I got a solar filter!

[cubinator]

I'd like to find a good solar filter that is not too expensive (<$150), which can be used to view not only transits, but also see features like sunspots and maybe granulation. So far I've found these:

$173.51

$145.00

$129

$89.95 (this one seems perfect but is apparently discontinued. )

$89.00 (this one also seems perfect but the big "Pending Delivery" makes me think it would be a while...)

Any advice?

P.S. I'd like to have it before the May 9 transit, if it's possible.

I've now bought a sheet of solar film, and am waiting for it to arrive in the mail.

The film arrived this morning, and I've assembled a cover with it.

The filter I made with the film works well for viewing sunspots, and cost me less than $50! Yay cardboard!

Edited April 16, 2016 by cubinator

[Guest]

This is kinda off-topic, but... 

Am I the only one who noticed that the "O" in the Adorama image (first link) looks like the Aperture Science logo?

[cantab]

Baader solar film, and make your own holder for it. Cheap and gives high quality images, but be really sure your filter can't fall off your scope!

An A4 sheet will suffice for most, considering that with a large scope there's a case for using a smaller filter.

[cubinator]

1 hour ago, Aperture Science said:

This is kinda off-topic, but... 

Am I the only one who noticed that the "O" in the Adorama image (first link) looks like the Aperture Science logo?

No, you are not the only one.

1 hour ago, cantab said:

Baader solar film, and make your own holder for it. Cheap and gives high quality images, but be really sure your filter can't fall off your scope!

An A4 sheet will suffice for most, considering that with a large scope there's a case for using a smaller filter.

I'm a little hesitant to make one myself, seeing as I have no prior experience with solar filters for telescopes.

Edit: I looked into the process for self-assembly and it seems doable with sufficient cardboard, knife, and tape. I'll consider buying some. How big should I make the aperture for my 8" reflector?

Edit 2: I just bought a sheet of A4 film, it should fit nicely on my 8". It'll probably arrive next week, and then I'll see about making the mount for it!

Edited April 14, 2016 by cubinator

[cantab]

So you know the arms of the "spider" that hold the secondary mirror? Make an off-centre circular aperture that fits between those arms, that's usually a good approach.

[cubinator]

3 hours ago, cantab said:

So you know the arms of the "spider" that hold the secondary mirror? Make an off-centre circular aperture that fits between those arms, that's usually a good approach.

My telescope is catadioptric, so it doesn't have a spider. Since I'm getting a film and making the filter myself, what I'll do is put the film in a (almost) full aperture cap, and if I want less aperture I can attach a cover that will block more light.

[cantab]

Ah, yes, an A4 sheet would be enough for full aperture on an 8 inch scope. I forgot the Imperial dimensions of A4 paper, d'oh.

[cubinator]

1 hour ago, cantab said:

Ah, yes, an A4 sheet would be enough for full aperture on an 8 inch scope. I forgot the Imperial dimensions of A4 paper, d'oh.

The US-shipping website I bought it from said it was 7.9 in wide, so I have to make sure the mount covers the edges. Should be easy enough. Can't wait for it to arrive! *commence the constant refreshing of the USPS package tracker*

[cubinator]

Ok, the film arrived today in the mail. I measured the circumference of the aperture cover of my telescope, to see if I could find a strip of some bendy material that I could make a cylinder out of. I went to the hardware store with a strip of paper of equivalent length to the circumference of the cover, and I also brought the cover itself. In the end, I went with a plastic flower pot, which had an inset which turned out to fit the telescope perfectly! The rest of the pot got cut off, and, once sanded, the cardboard holder would be easy to attach. I made the cover the way the instructions said to, and, with some toil and a lot less than $100, finished the holder. I checked it against the sky and didn't see any holes, so it seems to be fine. I then glued the cardboard holder to the plastic ring. Then it was just wait for the glue to dry and it's now done! I'd test it out now but...

 

 

...it's cloudy. 

[cubinator]

The clouds have cleared some, so I went outside with the filter and held it up to the sun. I could see a sunspot just with the filter in front of me! I went inside and got the telescope out, making sure the finder was covered and that the filter was well attached with some packing tape. The filter works well, although I will probably want to try a smaller aperture cover to minimize flapping of the film, which affects the image. I could see the shape of the sunspot and there was a gray region on the outer edge of it. I'm sure it will work beautifully for the transit!