Solar Filter

[-George-]

Hello,

I have a GSO 12" scope and wanted to get a Solar Filter for it.

I rang up a few places, they have Solar filters made of Mylar. Then I found what Alex said about the BAADER solar filters. They do not use Mylar.

Then, I read those that want an even surface can not get the Film type filter but a glass type or something rather.

What is the best type to get and the most safe?

The only concern I have is, you buy the filter, its faulty or not made correct and you end up blind for life because of needing to trust a manufacturer did it right and you do not end up with a dud that looks ok but in actual fact is not good.

Also, observing the sun, is this something you can from day to day, or, there will be repercussions?

Obviously we only have 1 set of eyes, once destroyed, that is it, forever. So I hope you can understand why the questions/concern.

Thanks

[barx1963 (Malcolm)]

George
Bintel do the Orion off axis, see http://www.bintel.com.au/Accessories...oductview.aspx which is glass.
The Baader ones I have used, but only on a camera lense, not a scope, but with both these types care must be taken to ensure that the filter is undamaged and it is very securely held to the scope.

Malcolm

[mental4astro (Alexander)]

George,

When we spoke last night, and I started describing the Baader Solar Film, I began by asking if you know of 'Mylar foil'. You said no and I said the solar film resembles aluminum foil. This was to describe what the stuff resembles. I didn't say it was made of Mylar. I never mentioned Mylar after you said you didn't know of it. If i had said it was made of Mylar, i felt i had corrected myself at the very start of our 1hour conversation, i certainly also never more mentioned Mylar. Sorry if this caused confusion with you.

Edit: following on from Malcolm's post, Baader makes two types of films, one for visual use and another for photography - the printing on the product cover is very clear about this so there can be no confusion by the end user.

We covered safety issues too with solar films and scopes, but it is good that you are seeking a second opinion - I will be interested in reading other people's thoughts in cse I have been grossly misinformed myself! Last thing I want to do is compromise my eyesight or anyone else's!!!

I take safety with solar viewing very seriously. I recently purchased a little scope from a fellow IIS member and it came with a Solar Film filter that was shop-made for that scope. First thing I did was examine its integrity by putting it to a bright light - it was riddled with pinholes and the film was no longer uniform in density. Straight into the bin with that thing. I wasn't upset with the seller as I didn't care for the filter and wasn't expecting it. But I did my own inspection of it before even considering using it. Like you George, I only have one very precious set of eyes!

[Merlin66 (Ken)]

George,
I've been actively observing/ imaging solar in both white light and Ha for many years.
I have had and tried MANY different filters.
Bang per buck the Baader solar film is the way to go. Optically much better than the "average" glass filters.
I'm a little surprised to hear comments about pinholes etc. My Baader film filters are now almost eight years old and as good as new. When not in use they are stored in a sealed Tupperware container.

I don't recommend the Herschel wedge for beginners - an expensive option, BUT if you do get bitten by the solar bug they are the only way to go. The white light views they give are as good as they come.

[-George-]

Thanks for the feedback.

Alex, I think I confused you here

I know the BAADER do not use Mylar as you had mentioned (I also read it to). The only reason I had a question about Mylar was because the telescope shop I rang that you mentioned on phone to call as they may have solar filters... was not a BAADER but a solar filter made of Mylar. That is why I brought the question here... whether Mylar is good or bad and what not.

I also noticed you can get a 300mm BAADER film to cover the entire front of the scope giving you the entire 12" of resolving power for the sun rather than the 50mm hole...

Thoughts on that?

[Merlin66 (Ken)]

It would be interesting to know the Brand of the "Mylar" filter... The only other film filter I've seen is the American "Seymour" brand which looks like a piece of black garbage bag....
The sweet spot for white light observing is around 100 - 150mm aperture.
Using a full sized aperture filter above this size doesn't add any detail.
(Unless you are blessed with exceptional seeing conditions!)

[mental4astro (Alexander)]

No problem George.

Ken, that little filter I mentioned was several years old, and though in its own box it was knocking about lose in a larger box with other stuff. I don't think it wad looked after gently enough. Anyway, it won't be tempting anyone to use it now. But these solar films are delicate and require 'cotton gloves' care.

George, you won't gain anything with a full aperture 12" solar filter, particularly with visual, and I doubt with photo either. You are viewing typically no more than at 150X, so going beyond 50mm to 100mm is all that you need. The small aperture opening in the lens shade of your scope is plenty to start with. It is also a ready-made opening to use with the solar film without needing to make a new full aperture mask with an off-axis hole. You can explore this avenue down the track. That is the great thing about the Baader Solar Film - you can make several filters from the one sheet.

Edit: good to read Ken's advice on the white light sweet spot.

[Derek Klepp]

George get the solar film the glass filters are not very good especially if you wish to image down the line.With a 12' aperture an off axis filter will probably give you a better view 99% of the time.Remember there is a visual and an imaging Baader film get the one for your needs.

[sil (Steve)]

The Baader film is the way to go, just don't crinkle/crease it in any way to be safe. Its cheap enough to replace if you are concerned. It comes flat with protective boards. and if you're worried approaching the eyepiece, start with defocusing then find the sun, can be tricky, maybe add a moon filter/neutral density filter to your eyepiece if you have one as the sun will be bright still and might help contrast as you focus.

Still I've never heard of anyone having problem with baader film or even those cheap eclipse glasses but if you're still unsure then don't look at the sun and definitely don't go against the advice of what to do. Do NOT put baader film on your eyepiece (hoping to save money on covering a smaller hole) as the sun will be focused there and just burn through it. the filter needs to be the first thing the suns rays hit so the harmful wavelengths are blocked before the enter the optical train and get focused.

I used an older smaller scope i no longer use with a baader filter for solar viewing the transit of venus while photographing it. I made the scope filter using a piece of plumbing hardware the fitted the end of the scope. For my camera lens I used a step up filter ring that easily screws into the lens. in both cases i built my filter by carefully laying the sheet of baader film out flat, applying an even coating of glue (tarzans grip from memory) to the front edge of the ring i could attach to scope/camera then sitting the ring glue down onto the filter sheet and adding some weight so it sealed evenly and fimly then left it alone for a week for it to cure fully. then i added some glue to the excess and folded it up around the sides of the ring, maybe adding a rubber band or some tape to hold it flat in place, then leave it alone for a week then i ran black electricians tape around the side to make sure it was flat and sealed. This way the front of the filter stays flat and I wasn't "stretching" it over the end of something which risks stretching the filter and weakening its protective capabilities and avoids light leakage from the edge. Works a treat, looks good and i keep them safe in there own tupperware containers for storage. I suggest you first find something you can securely attach to the end of your scope before doing a DIY (eg: a replacement end cap you could cut the middle out of that you can securely attach the film onto). The film doesn't have to be perfectly flat, its wont make a difference, just don't scrunch it up into a ball in your pocket then stretch it over the front of a scope.

Also don't forget to cover your finderscopes so they don't become a hazard.

Yes there are alternative DIY methods for solar observing but the baader film is purpose made for the task to eliminate the harmful spectra parts other methods might only remove the visible light parts and leave other non-visible rays to come through.

I had similar reservations to you when i started solar and i now have a nice HA scope but the white light filters are still useful for quick observations of sunspots and dslr photography. I trust the baader film is doing its job, my stroke last year did more to my eyesight than anything else. Good luck!

[-George-]

Thanks for the feedback everyone.

So where can I buy Baader film for viewing live (not photography)?

I got an adjustable polarized moon filter that came with my 300mm GSO, would you attach that to the eyepiece just to reduce the brightness more?

[Merlin66 (Ken)]

http://www.ozscopes.com.au/baader-as...fety-film.html

There may be other suppliers.

[astrodavid]

Try http://www.myastroshop.com.au


Baader - Astro Solar Safety Film 20 x 30cm - Visual Use

http://www.myastroshop.com.au/produc...sp?id=MAS-018F

Baader - Astro Solar Safety Film ND5 - 100 x 50cm - Visual Use (larger size)

http://www.myastroshop.com.au/produc...p?id=MAS-018F2

Baader - Astro Solar Safety Film ND3.8 100 x 50cm - Photographic Use

http://www.myastroshop.com.au/produc...p?id=MAS-018F3

[sil (Steve)]

Remember the law of buying astro gear means the sun spots will vanish when you have your filter. And intense stormy weather too will show up. The best thing about observing our nearest star is you can be pretty sure you're looking at the right object in the eyepiece. If you have a goto mount they default to NOT pointing or tracking the sun, its something you have to enable. Not sure where I bought my filter sheets from, possibly ozscopes, it was part of a bulk gear purchase I made. The normal reputable sellers should be fine to order it. You might want to check stock availability, the solar eclipse in Europe tomorrow would have created a demand for baader film. Good luck and happy viewing!