Hi all.

After geting strong advice from s.a.a not to risk the telscope and
eyepice on solar projection, I would like to check out solar filters
to be mounted in front of the telescope objective.

[snip]

All of this put the following questions to mind:

- What types of details can one expect to see with Hydrogen Alpha
filters that don't appear with the "ordinary" filters? I have the
impression protuberances and surface granularity would be visible.
What about flares? Other details? Would one see dynamic features
i.e. instant movement on the surface as opposed to sunspot positions
that change over hours and days?

The telescope in question is of 80 mm aperture with a 20-60x eyepiece.

- How much more expensive are the Hydrogen Alpha filters than ordinary
ones? 2 times? 10 times?

Any opinions much appreciated.

Rune

I agree with everything you've been told so far regarding the wonders
visible with an H-alpha filter such as the Coronado...it's all true.
However, there are a few things you have not been told, which are not
terrible, but will give you a more accurate picture of using the H-alpha...

I own a 60mm Coronado, which I purchased this year. The first time I used
it, I nearly jumped out of my skin. After the novelty wore off, I began to
see some of the downsides of this expensive toy. I use my H-alpha with a TV
Pronto scope having a focal length of under 500mm. (Unless you change part
of the filter, you are limited to using the H-alpha with a scope no greater
than 1,000mm. If you prefer to use the filter with a longer focal length,
it would cost $1,500 (about) to buy that part of the filter which would
allow you to do so.) With a 10mm eyepiece, the disc of the sun is
completely in the field of view, so all activity on the sun is minute in
size, as compared to the disc of the sun. In other words, the activity that
you want to see appears as _very_ small. BTW, using a barlow between the
telescope and the eyepiece does not help the quality of the image and for
this reason I keep away from the barlow. On the other hand, a CCD or even a
good digital camera allows you to see _much_ more...unfortunately, not in
real time.

The other thing you should understand is that the level of solar activity is
not constant. There are days when you can view for hours and see almost
nothing...because nothing big is happening. During the period of time that
I've owned the H-alpha (about 5 months), I had only one day of viewing that
I would consider spectacular. Keep in mind that I live in the Northeast,
where we've had an absolutely disasterous spring and early summer. Believe
it or not, during the past 5 months, clouds covered the Northeast at least
85% of the time. During the past 3 weeks or more, doing any solar viewing
while temperatures hovered in the area of 100 degrees was out of the
question.

So, before you part with the bucks to buy one of this filters, keep the
above in mind. Keep in mind also that I am no authority on H-alpha filters.
What I say here are only my early feelings. It's quite possible that with
more experience I may change my mind completely. Finally, in spite of what
I said above, the H-alpha, while not perfect in my mind, is still quite
fantastic!

Al