Solar & Narrowband Filters

[Ric]

Hi all,

I intend to purchase a full apeture white light solar filter for the upcoming transit of Venus as well as solar photography.

I've been reading threads on the pros and cons of white light filters and Ha scopes and understand that the white light filter lets through natural light therefore you are only able to view sunspots, while the dedicated Ha scopes allow you to view prominences.

My CCD camera is a Meade DSI II Pro with 12nm Astronomik NB filters and I was thinking that if a white light filter is essentially letting through natural light albeit 99.99% reduced then could I use a 12nm Ha filter to view and image solar prominences

Does this seem like a viable solution by combining the two or are the solar Ha scopes and their filters in a completely different basket.

I am interested to hear your thoughts on this idea.

Cheers

[casstony]

While various line filters, narrowband filters and color filters can increase contrast when used behind a white light solar filter, none of them are narrow enough (afaik) to show proms or other Ha features.

Ha scopes work at less than 1 angstrom; 12nm = 120 angstroms.

Edit: google tells me that up to 10nm can be useful for proms, though with reduced contrast, so it might be a matter for experimentation.

[Ric]

Thanks Tony

That is interesting to know, I'll have to experiment a bit when it arrives.

It will be interesting to see the results.

Cheers

[OICURMT]

I had a lot of the same questions. Finally sought some advice from members on this forum (great resource btw, thanks to those who offered sound advice, Merlin in particular).

Took me a while to figure out what I "really" wanted. Something for both visual and digital, something flexible and portable. Decided against a dedicated scope, as one more scope around the house will just get me into more trouble with the better-half. So, a white-light filter for the SCT and etalons for the ED80. Allows the solar components to easily fit into a small pelican case.

As for the Ha-filters (etalons)... The following threads may help.

http://www.iceinspace.com.au/forum/s...ad.php?t=84303
http://www.iceinspace.com.au/forum/s...ad.php?t=84215
http://www.iceinspace.com.au/forum/s...ad.php?t=72540

OIC!

[Merlin66 (Ken)]

Ric,
The DSO type narrowband filters 10nm etc don't work for Solar.....
The bandwidth is far too great..
To observe the solar proms etc in Ha you need a bandwidth around 1-2 A (0.1 -0.2nm)
A continuum filter or a green filter can improve the contract when used in conjunction with a white light filter....

[Ric]

Thanks for the info and links lads.

I'll have to do a bit more research but there's plenty of time before the transit.

Cheers