Solar photography

[Geoff45]

If I use a white light full aperture filter and then put in an Ha filter in front of the camera, will prominences show up? I realise with the Ha and white light filter, things will be extremely faint, but will anything show up with a long enough exposure?
Geoff

[frolinmod]

You'd need a sub-angstrom Ha filter. Your typical CCD imaging narrow band Ha filter is 30 to 50 angstroms (3nm to 5nm) wide. That is far too wide to see prominences.

For white light solar viewing I'm currently using a Lunt Herschel wedge with a Baader solar continuum filter and a Lunt zoom eyepiece. The Baader solar continuum filter is a 10nm wide filter centered around 540nm in the green. I can put the Herschel wedge on the back of any refractor, preferably an an APO or semi-APO. I currently have it on a Stellarvue 80ED with a moonlite focuser. Note sure what it would look like to replace the solar continuum filter with an Ha filter. Probably not much. I don't have a 1.25-inch or 2-inch mounted Ha filter to try. But I suspect it would just act like a very deep red filter.

[Poita]

Pretty sure the white light filter will block all of the Ha anyway.

[Geoff45]

Seems reasonable. I didn't really believe it could be that simple.
Geoff

[Poita]

That's because it isn't :D
You will also need an ERF or you will cook the scope, and the sub angstrom filter + ERF could cost more than your scope :(

I can lend you an ERF, maybe you could buy the 0.5 angstrom filter and we could share ;)

[frolinmod]

Here's a link to what appears to be a picture taken with just such a setup as Geoff inquired about:

http://www.cloudynights.com/ubbthreads/attachments/4899060-sunspot%20group%2030nm%20ha%2012-16%2005Nov11%20small.jpg

Doesn't look any different than a white light picture really.

[5ash]

Just remembered an article in scientific american in the 60's or 70's showing how to construct a spectroscope to observe prominances. Maybe that would be an alternative if your handy , though older technology.
Philip

http://www.google.com.au/url?sa=t&rct=j&q=scientific%20american%20article%2 0on%20a%20prominance%20spectroscope&source=web&cd=1&ved=0CDIQFjAA&url=http%3A%2F%2Fwww.spectroheliosc ope.org%2Fnet%2FProm.pdf&ei=rI24TtPFHOOJiAK557HWBA&usg=AFQjCNF2-7dHE0rFw43Ki9PYdD9oicOnRA

[frolinmod]

Many years ago while at RTMC I had the pleasure to look through a homemade spectrohelioscope. It could be tuned to any line in the solar spectrum you wanted to observe. Now that was interesting!