations today. However i don't have a solar aperture filter, i only have an eyepiece filter of which i do not trust. So is there any household items, materials i could use safely to save me from from ordering on the net and waiting however for the film to arrive. Someone said DVDs split in in half (1/2 depth/thickness) works but is that good advise or just bad advise?

I should say that the telescope is a D= 76mm( but can be reduced). SO any ideas would be great or am i just hoping for something that does not exist.

Thank you.

P.S
I have no idea what this prefix i need to select is about, i am not at school I am just an enthusiastic beginner of astronomy.
 
Astronomy news on Phys.org
  • #2
I bought a piece of welder's glass from my local "Princess Auto" (a hardware warehouse).

I covered the scope objective with cardboard, cutting a small hole in it, and then taped the welder's glass over that.
 
  • Like
Likes davenn and nuffsed
  • #3
DaveC426913 said:
I bought a piece of welder's glass from my local "Princess Auto" (a hardware warehouse).

I covered the scope objective with cardboard, cutting a small hole in it, and then taped the welder's glass over that.
NICE ONE! Such a simple idea. It seems quite obvious now you say it. Thank you.
 
  • #4
nuffsed said:
i only have an eyepiece filter of which i do not trust.

NEVER EVER use an eyepiece filter for solar filtering

nuffsed said:
Someone said DVDs split in in half (1/2 depth/thickness) works but is that good advise or just bad advise?

not good advice

nuffsed said:
I should say that the telescope is a D= 76mm( but can be reduced). SO any ideas would be great or am i just hoping for something that does not exist.

76mm is a good aperture size :smile:
Easiest thing to use is 3 to 4 layers of a mylar survival blanket over the front of the scope
Start with 4 layers, if it is too faint, reduce to 3 layers.
I used film filters for 40+ years for viewing sunspots and solar eclipses

when you get a bit more money (~US$50 - $170) you can get a commercial solar filter
here's the same thing over the front of one of my telephoto lenses …..

2015_03_14_3302sm.jpg


one of several suppliers
http://thousandoaksoptical.com/shop/solar-filters/full-aperture-solarlite/when you get lots of money, you can get a proper solar telescope like this one of mine ……

IMG_1093sm.jpg


Now the mylar and the commercial filter glass ways are great for showing sunspots on the surface of the sun
And a warning, because we are at solar minimum, there are very few spots to be seen. The sun is pretty lank most of the time.

That solar scope of mine shows prominences on the limb and other features on the face of the sun.
It is a very narrow Hydrogen Alpha (Ha) 0.7 Angstrom and less.

with that you get images like this …….

180909 Ha Cap_14.jpg


180930 Cap 003.jpg


180930 Cap 053.jpg

See my solar imaging thread on PF, here ……

https://www.physicsforums.com/threads/solar-imaging-and-techniques.925656/cheers
Dave
 

Attachments

  • 2015_03_14_3302sm.jpg
    2015_03_14_3302sm.jpg
    40.3 KB · Views: 380
  • IMG_1093sm.jpg
    IMG_1093sm.jpg
    29 KB · Views: 375
  • 180909 Ha Cap_14.jpg
    180909 Ha Cap_14.jpg
    8.1 KB · Views: 354
  • 180930 Cap 003.jpg
    180930 Cap 003.jpg
    12.4 KB · Views: 385
  • 180930 Cap 053.jpg
    180930 Cap 053.jpg
    50.7 KB · Views: 391
Last edited:
  • Like
Likes berkeman, russ_watters and Drakkith
  • #5
Note that the quote below is for DIRECT viewing, not thru a telescope. If you use full aperture of your 76mm telescope, add 4 to the shade numbers in the article.
Quoted from: https://eclipse2017.nasa.gov/safety

Viewing with Protection -- Experts suggests that one widely available filter for safe solar viewing is welders glass of sufficiently high number. The only ones that are safe for direct viewing of the Sun with your eyes are those of Shade 12 or higher. These are much darker than the filters used for most kinds of welding. If you have an old welder's helmet around the house and are thinking of using it to view the Sun, make sure you know the filter's shade number. If it's less than 12 (and it probably is), don't even think about using it to look at the Sun. Many people find the Sun too bright even in a Shade 12 filter, and some find the Sun too dim in a Shade 14 filter — but Shade 13 filters are uncommon and can be hard to find.

For those interested, the 'add 4 to the shade numbers' was calculated from:
(I'm using 1mm pupil diameter here for a safety factor >2. Online search says minimum diameter is 1.5mm.)
Assume eye pupil diameter of 1mm. Area of 0.785sq.mm.
Telescope aperture 76mm. Area of 4 534sq.mm.
Area ratio: 5776 (That's the additional factor of intensity reduction required.)

Welding filter are rated as Shade Number = log10(attenuation ratio)
log(5776) = 3.76
So add 4 to the shade number and you get 1/10,000 of the light thru.
If you can't find any dark enough you can stack them. The shade numbers add.

Cheers,
Tom
 

1. How do I make an aperture solar filter?

To make an aperture solar filter, you will need a material that can safely block out most of the sun's light, such as special solar filter film or aluminized polyester filters. You will also need a frame or holder that can fit securely over your telescope or camera lens. Follow the instructions provided with your chosen material to construct the filter.

2. What materials are safe to use for an aperture solar filter?

The only materials that are considered safe for an aperture solar filter are those that are specifically designed for solar viewing. This includes solar filter film, aluminized polyester filters, and certain types of glass (such as Baader AstroSolar Safety Film). Never use regular sunglasses, smoked glass, or other materials that are not specifically made for solar viewing.

3. Can I use a DIY method to create an aperture solar filter?

It is not recommended to use a DIY method to create an aperture solar filter. The safety of your eyes and equipment is of utmost importance when viewing the sun. Reputable companies have extensively tested their materials for solar viewing and provide proper instructions for constructing a safe filter. It is best to purchase a pre-made solar filter or solar filter film for your specific telescope or camera lens.

4. How often do I need to replace my aperture solar filter?

The longevity of an aperture solar filter will depend on the material used and how well it is cared for. Some solar filter films can last for several years if stored properly and not exposed to extreme temperatures or physical damage. However, it is recommended to regularly inspect your filter for any signs of wear or damage and replace it if necessary.

5. Is it safe to view the sun through an aperture solar filter?

If used properly and with a reputable solar filter material, it is generally safe to view the sun through an aperture solar filter. However, it is important to never look directly at the sun without proper protection, as even a small amount of sunlight can cause serious eye damage. Always follow the manufacturer's instructions for use and never leave your equipment unattended while viewing the sun.

Similar threads

Replies
4
Views
2K
  • Astronomy and Astrophysics
Replies
12
Views
5K
  • DIY Projects
Replies
6
Views
2K
  • Astronomy and Astrophysics
Replies
1
Views
1K
  • Astronomy and Astrophysics
Replies
1
Views
4K
Replies
4
Views
6K
Replies
25
Views
7K
Replies
7
Views
1K
  • STEM Academic Advising
Replies
2
Views
1K
  • Classical Physics
Replies
2
Views
885
Back
Top