Solar Continuum Versus 7nm H-a filter

[Luke]

When I took these shots on 29th December, the conditions did not seem up to using a Barlow on the Sun... So I thought it was a good excuse to try a little, not terribly scientific, shootout between the Baader Solar Contiuum and Baader 7nm H-a filter with the Herschel wedge. I have had some success using the H-a filter on the moon (!). These are the results directly after stacking - no sharpening or processing done.

I had been expecting the H-a to pip it, but looking at the results, I think I'll stick with the Solar Continuum for now. That said, if I didn't have a Solar Continuum filter, I'd be encouraged by the H-a result.

I did rotate the H-a image slightly to get it better lined up with the Solar Continuum, but I think the contrast and general detail has not really suffered.

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Dec 29, 2013
Equinox 120mm / Grasshopper 3 (ICX687) / Baader Herschel Wedge

[Pete Presland]

the Solar Continuum has it, defitely a sharper image!

[David Smith]

Interesting experiment.

[Montana]

Much more contrast with the SC that's the winner but then I guess that was what it was designed for

Alexandra

[RikM]

Clear win for the BSC. Nice to see the comparison though

[riklaunim]

You would have to shoot many avis for given filter and then pick best avi for every filter - as seeing easily can spoil the comparison. Those images above doesn't say clearly which filter is better (rapid seeing) - and if you Google you can find super sharp Baader Continuum as well as H-alpha images made with Astrosolar.

Also it's important to note if given filter is IR blocked deep into IR (like Solar Continuum isn't that much and stacking it with a good IR/UV cut filter may increase contrast by cutting the bad far IR).

[Luke]

Thanks for the comments, all

Alexandra, I was wondering whether the SC might win for visual / imaging combined, but the H-a might pip it for imaging? I think I read Alan Friedman has used one for white light, though I don't know under what circumstances, etc.

Piotr, thanks for your insight. This was just a little test, and not very scientific, as I mentioned in my post. My test is enough for me to suggest I don't need to switch to the H-a filter for now.

I took four movies with each filter and result is similar in all four, with no obvious gain I could see on the screen when switching to the H-a. I don't use a UV/IR cut on my ED120 as it does not seem to me to particularly need it (I read somewhere that its Schott glass element may block IR, but I don't know - much seems to be guesswork/trying for yourself/doing what works for you!). For me views with ED120 at the eyepiece are very similar to the view on the laptop screen, which to me suggests the IR is not a problem. But I may be wrong.

I do have to use a UV/IR cut with my ED80. It caught me out at first! The view was very nice at the eyepiece, yet on the laptop screen, it was a fuzzy image. The UV/IR cut sorted ou the fuzz and then the laptop view was similar to at the eyepiece