View Full Version here: : Can you use an H-alpha filter behind a Baader solar film filter?

07-07-2010, 05:13 PM
I think the topic asks it all.

I have a standard solar film filter - the 99.9999% sort of thing - so I just get white light images.

Now you have reduced the light intensity to something the CCD can cope with, can you then use a H-alpha filter to get narrow band?

07-07-2010, 05:20 PM
You can use any standard filter when using Baader solar film - like the Baader solar continuum or K-line filters. You can also try H-alpha but it won't give you image like a true H-alpha solar scopes. H-alpha for night imaging are to broad for that :D

Paul Haese
07-07-2010, 05:20 PM

You need a Ha solar filter set to get Ha images of the sun.

08-07-2010, 07:40 AM
There's no benefit in using a conventional Ha filter with a Baader solar filter.
You can use a Green or Continuum filter to improve constrast in white light observing.

08-07-2010, 10:24 AM
Thanks for posting that question Andrew, cause I had the same thought!
I have a Ha filter but no solar filter yet. And some of the pics I see of the sun in Ha, I thought were done by using a solar filter and Ha.
So for pics of the Sun in Ha one must use a special scope?
Just re-read Paul's post....Ha solar filter set? Where from?


08-07-2010, 11:39 AM
For Ha observing of the Sun, you need an extremely stable, narrowband filter centred on Ha. A "normal" DSO Ha filter may have a bandwidth of say 10nm; the solar filter needs to be down BELOW 0.1nm.
To do this, a Fabry-Perot interference filter (etalon) is usually used in conjunction with a blocking filter.
The F-P etalon produces a series of bands about 0.1nm wide and about 0.8nm apart, these cover the whole spectrum. The particular band we want at Ha is "filtered" out by using a very narrowband Ha filter ( about 0.6nm) called the Blocking Filter ( ie it blocks out everything other than the required wavelength). So the combination of the etalon and the BF give us the resolution at Ha.
Solar filters and scopes are produced by Coronado (PST and Solarmax), Lunt, Daystar and Solarview. They start from around $800 for the introductory 40mm PST/ 60mm Lunt and quickly rise to the $$$$$$ for apertures up to and beyond 90mm.
Hope this helps.

08-07-2010, 11:58 AM

Wow! did not think it was so complicated!:scared3:
I kinda understand blocking out filters....but all the other stuff????
Need to do some Googleing!
Thanks for the extra homework!

08-07-2010, 12:04 PM
gets expensive!
The F-P elements have to be much better than 1/15 to 1/20 wave flatness and held together, while "tuning", to be parallel within sub micron tolerances. Certainly not your average filter!!!!

08-07-2010, 12:27 PM
more intense solarcontinuumwaveflatnesstuningwit hparallesub microntolerancesaveragefilter stuff......+ the f-p element stuff
I'll get there eventually:lol: