H-Beta filters

[KenG]

What's the best Horsehead filter, 9 Angstrom or 12, or do they both give similar results?

[Guest]

I assume you are talking about the bandwidth of the filter? I have always used the 9 nm myself (I think the filter width may well be 90A rather than 9A for visual use anyway). Dark and transparent skies are almost as much of a requirment as the filter

Owen

[KenG]

Yep! I'm talking bout the bandwidth. The two main brands are being quoted as either 9 or 12. Where I live, dark skies are a given.

[sixela]

I've used Thousand Oaks, Astronomik, Lumicon and Baader H-betas.

What works best depends on the objects. By far the most aggressive one (save the professional filters like the Customs Scientific ones, which are very much like the Baader) is the Baader, and it works wonders but you'll be working with slightly larger exit pupils (yes, it says it's a "CCD" filter but it works very well visually).

For the Horsehead you might want a slightly less aggressive one if you have very dark skies and a 200mm scope, because seeing the horsehead shape clearly as a horsehead and not just a notch in IC434 already requires 80x-90x or more.

For things like the California nebula, the Baader's perfect, though, and it's better than anything else if your skies are anything but pristine or if you have a large scope.

Under pristine skies and with a scope smaller than 16" or so, the Lumicon is slightly better. Still a fairly narrow passband but slightly better transmission in H-beta (95% or so vs. 75-85% for the Baader depending on how well the passband is located around H-beta).

The Astronomik really does have very good transmission but the passband is a lot larger, so unless you have extra black skies I don't think it's as good as the Lumicon. And if you have extra dark skies, a very good narrow UHC-type filter (like a Lumicon or an Omega Optical NPB) passes H-beta anyway and using a H-beta might not be that necessary anyway (from the best sites the California nebula and the Horsehead are accessible with an NPB almost as easily as with a H-beta).

Doesn't happen that often for the Horsehead from our latitudes, though. If there's even a hint of light domes, Orion partly sits in them.

p.s. my favourite one is the Baader, but I have a large scope and only moderately dark skies.

[Guest]

OK having checked both Lumicon and Astronomik they both advertise 9nm (not Angstrom filters) (1nm = 10A). I have used both of these brands and they are both good. I have seen the Horsehead in both of them. Which is better? Astronomik probably use a better substrate although my Lumicon is very old now.

Owen

[Mark at Beaufort]

Are we talking of visual or astro imaging?

I have a Thousand Oaks 1.25" H-Beta line filter which I undestand has a narrow 12 Ångstrom passband with very steep cut-off slopes centered on the nebula emission line of hydrogen-beta at 4861Å.

To be honest I have tried to view the Horsehead, Cocoon, and California Nebulas in my 10" Dob from my home dark site without any success.

Perhaps I need to go bigger!!

Mark

[Doc]

This is what I wanted to do with my 16" dob but never got round to it.

So the 9A is imaging and a 90A is visual?

[ollypenrice]

I have only seen the Horse in our 20 inch and it just looks like a notch out of some incredibly faint nebulosity. That was with a UHC. I would be curious to see what you find if you buy an Hbeta.

Olly

[KenG]

Now this is interesting. Having read the excellent feed-back, I had another look at various adverts for H-Beta filters and found that some specify 9 Angstrom, and some 9nm. Also, 9 Angstrom and 12 Angstrom are being quoted on different webstes for the same Thousand Oaks filter. And none of the filters are recommended for astrophotgraphy. So back to the question, is there a performance difference between 9 and 12 Angstrom, and what's the difference between 9 Angstrom and 9nm?

[Guest]

As noted 1 nm = 10 Angstroms so it is the width of the filter i.e. how much light it lets through. 9A would be a very narrow filter and if the line width was sufficiently broad I would not think it would get through hence I think the adverts are confused and the bandwidth is 90A. If you have a 120A bandwidth I would have thought you might get some light in from the OIII line at 4959A (H-Beta is a t4861A) as the bandwidth is normally quoted at the FWHM. You will get better contrast with the narrower band.

To answer Ollies question you do get better contrast with the H-Beta filter compared to the UHC (at least in my 20")

Owen

[KenG]

Thanks Owen, that's good information.

Ken

[sixela]

OK having checked both Lumicon and Astronomik they both advertise 9nm (not Angstrom filters) (1nm = 10A).

What they advertise isn't really what matters. What they actually do is more important.

Hbeta-Filter

[sixela]

I have only seen the Horse in our 20 inch and it just looks like a notch out of some incredibly faint nebulosity.

That's what it also looks like in a H-beta unless you apply some more power. But as I said, at 90x and above I can clearly see the Horsehead shape in SQM 21.0 skies with a 16" and a H-beta filter, and you have a larger scope and better skies...

If you think that nebulosity (IC434) is faint, wait till you try even the brightest knots of Simeis 147 .

[acey]

I've seen the Horsehead with a 12" and UHC. You are of course looking for a missing notch in the surrounding faint nebula. There's not a lot to see: I'm personally not tempted to fork out for an H-beta to get a better view of it.

[Talitha]

I have only seen the Horse in our 20 inch and it just looks like a notch out of some incredibly faint nebulosity. That was with a UHC. I would be curious to see what you find if you buy an Hbeta.

Olly

I'll let you know, Olly.

Got a nice glimpse of it in December using a UHC with the 16" LightBridge when the transparency was average and the HH was within 30 degrees of the horizon. The view was encouraging enough to make me finally order the H-Beta i'd been tempted to purchase all these years. It's on order and should be here by February. When it gets here, hopefully it'll be clear out and the temperature will be above -20C.

[jabeoo1]

A recent article in July 2014 Astronomy magazine discussed a range of filters & their uses, including H-Beta.  It kind of concluded that the filter based on £/object offered not too great value for money.  However it stated that Barnard 33 was viewed with an instrument of 5 inch aperture !  (the conditions must have been immaculate i guess).

Don't forget the California Nebula & Cocoon nebula are also good candidates. 

Is it a 3 birds one stone filter then?
 

[scarp15]

A recent article in July 2014 Astronomy magazine discussed a range of filters & their uses, including H-Beta.  It kind of concluded that the filter based on £/object offered not too great value for money.  However it stated that Barnard 33 was viewed with an instrument of 5 inch aperture !  (the conditions must have been immaculate i guess).

Don't forget the California Nebula & Cocoon nebula are also good candidates. 

Is it a 3 birds one stone filter then?

No not necessarily just three objects (there is an article by David Knisely on Cloudy Nights in which he has compiled at least 19 targets a H-beta filter may benefit). In addition it will draw out features within the Orion Nebula such as with M43 and reveal additional detail in M42 that an OIII or UHC filter may not reveal (though not necessarily providing a better overall view). I am still getting accustomed to mine and have so far had little experience with it and expect that many of the targets will be challenging and subtle at best. I am looking forward to learning how to use it more extensively though. I have only included the addition of this expensive filter because I feel that I am lucky enough to gain access to dark sky locations in which to use my dobsonian.

Just to add that there has been some interesting discussions on here recently by Jetstream (Gerry) who has applied the H.B filter to varied targets, such as the North American Nebula amongst other targets in Cygnus with interesting outcomes. Search under the Observing sections. 

[John]

I have the Lumicon H-Beta filter. I've not had much success with it thus far but I'm hoping to push it's range a bit further during the Autumn and Winter. For the Horsehead Nebula I've acquired a 20mm Tele Vue plossl eyepiece which gives an optimal exit pupil for using this filter with my 12" dobsonian. I did try it on M42 this spring but I was not overwhelmed with the results to be honest.

[Tiki]

Has anyone ever tried an H-beta filter on the California Nebula?

[scarp15]

Yes that is how I considered it to be with M42 John preferring the actual view with either my OIII filter or for that matter unfiltered. However I intend to go back to this with a little more specific scrutiny. I have obtained the 25mm TV plossl for the same intention, which will provide an exit pupil of 4.72mm at 74x mag with the paracorr or used without 5.4mm 64x mag.

I had considered the 20mm to but I already use a 20mm nagler (which I will also attempt), though there are more glass elements in the light path and of course a wider field which will not as easily keep the brighter stars out of the field. Anyhow from what I can gather an exit pupil of between 3mm to 5mm and magnification around 70X to 110X is the optimum means to tackle this. Look forward to trying again anyway.  

[Mark at Beaufort]

I have had a Thousand Oaks H.Beta filter for many years and have not seen the California Neb with any of my scopes from a reasonably dark site. I have only seen the HH Neb once using a H.Beta filter and that was with a 16" Dob (not mine).

[jetstream]

Yes that is how I considered it to be with M42 John preferring the actual view with either my OIII filter or for that matter unfiltered. However I intend to go back to this with a little more specific scrutiny. I have obtained the 25mm TV plossl for the same intention, which will provide an exit pupil of 4.72mm at 74x mag with the paracorr or used without 5.4mm 64x mag.

I had considered the 20mm to but I already use a 20mm nagler (which I will also attempt), though there are more glass elements in the light path and of course a wider field which will not as easily keep the brighter stars out of the field. Anyhow from what I can gather an exit pupil of between 3mm to 5mm and magnification around 70X to 110X is the optimum means to tackle this. Look forward to trying again anyway.  

Iain, I didn't know you have the 25mm TV plossl, I just ordered one after some deliberation on which EP to get in addition to the 18mm BCO for the HH. I understand the 25 TV works well.

This purchase was finally made after what I saw with the cheap "Super 25mm" included with the VX10 - keeping  52 Cygni out of the FOV with this EP gave very,very fine, delicate filaments or strands seen in the Witches Broom ( at the split) with the OIII (Lumicon), an incredible sight for the 10". It also proved itself on the Cocoon with the Astronomik Hb. So the thought is the TV will squeak a bit more out of the Hb....and I'll need all the help I can get on the HH.

I have seen numerous nebula with the Hb, that huge dark region in Cygnus, IC 1318 is worth exploring from dark skies, as are the smaller nebs in Auriga, Flaming Star etc. + NA, California nebs and many more. I only wish I had bought a 2" Hb, for use with my widefields on the bigger nebula.

IC 1318 is for sure worth a look Iain.

[Merlin66]

Guys,

We're definitely taking about bandwidths in nm not A.

For what it's worth, the normal Hbeta emission is 50% that of the Ha emission...extra dusty environment may change the ratio slightly.

This infers that you would record twice as much light in the same object just with an Ha filter.....

[scarp15]

Iain, I didn't know you have the 25mm TV plossl, I just ordered one after some deliberation on which EP to get in addition to the 18mm BCO for the HH. I understand the 25 TV works well.

This purchase was finally made after what I saw with the cheap "Super 25mm" included with the VX10 - keeping  52 Cygni out of the FOV with this EP gave very,very fine, delicate filaments or strands seen in the Witches Broom ( at the split) with the OIII (Lumicon), an incredible sight for the 10". It also proved itself on the Cocoon with the Astronomik Hb. So the thought is the TV will squeak a bit more out of the Hb....and I'll need all the help I can get on the HH.

I have seen numerous nebula with the Hb, that huge dark region in Cygnus, IC 1318 is worth exploring from dark skies, as are the smaller nebs in Auriga, Flaming Star etc. + NA, California nebs and many more. I only wish I had bought a 2" Hb, for use with my widefields on the bigger nebula.

IC 1318 is for sure worth a look Iain.

Hi Gerry I had noticed that you had recently purchased this plossl. Your initial impressions of using a similar plossl e.p are interesting and it could become the eyepiece that best works with a H-beta filter on a number of faint diffuse nebula.  I will aim to try for IC 1318 and particularly look forward to the approaching seasonal challenges.   

[John]

Hi Gerry I had noticed that you had recently purchased this plossl. Your initial impressions of using a similar plossl e.p are interesting and it could become the eyepiece that best works with a H-beta filter on a number of faint diffuse nebula.  I will aim to try for IC 1318 and particularly look forward to the approaching seasonal challenges.   

I've recently bought a 20mm TV plossl for the same reason. With my 12" dob it gives a 3.8 mm exit pupil which I believe is in the right range for effective use of the H-Beta filter under my typical skies and the very high measured light transmission figures of the eyepieces was an attraction too. I did consider the 25mm but I felt that the additional magnification (= darker background sky) and smaller true field of the 20mm with my scope might help tip the balance a little further in my favour.

I have also washed my primary and secondary mirrors, part flocked the scope and blackened the secondary edge since I last tried for these faint objects so, short of buying a larger aperture scope, I'm as ready as I can be I think.

We will see !