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Stargzalex

Should I buy an H-Beta filter?

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(I'm posting in the eyepiece section, can't find the right one)

Hello everyone,

I have a question on H-beta filters, because I'd like to observe nebulae as the Horsehead Nebula.... but other amateur astronomers advised me against doing that. 

I own a f/6 200 mm (~8 inches) Dobson telescope and the set of eyepieces shown here:

They told me I could not use it at its best, because (if I remember right), my telescope is too small. 

And in case of buying one of these, 2" or 1.25"? There are diffuse nebulae that are wide... but the Horsehead is tiny instead (8' x 6'). 

I'm a bit confused...

Thanks you in advance for your advices and explanations :smiley:

 

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I have used an H-beta filter on the Horse-Head Nebula successfully with an 8" scope (Celestron C8). Working at a large exit pupil (around 3-4mm) I could  just make it out. UHC and O-III did not work. Your scope is big enough, but you will need very dark and transparent skies

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Perhaps if you haven't already you might like to refer to, 

http://www.perezmedia.net/beltofvenus/archives/000379.html

If this is to be your first filter, you would be better served with a UHC or OIII and become accustomed to filter observing easier, more dependable and impressive deep sky objects to begin with and your F6 8" scope is very much capable of that. However as Michael has indicated, for B33 a H-beta filter, dark transparent skies, Orion located at its highest point, full dark adaption, patience, correct exit pupil, which varies from person to person, 4mm-5mm exit pupil perhaps a little less, research and exceptions for what is a difficult subject to search for.  

 

 

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We already talked about this once:-) I'll just answer to the second part of your question: if you can, always buy 2 inches filter. You can screw a 2 inches filter to a 1.25 inches adapter, if it's threaded (yours should be, but it's not expensive to buy a threaded one,anyway ) to use it with smaller eyepieces, but never the opposite! 

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32 minutes ago, scarp15 said:

Perhaps if you haven't already you might like to refer to, 

http://www.perezmedia.net/beltofvenus/archives/000379.html

If this is to be your first filter, you would be better served with a UHC or OIII and become accustomed to filter observing easier, more dependable and impressive deep sky objects to begin with and your F6 8" scope is very much capable of that. However as Michael has indicated, for B33 a H-beta filter, dark transparent skies, Orion located at its highest point, full dark adaption, patience, correct exit pupil, which varies from person to person, 4mm-5mm exit pupil perhaps a little less, research and exceptions for what is a difficult subject to search for.  

 

 

Not my first.. I already have OIII filters I regularly use on nebulae... :)

Thanks for the link! I'll read it carefully... Wonderful reference!

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14 minutes ago, GuLinux said:

We already talked about this once:-) I'll just answer to the second part of your question: if you can, always buy 2 inches filter. You can screw a 2 inches filter to a 1.25 inches adapter, if it's threaded (yours should be, but it's not expensive to buy a threaded one,anyway ) to use it with smaller eyepieces, but never the opposite! 

Thanks Gu... You know - I'm stubborn:icon_biggrin: 

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27 minutes ago, GuLinux said:

We already talked about this once:-) I'll just answer to the second part of your question: if you can, always buy 2 inches filter. You can screw a 2 inches filter to a 1.25 inches adapter, if it's threaded (yours should be, but it's not expensive to buy a threaded one,anyway ) to use it with smaller eyepieces, but never the opposite! 

12 minutes ago, Stargzalex said:

Thanks Gu... You know - I'm stubborn:icon_biggrin: 

...and forgetful :blush:

 

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There are certainly additional dark and diffuse nebula targets that could be included extending that list yet further. They can (if revealed at all) be fairly underwhelming, but do make for interesting and absorbing challenges. The one real success I have had to date has been with NGC 1499, California nebula. This is relatively straight forward to observe (under a dark sky of course), at least cruising along the 'brighter' outer edge and is achievable with direct vision. By comparison, the filter is useful for accentuating M43 and can provide interesting if severe contrast with M42. I have also glimpsed B33 on one occasion two years ago. It will 'reveal' the reflection / diffuse nebula The Cocoon, but this object is hard to discern within its overlapping open cluster, the dark nebula B168, feeding into it is a little easier to determine. I am though looking forward to trying the filter on aspects of Barnards Loop and once again for the Horsehead, equally attempting diffuse nebula in Auriga - that has returned to the early morning sky. IC 2177 the Seagull nebula in Monoceros is also on my list for this filter. It is useful to trial and compare using a H-beta along with other filters such as a UHC on selective targets, a larger exit pupil is also a noticeable requirement. An example and another hard challenge would be the Cone nebula , also in Monoceros, achievable so I believe in excellent conditions with either a UHC or H-beta.

It is trial and error, I have attempted faint nebula in Cygnus without success, however if your passion is for venturing to a dark sky location and hunting for diffuse and emission nebula, in which some are attainable and others require perfect conditions, a H-beta filter is an integral requirement.  

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Your first filter should be a narrowband filter that transmits the H-Beta AND O-III lines in the spectrum.

Your second filter (almost as useful, but not quite) should be an O-III filter that transmits both O-III lines but not the H-Beta line in the spectrum.

Your third filter should be a good broadband filter for picking up nebula details with just a small amount of enhancement.

Your 4th, and last, filter should be the H-Beta filter for the exceedingly faint hydrogen gas emission nebulae, like IC434 behind the Horsehead (B33).

Judging from my over 30 years with nebula filters, you'll use them, percentage-wise, in just that order.

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I would like to quickly add the following: Don's post above is completely correct in using of these filters. And if you think of using coloured filters - the one and perhaps - only one you should get is the No.80A - Blue. The 80A does good things to bring out finer details in the most objects, including the Moon and planets. That's why it has been referred to as "The Swiss-Army Knife of filters."

All the best -

Dave

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On 2016-09-09 at 06:08, Stargzalex said:

(I'm posting in the eyepiece section, can't find the right one)

Hello everyone,

I have a question on H-beta filters, because I'd like to observe nebulae as the Horsehead Nebula.... but other amateur astronomers advised me against doing that. 

I own a f/6 200 mm (~8 inches) Dobson telescope and the set of eyepieces shown here:

They told me I could not use it at its best, because (if I remember right), my telescope is too small. 

And in case of buying one of these, 2" or 1.25"? There are diffuse nebulae that are wide... but the Horsehead is tiny instead (8' x 6'). 

I'm a bit confused...

Thanks you in advance for your advices and explanations :smiley:

 

Your scope is not too small to see the HH, I see it in my 10" 1200mm @ 48x and a 5.2mm exit pupil with the Hb. Your 30mm eyepiece will show it for you.... dark, transparent skies are needed as is the Hb, eventhough a tight UHC will show it. A great test is the Flame nebula, it should show easily and with a bit of structure with no filter- if you can see this then the faint thin thread of IC434 will be seen with the Hb, and the HH is just a "notch" out of this nebula.

Go for the Hb and choose wisely....

I too am a nebula hunter, good luck in your pursuit,Gerry

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While I don't doubt Michael's ability to see the HH in an 8 inch I certainly doubt my own. I've seen it three times in our 20 inch under skies SQM 21.5 to 21.9 but, even then, 'seen' needs to be qualified. I could see an oblong gap in the faint emission nebulosity. Two of these sightings were with a simple UHC and one with an H beta. I had hoped the H Beta would be a transforming experience but it wasn't.

Olly

Edited by ollypenrice
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4 hours ago, Stargzalex said:

Thanks everybody for your advices!

Your welcome, out of curiosity what is your NELM of your dark site(s)? This will be the telling tale... another thing that can be an influence are eyepieces... not sure if this is swaying off topic, if so sorry in advance.

Briefly, keeping Alnitak at "bay" is a big asset, if your 30mm scatters light to any degree it can wash out IC434. There are advantages to narrow FOV eyepieces for this object, my favorite is the 25mm TV plossl, they keep Alnitak out of sight with little scatter, enhancing perceived contrast of the object. A Vixen 30mm NPL or a Baader 32mm BCO might be worth a try if your 30mm doesn't show it.

I own a great Astronomik 1.25" Hb and a so so ( so far) 2" Lumicon Hb- if your only goal is the HH go for the 1.25", if objects like the California neb are desired go for the 2". Most Hb objects are underwhelming IMHO.

One last thing- I own narrow eyepieces for faint nebula to keep bright stars out of the FOV, regardless of their scatter levels- for practise try it on the Veils thin thread, keeping 52 Cygni out of the FOV.

We are eagerly waiting your reports!

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      I bought an O-III filter for my 200p a couple of years ago and it was certainly worth acquiring for stunning views of the Veil Nebula. It was a real "magic wand". I'm now thinking of a H-beta filter and I was wondering if it's going to be worth it. I see that some H-betas are recommended for CCD imaging use rather than visual. I see that the Astronomik H-beta filter is good for visual observation, with an 8" scope at the bottom of its suggested aperture range, but it is quite pricey. I would value any opinions positive or otherwise.
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