Do you use any filter for HA imaging?

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 12:04 pm

Hi everyone,

I'm just curious. Do you use any filter for your HA video recording?

Personally I've been using a UHC/LPR Filter by Celestron but since a few days I'm using the Baader Neodymium (Skyglow).
I find that both increase the contrast. The new Baader Neodymium works even better than the Celestron and it's also an IR-Cut.

In TS selling pages here is written:

The filter opens in the red around 656.3 nm. This characteristic is important for many objects in the solar system (e.g. Jupiter's great red spot) but also for many deep-sky objects emitting red light.

So I decided to give it a try. And in my opinion if works very well.

Does anyone have any experience in HA imaging with it?

Does anyone use any particular filter to increase contrast?

Thanks,
Andrea

edobosz · Post by **edobosz** » Thu Mar 01, 2012 12:19 pm

No I have not tried any filters. However I have often thought of trying some out. Next time I have some time and the seeing is ordinary, I might try several filters and compare outputs.
Ted

Post by **Montana** » Thu Mar 01, 2012 12:28 pm

Hi Andrea,
I use a hydrogen alpha filter which is only 0.07nm wide, I think the only way to make that narrower for an even tighter width (more contrast) is a second hydrogen alpha filter

certainly no IR leak there or I wouldn't see any features at all

Regards
Alexandra

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 1:28 pm

I ordered yesterday a couple of HA filter that are made to be stacked/tilted together to have a subarmstrong bandpass. Probably with them I'll have some good improvement also in contrast.

Post by **Merlin66** » Thu Mar 01, 2012 2:17 pm

Are we talking about Solar Ha imaging i.e. with an etalon filter? If so, then the only way of improving things is the double stack.
If we're talking white light and additional contrast filters, the best performers seem to be the green filters - continuum or OIII.
Andrea, I'd be very interested to hear more about these "stacked" Ha filters - The only ones I know of which may come close are the 2A filter sets out of Germany.

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 2:42 pm

Yes HA with Etalon.

I know it may sound strange but the contrast improvement is evident. I'll try to shot with and without the Skyglow Neodymium filter to show you the difference. It's not double stacking

But it costs 1/10 than DS.

Yesteday I ordered those two:
http://www.ebay.it/itm/150711495932?ssP ... _669wt_936

If they work as promised they should have a very good performance if properly tuned.

I already started building a "tilter". Are you aware of any commercially available filter tilter?

Andrea

Post by **Merlin66** » Thu Mar 01, 2012 2:49 pm

Hmmm
Certainly sounds interesting - a 25mm combined Ha/ blocking filter for $200 odd ....
Telescope Service have a couple of filter tilters but I don't think they would be accurate enough for this job....

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 3:28 pm

Yes my intention is to use it also as a sort of "large" BF. Let's see if it can work.

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 3:28 pm

Thanks a lot Joe. I'll take a look at it

swisswalter · Post by **swisswalter** » Thu Mar 01, 2012 4:17 pm

Hi Joe, Hi Andrea

yes I have beeen supplied with the correct tilting filter unit in the second run. However I have no mounted them yet. I'm on the way to it. I have also ordered a custom made filter tilting system from aok. it sits on my desk and is one of the first things I'll try when I have spare time and the sun shines. I'll let you know when something interesting is showing up.

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 4:20 pm

Can you post some link/picture, please?

Thanks!

swisswalter · Post by **swisswalter** » Thu Mar 01, 2012 5:27 pm

Hi Andrea

here is the link to the supplier

www.aokswiss.ch

Ask for the adapter he made for walter

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 5:33 pm

Ask for the adapter he made for walter

Great thanks, Walter!

Post by **marktownley** » Thu Mar 01, 2012 6:38 pm

Okey dokey... Your first point; The neodymium filter has a IR cut so you may well find this is improving things especially in a homebre Ha system...

Regards the fleabay filters, I have exactly the same ones

This is gonna be a big topic - where do you want to start

Post by **Merlin66** » Thu Mar 01, 2012 6:40 pm

Hmmm
When I put the spectroscope on a Ha scope with a good blocking filter/ etalon I don't pick up anything other than the narrowband 0.8A at Ha........

Post by **Montana** » Thu Mar 01, 2012 6:43 pm

I agree Merlin!

Alexandra

Post by **marktownley** » Thu Mar 01, 2012 6:44 pm

Sometimes a 'dimming' of the image is all that is required to increase perceived contrast.

*thinks passing clouds when viewing Ha at the eyepeice*

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 7:12 pm

I agree but that's why I'm asking you all.
My experience is that by using those two filters, contrast is much better.
And it's not a matter of "dimming" as I don't get that results with a polarized filter but with them I have a "washed" version of the image without them.

Anyway... I'll make a few comparison video tomorrow

Surely the two HA filters will do a muche better job

Post by **marktownley** » Thu Mar 01, 2012 7:16 pm

Surely the two HA filters will do a muche better job

Depends how you use them

What are your plans?

andreahaku · Post by **andreahaku** » Thu Mar 01, 2012 7:41 pm

Stack them together with a tilter I'm building.
I'll also try with the two CaK filters I'm still waiting to arrive!

Post by **marktownley** » Fri Mar 02, 2012 12:16 am

Hi Andrea,

The filters you have bought from EBay HAVE to be used together in a tilt tune arrangement for them to work, in a telecentric beam f30ish or longer. You will find it very difficult to incorporate them into any Ha system you are running already, in a double stack arrangement, if thats where you are thinking of going with this. Elaborate more on your thoughts - we never have problems on SolarChat, just solutions we haven't come up with yet

Mark

Post by **marktownley** » Fri Mar 02, 2012 12:22 am

[quote]with antireflective coating i get much better surface details

This could well be a pertinent thing; since removing my mini-erf from the blocker I have found I have extra reflections I have to deal with. I don't doubt the narrow bandpass that is recorded spectrally from Ha arrangements, but if there are reflections floating around this will have a negative effect contrast wise. Andrea - you mention you tried polarisers, crucially were these circular polarisers and where did you place them in the optical train?

andreahaku · Post by **andreahaku** » Fri Mar 02, 2012 6:46 am

Thanks Mark. I have friend that used them already with success.
So I already elaborated with them some possible solution before buying

I already read about the Groski setup. For now it's not my intention to build something like that.
I'll try and see what I'll be able to do with them... always good to experiment!

Post by **Merlin66** » Fri Mar 02, 2012 6:48 am

Vanter,
I'll find the images of the etalon "comb" and the results with the BF15 and upload later today.
I had to use the Spectra-L200 spectroscope to get the high resolution. The MG80 only has a 300 l/mm grating so its designed for lo res spectra.
The etalon "comb" I'm sure extends all the way across the spectrum from UV-NIR, and has a passband of 0.8A at 10A spacing....

Post by **marktownley** » Fri Mar 02, 2012 7:15 am

Thanks Mark. I have friend that used them already with success.
So I already elaborated with them some possible solution before buying

I already read about the Groski setup. For now it's not my intention to build something like that.
I'll try and see what I'll be able to do with them... always good to experiment!

Okey dokey, keep us updated as to how you get on. Hardest bit I found was to make a decent tilt tune system that didn't involve me cutting my scope up. I got it to work (short term) visually and with very, very limited photographic success but never really got it to show anything more than the brightest of proms and some fuzzy surface detail. The problem seemed to be reflections generated in the laminate layers of the blocking filter that brings down the contrast of the image. I always got much better views with my DS40 and as winter came (and went!) the project went on hold while I used my DS40 for the brief viewing window. I intend to revisit the project again as we move into the new year now the sun is up for longer allowing me to test it. Will let you know how it develops!

Post by **Merlin66** » Fri Mar 02, 2012 7:28 am

The attached image shows a 1sec exposure through the SM60 etalon. The "comb" extends across the whole spectrum, but should be blocked around 600nm by the ERF. The trace extends from about 580nm to 700nm. The bandpass is 0.8A and spacing 10A.
You can see where the solar Ha line sits on the etalon (the dip)

The other image is the blocking filter (BF10) with the mini erf. This needed a 20s exposure! You can see the Ha dip in the 5A wide bandwidth...a bit noisy to the sides but no other transmissions.

Post by **marktownley** » Fri Mar 02, 2012 7:33 am

Was the light source a broadband source I take it Ken? sunlight?

Post by **Merlin66** » Fri Mar 02, 2012 7:37 am

mark,
Yes. Just put the filters in front of the spectroscope and pointed to the Sun.
The intensity values are on the same scale ie the etalon gave a reading of 194000 (1sec)whereas the BF only gave about 44000 in 20sec. (both from a base of approx 40000)

Post by **marktownley** » Fri Mar 02, 2012 7:53 am

Was the ERF in place on the etalon?

Post by **Merlin66** » Fri Mar 02, 2012 8:01 am

Mark,
Yes. I haven't the courage to pull the SM60's apart.....

andreahaku · Post by **andreahaku** » Fri Mar 02, 2012 8:31 am

Great. I made a simple tilting mechanism. As soon as I got the filters I'll post pictures of it showing (if and) how it works.

I'm very new to solar imaging (just two months now). I'm reading and testing as much as I can. Surely I have a lot of of knowledge background lacks but I'm trying to build it as fast as I can by studying and experimenting. Usually the best way to learn is try things out and see what happens.

I really appreciate your help and I made a lot of steps forward thanks to your already stated knowledge and educated answers to my sometimes silly questions

Thanks again everyone!

Post by **marktownley** » Fri Mar 02, 2012 2:03 pm

Mark,
Yes. I haven't the courage to pull the SM60's apart.....

This is very interesting! Take a look at the following transmission curve for the SM60 etalon

Cor-SM60-log by Mark Townley, on Flickr

Quite clearly there shouldn't be any output in theory below ~500nm, however looking at your curve there obviouslly is. This must mean that the etalon generates these peaks of transmission at different off band frequencies than goes into it (does that make sense

) Very curious!

Post by **marktownley** » Fri Mar 02, 2012 2:05 pm

[quote]Great. I made a simple tilting mechanism. As soon as I got the filters I'll post pictures of it showing (if and) how it works.

How are you achieving the focal ratio needed for the omegas to work?

Post by **Merlin66** » Fri Mar 02, 2012 2:14 pm

Mark,
No...don't get confused with my spectral trace - it only covers down to about 580nm...
I have tested "bare" etalons which show the whole spectrum. Obviously with the ERF still in place, I'm sure if I went down to the 500nm wavelength it would start blocking...

(I've editted my previous message to remove the ambiguity)

Post by **marktownley** » Fri Mar 02, 2012 2:21 pm

Mark,
No...don't get confused with my spectral trace - it only covers down to about 580nm...
I have tested "bare" etalons which show the whole spectrum. Obviously with the ERF still in place, I'm sure if I went down to the 500nm wavelength it would start blocking...

(I've editted my previous message to remove the ambiguity)

Ahhhh, makes sense! I saw the 350 and 700 on the bottom of your trace and assumed it was scale in nm :silly:

Post by **Merlin66** » Fri Mar 02, 2012 2:29 pm

Mark,
No, those were "raw" data - intensity/ pixel.....

depes · Post by **depes** » Fri Mar 02, 2012 7:23 pm

Salve Andrea

If you had visited my blog,

you would have seen that since December of 2011, I use Neodymium Sky Glow filter...with very good results...

Saluti....

andreahaku · Post by **andreahaku** » Fri Mar 02, 2012 8:03 pm

Ciao,
Very nice pictures. I particularly like the prominences. They are very good!
I use the Skyglow Neodymium and results ad very good as well.
I'll make a comparison with or without it sooner or later

Post by **marktownley** » Sat Mar 03, 2012 4:41 pm

Hi everyone,

I'm just curious. Do you use any filter for your HA video recording?

Personally I've been using a UHC/LPR Filter by Celestron but since a few days I'm using the Baader Neodymium (Skyglow).
I find that both increase the contrast. The new Baader Neodymium works even better than the Celestron and it's also an IR-Cut.

In TS selling pages here is written:

The filter opens in the red around 656.3 nm. This characteristic is important for many objects in the solar system (e.g. Jupiter's great red spot) but also for many deep-sky objects emitting red light.

So I decided to give it a try. And in my opinion if works very well.

Does anyone have any experience in HA imaging with it?

Does anyone use any particular filter to increase contrast?

Thanks,
Andrea

Andrea,

I have tried the Baader Neodymium filter today whilst imaging and you are definitely onto something here, certainly with my system is setup... I'm just processing my full disk and the contrast gain is astonishing to say the least... Can't decide whether smart sharpen or I-USM is looking the best on it, both are good, the difference is subtle...

Thank you!

Mark

andreahaku · Post by **andreahaku** » Sat Mar 03, 2012 5:01 pm

I'm more than happy about that. Probably with some HA filter results may be even better. I refer to filters like the ones used for DS (between 6-10nm). I still have to try with them.

Today I recorded a couple videos, with and without the Neodymium. I'll post the raw stacked images probably tomorrow to show the difference. But I can tell you already that it is huge.

I use one pass of Smart sharpen at 500% and then use high pass technique. The single smart sharpen pass works better than iterative approach. At least for me.

Andrea

Post by **marktownley** » Sat Mar 03, 2012 5:05 pm

I'm more than happy about that. Probably with some HA filter results may be even better. I refer to filters like the ones used for DS (between 6-10nm). I still have to try with them.

Today I recorded a couple videos, with and without the Neodymium. I'll post the raw stacked images probably tomorrow to show the difference. But I can tell you already that it is huge.

I use one pass of Smart sharpen at 500% and then use high pass technique. The single smart sharpen pass works better than iterative approach. At least for me.

Andrea

Same here, I recorded a full disk with and without the Baader Neodymium in place, just about finished the 'with', but out with relatives tonight so susupect the 'without'comparison will have to wait till tomorrow like yourself.

There's something curious going on, because my ERF is a 7nm Baader Ha filter, so in theory the neodymium shouldn't do anything, but it quite clearly does. My theory is that the glass substrate is reducing blooming in the infra red...