Question about solar filters

[trebob]

I just picked up a solar filter for a celestron nexstar 114gt . Maybe I'm just being paranoid, but the thing looks to me like a piece of tin foil stuck on a ring of plastic. I decided to look it up on celestrons website (almost all the way down) and just wanted to get some more opinions before I take the chance of burning my eyeballs out in June.

from celestrons website:
Celestron Solar Filters are made with Baader Astro Solar™ Safety Film. Far superior than any existing glass, Mylar or polymer filters, they lead to brighter, sharper, and higher contrast images. Astro Solar™ Safety Film is clear and homogenous and attains the optical performance of high quality plane-parallel glass filters—it is diffraction limited! Double-sided metal coatings have uniform density and good color balance across the entire field ensuring razor sharp images from edge to edge. Its rating is ND-5 which means that the film transmits 1/100,000 of visible light (.001%) while reflecting (blocking) 99.999%of unwanted light. The film absorbs all ultraviolet rays while coating reflects infrared light rendering both absolutely harmless. For added assurance, Baader Astro Solar™ film has been declared safe for direct solar viewing by the German National Bureau of Standards for eye safety.

Like I said, just wanted to make sure anyone with more experience than I have would approve.

Thanks.

[tngolfplayer]

I haven't used any made from the Solar Film. I use my Orion Solar Filter, which is glass. I don't think it would be unsafe to use, not if Celstron themselves are using it.

If you want a comparison in colors you can look here for a picture I took earlier this year with a glass filter, and you can look here for one that I believe I remember was taken with a film filter.


Of course the best solar photos are taken with these types of filters. The Hydrogen Alpha filter sets give, in my opinion, the best view period. Of course they are a lot more expensive.

[Mainframes]

I've used Baader solar film. I just ordered an A4 sheet and constructed a cardboard cap that fits over the end of my telescope, which works just fine as i've used it a few times now. Took some photos through it a while ago and need to get them developed at some point....

[lek]

If you want a comparison in colors you can look here for a picture I took earlier this year with a glass filter, and you can look here for one that I believe I remember was taken with a film filter.

Been using the baader filter a bit myself, sun showed yellow early morning and white during the day so its colour distortion isnt quite that bad...

Some of my photos turned out blue, but i think it was mainly because of incorrect exposure and photo lab messing up...

Oh and im not blind yet

- lek

[Wally]

baader filters are quite common and safe to use. Have no fear.

that said, the one I bought for my LX90 was actually marketed by celestron as well, and didn't fit quite snug enough on the Meade to satisfy me. Had me worried a gust of wind might blow it off the scope while I was viewing (ouch!). I just stuck small strips of the fuzzy part of velcro around the rim to add more friction, and no more worries. Wally

[aurora]

Sky ant Telescope has some nice articles from a few years ago, a review of the Baader material, and a comparison review of a half dozen different solar filters. You can find the articles on their web site, but unfortunately, they now charge to see them.

So I'm not linking to them.

Here's a dealer that has some info:
http://www.kendrick-ai.com/astro/solarfilters.html
and mentions a yahoogroup on solar viewing.

What you should do with any solar filter is check to make sure it mounts securely to the telescope (as was already suggested by someone else) and also I always hold it up to the sun and make sure that there aren't any pinholes in it.

I googled and found this review:
http://www.cloudynights.com/accessories/Baader.htm
and also a mention of a review on s.a.a, so you might want to google the sci.astro.amateur newsgroup.

[Jason Thompson]

That sounds much like my solar filter. It should be safe to use, but always make sure it has no pinholes in it (look at the sun through it without the telescope) and that it fits snugly and tightly over the end of your telescope so that there is no fear of it being blown off by a gust of wind or falling off if you happen to knock the tripod while viewing.

Oh, and don't forget to take the finderscope off your telescope, or cap it, before looking at the sun. Some have been known to melt, apparently.

Another good hint is that if your telescope has a diagonal mirror, use this to orient the eyepiece so that you are effectively looking at 90 degrees to the sun. That way if you happen to glance up from your viewing you don't glance into the sun (not a problem on a Newtonian reflector).

[Charlie in Dayton]

I've made Baader filters for binoculars and monoculars, and the imaging is fantabulous...I used the basic recipe for homemade cells from the Baader page.

I've also made a Baader filter for a 105mm reflector, and Thousand Oaks black film filters for the 105mm and a 76mm reflector. It's been cloudy and raining (ratz...) so far, so I haven't been able to test them yet...but I look forward to viewing Sol this way.

As long as due caution is exercised, and the instructions are carefully followed, homebrewing solar viewing filters is safe.

[Charlie in Dayton]

I've finished the Thousand Oaks black mylar filters, and had just a short time to experiment with them, but already I'm extremely impressed. The view is more natural (a more muted yellow tone, not glaringly blue white like the Baader), and from some of the club members I've talked to, the TObm is much more amenable to handling.

Let me get a few more pictures developed (yes, some of us use film) and get some words down...I do believe a comparo will be the May submission for A New Series Of Articles.