How do I build a solar filter?

How do I build a SAFE solar filter to view the sun using my 12.5" f/5 Dob?

Can you point me to any links discussing this?

Thanks,
Glenn

This is true. But a offset aperture mask with Baader film attached to cover the hole makes a nice solar filter. Easy to make and the film can be purchased anywhere.
Floyd

Oh, and there's one more thing that you ought to consider. If your 12.5" f5 Dob is a truss tube scope with a shroud, you may want to forget the whole thing. If stray sunlight gets in around the edges, it's all over.

If you're feeling daring, you could make a lightweight aperture mask (with the trusty Baader film) that's much wider (20" or so) wider than the mirror all the the way around. This would work, but I wouldn't let the general public use this type of arrangement for solar viewing!

And, of course, if you've got a tube dob, ignore everything that I've just said!