Solar filter

[AdrianF]

While I was in Sydney I purchased an A4 sheet of Baader AstroSolar Film. I was thinking about making a filter for either the WO66mm or the Orion 80mm scopes, not sure which one yet.
:help:What I would like to know is with either scope is it necessary to make the filter area as large as the aperature or would I be able to use a smaller diameter solar film than the aperature of either scope, obviously I need to make sure that no light from the sun enters the scope except through the filter.
I dont want to waste the Film making something bigger than necessary.
Anyone use either of these scopes to view the sun? What are your thoughts?

Adrian

[gbeal]

I reckon for either of the two scopes you mention, that a full aperture is what you need. Some huge like a C14 perhaps I would do an off aperture though.
Gary

[[1ponders]]

Adrian out of an A4 sheet of film I made a full aperture filters for my ED80, 10*50 binos, 50mm finderscope, 30mm finderscope and still had bits left over that I could have used.

[[1ponders]]

If you've not already seen it, check out the how to article

http://www.iceinspace.com.au/63-136-0-0-1-0.html

[AdrianF]

I had seen the article thanks.
I think I might go to the hardware store and see if I can get some PVC pipe ends the right size before I start.


Adrian

[Rickster]

Hi,
Due to the brilliance of the Sun, you do not need to use the full aperture of the telescope. Obviously if it is a telescope of small aperture, then it really wouldnt be an issue to make it around full aperture size.

Cheers

[[1ponders]]

I agree Rickster if it were only available light levels, but the other issue to consider is resolution, the smaller the apature the lower the resolution. By using a 2" mask on a 4" scope you are effectively stopping the scope down and cutting the resolution considerably and the ability to magnify in half; max usable mag 2" scope 100X, 4" scope 200X.

This may not be an issue for full disk viewing but could cause constraints when trying to view sunspots in detail.

[AdrianF]

Thanks for the info I will use the 80mm scope to view the sun as I have just sold the WO 66mm. Hmmmm more money to buy bigger scope............
I was thinking that I might go and buy some plumbing supplies and make a more robust filter than making on out of cardboard and paper.
I will use full aperature.

Adrian

[mswhin63]

Why does the Solar film always look crinkly, does it affect the view?

Also does it show more detail on the sun or is it better to use glass specialty filters?

[[1ponders]]

You actually don't want it tight Malcolm, so crinkly doesn't affect it at all.

I had a glass filter for my 8" meade and I have film for the ED80. I hardly ever used the glass over preference to the film so I ended up selling it. Not that there is anything wrong with the glass, it was just easier to setup the ED80 than the meade.

[vindictive666]

it tightens up whilst viewing for a while :) so not to tight

regards john

[AdrianF]

I went out this morning and bought the plumbing supplies I need to construct my solar filter half way through building it and......
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It starts to rain.

Adrian

[[1ponders]]

How lucky are you Adrian. Would you please send some filter film here!

[mswhin63]

Thanks for the advise, what bout close up image details, do you need special film or special scopes or can it be done using the film?

or does it just give white ball with black sunspots!

[Merlin66]

The Baader film is a white light filter.
It will "just give white ball with black sunspots"
A green or continuum filter will improve the contrast.
To see close-up views of the Hydrogen surface and prominences you need a specialised Ha filter ie the Coronado PST or Solar Max filters.
These are expensive, starting around $750 plus second hand!

[mswhin63]

Cheers, think I will wait till there is more sunspot activity or possibly more money. Still need get some decent lenses.

[AdrianF]

Well I managed to finish the filter and I am amazed that something so flimsy (the film) can be so effective. There was a break in the clouds for about 5mins and gave it first light handheld with a 25mm plossl eyepiece. Shows potential be much better on a mount of some kind.
I managed to get a clear aperature of 80mm. I will post some pictures of the steps I took to make the filter tomorrow.
Total cost of filter $10 including the piece of film.

Adrian

[vindictive666]

most likely know this, cover lenses with filter or get a very quick trip to hospital :(


regards john

[circumpolar]

Where in Sydney did you purchase the solar film from?

[AdrianF]

I bought the film from Andrewscom. $50 for an A4 sheet.

Adrian